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March-2015

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of 56

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Clinical Publication - 1




Emmanuel C Mbalisike Tomas J.Vogi Stefan Zangos Katrin Elchier

Prakash Balakrishnan Jijo Paul

Basri Johan Jeet Abdullah Chai Hong Yeong Khean Lee Goh Boom Koon Yoong Gwo Fuang Ho

Carolyn Chue Wal Yim Anjali Kulkarni

Basri Johan Jeet Abdullah Chai Hong Yeong Khean Lee Goh Boom Koon Yoong Gwo Fuang Ho

Carolyn Chue Wal Yim Anjali Kulkarni

Michele Anzidei Renato Argiro Andrea Porfiri Fabrizio Boni Marco Anile Fulvio Zaccagna

Domenio Vitolo Luca Saba et al

Image-guided microwave thermoablation of hepatic tumours

using novel robotic guidence: an early experience

Robotic-assited thermal ablation of liver tumours

Robot-assited radiofrequency ablation of primary

and secondary liver tumours: early experience

Preliminary clinical experience with a dedicated

interventional robotic system for C-guided biopsies of lung

lesions: a comparison with the conventional manual technique

5

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Yilun Koethe Sheng Xu Gnanasekar Velusamy Brand J.Wood Aradhana M.Venkatesan

CM Chu* SCH Yu

From International Cancer Imaging Society(ICIS) 14th Annual eaching Course

Heidelberg. Germany 9-11 October 2014

Amarnath Chellathurai Saneej Kanhirat Kabilan Chokkappan Tiruchendur S Swaminanthan,

Nadhamuni Kulasekaran

Barnard Institue of Radiology, Madras Medical College, Government General Hospital,

Chennai-600033, India

Accurancy and efficacy of percutaneous biopsy and ablation

using robotic assistance under computed tomography guidance: a phantom study

Robot-assited navigation system for C-guided

percutaneous lung tumor procedures: our initial

experience in Hong Kong

echnical note : C-guided biopsy of

lung masses using an automated guiding

apparatus



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50 Clinical Publication - 8



F. Cornells H. akaki M. Lakshmanan J.C. Durack J.P. Erinjeri G.I.Getrajdman M. Maybody

C.. Sofocleous S.B. Solomon G. Srimathveeravalli.

Boris Sehulz, M.D. Katrin Eichler, M.D. Firas Al-Butmeh, M.D. Claudia Frellesen, M.D. Tomas Vogl, M.D. Christoph Czerny, M.D. Stephan Zangos, M.D.

Robot assisted percutaneous placement of K-wires during minimal invasive

spinal interventions

Christoph Czemy 1 Katrin Eicher2 Boris Schulz2 Chirstof Schomerus3 Tomas J.Vogl2

Ingo Marzi and Stephan Zangos

Computed omography guided percutaneous

liver biospy using a robotic assistance device

corpse study.

Department of Diagnostic and Interventional Radiology, University Hospital Frankfurt,

Goethe-University,Frankfurt am Main,Germany

Comparison of C Fluoroscopy-Guided Manual and C-Guided

Robotic Positioning System for In Vivo Needle Placementsin Swine Liver

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INTERVENTIONAL

Image-guided microwave thermoablation of hepatic tumoursusing novel robotic guidance: an early experience

Emmanuel C. Mbalisike & Thomas J. Vogl &

Stefan Zangos & Katrin Eichler & Prakash Balakrishnan &

Jijo Paul

Received: 31 March 2014 /Revised: 8 July 2014 /Accepted: 13 August 2014# European Society of Radiology 2014

AbstractObjective To evaluate and compare novel robotic guidance

and manual approaches based on procedural accuracy, proce-

dural time, procedural performance, image quality as well as

patient dose during image-guided microwave thermoablation.

Method The study was prospectively performed between

June 2013 and December 2013 using 70 patients. Forty ran-

domly selected patients (group 1) were treated with manual

guidance and 30 patients (group 2) were treated using a novel

robotic guidance. Parameters evaluated were procedural ac-

curacy, total procedural time, procedural performance,

quantitative/qualitative image quality and patient dose. Two-

sided Student ’s t test and Wilcoxon rank-sum test were used totest the significance of the data and p values less than 0.05

were considered statistically significant.

Result Accuracy parameters were significantly higher ingroup 2 (all p <0.05). Total procedural time showed a mean

time difference of 3 min (group 2>group 1; p=0.0008).

Volume CT dose index and dose – length product were signif-

icantly lower for group 2 compared to group 1 (all p<0.05) for

CT fluoroscopy imaging. Total procedural performance score

was higher for group 2 compared to group 1 ( p=0.0001).

Image quality parameters were insignificant between exam-

ined groups.

Conclusion The novel robotic guided approach improved the

accuracy of targeting the target tumour, reduced patient dose

and increased procedural performance (which influences the

procedural safety) during ablation. Key Points

• Few reports are available in the literature regarding robotic-

assisted liver microwave ablation.

• The robotic guided approach improved accuracy of localiz-

ing the target tumour .

• Radiation dose on patients was reduced with the robotic

guidance.

• Numbers of insertions and readjustments were reduced ,

lowering chances of complications.

Keywords Microwave thermoablation . Robotic guided

approach . Procedural accuracy . Hepatic tumours . Patient

dose

Introduction

Microwave thermoablation therapy is heating to denature the

protein content of ablated solid tumour and surrounding soft

tissue. The therapy can either be curative or palliative for

patients with inoperable tumours and/or for dangerous surgi-

cal procedures; furthermore, it could also be a neoadjuvant

option to systemic chemotherapy in cases of hepatic/

E. C. Mbalisike (*)

Institute for Diagnostic and Interventional Radiology, K linikum Bad

Salzungen, Lindigalle 3, 36433 Bad Salzungen, Germany

e-mail: [email protected]

T. J. Vogl : S. Zangos : K. Eichler : J. Paul

Institute for Diagnostic and Interventional Radiology, Johann

Wolfgang Goethe University Hospital, Theodor-Stern-Kai 7,

60590 Frankfurt, Germany

T. J. Vogl


S. Zangos


K. Eichler


J. Paul


P. Balakrishnan

Perfint Healthcare Pvt. Ltd. (HO), No. 16, Southwest Boag Road,

T. Nagar, Chennai 600017, TN, India


Eur Radiol

DOI 10.1007/s00330-014-3398-0


This is for information and educational purpose only




extrahepatic infiltration [1, 2]. It is a minimally invasive

treatment option which could also be relatively cumbersome

for both patients and interventional radiologist. Therapy re-

quires insertion of a microwave applicator into the hepatic

tumour; moreover, several trials of insertion may be required

to accurately localize the target tumour. This is usually thecase with tumours less than or equal to 3 cm in diameter [3, 4].

Multiple trials of insertion, depth, location and size of the

hepatic tumour would affect procedural safety for the patient

as well as treatment outcome at the end of the procedure,

which could lead to several complications, such as bleeding

around the puncture region [5, 6].

The increase in patient dose is dependent on the number of

CT examinations performed to localize the target tumour [7];

furthermore, in manual CT-guided microwave ablation thera-

py procedure, a relatively high radiation exposure to both

patient and procedural personnel is expected [7, 8]. Increasing

needle depth, insertion and number of needle repositionings

into a target tumour during an ablation procedure increases the

probability of developing complications that could be

life-threatening [5]. The introduction of the robotic

guidance system in surgical/interventional settings for

procedural planning, holding and moving instruments

precisely to allow better precision as well as accuracy

has been reported [9, 10]. The use of a robotic system

for image-guided real-time planning and intraprocedural

guidance during microwave thermoablation is still in its

pilot stages. This study was formulated with the aim to

assess and compare a novel robotic guidance with a

traditional manual approach during hepatic microwave

thermal ablation therapy procedure. In addition we eval-

uated procedural accuracy, procedural time, procedural

performan ce, ima ge qua lit y and patien t dose during

microwave therapy.

Materials and method

This study was prospectively performed between June 2013

and December 2013. Institutional review board approval and

informed consent were obtained.

Patient demography and assessment

A total of 70 patients underwent CT-guided microwave

thermoablation therapy of various hepatic tumours in 70 ses-

sions (one tumour/session) and the treated liver tumours were

of heterogeneous origin (primary and secondary; Table 1). Out

of 70 randomly selected patients, 40 patients (60±10 (46 – 82);

male, 25; female, 15) were treated by the manual approach

(group 1) and 30 (57.7±15 (33 – 83); male, 19, female, 11)

were treated using novel robotic system (MAXIO, Perfint

Healthcare, India; group 2) guidance.

O n l y p a t i e n t s w h o r e c e i v e d t r a n s a rt e r i a l

chemoembolization therapy (TACE) within 3 months prior

to thermoablation sessions were included in this study. During

CT-guided thermoablation, the presence of Lipiodol (deposit-

ed during TACE) helped to properly visualize and delineate

the target tumour [11]. Further patients included on the basis

of the aforementioned criteria were those with surgically

unresectable liver tumours, poor candidates for surgery due

to accompanying previous medical history, patients who

underwent previous multiple surgeries for recurrent metasta-

ses, those with at most five tumours and no greater than about

5 cm in maximal axial tumour diameter. Patients excluded

were as follows: those with uncontrolled primary malignancy,

wide diffused metastatic spread, more than five tumours/pa-

tient, tumours larger than 5 cm in maximal axial tumour

diameter, radiological evidence of lymph node metastases,

uncorrectable coagulopathy (international normalized ratio

Table 1 Tumour characteristics

and number of patients recruited

for this study and the corre-

sponding mean maximal tumour

diameterfor each tumour subclass

treated using either the manual or

robotic guided approach

Tumour characteristics Patient number Total number of

tumours

Maximal tumour diameter

(MTD in mm)

Manual MAXIO Manual MAXIO Manual MAXIO

Primary tumours

Hepatocellular carcinoma 13 11 31 33 22×19 23×21

Cholangiocarcinoma 9 10 23 29 24×21 23×22

Metastasis from

Renal cell carcinoma 3 0 8 0 34×26 0

Thyroid carcinoma 1 1 3 2 24×23 21×18

Breast carcinoma 3 2 10 5 36×31 22×19

Gastric carcinoma 1 0 2 0 35×32 0

Colon carcinoma 4 3 13 9 21×18 32×31

Sigmoid carcinoma 0 1 0 2 0 29×24

Rectal carcinoma 2 1 6 3 20×18 32×28

Pulmonary carcinoma 4 1 14 2 23×22 25×21

Eur Radiol




1.8 or platelet count 75,000), septicaemic patients and/or the

patients who refused thermal ablation. The treatment plan was

determined for all patients by the interventional radiologist in

conjunction with a multidisciplinary tumour board consisting

of health care staff members from surgical and medical on-

cology. No patient treated by either the group 1 or 2 approachrequired a long stay in hospital (more than 24 h).

Tumour localization

An initial unenhanced CT (Somatom Sensation 64; Siemens

Healthcare, Erlangen, Germany) imaging was performed for

all patients to identify the target region, tumour size and

anatomical location. This was followed by either a manual

or robotic guided procedure to localize the target tumour

(Fig. 1). Manual tumour localization was performed using

CT fluoroscopy for group 1 patients by placing two radi-

opaque copper metal wires over the region of interest

(Fig. 2). CT fluoroscopy is a sequence of CT imaging that

generates a single slice per CT exposure. Then a mark was

drawn on the patient ’s body using a marker pen to represent

the point of insertion of the microwave applicator. During the

group 2 procedure, patients were placed on an inflatable

mattress (SecureVac; Bionix radiation therapy, Toledo, Ohio)

secured to the CT table. This mattress was required to hold

and keep the patient in position to avoid or minimize move-

ment that would affect the positioning of the robotic guiding

system. Patient movement during CT examination or micro-

wave therapy was not significant enough to affect the therapy

procedure. The robotic system start-up was initialized before

docking was performed; this was followed by loading the

initially acquired unenhanced CT data into the system soft-

ware. Loaded data were then registered and reconstructed into

axial, coronal and sagittal planes which were then used for

plann ing. Tumour del ineat ion and seg mentati on were

performed in a 3D format to arrive at a virtual representation

of the proposed ablation volume (Figs. 3, 4a). This helps to

rule out possible areas of the patient ’s anatomy that could be

considered as “no go”, since injury to these structures could

lead to treatment complication (Fig. 4a ). Planning is achieved

by setting the entry point on the skin’s surface and the target point inside the tumour. During planning, “no go” regions

were regarded as regions close to a major anatomical

structure/organ or close to the liver capsule for peripheral

lesions. These aforementioned regions could then be excluded

from the virtual ablation volume using the software built for

that purpose. While planning, system software provides the

required needle length, needle entry point and possible abla-

tion volume (based on manufacturer information for user,

IFU) for each selected applicator (Fig. 4b). These system-

planned parameters were then confirmed by the radiologist;

on the basis of this confirmation, the robotic arm automatical-

ly moves to the prescribed position over the patient ’s anatomy.

Thermoablation procedure

All microwave thermoablation therapies were performed in

aseptic conditions by two interventional radiologists with

more than 5 and 15 years of experience in abdominal inter-

vention, respectively. A mixture of sedative and analgesic

medication with fentanyl citrate (1 mg per kilogram of body

weight) and midazolam hydrochloride (0.010 – 0.035 mg/kg)

was titrated by the interventional radiologist until the patient

could tolerate the ablation procedure. Microwave applicators

used were either one of the following: Covidien (Covidien

Deutschland GmbH; applicator length, 12, 17 or 22 cm; emit-

ting portion, 3.7 cm), Amica (Hospital Services SpA, Aprilia,

Italy) applicator length, 15 or 20 cm; emitting portion, 2 cm

and Microsulis (Angiodynamics Inc, Amsterdam, the Nether-

lands; applicator length, 14 or 19 cm; emitting portion,

1.4 cm). Ablation time was controlled using the appropriate

software timer for all procedures. During the ablation proce-

dure, the applicator was advanced into the target tumour in a

pre-planned manner to achieve optimal overlapping ablation

zones. Then treatment was performed using appropriate mi-

crowave energy based on the radiologist ’s decision. At the end

of every session, applicator track coagulation was performed

to induce haemostasis and prevent malignant cells seeding in

the applicator track. The number of insertions (NOI) per-

formed with the applicator after each thermoablation proce-

dure for each patient was also noted. The same day after

thermoablation (within 24 h), a post-ablation unenhanced/

contrast-enhanced T1- and T2-weighted magnetic resonance

(MR) imaging was performed using a 1.5-Tesla Magnetom

Symphony (Siemens, Erlangen, Germany). Magnevist

(Schering, Berlin, Germany; 0.1 mmol/kg body weight of

gadopentetate dimeglumine) contrast material was used for

imaging for all patients (Fig. 2c).Fig. 1 Workflow chart for both manual and robotic guided approaches

Eur Radiol




Image and data analysis

Two independent radiologists with more than 12 years of

experience in abdominal imaging quantitatively and qualita-

tively evaluated the post-microwave ablation image data sets.

The image data sets were viewed on GEPACS (General Elec-

tric Picture Archiving Communication System, GE

Healthcare, Dornstadt, Germany). Quantitative image quality

parameters such as Hounsfield unit (HU), image noise, signal-

to-noise ratio (SNR) [12 – 14] and tumour conspicuity (TC)

were assessed. Attenuation values were measured at the liver

parenchyma and at the tumour by the aid of a circular tool

(ROI). The ROI was measured on the axial slices and standard

deviation from the mean CT density within the ROI was taken

Fig. 2 Axial CT images during manual guided approach used for patients

in this study. Notice the two white points (long white arrow) signifying

the radio-opaque copper wires which were placed on the patient ’s surface

in a and used to localize the target tumour. The target tumour was easily

visible in theunenhanced CTimages owing to thepresence of Lipiodolas

is represented in thefigure. b Location of the inserted microwave ablation

applicator (the applicator active point was located outside the tumour

centre and was readjusted to increase the accuracy of insertion). c Post

ablation (within 24 h) MR T1-weighted contrast enhanced images of the

same patient. Notice the ablation region (long white arrow) which could

be easily differentiated from the l iver parenchyma

Fig. 3 Unenhanced CT images

used for planning during robotic

guided approach. a Shows the

delineated tumour (long arrow)

and the tumour ( short arrow) in

liver segment 6. b Shows the

proposed point of entry from the

skin surface to the target tumour

signified by the purple line

Eur Radiol




as image noise. Maximal tumour diameter (MTD) was mea-

sured using a standard scale. SNR was determined using the

HU and image noise according to the following formula:

SNR=HU/image noise. Difference between the obtained HU

for the lesion and the liver was taken as TC [15]. Tumour

visibility was assessed qualitatively using a grading scale

(Table 2). Furthermore, procedural performance was deter-

mined for both groups on the basis of a five-point grading

scale (Table 2) and any arising complications were recorded.

These complications were classified into minor and major

categories [16]. Minor complications such as pain, soft tissue

burn, subcutaneous bleeding and antenna breakage were en-

countered during the manual method. Major complications

like intrahepatic and subcapsular haematomas were treated by

immediate termination of therapy, followed by selective em-

bolization (intrahepatic) or surgical drainage (subcapsular

haematoma). However, arising minor complications were

treated conservatively. Ablated region conspicuity (ARC)

was determined using the following formula: ARC=HU liver

−HUablated region; furthermore, ablated region dimension

(ARD) in centimetres was also determined using a standard

scale on contrast-enhanced MR images.

Further data collected by both radiologists were (1) proce-

dural accuracy parameters [such as skin-to-tumour depth,

applicator depth, applicator active point deviation from tu-

mour centre (AAD), applicator active point final position after

Fig. 4 a Shows the beginning of

liver segmentation, which helps

demarcate certain soft tissue

areas. b Shows the location of the

robotic arm after liver

segmentation signifying that the

robotic arm is ready for insertion

Table 2 Grading score obtained from two examiners for tumour visibility and overall procedural performance

Grading scale Tumour visibility Procedural performance

1 Undifferentiated hepatic tumour from parenchyma Severe complication with severe procedural difficulty

2 Mild differentiated hepatic tumour from parenchyma Minimal complication (early or late) and moderate procedural difficulty

3 Moderately differentiation hepatic tumour from parenchyma No complication, marginal procedural difficulty

4 Good differentiation hepatic tumour from parenchyma No complications, minimal procedural difficulty

5 Excellent differentiation hepatic tumour from parenchyma No complications or procedural difficulty

Eur Radiol




readjustment (AAFP) and number of readjustments] and (2)

total procedure time [including planning time, preparation

time (insertion time and ablation time)]. An explanation of

the assessed parameters is given in Table 3.

We collected radiation dose parameters such as CTDIvol

and dose – length product (DLP) from the system-generated patient protocol [17, 18]. An appropriate k factor (0.015 mSv/

(mGy cm)) for the abdomen was used to convert DLP to

effective dose (ED; mSv). We also noted the tube potential

(kV) and the tube current – time product (mAs).

Statistical analysis

BiAS 9.02 (Epsilon Verlag, Darmstadt, Germany) statistical

software was used to perform the statistical analyses for this

study and a p value of 0.05 was considered to be statistically

significant. Continuous variables such as patient age, MTD,

skin-to-tumour depth, applicator depth, AAD, AAFP, number

of readjustments, planning time, preparation time, insertion

time, ablation time, HU, image noise, SNR, TC, ARC, DLP

and CTDIvol were are reported as mean±standard deviation

and range. Quantitative parameters (HU, image noise, SNR,

TC, ARC, DLP, CTDIvol) were tested between the two

groups using the two-sided Student ’s t test. Wilcoxon’s rank-

sum test was used to examine the accuracy of the procedure,

total procedural time, procedure performance and qualitative

tumour visibility between the two groups.

Results

Procedural accuracy

Mean number of needle insertions per procedure was signif-

icantly ( p=0.0001) lower (48.7 %) in group 2 (2.1±0.73) in

comparison with group 1 (4.1±1.8; Fig. 2b). Mean AAD and

AAFP were significantly ( p=0.0002; p=0.0001) lower in

group 2 (5.3±1.8; 1.9±1.7) in comparison with group 1

(11.1±2.2; 6.2±1.7). Mean number of readjustments was

significantly lower ( p=0.0001) for group 2 (1.13±0.7) com-

pared to group 1 (3± 1.8; Table 4). The measured skin-to-

tumour depth and applicator depth were not statistically sig-

nificant between groups ( p=0.7498, p=0.3135).

Tumour size, visibility and conspicuity

With regards to MTD of the hepatic tumours, no statistically

significant difference was obtained between the two groups

( P >0.05; Table 4). The obtained SNR values measured for

both the liver and tumour were not significantly different

between the two groups ( p=0.7858, p=0.2901; Table 5).

The calculated TC values showed insignificant results ( p=

0.1626; Table 5) during comparison between groups. Quali-

tative values of tumour visibility obtained between groups

showed no statistical significance ( p=0.1785). Obtained

ARC showed no statistical significance between groups; fur-

thermore, ARD was also determined (Table 5).

Procedural duration

Mean insertion time was significantly lower ( p=0.0001) for

group 2 (1.5±0.57) compared to group 1 (2.9±1.3); whereas,

mean planning time and preparation time were lower for

group 1 (6.8±2.8, 3.8±0.75) than in group 2 (9.7±1.3, 5.4±

0.8; Table 4). Mean ablation time was not significantly differ-

ent between groups 1 and 2 ( p=0.7751). Mean total proce-

dural time was slightly higher ( p=0.0008) for group 2 (25.2±

2.8 min) compared to group 1 (22.15±3.95 min).

Radiation dose parameters

For the CT fluoroscopy image data acquisition, CTDIvol and

DLP were significantly lower for group 2 compared to group 1

( p=0.006; p=0.003; Table 6). CTDIvol and DLP between both

groups showed non-significant difference for the initial

unenhanced imaging ( p=0.4935; p=0.0521). The acquired

number of slices during unenhanced imaging was constant for

both groups; furthermore, CT fluoroscopy showed statistically

lower dose values ( p=0.0001) for group 2 compared to group 1.

Table 3 Definitions of the assessed parameters

Skin-to-tumour depth Distance from the skin surface to the centre of the tumour

Applicator depth Initial length of the applicator measured from the target tumour to the body surface

Applicator active point deviation (AAD) Distance of the applicator active point to the centre of the target tumour

Applicator active point final position (AAFP) Distance of the applicator active point to the centre of the target tumour after final readjustment

Number of readjustments Number of times the applicator was readjusted to better target the tumour centre

Planning time Time duration to plan either the group 1 or 2 approaches

Preparation t ime Time duration from the end of planning to the beginning of applicator insertion

Insertion time Time duration for an accurate insertion of the applicator into the target tumour

Ablation time Duration of the microwave thermoablation therapy

Eur Radiol




The calculated ED to the patient for the complete procedure

was lower (6.7 %) in group 2 compared to group 1 (Table 6).

Procedural performance

Procedural performance was better in group 2 (4.3±0.58) than

in group 1 (3.27±0.93) and showed statistically significant

difference ( p=0.0001). There were four complications report-

ed during thermoablation for group 1 (Tables 2, 4, 7); howev-

er, complications were completely absent with the group 2

treatment approach.

Discussion

The present study highlights the performance of a novel

robotic guidance during microwave thermoablation in

comparison to the manual approach. The robotic guided ap-

proach helps to reduce the number of applicator insertions

(which reduces the probability of complications arising),

shorten the insertion times, decrease the number of applicator

readjustments (improve the accuracy of the puncture) and

increase performance during the microwave thermoablation

procedure.

There were two minor and two major complications report-

ed in group 1; however, no complications developed in

group 2. It was reported that increased needle depth and

insertion into the target organ during an ablation procedure

could increase the chances of developing complications rang-

ing from mild to life-threatening haemorrhages [5]. The four

reported complications could have developed as a result of

multiple trials of applicator insertions into the ablation site;

moreover, the robotic approach provided no complications

owing to significantly reduced applicator NOI and

readjustments.

Table 4 Applicator accuracy pa-

rameters, procedural time and

performance grading score used

to assess the patients involved in

this study

Table also shows the number of

complications encountered during

the microwave procedure

Parameter Manual approach (group 1) MAXIO (group 2) P value

Maximal tumour diameter (mm) 22.3 ±11 (9 – 45) 23.2±8.4 (11 – 46) 0.0643

No of insertions/procedure 4.1± 1.8 (2 – 7) 2.1±0.73 (1 – 3) 0.0001

Skin to tumour depth (mm) 94.2 ±23.7 (60 – 151) 101.4 ±34 (61 – 166) 0.7498

Applicator depth (mm) 116±23.3 (80 –

140) 115 ±33.7 (80 –

135) 0.3135

Applicator active point deviation (mm) 11.1±2.2 (7 – 15) 5.3±1.8 (2 – 8) 0.0002

Applicator active point final position (mm) 6.2±1.7 (3 – 9) 1.9±1.7 (0 – 3) 0.0001

No of readjustment 3± 1.8 (1 – 7) 1.13±0.7 (0 – 3) 0.0001

Planning time (min) 6.8±2.8 (2 – 14) 9.7±1.3 (5 – 16) 0.0001

Preparation time (min) 3.8±0.75 (3 – 5) 5.4±0.8 (4 – 7) 0.0001

Insertion time (min) 2.9±1.3 (2 – 6) 1.5±0.57 (1 – 2) 0.0001

Ablation time (min) 8.6±2.56 (5 – 12) 8.5±2.48 (5 – 12) 0.7751

Total procedure time (min) 22.15 ± 3.95 (14 – 30) 25.2±2.8 (15 – 30) 0.0008

Performance score 3.27±0.93 (1 – 4) 4.3±0.58 (3 – 5) 0.0001

Complication 4 0

Table 5 Quantitative and quali-

tative image quality parameters

used to assess the images of pa-

tients treated with the microwave

procedure

Table also demonstrates the at-

tenuation difference (tumour con-

spicuity) between the lesion and

the liver for both groups evaluat-

ed; furthermore, it demonstrates

the mean dimensions (length×

breadth) of the ablated region

Image quality parameter Manual approach (group 1) MAXIO (group 2) P value

HU liver 54±8.6 (33 – 66) 58±9 (48 – 73) 0.0511

Noise liver 11.3±3.3 (7 – 17) 11.4±2.8 (7 – 17) 0.0692

HU tumour 35.3±7.6 (22 – 52) 40.9±15 (27 – 55) 0.0566

Noise tumour 13.9± 7.7 (7 – 19) 14.2±8.2 (8 – 21) 0.8435

SNR liver 5.35±1.9 (3 – 8) 5.5±1.7 (3.2 – 7.8) 0.7858

SNR tumour 2.9±1.5 (1.6 – 3.9) 3.5±1.4 (2.4 – 4.9) 0.2901

Tumour conspicuity (TC) −18.7±9 (−7.9 to −28.9) −17.1±10 (−6.5 to −26.9) 0.1626

HU ablated region 18.4±4.7 (10 – 30) 17.9±4.3 (14 – 27) 0.1188

Noise ablated region 18.8± 4.7 (12 – 24) 17.7±4.6 (10 – 25) 0.1122

SNR ablated region 1.1±0.5 (0.6 – 1.7) 1±4.6 (0.6 – 1.8) 0.1331

Ablation region conspicuity (ARC) 35.5±9.2 (21 – 46) 39.4±8.8 (26 – 46) 0.1022

Qualitative tumour visibility assessment 2.6±1.2 (2 – 4) 3±1.4 (2 – 4) 0.1785

A blated region dimensions (mm ×mm) 47.3×30.4 45.7×34.1 –

Eur Radiol




Certain number of readjustments was necessary to increase

the accuracy of the applicator placement at the centre of the

target tumour before microwave ablation. In the present study

we arrived at applicator deviations of 11.1 mm and 5.3 mm

respectively for group 1 and 2 approaches using patients

during our initial attempt. However, the applicator was

readjusted a few times to increase accuracy, which reduced

the applicator deviation to 6.2 mm and 1.9 mm respectively.

Previous studies on stable materials (phantoms and vertebra)

using robotic devices during fluoroscopic punctures arrived at

average needle tip deviations of 1.1 mm and 4.6 mm after

additional fine needle adjustments [19, 20]. It is of importance

to note that the two mentioned studies were performed on

stable structures in contrast to the present study, where the

patient ’s liver may have moved involuntarily. Furthermore,

obtained values were very close to those of the two previously

published studies.

Applicator insertion time (also NOI) was remarkably re-

duced for the robotic guidance approach compared to the

manual approach, as the robotic system was already posi-

tioned over the target region and clearly shows the puncture

location during applicator insertion. However, slight increases

in planning time and preparation time were seen in group 2

because of the additional time it takes for data registration,

software planning and movement of the robotic arm to the

target location. As a result of an increase in both planning and

preparation time, a slight but negligible increase in mean total

procedural time (3 min) was noticed during the robotic ap-

proach in comparison with group 1.

As regards to the procedure performance (Table 2), we

noticed that group 2 achieved higher scores than group 1. This

is due to reduced associated procedure complications and

procedural difficulty (owing to reduced insertion time and

improved accuracy of localizing the target tumour). Tumour

margins were delineated using real-time CT images, while

ablation regions were determined using ARC and ARD

values. As regards to tumour conspicuity, the attenuation

between the tumour and hepatic parenchyma showed good

difference in both groups, which aided the easy visual identi-

fication of the tumour. We further qualitatively analysed tu-

mour visibility, also allowing easy identification of the tu-

mours, aided procedural planning in both cases and confirma-

tion of the applicator in the tumour by the examiner.

Dose parameters such as CTDIvol and DLP were signifi-

cantly lower in the robotic guidance approach compared to the

manual approach during CT fluoroscopy imaging, which was

due to a reduced number of acquired slices. Calculated ED in

patients was decreased in the robotic guidance procedure com-

pared to the manual approach. This reduction was due to the

following reasons: reduced applicator NOI, reduced insertion

time and a reduced number of CT fluoroscopy imagings. This

confirms that using the robotic assisted CT-guided approach (as

in group 2) provides lower patient dose compared to the manual

approach (group 1) during the microwave ablation procedure.

A possible limitation associated with this study could be

the use of real-time CT imaging. Real-time ultrasound (US)

imaging has been used for image guidance purposes during

applicator placement since it eliminates patient dose, whereas

the robotic guided approach requires an initial CT or CT

images to be loaded from previous acquisitions. A further

limitation is the fact that this is an early experience; more

studies using more patients or multi-institutional studies to

explore the usefulness of the robotic system during

Table 6 Radiation dose parame-

ters and thetotaleffective dose for

both groups evaluated

Radiation dose parameters Manual approach (group 1) MAXIO (group 2) P value

Tube potential (kV) 120 120 –

Tube current time product (mAs) 130.9±43.9 (105 – 155) 132.5 ±30.5 (112 – 158) 0.8918

No of slices 42 42 –

CTDI vol (mGy) 7.6±3 (5 – 12) 8.1±1.6 (6 – 13) 0.4935

DLP (mGy cm) 190.9±93 (144 – 244) 193.8±93 (148 – 251) 0.0521

CT fluoro. Tube potential (kV) 120 120 –

Tube current – time product (mAs) 70 70 –

CT fluoro. no. of slices 34 ±10 (17 – 47) 22.2±7 (12 – 31) 0.0001

CTDIvol (mGy) 136.9±47 (94 – 175) 94.9±48.9 (51 – 121) 0.006

DLP (mGy cm) 70.2±23.6 (39 – 98) 49.2±19.5 (34 – 75) 0.003

Effective dose (mSv) 3.9 3.64 –

Table 7 Procedural performance level in relation to treated patients

based on grading scale explained in Table 2 during thermoablation

procedure

Grading scale Manual approach (group 1) MAXIO (group 2)

Grade 1 2 (5 %) 0 (0 %)

Grade 2 2 (5 %) 0 (0 %)

Grade 3 10 (25 %) 0 (0 %)

Grade 4 16 (40 %) 14 (46.6 %)

Grade 5 10 (25 %) 16 (53.3 %)

Mean and SD 8±6 6±7.4

Eur Radiol




interventional procedures may be useful. Another limitation

was the time duration required for robotic guidance system

set-up, planning and localization. If this time duration could

be reduced, this would go a long way to improve procedure

duration. From our point of view, the problem of time duration

could be solved if the vendor reduces the number of stepsrequired for planning and localization.

In conclusion, we would like to state that the robotic guided

approach can shorten the number of applicator insertions, short-

en the insertion time, decrease the number of applicator

readjustments (which reduces the chances of complications

arising), increase the accuracy of puncturing and improve pro-

cedural performance (which increased procedure safety) during

treatment of hepatic tumours. A significant reduction of

CTDIvol and DLP during CT fluoroscopy data acquisition

was achieved, reducing patient dose. We would like to further

state that the guidance of microwave ablation punctures using

robotic guidance needs to be thoroughly investigated using more

patient groups so as to unlock the maximum potential of this

technique and achieve precise localization of the target tumour.

Acknowledgments We would like to thank Mrs. Neddermann and Mr.

Ackermann of Johann Wolfgang Goethe University Frankfurt, Germany

as well as Dr. Anjali of Perfint Healthcare for their relentless support and

efforts during the time of this study. The authors would also like to

acknowledge and thank Perfint Healthcare India for allowing the use of

their MAXIO robotic system during the duration of the study. The

scientific guarantor of this publication is Jijo Paul, Ph.D. The authors of

this manuscript declare relationships with the following companies:

Prakash Balakrishnan, M.Sc. is an employer of Perfint Healthcare Pvt.

Ltd. The authors would like to thank Perfint Healthcare for loaning us

their system for our study. The authors state that this work did not receive

any funding. No complex statistical methods were necessary for this

paper. Institutional review board approval was obtained. Written in-

formed consent was waived by the institutional review board. The study

has not been reported before anywhere. Methodology: prospective, per-

formed at one institution.

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Eur Radiol




INTERVENTIONAL

Robotic-assisted thermal ablation of liver tumours

Basri Johan Jeet Abdullah & Chai Hong Yeong &

Khean Lee Goh & Boon Koon Yoong & Gwo Fuang Ho &

Carolyn Chue Wai Yim & Anjali Kulkarni

Received: 9 April 2014 /Revised: 20 June 2014 /Accepted: 7 August 2014# European Society of Radiology 2014

Abstract

Objective This study aimed to assess the technical success,radiation dose, safety and performance level of liver thermal

ablation using a computed tomography (CT)-guided robotic

positioning system.

Methods Radiofrequency and microwave ablation of liver

tumours were performed on 20 patients (40 lesions) with the

assistance of a CT-guided robotic positioning system. The

accuracy of probe placement, number of readjustments and

total radiation dose to each patient were recorded. The perfor-

mance level was evaluated on a five-point scale (5 – 1: excel-

lent – poor). The radiation doses were compared against 30

patients with 48 lesions (control) treated without robotic

assistance.

Results Thermal ablation was successfully completed in 20

patients with 40 lesions and confirmed on multiphasiccontrast-enhanced CT. No procedure related complications

were noted in this study. The average number of needle

readjustment was 0.8±0.8. The total CT dose (DLP) for the

entire robotic assisted thermal ablation was 1382±

536 mGy.cm, while the CT fluoroscopic dose (DLP)

per lesion was 352 ± 228 mGy.cm. There was no statis-

tically significant ( p >0.05) dose reduction found be-

tween the robotic-assisted versus the conventional

method.

Conclusion This study revealed that robotic-assisted planning

and needle placement appears to be safe, with high accuracy

and a comparable radiation dose to patients. Key Points

• Clinical experience on liver thermal ablation using CT-

guided robotic system is reported.

• The technical success, radiation dose, safety and perfor-

mance level were assessed.

• Thermal ablations were successfully performed, with an

average performance score of 4.4/5.0.

• Robotic-assisted ablation can potentially increase capabili-

ties of less skilled interventional radiologists.

• Cost-effectiveness needs to be proven in further studies.

Keywords Robot . Radiofrequency ablation . Microwave

ablation . Liver tumour . CT-guided

Introduction

Image-guided thermal ablations such as radiofrequency abla-

tion (RFA) and microwave ablation have emerged as attractive

minimally invasive interventional treatments of liver malig-

nancies, as first-line therapy and in patients ineligible for

surgery. Probes are percutaneously inserted into the tumour

B. J. J. Abdullah : C. H. Yeong

Department of Biomedical Imaging and University of Malaya

Research Imaging Centre, Faculty of Medicine,

University of Malaya, 50603 Kuala Lumpur, Malaysia

B. J. J. Abdullah (*) : C. H. Yeong : K. L. Goh

Department of Internal Medicine, Faculty of Medicine,



B. K. YoongDepartment of Surgery, Faculty of Medicine, University of Malaya,

50603 Kuala Lumpur, Malaysia

G. F. Ho

Department of Oncology, Faculty of Medicine,


C. C. W. Yim

Department of Anesthesia, Faculty of Medicine,


A. Kulkarni

Perfint Healthcare Corporation, Florence, OR 97439, USA

Eur Radiol

DOI 10.1007/s00330-014-3391-7

Clinical Publication - 2Clinical Publication - 2




and a volume of tissue is devitalized either by heat (using

radiofrequency or microwave) or freezing (cryoablation). Ac-

curate placement of the probe is critical to achieving not only

technical success (for lesions high in the dome or large lesions

requiring multiple overlapping ablations), but also vital in

ensuring adequate ablation margins to prevent local tumour recurrence [1]. Additionally, patient safety is compromised

with imprecise electrode placement, which may lead to major

complications such as pleural and gastrointestinal perfora-

tions, laceration of vessels with bleeding, or thermal collateral

damage with bile duct stenosis, biloma, gastrointestinal in-

flammation and subsequent perforation [2].

To improve trajectory planning and targeting, surgical nav-

igation systems have recently been adapted to the needs of

interventional radiology [3, 4]. The navigation systems (com-

monly known as “robots”) assist in either planning and plac-

ing of the needles/probes, or allow tracking the position of a

surgical tool that is projected in real-time in the patient ’s

corresponding computed tomography (CT) or magnetic reso-

nance (MR) images [5]. The aim of these CT or MR compat-

ible robots is to increase the accuracy of needle or probe

placement through three-dimensional (3D) imaging and com-

puterized trajectory planning in arbitrary orientated tracks, to

improve the outcomes of interventional therapies. Further-

more, in highly inaccessible lesions that require multiple plane

angulations, robotically assisted needle placement may im-

prove access to the target by allowing off-axial paths of needle

placement. Previous studies have confirmed high targeting

accuracy of a commercially available robot in phantom and

animal experiments [4], as well as in clinical settings [3, 5].

Reduction of exposure to radiation during CT fluoroscopy to

clinical staff and patient is another potential benefit [3]. Al-

though ultrasound-guidance provides a radiation-free environ-

ment and allows off-axial needle paths, it has several limita-

tions. These include ultrasound-occult lesions, difficulty in

visualizing deep lesions, shadowing artefacts caused by air,

bone or bowel, and increased operator variability.

The goal of our study was to evaluate the technical success,

radiation dose, ease of use and safety of a new commercially

available CT-guided robotic system, Maxio (Perfint

Healthcare, Florence, Oregon, USA), in assisting treatment

planning and tumour targeting for liver tumours ablative

therapy.

Materials and methods

This study has been granted with medical ethics approval

(MEC No. 949.9) from the Medical Ethics Committee,

University of Malaya Medical Centre, Kuala Lumpur,

Malaysia. Informed consent was obtained from all the

patients.

Patients

A total of 20 patients (40 lesions) with primary or secondary

liver tumours were treated with thermal ablative therapy

(August 2013 to February 2014) with the guidance of

the robotic needle positioning system, Maxio (Perfint Healthcare, Florence, Oregon, USA), attached to a CT fluo-

roscopy system (SOMATON Definition AS 128, Siemens

Healthcare, Munich, Germany).

Ten patients had new and recurrent hepatocellular carcino-

ma (HCC), while the other ten patients had liver metastases.

Twelve patients were treated with the RITA StarBurst radio-

frequency system (Angiodynamics, Latham, New York,

USA), three patients were treated with the Cool-tip RFA

system (Valleylab, Boulder, Colorado, USA), and the remain-

ing five patients were treated with the Avecure microwave

system (Medwaves, San Diego, California, USA). All the

lesions were less than 50 mm in maximum diameter

(the average dimension of the tumour was 19×23 mm).

Maxio robotic needle positioning system

Maxio is an image-guided, physician controlled stereotactic

accessory to a CT system, intended as an instrument guide for

the stereotactic spatial positioning to assist in manual advance-

ment of one or more needle-based devices for CT-guided

percutaneous procedures such as biopsy and RFA. The system

(Fig. 1) consists of a treatment planning workstation that is

compatible with 3D DICOM images and a robotic positioning

device docked on a registration plate (InstaRegTM, Perfint

Healthcare, Florence, Oregon, USA), as shown in Fig. 2,

adjacent to the CT table during the interventional procedure.

The robotic arm has five degrees of freedom to the point of

interest and is able to provide orbital, cranio-caudal angula-

tions or a combination of both for thoracic, abdominal and

pelvic interventional procedures.

Figure 3 demonstrates the operational flow of the Maxio

robotic system for interventional procedures.

Treatment planning and simulation

All the thermal ablation procedures were performed under

general anaesthesia. After intubation, the patients were

wrapped in reusable immobilisers to minimise patient move-

ment during the procedure. Following baseline CT with

suspended expiration, the lesions were identified. All the

patients had non-contrasted baseline CTs, except six patients

whose lesions were difficult to localize. The CT images were

then reconstructed to 1 mm thickness and transferred to the

Maxio workstation for simulation and treatment planning. The

application software allows 2D and 3D visualization of the

Eur Radiol




volumetric data. Once the volume of interest (VOI) was

identified, the tumour was segmented automatically by the

software to allow verification of the target volume (Fig. 4a ).

This is displayed in axial coronal and sagittal planes, together

with a 3D segmented image. Any deviation from the tumour

margins can be manually adjusted by either cropping or

adding to the target volume. The target point (centre of the

tumour volume) was then defined by the radiologist on the

treatment plan. The entry point (needle puncture site on the

skin surface) was determined by taking into consideration any

critical structures in the needle path. This was done byscrolling the axial images manually on the treatment plan

and ascertaining if the needle path traverses any critical struc-

tures, as the software is not able to reconstruct an obliquity to

see the entire needle path in one image. If critical organs were

involved, the entry point needed to be modified to change the

needle trajectory. The operator then input the choice of abla-

tion device (RFA or microwave), including the length of the

probe that was going to be used. The workstation determined

the orbital and cranio-caudal angulations as well as the min-

imum length of the probe required to complete the ablation

(refer to Fig. 4b). The system allows up to six probes to be

planned at one time. Figure 4c shows an example of treatment

plans for two different tumours. The simulated ablation maps

of different probes were then displayed as an overlay on the

original tumour volume, as shown in Fig. 4d. The plan was

carefully checked by the radiologist to avoid critical organs or bone across the trajectory prior to confirming the plan. If the

margins were inadequate, the target point or the entry point

could be modified.

Robotic-assisted needle placement

Once the treatment plan was confirmed, the patient was posi-

tioned at the exact coordinate as determined in the treatment

plan. The patient ’s skin in the intended region was prepared

for the procedure. The skin and liver capsule along the

projected path of the ablation probe was infiltrated with

10 ml of 1 % lignocaine. The robotic arm was then activated

and moved automatically to the desired location. Once the

robotic arm was completely halted at its position, the radiol-

ogist placed an appropriate bush (a plastic needle holder) that

had a diameter matching the diameter of the ablation probe at

the end-effectors of the arm. The function of a bush is to

minimize deviation of the needle entry point from the treat-

ment plan, by guiding the needle along the planned trajectory.

The radiologist then inserted the ablation probe through the

bush and generally deployed the probe completely (in one go)

to the end of the bush (Fig. 5). Upon completion of the

Fig. 1 Key components of the

Maxio robotic system

Fig. 2 InstaRegTM docking system for the Maxio. The alphabet “ R”

indicates that the robot is docking at the right side of the CT gantry at

which the tumour is more conveniently accessed from the right of the CT

Eur Radiol




insertion of the probe, the end effectors were detached from

the probe and the robotic arm was returned to its original

position.

A CT fluoroscopy check examination was performed to

ascertain the location of the ablation probe within the target

volume (Fig. 6). Ablation therapy was then started. For mul-

tiple lesions, the process of needle insertion was repeated as

determined by the treatment plan. The completeness of the

ablation was determined by using multiphasic contrast-enhanced CT immediately after the ablation (Fig. 7).

Patient respiratory motion control

To optimize tumour localization, the baseline CT, CT fluoros-

copy check and post-ablation contrast-enhanced CT were all

performed at the end expiration of the patient, with the airway

disconnected from the ventilator. To minimise liver and hence

ablation probe excursion between the end expiration (when

needle placement was carried out) and the inspiration, the tidal

volumes were set at a high respiratory rate and high O2 level

considered safe by the attending anaesthetist. Muscle relax-

ants were used regularly (especially when doing multiple

placements) to minimise spontaneous breathing of the patient

so that the end expiratory phases were consistent. Otherwise,

the loss of muscle paralysis would impair the end tidal volume

and place the liver at a much lower level.

Data collection and analysis

The orbital and cranio-caudal angulations of the robotic arm

were recorded for each lesion targeted in all patients. The

numbers of adjustment of the needle to achieve satisfactory

positioning within the desired tumour volume were docu-

mented. Deviations of the tip from the centre of the targeted

location were also recorded.

The performance level of the overall procedures was

assessed on a five-point scale (refer Table 1 for the description

of the scoring scheme) by the interventional radiologist for

Fig. 3 Operational flow of the Maxio robotic system for interventional procedures

Eur Radiol




each robotic-assisted thermal ablation. Any complications

related to the use of the robot or the procedures were also

recorded.

The CT fluoroscopic dose (DLP) received by the patients

during the probe placement and ablation was recorded. The

total CT dose from the whole procedure including the multi-

phasic CT studies was also recorded. The doses were then

compared with a random historical control group of 30 pa-

tients (48 lesions) who had liver radiofrequency or microwave

ablation performed by the same radiologist, but without using

the assistance of a robot for probe placement. Statistical anal-

ysis was performed using independent samples T-test with a

95 % confidence interval.

Results

Thermal ablation was successfully completed in 20 patients

with 40 lesions, and confirmed on multiphasic contrast en-

hanced CT. No complications related to either the use of the

robot or the thermal ablation were noted in this study. How-

ever, there was a single case of residual disease after the

ablation. Table 2 demonstrates patient demography and treat-

ment protocols for all the patients.

The total number of lesions treated in each session ranged

from one to a maximum of five lesions (mean of 2±1). The

deepest lesion was 169 mm, while the shallowest was 40 mm

from the skin’s surface. The diameter of the lesions ranged

Fig. 4 Treatment planning and simulation on the Maxio’s workstation. a

Identification and segmentation of the first lesion (labelled as Tumour 1).

The CT images are displayed in axial (middle panel ), coronal (top right

panel ) and sagittal (bottom right panel ) planes, while the 3D simulated

diagram is shown in theleft panelof thetreatment plan. b The entry point,

target point, type of probe and targeted ablation volume were defined by

the interventionalist in the treatment plan. The pink straight line indicates

the trajectory of the ablation probe from the skin surface (entry point ) to

the centre of the target volume (target point ). The ablation volume is

calculated automatically by the software and indicated in the treatment

plan (shown as green spheres covering the tumour). c Segmentation and

treatment planning for the second lesion (labelled as Tumour 2). The

same planning procedures as for Tumour 1 are repeated. The simulation

forTumour1 canstill be seen on theplan as reference. Theindigo straight

line indicates the trajectory of the ablation probe for the second lesion. d

A complete plan for all the three lesions targeted in the same patient. The

simulated needle trajectories are shown in the images and carefully

checked through by the interventionalist prior to the RFA procedures

Eur Radiol




from 5 to 49 mm (mean diameter 19×23 mm). The lesions

were all targeted successfully with the assistance of the robotic

device. The orbital angulations of the robotic arm ranged from

-49.4° to 65.1° (mean positive angulation was 25.1±17.8°;

mean negative angulation was -28.5±16.0°). The cranio-

caudal angulations remained 0° in 24 lesions (15 patients),

while the remaining 16 lesions (five patients) had cranio-

caudal angulations that ranged from −11.9° to 36.8°

(mean positive angulation was 4.3±8.4°; mean negative

angulation was −10.3±2.2°).

Readjustments of the probe were required in 12 of the 20

patients, with only a single repositioning in each of the lesions.

The average number of needle readjustment was 0.8±0.8.

There were no cases of needle reinsertions required. The mean

performance level rated for the robotic-assisted ablation pro-

cedure was 4.4±0.6.

The total DLP per patient for the entire robotic assisted

thermal ablation was 1382±536 mGy.cm, while the CT fluo-

roscopic dose per lesion was 352±228 mGy.cm. When com-

par ed with histori cal dat a from our stand ard abl ation

procedure without the assistance of the robotic device, the

total DLP per patient (n=30) was 1611±708 mGy.cm, while

the CT fluoroscopic dose per lesion was 501± 367 mGy.cm.

Although the dose reduction was not statistically significant

different ( p>0.05), the total DLP, and CT fluoroscopic dose

per lesion were reduced by 14 and 30 %, respectively. Table 3shows the comparison of patient radiation dose for robotic-

assisted versus non-robotic assisted thermal ablation

procedures.

Discussion

Percutaneous CT-guided intervention is an effective method

for image-guided biopsy and tumour ablation. However, the

accuracy of CT-guided needle or probe placement, which is

critical for good diagnostic yield, is highly dependent upon

physician experience. Additionally, the presence of vulnerable

anatomy (such as bowel, nerves or vessels in proximity to the

target) in the needle path has low tolerance for errors in needle

placement. With conventional techniques, challenging tumour

targeting frequently mandates multiple needle adjustments

and intra-procedural imaging, which can prolong procedure

duration as well as increase patient radiation exposure and

procedural risk [6, 7]. Recent advances in robotically guided

interventions have been successful in assisting placement of

needles or related instruments for surgery and interventional

procedures [8 – 13].

For small tumours, such as HCC that are <3 cm, RFA has

been shown to achieve results comparable to surgical resec-

tion. However, its efficacy is reduced for larger tumours [14,

15]. This may in part be attributable to the complexity of

multi-probe placement (simultaneous or sequential), which

is prone to human error, as well as the greater heat sink effect

with larger, more perfused tumours. Accurate probe place-

ment is thus critical for successful large volume composite

ablation and a tumour-free margin [1, 16].

Fig. 6 CT fluoroscopy check examination to verify the location of the ablation probe within the target volume for (a) Tumour 1 (b) Tumour 2

Fig. 5 The intervention radiologist inserted the RFA probe to the target

tumour through the bush located at the end-effector of the robotic arm

Eur Radiol




Navigational software and robotic assistance may offer a

tailored solution to physicians confronting a technically chal-

lenging biopsy or ablation target. Early phantom and clinical

experiences with robotic navigation systems suggest proce-

dural accuracy, reduced procedure time and reduced patient

radiation exposure compared with freehand techniques

[3, 4, 17].

The robot used in this study was a CT-compatible 3D

tumour targeting and needle positioning system for interven-

tional radiology procedures. It is an improved version of its

predecessor, ROBIO Ex (Perfint Healthcare, Florence,

Oregon, USA), which only allows 2D visualization of the

axial images and single needle or probe access per treatment

plan. Additionally, the planning software has a multiplanar

capability, ensuring that better delineation of the centre of the

lesion can be achieved. The system calculates coordinates on

DICOM images from the CT console and guides the

placement of the needle accurately within the body using a

stereotactic device. The depth of needle placement is pre-

determined by the system, but the operator still has the option

of varying this for increased safety. The system can be used for

tumour targeting for abdominal and thoracic interventions,

including biopsy, fine needle aspiration cytology (FNAC),

tumour ablation, pain management and drainage.

While MR-compatible robots have also been developed

and provide many advantages such as non-ionizing

multiplanar imaging with hepato-specific contrast agents and

have the highest liver tumour contrast compared to CT and

ultrasound, they are, however, expensive and require all MR-

compatible equipment and accessories. Hence, access may be

limited and the robots currently only useful for lesions that are

not accessible by other methods [18, 19].

Localisation and navigation systems performed with op-

tical or magnetic localisation spheres require multiple skin

markers to be broadly placed prior to imaging [20]. In

addition, pre-procedure import and processing of the 3D

data to the robot ’s workstation can be complex and time

consuming and occupy a lot of space in the operation room.

Devices that are time consuming in terms of pre-arrangement

and usage are economically unattractive and are therefore not

likely to be used in daily routine. In contrast, the Maxio

requires minimal effort to be mounted and registered to the

CT device using the InstaReg™ technology. The system is

motorised and can be operated by one person. These fea-

tures reduced the complexity of the robotic-guided proce-

dure. We found the overall satisfaction with the performance

of the system to be high. Furthermore, the planning software

on the Maxio system allows the segmentation of the tumour

and subsequent selection of the ablation probe (RFA or

microwave) with the pre-determined ablation volumes to

be overlaid on the target tumour. This adequacy of the

ablation can be checked in all three planes to determine

successful ablation. If this is found to be inadequate, the

tip of ablation needle can be repositioned or a different

probe selected.

Fig. 7 Comparison of (a) Pre-RFA contrast enhanced baseline CT; b

Post-RFA multiphasic contrast-enhanced CT. The ablated volume (red

dashed line) can be clearly seen on the multiphasic contrast-enhanced

scan to verifythe completeness of theablation; and(c) 3-month post-RFA

follow up showing reduction of the coagulation necrosis

Table 1 Scoring scheme for evaluation of the performance level of

robotic-assisted thermal ablation

Score Criteria

5 • Successful ablation

• No needle repositioning

• Superior to the manual needle insertion technique


• 1 to 2 needle repositionings

• Superior to the manual needle insertion technique


• 3 to 4 needle repositionings

• Equivalent to the manual needle insertion technique


• More than 4 needle repositionings or reinsertion of needle is

required

• Inferior to the manual needle insertion technique

1 • Ablation could not be completed due to needle positioning error

• Unsuccessful needle insertion

• Inferior to the manual needle insertion technique

Eur Radiol




T a b l e 2

P a t i e n t d e m o g r a p h y a n d t r e a t m e n t p r o t o c o l s o f t h e r o b o t i c - a s s i s t e d C T - g u i d e d t h

e r m a l a b l a t i o n f o r l i v e r t u m o u r s ( 2 0 p a t i e n t s , 4 0 l e s i o n s )

I D

A g e

S e x

D i a g n o s i s

T h e r m a l A b l a t i o n T r e a t m e n t

B

a s e l i n e c o n t r a s t - e n h a n c e d

C

T s c a n ( Y e s o r N o )

S i z e o f l e s i o n ( S h o r t

A x i s × L o n g A x i s )

D e p t h o f L e s i o n

f r o m t h e s u r f a c e

( m m )

A n g u l a t i o n s ( D e g r e e )

S h o r t a x i s ( m m ) L

o n g a x i s ( m m )

O r b i t a l ( + )

O r b i t a l ( − )

c c ( + )

1

7 4

M

L o w r e c t a l c a n c e r p o s t - a n t e r i o r r e s e c t i o n

w i t h l i v e r m e t a s t a s e s a t s e g m e n t s V ,

V I a n d V I

R F A u s i n g R I T A s y s t e m f o r

a l l t h e t u m o u r s

N

o

2 1

2

1

7 8

4 5 . 7

2 0

2

1

1 1 9

4 5 . 8

0 . 0

3 2

3

7

1 1 6

6 1 . 7

6 . 0

2

6 6

M

C o l o r e c t a l l i v e r m e t a s t a s e s a

t s e g m e n t s

V I I , I I , I I I a n d I



Y

e s

5

9

1 2 6

2 3 . 0

5 . 9

8

1

2

8 9

2 6 . 2

3 . 2

1 6

2

4

4 3

2 0 . 3

0 . 0

6

6

1 5 3

4 0 . 8

0 . 0

3

7 4

M


t

s e g m e n t s I I I

R F A u s i n g R I T A s y s t e m

Y

e s

2 1

2

1

1 2 2

2 3 . 3

0 . 0

4

5 6

M

H C C a t s e g m e n t I V a


N

o

1 6

2

0

7 7

2 9 . 3

9 . 7

5

6 4

M

H C C a t s e g m e n t s V I , V I I a n

d V I I I

R F A u s i n g C o o l - t i p s y s t e m

f o r a l l t h e t u m o u r s

N

o

2 7

3

5

1 1 6

2 2 . 8

0 . 0

2 3

2

9

1 5 2

4 4 . 7

0 . 4

2 1

4

3

1 0 4

3 5 . 8

0 . 0

6

6 1

M

H C C p o s t s e g m e n t a l h e p a t e c t o m y ,

n e w l e s i o n s a t s e g m e n t s I

V b a n d V I I I


f o r a l l t h e t u m o u r s

N

o

1 1

1

3

1 1 2

2 2 . 5

0 . 0

1 3

1

4

8 1

4 9 . 4

0 . 0

1 4

1

4

9 4

3 0 . 8

1 7 . 3

7

5 5

F

H C C a t s e g m e n t V I I


N

o

3 5

4

3

1 4 1

8 . 6

6 . 5

8

4 6

F

E n d o m e t r i a l c a r c i n o m a w i t h

l i v e r

m e t a s t a s e s a t s e g m e n t V I I


N

o

2 2

3

0

1 6 9

9 . 0

0 . 0

9

6 6

M


t s e g m e n t s

V , V I , I I X , I a n d I I

i . R F A u s i n g R I T A s y s t e m

f o r l e s i o n V , V I , I I X a n d I

i i . R F A u s i n g C o o l - t i p s y s t e m

f o r l e s i o n I I

Y

e s

1 9

2

3

7 1

5 . 5

0 . 0

1 5

2

1

1 1 2

2 1 . 0

2 5

3

0

1 2 8

2 4 . 9

0 . 0

2 1

2

2

5 3

3 0 . 6

0 . 0

1 6

2

0

1 0 8

2 4 . 7

0 . 0

1 0

6 6

M

R e c u r r e n t m u l t i c e n t r i c H C C

a t

s e g m e n t s I I I , V I a n d I I



Y

e s

1 1

1

5

7 9

3 9 . 9

0 . 0

3 2

3

8

1 0 5

6 . 8

3 . 3

1 0

1

1

1 2 8

1 . 8

0 . 0

1 1

4 1

F

B r e a s t m e t a s t a s e s t o t h e l i v e r a t

s e g m e n t s I I I , V I a n d V I I I



N

o

1 2

1

2

4 0

2 . 1

0 . 0

2 0

2

3

8 6

3 5 . 2

0 . 0

1 7

1

9

6 8

0 . 8

2 6 . 1

1 2

3 2

F

M u l t i p l e l i v e r m e t a s t a s e s f r o

m

g a s t r o i n t e s t i n a l s t r o m a l t u

m o u r

a t s e g m e n t s V I I a n d V / V I



N

o

2 0

2

3

5 2

8 . 6

0 . 0

1 9

2

1

9 9

2 9 . 9

2 0 . 2

1 3

8 0

F

L i v e r m e t a s t a s e s a t s e g m e n t s

V I I a n d I I I



N

o

1 3

1

4

1 1 7

2 5 . 6

0 . 0

1 2

1

4

1 2 6

0 . 0

3 6 . 8

8

9

7 3

4 8 . 2

0 . 0

1 4

6 0

F

L i v e r m e t a s t a s e s a t s e g m e n t

I V


N

o

2 5

4

2

1 0 4

3 6 . 0

1 1 . 7

1 5

4 6

M

H C C a t s e g m e n t V I / V I I

M i c r o w a v e a b l a t i o n u s i n g

A v e c u r e 1 4 G s i n g l e c y c l e

Y

e s

4 5

4

9

9 8

1 1 . 5

4 . 6

1 6

5 4

M

H C C a t s e g m e n t I I X / V I



N

o

2 6

3

8

9 2

2 0 . 4

0 . 0

1 7

5 6

F

H C C a t s e g m e n t I I I


N

o

1 0

1

3

4 7

2 . 2

0 . 0

1 8

5 3

M

H C C a t s e g m e n t s V I I / V I I I



N

o

2 8

3

2

8 8

1 . 7

1 2 . 8

Eur Radiol




T a b l e 2 ( c o n t i n u e d )

I D

A g e

S e x

D i a g n o s i s

T h e r m a l A b l a t i o n T r e a t m e n t

B

a s e l i n e c o n t r a s t - e n h a n c e d

C

T s c a n ( Y e s o r N o )

S i z e o f l e s i o n ( S h o r t

A x i s × L o n g A x i s )

D e p t h o f L e s i o n

f r o m t h e s u r f a c e

( m m )

A n g u l a t i o n s

( D e g r e e )

S h o r t a x i s ( m m ) L

o n g a x i s ( m m )

O r b i t a l ( + )

O r b i t a l ( − )

c c ( + )

1 9

6 0

F

C o l o r e c t a l l i v e r m e t a s t a s e s

a t s e g m e n t I I I



N

o

1 6

1

8

1 0 8

6 5 . 1

0 . 0

2 0

7 1

M

H C C a t s e g m e n t V



Y

e s

2 2

2

3

8 6

4 4 . 1

0 . 0

M e a n

1 9

2 3

9 9

2 5 . 1

2 8 . 5

4 . 3

S t a n d a r d D e v i a t i o n

8

1 1

3 1

1 7 . 8

1 6 . 0

8 . 4

M i n

5

6

4 0

0 . 0

0 . 8

0 . 0

M a x

4 5

4 9

1 6 9

6 5 . 1

4 9 . 4

3 6 . 8

I D


N u m b e r o f

N e e d l e

I n s e r t i o n s

N u m b e r o f

R e p o s i t i o n i n g /

R e a d j u s t m e n t

P e r f o r m a n c e

L e v e l ( 1

t o 5 , r e f e r t o s c o r i n g

s c h e m e i n T a

b l e 1 )

C T F l u o r o s c o p i c D o s e

( D L P , m G y . c m )

T o t a l C T D o s e

( C T D I v

o l

,

m G y )


( D L P , m G y . c m )

C T F l u o r o s c o p i c

D o s e ,

D L P

p e r L e s i o n

( m G y . c m )

O u t c o m e s

c c ( − )

1

1 1 . 9

3

1

4

1 0 8 3

7 5 3

1 8 6 0

3 6 1

S u c c e s s f u l a b l a t i o n

2

4

2

4

1 7 1 2

1 1 8 9

2 0 8 4

4 2 8


3

1

0

5

7 7 7

5 4 0

1 1 9 1

7 7 7


4

1

0

5

1 8 7

1 7 0

1 2 1 8

1 8 7


5

3

1

4

4 9 5

3 4 4

1 4 5 8

1 6 5


6

3

1

4

8 7 5

6 0 8

1 0 3 0

2 9 2


7

1

0

5

1 6 4

1 1 4

8 1 5

1 6 4


8

1

1

4

6 1 4

4 2 6

1 7 2 5

6 1 4


9

5

3

3

1 5 9 7

1 1 0 9

2 6 9 9

3 1 9


8 . 8

Eur Radiol




T a b l e 2 ( c o n t i n u e d )

I D


N u m b e r o f

N e e d l e

I n s e r t i o n s

N u m b e r o f

R e p o s i t i o n i n g /

R e a d j u s t m e n t


L e v e l ( 1

t o 5

, r e f e r t o s c o r i n g

s c h e m e i n T a

b l e 1 )

C T F l u o r o s c o p i c D o s e

( D L P , m G y . c m )


( C T D I v

o l

,

m G y )


( D L P , m G y . c m )


D o s e , D L P

p e r L e s i o n

( m G y . c m )

O u t c o m e s

c c ( − )

1 0

3

1

4

7 1 7

4 9 8

2 0 4 2

2 3 9


0 . 0

1 1

3

1

4

4 6 1

3 2 0

9 6 9

1 5 4


1 2

2

2

4

1 4 4 6

1 0 0 5

1 9 9 6

7 2 3


1 3

3

0

5

1 1 3 6

7 8 9

1 5 5 4

3 7 9


1 4

1

1

4

2 8 4

1 9 7

8 1 1

2 8 4


1 5

1

1

4

1 2 8

8 9

8 5 1

1 2 8


1 6

1

0

5

7 2 9

5 0 8

1 1 4 2

7 2 9


1 7

1

1

4

5 8 9

1 3 1 2

7 0 1

5 8 9


1 8

1

0

5

4 5

3 1

1 0 1 8

4 5


1 9

1

0

5

4 1 8

2 9 0

1 0 8 0

4 1 8


2 0

1

0

5

5 4

3 7

1 3 9 1

5 4


M e a n

1 0 . 3

2 . 0

0 . 8

4 . 4

6 7 6

5 1 7

1 3 8 2

3 5 2


2 . 2

1 . 3

0 . 8

0 . 6

5 0 5

3 9 6

5 3 6

2 2 8

M i n

8 . 8

1

0

4

5 4 5

3 1

7 0 1

4 5

M a x

1 1 . 9

5

3

5

1 7 1 2

1 3 1 2

2 6 9 9

7 7 7

F = F e m a l e ; M = M a l e ; H C C = H e p a t o c e l l u l a r c a r c i n o m a ; R F A = R a d i o f r e q u e n c y a b l a t i o

n ; C C = C r a n i a l - c a u d a l a n g l e ; M i n = M i n i m u m ; M a x = M a x i m u m

Eur Radiol




As was previously reported [3], the greater control and ease

of needle placement outside the bore of the CT gantry without

exposure to CT fluoroscopy dose was again a tremendous

benefit. This is especially helpful in patients who are large,

as well as for the lesions that require more lateral access of the

needle. Even though none of the patients in this study required

placement of multiple probes simultaneously, we believe this

system will be truly beneficial when multiple probes/needles

are necessary for the treatment, e.g., Cool-tip RFA needles

with a switching controller. Additionally, robotic-assisted in-

terventions would be useful for those who do not have access

to CT fluoroscopy during the procedures.

Although our study showed no significant differences of

patient radiation dose between robotic-assisted and conven-

tional thermal ablation, this may be related to the expertise of

the operator in this study. Previous studies noted the decreased

accuracy of inexperienced operators when placement of the

needles was performed manually under the guidance of CT

fluoroscopy [21, 22]. Certain impreciseness during manual

needle insertion is unavoidable. The continuous reassessment

and repetitive adjustment of the needle orientation under the

guidance of CT fluoroscopy could lead to an increase in

radiation exposure to the patients as well as the attending staff.

With the assistance of the robotic positioning device, the direct

radiation exposure to the interventionist ’s hands during needle

insertion could be minimized. The radiation exposure to the

operators was not assessed in this study, but theoretically the

staff dose decreases when the CT fluoroscopy dose decreases.

A randomised controlled study with a larger sample size

would be necessary to confirm this.

A critical part of the capability of the Maxio system is in

ensuring accurate co-registration of the planning data sets with

liver volume at the time of needle insertion, as the system is

still not able to compensate for movements of the target

region, especially those caused by respiration, since the

planned trajectory is based on a static-acquired 3D data set.

This co-registration in our practice was achieved by

performing all procedures under general anaesthesia with

intubation and muscle relaxants at the end of expiration, with

the airway disconnected from ventilator-produced consistent

positing. The muscle relaxants were used regularly, especially

when doing multiple placements. Otherwise, the loss of mus-

cle paralysis would impair the end tidal volume and place the

liver at a much lower level. The baseline CT, needle placement

and post-procedure CT acquisitions were all performed at the

end of expiration once the ventilator was disconnected. Others

have suggested that anaesthetic manoeuvres, such as high

frequency jet ventilation to reduce respiratory motion, signif-

icantly reduce radiation dose [23]. However, these systems are

expensive and require a greater skill set. Additionally, we used

low tidal volumes with high respiratory rate and high O2 to

minimize liver excursion and needle movement in the cranio-

caudal direction.

The use of robots to assist in thermal ablation may require a

major change to the current workflow, with additional steps to

the procedure. These include docking the robotic system,

importing the images from the CT console into the worksta-

tion, segmenting the tumour, planning the entry and target

points, inputting the length of the needle, and finally sending

the information to the robotic arm. Thus, there would be a

need to redefine the roles of different members of the medical

team with use of robotic assisted thermal ablation. A compre-

hensive work flow chart, with staff being well trained in

operating the robot, also needs to be established.

In conclusion, we present our early clinical experience of

thermal ablation for primary and secondary liver tumours

using an advanced CT-guided robotic system. The system

showed good accuracy for percutaneous needle placement

for ablative therapy, with a radiation dose comparable to the

historical controls. Even though these preliminary data were

promising, the study was not randomised. A randomised

controlled study with a larger sample size comparing robotic

and non-robotic-assisted thermal ablation needs to be carried

out to determine the outcomes.

Acknowledgements The scientific guarantor of this publication is

Basri Johan Jeet Abdullah. The authors of this manuscript declare rela-

tionships with the following companies: Perfint Healthcare Pvt Ltd,

Florence, Oregon, USA. The authors state that this work has not received

any funding. No complex statistical methods were necessary for this

paper. Institutional Review Board approval was obtained. Written in-

formed consent was obtained from all subjects (patients) in this study.

Approval from the institutional animal care committee was not required

because no animal was used in this study. Some study subjects or cohorts

have been previously reported in the European Congress of Radiology

(ECR), Vienna, on 6 March 2014. Methodology: prospective, case-

control study, performed at one institution.

Table 3 Comparison of total

DLP per patient and CT fluoro-

scopic dose per lesion of robotic-

assisted versus non-robotic-

assisted thermal

ablation procedures

Robotic-assisted

thermal ablation

(n=20)

Non-robotic-assisted

thermal ablation

(control group, n=30)

Dose reduction

with robotic

assistance (%)

P -value

Total DLP per patient (mGy·cm) 1382 ±536 1611 ±708 14 P >0.05

CT fluoroscopic dose per lesion(DLP, mGy·cm)

352±228 501±367 30 P >0.05

Eur Radiol




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Eur Radiol




INTERVENTIONAL

Robot-assisted radiofrequency ablation of primary

and secondary liver tumours: early experience

Basri Johan Jeet Abdullah & Chai Hong Yeong &

Khean Lee Goh & Boon Koon Yoong & Gwo Fuang Ho &

Carolyn Chue Wai Yim & Anjali Kulkarni

Received: 22 May 2013 /Revised: 1 July 2013 /Accepted: 10 July 2013# The Author(s) 2013. This article is published with open access at Springerlink.com

Abstract

Objective Computed tomography (CT)-compatible robots,

both commercial and research-based, have been developedwith the intention of increasing the accuracy of needle place-

ment and potentially improving the outcomes of therapies in

addition to reducing clinical staff and patient exposure to

radiation during CT fluoroscopy. In the case of highly inac-

cessible lesions that require multiple plane angulations, robot-

ically assisted needles may improve biopsy access and

targeted drug delivery therapy by avoidance of the straight

line path of normal linear needles.

Methods We report our preliminary experience of performing

radiofrequency ablation of the liver using a robotic-assisted

CT guidance system on 11 patients (17 lesions).

Results/Conclusion Robotic-assisted planning and needle

placement appears to have high accuracy, is technically easier

than the non-robotic-assisted procedure, and involves a sig-nificantly lower radiation dose to both patient and support

staff.

Key Points

• An early experience of robotic-assisted radiofrequency ab-

lation is reported

• Robotic-assisted RFA improves accuracy of hepatic lesion

targeting

• Robotic-assisted RFA makes the procedure technically easier

with significant lower radiation dose

Keywords Robot . Radiofrequency ablation . Liver tumour .

CT-guided . Interventional radiology

Introduction

Computed tomography (CT)-compatible robots have been

developed and may soon be integrated into CT-guided renal

mass ablation, hopefully reducing the radiation exposure to

clinical staff and patients during CT fluoroscopy [1]. One

recent study compared a preoperative computer-assisted opti-

cal needle tracking navigation system (KOELIS®, Medtech

Inc, Grenoble, France) with a CT-mounted robotic needle

driver system (AcuBot®, Johns Hopkins University, Balti-more, MD, USA) and found improved accuracy (mean target

distance 1.2 versus 5.8 mm, P <0.0001) and reduced targeting

time (37 versus 108 s, P <0.0001) for the CT-mounted robotic

needle driver system [2]. The authors demonstrated the po-

tential of robotic needle guidance to improve needle interven-

tions, demonstrating superiority over a commercial navigation

system.

Even newer robotic-based image-guided procedures are in

development including specialised robotically controlled

“steerable” needles that may allow for access to previously

B. J. J. Abdullah (*)Department of Biomedical Imaging, Faculty of Medicine, Universityof Malaya, 50603 Kuala Lumpur, Malaysia e-mail: [email protected]

C. H. YeongUniversity of Malaya Research ImagingCentre, Faculty of Medicine,University of Malaya, Kuala Lumpur, Malaysia

K. L. GohDepartment of Internal Medicine, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia

B. K. YoongDepartment of Surgery, Faculty of Medicine, University of Malaya,50603 Kuala Lumpur, Malaysia

G. F. HoDepartment of Oncology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia

C. C. W. YimDepartment of Anesthesia, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia

A. KulkarniPerfint Healthcare Corporation, Florence, OR 97439, USA

Eur Radiol

DOI 10.1007/s00330-013-2979-7





inaccessible anatomical structures for improved biopsy access

and targeted drug delivery therapy by avoidance of the straight

line path of normal linear needles [3]. The increasing com-

plexity invariable leads to increased cost of the devices and

there is a need to balance these conflicting aims.

We report our preliminary experience with a CT or PET-CT-guided robotic positioning system (ROBIO™ EX, Perfint

Healthcare Pvt. Ltd, Florence, OR, USA), which is designed

to assist interventional radiologists in performing procedures

that require precise tool positioning. ROBIO™ E X is a

standalone positioning device that can be moved to the desired

position along the patient table of the CT system. This device

has two linear motions to position the guide to the point of

interest and two angular motions to facilitate the angular entry

of the needle. The system offers several features to help

clinicians to target the tumour and plan for accurate tool

placement. It facilitates targeting and tool placement in deep-

seated lesions requiring orbital, cranio-caudal angulations or a combination of both for thoracic, abdominal and pelvic inter-

ventional procedures.


This study was granted with medical ethics approval (MEC

no. 949.9) from the Medical Ethics Committee, University of

Malaya Medical Centre, Kuala Lumpur, Malaysia.

Patients

A total of 11 patients with 17 lesions were treated with

radiofrequency ablation (RFA) with the guidance of the

ROBIO™ EX (Perfint Healthcare Pvt. Ltd, Florence, OR,

USA). Six patients had new and recurrent hepatocellular

carcinoma (HCC) and 5 patients had colorectal metastases.

Eight patients were treated with the Cool-tip RFA system

(Valleylab, Boulder, CO, USA) and 3 patients were treated

with the RITA StarBurst® system (Angiodynamics, Latham,

NY, USA). All the lesions were no greater than 3.0 cm in

maximum diameter (the average dimension of the tumour was

2.0×2.2 cm).

All the RFA procedures were performed under general

anaesthesia. Once the patients were intubated, they were

wrapped in reusable immobiliser to minimise patient move-

ment during the procedure. In order to optimise needle place-

ments, the baseline CT, verification of needle placement and

post-procedure CT were performed at end expiration with the

airway disconnected from the ventilator. Additionally, to min-

imise liver excursion between the end expiration (when needle

placement was carried out) and the inspiration, the tidal vol-

umes were set at low with high respiratory rate and high O2

level. Further, to ensure that spontaneous breathing of the

patient would not affect the end expiratory phase, we used

muscle relaxants regularly especially when doing multiple

placements. Otherwise the loss of muscle paralysis would

impair the end tidal volume and place the liver at a much

lower level.

All the patients had non-contrast baseline CT to identify the

lesions. However in 6 patients, because the lesions were small,contrast-enhanced CT studies (example shown in Fig. 1a )

were performed as the baseline to better delineate the location

of the lesions. Post-RFA three-phase CTs (Fig. 1d) were then

performed to assess the completion of the ablation as well as

to act as the baseline for subsequent follow-up. One patient,

however, did not have post-RFA CT because of renal

impairment.

ROBIO™ EX treatment planning

Following baseline CT, the lesions were identified. The CTimages were exported to the ROBIO™ EX workstation for

treatment planning. The target point (centre of the tumour

volume) as well as the entry point (needle puncture site on

skin surface) was determined by the interventional radi-

ologist. The angulations of the needle, the depth of the

lesion as well as the needle trajectory path were calcu-

lated by the ROBIO™ EX workstation and shown on

the treatment plan (Fig. 1b). The plan was carefully checked

by the radiologist to avoid critical organs or bone across the

trajectory. Once confirmed, the plan was sent to the robotic

arm for execution.

Robotic-assisted needle placement

Once the treatment plan was confirmed, the patient was posi-

tioned to the exact coordinates as shown in the ROBIO™ EX

treatment plan. The patient ’s skin was prepared for the proce-

dure in the intended region. The robotic arm was then activat-

ed and it moved automatically to the planned coordinates as

determined in the treatment plan. Once the robotic arm was

completely halted at its position, the radiologist placed an

appropriate bush and bush holder at the end-effector of the

arm (Fig. 2). The skin and liver capsule along the projected

path of the RFA needle were infiltrated with 10 mL of 1 %

lignocaine. The radiologist then inserted the RFA needle

through the bush and pushed the needle to the predetermined

depth where the end-effector was located (Fig. 3). Upon

completion of the insertion of the RFA needle, the robotic

arm was detached from the needle and returned to its original

position. CT fluoroscopy (Fig. 1c) was performed to ensure

that the RFA needle was located within the tumour volume.

RFA therapy was then started and the completeness of the

ablation was determined by using multiphasic contrast-

enhanced CT immediately after the RFA.

Eur Radiol




Data collection and analysis

The orbital and cranio-caudal angulations of the robotic arm

were recorded for each lesion targeted in all patients. The

number of adjustments of the RFA needle was documented.

Deviation of the tip from the centre of the targeted locationwas recorded.

The performance level of the overall procedures was assessed

by the interventional radiologist for each robotic-assisted RFA

on a five-point scale (5=excellent, 4= good, 3 =average, 2 =fair

and 1=poor). Any complications related to the use of the robot

or the RFA were also recorded.

The CT fluoroscopic dose (DLP) received by the patients

during the needle placement and ablation was recorded. The

total dose from the whole procedure including the multiphasic

CT studies was also recorded as the CTDIvol. The doses were

then compared with a random historical control group of pa-

tients who had liver RFA performed by the same radiologist but

without using the assistance of a robot for needle placement.

Results

Radiofrequency ablation was successfully completed in 11

patients with 17 lesions. The deepest lesion was 13.7 cm and

the shallowest was 6.2 cm from the skin surface. The diameter

of the lesions ranged from 1.1 to 3.0 cm. The lesions were all

targeted successfully with the assistance of a robot. No repo-

sitioning of the needle was required in any of the patients. The

orbital angulations of the robotic arm ranged from −49.0° to

46.5° (mean negative angulation was −26.5±24.9°; mean

positive angulation was 27.3± 12.0°). The cranio-caudal an-

gulations remained at 0° in 9 lesions (6 patients) whereas the

remaining 8 lesions (3 patients) had cranio-caudal angulations

of up to 25.0° (mean 7.4±9.9°).

Readjustments of the RFA needle were necessary in

6 lesions, with single readjustment in 4 lesions and two

readjustments in the remaining 2 lesions.

The total DLP and CTDIvol dose for the entire procedure

were 956.09±400.33 mGy cm and 258.00±125.46 mGy, re-

spectively. Compared with historical data from our standard

RFA procedure (n=30), the total DLP and CTDIvol dose were

1,703.93±1,152.37 mGy cm and 632.73±503.06 mGy,

respectively.

All patients had successful ablation confirmed on multi-

phasic contrast-enhanced CT except in one patient who had

renal impairment, which precluded contrast injections.

Post-RFA contrast-enhanced CT was performed in all ex-

cept one patient owing to renal impairment. The CT images

showed successful ablation of the targeted lesions in all pa-

tients. No complications related to either the robot or the RFA

were noted in this study.

The mean performance level rated for the robotic-assisted

RFA procedure was 4.6±0.5, in which the score 5 was

achieved in 7 patients and the score 4 was achieved in the

remaining 4 patients. The patients’ demography, treatment

protocols, radiation dose and evaluation of treatment outcomes

are summarized in Table 1.

Discussion

Image guidance techniques have revolutionised the perfor-

mance of interventions in medicine developed from the use

of advanced imaging investigations. These developments

have been adapted for neurosurgery, orthopaedic procedures,

urological surgery, etc. Current research into the combined

application of image-guided surgery and robots with the com-

plexities of soft tissue registration, operative navigation and

surgical use presents unique engineering challenges and new

knowledge requirements for interventional radiology.

Recent advances in robotically guided interventions have

been successful in assisting placement of needles or related

instruments for surgery or interventional procedures [4 – 9].

Magnetic resonance imaging (MRI)-compatible robots have

also been developed despite their significant engineering chal-

lenges and are continuing to be investigated for prostate biopsy

utilising the potential advantages of multiparametric MRI.

There may also be a future role for improving the accuracy

and precision of radioactive seed placement for prostate can-

cer using the interventional robotic device [10].

The robot used in this study was a CT- or PET-CT-guided

needle positioning system for interventional procedures. The

system calculates coordinates on DICOM images from CT or

PET-CT and guides the placement of the needle accurately

within the body using a robotic arm. The depth of needle

placement is pre-determined by the system but the operator

still has the option of varying this for increased safety. The

system can be used for tumour targeting for abdominal and

thoracic interventions, including biopsy, fine needle aspiration

cytology (FNAC), pain management, drainage and tumour

ablation.

Earlier robotic guidance devices required extensive instal-

lation and were often cumbersome and occupied a lot of space

in the operation room [6, 11, 12]. Devices that are time

consuming in terms of pre-arrangement and usage are eco-

nomically unattractive and are therefore not likely to be used

in daily routine. ROBIO™ EX requires minimal effort to be

mounted and registered to the CT device using the InstaReg™

technology (Perfint Healthcare Pvt Ltd., Florence, OR, USA).

The system is motorised and can be operated by one person.

These features reduced the complexity of the robotic-guided

procedure.

Localisation and navigation of the robots are usually

performed with optical or magnetic localisation spheres,

Eur Radiol




requiring a pre-procedure import and processing of the 3D

data to the robot ’s workstation, which can be a complex and

time-consuming procedure. However in our preliminary ex-

perience with the Robio™ EX, we found the overall satisfac-

tion with the performance to be high. Even though the plan-

ning did take time, it was found to be intuitive and this

increased time was compensated for by greater speed and

accuracy in placing the RFA needles.

Most importantly, the greater control and ease of needle

placement outside the bore of the CT gantry without exposure

to ionising radiation was a tremendous benefit. Both before and

during the needle insertion, neither direct exposure of the inter-

ventionist ’s hands to the radiation beam was involved, nor was

the use of inaccurate holding devices such as forceps necessary.

During the conventional CT-guided RFA procedure, insertion

and placement of the RFA needle are performed manually under

the guidance of real-time CT fluoroscopy. This challenging

procedure needs to be performed by an experienced interven-

tional radiologist and certain impreciseness during the manual

insertion is unavoidable. The continuous reassessment and re-

petitive corrections of the needle orientation under the guidance

of CT fluoroscopy could lead to an increase in radiation expo-

sure to the patients as well as the attending staff. Our study

showed a significant reduction of CT fluoroscopic dose in

patients of 43.9 % (DLP) and 59.2 % (CTDIvol) comparing

robotic and non-robotic-assisted RFA for HCC. This compari-

son might be biased because the radiation dosimetry data for

conventional RFA were collected from our historical HCC

patients in our hospital database. Further the interventional radi-

ologist who participated in this study was aware of the objec-

tive of dose assessment; therefore, there might be unintended

biasness in reducing the fluoroscopic dose. A randomised

controlled study with a larger sample size would be necessary

to confirm this.

Fig. 1 a Contrast-enhanced

baseline CT image shows solitary

colorectal metastases (26.2 mm

diameter) in segment VI. b

Reconstructed CT images (slice

thickness 1 mm) were sent to the

ROBIO™

EX workstation for treatment planning. The

simulated needle trajectory path

was shown on the treatment plan

and verified by the radiologist. c

A CT fluoroscopy check was

carried out to verify the accuracy

of theneedle placement withinthe

target volume. d Post-RFA three-

phase CTs to assess the

completeness of tumour ablation

Fig. 2 The robotic arm was positioned automatically to the exact coor-

dinates according to the treatment plan. The bush and bush holder were

clamped firmly at the end-effector of the robotic arm before insertion of

the RFA needle through the bush

Eur Radiol




Although we did not specifically measure the set-up time in

the patients treated, the interval between docking the device

until it was finally attached and powered up was less than

5 min. The time until the acquisition and planning were

completed took an average of another 10 min. Although there

is an initial set-up time for the robot and planning, this can be

compensated for by reduced need (or time) of needle reposi-

tioning using the manual method. Future analysis is proposed

to evaluate the time efficiency of the whole procedure.

We worked closely with anaesthetists in this study to opti-

mise needle placements. It was noted that performing all proce-

dures at the end of expiration with the airway disconnected from

ventilator produced consistent positing. Additionally using low

tidal volumes with high respiratory rate and high O2 was useful

to minimise liver excursion and needle movement in the cranio-

caudal direction. Further to ensure that spontaneous breathing of

the patient would not affect the end expiratory phase, we

ensured that muscle relaxants were used regularly especially

when doing multiple placements. Otherwise the loss of muscle

paralysis would impair the end tidal volume and place the liver

at a much lower level. The baseline CT, needle placement and

post-procedure CT acquisitions were all performed at the end of

expiration once the ventilator was disabled. Others have

suggested that anaesthetic manoeuvres, such as high frequency

jet ventilation, to reduce respiratory motion significantly reduce

radiation dose [13]. However these systems are expensive and

require a greater skill set.

There was no multiplanar capability of the current ROBIO™

EX system and thus determining the centre of the lesion usingaxial imaging may be limited. Also if there is more than a single

lesion, the operator needs to plan the subsequent treatments one

at time. Besides, the guidance software is also yet to compensate

for movements of the target region, especially those caused by

respiration as the planned trajectory is based on a static-acquired

3D data set. As the procedure was performed on patients under

arrested end expiration we were able to achieve more consistent

locations of the target lesions and hence accurate deployment of

the needles and measuring of the outcomes. The use of the

breath-holding systems to “fix” the location of the lesions to a

pre-determined point requires that the patients fully understand

and are able to cooperate completely with the requirements.

This would also add to the time required for training of the

patients before the actual procedure.

In addition, the use of robotic-assisted RFA may require a

change to the current workflow. Although it adds more steps to

the procedure (mainly done by the technician for device setup)

it does not bring any significant change in the clinical workflow

of the clinician. With free-hand CT-guided procedures, once the

studies have been viewed, the patient position can be deter-

mined. The radiographer would have done the baseline CT and

the physician would decide the best approach. Once that was

done the physician would localise the entry point using a laser

and under fluoroscopic guidance the procedure would be over

in less than 10 min in most circumstances. With the robot there

are several additional steps, which include docking the robotic

system, importing the images into the workstation, planning the

entry and target points, inputting the length of the needle, and

finally sending the information to the robotic arm. The robotic

arm would then move automatically to the accurate target

position for needle insertion. As a result, there would be a need

to redefine the roles of different members of the medical team

and the work flow chart. Also, the staff needs to being well

versed with the robot and its operation.

In conclusion, we present our early experience of robotic-

assisted CT-guided RFA for both primary and secondary liver

tumours. We have been able to show that the automated

system works well and could provide technical and diagnostic

success rates similar to those obtained with the manual meth-

od. Also, we found that the automated device decreased the

number of needle position adjustments and thereby minimised

the procedure time. The robotic device showed good accuracy

for percutaneous needle placement for RFA therapy with a

lower radiation dose compared with historical controls. From

our preliminary study we found that the robot provides high

accuracy with only a few readjustments required. Even though

these preliminary data were promising, the study was not

Fig. 3 The RFA needle was inserted by the radiologist through the bush

andthe bush holder. The needlewas then pushed to thepredetermined depth

where the end-effector of the robotic arm was located. The robotic arm was

then detached from the RFA needle to allow a CT check of positioning

Eur Radiol




T a b l e 1

P a t i e n t d e m o g r a p h y a n d p e r f o r m a n

c e e v a l u a t i o n o f t h e r o b o t i c - a s s i s t e d C T - g u i d e d r a d i o f r e q u e n c y a b l a t i o n ( R F A ) f o r h e p a t o c

e l l u l a r c a r c i n o m a ( H C C ) ( 1 1 p a t i e n t s ,

1 7 l e s i o n s )

I D

A g e

S e x

D i a g n o s i s

R F A t r e a t m e n t

B a s e l i n e

c o n t r a s t -

e n h a n c e d

C T

S i z e o f

l e s i o n s

( s h o r t a x i s

× l o n g a x i s )

D e p t h o f

l e s i o n s f r o m

t h e s u r f a c e

( m m )

A n g u l a t i o n s ( ° )

N u m b e r

o f n e e d l e

i n s e r t i o n

N u m b e r o f

r e p o s i t i o n i n g /

r e a d j u s t m e n t


l e v e l ( 5 – 1 :

e x c e l l e n t –

p o o r )


d o s e ( D L P ,

m G y c m )

T o t a l

C T d o s e

( C T D I v o l ,

m G y )

T o t a l C T

D o s e ( D L P

,

m G y . c m )

O u t c o m e s

S h o r t

A x i s

( c m )

L o n g

A x i s

( c m )

O r b

i t a l

( + )

O r b i t a l

( − )

C C ( + )

C C ( − )

1

6 4

F

C o l o r e c t a l

m e t a s t a s e s i n

s e g m e n t s V I I

R I T A 3 c y c l e s

a t

4 c m

d e p l o y m e n t

Y e s

1 . 5

2 . 3

1 2 2

4 0 . 5

2 0 . 0

1

0

4

3 3 1

2 2 9

9 6 1

S u c c e s s f u l

a b l a t i o n

2

4 2

M

R e c u r r e n t H C C

i n s e g m e n t s

I V & I

C o o l - t i p S i n g l e

c y c l e o f

8 m i n e a c h

Y e s

1 . 1

1 . 6

7 1

4 6 . 5

7 . 2

2

1

5

4 1 1

2 8 5

1 , 0 3 4

S u c c e s s f u l

a b l a t i o n

1 . 3

1 . 5

1 8 . 3

1 2 . 1

3

8 0

M

C o l o r e c t a l

m e t a s t a s e s i n

s e g m e n t I & I I


c y c l e 1 2 m i n

Y e s

1 . 5

1 . 6

8 1

6 . 0

0 . 0

2

0

5

2 4 1

1 6 7

9 4 2

S u c c e s s f u l

a b l a t i o n

1 . 2

1 . 0

2 9 . 0

0 . 0

4

7 3

F

H C C s e g m e n t V I C o o l - t i p S i n g l e

c y c l e 8 m i n

N o

2 . 1

2 . 1

8 1

1 5 . 0

0 . 0

1

0

5

2 2 3

1 5 6

3 6 9

N o C E b e c a u s e

p a t i e n t h a s

r e n a l

i m p a i r m e n t

5

5 7

M

H C C s e g m e n t

V I I


c y c l e 8 m i n

N o

1 . 6

1 . 9

7 3

1 9 . 0

0 . 0

1

0

5

3 4 4

2 3 8

9 4 1

S u c c e s s f u l

a b l a t i o n

6

5 9

M

C o l o r e c t a l

m e t a s t a s i s

s e g m e n t V I


c y c l e 1 2 m i n

Y e s

2 . 7

3

1 3 7

3 1 . 0

0 . 0

1

1

5

2 4 4

1 6 9

1 , 1 7 2

S u c c e s s f u l

a b l a t i o n

7

7 6

M

M u l t i c e n t r i c

H C C


c y c l e 1 2 m i n

Y e s

3 . 0

3

9 5

2 4 . 0

0 . 0

4

1

4

7 3 6

5 1 6

1 , 4 5 7

S u c c e s s f u l

a b l a t i o n

2 . 4

2 . 4

1 0 4

− 4 . 0

2 4 . 0

2 . 2

2 . 3

1 1 0

− 6 . 0

2 5 . 0

8

5 6

M

C o l o r e c t a l

m e t a s t a s e s

R I T A t o 5 c m

Y e s

2 . 7

2 . 7

1 0 8

− 4 7 . 0

2 4 . 0

1

0

5

5 9 2

2 6 2

9 6 9

S u c c e s s f u l

a b l a t i o n

9

7 3

M

C o l o r e c t a l

m e t a s t a s e s

R I T A t o 5 c m

Y e s

2 . 1

2 . 1

1 3 6

2 4 . 0

1 1 . 0

2

2

4

5 9 1

4 7 1

1 , 6 4 7

S u c c e s s f u l

a b l a t i o n

1 . 7

2 . 2

6 2

3 2 . 0

0 . 0

0

1 0

7 2

M

H C C

C o o l - t i p f o r

1 2 m i n c y c l e

e a c h

N o

2 . 2

2 . 7

9 5

− 4 9 . 0

0 . 0

2

1

5

2 9 8

2 0 6

7 1 6

S u c c e s s f u l

a b l a t i o n

1 . 7

2 . 6

1 3 3

− 2 . 0

0 . 0

1 1

4 3

M

H C C

C o o l - t i p t o

1 2 m i n

N o

2 . 1

2 . 1

7 5

4 2 . 0

3 . 0

1

2

4

2 0 0

1 3 9

3 0 9

S u c c e s s f u l

a b l a t i o n

A v e r a g e

1 . 9 5

2 . 1 8

9 8 . 9

2 7 . 3

− 2 6 . 5

7 . 4

4 . 6

3 8 2 . 8 2

2 5 8 . 0 0

9 5 6 . 0 9


0 . 5 6

0 . 5 4

2 5 . 1

1 2 . 0

2 4 . 9

9 . 9

0 . 5

1 7 9 . 5 4

1 2 5 . 4 6

4 0 0 . 3 3

M i n i m u m

1 . 1 0

1 . 2 0

6 2 . 0

6 . 0

− 4 9 . 0

0 . 0

4

2 0 0

1 3 9

3 0 9

M a x i m u m

3 . 0 0

3 . 0 0

1 3 7 . 0

4 6 . 5

− 4 . 0

2 5 . 0

5

7 3 6

5 1 6

1 6 4 7

C C c r a n i a l - c a u d a l a n g l e ,

F f e m a l e ,

M m a l e

Eur Radiol




randomised. In future a randomised study comparing the

robotic and non-robotic-assisted RFA needs to be carried out

with a larger sample size to determine the cost-effectiveness in

terms of time, cost and radiation dose to both patients and

operators. There is also a need for larger multi-centre studies

for cross-centre comparison.

Acknowledgments This study was supported in part by Perfint

Healthcare Pvt. Ltd,Florence, OR, USAwhich provided research funding

and equipment. The authors had no pertinent conflict of interest and had

unrestricted control of study data.

Open Access This article is distributed under the terms of the Creative

Commons Attribution Noncommercial License which permits any

noncommercial use, distribution, and reproduction in any medium,

provided the original author( s) and the source are credited.

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Eur Radiol




INTERVENTIONAL

Preliminary clinical experience with a dedicated

interventional robotic system for CT-guided biopsies of lunglesions: a comparison with the conventional manual technique

Michele Anzidei & Renato Argirò & Andrea Porfiri & Fabrizio Boni & Marco Anile &

Fulvio Zaccagna & Domenico Vitolo & Luca Saba & Alessandro Napoli & Andrea Leonardi &

Flavia Longo & Federico Venuta & Mario Bezzi & Carlo Catalano

Received: 22 May 2014 /Revised: 24 September 2014 /Accepted: 14 November 2014# European Society of Radiology 2014

AbstractObjective Evaluate the performance of a robotic system for

CT-guided lung biopsy in comparison to the conventional

manual technique.

Materials and methods One hundred patients referred for CT-

guided lung biopsy were randomly assigned to group A

(robot-assisted procedure) or group B (conventional proce-

dure). Size, distance from entry point and position in lung of

target lesions were evaluated to assess homogeneity differ-

ences between the two groups. Procedure duration, dose

length product (DLP), precision of needle positioning, diag-

nostic performance of the biopsy and rate of complications

were evaluated to assess the clinical performance of the robotic system as compared to the conventional technique.

Results All biopsies were successfully performed. The size

( p=0.41), distance from entry point ( p=0.86) and position in

lung ( p=0.32) of target lesions were similar in both groups( p=0.05). Procedure duration and radiation dose were signif-

icantly reduced in group A as compared to group B ( p=

0.001). Precision of needle positioning, diagnostic perfor-

mance of the biopsy and rate of complications were similar

in both groups ( p=0.05).

Conclusion Robot-assisted CT-guided lung biopsy can be

performed safely and with high diagnostic accuracy, reducing

procedure duration and radiation dose in comparison to the

conventional manual technique.

Key Points

• CT-guided biopsy is the main procedure to obtain diagnosis

in lung tumours.• The robotic device facilitates percutaneous needle place-

ment under CT guidance.

• Robot-assisted CT-guided lung biopsy reduces procedure

duration and radiation dose.

Keywords Robot . Lung biopsy . Lung cancer .

CT-guidance . Interventional radiology

Introduction

CT-guided lung biopsy is the procedure of choice to obtain

diagnoses in patients with pulmonary lesions suggestive of

malignancy at imaging [1 – 3]. Following the recent advances

in targeted therapies, biopsy of unresectable lung lesions has

also become necessary in order to assess genetic mutations in

unresectable non-small cell cancers (NSCLC), with core bi-

opsy usually being preferred to aspiration cytology owing to

the larger specimens made available for molecular analysis

[4]. CT-guided lung biopsy can be performed either with the

step-and-shoot or the fluoroscopic technique: the step-and-

M. Anzidei (*) : R. Argirò : A. Porfiri : F. Boni : F. Zaccagna :

A. Napoli : A. Leonardi : M. Bezzi : C. Catalano

Department of Radiological, Oncological and Anatomopathological

Sciences - Radiology – Sapienza, University of Rome, Viale Regina

Elena 324, 00161 Rome, Italy


M. Anile : F. Venuta

Department of Thoracic Surgery – Sapienza, University of Rome,

Rome, Italy

D. Vitolo


Sciences - Pathology – Sapienza, University of Rome, Rome, Italy

L. Saba

Department of Radiology, Azienda Ospedaliero Universitaria

(A.O.U.), di Cagliari-Polo di Monserrato, Monserrato, Italy

F. Longo


Sciences - Oncology – Sapienza, University of Rome, Rome, Italy

Eur Radiol

DOI 10.1007/s00330-014-3508-z





shoot approach is preferred in larger, non-moving lesions,

while CT-fluoroscopy is more advantageous when targeting

smaller lesions or nodules in the lower lobes that are suscep-

tible to respiratory motion [5]. Both procedures have technical

limitations that should be taken into consideration; in partic-

ular the step-and-shoot technique is based on the operator ’ssubjective assessment of needle path and positioning and may

result in increased procedure duration and complication rate,

whereas CT-fluoroscopy is significantly faster and more pre-

cise but significantly raises radiation dose to both operator and

patient [6, 7]. Various assisting technologies have been pro-

posed in order to increase the diagnostic accuracy and reduce

the duration of CT-guided biopsies, including external laser

targeting [8] and augmented reality (i.e. with a live indirect

view of anatomy by computer-generated video input) [9].

Dedicated interventional robotic systems that operate under

imaging guidance also became available recently [10].

However, while these systems may theoretically represent animportant step toward the automation of interventional proce-

dures, clinical experience and comparative data with conven-

tional techniques are still lacking or insufficient. The

ROBIO™ EX (Perfint Healthcare Pvt. Ltd, Florence, OR,

USA) is a CE approved robotic positioning system that facil-

itates percutaneous needle placement during CT-guided inter-

ventional procedures and that has been successfully tested for

CT-guided biopsy and ablation on phantoms [11] and for

clinical radiofrequency ablation of liver lesions [12]. The

objective of this study was to evaluate the clinical perfor-

mance of this system for CT-guided biopsy of lung lesions

in comparison with the conventional manual technique.


Patient population and study details

This was a single-centre, double-arm, non-sponsored, pro-

spective study and received the approval of local institution

review board. Between June 2013 and February 2014, 115

patients with previously diagnosed lung lesions suggestive of

malignancy at chest CT, PET-CT or both were referred to the

thoracic surgery department of our tertiary care hospital for

histological characterization. Fifteen patients were excluded

from the study population (three patients refused further diag-

nosis/treatment, in five patients the lesions were characterized

as lung metastases following review of available imaging and

in seven patients diagnosis was obtained with bronchoscopy

and transbronchial biopsy). The remaining 100 patients (63

male, 37 female, agerange 48 – 88 years,mean age 65±4 years)

were referred for CT-guided lung biopsy and randomly

assigned to group A (robot-assisted procedure) or group B

(conventional procedure). All enrolled patients gave their

written informed consent to participation after being

thoroughly informed of the benefits and potential risks of the

procedure.

Pre-procedure

All procedures were performed by the same radiologist (MA,8 years of experience in CT-guided interventions, including

more than 300 lung biopsies) on a 128-MDCT dual-source

scanner (Somatom Definition, Siemens, Erlangen, Germany).

A standard inspiratory breath-hold scan of the chest (100 kV,

100 mAs, detector configuration 128×1 mm, slice thickness

1 mm, reconstruction interval 1 mm) was acquired in all cases

prior to biopsy, in order to confirm the presence and to assess

the position of the target lesion. Patients were laid on a

vacuum stabilization mattress and positioned in order to re-

duce at minimum the intrapleural path of the needle, as well as

to avoid critical lung structures (vessels, bronchi and fissures).

Local anaesthesia was performed with 10 mL of 1 % lidocainealong the projected path of the biopsy needle into the soft

tissues, down to the epipleural space. In all cases an 18-G,

150/200-mm-long modified Menghini end-cutting needle

(SURECUT, TSK Laboratory, Tochigi-Shi, Japan) was used

for tissue sampling. Targeting CT scans were acquired with a

low-dose interventional protocol (100 kV, 50 mAs, detector

configuration 128×1 mm, slice thickness 1 mm, reconstruc-

tion interval 1 mm).

Conventional biopsy technique

All conventional biopsies were performed with the step-and-

shoot technique to assess needle positioning and angulation.

The z-axis extension of targeting scans was limited to include

only the needle and the target lesion. A minimum of two scans

(before the pleura and into the lesion) was required to target

lesions adjacent to the chest wall and a minimum of three

scans (before the pleura, midway to the lesion, into the lesion)

was required for deeper lesions. Additional scans and

multiplanar reconstructions were performed in real time when

necessary for needle adjustment. Once the needle tip was in

position, biopsy was performed with a combination of aspira-

tion and push/rotation movements.

Robot-assisted biopsy technique

Positioning and docking of the robotic system were performed

as previously described [11], with the arm and planning con-

sole located to the side of the CT bed (left or right, depending

on the required access) and firmly coupled to ground metal

plates on the floor to ensure stability. A preliminary inspira-

tory breath-hold CTof the chest was performed using a Breath

Hold® respiratory belt coupled to a light sign (Medspira,

Minneapolis, USA) mounted on a flexible arm, in order to

monitor the extent of chest movement and instruct patients to

Eur Radiol




maintain and reproduce proper apnoea (Fig. 1). Images were

then exported over a local area network to the ROBIO™ EX

workstation for biopsy planning. The centre of the target

lesion and the entry point on the skin were determined by

the operator, while the angulations of the needle, the depth of

the target and the needle path were automatically calculated bythe workstation and displayed in real time (Fig. 2). Each

parameter was readily modifiable by the operator in order to

avoid critical structures, such as ribs, bronchi and vessels.

Once the plan was confirmed, the CT table was moved to

the coordinates displayed on the workstation and the robotic

arm was activated and positioned for biopsy execution. A

plastic holder with a disposable bush was placed at the end

effector of the robotic arm to guide needle insertion.

Subsequently, the needle was manually inserted through the

chest wall directly into the lesion in a single pass, while the

patient maintained breath-hold to the same extent as that of the

initial positioning CT scan, guided by the light sign coupled to

the respiratory belt. After decoupling the needle from the end

effector and retraction of the robotic arm, needle positioning

was confirmed with a further CT scan (Figs. 3 and 4) and

adjustments were performed if required. Biopsy was then

performed similarly to the conventional approach.

Data analysis

The homogeneity assessment of the two groups included

evaluation of the size, distance from entry point and position

in lung of target lesions. The size and distance from entry

point were compared between the two groups with the unpaired sample t test. Differences in the location (according to

lobar anatomy) of target lesions between the two groups were

assessed with the Mann – Whitney U test.

In order to demonstrate statistically significant differences

( p<0.01) of clinical and technical performance between the

conventional biopsy approach and the robot-assisted tech-

nique, the following parameters were evaluated in the two

groups:

– Procedure duration (including planning time) and dose

length product (DLP) were compared with the unpaired

sample t test.

– Number of needle adjustments was compared with the

unpaired sample t test.

– Planar and craniocaudal deviations of the needle tip from

the planned target were calculated in millimetres and

compared between the two groups with the unpaired

sample t test. Multiplanar reformatted images were used

for the evaluation of z-axis deviation.

– Orbital and craniocaudal angular deviations at the target

from the projected needle path were calculated in degrees

(°) for robot-assisted biopsies only. Multiplanar

reformatted images were used for the evaluation of

craniocaudal angular deviation.

– Diagnostic performance of the biopsy procedure was

evaluated qualitatively (diagnostic/non-diagnostic sam-

pling) and compared with the Mann – Whitney test.

– The rate of complications in the two groups was evaluat-

ed following the clinical practice guidelines of the Society

of Interventional Radiology [13] (no complications/minor

complications/major complications) and compared with

the Mann – Whitney U test.

Results

All biopsies were successfully performed under CT guidance

in both groups. Lesions size ( p=0.41), distance from entry

point ( p=0.86) and lesions location ( p=0.32) were similar in

the two groups. Full results of the homogeneity assessment of

the two groups are given in Table 1.

In group A procedure duration was significantly shorter

( p=0.001), DLP was lower ( p=0.001) and just occasional

needle adjustments were required as compared to group B

( p=0.000). Planar and craniocaudal deviations of the needle

Fig. 1 Patient preparation. Respiratory belt placed in patients sight (a,

arrow) and coupled to the light sign (b, arrow). The belt registers the

extent of chest movement at each respiratory act and displays this as

coloured dots. More dots light up with wider respiratory movements. The

patients were asked to control their breath during the procedure trying to

avoid lighting of the outer dots

Eur Radiol




tip from the planned target were similar in both groups ( p=

0.05), while the orbital (transversal on the x-axis) and

craniocaudal (longitudinal on the z-axis) angular deviations

from the projected needle path in robot-assisted biopsies were

2±1° and 2.5±0.5° (Fig. 5). The diagnostic performance of

CT-guided biopsies was similar in the two groups ( p=0.05),

with four patients in group A and three patients in group B

Fig. 2 Biopsy planning on the ROBIO™ EX workstation. Target lesion

in the lower right lobe at contrast-enhanced CT (a, arrow), surrounded by

atelectasis (a, arrowhead ). The entry point on the skin (b, arrow) and

centre of target lesion (c, arrow) are determined by the operator. The

angulations and insertion path of the needle are automatically calculated

by the workstation and displayed in real time

Fig. 3 Needle positioning. Needle in position before insertion (a, arrow).

Needle insertion through the chest wall directly into the lesion in a single

pass (b, arrow). Needle in final position (c, arrow) after detachment from

end effector and retraction of the robotic arm

Eur Radiol




requiring re-biopsy due to inadequate quality of the biopsy

sample. The rate of complications was comparable in the two

groups ( p=0.05); there were three (6 %) cases of pneumotho-

rax in group A and two (4 %) cases of pneumothorax in group

B requiring chest tube drainage and prolonged hospitalization.

Minor complications (including small pneumothorax not re-

quiring therapy and self-limiting peri-lesional haemorrhages)occurred in two (4 %) cases in group A and four (7 %) in

group B. Full results of the assessment of the clinical and

technical performance of the two groups are given in Table 2.

Discussion

Imaging-guided interventional techniques currently represent

a fundamental tool in diagnosis and treatment of oncologic

pathologies. Among the various guidance modalities, CT is

the method of choice in the chest region owing to its excellent

spatial and contrast resolution for the visualization of lung parenchyma, airways and cardiovascular structures that safely

allows biopsy of lung and mediastinal lesions, percutaneous

tube placement and thermal ablation of lung tumours. The

conventional technique for CT-guided interventional proce-

dures requires a trial-and-error method with the step-and-

shoot approach, or the application of a real-time fluoroscopic

monitoring in order to visualize and modify the path of

needles and percutaneous probes. Even if the clinical perfor-

mance of conventional approaches is highly reliable in expert

hands [4 – 7], these methods present well-known technical

limitations and their successful application depends signifi-

cantly on operators’ manual skill and experience. In order to

reduce such operator dependence, several assisting devices

have been developed and tested in clinical practice, including

external laser [8] or optical [14] targeting systems that project

and/or guide the needle path onto the skin surface, electro-magnetic tracking with image fusion [15] and augmented

reality system under infrared guidance that display a real-

time simulation of needle movements [9]. Preliminary reports

are encouraging, but it should be noted that the success of

these technologies is highly dependent on the integration

between the assisting software/hardware, the CT system and

the operator, with increased complexity and costs as compared

to conventional techniques. Moreover, with the approaches

mentioned above the dependence on operator experience is

reduced but not completely eliminated, not mentioning the

need for adequate training. On the other hand, the use of

medical robots for surgical or imaging-guided proceduresallows extremely accurate tool guidance with stable access,

leading to increased precision, accuracy and reproducibility in

a variety of applications, including percutaneous ablations,

biopsies, orthopaedic fixture placement, hollow viscera or

solid organ access [10]. While earlier robots required exten-

sive installation and were often cumbersome to operate, being

time consuming and economically disadvantageous [16, 17],

more recent systems, such as the ROBIO™ EX, require

minimal effort to be mounted and registered to the imaging

Fig. 4 Positioning confirmation after control scan, immediately before

biopsy. Adjacent slices demonstrate overlapping between the planned

needle path ( green line) and the actual needle position at the end of

insertion. Robot-assisted biopsy allowed correct sampling of tumour

tissue avoiding atelectasis. Final histological diagnosis was

adenocarcinoma

Table 1 Full results of the homogeneity assessment of the two groups

Parameter Group A Group B p value

Lesion size (mm) 40.7±23.9 (range 15 – 150) 35.5 ±25 (range 13.5 – 160) 0.41

Distance from Entry point (mm) 73.1 ±30.7 (range 20 – 135) 72.1 ±21.6 (range 18 – 117) 0.86

Lesion location (according to lobar anatomy) RUL (n 11) RUL (n 9) 0.32

LUL (n 6) LUL (n 8)

ML (n 3) ML (n 2)

RLL (18) RLL (16)

LLL (12) LLL (15)

Values are expressed as average±standard deviation

RUL right upper lobe, LUL left upper lobe, ML middle lobe, RLL right lower lobe, LLL left lower lobe

Eur Radiol




device [11], reducing the complexity of the procedure. Also

the fully automated movement of the robotic arm represents a

relevant advantage that removes the need for manual or joy-

stick adjustments in the pretreatment phase that are necessary

with other devices [18, 19] and may further complicate the

clinical workflow. From a clinical point of view, our studydemonstrated in a large patient population that the presented

robotic system facilitates CT-guided lung biopsies, with re-

sults that are substantially in line with previous reports on

biopsies in phantoms [11] and clinical radiofrequency ablation

of liver lesions [12]. It should be considered that, apart from

these two preliminary studies performed with the same robotic

platform, there is no literature evidence of large clinical series

of robot-assisted CT-guided interventions, in particular for

what regards chest procedures; hence, an indirect comparison

with the performance of different robotic devices is currently

impossible. In our single-centre experience, the precision in

lesion targeting, the diagnostic performance of the biopsy

sampling and the rate of complications in the robot-assisted

procedures were comparable to those of conventional biop-

sies, with accurate needle positioning and very few adjustment

required even in lesions as small as 15 mm, but the use of the

robot significantly reduced procedure duration and radiation

dose in comparison to the unassisted technique. This observa-

tion is particularly relevant, since in our study all procedures

were performed by an operator with previous experience of

more than 300 conventional CT-guided lung biopsies and,

notwithstanding this expertise, significant reduction of proce-

dure duration and radiation dose were in any case obtained in

robot-assisted procedures as compared to the conventional

technique. In this regard, future work should aim to evaluate

when and how operators with different levels of experience

may benefit from robot assistance in daily clinical routine, and

assess potential differences in the clinical performance of

robot-assisted procedures between expert and non-expert

Fig. 5 Biopsy of a deep solitary lung nodule in the right upper lobe. The

maximum transverse diameter of the nodule was 10 mm and its

craniocaudal size was 15 mm. Planning CT demonstrates the desiredneedle path and tip positioning (a, arrowhead ). Control CT scan after

needle positioning shows a slight angular deviation of the needle tip

resulting in a 1.5-mm deviation from the planned path ( b, arrowhead ).

Notwithstanding the deviation, biopsy was successfully performed

without further needle adjustments, achieving final histological

diagnosis of adenocarcinoma

Table 2 Full results of the assessment of the clinical and technical performance of the two groups

Parameter Group A Group B p value

Procedure duration (min) 20.1 ± 11.3 (range 10 – 31) 31.4±10.2 (range 18 – 42) 0.001

DLP (mGy) 324±114.5 (range 117 – 386) 541.2±446.8 (range 334 – 589) 0.001

Number of needle adjustments 2.7± 2.6 (range 1 – 4) 6±4 (range 2 – 12) 0.000

Deviations on the x and y axes (mm) 2.3 ± 1.1 ( x) 2.5±1.5 ( y) (range 1 – 8) 3.0±1.3 ( x) 2.1±1.6 ( y) (range 2 – 11) 0.05

Orbital (o) and craniocaudal (c)

deviations (°)

2±1° (o) 1.5±0.5° (c) N/A N/A

Final diagnosis 18 ADCA, 9 SCC, 6 SCLC, 10 mets,

3 benignant

15 ADCA, 10 SCC, 7 SCLC, 14 mets,

1 benignant

0.05

4 rebiopsy (1 ADCA, 2 SCC, 1 SCLC) 3 rebiopsy (2 ADCA, 1 SCC)

Complications (%) 10.4 11 0.05

Values are expressed as average±standard deviation

ADCA adenocarcinoma, SCC squamous cell carcinoma, SCLC small cell carcinoma, mets metastases, N/A not acquired

Eur Radiol




radiologists. Moreover, even if a dedicated cost-analysis is

currently unavailable, it could be speculated that the use of

interventional robotic systems will be probably even more

beneficial in clinical settings in which financial resources or

time for appropriate training of interventional radiologists is

lacking, pushing less expert, non-interventional operators to perform simple imaging-guided procedures. Even if these

preliminary results are encouraging, this study has some lim-

itations. First, the sample size was not determined in advance

with a power analysis in order to increase the relevance of the

statistical evaluation. Moreover, a statistical subanalysis based

on the anatomic characteristics of the target lesions (size,

distance to pleura and position in lung) was not performed;

hence we cannot provide clustered data on system perfor-

mance for the biopsy of smaller and hardly accessible lesions,

which should be the ideal target for robot-assisted procedures.

Last, an independent evaluation of the status of the lung

parenchyma surrounding the target lesions was not available

in order to assess the influence of local pulmonary factors

(emphysema, fibrosis, bronchiectases) on the rate of compli-

cations in the two groups, even if this parameter was probably

not influential, since our complication rates do not differ from

those reported in the literature [4 – 7]. Notwithstanding these

limitations, the results of our study demonstrate that robot-

assisted CT-guided lung biopsy is a safe and accurate inter-

ventional technique that can reduce procedure duration and

radiation dose in comparison to the conventional manual

approach even in expert hands. Further studies are needed to

confirm these data and to evaluate the performance of robot-

assisted interventional procedures in other clinical scenarios.

Acknowledgments The scientific guarantor of this publication is Dr.

Michele Anzidei. The authors of this manuscript declare no relationships

with any companies whose products or services may be related to the

subject matter of the article. The authors state that this work has not

received any funding. Dr. Fulvio Zaccagna kindly provided statistical

advice for this manuscript. Institutional review board approval was ob-

tained. Written informed consent was obtained from all subjects (patients)

in this study. No study subjects or cohorts have been previously reported.

Methodology: prospective, randomised controlled trial, performed at one

institution.

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Eur Radiol




INTERVENTIONAL

Accuracy and efficacy of percutaneous biopsy and ablation

using robotic assistance under computed tomographyguidance: a phantom study

Yilun Koethe & Sheng Xu & Gnanasekar Velusamy &

Bradford J. Wood & Aradhana M. Venkatesan

Received: 25 July 2013 /Revised: 24 September 2013 /Accepted: 10 October 2013# European Society of Radiology (outside the USA) 2013

Abstract

Objective To compare the accuracy of a robotic interventional

radiologist (IR) assistance platform with a standard freehand

technique for computed-tomography (CT)-guided biopsy and

simulated radiofrequency ablation (RFA).

Met hod s The accuracy of freehand single-pass needle

insertions into abdominal phantoms was compared with

insertions facilitated with the use of a robotic assistance

platform (n =20 each). Post-procedural CTs were analysed

for needle placement error. Percutaneous RFA was simulated

by sequentially placing five 17-gauge needle introducers into

5-cm diameter masses (n =5) embedded within an abdominal

phantom. Simulated ablations were planned based on pre-

procedural CT, before multi-probe placement was executed

freehand. Multi-probe placement was then performed on the

same 5-cm mass using the ablation planning software and

robotic assistance. Post-procedural CTs were analysed to

determine the percentage of untreated residual target.

Results Mean needle tip-to-target errors were reduced with

use of the IR assistance platform (both P <0.0001). Reduced

percentage residual tumour was observed with treatment

planning ( P =0.02).

Conclusion Improved needle accuracy and optimised probe

geometry are observed during simulated CT-guided biopsy

and percutaneous ablation with use of a robotic IR assistance

platform. This technology may be useful for clinical CT-

guided biopsy and RFA, when accuracy may have an impact

on outcome.

Key points:

• A recently developed robotic intervention radiology

assistance platform facilitates CT-guided interventions.

• Improved accuracy of complex needle insertions is

achievable.

• IR assistance platform use can improve target ablation

coverage.

Keywords Interventional radiology . Robotics .

Image-guided biopsy . Ablation techniques

Abbreviations

IR Interventional radiologist

RFA Radiofrequency ablation

Y. Koethe : S. Xu : B. J. Wood : A. M. Venkatesan

Center for Interventional Oncology, NIH Clinical Center, National

Institutes of Health, Bethesda, MD, USA

Y. Koethe : B. J. Wood : A. M. Venkatesan

Radiology and Imaging Sciences, NIH Clinical Center, National

Institutes of Health, Bethesda, MD, USA

Y. Koethe

Duke University School of Medicine, Durham, NC, USA

G. Velusamy

Perfint Healthcare Pvt. Ltd., Chennai, India

A. M. Venkatesan (*)

Center for Interventional Oncology, Radiology and Imaging

Sciences, NIH Clinical Center, National Institutes of Health, 10

Center Drive, Building 10 CRC, Room 1C369, MSC 1182,

Bethesda, MD 20892, USA


Eur Radiol

DOI 10.1007/s00330-013-3056-y





Introduction

P e rc u ta n e o u s c o mp u te d -to mo g ra p h y (CT )-g u id e d

interventions can be used effectively for image-guided biopsy

and tumour ablation [1]. CT-guided biopsy can effectively

obtain samples for histological assessment of a tumour, and

is advantageous given its minimally invasive approach and

ability to enable visualisation of deep tissues [2]. However, the

accuracy of CT-guided needle placement, which influences

diagnostic yield, is highly dependent upon physician

experience. Vulnerable anatomy (such as bowel, nerves

or vessels in proximity to the target) has low tolerance for

needle placement errors. With conventional techniques,

challenging biopsy targets frequently mandate multiple needle

adjustments and intra-procedural imaging, which can prolong

procedure duration, and increase patient radiation exposure

and procedural risk [3, 4]. Needle-based thermal ablation such

as radiofrequency ablation (RFA) induces coagulative

necrosis of tumours such as hepatocellular carcinoma, hepatic

metastases and renal cell carcinoma [1, 3, 5 – 8]. While RFA

has been shown to achieve results comparable to surgical

resection for small tumours, such as hepatocellular

carcinomas <3 cm, its efficacy has been shown to be reduced

for larger tumours [6, 9, 10]. In addition to greater heat sink

effect with larger, more perfused tumours, reduced efficacy of

RFA for large tumours may be in part attributable to multi-

probe placement complexity, which is prone to human error.

This is critical for successful large volume composite ablation,

however, in order to achieve ablation of both tumour and an

intended tumour-free margin [11, 12].

Navigational software and robotic assistance may offer a

tailored solution to physicians confronting a technically

challenging biopsy or ablation target. Early phantom and

clinical experience with robotic navigation systems suggest

procedural accuracy, reduced procedure time and reduced

patient radiation exposure compared with freehand techniques

[13 – 19]. Experience with software systems enabling ablation

planning has also been favourably described [20, 21]. In this

study, an IR assistance platform was evaluated that combines

navigational software and robotic guidance to facilitate

percutaneous biopsy and ablation probe placement. Needle

placement accuracy and ablation efficacy were assessed in

abdominal phantoms.


Robotic IR assistance platform device

Device specifications, emergency options

The robotic IR assistance platform (MAXIO; Perfint

Healthcare, Chennai, India) has dimensions of 850 mm×

800 mm×1,350 mm (length × width × height) in the parked

position) and 850 mm× 800 mm ×1,800 mm when docked at

the CT table side, with the robotic arm positioned over the CT

table. The weight of the device is 250 kg and it is propelled via

four way swivel wheels. The device requires between

approximately 3-4 min total to be physically moved from its

parked position to CT tableside, to dock the device and boot it

up. It requires approximately the same amount of time to

switch off the device, undock and move it to the parking

location identified inside the CT suite. The device’s robotic

arm takes approximately 30-45 s to move from its initial

position to the position to clamp the needle guide.

Two emergency shut off functions are available for this

device. One is an emergency switch physically located on the

robotic arm, whose actuation will stop all device axis

movement. If the needle guide is already clamped the device

will release the clamped needle holder immediately and the

device will be restored to a “safe state”, during which all the

movement related components of the device are stopped and

no further movement is possible before intervention by the

user to reset the position values and command the device to

move again. The device also has a Cancel Movement option

in the software which the user may click on using the device’s

track pad. This will also stop all movements and restore the

device to its “safe state”.

Physical docking, optical registration and DICOM data

retrieval

Registration between the robotic IR assistance platform and

the CT table occurs via a mechanical docking mechanism,

optical registration and tilt sensing (MAXIO; Perfint,

Chennai, India) (Fig. 1a ). Provided all three components of

registration (mechanical docking, optical registration and tilt

sensing) are successfully executed, the platform permits

pro cedures to be car ried out. Con sistent doc kin g and

registration of the robotic device abrogates the need for

robot-to-CT registration with each use. The platform’s

computer console receives DICOM formatted images from

the CT console via an Ethernet cable, and displays the images

on its planning and navigation software.

Biopsy and ablation planning software

The system has a track pad for the user to interact with the

computer. Using the track pad, the physician selects the needle

or probe type and length from a series of drop-down menus on

the computer console integrated into this device. Needle/probe

trajectory and biopsy or ablation target are selected directly on

the DICOM data transferred to the device’s computer console.

DICOM CT data may be displayed in the axial as well as

sagittal and coronal planes by the graphical user interface. The

physician operator plans a biopsy with the navigational

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software by selecting the intended probe type and length, then

selecting the target and skin entry site directly on the DICOM

imaging data (Fig. 2). After these inputs, the system software

subsequently instructs the operator to move the CT table to a

prescribed z -axis location. It then prescribes the trajectory to

the robotic arm. For ablation planning, the physician segments

the target by using the track pad to hover the computer cursor

over the target on pre-procedural CT. Based on differences in

voxel intensity, the software generates a preliminary

segmentation on multi-planar reformatting images and a

three-dimensional (3D) reconstruction. If necessary, the

physician manually edits the segmentation until satisfactory.

The physician can subsequently plan the ablation by dictating

the probe type and trajectory. The platform displays a

simulated composite ablation zone over the axial,

reconstructed coronal and reconstructed sagittal images, and

co-displays the target and superimposed ablation geometry on

the 3D reconstructions (Fig. 3). As the operator adds

additional probes to the composite ablation plan, the ablation

planning software updates the displayed ablation zone to

reflect additional probe contributions to the total ablation

volume.

Robotic assistance for biopsy/ablation

The computer console communicates with the robotic guide

arm via an RS232 interface to move according to the

physician dictated plan. The robotic guide arm possesses 5

degrees of freedom and is able to achieve needle insertions up

to 230 mm from the gantry centre line to the side opposite that

of the docked device. Those needle angles or skin entry sites

outside of this range mandate installation of another floor

mounted docking plate on the other side of the examination

table and physical docking of the robotic on the contralateral

table side. Once the robotic arm has moved to the correct

location, the physician operator instructs the end effector of

the robotic guide arm via the computer console to grip a plastic, gauge-specific needle guide (Fig. 1b). The physician

then manually inserts the needle through the needle guide until

the needle hub contacts the needle guide. Once the needle is in

place, the physician instructs the robotic device to unclamp its

end effector and withdraw its robotic arm from the procedural

site.

Experimental set-up

The IR assistance platform was physically docked on the right

side of the CT table (Philips Brilliance iCT; Philips

Fig. 1 Robotic interventional

radiologist (IR) assistance

platform set-up. a The robotic

arm at baseline position (black

arrowhead ). Foot pedals (white

star ) can be used to initiate

robotic arm movement andopening and closing of the end

effector. Planning of percutaneous

interventions are carried out and

displayed on the monitor of the

platform’s computer console). b

Robotic arm end effector grips

onto the inserted needle guide

before needle insertion

Fig. 2 Single-pass needle insertion planning using an IR assistance

platform. Point target is delineated (white arrowhead ) on axial images

as well as reconstructed coronal and sagittal images (not pictured).

Simulated needle trajectory is displayed as a dotted line on anatomical

images

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Healthcare, Cleveland, OH, USA) (Fig. 1). Image acquisition

properties were based on the manufacturer ’s recommendations

(5-mm section thickness, 1-mm reconstruction interval).

Optically opaque abdominal phantoms (Triple Modality 3D

Abdominal Phantom Model 057; CIRS, Norfolk, VA, USA)

were used for needle and probe placement. All needle

insertions were performed by an attending interventional

radiologist with 7 years of percutaneous biopsy and ablation

experience.

Needle placement for biopsy

Twenty pairs of virtual point targets and skin entry points with

a mean entry-to-target distance of 11.0 cm (range, 10.2 –

11.5 cm) were selected on pre-procedural CT using custom

software (intGuide; National Institutes of Health, Bethesda,

MD, USA). Each pair of target and skin entry points

comprised a complex multi-angle needle trajectory with

angular deviations in the x , y and z directions. Single-pass

needle insertions were performed using an 18-gauge, 15-cm

needle (Biomedical SRL, Firenze, Italy). Insertions were first

performed using a freehand technique, employing only the CTgantry laser light and the markings of the CT grid placed over

the phantom during pre-procedural imaging and for

localisation (Fast Find Grid; Webb Manufacturing

Corporation, Philadelphia, PA, USA). Insertions were

subsequently performed with the use of the IR assistance

platform. Neither intra-procedural needle adjustments nor

intra-procedural CTs were permitted for either approach.

Needle placement for composite ablation simulation

Custom opaque abdominal phantoms (CIRS, Norfolk, VA,

USA) were designed containing multiple 5-cm diameter

embedded masses meant to simulate 3-cm diameter tumours

and surrounding 1-cm tumour-free margins. For each target,

five simultaneous RFA electrode placements were planned

with the intent of maximising simulated ablation of the target

(i.e. simulated tumour and tumour-free margin). A total of five

17-gauge, 15-cm needle introducers (Cardinal Health, Dublin,

OH, USA), simulating 15-cm long, 3-cm active tip CoolTip

RFA Electrodes (Covidien, Dublin, Ireland), were inserted

into the 5-cm diameter embedded targets. Ablations were first

planned manually on the CT console after obtaining an initial

CT of the phantom. Needle insertions were then executed

freehand, employing only the CT gantry laser light and the

markings of the CT grid placed over the phantom during pre-

procedural imaging for localisation. Probe placement was

subsequently planned and executed using the IR assistance

pla tform’s ablation planning software. Neither needle

adjustments nor intra-procedural CTs were permitted between

needle insertions. Post-procedural imaging documenting

needle locations and positions was obtained subsequent to

needle placement for each technique.

Image analysis

Custom software (intGuide; National Institutes of Health,

Bethesda, MD USA) was used to select the needle tip on the

post-procedural CTs obtained after biopsy needle insertion.

The custom software subsequently calculated the Euclidian

distance between the tip of the needle and the virtual target,

corresponding to the “tip-to-target distance.”

Custom research software (OncoNav; National Institutes of

Health, Bethesda, MD, USA) derived from Medical Image

Processing, Analysis and Visualization (MIPAV) software

(National Institutes of Health) was employed for simulated

ablation analysis [22]. The target was manually segmented,

and each needle displayed on post-procedural CT was

Fig. 3 Ablation planning on an IR assistance platform. Ablation

planning software displays axial images (a) as well as reconstructedcoronal and sagittal images (not pictured). After tumour segmentation

(segmented tumour: white arrow, a ), probes are planned and their

trajectories displayed on the anatomical images (probes: solid/dotted

lines in a ). The predicted composite ablation zone is superimposed onto

the segmented tumour on both multiplanar images and on a 3D shaded

surface display (composite ablation zone: black arrow in a , white

arrowheads in b )

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manually outlined. Ablation zone geometry and size was

subsequently predicted based on needle placement and

manufacturer-prescribed ablation size (3.6× 3.7 cm ellipsoidal

coverage per needle) [23]. The software subtracted the

composite ablation volume from the segmented target volume

thereby calculating the percentage residual non-ablated target (Fig. 4).

Statistics

Paired t- tests were used to compare the differences in needle

tip-to-target distance for simulated biopsy. Paired t -tests were

also used to compare the differences in percentage residual

target for simulated ablation. 95 % confidence intervals were

assumed (α ≤0.05). Descriptive statistics were employed to

calculate mean entry-to-target distance and mean angular

deviation for simulated biopsy.

Results

Mean entry-to-target distance was 11.0±3.8 cm (range, 10.2 –

11.5 cm) for needle insertions simulating percutaneous biopsy.

A shorter mean needle tip-to-target distance was observed

with use of the IR assistance platform compared with the

freehand technique (6.5±2.5 mm vs 15.8±9.2 mm,

respectively; P <0.0001; Fig. 5a ). Mean absolute angular

deviation off the z -axis was 53° (range -68° to 74°). Mean

absolute angular deviation off the y -axis was 46° (range -42°

to 56°).

For simulated composite ablation, a lower average

percentage of residual target was observed with use of the

IR assistance platform (13.0±4.0 %) compared with the

freehand technique (25.1±10.9 %; P =0.03; Fig. 5b).

Discussion

In this study, we evaluated the accuracy and efficacy of an

integrated IR assistance platform for multi-angle needle

placements and ablation planning. Improved needle accuracy

compared with freehand technique was demonstrated with the

use of this IR assistance platform for challenging, single-pass,

multi-angle needle trajectories.

F i g. 4 Analysis of ablation coverage. Representative image

demonstrates residual target volume (black asterisks ) and ablated

volumes (white ovals) around inserted needles (white arrows)

Fig. 5 Scatter plots demonstrate the distribution of tip-to-target distance

(a) for freehand and IR assistance platform-guided needle insertion. b

Before-after plots demonstrate percentage residual tumour for each target

using the freehand technique and the IR assistance platform

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Improved needle placement accuracy may clinically

translate into decreased complication rates and greater

sampling success for biopsies [6, 9, 10, 24]. Out-of-plane

trajectories have traditionally been challenging to plan with

CT guidance. If the entry point and the target are in two

different planes, only one can be visualised at a time, makingit challenging to plan multi-angle trajectories. Compared with

traditional CT guidance, cone beam CT or fluoroscopically

guided interventions offer an advantage of enabling

orthogonal and oblique projections of the skin entry site and

target [11, 17]. With this novel IR assistance platform, the

challenges of multi-angle visual planning are further

circumvented. The skin entry and the target points can be

directly planned on the computer console of the IR assistance

platform, which subsequently executes the planned trajectory,

without requiring physician calculations of entry-to-target

distance and angulation.

Reduced variability of needle placement accuracy was also

noted with IR assistance platform guidance compared with the

freehand technique. A potential explanation for this

observation is that freehand needle accuracy is dependent

upon physician comfort and skill with a particular angulation

and insertion depth, whereas the IR assistance platform does

not face this limitation, being presumably equally accurate for

both simple and complex angles. Although not evaluated in

this study, a novice with limited experience in executing

complex multi-angle trajectories might be able to acquire

visual, and some tactile experience, by first executing the

trajectory with use of this IR assistance platform. The

platform’s role as a training tool remains an interesting area

for further investigation. While treatment planning is

frequently used in image-guided external beam radiation

therapy and brachytherapy, ablation zone simulation and

planning for interventional oncology remains relatively novel

[25]. In this study, the use of the ablation planning component

of this IR assistance platform was associated with greater

target coverage and reduced residual target compared with

the freehand technique.

One limitation of the ablation planning component of this

platform that should be noted is that the simulated ablation

volumes are manufacturer-predicted isotherms, derived

largely from ex vivo data. The actual ablation volume may

vary depending on tissue type, energy source, electrode, and

local microscopic and regional perfusion factors [26].

Navigati on and guidance tools have the pote ntia l to

mitigate imperfect operator spatial awareness and hand-eye

coordination. Non-robotic navigation and guidance devices

that assist physicians include electromagnetic (EM) tracking,

optical tracking, laser guidance and cone beam CT fusion.

Optical and EM tracking provide information on real-time

needle position and orientation, but mandate the use of costly

disposables such as EM or optically tracked needles [27, 28].

In addition, they may require extensive pre-procedural

registration, which can be consuming as the location of

fiducial markers and EM field generators (or cameras for

optical tracking) must be accommodated intra-procedurally

[13 – 17, 29]. Laser guidance has no physical needle guide to

steady the needle during insertion. Cone beam CT fusion

requires installation of a C-arm and other hardware that mayoccupy an entire IR suite.

The IR assistance platform used in this study, in

comparison, requires minimal time for docking and

registration. Like other robotic devices, it can also accurately

orientate and guide multi-angle needle insertions without

necessitating the use of custom needles. Schulz et al. [17].

have recently described a robotic device that assists

per cutan eou s nee dle inser tion for con e bea m CT and

f l u or o s c op y - g ui d e d p r o c ed u r e s ( i S Y S 1 ; i S Y S

Medizintechnik, Kitzbuehel, Austria). This device is mounted

to a small platform beneath the CT table, and has 4 degrees of

fre e d o m. A p h a n to m s tu d y e mp lo y in g th is d e v ic e

demonstrated that accurate needle placement can be achieved

in a timely manner (average error, 1.1 mm; average duration

of procedure, 3:59 min). Solomon et al. [13] and Patriciu et al.

[14] have also recently described a robotic system with a total

of 11 degrees of freedom that is mounted on a large frame

attached to and overlying the CT table (PAKY-RCM; Johns

Hopkins, Baltimore, MD, USA). This device has a rolling

dowel mechanism that can advance a needle without

physician assistance. Use of this device for percutaneous

interventions demonstrated accuracy (average error,

1.7 mm), reduced overall procedure time, number of probe

passes, and patient an d phy sician radiatio n exposure

compared with conventional techniques.

Compared with other robotic devices for image-guided

interventions, this IR assistance platform also has a large range

of achievable needle angles, ranging from -90° to 90° in both

lateral and craniocaudal directions, provided installation of

floor mounted plates and docking on either site of the

examination table has been enabled. The automated aspect

of this system’s robotic arm offers additional unique

advantages. Whereas the robotic guide arm of other existing

devices must be manually positioned in the vicinity of the

target before subsequent end effector localisation is achieved

automatically or via joystick use, the robotic guide arm of this

platform automatically moves from its docked position to the

skin entry point based on the physician dictated plan [17, 20,

21, 30]. As this platform abrogates the need for manual

movement of the device after initial registration and docking,

the physician can focus on the biopsy and ablation planning

steps instead of manually moving the robot during the

procedure. Additional advantages of this platform include its

mobility, as it can be wheeled away from the CT when not in

use.

The limitations of this robotic platform are similar to those

of other robotic guidance devices. Once docked, this platform

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limits physical access on one side of the CT table near the

gantry. In addition, physical docking of the device limits the

overall range of craniocaudal targets that are accessible.

Another limitation is the fact that tactile experience

diminished when using this device, as the needle holder

clamps tightly around the needle. Furthermore, as we onlyreport a phantom study, we were not able to evaluate this

technique in the in vivo environment, when specific

challenges like target, patient and respiratory motion must be

surmounted. But in this initial study phantom study, we were

interested to evaluate the ability of this system to facilitate

complex needle angle insertions compared with an

experienced operator ’s freehand single pass insertion. It

should also be noted that a single pass needle insertion is not

the standard procedure for complex clinical needle

placements. It would be of interest to pursue a follow-up study

wherein the operator was permitted multiple needle angle

adjustments with a series of CT check images to reach a point

target, thereby allowing us to compare both needle tip-to-

target accuracy as well as radiation dose for freehand versus

robotically assisted techniques.

It is arguably difficult to compare the results of this study

with those of existing studies describing robotic device use for

percutaneous interventional procedures, as each published

study has evaluated different endpoints in different ways.

Some devices have demonstrated smaller tip-to-target distance

compared with the IR assistance platform employed in this

study. However, this could be explained by differences in

experimental design or the phantom used. Our experimental

design called for challenging multi-angle trajectories.

Descriptive analysis revealed that all trajectories chosen had

challenging angulations with a minimum of 33° of absolute

deviation both from z -axis and from the midline, and a

minimum needle depth of 10 cm. Studies employing other

robotic devices have described use of smaller needle angles,

which may be in part due to the smaller range of angles

achievable with these devices [17].

In conclusion, results from the use of this novel IR

assistance platform suggest that it might play a promising role

for percutaneous CT-guided biopsies and ablations. Its use

was associated with improved needle placement accuracy

for complex, multi-angle trajectories and greater ablation

coverage for large targets compared with the freehand

technique. Future studies are needed to evaluate the role of

this IR assistance platform in the clinical setting and to

determine its effect on radiation exposure, patient risk and

clinical outcome.

Acknowledgements A year-long research fellowship for Y.K. was

made possible through the National Institutes of Health (NIH) Medical

Research Scholars Program, a public-private partnership supported

jointly by the NIH and generous contributions to the Foundation for the

NIH from Pfizer Inc., The Leona M. and Harry B. Helmsley Charitable

Trust, and the Howard Hughes Medical Institute, as well as other private

donors. For a complete list, please visit the Foundation website at http://

www.fnih.org/work/programs-development/medical-research-scholars-

program). The content of this publication does not necessarily reflect the

views or policies of the Department of Health and Human Services, nor

does mention of trade names, commercial products, or organizations

imply endorsement by the U.S. Government.

X.S.: No potential conflicts of interest to disclose.G.V. is a full-time salaried employee (Principle Systems Architect,

ATO) of Perfint Healthcare Pvt. Ltd. Perfint Healthcare owns intellectual

property related to technologies used in this published work, including

USPTO # US20130072784, US20120190970, US20130085380, etc. For

d e t a i l e d i n f o r m a t i o n , p l e a s e v i s i t t h e c o m p a n y w e b s i t e ,

www.perfinthealthcare.com.

B.J.W. and A.M.V: This research was supported by the NIH

Intramural Research Program and the NIH Center for Interventional

Oncology. The interventional radiologist assistance platform was

supplied by Perfint Healthcare Pvt. Ltd. (Chennai, India) under a

Materials Transfer Agreement between the NIH Center for Interventional

Oncology and Perfint Healthcare. NIH and Perfint Healthcare have

discussed details of a draft Cooperative Research and Development

Agreement (CRADA). The content does not necessarily reflect the views

or policies of the Department of Health and Human Services, nor doesmention of trade names, commercial products or organisations imply

endorsement by the U.S. Government.

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Robot-assisted navigation system for CT-guidedpercutaneous lung tumour procedures: our initialexperience in Hong KongCM Chu*, SCH Yu

From International Cancer Imaging Society (ICIS) 14th Annual Teaching Course

Heidelberg, Germany. 9-11 October 2014

Purpose

To evaluate the new robot-assisted navigation system for

CT-guided lung tumour procedures


Imaging-guided lung procedures are usually challenging

due to patient breathing. This is an ongoing prospective

study with 50 patients targeted in a university-based hospi-

tal. This was an initial assessment of efficacy involving

10 patients with lung tumours who underwent CT-guided

lung interventions utilizing the robot-assisted Navigation

system (Maxio, Perfint Healthcare, USA). The targeted

needle pathway was planned on Maxio Robotic system

based on pre-procedural CT-scans. The primary endpoint

was satisfactory instrument position for intended inter-

ven tio n. Les ion siz e and dep th fro m skin wer e noted.

Performance level was documented on a five-point scale

(5-1: excellent-poor). Total radiation doses were recorded

and compared against 20 patients with conventional CT-

guidance and CT-fluoroscopy lung procedures (ratio 1:1).

Results

There were 7 male and 3 female patients in the robotic

group. Average age was 72.1 years (range 67-78).

8 patients underwent lung biopsy while the rest hadthermal ablation or fiducial marker insertion. Average

lesion size was 2.8cm (range 1.9-4.1cm). Average lesion

depth was 6.2cm (range 3.7-8.6cm). All interventions

met the primary endpoint of satisfactory instrument

positioning. Average performance levels were 4.5. Aver-

age radiation dose (Dose Linear Product) was 480.4

(range 196.5-959.8) whereas conventional CT-guidance

was 645.4 (range 285.1-1043.5) and CT-fluoroscopy was

460.1 (range 214.2-1157.0).

Conclusions

Our initial experience demonstrated effectiveness of the

robot-assisted navigation system for CT-guided lung

tumour interventions with lower radiation dose compared

with conventional CT-guided procedures. Radiation doses

were similar to CT-fluoroscopy without radiation expo-

sure to interventional radiologists. Targeting success rate

for satisfactory intervention was 100%.

Published: 9 October 2014

doi:10.1186/1470-7330-14-S1-S5Cite this article as: Chu and Yu: Robot-assisted navigation system for

CT-guided percutaneous lung tumour procedures: our initial experiencein Hong Kong. Cancer Imaging 2014 14 (Suppl 1):S5.

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* Correspondence: [email protected] of Imaging and Interventional Radiology The Chinese University

of Hong Kong, Prince of Wales Hospital, Shatin, N.T., Hong Kong

© 2014 Chu and Yu; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons

Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproductionin any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver(http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.





Technical note: CT-guided biopsy oflung masses using an automated guiding

apparatusAmarnath Chellathurai, Saneej Kanhirat, Kabilan Chokkappan, Thiruchendur S Swaminathan,

Nadhamuni KulasekaranBarnard Institute of Radiology, Madras Medical College, Government General Hospital, Chennai- 600 003, India

Correspondence: Dr Amarnath Chellathurai, 52, Khanabagh Street, Triplicane, Chennai- 600 005, India. E-mail: [email protected]

Introduction

CT-guided lung biopsy is a usually done manually, using

a standard technique. For some years now, automated

systems have been available to guide biopsies.[1,2] We discuss

our experience with a newly developed indigenous system.

Technique

We used PIGA-CT (a robotic five-axes guide arm and

planning console) designed by Perfint Healthcare Pvt.

Ltd. (Chennai, India); it is an automated apparatus that

calculates coordinates on DICOM images from a CT scanner

and guides the placement of a needle accurately within the

body aer insertion [Figure 1].

The apparatus consists of an electromechanical guide arm

that provides ve degrees of freedom, a computer console

for receiving CT images and calculating coordinates, and an

RS232 interface for data communication between the guide

arm and the computer console. Precise ‘point of insertion’

and ‘point of target’ are determined from the images and

marked. The apparatus is able to accurately position itself

by using the movement in ve axes. The manipulator aligns

the needle guide. The needle is required to enter the body at

the ‘point of insertion’ and to touch the target at the ‘point

of target’ [Figures 2 and 3].

Of 36 consecutive CT-guided needle biopsies of the chest

performed at our institute between 30th June 2007 and

24th January 2008, 18 (group I) were performed using

manual planning and 18 (group II) with the automated

biopsy system. A four-slice CT scanner (Toshiba; DICOM

compatible) was used to localize the lesion and to guide

needle placement. No cytopathologists were present at the

time of biopsy.

Seven (19%) small post-biopsy pneumothoraces complicated

the 36 procedures; none of them required placement of a

chest tube. Four cases occurred while using the manual

method and three during the automated method. In

this study, the technical success was 100% with both themethods. Using the manual method, 11 biopsies (61.1%)

yielded sucient tissue for pathologic evaluation whereas,

with the automated apparatus, 12 (66.7%) biopsies gave a

denitive diagnosis.

Discussion

We were able to show that the automated system works well

and could provide technical and diagnostic success rates

similar to those obtained with the manual method. Also,

we found that the automated device decreased the number

of needle position adjustments and thereby minimized the

procedure time. There was no signicant dierence in the

incidence of complications with the two methods.

Abstract

Automated guiding apparatuses for CT-guided biopsies are now available. We report our experience with an indigenous system

to guide lung biopsies. This system gave results similar to those with the manual technique. Automated planning also appears to

be technically easier, it requires fewer number of needle passes, consumes less time, and requires fewer number of check scans.

Key words: Automated / manual planning; CT-guided needle lung biopsy

DOI: 10.4103/0971-3026.54883





Clinical Publication - 7L A B O R A T O R Y I N V E S T I G A T I O N

Comparison of CT Fluoroscopy-Guided Manual and CT-Guided

Robotic Positioning System for In Vivo Needle Placementsin Swine Liver

F. Cornelis • H. Takaki • M. Laskhmanan • J. C. Durack • J. P. Erinjeri •

G. I. Getrajdman • M. Maybody • C. T. Sofocleous • S. B. Solomon •

G. Srimathveeravalli

Received: 25 July 2014 / Accepted: 8 September 2014

Springer Science+Business Media New York and the Cardiovascular and Interventional Radiological Society of Europe (CIRSE) 2014

Abstract

Purpose To compare CT fluoroscopy-guided manual and

CT-guided robotic positioning system (RPS)-assisted nee-

dle placement by experienced IR physicians to targets in

swine liver.

Materials and Methods Manual and RPS-assisted needle

placement was performed by six experienced IR physicians

to four 5 mm fiducial seeds placed in swine liver (n = 6).

Placement performance was assessed for placement accu-

racy, procedure time, number of confirmatory scans, needle

manipulations, and procedure radiation dose. Intra-modal-

ity difference in performance for each physician was

assessed using paired t test. Inter-physician performance

variation for each modality was analyzed using Kruskal–

Wallis test.

Results Paired comparison of manual and RPS-assisted

placements to a target by the same physician indicated

accuracy outcomes was not statistically different (manual:

4.53 mm; RPS: 4.66 mm; p = 0.41), but manual place-

ment resulted in higher total radiation dose (manual:

1075.77 mGy/cm; RPS: 636.4 mGy/cm; p = 0.03),

required more confirmation scans (manual: 6.6; RPS: 1.6;

p\ 0.0001) and needle manipulations (manual: 4.6; RPS:

0.4; p\ 0.0001). Procedure time for RPS was longer than

manual placement (manual: 6.12 min; RPS: 9.7 min;

p = 0.0003). Comparison of inter-physician performance

during manual placement indicated significant differences

in the time taken to complete placements ( p = 0.008) and

number of repositions ( p = 0.04) but not in other study

measures ( p[ 0.05). Comparison of inter-physician per-

formance during RPS-assisted placement suggested statis-

tically significant differences in procedure time ( p = 0.02)

and not in other study measures ( p[ 0.05).

Conclusions CT-guided RPS-assisted needle placement

reduced radiation dose, number of confirmatory scans, and

needle manipulations when compared to manual needle place-

ment by experienced IR physicians, with equivalent accuracy.

Keywords Image-guided biopsy Navigation

system Robotic guidance Needle placement

Introduction

Different needle guidance and placement assistance sys-

tems have been developed for percutaneous image-guided

procedures in the thorax and abdomen to improve targeting

accuracy independent of physician experience, and to

reduce radiation exposure to the physician and the patient.

Such assistance systems include optical [1, 2], electro-

magnetic navigation [3–5], laser overlay [6], US guided

[7], fluoroscopy guided [8], and robotic systems [9–19].

The robotic approach offers several advantages over other

assistance systems including: (1) lack of line of sight

restrictions encountered in optical systems, (2) the ability

to function unaffected by the presence of ferrous materials

that may interfere with electromagnetic navigation

F. Cornelis

H. Takaki

J. C. Durack

J. P. Erinjeri

G. I. Getrajdman M. Maybody C. T. Sofocleous

S. B. Solomon G. Srimathveeravalli (&)

Interventional Radiology Service, Department of Radiology,

Memorial Sloan-Kettering Cancer Center, 1275 York Avenue,

New York, NY 10065, USA


F. Cornelis

Department of Radiology, Pellegrin Hospital, Place Amelie Raba

Leon, 33076 Bordeaux, France

M. Laskhmanan

Perfint Healthcare Inc, Chennai, Tamil Nadu, India

1 3

Cardiovasc Intervent Radiol

DOI 10.1007/s00270-014-1016-9





systems, and (3) the presence of a robust platform for

guiding large diameter needles [20]. It has also been sug-

gested that the use of robotic assistance during needle

placement can help minimize the radiation exposure to

operators and patients during CT fluoroscopy-guided

interventional procedures [17, 20–27]. At the same time,

the use of robotic guidance may also reduce the number of

needle adjustments required to reach a target, thereby

reducing patient complications such as bleeding [28].

The efficacy of robotic assistance for needle placements in

the thorax or abdomen has been typically evaluated through

experimental placements performed on phantoms [15], ani-

mals [29], or patients [26] without comparison to manual

placements to similar targets by experienced IR physicians

using standard technique. We address this knowledge gap by

comparing CT Fluoroscopy-guided manual and CT-guided

RPS-assisted needle placement by experienced IR physician

when targeting small in vivo targets in liver.

Materials and Methods

Animal Use

Six female swine (35–50 kg) were used in experiments

following an experimental protocol approved by the Insti-

tutional Animal Care and Use Committee. Animals were

sedated with intravenous tiletamine hydrochloride and zo-

lazepam hydrochloride (6 mg/kg; Telazol; Fort Dodge

Animal Health, IA). General anesthesia was maintained

with inhaled isoflurane (1.5–3 % Aerrane; Baxter Health-

care, Round Lake, IL) after endotracheal intubation. The

swine was positioned into the CT scanner (Lightspeed A6,

GE Healthcare, Princeton, NJ) in decubitus position. Prior

to each study an experienced IR physician who was not the

study participant placed four metal fiducial markers (5 mm

long, 18G in diameter) in each of the four major lobes of

swine livers. The seeds were evenly spaced out in depths

within the range of 50–120 mm (4 seeds per animal, 24

seeds in total). Each IR physician participating in the study

worked on a single animal. All RPS-assisted needleplacements were performed using breath-holds during

image acquisition for planning and during placement of the

needle. The breath-hold was facilitated using a muscle

paralytic (Rocuronium; 1.2 mg/kg) administered intrave-

nously before suspending breathing on the ventilator. All

animals studied were euthanized after the procedure.

Experimental Methods for Manual Needle Placement

Six IR physicians with at least 8 years of experience in

independently performing image-guided needle placement

participated in this study. A baseline non-contrast CT was

performed (LightSpeed 16; GE Healthcare, Milwaukee,

Wis), and the study participant was allowed to view this

scan to evaluate the seed locations. The IR physician was

informed on the metrics that were being gathered for the

study, and was asked to place the needle tip as close as

possible to the seed being targeted, while treating each

needle placement as a separate procedure. The procedures

were timed starting with the acquisition of the planning

scan and ending when the IR physician confirmed that they

were satisfied with the needle location. CT fluoroscopy

guidance was used to manually target the markers using

100 or 150 mm length coaxial needles (18G biopsy nee-

dles, E-Z-EM Inc, Westbury, NY). The four manual

placements were performed sequentially, and preceded the

four RPS-assisted placements.

Experimental Methods for RPS-Assisted Placement

CT-guided RPS-assisted needle insertion was performed

using a commercially available platform (Perfint Health-

care Inc., Chennai, India.). The RPS resides on a wheeled

cart and consists of two components, a software module

that assists in the planning of needle placements for biopsy

and ablations, and an articulated 5 of freedom robotic arm

with a disposable needle guide mounted on its end effector.

The cart is docked on a metal plate mounted on the floor

beside the CT table, after which fresh CT scan (1.25 mm

slice thickness, 20 images) acquisitions were performed

with breath-hold to plan for each RPS-assisted needle

placement. The RPS’s onboard computer received the

DICOM formatted images from the CT console via an

ethernet cable, and was used for planning and navigation

using the onboard software (Fig. 1).

Prior to commencing the RPS-assisted needle placements,

the IR study physician was oriented to the RPS system and

given an overview of the workflow for planning and place-

ment using this system. Without specific training or practice

sessions for using the RPS, the participant was then asked to

use planning sequence to determine an entry point (needlepuncture site on skin surface) and the target point (center of

the fiducial) for needle placement. The participant then used

interactive drop down menus to select the appropriate needle

length (100 or 150 mm) for carrying out the plan. The

angulations of the needle, the depth of the lesion as well as

the needle trajectory path were calculated by the workstation

and shown on the treatment plan (Fig. 2A). The software

onboard the RPS provided the physician visual feedback on

critical structures within the vicinity of the planned trajectory,

and the physician planning the placement was ultimately

responsible for choosing path that avoided critical organs or

bone across the needle trajectory.

F. Cornelis et al.: CT Fluoroscopy-Guided Manual and CT-Guided RPS

1 3




Computed Tomography guided percutaneous

liver biopsy using a robotic assistance device - a

corpse study.

Boris Schulz, M.D.; Katrin Eichler, M.D.; Firas Al-Butmeh, M.D.; Claudia Frellesen,

M.D.; Thomas Vogl, M.D.; Christoph Czerny, M.D.; Stephan Zangos, M.D.

Department of Diagnostic and Interventional Radiology, University Hospital Frankfurt, Goethe-University,

Frankfurt am Main, Germany

Abstract

Objective:

To investigate a robot assistance device for CT guided percutaneous liver biopsy.

Materials and Methods:

The liver of a corpse was equipped with target dummies. Four radiologists used a 16G needle to perform

biopsy of the target region in standard free hand technique and then by using a robot system which allows

planning and aligning the trajectory path. Accuracy in terms of needle tip deviation, time efficiency and

radiation exposure in terms of Effective dose for the radiologists were measured.

Results:

For in plane procedures there was no significant benefit in accuracy when using the robot

versus standard technique (4mm vs. 5.6mm, p=0.11), timely effort was worse (443sec vs. 405sec,

p=0.64). For angulated punctures a needle tip of 3.7mm was measured by using the robotic device (vs.

10.8mm, p<0.01), mean biopsy duration was 490sec (vs. 900sec, p<0.01). Mean radiation exposures in

freehand technique were 2.4 μSv (in-plane procedures) and 10.8 μSv (oblique procedures, the robotic

assisted procedures were performed without additional image guidance.

Conclusion:

The proposed robotic assistance device may be superior for angulated interventions regarding accuracy

and timely effort. Furthermore the zero radiation exposure for the interventional Radiologist will be a

significant benefit.





Robot assisted percutaneous placement of K-wires during minimal invasive

spinal interventions

Christoph Czerny1, Katrin Eichler 2, Boris Schulz2, Christof Schomerus3,

Thomas J. Vogl2, Ingo Marzi1 and Stephan Zangos2

1Department of Trauma Surgery, University Hospital Frankfurt, Goethe-University

Frankfurt, Frankfurt am Main, Germany, 2Department of Diagnostic and

Interventional Radiology, University Hospital Frankfurt, Goethe-University, Frankfurtam Main, Germany, 3Fachbereich Medizin der Goethe-Universität, Dr.

Senckenbergische Anatomie, Frankfurt am Main, Germany

Address correspondence to: Stephan Zangos, MD, PhD

Department of Diagnostic and Interventional

Radiology, University Hospital Frankfurt, Goethe-

University,

Theodor-Stern-Kai 7, D-60590 Frankfurt am Main,

Germany

E-mail: [email protected]

Keywords: computer assisted surgery, malpositioning, minimal invasive spine

intervention, precision, timely effort, radiation exposure

List of Abbreviations: CT, Computed Tomography; K-wire, Kirschner wire;





Abstract

Objective To report our experience using the new robot assistance device MAXIO

for needle guidance during spine interventions.

Methods A computed tomography was acquired with a modern CT device (Definition

AS, Siemens Healthcare, Germany). Reconstruction of CT-images and planning of

the needle path were performed using the integrated planning computer of MAXIO.

The needle holder of MAXIO acted as a guide during the insertion of the K-wires.

Twenty-four percutaneous K-wires were placed in the pedicles at T2, T7-T12 and L1-

L5 in a cadaver specimen. Post-procedure CT scans were obtained to confirm the

accuracy of the K-wire placement.

Results All K-wire placements were successfully performed. The mean planning time

was 2:53 min, mean positioning time of MAXIO was 2:04 min and mean placement

time of the K-wires was 2:15 min. The mean total intervention time was 7:12 min per

pedicle.

A mean deviation of 0.5 mm in the z-axis and 1.2mm in the x-axis between the

planned path and the placed K-wire with a mean path length of 8.1 cm was

documented.

Conclusions Our results demonstrate the potential of MAXIO for a safe and

accurate percutaneous placement of K-wires in spine interventions without radiation

exposure to the attending staff.



© C

o p y r i g h t 2 0 1 4 P e r fi n t H e a l t h c a r e C o r p o r a t i o n .

A l l r i g h t s r e s e r v e d .

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