Coronary Imaging
Dr. Mahendra
Cardiology,JIPMER
Coronary angiography
Gold standard for evaluating CAD
Guide both PCI and CABG
Provides highly useful picture of the vessel lumen
Indirect information about the arterial wall
2
57/M ,old IWMI, CSA 3
4
5
IVUS6
7
8
FFR = 0.91
LM STENTING DEFERRED !!!
9
10
11
12
Anatomical assessment
Intracoronary imaging
Functional assessment
FFR
?
13
Muller et al., The Year in Intracoronary ImagingJ A C C : C A R D I O V A S C U L A R I M A G I N G ,
V O L . 3 , N O . 8 , 2 0 1 0
A U G U S T 2 0 1 0 : 8 8 1 – 9 1
14
IVUS Image integrity should be
checked before inserting
No coronary preparation is needed
Iv Heparin 5000-10000U ;
Ic NTG 100-200 µ
Standard coronary interventional techniques and equipment (guiding catheter and 0.014 inch angioplasty guidewire)
Automated pullback device (usually at a rate of 0.5–1.0 mm/s for any length) or by manual operator pull back
15
Characteristic three-layered
appearance (bright-dark-bright)
Spillover effect (blooming)
Normal vessel – intima maynot be
seen
Atherosclerotic vessel – media
may not appear distinct
20-45 MHz
100-200 µ resolution
4-8 mm beam penetration
16
17
Minimal lumen dimension
Maximal lumen dimension
18
Lumen area
Total vessel area
Plaque area
Neointimal hyperplasia
Plaque burden = plaque area
total vessel area
19
20
Reference segment – most normal looking (largest
lumen with smallest plaque burden) within 10 mm
from the lesion with no intervening side branches
Arterial remodelling (Glagov et al)
-Positive remodelling (adaptive);RI >1
-Negative remodelling(constrictive);RI<1
-Intermediate remodelling
Remodelling Index = EEM surface area (lesion site)
EEM surface area (reference site)
21
22
Gray scale IVUS
Soft plaque – echogenicity less than the
surrounding adventitia
Fibrous plaque – intermediate echogenicity
between those of soft plaques and highly
echogenic calcium plaques
Calcified plaques – high echogenicity with
acoustic shadowing (superficial or deep)
23
Plaque characterization24
25
Dark green - fibrous
Light green - fibrofatty
White- calcium
Red - necrotic
Green – fibrous
Yellow – dense fibrous
Blue- lipid pool
Red- calcium
Green - fibrotic
Yellow- lipidic
Light blue- calcium
Pink - necrotic
26
Abnormal lesion morphology27
Interventional applications Angiographically intermediate lesions
Calcified lesions – degree and location
High risk lesions for distal embolisaton –lipid pool and thrombus containing
Left main lesions (<6 mm2) – LITRO
Bifurcation lesions
CTO
ISR
Optimal device sizing (angiographic normal reference segment vs IVUS reference segment) – CLOUT, BEST, STILLR
Opimal stent expansion – CRUISE, AVID
Acute stent problems ( Incomplete expansion, malapposition, marginal tears )
28
Vulnerable plaque
Hypoechoic plaques without a well formed fibrous
caps
29
Plaque rupture
Hypoechoic cavity within the plaque is connected
within the lumen and a remnant of fibrous cap is
observed at the connecting site
Often eccentric, less calcified, large plaque burden,
positively remodelled, and a/w thrombus
Extensive positive remodelling – most consistent
feature reported in GS-IVUS predicting plaque
instability
30
Ability of IVUS to predict future coronary events
- PROSPECT trial
Three vessel VH-IVUS in 697 ACS patients
Three baseline IVUS characteristics that
independently predicted future events
1) Plaque burden > 70 %
2) TCFA
3) MLA < 4 mm2
31
Safety
Most frequent acute complication – transient
coronary spasm 1-3%
Major complications <0.5% (Dissections,
thrombosis, abrupt closure)
Batkoff BW, Linker DT, Safety of intracoronary ultrasound:
data from a Multicenter European Registry, Cathet
Cardiovasc Diagn, 1996;38:238–41.
32
Limitations Extensive calcification at lesion site leads to large
acoustic shadowing and difficulty in interpreting the
exact size of the vessel
Ghost images - Occurs when structures of high
echogenicity are imaged (eg Calcium, stent struts).
Appear on the side of the transducer that is opposite
the bright structure being imaged.
33
A case with spontaneous dissection. Optical coherence
tomography (C) visualized spontaneous dissection that could not
be found with angiography (A) or intravascular ultrasound (B).
34
OCT
Optical analogue of IVUS
Significantly higher resolution (10 times more) but
lesser penetration
Uses near infrared rays- 1.3 microns
OCT measures the time delay of the light that is
reflected or backscattered from tissue, and that is
collected by the catheter, by using a technique
known as interferometry.
35
IMAGING WIRE AND CATHETER
36
TD- OCT FD-OCT
• Injecting continuous saline/contrast flushes through theguiding or delivery catheters.
•Proximal balloon occlusion ofthe vessel with distalsaline/contrast injection.
•Time-consuming
• Require a high degree ofoperator expertise
•FD OCT systems do not requireproximal occlusion
•Bolus injection of saline, contrast, orotherSolution, injected at rates of 2 to 4ml/s, and an automated 20 mm/spullback within a monorail rapidexchange catheter allows imaging of a6-cm-long coronary segment during a3-s injection
37
NORMAL ARTERIAL WALL IN OCT38
1)Fibrous plaques -- homogeneous, signal-rich regions
2)Fibro - calcific plaques --- signal-poor regions/ sharp borders
3)Lipid-rich plaques ---signal-poor regions with diffuse borders
39
40
Ex vivo validations --- OCT superior to conventional andintegrated backscatter IVUS for the characterisation ofcoronary atherosclerotic plaque composition.
In vivo, OCT is superior for the identification of lipidpools
Thin capped fibroatheromas (TCFA) - defined pathologically by the triad of:
Lipid core.
Fibrous cap with a thickness < 65 micron m.
Cell infiltration of the fibrous cap.
OCT for in vivo assessment of fibrous cap thickness ----Unique ability to image superficial detail.
OCT can quantify macrophages within the fibrous cap.
41
42
43
OCT can identify intracoronary thrombus and plaque rupture with high accuracy.
44
OCT AND PCI Fine resolution at a superficial depth, OCT allows a
uniquely detailed image of the effects of stent
implantation on the vessel wall.
OCT allows:
Examination of the target vessel both pre- and post-
intervention
Defining stent struts readily
Tissue prolapse between stent struts immediately
(97.5%)
Tissue characterization of plaque before and after
stent placement
Intrastent dissection (86.3%)
45
3-point classification defines stent strutapposition.
Embedded ----- the leading edge is buriedwithin the intima by more than one-half itsthickness
Protrusion --- stent strut is apposed but notembedded
Malapposed ---- there is no intimal contact
46
47
Primary imaging modalities for follow-up evaluation of several bioabsorbable vascular scaffolds (BVS), which are being studied in clinical trials (ABSORB)
OCT has been increasingly used as an endpoint in clinical trials of newer generation DES (LEADERS)
OCT helps to predict no reflow post-PCI, based on the presence of TCFA
48
49
50
SAFETY
The relatively low energy used in OCT (5.0–8.0 mW)
does not cause functional or structural damage to the
coronary tissue.
Use of a contrast bolus in coronary preparation is a
concern but studies have shown that no patients
suffered contrast-induced nephropathy,
Small risk of coronary spasm and electrocardiogram
(ECG) changes during contrast administration.
51
LIMITATIONS
Need to displace blood or dilute the hematocrit, either withsaline or contrast flush injection, or a combination of the two.
Shallow image penetration of 1 to 2.5 mm. This preventsassessments of cross-sectional plaque area ---- OCT has onlya limited role in the assessment of left main stem andSaphenous vein graft atherosclerosis severity.
The differentiation of calcific areas from lipid pools can beproblematic . both result in a low attenuation signal.
Imaging of Left main ostium
Imaging in patients with decreased creatinine clearance
Image artifacts
52
53
54
The 2011(ACCF)/(AHA)/ (SCAI)
guidelines for PCI
1) IVUS for the evaluation of angiographically indeterminate left main lesions and angiographically indeterminate (50–70 % stenosis) non-left main coronary lesions (Class IIa LOE B)
2) IVUS to evaluate the aetiology of stent restenosis and stent thrombosis (Class IIa, Level of Evidence C).
3)The routine use of IVUS for evaluation of lesions when PCI is not planned was given a Class III recommendation
4) Currently neither the American nor European (ESC) guidelines provide recommendations for the routine use of OCT in clinical practice
5) More recent guidelines published in February 2014 by NICE suggest that the evidence on the safety of OCT to guide PCI showed no major concerns
IVUS reveals need of postdilatation
55
CONCLUSION IVUS and OCT - useful image guiding tools during stent
implantation.
Intracoronary imaging may prove to be useful in reducing
complications by 1) improving the techniques of stent sizing and
placement, 2) identifying the role of necrotic-core plaque as a cause
of stent complications, and 3) assessing stent coverage and
thrombosis.
OCT - higher resolution and adds more information particularly
distinguishing thrombus formation, coronary dissection and
incomplete stent apposition following implantation.But not clear
whether this additional information helps to improve patient outcome
At present, IVUS remains the more trusted and validated imaging
modality and is the first-choice modality to guide optimal stent
implantation.
56
Thank you !!!
57
A bend in a mechanical IVUS
catheter due to severely
angulated lesions may cause
unnecessary friction and
generate Non-Uniform
Rotational Distortion
(NURD), which results in a
smeared image
Ring-down artifact -- Caused by
transducer oscillation filling the
area immediately adjacent to the
catheter with noise, making this
area unavailable for imaging. Seen
as bright halo of variable thickness
surrounding the catheter.
58
Residual blood “sunflower” effect or“merry-go-round” effect .
Saturation Artifact
59
Bubble Artifact
Fold-over Artifacts
Sew-up Artifacts
60
Top Related