Oncological Applications of Dual Energy CT in the Abdomen
Transcript of Oncological Applications of Dual Energy CT in the Abdomen
HARVARD
MEDICAL SCHOOL
MASSACHUSETTS
GENERAL HOSPITAL
Oncological Applications of
Dual Energy CT in the Abdomen
Avinash Kambadakone, MD FRCR
Aims and Objectives
• To review the technical aspects of DECT with particular focus on
oncology and tips for protocol optimization
• Discuss the potential role and limitations of DECT in oncology
• Describe our experience with integration of DECT in oncologic imaging
practice
• Case-based discussion on clinical value of DECT in cancer patients
I- I+ I- I+
SECT: Limitations
Need for non-contrast scans
Presence of Artifacts
(Beam hardening, metal
streak artifacts)
Post treatment assessment
Small lesion evaluation
Need for multiphasic scans
Courtesy: Dushyant Sahani, MD
DECT: Advantages in Oncology 1. Improved lesion Characterization
a. hemorrhagic cysts vs solid renal masses
b. hepatic cysts vs hypodense metastases
2. Improve lesion detection
a. Virtual precontrast (water density) images
b. Reduced beam hardening
c. Low kVp/ monochromatic Kev images
3. Reduce dose
a. Eliminate non-contrast exams
b. Decrease follow-up CT of indeterminate lesions
4. Metal Artifact Reduction
DECT in Oncology
• Tumor Detection
• Tumor Characterization
• Treatment Planning
• Monitoring Treatment Response
DECT: Tumor Detection • Low energy virtual mono-chromatic images improve detection of both
hypervascular and hypovascular lesions
• Iodine-specific maps improve detection of hypovascular lesions in the liver,
pancreas and kidney
• DECT improves depiction of hepatocellular carcinoma and hypervascular liver
metastases
• Improves detection and staging of pancreatic cancer
140 keV
DECT- Improved Detection
• DECT allows improved detection of small hypervascular HCC lesions
• Low keV and iodine images can be exploited to enable superior lesion
evaluation
70 keV 50 keV
Improved visualization of multifocal HCC on low keV images
CECT
MD iodine MD iodine
DECT - Improved Detection
Iodine specific images improve detection of hypovascular lesions
DECT: Tumor Characterization
• Iodine specific images demonstrate iodine in tissues and aid in
lesion characterization
• Iodine specific images can help differentiate renal cysts from
solid neoplasms
• DECT allows characterization of adrenal nodules
• Iodine maps may help differentiate between blood clot and
tumors e.g. bland versus tumor thrombus
Small
cyst
MD Iodine
Renal
mass
TNC Iodine map TNC CECT
DECT: Tumor Characterization
Virtual unenhanced images and Iodine images, helps differentiate
renal masses from cystic lesions
DECT: Treatment Planning
Adenocarcinoma of the pancreas: Hypoattenuating lesion in the tail of the pancreas
(arrow) with margins unclearly defined in CECT image. The VMC image at 50 keV
and iodine map can better define the margins of the lesion as well as its relationship
with vessels, contributing to a better treatment planning.
CECT 50 keV Iodine map
Coursey, C. A. et al. Radioghraphics 30(4), 1037–1055, Silva, A. C et al. Radiographics 31(4), 1031–1046, Kulkarni N et al. JVIR 2012
DECT: Monitoring Response
Iodine maps obtained from dual energy acquisition allows detection of enhancement in
ablation zone to identify residual tumor/ recurrence in HCC
Iodine map Color overlay image
Dual energy CT
• Qualitative and quantitative
iodine extraction from processed
DECT data sets enables more
accurate detection of
residual/recurrent tumor.
• Vascular or parenchymal
complications
• Quantitative response monitoring
using tissue iodine values
HCC: RFA + TACE
HCC: post RFA
• Establish the image series to be sent to PACS
Our Practice Cancer follow up protocol CT
Limit DECT scans/day to cause minimal impact on workflow
140kVp (5mm) 65keV (5mm) MD-W (5mm) MD-I (5mm) Cor/Sag (3mm)
– Cancer follow up scans
– Renal-mass
– CTU
– Liver (HCC/hypervascular tumors)
– Pancreatic mass/staging
Oncology DECT Protocols
• Needs specialized hardware and software (Cannot upgrade
a SECT)
• Cost
• Accessibility
• Workflow constraints
• Patient body habitus
Oncology DECT Protocols