الفهرس 
Anatomy of the liverOnly 14 pages are availabe for public view
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Abstract
Purpose: To evaluate the role of dynamic contrast enhanced (DCE) and
diffusion weighted MRI in the assessment of response to treatment and
detection of residual tumor viability of hepatocellular carcinoma after
trans catheter arterial chemoembolization (TACE) and radiofrequency
ablation (RFA).
Subjects and methods: Pre contrast T1, in and out phase, T2, T2
SPAIR, respiratory triggered diffusion weighted MR images (b factor
400, 800 s/mm2) and dynamic contrast enhanced MRI with post
processing subtracted images and color mapping obtained in 50 patients
with hepatocellular carcinoma (25 post RFA and 25 post TACE).
Dynamic post gadolinium-enhanced & Diffusion-weighted MR images
were assigned confidence levels for post interventional HCC
residue/recurrence and we categorize the patients into resolved and
unresolved groups. The sensitivity, specificity, PPV, NPV and accuracy
for both the dynamic and the DWI images in post RFA & post TACE
patients were calculated. Apparent diffusion coefficients (ADCs) were
calculated for entire treated zone, malignant lesions and perilesional
reactive parenchymal changes for the different study groups.
Results: In post TACE lesions, dynamic MRI had a sensitivity of 90%,
a specificity of 100%, a positive predictive value of 100 %, a negative
predictive value of 93.8 % and an accuracy of 96% compared to 100%,
66.6%, 66.6%, 100% and 80% respectively of diffusion weighted
imaging. In post RFA lesions, dynamic MRI had a sensitivity of 100 %,
a specificity of 92.9%, a positive predictive value of 91.7 %, a negative
predictive value of 100% and an accuracy of 96% compared to 100%,
71.4%, 73.3%, 100% and 84% respectively of diffusion weighted
imaging. The mean ADC value of the recurrent or residual malignant
lesions was significantly lower than that of the post interventional
perilesional parenchymal changes (P value 0.001**).
Conclusion: Dynamic contrast enhanced MRI is superior to diffusion
weighted MRI in evaluating HCC response to locoregional therapy. DWI
helps to improve the sensitivity for detecting marginal tumor recurrence
of HCCs after locoregional therapy, especially in indeterminate hyper
vascular lesions without definite venous washout, yet, DWI has lower
specificity compared to dynamic MRI with increased false positives due
to intra-lesional hemorrhage and perilesional parenchymal changes
causing diffusion restriction and decreasing PPV. Dynamic study with
complementary diffusion imaging and ADC measurements allow better
tissue characterization and help in effective monitoring of tumor response to locoregional therapy.