Does the Diffusion Weighted Images and Subtration MRI of Hepatocellular Carcinoma has a Role in Predicting Outcome of Transarterial Chemoembolization?

Abstract
Background: Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide, and has a poor prognosis unless treated. Ablative therapies are promising treatment options for patients who are not eligible for surgery.
Aim of Study: Is to evaluate the predictive values of diffusion-weighted imaging (DWI) and Subtration MRI in evaluating the efficacy of transcatheter arterial chemoembol-ization (TACE) in treatment of patients with hepatocellular carcinoma (HCC).
Patients and Methods: This study included 30 patients with pathologically proven HCC (38 HCC lesions) who were referred to the Radiology Department of Ain Shams University Hospitals and National Liver Institute, Menofiya University for post therapeutic assessment after transarterial hepatic chemoembolization. The study was carried on over a period of 12 month (from August 2017 to August 2018). Patients' ages ranged from 59 to 73 with a mean of age 59.6 years. Of the 30 patients only 6 were females and 24 were males.
Results: We found that dynamic study is the gold standard in detection of recurrent lesions. Well defined nodular en-hancement, thick irregular marginal enhancement or gross enlargement of the lesion with arterial phase enhancement and contrast wash out were considered positive for malignancy. Ill-defined persistent enhancement or well defined rim marginal enhancement were considered benign post ablation changes. We found that subtraction technique was essential in differ-entiation between the normal hyperintense T1 signal of the ablation zone and arterial enhancement of the lesion. The high signal intensity seen in T1 images post TACE was explained by haemorrhagic coagulative necrosis. Subtraction imaging is ideally suited for such a role where the unenhanced T1-weighted sequence is subtracted from the identical contrast enhanced sequence.
Conclusion: We conclude that in evaluation of HCC after TACE, ADC calculated at DWI had weaker correlation to tumor necrosis degree than did findings with subtraction contrast-enhanced MRI. However, there was no difference between both methods in diagnosis of complete tumor necrosis.
We suggest that whenever possible, gadolinium contrast enhancement and subtraction imaging be used for assessment of tumor necrosis after TACE.