Hepatocellular Carcinoma (hcc) with Portal Venous Tumor Thrombosis (pvtt) Response to Yttrium-90 Radioembolizaion Evaluated by Functional Mri

Introduction: Patients with hepatocellular carcinoma (HCC) and portal venous tumor thrombosis (PVTT) are not candidates for curative surgical resection; therefore liver-directed therapies would be alternative treatment, such as yttrium-90 (Y) radioembolization [1]. Earlier monitoring of advanced HCC response to treatment should influence the strategies of therapy. Moreover, detection of PVTT response to therapy is essential to predict survival rate as PVTT is one of the most important independent risk factors for higher recurrence rates and worse survival rates. However, changes in tumor cellularity and vascularity as initial responses to treatment are not be compatible with the criteria of World Health Organization (WHO) and Response Evaluation Criteria in Solid Tumors (RECIST) which is based on anatomic images [2]. Contrast-enhanced magnetic resonance image (MRI) can detect changes in the extracellular space and tumor vascularity by percentage enhancement at arterial and portal venous phases imaging. Enhancement can be induced by viable tumor, whereas necrotic tumor is nonenhancing. Diffusion-weighted imaging (DWI) is a measure of water motion determined by cellularity and integrity of the cell membrane. Contrast-enhanced MRI and DWI identified as functional MRI have been proposed to demonstrate tumor cells response after regional liver treatment. Prior studies showed that an increase in apparent diffusion coefficient (ADC) values and a decrease in percentage enhancement indicate tumor response to treatment [3, 4]. The goal of this study was to evaluate the hypothesis that DWI can assess HCC and PVTT response to Y radioembolization and compare DWI with contrast-enhanced MRI.