Mass-forming Intrahepatic Cholangiocarcinoma: Diffusion-weighted Imaging as a Preoperative Prognostic Marker

Purpose: To assess the value of diffusion-weighted (DW) imaging as a prognostic marker in preoperative evaluation of patients with mass-forming intrahepatic cholangiocarcinoma (ICC). Materials and Methods: This retrospective study was approved by the institutional review board, and the informed consent requirement was waived. A total of 91 patients who underwent hepatic resection and DW imaging for mass-forming ICC were included. Two radiologists evaluated the degree of diffusion restriction of the tumors by using qualitative (visual) interpretation combined with quantitative analysis by volumetric evaluation of the whole tumor on DW images. Patients were classified into two groups: those in whom less than one-third of the tumor showed diffusion restriction (group 1) and those in whom more than one-third of the tumor showed diffusion restriction (group 2). Imaging findings in tumors were compared with pathology findings. Disease-free and overall survival rates were compared between the two groups by using the Kaplan-Meier method with the log-rank test. Results: There were 43 patients in group 1 and 48 patients in group 2. The 1-and 3-year disease-free survival rates were 30% and 16%, respectively, in group 1 and 75% and 64%, respectively, in group 2 (P <,.001). The 1- and 3-year overall survival rates were 77% and 26%, respectively, in group 1 and 92% and 67%, respectively, in group 2 (P =.001). Multivariate analysis revealed that diffusion restriction (P =.024), differentiation (P =.030), and intrahepatic metastasis (P =.001) were independent prognostic factors for overall survival. Conclusion: The degree of diffusion restriction on DW images may be a prognostic marker in preoperative evaluation of patients with mass-forming ICC. (C) RSNA, 2016