Hypovascular Hepatic Nodules Showing Hypointense on the Hepatobiliary-Phase Image of Gd-EOB-DTPA-Enhanced MRI to Develop a Hypervascular Hepatocellular Carcinoma: A Nationwide Retrospective Study on Their Natural Course and Risk Factors

Objective: We aimed to investigate the natural outcome of nonhypervascular lesions detected in the hepatobiliary phase of gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced MRI by performing a longitudinal study retrospectively enrolled in a nationwide manner. Methods: Between February 2008 and March 2011, 224 patients with 504 nodules that were diagnosed as non-hypervascular by imaging were recruited from institutions that participated in the present study. We examined the natural outcome of nonhypervascular lesions and evaluated the risk factors. Results: Of the 504 nodules, 173 (34.3%) showed hypervascular transformation. The overall cumulative incidence of hypervascular transformation was 14.9% at 12 months and 45.8% at 24 months. Multivariate analysis using the Cox regression model revealed previous treatment history for hepatocellular carcinoma (HCC; relative risk = 1.498; p = 0.036, 95% CI 1.03-2.19) and hyperintensity on T2-weighted images (relative risk = 1.724; p = 0.015, 95% CI 1.11-2.67) were identified as independent factors for hypervascular transformation. Conclusions: Patients who have a previous treatment history for HCC and with hypointense nodules showing hyperintensity on T2-weighted images need careful follow-up because of the high incidence of hypervascular transformation. (C) 2013 S. Karger AG, Basel