Progression of Hepatic Hypovascular Nodules with Hypointensity in the Hepatobiliary Phase of Gd-EOB-DTPA-enhanced MRI in Hepatocellular Carcinoma Cases

OBJECTIVE: We investigated the possible factors for predicting the future progression to hepatocellular carcinoma (HCC) from hypovascular nodules detected in the hepatobiliary phase of gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid-enhanced magnetic resonance imaging (Gd-EOB-DTPA-MRI). METHODS: A total of 91 hypovascular nodules detected by Gd-EOB-DTPA-MRI in 28 patients without any past history of treatment for HCC were retrospectively examined. The nodules were categorized into those with and without HCC progression, then comparisons were made to identify any factors possibly related to a progression to HCC in each case. In addition, we performed a receiver operating characteristics (ROC) analysis to determine the cut-off value for the initial nodule size for predicting HCC progression within 12 months. RESULTS: The observation period of the 28 patients was 1,172.6±95.6 (mean±standard error) days. The number of hypovascular nodules that changed to hypervascular ones was 15 (16.5%), and the cumulative incidence of hypervascular transformation was 7.1% at 12 months and 12.7% at 24 months. Of all 91 hypovascular nodules, 33 in 18 patients were diagnosed as HCC based on hypervascular transformation and/or size enlargement, while the remaining 58 did not progress to HCC. There was no significant difference regarding the background characteristics between the HCC progressed and non-progressed groups according to a multivariate analysis, or between the patients who had nodules that progressed to HCC and those with nodules that did not progress to HCC. Regarding HCC progression at 12 months, the area under the ROC (AUROC) had a level of 0.745 and showed that an initial nodule cut-off size of 9.5 mm (sensitivity, 57.9%; specificity, 87.3%) was predictive. CONCLUSION: In patients without a past HCC treatment history, it is difficult to determine whether hypovascular nodules have a high risk of progression to HCC based on background factors alone.