1 All authors: Department of Radiology, Kawasaki Medical School, 577 Matsushima, Kurashiki, Okayama, 701-0192, Japan.
OBJECTIVE. The purpose of our study was to evaluate the process and frequency of newly developed hypervascular hepatocellular carcinoma (HCC) in serial gadoxetic acid-enhanced MRI examinations in patients with chronic liver disease during clinical follow-up periods. MATERIALS AND METHODS. After review of 341 MRI examinations in 100 patients with chronic liver diseases who underwent gadoxetic acid-enhanced MRI at least twice during the observation period, 32 newly developed hypervascular HCCs in 14 patients were retrospectively evaluated. Serial MRI examinations before detecting hypervascular HCC were evaluated to determine whether hypervascular HCC showed the presence of a hypoin-tense nodule on the hepatobiliary phase and hypovascularity (high-risk nodule) before hyper-vascularization. The size of newly developed hypervascular HCCs and the duration of hyper-vascularization from initial detection of a high-risk nodule were compared between HCCs with and without the presence of a high-risk nodule. RESULTS. Eleven (34.4%) of 32 newly developed hypervascular HCCs had the presence of high-risk nodule before hypervascularization. The size of newly developed hypervascular HCCs was significantly smaller in HCC with high-risk nodule presence (mean, 9.5 mm) than in HCC without the presence of high-risk nodule (mean, 16.4 mm) (p = 0.004). In hypervascular HCCs with high-risk nodule presence, the mean duration of hypervascularization from initial high-risk nodule was 330.7 days, with mean size change from 5.4 mm of high-risk nodules to 9.5 mm of hypervascular HCCs. CONCLUSION. Approximately one third of newly developed hypervascular HCCs had the presence of high-risk nodule before hypervascularization in the serial gadoxetic acid-enhanced MRI examinations. High-risk nodule tended to develop into hypervascular HCC after having almost doubled in size during 1 year of high-risk nodule presence.