[Follow-up dynamic CT study for hypovascular nodules in patients with cirrhotic liver].

It is important to clarify the process by which hypovascular nodules progress to hypervascular hepatocellular carcinoma (HCC). In this study, we used dynamic computed tomography(CT) to retrospectively investigate serial changes in 24 hypovascular nodules of 24 patients until they progressed to hypervascular HCC. The mean time to hypervascular transformation(THT) was 726 days, with a minimum of 208 days and maximum of 2,728 days. Mean nodular diameter at the final examination was 21.2 +/- 8.0 mm, and was significantly larger than that(11.4 +/- 4.8 mm) at the initial time. THT was the shortest(463 days) in a group that had an initial nodular diameter larger than 15 mm. In a group with the low-iso-low contrast enhancement pattern, THT was 361 days, and was shorter than that in the other groups. In a group with the low-low-low contrast enhancement pattern, nodules containing fat were frequently detected(5 patients, 75%). In patients with HCC apart from the nodules, THT for the nodules was 464 days, shorter than that(767.5 days) in other patients. The findings suggest that hypovascular nodules larger than 15 mm in diameter with the low-iso-low contrast enhancement pattern and HCC progress to hypervascular HCC at an early stage.