Objective: To determine the outcome of small arterial phase-enhancing nodules, 10-20 mm, seen on serial triphasic liver CT scans in a hepatocellular cancer-screening population.
Methods: Of 58 patients referred for triphasic liver CT, 20 (18 men, 2 women) with 32 nodules formed the study group. Each patient in the study group had at least two CT scans, a minimum of 3 months follow-up, at least one nodule measuring 10-20 mm, no prior diagnosis of hepatocellular carcinoma, and no nodule greater than 20 mm typical of hepatocellular carcinoma at the time of the first CT. Serial CT scans were reviewed by an abdominal imaging radiologist who classified the nodules as stable, decreasing, or increasing in size.
Results: A mean of six CT studies (range 2-10) were performed for each patient with a mean follow-up of 25 months (range 4-47 months). Of 32 nodules, 14 (44%) were stable, 9 (28%) decreased, and 9 (28%) increased in size. Nodules that increased in size were treated as hepatocellular carcinoma: six were hepatocellular carcinoma, two were biopsy negative but showed recurrent tumor after radiofrequency ablation, and one was a high-grade dysplastic nodule. Mean doubling time for these nine nodules was 5.7 months (range 2.3-10.8 months).
Conclusions: Most small (10-20 mm) arterial phase-enhancing nodules seen on triphasic liver CT are not hepatocellular carcinoma. Serial CT is useful to guide management in these patients. Growth of small arterial phase-enhancing nodules can be used as an indicator that the nodule should be treated as hepatocellular carcinoma.