The clinical outcome of small (<20 mm) arterially enhancing nodules on MRI in the cirrhotic liver

OBJECTIVES: To evaluate the outcome of arterially enhancing nodules (AENs) measuring <20 mm detected on MRI in patients with cirrhosis. METHODS: Prospective analysis of 54 patients with a total of 161 AENs <20 mm on MRI. Inclusion criteria included a minimum of 12 months of MRI follow-up or histological evaluation of the AEN. Key exclusions were patients with an AEN >20 mm or prior diagnosis of HCC. Two radiologists blinded to the clinical and pathological data reviewed serial MRIs and classified the AENs as no longer visible, stable, increasing, or decreasing in size. RESULTS: A total of 161 AENs were identified and were followed by serial MRI for a mean of 24 months. Eighty (50%) AENs were no longer visible on repeat imaging, 42 (26%) remained stable, 1 of which was diagnosed as HCC on short-term follow-up, 8 (5%) increased in size and were subsequently diagnosed as HCC, and 24 (15%) decreased in size. In addition, 7 AENs (4%) were diagnosed on biopsy immediately following the initial MRI. Overall MR characteristics diagnostic of HCC were growth > or =2 mm and peripheral rim enhancement on initial MRI. CONCLUSIONS: The majority (90%) of AENs <20 mm in cirrhosis are benign. The presence of rim enhancement or interval growth of an AEN are suggestive of HCC.