Outcomes of follow-up CT for small (5-10-mm) arterially enhancing nodules in the liver and risk factors for developing hepatocellular carcinoma in a surveillance population

Objective:: To evaluate the outcomes of small (5-10 mm), arterially enhancing nodules (SAENs) shown exclusively at the hepatic arterial phase of CT in a hepatocellular carcinoma (HCC) surveillance population and to determine risk factors for developing HCC. Methods:: The study population included 112 patients (male:female=100:12; aged 36-92 years) with 175 SAENs who were at risk of HCC. We evaluated serial changes during follow-up (1.4-41.8 months, mean 35.7 months) and analysed the initial CT findings of SAENs and the accompanying lesions to elucidate the risk factors for HCC development. Results:: Of 175 SAENs, 101(57.7%) disappeared and 34(19.4%) persisted. Forty SAENs (22.9%) became HCC in 33 patients (29.5%). Presence of HCC treatment history (p=0.005, risk ratio=7.429), a larger size of SAEN (p=0.003, risk ratio=1.630), presence of coexistent HCC (p=0.021, risk ratio=3.777) and absence of coexistent typical arterioportal shunts (p=0.003, risk ratio=4.459) turned out to be independently significant risk factors for future development of HCC. Conclusion:: SAENs were frequently seen in an HCC surveillance population and have a 22.9% probability of becoming HCC on a per-lesion basis. Risk increased particularly when the lesion was associated with a previous or concurrent HCC, a large size or found without a coexistent typical arterioportal shunt.