PURPOSE: To evaluate intrahepatic nodular lesions detected on CTAP but not on conventional contrast CT in regard to its relationship with satellite nodules or borderline malignancies. MATERIALS AND METHODS: From June 1991 to March 1994, CTAP was undertaken in 132 cases with confirmed hepatocellular carcinoma(HCC), of which 35 cases having 82 lesions were suitable for analysis(excluding the cases which had no follow-up studies, showed segmental abnormal portal perfusion, no additional lesions and, or inumerable lesions). The CTAP findings were compared with those on artery dominant imaging studies (angiography, DSA, bolus dynamic CT, arterial CT, Lipiodol CT) taken during the same period(to confirm the presence of lesions) and the findings on follow-up imaging studies(to assess the developemerit of malignancy). RESULTS: Arterial vascularity was identified in 35 of 82 lesions(42.7%) on arterial dominant imaging studies. Developement into malignancy was identified on follow-up imaging studies in 25 of remained 47 lesions(53.2%). CONCLUSION: The total positive predictive value of nodules on CTAP was 73.2%(35+25/82), but the predictive value for HCC by follow-up only was 53.2%. Given'the difficulties in detecting intranodular arterial flow and the short follow-up duration in many patients, the actual positive value might be higher.