PURPOSE: The purpose of this study was to evaluate enhancement patterns, as seen on two-phase spiral CT, of hepatic hemangiomas in which atypical features had been seen on sonography (US) MATERIALS AND METHODS: Two-phase spiral CT scanning was performed in 18 patients in whom 24 atypical hemangiomas had been seen on US. Two-phase images were obtained at 25-45 seconds (arterial dominant phase) and 2-5 minutes (equilibrium phase) after the initiation of a bolus injection of contrast material (150 ml, 5 ml/sec). Enhancement patterns of hemangiomas during each phase were classified as homogeneous high, peripheral high, or low attenuation, and were retrospectively analyzed. RESULTS: In the arterial dominant phase of spiral CT, low attenuation was seen in nine hemangiomas (38%), globular or spotty peripheral high attenuation in 14 (58%), and homogeneous high attenuation in one (4%). In the equilibrium phase, enhancement patterns were peripheral high attenuation (partial fill-in) in 18 lesions (75%), and homogeneous high attenuation (complete fill-in) in three (12.5%), In the other three (12.5%) enhancement showed no significant change; in one of these, density was slightly less than in the arterial phase, and two showed subtle peripheral high attenuation. Fourteen hemangiomas (58%) showed globular or spotty peripheral high attenuation in the arterial dominant phase and peripheral or homogeneous high attenuation with progressive centripetal enhancement in the equilibrium phase. CONCLUSION: Our results suggest that two-phase spiral CT during the arterial dominant and equilibrium phase is useful in differentiating hepatic hemangiomas with atypical features seen on US from malignant hepatic tumors.