PURPOSE: To compare liver hemangioma with hepatocellular carcinoma (HCC), as seen on superparamagneticiron oxide (SPIO)-enhanced MR images. MATERIALS AND METHODS: The study involved 30 patients with 51 focal hepatic mass lesions (31 hemangiomas, 20 HCCs). Breath-hold T1-weighted fast low angle shot (FLASH) and respiratory-triggered T2-weighted turbo-spin echo (TSE) images were obtained at 1.5 T before and after intravenous administration of SPIO particles. For quantitative analysis, percentage signal intensity change (PSIC) and contrast-to-noise ratio (CNR) of the lesions were calculated for T1-weighted FLASH and T2-weighted TSE before and after intravenous administration of SPIO particles. In addition, lesion conspicuity and imaging artifacts were analyzed qualitatively. RESULTS: After SPIO administration, percentage signal intensity increase on T1-weighted FLASH images was 73.0 +/-22.1% for hemangiomas and 21.8 +/-12.6% for HCCs, the difference being significant (p < 0.05). Taking a signal increase of 40% on postcontrast T1-weighted FLASH as the cut-off value, sensitivity and specificity for hemangiomas were 96.8% and 100%, respectively. In addition, the percentages of signal intensity loss on T2-weighted TSE images for hemangiomas and HCCs were 35.5 +/-17.2% and 0.2 +/-10.5%, respectively (p < 0.05). A comparison of lesion to liver CNR before and after SPIO infusion showed readings-for hemangiomas and HCCs, respectively - of 15.4 +/-6.0 and 4.7 +/-4.4 on T1-weighted FLASH images, and -2.6 +/-0.7 and 2.7 +/-4.4 on T2-weighted TSE images (p < 0.05). Qualitative analysis indicated that the conspicuity of HCCs was noticeably greater on postcontrast T2-weighted TSE images than on precontrast images (p < 0.05). CONCLUSION: The positive enhancement seen on T1-weighted FLASH images and the negative enhancement on T2 weighted TSE observed in liver hemangiomas after the administration of SPIO particles are valuable diagnostic features that can help characterize hemangiomas and differentiate them from HCCs.