Enhancement patterns of small hepatocellular carcinoma shown by dynamic MRI and CT.

To study prospectively the enhancement features of small hepatocellular carcinoma (SHCC) with multi-phase scanning of dynamic MRI and spiral CT, and discuss the superiority of dynamic MRI to spiral CT.Multi-phase dynamic contrast scanning of high field MRI and spiral CT were performed in 53 patients with SHCC. The arterial phase, portal venous phase and delayed phase scanning of spiral CT was done after the pre-contrast scanning of the entire liver. MRI was performed with SE sequence and fast multiplanar spoiled gradient-recalled sequence dynamic multi-phase contrast scanning.Seventy-six lesions were found in all 53 patients. Sixty-nine and 54 of the 76 lesions enhanced obviously in MRI and spiral CT arterial phase scanning respectively. The typical enhancement patterns of SHCC in the arterial phase, portal venous phase and delayed phase scanning of MRI and spiral CT were hyper-hypo-hypointense (dense) and hyper-iso-hypointense (dense). Atypical enhancement patterns were hyper-hyper-hyperintense (dense), hyper-iso-isointense (dense) and hypo-hypo-hypointense (dense).Both MRI and spiral CT multi-phase dynamic contrast-enhanced scanning could demonstrate the enhancement features of SHCC, and arterial phase scan of MRI was superior to spiral CT in reflecting the hypervascular characterization of SHCC. In addition, MRI was better than spiral CT in characterization of hepatic lesions combined with SE sequence.