MR imaging of hepatocellular carcinoma: usefulness of four-phase dynamic imaging including early arterial phase

To evaluate the usefulness of four-phase dynamic MR imaging technique by analyzing the imaging features of hepatocellular carcinoma(HCC). We reviewed four-phase dynamic MR images of 63 lesions in 38 patients. MR imaging of the whole liver on gradient T1-weighted sequence was obtained at 10 seconds(phase 1), 35 seconds(phase 2), 60 seconds(phase 3), and 5 minutes(phase 4) after the start of Gd-DTPA(0.1 mmol/kg) hand injection(3-4cc/sec) through the vein. We evaluated the degree of lesional contrast enhancement during each phase by comparing surrounding liver parenchyma, and analyzed signal intensity in lesions over and less than 2cm, respectively. The number of lesions showing high signal intensity compared with surrounding liver parenchyma was 52(83%) during phase 1, 30(48%) during phase 2, 12(19%) during phase 3, and 4(6%) during phase 4. During each phase, the number of lesions with signal intensity lower than that of surrounding liver parenchyma was 7(11%), 2(3%), 7(11%) and 21(33%), respectively. Thirty-four lesions were enhanced only during phase 1 and eleven during only phase 2. In tumors less than 2cm(n=40), more enhanced lesions were during phase 1(n=33) than more during phase 2(n=16)(p=0.0020). During each phase, four-phase dynamic MR imaging is useful for the effective detection of HCC showing varying degrees of contrast enhancement