DETECTION AND CHARACTERIZATION OF PRIMARY LIVER-CANCER IN RATS BY MS-264-ENHANCED MRI

A new MR contrast agent, MS-264 (Gd(1RS)-1-(p-butylbenzyl)-DTPA), was developed to achieve hepatobiliary specificity and its potential evalu ated for detecting and characterizing liver tumors in rats with chemic ally induced hepatocellular carcinoma (HCC). In seven rats with 66 HOC lesions, enhancements of different abdominal organs and tumors were c ompared on T-1-weighted images after intravenous administration of Gd- DTPA (0.3 mmol/kg) and MS-264 (0.05 mmol/kg). MR images were correlate d with postmortem microangiographic and histological findings. An over all enhancement of different organs, which normalized within 24 h, was observed after Gd-DTPA and MS-264 injection. MS-264 caused a higher r elative enhancement (RE) in liver (60%), compared with that of Gd-DTPA (40%), which resulted in a prompt negative contrast enhancement in 59 of 66 HCCs. All were moderately to poorly differentiated (Grades II-I V) tumors. Six of these 59 negative contrast-enhancing lesions showed a positively enhanced peritumoral rim, which corresponded histological ly to malignant infiltration (n = 2) or compression (n = 4), On the ot her hand, six well differentiated HCCs showed prolonged positive enhan cement. However, one well differentiated HCC was not positively enhanc ed by MS-264, probably due to poor access of the agent to the lesion. In comparison to that of the precontrast images, enhancement with Gd-D TPA and MS-264 increased the number of detected lesions by 22 and 42%, respectively. In this animal study, MS-264 proved to be useful in det ection and characterization of primary liver cancers.