Time-course changes of contrast enhancement in iron colloid enhanced MRI in patients with hepatocellular carcinoma.

Time-course changes in contrast enhancement of chondroitin sulphate iron colloid (CSIC), an MR contrast agent, were determined in 12 patients with 20 lesions of classical hepatocellular carcinoma (HCC). Spin echo T1 weighted (T1WI) and T2 weighted images (T2WI) were obtained before administration of CSIC and 1, 6 and 24 h after injection. The signal-to-noise ratio (SNR) in the tumour region and the liver and the tumour-to-liver contrast-to-noise ratio (CNR) were calculated, and time-course changes of these ratios were determined. SNRs for tumour before the administration of contrast medium did not differ significantly from SNRs after administration on T1WI or T2WI. SNRs for the liver on both T1WI and T2WI were significantly lower at each time point after administration than before administration. The tumour-to-liver CNRs for both T1WI and T2WI were significantly higher after administration than before administration. The maximum CNR was observed 6 h after administration on both T1WI and T2WI. The contrast enhancement was maintained for at least 24 h, with a peak at 6 h after administration. The prolonged enhancement obtained with CSIC has extended the time during which effective contrast is maintained.