A double-blind study to evaluate the efficacy and tolerability of a higher dose (0.3 mmol per kg bw) of gadodiamide injection as a contrast medium for MRI

Gadodiamide injection was administered intravenously to 48 patients with known or suspected central nervous system (CNS) lesions undergoing magnetic resonance imaging (MRI). Two parallel groups were examined to evaluate the efficacy and safety of single doses of 0.1 and 0.3mmol per kg bw. The principal measures of efficacy were diagnostic yield of MR images, the overall contrast enhancement and the contrast index (CI). Adverse events and serum bilirubin level were the main safety parameters. Nineteen patients in each dose group displayed contrast enhancement of the MR image (1.5 T Siemens Gyroscan MR unit;T ₁ TR/TE=560–650/15–25 ms;T ₂:TR/TE=2200–3100/22–90 ms). The CI increased by 47.3% in the 0.1 mmol/kg bw group and by 86.5% in the 0.3 mmol per kg bw group compared to the pre-contrast scan. Four patients in the 0.1 mmol per kg bw group and seven in the 0.3 mmol per kg bw group had their management changed by new information from the post-contrast scan and four patients in each dose group had their diagnosis altered following the post-contrast scan. Two patients in the 0.3 mmol per kg bw group experienced injection-associated discomfort. There were no other adverse events reported during the 24 h follow-up period. No clinically significant changes in serum bilirubin or other parameters of blood chemistry or haematology were observed. The study demonstrates that the safety profile of gadodiamide injection 0.3 mmol per kg bw is similar to that of 0.1 mmol per kg bw and that, at both doses, gadodiamide injection is a safe and effective contrast medium for use in patients undergoing MRI on the CNS. Slightly more patients had an improvement in diagnostic yield with the 0.3 mmol per kg bw dose and the CI was increased to a greater extent in this group, showing that when greater contrast is required the higher dose of gadodiamide injection may be considered. Further studies in selected patient groups, and with the use of different doses in the same patient are necessary to evaluate the diagnostic value of higher doses.