Gadolinium dose optimisation in patients with multiple sclerosis: Intra- and inter-individual comparisons

Objective: To assess the efficacy of single, double and triple doses of 1 M gadolinium in the magnetic resonance (MR) evaluation of multiple sclerosis (MS) lesions in order to establish the best trade-off in terms of dose and number of injections. Materials and methods: Twenty-three patients with relapsing remitting or secondary progressive MS underwent MR scans of the brain, spine or both. Signal intensity, the number of enhancing lesions and the areas of MS plaque were measured in T1-weighted images before and after single, double or triple doses of contrast medium. Wilcoxon's two-sample test and the Mann-Whitney U-test were used to evaluate the differences between the groups, and between doses in the same patient. Results: There was no significant difference in area signal intensity or the number of enhancing lesions between the group examined after a single injection of double-dose (DD) contrast medium and the group examined after multiple injections of a triple dose (TD). The difference in the areas of enhancement and signal intensity between a single dose (SD) and TD significantly increased after the second bolus. Conclusion: Gadolinium injections in MS patients can be optimised by giving a single DD bolus, which leads to the same results as a TD administered as two boli.