Intra-individual, randomised comparison of the MRI contrast agents gadobutrol and gadoterate in imaging the distal lower limb of patients with known or suspected osteomyelitis, evaluated in an off-site blinded read.

OBJECTIVE: To prove that 1.0 M gadobutrol provides superior contrast enhancement in suspicion of osteomyelitis of the feet compared with 0.5 M gadoterate. METHODS: MRI of feet was performed on 2 separate occasions. Independent injections of 1.0 M gadobutrol and 0.5 M gadoterate at doses of 0.1 mmol Gd/kg body weight were administered per patient. The interval between the two MR examinations was between 24 h and 7 days. Evaluation was performed in an off-site blinded read. RESULTS: 41 patients were eligible for efficacy analysis. Results of secondary efficacy variables did not show statistically significant differences. For the primary efficacy variable, a trend in favour of gadobutrol was seen in the full analysis set (ITT) population resulting in at least non-inferiority. In the per protocol (PP) analysis set gadobutrol had better contrast than gadoterate (Wilcoxon signed rank test, p = 0.0466). CONCLUSION: Imaging of the distal lower limb in this special patient population requires a large number of patients to obtain enough comparative images where non-contrast-agent-dependent factors do not disturb contrast agent efficacy. The ITT analysis showed at least non-inferiority of gadobutrol in comparison to gadoterate. The avoidance of imaging artefacts demonstrates a better outcome for gadobutrol.