Evaluation of Gadodiamide Versus Gadobutrol for Contrast-Enhanced MR Imaging in a Rat Brain Glioma Model at 1.5 and 3 T

Purpose: To compare equivalently-dosed (0.1 mmol/kg) gadobutrol (Gadovist) and gadodiamide (Omniscan) in a rat brain glioma model with respect to lesion signal-to-noise (SNR), contrast-to-noise (CNR), and contrast enhancement (CE) at 1.5 and 3 T. Lesion enhancement with standard-dose gadobutrol in scans performed at 1.5 T was also compared with that of half-dose gadobutrol in scans performed at 3 T. Materials and Methods: Fifty-four rats were injected with glioma cells via a plastic brain cannula and divided into 3 groups. In the first group, each animal was studied using gadodiamide and gadobutrol, with 24 hours separating injections. The 2 agents were administered in random order at a dose of 0.1 mmol/kg. Each animal was scanned using a 3 T MR system. The procedure for the second group was similar, but scanning was performed at 1.5 T. For the third group, rats were given standard or half-dose gadobutrol and scanned at 1.5 and 3 T, respectively. For all MR examinations, T1-weighted images were obtained precontrast and at 1, 3, 5, 7, and 9 minutes postcontrast administration. Results: At 3 T improvements in SNR, CNR, and CE with gadobutrol ranged from 11.8% to 16.0%, 30.5% to 35.4%, and 27.1% to 31.5%, respectively, and at 1.5 T from 7.0% to 11.1%, 27.1% to 35.8%, and 23.8% to 29.5%, respectively. Differences between these parameters with gadobutrol and gadodiamide were statistically significant (P < 0.0001-0.05) at all time points following contrast administration. In group 3, no significant differences in CNR or CE were found between full dose gadobutrol at 1.5 T and half-dose at 3 T, although SNR was significantly greater (28.5%-35.1%; P < 0.0008) at 3 T. Conclusion: Gadobutrol (Gadovist) demonstrates superior lesion enhancement to equivalently-dosed gadodiamide (Omniscan) in the rat brain glioma model. These results are complemented by the improved observed and theoretical safety profile of the first agent, in particular with regard to nephrogenic systemic fibrosis. The ability to image with half-dose gadobutrol at 3 T without a statistically significant decrease in lesion enhancement, compared with 1.5 T, offers an additional theoretical safety margin and potential cost-savings.