Comparative evaluation of lesion enhancement using 1 M gadobutrol vs. 2 conventional gadolinium chelates, all at a dose of 0.1 mmol/kg, in a rat brain tumor model at 3 T.

Purpose: The purpose of this study is to compare the differences in contrast enhancement using 0.1 mmol/kg body weight 1 M gadobutrol versus 2 standard gadolinium chelates, both formulated at 0.5 M, (gadopentetate dimeglumine and gadoterate meglumine) in a standardized rat brain glioma model at 3 T.

Materials And Methods: A total of 19 rats were evaluated, divided into 2 groups. Group 1 (n = 10) was examined using gadobutrol and gadopentetate dimeglumine and group 2 (n = 9) was examined using gadobutrol and gadoterate meglumine. The time between the intraindividual injections was at least 24 hours and contrast agent injections were performed in a randomized order. All agents were applied at a dose of 0.1 mmol/kg body weight.Image acquisition was performed using a T1-weighted 2D TSE technique (repetition time/echo time (TE) 500/16, FA 180 degrees) with an acquisition time of 1:47 minutes:seconds. At a field-of-view of 75 x 75 mm2 and a matrix size of 320 x 320, a voxel size of 0.2 x 0.2 x 2.0 mm3 was achieved. Data acquisition was performed before and at 5 consecutive time points every 2 minutes after contrast agent injection. Signal-to-noise ratios (SNRs) of tumor and normal contralateral brain as well as contrast-to-noise ratio (CNR) measurements were performed using region of interest analysis.

Results: The increase in tumor contrast enhancement, ranged between 19.6% and 35.9% for gadobutrol versus gadopentetate dimeglumine (group 1) and between 23.2% and 27.8% for gadobutrol versus gadoterate meglumine (group 2). Overall, CNR was statistically significantly higher for gadobutrol in both groups (P < 0.0001). CNR values for gadobutrol were 25.5 +/- 8.2 in group 1 and 27.1 +/- 8.3 in group 2 with respective CNR values for gadopentetate dimeglumine of 18.6 +/- 5.6 and gadoterate meglumine of 19.2 +/- 5.3. At each acquired time point mean values of tumor SNR were higher for gadobutrol (group 1: SNR(mean) range from 78.7-89.1 vs. 74.3-80.8; group 2: SNR(mean) range from 79.9-88.9 vs. 74.2-80.8). Tumor SNR was statistically significant different at all measured time points in group 2 (P < 0.05). In group 1, the difference of tumor SNR was also statistically significant for the gadobutrol/gadopentetate dimeglumine comparison (P < 0.05) with exception of time point at 9 minutes postcontrast (P = 0.07).

Conclusion: The results of this study show significantly higher brain tumor SNR and CNR postcontrast for gadobutrol compared with gadopentetate dimeglumine and gadoterate meglumine at 3 T. Injecting the same gadolinium chelate dose on a weight basis, tumor mean SNR gains were superior for gadobutrol at all acquired postcontrast time points. This result with gadobutrol may facilitate better brain tumor detection in the presence of blood-brain barrier disruption.