Brain relaxometry after macrocyclic Gd-based contrast agent.

PURPOSE: To assess if ratios of T1-weighted (T1w) signal intensity (SI) and quantitative T1 relaxometry (qT1) change on serial administration of macrocyclic gadobutrol.

METHODS: A total of 17 glioblastoma patients were scanned at 3.0 T magnetic resonance imaging (MRI) every 6 weeks after tumor resection with standard MRI and T1 and T2 relaxometry before and after gadobutrol administration. On co-registered images T1w SI was measured and relaxation times T1 (qT1) and quantitative T2 (qT2) were quantified in several deep grey matter nuclei as ratios relative to frontal white matter and to the pons. Ratio changes were evaluated over time with a paired t‑test and multiple regression.

RESULTS: An average of 8 (range 5-14) scans per patient were completed. Ratios of T1w SI, qT1 and qT2 remained unchanged for all target regions from the first to the last time point (p > 0.05) and did not correlate with the number of gadobutrol administrations. Multivariate regression showed no significant impact of gadobutrol on qT1 or qT2 ratios, but a significant negative effect on T1w SI ratios. Gender also had no impact on the ratios but age had a significant negative influence on the qT1 ratio.

CONCLUSION: Multiple administrations of a macrocyclic contrast agent did not change relaxation time T1 ratios in any deep grey matter structure.