T1 Signal-Intensity Increase in the Dentate Nucleus after Multiple Exposures to Gadodiamide: Intraindividual Comparison between 2 Commonly Used Sequences.

BACKGROUND AND PURPOSE: Different T1-weighted sequences have been used for qualitative and quantitative evaluation of T1 signal intensity related to gadolinium deposition in the dentate nucleus in patients who underwent several enhanced MR imaging studies. Our purpose was to perform an intraindividual qualitative and quantitative comparison between T1-weighted spin-echo and 3D magnetization-prepared rapid acquisition of gradient echo sequences in patients who had multiple exposures to gadodiamide. MATERIALS AND METHODS: Our retrospectively selected population included 18 patients who underwent at least 3 administrations of gadodiamide and had a baseline and a final MR imaging performed with both T1-weighted sequences. Qualitative and quantitative analyses were independently performed. Dentate nucleus/middle cerebellar peduncle signal-intensity ratios and signal changes between the baseline and final examinations were compared by using the Wilcoxon signed rank test. Correlation between quantitative and qualitative evaluations was assessed by using a polyserial correlation test. RESULTS: The differences between the 2 sequences for both baseline and last examination dentate nucleus/middle cerebellar peduncle ratios were statistically significant (P = .008 and P = .006, respectively); however, the signal-intensity changes of the ratios with time were not (P = .64). The correlation between the qualitative and quantitative analysis was very strong (near-perfect) (r = 0.9) for MPRAGE and strong (r = 0.63) for spin-echo sequences. CONCLUSIONS: T1-weighted spin-echo and MPRAGE sequences cannot be used interchangeably for qualitative or quantitative analysis of signal intensity in the dentate nucleus in patients who received gadodiamide. Baseline and final examination ratios should be evaluated across time by using the same sequence. Qualitative analysis performed with MPRAGE correlated better with quantitative analysis and may offer advantages over spin-echo sequences for research purposes.

Gadolinium-Based Contrast Agent Accumulation and Toxicity: An Update.

In current practice, gadolinium-based contrast agents have been considered safe when used at clinically recommended doses in patients without severe renal insufficiency. The causal relationship between gadolinium-based contrast agents and nephrogenic systemic fibrosis in patients with renal insufficiency resulted in new policies regarding the administration of these agents. After an effective screening of patients with renal disease by performing either unenhanced or reduced-dose-enhanced studies in these patients and by using the most stable contrast agents, nephrogenic systemic fibrosis has been largely eliminated since 2009. Evidence of in vivo gadolinium deposition in bone tissue in patients with normal renal function is well-established, but recent literature showing that gadolinium might also deposit in the brain in patients with intact blood-brain barriers caught many individuals in the imaging community by surprise. The purpose of this review was to summarize the literature on gadolinium-based contrast agents, tying together information on agent stability and animal and human studies, and to emphasize that low-stability agents are the ones most often associated with brain deposition.