Our study shows that the increase in the unenhanced T1 signal intensity has a linear relationship with the eMRIn in patients with MS and BM. Indeed, we estimated a linear regression model to fit the progressive increase in T1 signal intensity of the dentate nucleus after multiple enhanced MRI scans. This finding suggests substantial dechelation of gadodiamide in patients with normal renal function, raising further concerns regarding the stability of this agent. Further comparative studies with other gadolinium chelates, specifically both linear and macrocyclic, are strongly recommended.

The dentate nucleus of the cerebellum may appear as hyperintense on unenhanced T1 magnetic resonance images (MRIs) of the brain. Recently, T1 signal hyperintensity has received attention owing to data on the association of this finding with the history of multiple injections of gadolinium-based contrast agents, specifically gadodiamide, in patients with multiple sclerosis and brain metastases. We conducted a retrospective study on patients with a meningioma who had routinely undergone follow-up enhanced MRI scans with gadodiamide. Across a time interval of 18 months (from January 2013 to July 2014), we identified 102 consecutive patients eligible for this study. A significant increase in T1 hyperintensity of the dentate nuclei of the cerebellum on nonenhanced scans was observed between the first and the last MRI in the group of patients with a history of at least 6 enhanced MRI scans (P < 0.01), whereas no differences were observed in the group with 1 to 5 enhanced MRI scans (P = 0.74). Further research is necessary to shed light on the mechanism of the T1 hyperintensity as well as on the histological and microstructural appearance of the dentate nucleus after multiple intravenous injections of gadodiamide. The finding raises the question of substantial dechelation of this agent in patients with normal renal function.

Background The dentate nuclei of the cerebellum are the areas where gadolinium predominantly accumulates. It is not yet known whether gadolinium deposition affects brain functions. Purpose/Hypothesis To assess whether gadolinium‐dependent high signal intensity of the cerebellum on T1‐weighted images of nonneurological adult patients with Crohn's disease is associated with modifications of resting‐state functional connectivity (RSFC) of the cerebellum and dentate nucleus. Study Type Observational, cross‐sectional. Population Fifteen patients affected by Crohn's disease were compared with 16 healthy age‐ and gender‐matched control subjects. All participants underwent neurological, neurocognitive‐psychological assessment, and blood sampling. Field Strength/Sequence 1.5‐T magnet blood oxygenation level‐dependent (BOLD) functional MRI. Assessment High signal intensity on T1‐weighted images, cerebellum functional connectivity, neurocognitive performance, and blood circulating gadolinium levels. Statistical Tests An unpaired two‐sample t‐test (age and sex were nuisance variables) was used to investigate between‐group differences in cerebellar and dentate nucleus functional connectivity. Z‐statistical images were set using clusters determined by Z > 2.3 and a familywise error (FWE)‐corrected cluster significance threshold of P = 0.05. Results Dentate nuclei RSFC was not different (P = n.s.) between patients with gadolinium‐dependent high signal intensity on T1‐weighted images and controls. Pre‐ and postcentral gyrus bilaterally and the right supplementary motor cortex showed a decrease of RSFC with the cerebellum hemispheres (P < 0.05 FWE‐corrected) and was related to disease duration but not to gadodiamide cumulative doses (P = n.s.). Data Conclusion Crohn's disease patients with gadolinium‐dependent hyperintense dentate nuclei on unenhanced T1‐weighted images do not show dentate nucleus RSFC changes. Level of Evidence: 2 Technical Efficacy Stage: 5 J. Magn. Reson. Imaging 2019;50:445–455.

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