In vivo dentate nucleus MRI relaxometry correlates with previous administration of Gadolinium-based contrast agents

Objectives: To evaluate changes in T1 and T2* relaxometry of dentate nuclei (DN) with respect to the number of previous administrations of Gadolinium-based contrast agents (GBCA). Methods: In 74 relapsing-remitting multiple sclerosis (RR-MS) patients with variable disease duration (9.8±6.8 years) and severity (Expanded Disability Status Scale scores:3.1±0.9), the DN R1 (1/T1) and R2* (1/T2*) relaxation rates were measured using two unenhanced 3D Dual-Echo spoiled Gradient-Echo sequences with different flip angles. Correlations of the number of previous GBCA administrations with DN R1 and R2* relaxation rates were tested, including gender and age effect, in a multivariate regression analysis. Results: The DN R1 (normalized by brainstem) significantly correlated with the number of GBCA administrations (p<0.001), maintaining the same significance even when including MS-related factors. Instead, the DN R2* values correlated only with age (p=0.003), and not with GBCA administrations (p=0.67). In a subgroup of 35 patients for whom the administered GBCA subtype was known, the effect of GBCA on DN R1 appeared mainly related to linear GBCA. Conclusions: In RR-MS patients, the number of previous GBCA administrations correlates with R1 relaxation rates of DN, while R2* values remain unaffected, suggesting that T1-shortening in these patients is related to the amount of Gadolinium given. Key Points: o In multiple sclerosis, previous Gadolinium administrations correlate with dentate nuclei T1 relaxometry. o Such correlation is linked to linear Gadolinium chelates and unrelated to disease duration or severity. o Dentate nuclei T2* relaxometry is age-related and independent of previous Gadolinium administrations. o Changes in dentate nuclei T1 relaxometry are not determined by iron accumulation. o MR relaxometry can quantitatively assess Gadolinium accumulation in dentate nuclei.