The role of 7 T MRI to assess atrophy of the subcortical deep gray matter in relapsing–remitting multiple sclerosis

Deep gray matter (DGM) atrophy and lesions are found in multiple sclerosis (MS).

To optimize automated segmentation for 7 T DGM volumetrics and assess sensitivity to atrophy and relationship to DGM lesions and disability in relapsing–remitting (RR) MS.

30 RRMS subjects [mean age 44.0 years, median Expanded Disability Status Scale (EDSS) score 2] and 14 healthy controls underwent 7 T MRI with 3D magnetization-prepared 2 rapid gradient-echoes (MP2RAGE) and fluid-attenuated inversion recovery. Customizing an automated pipeline to assess DGM structure volumes required pre-processing combining two MP2RAGE inversion times and uniform T1 images, and noise-suppressed reconstruction. DGM volumes were normalized. Brain DGM lesions and white matter T2 lesion volume (T2LV) were expert-quantified. Spearman correlations and Wilcoxon rank-sum tests were assessed.

DGM lesions were found in 77% (n = 23) of MS subjects and no controls, with thalamic lesions most prevalent (73%). An average of 3.6 DGM lesions was found per person with MS. Total DGM volumes were lower in MS vs. controls (p = 0.034), varying by region, most pronounced in the caudate (p = 0.008). DGM volumes inversely correlated with EDSS (total DGM: r = – 0.45, p = 0.014; globus pallidus: r =  – 0.42, p = 0.023; putamen: r = – 0.44, p = 0.016; caudate: r = – 0.37, p = 0.047) and T2LV (total DGM: r = – 0.53, p = 0.003; putamen: r = – 0.40, p = 0.030; thalamus: r = – 0.63, p < 0.001). DGM atrophy was most closely linked to disability among all MRI measures. Thalamic lesion volume correlated inversely with thalamic volume (r = – 0.38, p = 0.045).

7 T MRI shows a link between DGM atrophy and both white matter lesions and physical disability in RRMS. Thalamic lesions are associated with thalamic atrophy.