Quantitative high-field imaging of sub-cortical gray matter in multiple sclerosis

Background: In addition to neuronal injury, inflammatory, and demyelinating processes, evidence suggests multiple sclerosis (MS) is also associated with increased iron deposition in the basal ganglia. Magnetic resonance imaging (MRI), particularly at very high field strengths, is sensitive to iron accumulation and may enable visualization and quantification of iron associated with MS. Objectives: To investigate the sub-cortical gray matter in patients with early-stage relapsing-remitting MS using multiple, and novel, quantitative MRI measures at very high field. Methods: In total, 22 patients with relapsing-remitting MS and 22 control subjects were imaged at 4.7 Tesla. Transverse relaxation rates (R-2 and R-2*) and susceptibility phase were quantified in four basal ganglia nuclei, the thalamus, and the red nuclei. Parameters in patients with MS were compared with those in healthy subjects and correlated with clinical scores. Results: Significant abnormalities were observed in most structures, most notably in the pulvinar sub-nucleus. Significant correlations with disability were observed in the pulvinar; marginally significant correlations were also observed in the thalamus and red nucleus. No significant correlations were observed with duration since index relapse. Conclusions: Widespread abnormalities are present in the deep gray matter nuclei of patients recently diagnosed with MS; these abnormalities can be detected via multi-modal high-field MRI. Imaging metrics, particularly R-2*, relate to disease severity in the pulvinar and other gray matter regions.