Quantitative assessment of brain iron by R2* relaxometry in patients with clinically isolated syndrome and relapsing–remitting multiple sclerosis

Abstract

Background Increased iron deposition has been implicated in the pathophysiology of multiple sclerosis (MS), based on visual analysis of signal reduction on T2-weighted images. R2* relaxometry allows to assess brain iron accumulation quantitatively. Objective To investigate regional brain iron deposition in patients with a clinically isolated syndrome (CIS) or relapsing–remitting MS (RRMS) and its associations with demographical, clinical, and conventional magnetic resonance imaging (MRI) parameters. Methods We studied 69 patients (CIS, n = 32; RRMS, n = 37) with 3T MRI and analyzed regional R2* relaxation rates and their correlations with age, disease duration, disability, T2 lesion load, and normalized brain volumes. Results Basal ganglia R2* relaxation rates increased in parallel with age ( r = 0.3–0.6; P < 0.01) and were significantly higher in RRMS than in CIS ( P < 0.05). Using multivariate linear regression analysis, the rate of putaminal iron deposition was independently predicted by the patients’ age, disease duration, and gray matter atrophy. Conclusions Quantitative assessment by R2* relaxometry suggests increased iron deposition in the basal ganglia of MS patients, which is associated with disease duration and brain atrophy. This technique together with long-term follow-up thus appears suited to clarify whether regional iron accumulation contributes to MS morbidity or merely reflects an epiphenomenon.