Introduction: MS demyelination and atrophy alter the tissue's diamagnetic properties leading to higher tissue magnetic susceptibility1. High levels of iron accumulation have been detected in the deep grey matter (DGM) structures of people with MS (pwMS)1. Quantitative susceptibility mapping (QSM) is a novel post-processing imaging modality that quantifies tissue magnetic susceptibility using a gradient-recalled-echo (GRE) sequence.
Objective: To characterise the magnetic susceptibility in selected DGM structures with reference to medial-frontal white matter for pwMS and healthy controls (HC). Correlation between DGM QSM metrics and selected MS clinical parameters were computed.
Method: Five relapsing-remitting multiple sclerosis (RRMS) participants and nine age-matched HC were recruited (mean age: 46±14 yrs). MRI scans were performed on a 3T scanner. The STI Suite (v2.2) was used for QSM map reconstruction from 3D GRE images. The significant QSM differences associated with selected DGM structures were assessed using repeated-measures ANOVA controlling for the reference region. RRMS clinical measures included disease duration, cognitive, fatigue, mental health assessment as well as Expanded Disability Status Scale. Correlations between clinical measurement scores and iron-rich regions, accounting for age, were performed using Pearson’s correlation.
Result: The RRMS participants showed significantly higher susceptibility compared to HCs in the caudate (β= +26.2, p = 0.004), pallidum (β= +38.9, p = 0.006) with a trend toward significant for putamen (β= +21.2, p = 0.09), and significantly lower susceptibility in thalamus (β= –10.2, p = 0.04). For RRMS cohort, pallidum and thalamus QSM values were highly correlated with the anxiety scale (r=0.98, r=-0.93, respectively). The dentate nucleus and putamen were highly correlated with the disease duration (r=-0.93, r=-0.91, respectively) with p<0.05.
Conclusion: These preliminary QSM results from pwMS suggest that neurodegenerative and neuroinflammatory processes in DGM (caudate, pallidum, putamen, thalamus, dentate nucleus) might lead to clinical symptoms. While the studied cohorts were small, our research supports the promising nature of QSM to investigate the contribution of iron in the pathophysiology of MS.