Introduction: This study was carried out to investigate the global and regional morphometric and iron changes in grey matter (GM) of multiple sclerosis (MS) patients and link them to the white matter (WM) lesions in a multimodal magnetic resonance imaging approach.
Material and methods: The study involved 30 relapsing-remitting MS (RRMS) patients along with 30 age-matched healthy controls (HC) who were scanned on a 3T Siemens Trio system. The scanning protocol included a 3D, high resolution T1, T2, and T2*-weighted sequences. The T1-w images were used in FreeSurfer for cortical reconstruction and volumetric segmentation, while T2-w images were used to extract the WM T2 lesions; however, iron and magnetic susceptibility were calculated from the phase data of the T2*-w sequence. Surface-based analyses were performed in FreeSurfer to investigate the regional cortical morphometric changes and their correlations with the expanded disability status scale (EDSS), WM T2 lesions load, cortical iron deposition and magnetic susceptibility.
Results: Significant differences were detected between the RRMS patients and HC for all cortical and subcortical morphometric changes. The EDSS and T2 lesion load showed weak to moderate correlation with the reduced cortical morphometric measurements, increased cortical magnetic susceptibility and iron concentration. All deep grey matter (dGM) volumes showed a significant strong positive correlation with the cortical surface area and volume in RRMS patients and HC.
Conclusions: Grey matter is very much involved in the RRMS and cortical morphometric changes occur in a non-uniform pattern and are very likely to be associated with cortical iron deposition and magnetic susceptibility, dGM atrophy, WM T2 lesion load, and disability.
Keywords: Cortical grey matter; Iron; Lesion load; Magnetic susceptibility mapping; Relapsing-remitting multiple sclerosis.