Researchers found significant differences between clinically relevant areas in participants with progressive MS, relapsing MS, and healthy controls.
Data from a recent study published in Multiple Sclerosis Journal suggest that myelin cervical cord abnormalities are related to clinical disability in multiple sclerosis (MS) and myelin water imaging (MWI) can be useful in monitoring subclinical disease progression.
Researchers found that myelin heterogeneity index (MHI) was higher by 9.5% to 31% in various regions of the cervical cord in people with progressive MS (PMS) compared to those without (P ≤.04), and higher by 13% to 26% in people with PMS compared with relapsing-remitting MS (RRMS; P ≤.02). MHI in people with PMS was associated with Expanded Disability Status Scale (EDSS; r range, 0.42-0.52) and 9-Hole Peg Test (9HPT; r range, 0.45-0.52) scores.
“A non-invasive, quantitative measurement of spinal cord pathology would be clinically valuable, given its critical involvement in motor, sensory, and autonomic deficits in MS. One promising quantitative magnetic resonance imaging (MRI) approach is MWI, which can be performed using multi-component T2 relaxation analysis to quantify the MR signal from different water environments within each voxel,” wrote first author Lisa Eunyoung Lee, MS, BSc, PhD candidate and research assistant, University of British Columbia, and colleagues.
Lee and colleagues analyzed MWI data collected at cord level C2/C3 on a 3T MRI scanner. They calculated MHI for whole cervical cord, global white matter, dorsal column, lateral and ventral funiculi. They also assessed correlations between MHI and EDSS, 9HPT, Timed 25-Foot Walk Test (T25WT) and disease duration.
Altogether, there were 35 participants with RRMS, 30 with PMS, and 28 healthy controls in the study. The participants with RRMS had an average age of 44 years (range, 26-61) and 26 were women (74%). The participants with PMS had an average age of 57 years (range, 48-65) and 19 were women (63%). Controls had an average age of 45 years (range, 27-65) and 18 were women (64%). Of the participants with PMS, 11 had primary PMS (PPMS) and 19 had secondary PMS (SPMS).
Participants with RRMS had an average disease duration of 11 years (range, 0.3-48) and a median EDSS score of 2.5 (range, 1.0-6.0). Participants with PMS had an average disease duration of 22 years (range, 1-43) and a median EDSS score of 4.0 (range, 2.0-7.5).
Lee and colleagues found that participants with PMS had higher MHI in the whole cervical cord (+9.5%; P = .04), global white matter (WM; +19%; P = .0009), dorsal column (+31%; P <.0001), and lateral funiculi (+17%; P = .01) compared to controls. No significant differences were seen from controls in ventral funiculi MHI.
Participants with PMS also had higher MHI compared to those with RRMS in global WM (+13%; P = .02) and dorsal column (+26%; P <.0001), with insignificant trends in whole cervical cord and lateral funiculi. Participants with RRMS did not have any significant differences in MHI from controls in any regions.
Researchers also analyzed MHI of all participants with MS and found that MHI was associated with EDSS score in global WM (r, 0.35; P = .005), dorsal column (r, 0.36; P = .004), and lateral funiculi (r, 0.33; P = .009). MHI was also associated with 9HPT scores in whole cervical cord (r, 0.40; P = .002), global WM (r, 0.47; P = .0002), dorsal column (r, 0.52; P <.0001), and lateral funiculi (r, 0.32; P = .02). Lastly, MHI was also associated with disease duration in global WM (r, 0.31; P = .01), dorsal column (r, 0.24; P = .05), and lateral funiculi (r, 0.30; P = .02). No significant associations were seen between MHI and T25W.
These significant associations were not seen in RRMS alone. PMS alone showed stronger associations between MHI and EDSS in whole cervical cord (r, 0.52; P = .004), global WM (r, 0.42; P = .02), and lateral funiculi (r, 0.46; P = .01) and between MHI and 9HPT in whole cervical cord (r, 0.48; P = .01), global WM (r, 0.45; P = .02) and dorsal column (r, 0.52; P = .005).
“[MWI] supplements conventional (clinical) MRI findings by providing additional information about biological changes within normal-appearing and lesional tissue. Therefore, MWI could serve as a valuable tool for monitoring therapeutic effects, disease progression, tissue repair, and neuroprotection in MS and other diseases involving myelin pathology,” Lee and colleagues concluded.