Magnetization transfer ratio (MTR) is a measure of demyelination and tissue destruction in MS.  MTR values are not only useful to detect structural changes but if found to correlate with functional decline, may help further quantify disease severity in MS.

Twenty-one patients were included in this cross sectional study. We attempted to trend functional disease progression against MTR changes in gray matter (GM), normal appearing white matter (NAWM) and lesional WM. We compared MTR values from WM, lesional WM and GM to functional scales at baseline and Year 1. We used the Expanded Disability Status Scale (EDSS), and the multiple sclerosis functional composite (MSFC) which consists of the paced auditory serial addition test -3 (PASAT-3), 9 hole peg test (9 HPT) and 25 foot walk test. A 2- tailed Pearson Correlation analysis was used to compare the MTR WM values to the functional scales.

Our results showed that GM MTR has a significant inverse relationship with upper extremity function measured by the 9HPT (-0.475, p 0.029) and lesional WM MTR is associated with cognitive ability and processing of information measured by PASAT-3 (-0.544, p-0.016). EDSS marginally correlates with WM and GM MTR (-0.046, p0.043) but not with lesional MTR. No such relationship was found with the 25 foot walk test.

MTR values can be useful to further quantify functional progression of MS when used in combination with PASAT -3 and 9HPT as well as with EDSS but not with 25 foot timed walk. GM MTR and lesional MTR might be potential biomarkers of upper extremity function and cognitive processing respectively. Further studies with larger samples are needed to validate our results.