Gray Matter Proton Density may be Related to Disability in Secondary Progressive MS

Quantitative magnetic resonance imaging (qMRI) may be a good tool for assessing disease status among patients with secondary progressive multiple sclerosis (SPMS), according to the results of a study published in the journal PLOS One. Authored by Rene-Maxime Gracien, MD, of the Department of Neurology at Goethe University in Frankfurt, Germany, and colleagues, the study investigated the relationship between gray matter and clinical disability.

MRI is the tool most often used to support the diagnosis of MS, but the researchers assert that in SPMS “diffuse microstructural changes in GM [gray matter], caused by global inflammation and neurodegeneration, are not visible on routine clinical MRI.” Changes in GM can, however, be measured by qMRI. The researchers say qMRI “techniques allow for the direct measurement of tissue parameters in vivo, providing a window into the microstructural tissue composition and its changes in MS.”

The researchers report that “this study investigates cortical and deep GM damage in SPMS patients using qMRI measurements of absolute PD [proton density] and T1 values as potential imaging surrogates of disease state and disability.” In order to investigate, 11 patients with SPMS were matched to 11 healthy controls.

The results showed that the SPMS patients had greater proton density in the cerebral cortex, thalamus, putamen, and pallidum, leading the authors to say, “Attractively, our observations suggest that PD may be a suitable parameter to assess neurodegenerative changes in SPMS.” There were T1 differences, as well: “Cortical and whole GM T1 relaxation time was prolonged in our SPMS group, and there was a trend for T1 prolongation in the thalamus,” said the researchers.

The authors wanted to see if there was some association between the qMRI readings and EDSS, and so performed a correlation analysis and found “the quantitative tissue parameter PD in GM was closely related to disability in our SPMS cohort” they said. Additionally, they report finding “a significant correlation with the EDSS could also be shown for cortical and whole NAGM [normal appearing gray matter] T1.”

Future studies, with more detailed data such as psychological or additional clinical scores, could provide additional information, and may eventually be used to “guide therapy for individual patients,” say the researchers.