TSPO-PET-measurable neuroinflammation associates with brain atrophy in multiple sclerosis

Background In neurodegenerative conditions, neuroaxonal damage and tissue destruction lead to central nervous system atrophy. In multiple sclerosis (MS), widespread glial activation can contribute to disease progression and nervous tissue destruction. We aimed to assess the cross-sectional association between brain atrophy and diffuse glial activation. Methods One-hundred-and-twenty-eight participants with MS (92 relapsing-remitting and 36 progressive MS) and 73 healthy controls (HC) underwent brain MRI and positron emission tomography (PET) using 18-kDa translocator protein (TSPO)-binding radioligand [ 11 C]-PK11195. Associations between [ 11 C]-PK11195 distribution volume ratios (DVR) and brain parenchymal fractions were examined using correlation and multivariable linear regression analyses. Results In MS, higher normal-appearing white matter (NAWM) DVR correlated with smaller whole brain (ρ=–0.38, p