Shrinking multiple sclerosis lesions are characterized by a more destructive phenotype than expanding lesions

Motivation: Slowly expanding lesions (SEL) have gained significant attention as a biomarker of chronic active multiple sclerosis (MS) lesions, however, one study1 suggests that all MS lesions tend to shrink over a long period of time. Goal(s): The objective of this work is to investigate the microstructure of expanding lesions (EL), shrinking lesions (SL), and stable lesions. Approach: EL and SL were computed using deformation-based volumetric MRI and microstructure was investigated using quantitative T1 and multi-shell diffusion MRI. Results: SL showed a more destructive phenotype at baseline when compared to EL, while stable lesions were considerably less destructive. Impact: This preliminary study underlies the necessity of considering the full spectrum of multiple sclerosis (MS) lesions, especially MRI-evolving lesions, whether shrinking or expanding, in MS research to extend our knowledge of the disease pathophysiology.