Relating perivascular imaging measures to longitudinal lesion evolution and chronic inflammation in multiple sclerosis

Background: Perivascular space (PVS) alterations may be associated with acute and chronic inflammatory activity in people with multiple sclerosis (pwMS). Purpose: Investigate whether diffusion tensor image analysis along the PVS (DTI-ALPS) or PVS number/volume are associated with lesion evolution in pwMS over 5-years. Methods: 182 patients (142 relapsing-remitting MS [pwRRMS] and 40 progressive MS [pwPMS]) underwent clinical and MRI examinations at baseline and 5-year follow-up. All pwMS were assessed for contrast enhancing lesions (CELs), T2 lesions, T1 lesions and cortical lesions (CLs). A subset of 86 pwMS were analyzed for presence of paramagnetic rim lesions (PRL). Associations between DTI-ALPS, PVS number/volume and lesion types were evaluated using regression and ANCOVA models, adjusting for age, sex, disease duration and normal-appearing white matter mean diffusivity, with false discovery rate correction for multiple comparisons, resulting in q values. Results: In pwRRMS, baseline DTI-ALPS was associated with baseline CEL number (q < 0.001), T1 lesion number (q = 0.013), T2 lesion volume (q = 0.037) and T1 lesion volume (q < 0.002). It was associated with accumulation of new/enlarging CL (q = 0.013) and T1 lesions (q = 0.007), absolute change in T1 lesion volume (q = 0.025) and trended with newly appearing PRLs (q = 0.066). Absolute 5-year change in PVS volume was related to PRL presence at baseline (q = 0.018). Conclusion: PVS alterations are associated with lesion evolution in pwRRMS.