PILRA and perivascular space measurement: In total, 49 proteins were associated robustly with MRI-cSVD in CSF (41), plasma (4), or both (4), including three associated with both WMH and PVS: CTSB (Cathepsin B), a lysosomal protease involved in extracellular matrix (ECM) degradation, and two soluble isoforms deltaTM and M14 of PILRA (Paired Immunoglobin Like Type 2 Receptor Alpha), a microglial immunoreceptor.