SWI brush sign of cerebral parenchymal veins in central nervous system diseases.

Brush sign (BS) was first reported as prominent hypointensity of deep medullary veins and subependymal veins on T2*-weighted images at 3 T MRI in patients with acute stroke in the territory of the middle cerebral artery. Subsequently, BS in central nervous system (CNS) diseases such as moyamoya disease, cerebral venous thrombosis, and Sturge-Weber syndrome was also described on susceptibility-weighted imaging (SWI), and the clinical implications of BS were discussed. The purpose of this review is to demonstrate BS on SWI in various CNS diseases and its mechanisms in the above-mentioned diseases. We also explain the clinical implications of this finding in each disease.