GFAP and Cerebral cortical atrophy: In this regard, magnetic resonance imaging (MRI) markers like cortical atrophy [6], spinal cord atrophy and paramagnetic rim lesions (PRL) [2, 7] as well as serum-biomarkers like glial fibrillary acidic protein (GFAP) [8] were shown to be associated with higher PIRA risk.