Regional oxygen extraction predicts border zone vulnerability to stroke in sickle cell disease

Objective To determine mechanisms underlying regional vulnerability to infarction in sickle cell disease (SCD) by measuring voxel-wise cerebral blood flow (CBF), oxygen extraction fraction (OEF), and cerebral metabolic rate of oxygen utilization (CMRO 2 ) in children with SCD. Methods Participants underwent brain MRIs to measure voxel-based CBF, OEF, and CMRO 2 . An infarct heat map was created from an independent pediatric SCD cohort with silent infarcts and compared to prospectively obtained OEF maps. Results Fifty-six participants, 36 children with SCD and 20 controls, completed the study evaluation. Whole-brain CBF (99.2 vs 66.3 mL/100 g/min, p p 2 (3.7 vs 2.5 mL/100 g/min, p 2 in this region, which encompassed the CBF nadir, was low relative to all white matter ( p Conclusions Elevated OEF in the deep white matter identifies a signature of metabolically stressed brain tissue at increased stroke risk in pediatric patients with SCD. We propose that border zone physiology, exacerbated by chronic anemic hypoxia, explains the high risk in this region.