Abstract TP210: Oxygen Extraction Fraction is Increased in the Borderzone Region of Healthy Young Adults

Background: We have previously shown that the borderzone region demonstrates ischemic physiology, with low cerebral blood flow (CBF) and increased oxygen extraction fraction (OEF), in pediatric sickle cell anemia (SCA). This region is vulnerable in SCA as evidenced by increased infarct burden. Here we studied healthy adults to determine if borderzone physiology exists in the absence of apparent vascular disease. Methods: Healthy (N=17, 33 ± 9 yr) and SCA (N=13, 28 ± 7 yr) adults were recruited from a tertiary care SCA clinic. Individuals with vascular risk factors or chronic medical or neurological diseases were excluded. SCA subjects were excluded for stroke, vasculopathy, or transfusion therapy. Brain MRIs were prospectively obtained including: T1, FLAIR, dynamic susceptibility contrast (CBF), and asymmetric spin echo (OEF). Within each subject, 3 regions of low CBF were derived by normalizing CBF to its peak CBF. For gray matter (GM), regions were: < 25th%, 25-50th%, and 50-75th% of mean thalamic CBF. ...