Maria R. Ponisio, MD
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Washington University in St. Louis (WU)
One of the most devastating complications of sickle cell anemia (SCA) is cerebral ischemic stroke, which occurs in approximately 11% of patients by their 14th birthday and may cause severe impairment in motor and/or cognitive function. The only proven therapy for prevention of strokes in children with sickle cell anemia is chronic blood transfusion therapy to reduce hemoglobin S (Hb S) to less than 30%. Indeed, the Stroke Prevention in Sickle Cell Anemia (STOP) trial established that transfusion therapy in children with transcranial Doppler velocities >200cm/sec reduced the incidence of stroke from 10% to 1%. Despite its efficacy, the risks of chronic transfusions include: blood borne viral infections, blood transfusion reactions, iron overload, and secondary hemochromatosis.Even more common are silent cerebral infarcts (abnormal findings on MRI without neurological symptoms of stroke), which are present in 20-30% of children with SCA. The Specific Aims: Aim 1. To gather preliminary data on the feasibility of using MR-OEF to image children with sickle cell anemia (SCA) to determine if the therapeutic effects of blood transfusion may be related to changes in cerebral hemodynamic and metabolic parameters. This aim requires 2 MRI scans pre and post transfusion. Aim 2. To determine if elevated regional oxygen extraction fraction (OEF) in children with SCA is a predictor of cerebral tissue at risk for developing an ischemic stroke. This aim requires 1 additional MRI scan at 1 year after enrollment.