AbstractPatients with sickle cell disease (SCD) are at elevated risk of silent cerebral infarcts and strokes; however, they frequently lack established stroke risk factors (eg, macrovascular arterial steno-occlusion) and, as such, the mechanisms underlying such events are incompletely characterized. This study evaluated cerebral metabolism with respect to imaging markers of vascular shunting in 143 participants with SCD, including 73 pediatric (aged 6-17 years) and 70 adult (aged 18-40 years) participants. Participants completed clinical and cerebral imaging assessments using 3-Tesla brain magnetic resonance imaging (MRI) to quantify cerebral hemometabolic measures. Vascular shunting was assessed in each patient using a previously published ordinal venous hyperintensity score (VHS) of 0, 1, or 2 on cerebral blood flow-weighted MRI. Relationships between age group (pediatric vs adults) and hemometabolic measures for varying VHS were investigated using 2-way analysis of variance. Participants with VHS of 2, indicative of the most rapid arteriovenous transit, had significantly reduced blood oxygen content (CaO2; 10.90 ± 1.69 mL O2 per 100 mL blood), oxygen extraction fraction (OEF; 33.52% ± 5.54%), and cerebral metabolic rate of oxygen consumption (CMRO2; 2.91 ± 0.69 mL O2 per 100g tissue per minute) compared with their counterparts with VHS = 0 (CaO2 = 12.42 ± 1.58 mL O2 per 100 mL blood; OEF = 39.03% ± 3.80%; CMRO2 = 3.77 ± 0.84 mL O2 per 100 g tissue per minute) or VHS = 1 (CaO2 = 11.86 ± 1.73 mL O2 per 100 mL blood; OEF = 36.37% ± 5.11%; CMRO2 = 3.59 ± 0.78 mL O2 per 100 g tissue per minute). Both pediatric and adult patients with SCD presenting with greater imaging evidence of vascular shunting had mildly reduced OEF and CMRO2. These findings highlight that imaging markers of vascular shunting are associated with significant, albeit mild, evidence of reduced OEF and CMRO2 in patients with SCD.
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