Obstructive sleep apnea (OSA) is a significant contributor to co-morbid disease in obese children. Cerebral endothelial dysfunction and neurocognitive deficits have been linked to obesity-related OSA. However, the effect of the chronic hypoxic environment caused by untreated OSA on cerebrovascular health in the pediatric population remains unclear. Cerebrovascular reactivity (CVR) measured with BOLD MRI in response to a CO2 stimulus is a useful tool in the clinical assessment of cerebrovascular disease. This study seeks to understand the effect of OSA on the cerebrovascular health in obese pediatric patients through MRI assessment.