Individual Cerebral Hemodynamic Oxygenation Relationships - ICHOR 4

Inclusion Criteria: * Patients who are scheduled for a clinically indicated MRI at the sponsor institution. * Patients who are able to tolerate an MRI. * Patients who require clinical anesthesia for their MRI. * Patients with conditions not believed to alter oxygen metabolism or blood flow in the brain, including but not limited to patients with orthopedic indications, undescended testicles, hernia repairs, term equivalent age scans. * Patients who have no medical conditions that make the use of propofol or dexmedetomidine better for their clinical outcome. * Patients between birth and up-to 7 year of age. * Patients with conditions known to alter oxygen metabolism or blood flow in the brain, e.g. traumatic brain injury, hypoxic ischemic encephalopathy, tumor. Exclusion Criteria: * Patients with an MRI-incompatible device or implant (e.g. pacemakers, stents) * Preterm infants less than 25 weeks postmenstrual age (PMA) at the time of the scan. * Patients who are clinically too unstable to extend their MRI by up-to 10 minutes. * Patients who do not require clinical anesthesia. * Patients at risk for propofol infusion syndrome (known severe metabolic acidosis, hyperkalemia, lipemia, rhabdomyolysis, hepatomegaly, renal failure, ECG ST segment elevation, and/or cardiac failure) * Patient at risk for sensitivity to volatile halogenated anesthetic agents (known congenital Long QT Syndrome or patients taking drugs that can prolong the QT interval), * Patients with Perioperative Hyperkalemia (known neuromuscular disease, particularly Duchenne muscular dystrophy)