Individual Cerebral Hemodynamic Oxygenation Relationships

This is a randomized controlled trial in patients who require clinical anesthesia. The main purpose of this study is to understand whether there are differences in the cerebral blood flow, and oxygen metabolism affected by two types of anesthesia: propofol or sevoflurane. Subjects who require clinical anesthesia for a clinical MRI and for whom the use of propofol and sevoflurane are in clinical equipoise will be offered to have the anesthesia they will receive during their MRI randomized. All eligible subjects will be asked to provide informed consent before participating in the study. Treatment: All patients will be screened to ensure propofol and sevoflurane are in clinical equipoise. Those who meet eligibility criteria, and who undergo the informed consent, will be randomize to receive propofol or sevoflurane during their MRI. Standard-of-care anesthesia safety, dose and monitoring will not be changed. During their MRI, additional images will be acquired that measure the cerebral blood flow and cerebral venous oxygenation. These additional images will take up-to 10 extra minutes to acquire. This will increase the duration each subject spends under anesthesia, and in the MRI scanner by up-to a total of 10 extra minutes. Safety Assessment: To ensure that either propofol or sevoflurane are in clinical equipoise, all patients will be screened by an anesthesiologist. The experiment will occur in the standard-of-care clinical MRI environment. All patient safety and monitoring will remain in place. Throughout the induction, maintenance and recovery from anesthesia, all procedures will occur in the standard of care environment and will be overseen by trained clinical personnel. Efficacy Assessment: Cerebral blood flow and metabolism MRIs will be collected from all subjects.