RecruitingDiagnostic testIndividual Cerebral Hemodynamic Oxygenation Relationships (ICHOR 1)This is an observational study 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 different types of anesthesia. Subjects who require clinical anesthesia for a clinical MRI and for whom the use of anesthetics for the exam are in clinical equipoise are asked to join the study. All eligible subjects will be asked to provide informed consent before participating in the study.