The goal of this clinical trial is to understand whether there are differences in the cerebral blood flow, and oxygen metabolism affected by two types of anesthesia: Propofol or Dexmedetomidine. Subjects who require clinical anesthesia for a clinical MRI and for whom the use of Propofol and Dexmedetomidine are in clinical equipoise will be offered to have the anesthesia they will receive during their MRI randomized.
* Change in cerebral blood flow (ml blood/100g/min)
* Change in cerebral metabolic rate of oxygen (ml O2/100g/min)
Researchers will compare Propofol (Group A) to Dexmedetomidine (Group B) to see if compare the hemodynamic response to anesthesia.
Participants will be randomized to receive one of two equally safe anesthetics (Propofol or Dexmedetomidine).