Inclusion Criteria:  Control Participants: Males and females over the age of 18 years hospitalized and receiving intensive care for diagnosis's other than COVID-19 or an acute neurological disease and who were not diagnosed (clinically or with PCR testing) with COVID-19. Case Participants: Males and females over the age of 18 years who had been hospitalized at Mayo Clinic Hospital for treatment of COVID-19 confirmed by PCR test. We acknowledge that some participants may be unable to consent due to underlying medical conditions; an eligible proxy may provide the informed consent and provide a signature on the designated line. Women of childbearing age, between the ages of 18 to 55, must complete a negative pregnancy test. Minority individuals over the age of 18 years will be eligible to enroll.  Exclusion Criteria:  Males and females, under the age of 18 years. Participants with PET/MRI non-compatible devices. Claustrophobia. Allergies to study related procedures. Pregnant , incarcerated, or institutionalized subjects will not be included in the study.