A Study of Imaging in Demyelinating Diseases

Inclusion Criteria: * Meet the requirements for one of the case or control groups. * MS patients undergoing neurologic evaluation procedures as part of Understanding Sex Differences in Multiple Sclerosis Spectrum of Demyelinating Disorders (IRB# 19-002807) Study or the Mayo Clinic Neurology Multiple Sclerosis Clinic. * Control participants without inflammatory-demyelinating diseases of the central nervous system * Capacity to sign consent. Exclusion Criteria: * Participants unable to lie down without moving for 20 minutes. * Women who are pregnant or cannot stop breast feeding for 24 hours. * For all patients and controls, any acute glucocorticoid (e.g., IV methylprednisolone or PO prednisolone) use within 2 weeks is an exclusion to limit medication interaction but preserve possible chronic systemic inflammation interaction with microglia activation metrics. Chronic disease modifying treatments in MS are allowed as these medications are not known to impact microglia activation. * Standard safety exclusionary criteria for MRI such as metallic foreign bodies, pacemaker, etc., since the quantitative PET data analysis is based on anatomic criteria that are established uniquely for each subject by registration to his/her MRI.