New tracer could reveal hidden immune activity in brain diseases

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

* INCLUSION CRITERIA: In order to be eligible to participate in this study, an individual must meet all of the following criteria: Multiple Sclerosis Inclusion Criteria * Enrolled in the NINDS Natural History Study for MS (protocol 89-N-0045) * Able to understand, and willing to sign, a written, informed consent document. * Willing to comply with all study procedures and available for the duration of the study. * Male or female, aged \>=18. * Diagnosis of MS according to the 2017 revision of the McDonald diagnostic criteria48 (in the presence or absence of a clinical relapse). PML Inclusion Criteria * Enrolled in the NINDS Natural History Study for PML (protocol 13-N-0017) * Able to understand and willing to sign a written, informed consent document * Willing to comply with all study procedures and available for the duration of the study. * Male or female, aged \>=18. * Diagnosis of definite PML according to 2013 AAN Consensus Criteria49 or PML-IRIS based on clinical, radiological and laboratory evidence. Patients with Known or Suspected Neuroinflammatory Diseases and Evidence of Open BBB Inclusion Criteria -Clinical evaluation suggesting an inflammatory disorder of the central nervous system other than MS or PML. Other confirmed neuroinflammatory disorders may include -MOGAD, NMOSD, Behcet's syndrome, and neurosarcoidosis. Unconfirmed, though suspected cases of neuroinflammation may also be included. * Recent brain MRI (within 1 month) with gadolinium enhancement indicating open BBB. * Able to understand and willing to sign a written, informed consent document. * Willing to comply with all study procedures and available for the duration of the study. * Male or female, aged \>=18. EXCLUSION CRITERIA: An individual who meets any of the following criteria will be excluded from participation in this study: * Pregnant or lactating. * Contraindications for MRI gadolinium contrast administration or 3T MRI. * History of, or current diagnosis with, concomitant medical or clinical conditions that would adversely affect participation in this study. * Weighs \> 350 lb. (158 kg; weight limit for the scanner table) or is unable to fit within the MRI or PET imaging gantry. * Severe claustrophobia unresponsive to oral anxiolytics. * Has an alkaline phosphatase level greater than 2x ULN (unless known to have non-liver related disorder) OR AST greater than 1.5 x ULN OR ALT greater than 1.5 x ULN. * Has a total bilirubin \>1.5X ULN, unless known to have elevated bilirubin due to nonliver related disorder or Gilbert s. * Creatinine clearance \< 60 mL/min as estimated by the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) * For females of reproductive potential: inability to use highly effective contraception for at least one month prior to screening and during study participation.