Investigating the Utility of Demyelination Tracer [18F]3F4AP in Controls and Multiple Sclerosis Subjects

Inclusion Criteria:

* Subjects must be ≥18 and \<65 years of age;
* Able to understand and provide informed consent prior to study procedures

Exclusion Criteria:

* Subjects with known structural brain disease (e.g. brain tumor or stroke);
* Any contraindication to MRI and/or PET, including:

  * Subjects with life vest;
  * Subjects with implanted heart device (e.g. ICD, Pacemaker);
  * Subjects with metallic fragment or foreign body;
  * Subjects with other form of devices or prosthesis that are not MRI compatible, such as insulin pump, joint replacement, hearing aid, cochlear implant, permanent contraceptive devices, etc.;
  * Subjects with severe claustrophobia
  * Relative or absolute contraindication to Dotarem contrast:
* history of renal disease including acute or chronic severe renal insufficiency (glomerular filtration rate \<60 mL/min/1.73m2);
* history of diabetes mellitus, systemic lupus, multiple myeloma, nephrogenic systemic fibrosis, and other co-morbidities;
* History of hypersensitive reactions to Dotarem and/or gadolinium contrast agent;
* Radiation exposure exceeds current Radiology Department guidelines (i.e., 50 mSv in the prior 12 months);
* Female subjects only: Positive serum pregnancy test, or lactating, or possibility of pregnancy cannot be ruled out prior to dosing;
* Inability to provide written informed consent;
* Any clinically significant acute or unstable physical or psychiatric condition, judged by the investigators based on medical history or screening physical examination, to be incompatible with the study;
* Any physical or psychiatric condition judged by the investigators to be incompatible with the study, based on medical history or screening physical examination;
* Abnormal results on blood tests judged by the investigators to be incompatible with the study.