Hyperpolarized Carbon Metabolic Imaging in Multiple Sclerosis

Inclusion criteria: In order to be eligible to participate in this study, an individual must meet all of the following criteria: 1. Subjects must be 18 years or older. 2. Relapsing remitting MS, naïve to DMTs for the past two years minimum 3. Patients must be naive to anti-CD20 therapy with plans to begin the therapy as part of their physician's multiple sclerosis treatment plan. The patients must remain on a form of anti-CD20 therapy for the entirety of their enrollment in the study. 4. Patients enrolled will be screened for at least one MS lesion with a 10mm diameter in one plane. Exclusion criteria: 1. Treatment with corticosteroids within 30 days prior to screening. 2. Patients unwilling or unable to undergo MR imaging, including patients with contra-indications to MRI, such as cardiac pacemakers or non-compatible intracranial vascular clips. 3. Poorly controlled hypertension, defined as either systolic \>160 or diastolic \>110. The addition of anti-hypertensives to control blood pressure is allowed for eligibility determination. 4. Congestive Heart Failure ≥ NYHA Class II. 5. History of clinically significant EKG abnormalities, including QT prolongation or a family history of prolonged QT syndrome. 6. Myocardial infarction within 6 months of study entry. 7. Individuals who are pregnant. Individuals of childbearing potential (defined below) must agree to undergo a urine pregnancy test prior to participating in the study scans. Pregnant individuals are excluded because there is an unknown but potential risk for adverse effects in the unborn child secondary to administration of HP 13C pyruvate to the study participant. A female is considered to not be of childbearing potential (regardless of sexual orientation, having undergone a tubal ligation, or remaining celibate by choice), if they meet either of the following two criteria: (1) has reached a postmenopausal state (≥ 12 continuous months of amenorrhea with no identified cause other than menopause); or (2) has undergone surgical sterilization (i.e., hysterectomy and/or bilateral oophorectomy for removal of uterus and/or ovaries). 8. Individuals who are breastfeeding/chestfeeding. Breastfeeding/chestfeeding individuals are excluded because there is an unknown but potential risk for adverse effects in the unborn/nursing child secondary to administration of HP 13C pyruvate to the study participant. Breastfeeding/chestfeeding should be discontinued before administration of HP 13C pyruvate. 9. Known hypersensitivity to HP 13C pyruvate or any of its excipients. 10. History of cancer within five years of enrollment date and/or history of chemotherapy within two years of enrollment date. 11. Any dental braces or permanent or undetachable metals in the jaw or face. 12. Clinically significant cardiac, metabolic, hematologic, hepatic, immunologic, urologic, endocrinologic, neurologic, pulmonary, psychiatric, dermatologic, allergic, renal, or other major diseases that in the PI's judgment may affect the interpretation of study results or patient safety. 13. Individuals with any condition or social circumstance that, in the opinion of the investigator, would impair the participant's ability to comply with study procedures. 14. Glomerular filtration rate (GFR) of less than 60 mL/min/1.73 m² on baseline visit or subsequent study visits, history of kidney disease or history of hypersensitivity to gadolinium contrast agent. 15. Baseline EDSS \>6.5