Pharmacokinetics Distribution of Raltegravir by PET/MR

Inclusion Criteria: * Age ≥18 years * HIV infection * Initiated a combination ART (HAART) regimen Exclusion Criteria: * Screening absolute neutrophil count \<1,000 cells/mm3, platelet count \<70,000 cells/mm3, hemoglobin \< 8 mg/dL, estimated creatinine clearance \<40 mL/minute, aspartate aminotransferase \>100 units/L, alanine aminotransferase \>100 units/L. * Serious illness requiring hospitalization or parental antibiotics within the preceding 3 months. * Any vaccination 2 weeks prior to baseline (Day 0) visit and throughout the study period. * Concurrent treatment with immunomodulatory drugs, or exposure to any immunomodulatory drug in the preceding 16 weeks (e.g. corticosteroid therapy equal to or exceeding a dose of 15 mg/day of prednisone for more than 10 days, IL-2, interferon-alpha, methotrexate, cancer chemotherapy). NOTE: Use of inhaled or nasal steroid use is not exclusionary. * Pregnant or breastfeeding women. Females of childbearing potential must have a negative serum pregnancy test at screening and agree to use a double-barrier method of contraception throughout the study period. * Have a cardiac pacemaker or other indwelling foreign object that are contraindicated for MR imaging.