title: Increased FDG uptake in association with reduced extremity fat in HIV patients.
abstract: BACKGROUND
  HIV lipodystrophy - characterized by peripheral lipoatrophy, with or without central fat accumulation - confers increased metabolic risk. However, the functional activity of HIV lipodystrophic tissue in relation to metabolic risk has yet to be fully explored in vivo through the use of non-invasive imaging techniques. This study assesses the relationship between FDG uptake in various fat depots and metabolic/immune parameters among subjects with HIV lipodystrophy.
  
  
  METHODS
  Lipodystrophic men on antiretroviral therapy underwent whole-body (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET)/computed tomography scans and detailed metabolic/immune phenotyping.
  
  
  RESULTS
  FDG uptake in the subcutaneous adipose tissue (SAT) of the extremities (mean standardized uptake value [SUV] of the arm and leg SAT) was found to correlate with the degree of peripheral lipoatrophy (r=0.7; P=0.01). Extremity SAT FDG uptake was positively associated with homeostasis model assessment of insulin resistance (HOMA-IR; r=0.6; P=0.02) and fasting hyperinsulinaemia (r=0.7; P=0.01), while fat percentage of extremities was not. Furthermore, extremity SAT FDG uptake was significantly associated with CD4(+) T-cell count (r=0.6; P=0.05). In multivariate modelling for HOMA-IR, extremity SAT FDG uptake remained significant after controlling for body mass index and tumour necrosis factor-α (R(2) for model =0.71, P=0.02; SUV in the extremity SAT β-estimate 12.3, P=0.009).
  
  
  CONCLUSIONS
  In HIV lipodystrophic patients, extremity SAT FDG uptake is increased in association with reduced extremity fat and may contribute to insulin resistance. Non-invasive assessments of in situ inflammation using FDG-PET may usefully complement histological and gene expression analyses of metabolic dysregulation in peripheral fat among HIV-positive patients.
authors.affiliation: Division of Musculoskeletal Imaging and Intervention, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA.
authors.forename: Martin
authors.initials: M
authors.lastname: Torriani
authors.forename: Markella V
authors.initials: MV
authors.lastname: Zanni
authors.forename: Kathleen
authors.initials: K
authors.lastname: Fitch
authors.forename: Eleni
authors.initials: E
authors.lastname: Stavrou
authors.forename: Miriam A
authors.initials: MA
authors.lastname: Bredella
authors.forename: Ruth
authors.initials: R
authors.lastname: Lim
authors.forename: Aaron M
authors.initials: AM
authors.lastname: Cypess
authors.forename: Steven
authors.initials: S
authors.lastname: Grinspoon
mesh_terms: D050153:Abdominal Fat / Q000378:metabolism / Q000473:pathology; D001823:Body Composition; D005121:Extremities / Q000473:pathology*; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism; D039682:HIV-Associated Lipodystrophy Syndrome / Q000175:diagnosis* / Q000276:immunology / Q000378:metabolism; D006801:Humans; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D049268:Positron-Emission Tomography; D050151:Subcutaneous Fat / Q000378:metabolism / Q000473:pathology*; D014057:Tomography, X-Ray Computed
chemical_list: D019788:Fluorodeoxyglucose F18