title: Determinants of physiologic 18F-FDG uptake in brown adipose tissue in sequential PET/CT examinations.
abstract: OBJECTIVE
  The aim of this study was to assess independent predictors of 2-deoxy-2-[(18)F]fluoro-D-glucose ((18)F-FDG) uptake in brown adipose tissue (BAT) in patients undergoing repeated positron emission tomography (PET)/computed tomography (CT) scans.
  
  
  METHODS
  Eight hundred forty-eight (mean age 50.9 ± 16 years) patients in whom PET/CT scan was repeated (mean interval 5 ± 1.5 months) constituted the study group. (18)F-FDG uptake in characteristic areas of BAT, with CT density of adipose tissue, greater than background soft-tissue activity was considered as evidence of BAT uptake. Both distribution and maximum standardized uptake values (SUVmax) were registered. Clinical and anamnestic data were collected for each patient.
  
  
  RESULTS
  (18)F-FDG uptake in BAT was present in 8.6% patients at first scan. Independent predictors of presence of uptake were age (younger), gender (female), body mass index (lower), and maximum outdoor temperature (lower). Age was the only independent predictor of BAT (18)F-FDG uptake distribution, while SUVmax was related to both age and outdoor temperature. Independent determinants of persistence of BAT (18)F-FDG uptake at second PET/CT were outdoor temperature at time of second scan and extension of metabolically active BAT at first scan.
  
  
  CONCLUSIONS
  Age, body mass index, and outdoor temperature are significant determinants of BAT evidence at (18)F-FDG PET/CT. Moreover, extension of BAT and outdoor temperature are the strongest determinants of persistence of BAT evidence on (18)F-FDG PET/CT in repeated scan.
authors.affiliation: Dipartimento di Scienze Biomorfologiche e Funzionali, Facoltà di Medicina e Chirurgia, Università degli Studi di Napoli Federico II, Napoli, Italy. pace@unina.it
authors.forename: Leonardo
authors.initials: L
authors.lastname: Pace
authors.forename: Emanuele
authors.initials: E
authors.lastname: Nicolai
authors.forename: Domenico
authors.initials: D
authors.lastname: D'Amico
authors.forename: Francesco
authors.initials: F
authors.lastname: Ibello
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Della Morte
authors.forename: Barbara
authors.initials: B
authors.lastname: Salvatore
authors.forename: Laura Micol
authors.initials: LM
authors.lastname: Pizzuti
authors.forename: Marco
authors.initials: M
authors.lastname: Salvatore
authors.forename: Andrea
authors.initials: A
authors.lastname: Soricelli
mesh_terms: D002001:Adipose Tissue, Brown / Q000000981:diagnostic imaging / Q000378:metabolism*; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D049268:Positron-Emission Tomography; D014057:Tomography, X-Ray Computed; D055815:Young Adult
chemical_list: D019788:Fluorodeoxyglucose F18