title: Prevalence and pattern of brown adipose tissue distribution of 18F-FDG in patients undergoing PET-CT in a subtropical climatic zone.
abstract: BACKGROUND
  The uptake of F-FDG in brown adipose tissue (BAT) may have important implications in understanding the pathophysiology of BAT and obesity. Because of the thermal implications of BAT uptake of F-FDG, this study aimed to contribute to existing knowledge by assessing patients scanned in a subtropical environment with particular reference to ethnicity.
  
  
  METHODS
  A retrospective study was carried out to determine the prevalence and pattern of BAT uptake in patients undergoing F-FDG PET-CT imaging in a PET facility located in a subtropical climatic zone. Standardized uptake values were obtained for regions of BAT uptake of F-FDG, and the distribution pattern was assessed according to anatomical region, sex, age, BMI and ethnicity.
  
  
  RESULTS
  Following a reveiw of a total of 386 scans, 38 patients showed BAT uptake of F-FDG (9.85%), with the mass and activity of BAT being greater in women than in men (11.95 and 6.88%, respectively). BAT uptake of F-FDG in the neck/supraclavicular, axillary and mediastinal regions was greater in adults whose BMI was less than 18 kg/m. However, perirenal BAT activity was shown to be greater in obese individuals. The frequency of BAT uptake of F-FDG was 55% in winter as against 45% during summer (P<0.012). There was no statistical difference in BAT uptake between black and white patients.
  
  
  CONCLUSIONS
  This study shows the pattern and prevalence of BAT in patients in a subtropical environment. Although the average seasonal temperatures are higher in a subtropical climate, a seasonal variation in BAT expression was observed, although there were no differences with respect to patient ethnicity.
authors.affiliation: Radiological and Imaging Sciences, Medical Physics, Medical School Queen’s Medical Centre, University of Nottingham, Nottingham, NG7 2UH, UK. alan.perkins@nottingham.ac.uk
authors.forename: Alan C
authors.initials: AC
authors.lastname: Perkins
authors.forename: Dahiru S
authors.initials: DS
authors.lastname: Mshelia
authors.forename: Michael E
authors.initials: ME
authors.lastname: Symonds
authors.forename: Mike
authors.initials: M
authors.lastname: Sathekge
mesh_terms: D002001:Adipose Tissue, Brown / Q000000981:diagnostic imaging* / Q000378:metabolism*; D000293:Adolescent; D000328:Adult; D001692:Biological Transport; D002648:Child; D002675:Child, Preschool; D005006:Ethnicity / Q000706:statistics & numerical data; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism; D006801:Humans; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D009928:Organ Specificity; D049268:Positron-Emission Tomography; D015995:Prevalence; D012621:Seasons; D014057:Tomography, X-Ray Computed; D014329:Tropical Climate; D055815:Young Adult
chemical_list: D019788:Fluorodeoxyglucose F18