title: Temporal relation between temperature change and FDG uptake in brown adipose tissue.
abstract: OBJECTIVE
  It has been reported that the prevalence of (18)F fluorodeoxyglucose (FDG) uptake in brown adipose tissue (BAT) is related to outdoor temperature, i.e., more frequent during the colder periods of the year. The purpose of this study was to assess the temporal relationship between BAT FDG uptake and temperature. We correlated the prevalence of BAT with average temperatures (divided into five temperature ranges) of seven different durations.
  
  
  METHODS
  One thousand four hundred ninety-five consecutive FDG Positron emission tomography (PET) studies in 1,159 patients (566 male and 593 female, mean age = 60.4 years) were retrospectively reviewed. FDG uptake with distinct patterns compatible with BAT was identified by a consensus of two readers. The local daily average temperature from January 2000 to November 2003 (beginning 60 days before the date of first PET scan) were obtained, and 2-, 3-, 7-, 14-, 30-, and 60-day average temperatures before the date of a PET study were calculated. The prevalence of BAT FDG uptake was correlated with these various average temperatures.
  
  
  RESULTS
  The daily, 2-day, 3-day, and 7-day average temperature had an inverse relation with the prevalence of BAT, i.e., the lower the temperature, the higher prevalence of BAT. When the temperature was averaged over 14 days or longer, this inverse relationship between the temperature and the prevalence of BAT was no longer preserved.
  
  
  CONCLUSIONS
  Our data suggest that increased FDG uptake in BAT occurs more often as an acute response to cold weather (1-7 days) rather than to prolonged periods of average cold weather.
authors.affiliation: Division of Nuclear Medicine, Department of Radiology, Mount Sinai School of Medicine, New York, NY, USA. ckim@umm.edu
authors.forename: Sunhee
authors.initials: S
authors.lastname: Kim
authors.forename: Borys R
authors.initials: BR
authors.lastname: Krynyckyi
authors.forename: Josef
authors.initials: J
authors.lastname: Machac
authors.forename: Chun K
authors.initials: CK
authors.lastname: Kim
mesh_terms: D002001:Adipose Tissue, Brown / Q000000981:diagnostic imaging* / Q000378:metabolism*; D000293:Adolescent; D000328:Adult; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics*; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D013696:Temperature; D013997:Time Factors
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18