title: Seasonal variation in the effect of constant ambient temperature of 24 degrees C in reducing FDG uptake by brown adipose tissue in children.
abstract: OBJECTIVE
  It has been shown that warming patients prior to and during (18)F-FDG uptake by controlling the room temperature can decrease uptake by brown adipose tissue (BAT). The aim of this study is to determine if this effect is subject to seasonal variation.
  
  
  METHODS
  A retrospective review was conducted of all patients referred for whole-body (18)F-FDG PET between December 2006 and December 2008. After December 2007, all patients were kept in the PET injection room at a constant 24 degrees C for 30 min before and until 1 h following FDG administration. Patients over 22 years of age and those who received pre-medication known to reduce FDG uptake by BAT were excluded. One hundred and three patients were warmed to 24 degrees C prior to scanning. The number of patients showing uptake by BAT in this group was compared to a control group of 99 patients who underwent PET prior to December 2007 when the injection room temperature was 21 degrees C.
  
  
  RESULTS
  Uptake by BAT occurred in 9% of studies performed after patient warming (24 degrees C), compared to 27% of studies performed on the control group (21 degrees C) (p < 0.00001). The effect of warming on decreasing FDG accumulation in BAT was statistically significant in the winter (p < 0.005) and summer (p < 0.001). However, in the spring and autumn, though the effect of warming on decreasing FDG accumulation in BAT was evident, it was not statistically significant (p > 0.05).
  
  
  CONCLUSIONS
  Maintaining room temperature at a constant 24 degrees C for 30 min prior to and 1 h after IV tracer administration significantly decreases FDG uptake by BAT in children. This effect is greatest in the summer and winter.
authors.affiliation: Department of Imaging, Division of Nuclear Medicine, Dana-Farber Cancer Institute, Harvard Medical School, 44 Binney Street, Boston, MA 02115, USA. kzukotynski@partners.org
authors.forename: Katherine A
authors.initials: KA
authors.lastname: Zukotynski
authors.forename: Frederic H
authors.initials: FH
authors.lastname: Fahey
authors.forename: Stephen
authors.initials: S
authors.lastname: Laffin
authors.forename: Royal
authors.initials: R
authors.lastname: Davis
authors.forename: S Ted
authors.initials: ST
authors.lastname: Treves
authors.forename: Frederick D
authors.initials: FD
authors.lastname: Grant
authors.forename: Laura A
authors.initials: LA
authors.lastname: Drubach
mesh_terms: D052437:Adipocytes, Brown / Q000378:metabolism*; D000293:Adolescent; D001692:Biological Transport; D002648:Child; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism*; D006801:Humans; D008297:Male; D012189:Retrospective Studies; D012621:Seasons; D013696:Temperature; D055815:Young Adult
chemical_list: D019788:Fluorodeoxyglucose F18