title: Brown fat at PET/CT: correlation with patient characteristics.
abstract: OBJECTIVE
  To assess the prevalence of brown fat in patients with cancer, compare demographic characteristics of those with and those without brown fat, and correlate these characteristics with the mean and maximum standardized uptake values of brown fat.
  
  
  METHODS
  This case-control study was institutional review board approved and HIPAA compliant. Informed consent was waived. Reports of 12 195 consecutive positron emission tomography/computed tomography examinations performed in 6867 patients between January 2004 and November 2008 were reviewed for documented fluorodeoxyglucose (FDG) uptake in brown fat (n = 298). Control patients (n = 298) without brown fat were chosen and matched for age, sex, and month and year of examination. Age, sex, weight, body mass index, ethnicity, and examination stage (initial vs restaging) were compared between groups. Paired Student t test, χ(2) test, Pearson correlation coefficient, and analysis of variance were used for statistical analysis.
  
  
  RESULTS
  Uptake of FDG in brown fat was demonstrated in 298 of 6867 (4.33%) patients. Prevalence of brown fat was significantly higher in female (5.9% [211 of 3587]) than in male patients (2.65% [87 of 3280]; P < .001). Those with brown fat had significantly lower body weight (147.5 lb ± 3.8 vs 168.61 lb ± 5.0; P < .001) and body mass index (24.3 ± 0.54 vs 27.6 ± 0.77; P < .001) than control patients. There was no significant difference in the prevalence of brown fat among ethnic groups. The maximum standardized uptake value of brown fat had a significant inverse correlation with age (r = -0.3, P < .001).
  
  
  CONCLUSIONS
  Patients with brown fat were more likely to be female and thinner than those without brown fat. Younger patients were more likely to have higher maximum standardized uptake values of brown fat.
authors.affiliation: Department of Abdominal Imaging and Interventional Radiology, Massachusetts General Hospital, 55 Fruit St, White 270, Boston, MA 02114, USA. cgcronin@partners.org
authors.forename: Carmel G
authors.initials: CG
authors.lastname: Cronin
authors.forename: Priyanka
authors.initials: P
authors.lastname: Prakash
authors.forename: Gilbert H
authors.initials: GH
authors.lastname: Daniels
authors.forename: Giles W
authors.initials: GW
authors.lastname: Boland
authors.forename: Mannudeep K
authors.initials: MK
authors.lastname: Kalra
authors.forename: Elkan F
authors.initials: EF
authors.lastname: Halpern
authors.forename: Edwin L
authors.initials: EL
authors.lastname: Palmer
authors.forename: Michael A
authors.initials: MA
authors.lastname: Blake
mesh_terms: D002001:Adipose Tissue, Brown / Q000000981:diagnostic imaging*; D000704:Analysis of Variance; D001466:Barium Sulfate / Q000493:pharmacokinetics; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics; D006801:Humans; D007479:Iopamidol / Q000493:pharmacokinetics; D008297:Male; D064847:Multimodal Imaging; D009369:Neoplasms / Q000000981:diagnostic imaging; D049268:Positron-Emission Tomography; D015995:Prevalence; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D012737:Sex Factors; D014057:Tomography, X-Ray Computed
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D001466:Barium Sulfate; D007479:Iopamidol