title: Measurement of interscapular brown adipose tissue of mice in differentially housed temperatures by chemical-shift-encoded water-fat MRI.
abstract: OBJECTIVE
  To determine differences in fat-signal fraction (FF) from chemical-shift-encoded water-fat MRI of interscapular BAT in mice housed at different ambient temperatures (Ta ).
  
  
  METHODS
  C57BL/6J male mice (8 weeks old) were singly housed at 16°C, 23°C, or 30°C (n = 16/group) for 4 weeks. Measures included food intake, body weight (both measured weekly) and body composition (at baseline, 2, and 4 weeks post-thermal exposure); chemical-shift-encoded water-fat MRI was performed on a 9.4 Tesla Bruker magnet with respiratory gating and anesthesia at 4 weeks post-thermal exposure.
  
  
  RESULTS
  A significant inverse relationship between food intake and Ta was evidenced (P < 0.0001). Lean mass was similar among groups, while total fat mass was significantly different among groups ([mean ± SE]: 30°C = 5.10 ± 0.19 g; 23°C = 4.18 ± 0.16 g; 16°C = 3.48 ± 0.54 g; P < 0.0001). Mean BAT-FF was positively related to Ta (means: 30°C = 79.4%; 23°C = 61.8%; 16°C = 50.9%; P < 0.0001).
  
  
  CONCLUSIONS
  These cross-sectional results demonstrate that MRI measurement of FF within the interscapular BAT in mice reflects recent functional status of the tissue, with a lower Ta leading to a significantly reduced BAT-FF, indicative of the tissue's involvement in thermogenesis.
authors.affiliation: Department of Nutrition Sciences, University of Alabama at Birmingham, Birmingham, Alabama, USA; Nutrition Obesity Research Center, University of Alabama at Birmingham, Birmingham, Alabama, USA; Diabetes Research Training Center, University of Alabama at Birmingham, Birmingham, Alabama, USA.
authors.forename: Daniel L
authors.initials: DL
authors.lastname: Smith
authors.forename: Yongbin
authors.initials: Y
authors.lastname: Yang
authors.forename: Houchun H
authors.initials: HH
authors.lastname: Hu
authors.forename: Guihua
authors.initials: G
authors.lastname: Zhai
authors.forename: Tim R
authors.initials: TR
authors.lastname: Nagy
mesh_terms: D002001:Adipose Tissue, Brown / Q000033:anatomy & histology / Q000502:physiology*; D000818:Animals; D001831:Body Temperature / Q000502:physiology*; D001834:Body Water / Q000166:cytology / Q000502:physiology*; D004435:Eating / Q000502:physiology*; D017753:Ecosystem; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D015203:Reproducibility of Results; D012540:Scapula / Q000033:anatomy & histology / Q000502:physiology*; D012680:Sensitivity and Specificity; D022722:Thermogenesis / Q000502:physiology*
keywords: body composition; brown adipose tissue; fat-signal fraction; thermogenesis; water-fat MRI; white adipose tissue