title: Postoperative changes in body composition--comparison of bioelectrical impedance analysis and magnetic resonance imaging in bariatric patients.
abstract: BACKGROUND
  Roux-en-Y gastric bypass (RYGB) result in a marked reduction of body fat and also visceral fat (VF) decrease up to 36 % in 16 weeks. This leads to positive effects on cardiometabolic risks, which are known to be correlated with the occurrence of VF. This study analyzed the validity of bioelectrical impedance analysis (BIA) for determining VF in the postoperative course. In addition, magnetic resonance imaging (MRI) was performed for prediction of whole VF in bariatric patients on the basis of a single slice.
  
  
  METHODS
  Eighteen patients, who underwent RYGB (18), were included in this study. MRI and BIA measurements were performed 1 day before surgery, as well as 6, 12, and 24 weeks after surgery.
  
  
  RESULTS
  During the postoperative observation period, we found a significant decrease of both subcutaneous fat (SF) and VF. SF measured by MRI was highly correlated with the level of body fat shown by BIA. In contrast, the VF volume, as determined by MRI, showed no correlation with the body fat measured by BIA. In addition, we were able to show a significant correlation between MRI measured VF volume and the particular single-layer fat area.
  
  
  CONCLUSIONS
  Compared to the widely used bioelectrical impedance analysis to measure changes in body composition after bariatric procedures, a single-layer MRI was superior in determining VF. Single-layer MRI may be a better tool to recognize changes of VF after bariatric procedures.
authors.affiliation: UMM, University Medical Center Mannheim, Department of Surgery, Heidelberg University, Mannheim, Germany, mirko.otto@umm.de.
authors.forename: Mirko
authors.initials: M
authors.lastname: Otto
authors.forename: Julia
authors.initials: J
authors.lastname: Färber
authors.forename: Stefan
authors.initials: S
authors.lastname: Haneder
authors.forename: Henrik
authors.initials: H
authors.lastname: Michaely
authors.forename: Peter
authors.initials: P
authors.lastname: Kienle
authors.forename: Till
authors.initials: T
authors.lastname: Hasenberg
mesh_terms: D015502:Absorptiometry, Photon; D000273:Adipose Tissue / Q000473:pathology; D000328:Adult; D001823:Body Composition; D001837:Body Weights and Measures / Q000379:methods*; D017097:Electric Impedance; D005260:Female; D005500:Follow-Up Studies; D015390:Gastric Bypass / Q000534:rehabilitation*; D006801:Humans; D050152:Intra-Abdominal Fat / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009767:Obesity, Morbid / Q000378:metabolism / Q000473:pathology / Q000601:surgery*; D011184:Postoperative Period; D050151:Subcutaneous Fat / Q000473:pathology
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