title: Noninvasive measurements of body composition and body water via quantitative magnetic resonance, deuterium water, and dual-energy x-ray absorptiometry in cats.
abstract: OBJECTIVE
  To compare quantitative magnetic resonance (QMR), dual-energy x-ray absorptiometry (DXA), and deuterium oxide (D2O) dilution methods for measurement of total body water (TBW), lean body mass (LBM), and fat mass (FM) in healthy cats and to assess QMR precision and accuracy.
  
  
  METHODS
  Domestic shorthair cats (58 and 32 cats for trials 1 and 2, respectively).
  
  
  METHODS
  QMR scans of awake cats performed with 2 units were followed by administration of D2O tracer (100 mg/kg, PO). Cats then were anesthetized, which was followed by QMR and DXA scans. Jugular blood samples were collected before and 120 minutes after D2O administration.
  
  
  RESULTS
  QMR precision was similar between units (coefficient of variation < 2.9% for all measures). Fat mass, LBM, and TBW were similar for awake or sedated cats and differed by 4.0%, 3.4%, and 3.9%, respectively, depending on the unit. The QMR minimally underestimated TBW (1.4%) and LBM (4.4%) but significantly underestimated FM (29%), whereas DXA significantly underestimated LBM (9.2%) and quantitatively underestimated FM (9.3%). A significant relationship with D2O measurement was detected for all QMR (r(2) > 0.84) and DXA (r(2) > 0.84) measurements.
  
  
  CONCLUSIONS
  QMR was useful for determining body composition in cats; precision was improved over DXA. Quantitative magnetic resonance can be used to safely and rapidly acquire data without the need for anesthesia, facilitating frequent monitoring of weight changes in geriatric, extremely young, or ill pets. Compared with the D2O dilution method, QMR correction equations provided accurate data over a range of body compositions.
authors.affiliation: Nestlé Purina PetCare Basic Research Group, Nestlé Research Center, 2 Research S, St Louis, MO 63164, USA. brian.zanghi@rd.nestle.com
authors.forename: Brian M
authors.initials: BM
authors.lastname: Zanghi
authors.forename: Carolyn J
authors.initials: CJ
authors.lastname: Cupp
authors.forename: Yuanlong
authors.initials: Y
authors.lastname: Pan
authors.forename: Delphine G
authors.initials: DG
authors.lastname: Tissot-Favre
authors.forename: Norton W
authors.initials: NW
authors.lastname: Milgram
authors.forename: Tim R
authors.initials: TR
authors.lastname: Nagy
authors.forename: Howard
authors.initials: H
authors.lastname: Dobson
mesh_terms: D015502:Absorptiometry, Photon / Q000379:methods / Q000662:veterinary*; D000375:Aging; D000818:Animals; D001823:Body Composition / Q000502:physiology*; D001834:Body Water / Q000502:physiology*; D002415:Cats; D003903:Deuterium; D005260:Female; D008279:Magnetic Resonance Imaging / Q000379:methods / Q000662:veterinary*; D008297:Male; D014867:Water / Q000737:chemistry
chemical_list: D014867:Water; D003903:Deuterium