Document Detail


Quantitative body composition analysis in awake mice and rats by magnetic resonance relaxometry.
MedLine Citation:
PMID:  15536224     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
OBJECTIVE: Magnetic resonance (MR) relaxometry has recently been introduced for noninvasive body composition analysis in awake mice. The purpose of the present study was to extend the method to rats and to introduce calibration procedures that render MR relaxometry fully quantitative. RESEARCH METHODS AND PROCEDURES: Proton T(2) MR relaxometry at 4.7 Tesla was used for body composition analyses in 700 awake mice and 400 rats of different strains and conditions. Relaxograms calculated from the signal decays observed with multi-spin-echo acquisition provided well-separated contributions of tissue water and fat. Analysis of fat composition was carried out in vivo using (13)C-MR spectroscopy. Evolution of body composition in rats was assessed during drug treatment. RESULTS: MR relaxometry for noninvasive body composition analysis in laboratory rodents was implemented on a standard MR scanner, and a throughput of >30 animals per hour was achieved. Excellent linearity and reproducibility with coefficients of variance as low as 2.5% and 1.7% were obtained in mice and rats, respectively. The lean mass-to-water ratio (mice, 1.35 +/- 0.03; rats, 1.39 +/- 0.04) and the proton density of fat (mice, 8.1 +/- 0.2; rats, 8.9 +/- 0.2 g/mol) were determined from cross-sectional data. Fat composition analysis by (13)C-MR spectroscopy corroborated these findings and yielded information on the average acyl chain length (16.3 +/- 1.6) and contributions of saturated (27 +/- 3%), monounsaturated (22 +/- 2%), and polyunsaturated (51 +/- 3%) fatty acids. Longitudinal assessments in rats treated with sibutramine and dexfenfluramine showed dose-related changes in body composition. DISCUSSION: T(2) MR relaxometry backed by solid calibration provides a powerful means for rapid quantitative body composition analysis in awake mice and rats that is suitable for serial investigations in pharmaceutical research.
Authors:
Basil Künnecke; Philippe Verry; Agnès Bénardeau; Markus von Kienlin
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Publication Detail:
Type:  Comparative Study; Journal Article    
Journal Detail:
Title:  Obesity research     Volume:  12     ISSN:  1071-7323     ISO Abbreviation:  Obes. Res.     Publication Date:  2004 Oct 
Date Detail:
Created Date:  2004-11-10     Completed Date:  2005-04-08     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  9305691     Medline TA:  Obes Res     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1604-15     Citation Subset:  IM    
Affiliation:
Magnetic Resonance Imaging and Spectroscopy, PRBD-M, Building 68/05A, F. Hoffmann-La Roche Ltd., Grenzacherstrasse 124, CH-4070 Basel, Switzerland. basil.kuennecke@roche.com
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MeSH Terms
Descriptor/Qualifier:
Animals
Anti-Obesity Agents / therapeutic use*
Body Composition*
Calibration
Cross-Sectional Studies
Cyclobutanes
Dexfenfluramine
Magnetic Resonance Spectroscopy / methods,  standards*
Mice
Mice, Inbred AKR
Mice, Inbred C57BL
Mice, Obese
Obesity / diet therapy,  drug therapy*
Rats
Rats, Sprague-Dawley
Rats, Wistar
Rats, Zucker
Reproducibility of Results
Sensitivity and Specificity
Weight Loss / physiology
Chemical
Reg. No./Substance:
0/Anti-Obesity Agents; 0/Cyclobutanes; 106650-56-0/sibutramine; 3239-44-9/Dexfenfluramine

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