Intra-abdominal fat burden discriminated in vivo using proton magnetic resonance spectroscopy.
OBJECTIVE
To assess proton magnetic resonance spectroscopy (1H-MRS) as a means to distinguish among mice with disparate intra-abdominal body fat compositions, and to measure changes in intra-abdominal fat burden during weight loss and regain.


METHODS
Intra-abdominal fat burden was analyzed as a ratio of integrated areas under the curves of fat to water (1)H-MRS signals collected from a region of interest standardized across B6.V-Lep(ob), C57BL/6, and A-ZIP/F mice that exhibited various genotypically related body fat compositions, ranging from obese (B6.V-Lep(ob)) to minimal body fat (A-ZIP/F). 1H-MRS analysis of fat burden was compared with intra-abdominal fat volume and with a single cross-sectional intra-abdominal fat area calculated from segmented magnetic resonance images. Similar measurements were made from obese B6.V-Lep(ob) mice before, during, and after they were induced to lose weight by leptin administration.


RESULTS
Relative amounts of intra-abdominal fat analyzed by 1H-MRS differed significantly according to body composition and genotype of the three strains of mice (p < 0.05). Intra-abdominal fat assessed by 1H-MRS correlated with both intra-abdominal fat volume (r = 0.88, p < 0.001) and body weight (r = 0.82, p < 0.001) among, but not within, all three genotypes. During weight loss and regain, there was a significant overall pattern of changes in intra-abdominal fat quantity that occurred, which was reflected by 1H-MRS (p = 0.006).


CONCLUSIONS
Results support the use of localized 1H-MRS for assessing differences in intra-abdominal fat. Refinements in 1H-MRS voxel region of interest size and location as well as instrument precision may result in improved correlations within certain body compositions.
Walling
Brent E
BE
Molecular Pathology Unit, Center for Cancer Research, National Cancer Institute, 37 Convent Drive, Building 37, Room 2000, Bethesda, MD 20892, USA.
Munasinghe
Jeeva
J
Berrigan
David
D
Bailey
Michael Q
MQ
Simpson
R Mark
RM
D000818:Animals; D019540:Area Under Curve; D001823:Body Composition / Q000502:physiology*; D050218:Body Fat Distribution; D005260:Female; D005838:Genotype; D050152:Intra-Abdominal Fat / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D051379:Mice; D008810:Mice, Inbred C57BL; D008820:Mice, Obese; D009765:Obesity / Q000473:pathology*; D010641:Phenotype; D011522:Protons; D015430:Weight Gain / Q000502:physiology; D015431:Weight Loss / Q000502:physiology
D011522:Protons