Validation of a high-resolution X-ray computed tomography system to measure murine adipose tissue depot mass in situ and longitudinally.
BACKGROUND
Obesity is a significant public health concern with considerable academic and industrial research effort underway to discover novel drugs to treat this disease. The aim of this study was to validate a recently developed high-resolution X-ray computed tomography (micro CT) system capable of measuring murine adipose tissue depot mass in situ.


METHODS
The micro CT was used to generate a series of cross-sectional X-ray images from which individual adipose tissue depot mass was quantified. Four individual adipose tissue depots were studied: inguinal subcutaneous, epididymal, retroperitoneal, and mesenteric. The relationship between micro CT-derived adipose tissue mass and adipose mass measured gravimetrically was determined. The effect of strain (C57/Bl6, C3H/HeNCR1BR, and db/db) and age (49 vs. 99 days) on adipose tissue depot mass was studied.


RESULTS
Validation studies in which adipose tissue depot mass was determined by micro CT and by gravimetry were conducted in the three strains of mice at 49 and 99 days of age. The correlation of micro CT and gravimetric measures of adipose tissue mass exceeded 90% in all strains at 99 days, and in the C57/Bl6 and C3H/HeNCR1BR strains at 49 days. At 49 days, the correlation in the db/db strain was 82%. Micro CT methodology distinguished both age and strain differences in the adipose tissue depots studied (P<.0001, in all cases).


CONCLUSIONS
Micro CT is a valid method to quantify the mass of individual adipose tissue depots in mice. This method of determining adipose tissue mass is not a terminal procedure; thus, this methodology may be particularly useful for the longitudinal assessment of the effects of drug intervention on adipose tissue depot mass.
Hildebrandt
Audrey L
AL
Cardiovascular and Metabolic Diseases, Pfizer Global Research and Development, Eastern Point Road, Groton, CT 06340, USA.
Kelly-Sullivan
Dawn M
DM
Black
Shawn C
SC
D000273:Adipose Tissue / Q000000981:diagnostic imaging*; D000375:Aging; D000818:Animals; D001835:Body Weight; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D009765:Obesity / Q000000981:diagnostic imaging; D009929:Organ Size; D015203:Reproducibility of Results; D013045:Species Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*