Standard protocol for DEXA scanning

Body composition is measured in anesthetized mice using a dual energy X-ray absorptiometry (DEXA) Scanner from Lunar/GE Medical Systems (PIXImus2, distributed by Faxitron X-Ray Corporation, Wheeling, IL). Each day, the DEXA scanner is calibrated for bone mineral density and percent fat content using the “phantom mouse” unit supplied with the machine. This calibration procedure is part of the quality control process and measurements for bone mineral density and percent fat must be within 2% of the expected value (in our case 0.0647g/cm2 and 11.9%, respectively) in order to proceed with animal scans.

Mice are anesthetized with tribromoethanol (250 mg/kg) or another anesthetic of choice and placed ventral side down on disposable plastic trays so that the entire body and tail are measured in the scan. Trays are positioned in the DEXA scanner so that the head is always oriented toward the left from the investigators point of view. After the scan is completed, mice are removed from the plastic tray and returned to their home cage to recover from anesthesia.

DEXA scans are analyzed using the PIXImus2 software (version 1.46.007). The head region is excluded from the analysis. Values for whole body bone mineral density (BMD, g/cm2), bone mineral content (BMC, g), bone area (cm2), total tissue mass (calculated by the software, g), total area (cm2), fat content (g), lean content (total tissue mass minus fat content, g) and percent fat (fat content divided by total tissue mass) are obtained. Body weight (g) is measured on a scale just prior to scanning and this value is reported as well.

Regions of interest (ROI’s) such as spine and femur can be selected and analyzed separately for bone mineral density and content.

Customized options

  • Analysis of regions of interest such as spine and femur to detect skeletal phenotypes
  • Measurements before and after surgical ovariectomy
  • Measurements before and after compound administration
  • Validation of DEXA results by chemical analysis of body composition

References

Nagy, TR and Clair, A-L. Precision and accuracy of dual-energy X-ray absorptiometry for determining in vivo body composition in mice. Obesity Res. 2000; 8:392-398. [PubMed: 10968731]

Pietrobelli, A, Formica, C, Wang, Z, Heymsfield, SB.  Dual-energy X-ray absorptiometry body composition model: review of physical concepts. Am. J. Physiol. 1996; 271:E941-E95 [PubMed: 8997211].

Pietrobelli, A, Wang, Z, Formica, C, Heymsfield, SB. Dual-energy X-ray absorptiometry: fat estimation errors due to variation in soft tissue hydration. Am. J. Physiol. 1998; 274:E808-E816 [PubMed: 9612238].

Beamer, WG, Donahue, LR, Rosen, CJ, Baylink, DJ. Genetic variability in adult bone density among inbred strains of mice. Bone 1996; 18:397 [PubMed: 8739896].

Klein, RF, Shea, M, Gunness, ME, Pelz, GB, Belknap, JK, Orwoll, ES. Phenotypic characterization of mice bred for high and low peak bone mass. J. Bone Mineral Res. 2001; 16:63-71 [PubMed: 11149491].