Bone Mineral Density Measurement of Rats Using Dual-energy X-ray Absorptiometry: Precision of In Vivo Measurements for Various Skeletal Sites with or without Repositioning

Oh, Dong Hyun; Jung, Jae Ho; Woo, Sang Keun; Cheon, Gi Jeong; Kim, Byung Il; Choi, Chang Woon; Lim, Sang Moo

Abstract

PURPOSE: Bone mineral density (BMD) measurements need to be precise enough to be capable of detecting small changes in bone mass of rats. Using a regular dual-energy X-ray absorptiometry (DXA), we measured many BMD of various skeletal sites in rats to examine precision of DXA in relation to the repositioning on the bones of rats.
MATERIALS AND METHODS
Using DXA and small animal software, scans were performed 4 times in all 12 male rats without repositioning (Group 1a). Another four scans for 6 of 12 rats were done with repositioning between scans (Group 2). Customized regions of interest (ROIs), encapsulate the right hind limb, L1-4, skull and pelvic bones were drawn at each measurement. The precision of the measurements was evaluated by measuring the coefficient of variation (CV) of four measurements of BMD at each skeletal site of all rats with or without repositioning. Significance of differences between group 1b (six rats out of group 1a, which were come under group 2) and group2 were evaluated with Wilcoxon Signed Rank Sum Test.
RESULTS
CVs obtained at different skeletal sites of all measurements in Group 1b and 2. It was 3.51+/-1.20, 2.62+/-1.20 for the hindlimb (p=0.173), 3.83+/-2.02, 4.59+/-2.02 for L1-4 (p=0.600), 3.73+/-1.87, 1.53+/-0.89 for skull (p=0.046), and 2.92+/-0.60, 1.45+/-0.60 for pelvic bones (p=0.075).
CONCLUSION
Our study demonstrates that the DXA technique has the precision necessary when used to assess BMD for various skeletal sites in rats regardless of repositioning.