Use of axial X-ray microcomputed tomography to assess three-dimensional trabecular microarchitecture and bone mineral density in single comb white leghorn hens

Department of Animal and Poultry Science, University of Guelph, Guelph, Ontario, Canada N1G 2W1.

Axial x-ray microcomputed tomography is a cost-effective technique with the potential to assess bone mineral density (mg/cc) in both cortical and cancellous bone in Single Comb White Leghorn hens. The technique requires little sample preparation and involves relatively simple data processing. The system described in this research is based on compact fan-beam type tomography, using a tungsten-anode x-ray tube with a relatively small focal spot (approximately 5 microm), coupled with a high-resolution x-ray detector system (approximately 10 microm). To produce a real 3-D data set using microcomputed tomography, x-ray projection views were acquired at 720 equally spaced angular positions (0.5 degrees) around the object of interest. These groups of views were then used to reconstruct a computed tomography image. A test grid with orthogonal test lines was used to calculate bone volume and bone surface. From these calculations, parallel plate equations were used to derive trabecular architectural parameters such as average trabecular plate thickness and average trabecular plate separation. Three-dimensional microarchitecture was evaluated using specialized stereological analysis software. Significant relationships between apparent bone mineral density (mg/cc) and 3-D structure were observed in femoral specimens from 66-wk-old Single Comb White Leghorn hens.