DUAL-ENERGY X-RAY ABSORPTIOMETRY FOR HISTOLOGIC BONE SECTIONS

In fundamental osteoporosis research precise and accurate assessment o f the mineral quantity in histological bone sections is of particular importance when studying the local effects of implants releasing bone modulating agents. A potentially useful technique to estimate the bone mineral density (BMD) is dual-energy X-ray absorptiometry (DXA). A hi ghly collimated (0.13 mm) Hologic 2000 with a line spacing and point r esolution of 0.13 mm was used, The mineral content was measured in reg ions of 3.1 mm(2). A ceramic hydroxyapatite (CHA) phantom,vas develope d as a reference standard, The phantom was made of a single-phase hydr oxyapatite starting powder by compressing and sintering at 1000 degree s C. The true density was 3.14 a 0.001 g/cm(3), The calcium/phosphorus ratio was close to the theoretical one of 1.67, The mean precision er ror expressed as the coefficient of variation (CV) of the mineral dens ity (MD) measurements of the phantoms with thicknesses of 1, 2, and 3 mm was 0.2%, Embedded undecalcified alveolar bone sections of dogs (0. 0015-1 mm in thickness) were scanned simultaneously with a phantom 1 m m in thickness. The precision error (CV) of the BMD measurements calcu lated by DXA for sections greater than or equal to 0.1 mm and with a B MD greater than or equal to 0.14 g/cm(2) was 0.81%, There was a linear relationship between the BMD calculated by DXA and the estimated BMD in the histological bone sections by means of the true density of the phantom, It is concluded that DXA using a standard CHA phantom is a pr ecise and accurate method to measure MD changes as small as 1% in hist ological bone areas of 3.1 mm(2) provided that the loss or gain in BMD is greater than or equal to 0.14 g/cm(2).