Bone Abstracts

In clinical research protocols, HR-pQCT images (XtremCT Scanco, voxel size: 82 (μm³) are carried out to evaluate trabecular and cortical bone changes induced by osteoporosis and treatments. Micro-computed tomography (μ-CT) has become a standard tool for examination of trabecular and cortical bone in 3D.

The purpose of this study is to evaluate the accuracy of cortical and trabecular measurements derived from HR-pQCT images with morphological measurements from synchrotron radiation (SR) μ-CT.

Thirty tibias specimens (mean age: 82.2±9.7 years) were scanned at 3.5 cm from the tibial pilon with the XtremCT using the usual manufacturer acquisition protocol. Samples of cortical and trabecular bone were harvested at the posterior part of the tibia and imaged on ID19 beamline (ESRF, Grenoble) with a voxel size of 7.5 μm³. We performed site-matched analyses on the HR-pQCT images with the manufacturer software (HR_local analysis) comparatively to SR micro-CT images. For HR-local analysis, the cortical outcomes were: volumetric bone density (gHA/cm³) (Dcomp), cortical thickness (Ct.Th, mm) and the trabecular bone parameters: bone volume (BV/TV,%), trabecular thickness (Tb.Th, mm), trabecular spacing (Tb.Sp, mm) and trabecular number (Tb.N, per mm). Using the CTAn Skyscan software, the following cortical parameters from SR μCT acquisitions were obtained: Porosity (PoV/TV,%), pore diameter (Po.Dm, mm), pore spacing (Po.Sp, mm), pore number (Po.N, per mm). Ct.Th_SR was manually measured. The trabecular parameters were BV/TV_SR(%), Tb.Th_SR, Tb.Sp_SR, Tb.N_SR. Pearson correlation coefficients (r) were used to compare HR-pQCT and SR μCT parameters. The Ct.Th was correlated to Ct.Th_SR (r=0.61**; Table 1).

Conclusion: For cortical bone, Dcomp is predominantly related to porosity and for trabecular bone, the most related HR-pQCT parameters are their counterparts derived from the SR μCT images.