Evaluation of Cancellous Bone Density from C3 to L5 in 11 Body Donors: CT Versus Micro-CT Measurements

Introduction: Comparative studies on Hounsfield units (HU) and bone volume fraction (BVF%) for the demonstration of cancellous bone density in the entire spine and in the various intravertebral regions are rare. The aim of the present study was to determine HU in various segments and sectional planes (sagittal, axial, coronary) of the spine and their description in the context of bone density measurement on micro-CT, as well as the significance of the values for bone loss and fracture risk. Materials/Methods: The spines of 11 body donors were analyzed by means of high-resolution spiral CT and micro-CT. Vertebral deformities were identified on sagittal reformations and classified. Cancellous bone density in the individual vertebrae from C3 to L5, expressed in HU, was measured on CT images (in all 242 vertebral bodies). For this purpose, a manually positioned ROI was established in mid-vertebral cancellous bone in the axial, sagittal, and coronary planes. Using a Jamshidi® needle, we obtained 726 specimens from prepared vertebrae extracted from three quadrants (QI: right-sided edge, QII: central, QIII: left-sided edge) and analyzed these on a micro-CT device (SKYSCAN 1172, RJL Micro & Analytic GmbH, Germany). The study design with multiple measurements was reflected by a General Linear Model Repeated Measures. The model was adjusted to the bone density values of both procedures (HU, BVF%) in the viewed sectional planes and quadrants for 22 vertebrae, with the predictors gender and fracture status, controlled for age and body mass index (BMI). Analysis of variance provided estimations of density values and comparisons of several subgroups. Results: All spines were osteoporotic. Both procedures revealed a significant reduction in cancellous bone density from C3 to L5 (p ≤ 0.018). Gender (p = 0.002) and fracture status (p = 0.001) have an impact on bone density: men have higher bone density values than women; cases with fewer fractures also have higher bone density values. CT revealed both effects (p = 0.002 for each) with greater clarity. HU on CT measurements in the axial plane showed higher density values than in the sagittal or coronary planes. CT measurement profiles along the spine as well as along the individual profiles of the 11 body donors were independent of the measured quadrants, but the micro-CT measurements were not. Discussion: The craniocaudal reduction in bone density was demonstrated in different degrees of clarity by the two procedures. Likewise, the procedure-related visualization of differences in cancellous bone density between genders, fracture groups, sectional planes, and quadrants indicates the need for a better understanding of the advantages of each procedure for patient-oriented approaches to the diagnosis of osteoporosis. Future research should be focused on the determination of standard values and their clinical application for the prevention and treatment of osteoporosis.