Simulation of the Influence of Material Properties and Image Quality on HRQCT-Based Bone Densitometry

JAIME PEÑA; SONJA WALDHAUSEN; GRAEME CAMPBELL; REINHARD BARKMANN; FELIX THOMSEN; CLAUS-C. GLÜER

Beckenridge, CO

Workshop; 19th International Bone Densitometry Workshop; 2012

Although BMD as measured with single-energy QCT (SEQCT) is known to be influenced by fatty bone marrow, it is unclear to what extent BV/TV or segmented BMD (segBMD) measures are affected. To gain a better understanding, we used Matlab (R2012a, Natick, MA) to analyze the influence of image noise and voxel-size on a CT-image depicting a simulation of trabecular bone.Artificial trabecular bone images with plate-like structures of 0.12 mm thickness and 0.6 mm height and fixed true BV/TV=0.193 immersed in different water and fat volume fractions (0.4 to 0.74) were created. Image voxel-size (10 to 160 μm), convolution filter size and additive Gaussian noise (normal distribution with std. deviations ranging from 1 to 350 mg/cm³) were other input parameters used to estimate BMD, BV/TV and segBMD.For the above mentioned range of water and fat volume fractions BMD varied from 140 to 173 mg/cm. The measurements were consistent for all simulated voxel-sizes and noise levels. Table1 lists BV/TV and segBMD results for some combinations of voxel-size and noise levels using two threshold settings.Table1. BV/TV and segBMD results obtained using two threshold settings for some combinations of noise level and voxel-sizes.The results show that fatty-marrow and image quality related effects like voxel-size and noise require the choice of specific threshold settings to obtain meaningful BV/TV and segBMD results.