Assessment of volume fraction and fabric in the distal radius using HR-pQCT

• Published in: Bone (New York, N.Y.) Vol. 45; no. 5; pp. 909 - 917
• Main Authors: Varga, P, Zysset, P.K
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 01-11-2009; Elsevier
• Subjects: Aged, 80 and over; Anisotropy; Biological and medical sciences; Bone Density - physiology; Distal radius; Fabric; Female; Fundamental and applied biological sciences. Psychology; HR-pQCT; Humans; Image registration; Male; Organ Size; Orthopedics; Radiographic Image Interpretation, Computer-Assisted; Radius - anatomy & histology; Radius - diagnostic imaging; Tomography, X-Ray Computed - methods; Trabecular bone; Vertebrates: anatomy and physiology, studies on body, several organs or systems; X-Ray Microtomography; Image registration; Distal radius; HR-pQCT; Trabecular bone; Fabric; Radius; Morphology; Bone trabeculae
• ISSN: 8756-3282; 1873-2763
• DOI: 10.1016/j.bone.2009.07.001

Abstract The aim of this study was to investigate the capabilities of the state of the art HR-pQCT technique to predict mineral content, volume fraction and fabric of trabecular bone structure compared to the gold standard μCT. Four cadaveric human forearms were scanned with HR-pQCT and the dissected radius epiphyses with μCT. After registering the images, bone mineral density (BMD), volume fraction (BV/TV) and fabric were computed on corresponding cubical regions of interest for both image sources. In particular, the effect of the segmentation procedure on BV/TV was analyzed. Assessment of fabric was performed with three different methods comparing their efficiency and robustness against resolution change. The results showed that in order to achieve optimal results at the lower image resolution, different filtering and thresholding approaches needed to be selected for different tasks. Therefore, to preserve BV/TV, the BMD-based volume fraction provided best match with the reference values of μCT, while in case of Mean Intercept Length (MIL) fabric a Gaussian filter and a histogram-based threshold were optimal. Using the latter, MIL was found to be more robust against resolution change than the other approaches. Additionally, we proposed a linear model for describing the mathematical transformation that the second order fabric tensor undergoes when the resolution of the input images changes. As a conclusion, we found that the investigated properties of trabecular bone structure can be adequately predicted from the lower resolution technique that is available in vivo for peripheral bones, when proper image processing and corrections are applied.