Predicting Trabecular Bone Stiffness from Clinical Cone-Beam CT and HR-pQCT Data; an In Vitro Study Using Finite Element Analysis.

Eva Klintström,Örjan Smedby,Torkel B Brismar,Rodrigo Moreno,Benjamin Klintström,Dieter H Pahr,M A Pérez

doi:10.1371/journal.pone.0161101

Abstract

Stiffness and shear moduli of human trabecular bone may be analyzed in vivo by finite element (FE) analysis from image data obtained by clinical imaging equipment such as high resolution peripheral quantitative computed tomography (HR-pQCT). In clinical practice today, this is done in the peripheral skeleton like the wrist and heel. In this cadaveric bone study, fourteen bone specimens from the wrist were imaged by two dental cone beam computed tomography (CBCT) devices and one HR-pQCT device as well as by dual energy X-ray absorptiometry (DXA). Histomorphometric measurements from micro-CT data were used as gold standard. The image processing was done with an in-house developed code based on the automated region growing (ARG) algorithm. Evaluation of how well stiffness (Young’s modulus E3) and minimum shear modulus from the 12, 13, or 23 could be predicted from the CBCT and HR-pQCT imaging data was studied and compared to FE analysis from the micro-CT imaging data. Strong correlations were found between the clinical machines and micro-CT regarding trabecular bone structure parameters, such as bone volume over total volume, trabecular thickness, trabecular number and trabecular nodes (varying from 0.79 to 0.96). The two CBCT devices as well as the HR-pQCT showed the ability to predict stiffness and shear, with adjusted R2-values between 0.78 and 0.92, based on data derived through our in-house developed code based on the ARG algorithm. These findings indicate that clinically used CBCT may be a feasible method for clinical studies of bone structure and mechanical properties in future osteoporosis research.

Highlights

Osteoporosis is a major health problem that concerns almost all developed countries and there are big differences in the incidence of hip fractures
Images of the radius specimens, for studying changes and biomechanical properties associated with osteoporosis, were obtained with four imaging methods including two cone beam computed tomography (CBCT) devices; 3D Accuitomo 80 referred to as CBCT(A) and NewTom 5G referred to as CBCT(N), one HRpQCT device; Scanco XtremeCT, one micro-CT device; Scanco μCT 40 and one dual energy X-ray absorptiometry (DXA) machine; Discovery A S/N 82934
The segmentation of high-resolution peripheral quantitative computed tomography (HR-peripheral Quantitative computed tomography (pQCT)) data was made using implementations of two different segmentation methods, both with the in-house-developed code based on the Automated Region Growing (ARG) algorithm and with the software dedicated for the XtremeCT device from Scanco Medical

Summary

Introduction

Osteoporosis is a major health problem that concerns almost all developed countries and there are big differences in the incidence of hip fractures. In studies from the 1990’s an alternative device, peripheral Quantitative computed tomography (pQCT), was demonstrated to deliver precise in vivo evaluations of trabecular and cortical density as well as the bone mineral content (BMC) of selected skeletal sites [9]. PQCT was found to give strong correlations with micro-CT regarding trabecular bone parameters like trabecular number and mean trabecular separation [10] Another well-described method for visualizing the trabecular bone structure in patients is high-resolution peripheral quantitative computed tomography (HR-pQCT). There is a risk that magnetic-field dependent susceptibility artefacts may cause overestimation of bone trabeculae [16]

Objectives

Methods

Results

Conclusion