Morphometric analysis of trabecular bone thickness using different algorithms (original) (raw)
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A comparative study of trabecular bone micro-structural measurements using different CT modalities
Physics in Medicine and Biology, 2020
Osteoporosis, characterized by reduced bone mineral density and micro-architectural degeneration, significantly enhances fracture-risk. There are several viable methods for trabecular bone micro-imaging, which widely vary in terms of technology, reconstruction principle, spatial resolution, and acquisition time. We have performed an excised cadaveric bone specimen study to evaluate different CT-imaging modalities for trabecular bone microstructural analysis. Excised cadaveric bone specimens from the distal radius were scanned using micro-CT and four in vivo CT imaging modalities: HR-pQCT, dental CBCT, wholebody MDCT, and extremity CBCT. A new algorithm was developed to optimize soft thresholding parameters for individual in vivo CT modalities for computing quantitative bone volume fraction maps. Finally, agreement of trabecular bone micro-structural measures, derived from different in vivo CT imaging, with reference measures from micro-CT imaging was examined. Observed values of most trabecular measures, including trabecular bone volume, network area, transverse and plate-rod micro-structure, thickness, and spacing, for in vivo CT modalities were higher than their micro-CT-based reference values. In general, HR-pQCT-based trabecular bone measures were closer to their reference values as compared to other in vivo CT modalities. Despite large differences in observed values of measures among modalities, high linear correlation (r Î [0.94 0.99]) was found between micro-CT and in vivo CT-derived measures of trabecular bone volume, transverse and plate micro-structural volume, and network area. All HR-pQCT-derived trabecular measures, except the erosion index, showed high correlation (r Î [0.91 0.99]). The plate-width measure showed a higher correlation (r Î [0.72 0.91]) among in vivo and micro-CT modalities than its counterpart binary plate-rod characterization-based measure erosion index (r Î [0.65 0.81]). Although a strong correlation was observed between micro-structural measures from in vivo and micro-CT imaging, large shifts in their values for in vivo modalities warrant proper scanner calibration prior to adopting in multi-site and longitudinal studies.
Osteoporosis International, 2008
Summary In vivo high-resolution peripheral quantitative micro-CT (HR-pQCT) is a new modality for imaging peripheral sites like the distal tibia and the distal radius, providing structural bone parameters. Comparing HR-pQCT with MRI, we found that both modalities are capable of offering meaningful information on trabecular structure. Background Magnetic resonance imaging (MRI) has emerged as the leading in vivo method for measuring trabecular bone micro-architecture and providing structural information. Recently, an in vivo HR-pQCT modality was introduced for imaging peripheral sites like the distal tibia and the distal radius, providing structural bone parameters. The goal of this work was to compare and evaluate the performances and in vivo capabilities of HR-pQCT in comparison with MRI at 3 Tesla. Methods To this end images of 8 human specimens (5 tibiae and 3 radii) and 11 participants (6 tibia and 5 radii) were acquired with both modalities. Additionally, the radius specimens were scanned with micro-CT (μCT), which was used as a standard of reference. Structural parameters calculated from MRI were compared with results from HR-pQCT images and additionally μCT for the radii specimens. Results High correlations (r > 0.7) were found for trabecular number and trabecular spacing between the two modalities in vivo and ex vivo. 2D and 3D analysis revealed high correlations (r > 0.8) in structural bone parameters for all measurements. Using micro-CT as standard of reference both results from QCT and MRI correlated well. Conclusion Both imaging modalities were found to perform equally well regarding trabecular bone measurements.
Calcified Tissue International, 2005
The purpose of this study is to use high-resolution magnetic resonance (MR) imaging at 3 Tesla (3T) to quantify trabecular bone structure in vitro using femoral head specimens, and to correlate the calculated structure measures with those that were determined using microcomputed tomography (μCT), the standard of reference. Fifteen cylindrical cores were obtained from fresh femoral heads after total hip arthroplasty. MR images were obtained at 3T using a transmit-receive wrist coil. Highresolution coronal images were acquired using a modified three-dimensional (3D) fast-gradient echo sequence. From these data sets two-dimensional (2D) structural parameters analogous to bone histomorphometry were derived by using both mean intercept length (MIL) methods based on the plate model and the more recent model-assumption free 3D distance-transformation (DT) methods. The parameters measured by the 2D plate model-based MIL method and the DT method included apparent (App). BV/TV (bone volume/total volume), App. Tb.Th (trabecular thickness), App. Tb.Sp (trabecular separation), and App. Tb.N (trabecular number). Identical regions of interest were analyzed in the MR images and the μCT data sets, and similar structure measures were derived. The means and standard deviations of the parameters over all slices were calculated and MR-derived measures were correlated with those derived from the μCT data sets using linear regression analyses. Structure measures were overestimated with MRI, for example, the mean App. BV/TV was 0.45 for MRI and 0.20 for μCT, and the slope of the graph was 1.45. App. Tb.Th was overestimated by a factor of 1.9, whereas App. Tb.Sp was underestimated; Tb.N showed the smallest effect. Correlations between the individual parameters were excellent (App. BV/TV, r 2 = 0.82; App. Tb.Sp, r 2 = 0.84; App. Tb.N, r 2 = 0.81), except for App. Tb.Th (r 2 = 0.67). The results of this study show that trabecular bone structure measures may be obtained using 3T MR imaging. These measures, although higher than the standard of reference, show a highly significant correlation with true structure measures obtained by μCT.
Survey of MRI Usefulness for the Clinical Assessment of Bone Microstructure
International Journal of Molecular Sciences
Bone microarchitecture has been shown to provide useful information regarding the evaluation of skeleton quality with an added value to areal bone mineral density, which can be used for the diagnosis of several bone diseases. Bone mineral density estimated from dual-energy X-ray absorptiometry (DXA) has shown to be a limited tool to identify patients’ risk stratification and therapy delivery. Magnetic resonance imaging (MRI) has been proposed as another technique to assess bone quality and fracture risk by evaluating the bone structure and microarchitecture. To date, MRI is the only completely non-invasive and non-ionizing imaging modality that can assess both cortical and trabecular bone in vivo. In this review article, we reported a survey regarding the clinically relevant information MRI could provide for the assessment of the inner trabecular morphology of different bone segments. The last section will be devoted to the upcoming MRI applications (MR spectroscopy and chemical shi...
Two and three-dimensional morphometric analysis of trabecular bone using X-ray microtomography (µCT)
Revista Brasileira de Engenharia Biomédica, 2014
Introduction: Trabecular bones have a porous microstructure and can be modeled as linear elastic solids, heterogeneous and anisotropic. In the literature, few investigations have compared the two-dimensional (2D) and three-dimensional (3D) morphometric analyses of cancellous bone. Methods: In this investigation eighteen cylindrical samples of cancellous bone (10 mm of diameter and 20 mm of height) were obtained from six bovine head femurs, with similar values for the weight and age, of the same race and gender. The samples were harvested and freezed at-20 °C before carrying out the microCT analysis. The CT-Analyzer software was used to measure in three directions (superior-inferior, lateral-medial and anterior-posterior) parameters such as trabecular thickness, trabecular separation, trabecular number and the eigenvalues of the fabric tensor (M). Results: The Comparison of 2D and 3D analyses for the parameters: 2D (plate model) trabecular thickness, trabecular separation and trabecular number were statistically different (p = 0) showing that measurements are not similar to the 3D ones. However, 2D (rod model) trabecular thickness and 3D trabecular thickness measurements presented no significant difference (p = 0.26). The eigenvalues show that the bovine trabecular microstructure has a tendency to transverserly isotropic symmetry. Discussion: The method proved to be quite interesting for the characterization of the bone structure through 3D measurements of trabecular bone morphometric parameters in the three possible directions of loading. The results show that x-ray microtomography (µCT) is a technique of great potential for characterization and generating bone quality parameters for the diagnosis of bone metabolism diseases.
Analysis of Skeletal Microstructure with Clinical Multislice CT
2006
In view of the great effects of osteoporosis on public health, it would be of great value to be able to measure the three-dimensional structure of trabecular bone in vivo as a means to diagnose and quantify the disease. The aim of this work was to implement a method for quantitative characterisation of trabecular bone structure using clinical CT. Several previously described parameters have been calculated from volumes acquired with a 64-slice clinical scanner. Using automated region growing, distance transforms and three-dimensional thinning, measures describing the number, thickness and spacing of bone trabeculae was obtained. Fifteen bone biopsies were analysed. The results were evaluated using micro-CT as reference. For most parameters studied, the absolute values did not agree well with the reference method, but several parameters were closely correlated with the reference method. The shortcomings appear to be due to the low resolution and high noise level. However, the high correlation found between clinical CT and micro-CT measurements suggest that it might be possible to monitor changes in the trabecular structure in vivo.
Role of Magnetic Resonance for Assessing Structure and Function of Trabecular Bone
2002
The strength of trabecular bone and its resistance to fracture has traditionally been associated with apparent density. This paradigm assumes that neither the ultrastructural nor microstructural make-up of the bone is altered during aging and osteoporosis. There has been growing evidence against this view from both laboratory and clinical studies. Recent advances in noninvasive imaging technology, notably micro-magnetic resonance imaging (µ-MRI), offers an opportunity to test the hypothesis that architecture is an independent contributor to bone strength. Critical hurdles to overcome have their origin in the limited signal-to-noise ratio, which precludes imaging at a voxel size much smaller than trabecular thickness. The resulting partial volume blurring calls for more elaborate processing and analysis techniques. This article reviews new approaches conceived in the authors' laboratory toward acquisition, processing and structural analysis of trabecular bone images in the limited spatial resolution regime of in vivo µ-MRI. The method, termed 'virtual bone biopsy' (VBB), provides detailed insight into the three-dimensional trabecular network topology and scale at the distal radius or distal tibia serving as surrogate sites. The resulting VBB structural parameters are shown to be associated with the bone's biomechanical properties and fracture resistance and the technology has advanced to a stage permitting serial studies in laboratory animals and humans as a means to evaluate the effects of treatment. The method is currently confined to peripheral skeletal sites and its extension to typical fracture sites such as the proximal femur hinges on further advances in detection sensitivity.
Guidelines for assessment of bone microstructure in rodents using micro-computed tomography
Journal of Bone and Mineral Research, 2010
Use of high-resolution micro-computed tomography (mCT) imaging to assess trabecular and cortical bone morphology has grown immensely. There are several commercially available mCT systems, each with different approaches to image acquisition, evaluation, and reporting of outcomes. This lack of consistency makes it difficult to interpret reported results and to compare findings across different studies. This article addresses this critical need for standardized terminology and consistent reporting of parameters related to image acquisition and analysis, and key outcome assessments, particularly with respect to ex vivo analysis of rodent specimens. Thus the guidelines herein provide recommendations regarding (1) standardized terminology and units, (2) information to be included in describing the methods for a given experiment, and (3) a minimal set of outcome variables that should be reported. Whereas the specific research objective will determine the experimental design, these guidelines are intended to ensure accurate and consistent reporting of mCT-derived bone morphometry and density measurements. In particular, the methods section for papers that present mCT-based outcomes must include details of the following scan aspects: (1) image acquisition, including the scanning medium, X-ray tube potential, and voxel size, as well as clear descriptions of the size and location of the volume of interest and the method used to delineate trabecular and cortical bone regions, and (2) image processing, including the algorithms used for image filtration and the approach used for image segmentation. Morphometric analyses should be based on 3D algorithms that do not rely on assumptions about the underlying structure whenever possible. When reporting mCT results, the minimal set of variables that should be used to describe trabecular bone morphometry includes bone volume fraction and trabecular number, thickness, and separation. The minimal set of variables that should be used to describe cortical bone morphometry includes total cross-sectional area, cortical bone area, cortical bone area fraction, and cortical thickness. Other variables also may be appropriate depending on the research question and technical quality of the scan. Standard nomenclature, outlined in this article, should be followed for reporting of results. ß