Role of Magnetic Resonance for Assessing Structure and Function of Trabecular Bone (original) (raw)
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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...
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.
Journal of Bone and Mineral Research, 2010
Micro magnetic resonance imaging (µMRI) is an in vivo imaging method which permits three dimensional (3D) quantification of cortical and trabecular bone microstructure. µMR images can also be used for building microstructural finite element (µFE) models to assess bone stiffness, which highly correlates with bone's resistance to fractures. In order for µMR image-based microstructural and µFE analyses to become standard clinical tools for assessing bone quality, validation with a current gold standard, namely the high-resolution micro computed tomography (µCT) is required. Microstructural measurements of 25 human cadaveric distal tibiae were performed for the registered µMR and µCT images, respectively. Next, whole bone stiffness, trabecular bone stiffness, and elastic moduli of cubic sub-volumes of trabecular bone in both µMR and µCT images were determined by voxel-based µFE analysis. The bone volume fraction (BV/ TV), trabecular number (Tb.N * ), trabecular spacing (Tb.Sp * ), cortical thickness (Ct.Th), and structure model index (SMI) of µMRI showed strong correlations with µCT measurements (r 2 =0.67~0.97), and bone surface to volume ratio (BS/BV), connectivity density (Conn.D), and degree of anisotropy (DA) had significant but moderate correlations (r 2 =0.33~0.51). Each of these measurements also contributed to one or many of the µFE-predicted mechanical properties. However, model-independent trabecular thickness (Tb.Th * ) of µMRI had no correlation with the µCT measurement and did not contribute to any mechanical measurement. Furthermore, the whole bone and trabecular bone stiffness of µMR images were highly correlated to those of µCT images (r 2 =0.86 and 0.96), suggesting that µMRI-based µFE analyses can directly and accurately quantify whole bone mechanical competence. In contrast, the elastic moduli of the µMRI trabecular bone sub-volume had significant but only moderate correlations with their gold standards (r 2 =0.40~0.58). We conclude that most microstructural and mechanical properties of the distal tibia can be efficiently derived from µMR images and can provide additional information regarding bone quality.
Magnetic resonance microscopy of trabecular bone
2002
Background. Bone diseases such as osteoporosis lead to changes in the trabecular bone mass and architecture. Improved methods for the quantitative assessment of trabecular bone are needed to better understand the role of trabecular architecture in bone strength. MR microscopy (MRM), with its ability to achieve resolutions below 50 μm, has proved to be particularly useful for the ex vivo evaluation of the complex architecture of trabecular bone. In this study, we describe the use of projection reconstruction (PR) with MRM for the quantitative evaluation of the three-dimensional structure of trabecular bone explants and for the prediction of their biomechanical properties. Material and methods. High-resolution 3D PR and trabecular bone explants were analysed to determine standard morphologic parameters such as trabecular bone volume fraction (BV/TV or Vv), trabecular thickness (Tb.Th) and trabecular separation (Tb.Sp). Segmentation of the high-resolution images into bone and bone marr...
Novel magnetic resonance technique for characterizing mesoscale structure of trabecular bone
Royal Society open science, 2018
Osteoporosis, characterized by increased fracture risk and bone fragility, impacts millions of adults worldwide, but effective, non-invasive and easily accessible diagnostic tests of the disease remain elusive. We present a magnetic resonance (MR) technique that overcomes the motion limitations of traditional MR imaging to acquire high-resolution frequency-domain data to characterize the texture of biological tissues. This technique does not involve obtaining full two-dimensional or three-dimensional images, but can probe scales down to the order of 40 μm and in particular uncover structural information in trabecular bone. Using micro-computed tomography data of vertebral trabecular bone, we computationally validate this MR technique by simulating MR measurements of a 'ratio metric' determined from a few -space values corresponding to trabecular thickness and spacing. We train a support vector machine classifier on ratio metric values determined from healthy and simulated os...
MRI Techniques for the Examination of Trabecular Bone Structure
Current Medical Imaging Reviews, 2005
It is well known that bone mineral density measurement is a widely available means of identifying individuals with osteoporosis. However, bone strength depends not only on the amount of material but also on properties related to bone quality. Significant progress has been made in the development of magnetic resonance imaging (MRI) techniques for assessing bone status during the past years. This review discusses the technical principles, clinical applications, recent advances, limitations, and future trends of MRI techniques available for the diagnosis of osteoporosis. Using MRI, bone status can be evaluated either by T2* measurements, which are sensitive to field inhomogeneities caused by susceptibility differences at the marrowbone interfaces, or by high-resolution imaging. In T2* relaxometry, the decrease in marrow T2* measurements and its decay characteristics provide useful information about the structure and quality of the trabecular bone. T2* measurements have been performed at several locations of the axial and peripheral skeleton such as spine, proximal femur and calcaneus. It has also been shown that osteoporotic and normal subjects may be distinguished using T2* decay characteristics. In addition to T2* relaxometry, high-resolution MR imaging may be used to quantify trabecular bone architecture. Gradient echo and spin echo sequences have been used to obtain images in vitro and in vivo mainly at peripheral sites of the skeleton. Several image-processing methods have been applied to measure bone structure. Technological advances in MRI scanners offer exciting new possibilities in bone analysis and may contribute to our understanding of osteoporosis.
IEEE Transactions on Biomedical Engineering, 2003
Magnetic resonance (MR) imaging has recently been proposed for assessing osteoporosis and predicting fracture risks. However, accurate acquisition techniques and image analysis protocols for the determination of the trabecular bone structure are yet to be defined. The aim of this study was to assess the potential of projection reconstruction (PR) MR microscopy in the analysis of the three-dimensional (3-D) architecture of trabecular bone and in the prediction of its biomechanical properties. High-resolution 3-D PR images (41 x 41 x 82 microm3 voxels) of 15 porcine trabecular bone explants were analyzed to determine the trabecular bone volume fraction (Vv), the mean trabecular thickness (Tb.Th), and the mean trabecular separation (Tb.Sp) using the method of directed secants. These parameters were then compared with those derived from 3-D conventional spin-echo microimages. In both cases, segmentation of the high-resolution images into bone and bone marrow was obtained using a spatial adaptive threshold. The contemporary inclusion of Vv, Tb.Th and 1/Tb.Sp in a multiple regression analysis significantly improved the prediction of Young's modulus (YM). The parameters derived from the PR spin-echo images were found to be stronger predictors of YM (R2 = 0.94, p = 0.004) than those derived from conventional spin-echo images (R2 = 0.79, p = 0.051). Our study indicates that projection reconstruction MR microscopy appears to be more accurate than the conventional Fourier transform method in the quantification of trabecular bone structure and in the prediction of its bioimechanical properties. The proposed PR approach should be readily adaptable to the in vivo MRI studies of osteoporosis.
2008
Trabecular bone density changes throughout the proximal tibia are indicative of several musculoskeletal disorders of the knee joint. Many of these disorders involve not only changes in the amount of bone, but also in the surrounding soft tissue. Osteoarthritis, for instance, involves bone density changes below the subchondral bone and throughout the proximal tibia, along with degradation evident in the articular cartilage. Osteoporosis, characterized by low bone density may also involve changes in bone size, structure or microarchitecture, each of which may contribute to fracture risk. Recent studies have shown that magnetic resonance (MR) imaging, most frequently applied for soft tissue imaging, also allows non-invasive 3dimensional characterization of bone microstructure. The purpose of the current study is to use whole joint MR images to acquire regional apparent bone volume fraction (appBVF) throughout the proximal tibia and correlate with mechanical properties measured on the corresponding ex vivo specimens. To compare our method to a high-resolution imaging modality, micro-CT analysis was performed in a subset of specimens. Using linear mixed-effects models, significant correlations (p b 0.05) were determined between MR appBVF and Young's modulus (r 2 = 0.58, MPSE = 3633 MPa 2), yield stress (r 2 = 0.73, MPSE = 1.53 MPa 2) and ultimate stress (r 2 = 0.72, MPSE = 2.29 MPa 2). Comparable significant correlations (p b 0.05) were also determined between micro-CT BVF and Young's modulus (r 2 = 0.47, MPSE = 5179 MPa 2), yield stress (r 2 = 0.80, MPSE = 1.23 MPa 2) and ultimate stress (r 2 = 0.83, MPSE = 1.76 MPa 2). The current study demonstrates that MR imaging may be used as an in vivo imaging tool to determine differences in bone strength between subjects and regional variations within a single tibia.
Calcified tissue international, 2014
The utility of HR-CT to study longitudinal changes in bone microarchitecture is limited by subject radiation exposure. Although MR is not subject to this limitation, it is limited both by patient movement that occurs during prolonged scanning at distal sites, and by the signal-to-noise ratio that is achievable for high-resolution images in a reasonable scan time at proximal sites. Recently, a novel MR-based technique, fine structure analysis (FSA) (Chase et al. Localised one-dimensional magnetic resonance spatial frequency spectroscopy. PCT/US2012/068284 2012, James and Chase Magnetic field gradient structure characteristic assessment using one-dimensional (1D) spatial frequency distribution analysis. 7932720 B2, 2011) has been developed which provides both high-resolution and fast scan times, but which generates at a designated set of spatial positions (voxels) a one-dimensional signal of spatial frequencies. Appendix 1 provides a brief introduction to FSA. This article describes a...