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Gosset A, Pouillès JM, Trémollieres F. Menopausal hormone therapy for the management of osteoporosis. Best Pract Res Clin Endocrinol Metab 2021; 35:101551. [PMID: 34119418 DOI: 10.1016/j.beem.2021.101551] [Citation(s) in RCA: 52] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Postmenopausal osteoporosis is a frequent clinical condition which affects nearly 1 in 3 women. Estrogen deficiency leads to rapid bone loss which is maximal within the first 2-3 years after the menopause transition and can be prevented by menopause hormone therapy (MHT). Not only, MHT prevents bone loss and the degradation of the bone microarchitecture but it significantly reduces the risk of fracture at all bone sites by 20-40%. It is the only anti-osteoporotic therapy that has a proven efficacy regardless of basal level of risk, even in low-risk women for fracture. Following the publication of the WHI results, use of MHT has considerably declined due to safety concerns which raise the question as to whether it might still be used in the prevention of osteoporosis. Over the last years, subsequent re-analyses of the WHI and further trials have challenged the initial conclusions of the WHI. It is now clearer that the individual benefit-risk balance of MHT is dependent on the individual risk profile in each woman as well as whether estrogen is opposed or unopposed, the type of estrogens and progestogens or doses and routes of administration. It must be also reminded that to date osteoporosis is a chronic disease that cannot be cured. The choice of the 1st treatment option should thus always be made in the context of a more comprehensive long-term strategy. This is particular true in early postmenopausal women found to be at low/moderate risk of fragility fracture over the first 10 years after menopause but who may have a much greater lifetime risk. In the absence of contraindication, use of MHT should be considered as a 1st option for the maintenance of bone health in those women where specific bone active medications are not warranted. Subsequent reassessment of the individual benefit-risk balance of MHT is thereafter recommended, with the possibility of switching to another osteoporosis treatment if the balance is not considered as favourable as at the beginning of the menopause for women still at high risk of fracture.
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Affiliation(s)
- Anna Gosset
- Centre de Ménopause et Maladies Osseuses Métaboliques, Hôpital Paule de Viguier, 330 Avenue de Grande-Bretagne, TSA 70034, 31059, Toulouse, France
| | - Jean-Michel Pouillès
- Centre de Ménopause et Maladies Osseuses Métaboliques, Hôpital Paule de Viguier, 330 Avenue de Grande-Bretagne, TSA 70034, 31059, Toulouse, France
| | - Florence Trémollieres
- Centre de Ménopause et Maladies Osseuses Métaboliques, Hôpital Paule de Viguier, 330 Avenue de Grande-Bretagne, TSA 70034, 31059, Toulouse, France; INSERM U1048-I2MC-Equipe 9, Université Toulouse III Paul Sabatier, 1 Avenue du Professeur Jean Poulhès, BP 84225, 31432, Toulouse Cedex 4, France.
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Pouillès JM, Gosset A, Trémollieres F. [Menopause, menopause hormone therapy and osteoporosis. Postmenopausal women management: CNGOF and GEMVi clinical practice guidelines]. GYNECOLOGIE, OBSTETRIQUE, FERTILITE & SENOLOGIE 2021; 49:420-437. [PMID: 33753297 DOI: 10.1016/j.gofs.2021.03.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Postmenopausal osteoporosis is a frequent clinical condition, which affects nearly 1 in 3 women. Estrogen deficiency leads to rapid bone loss, which is maximal within the first years after the menopause transition and can be prevented by menopause hormone therapy (MHT). Assessment of the individual risk of osteoporosis is primarily based on the measurement of bone mineral density (BMD) at the spine and femur by DXA. Clinical risk factors (CRFs) for fractures taken either alone or in combination in the FRAX score were shown not to reliably predict fractures and/or osteoporosis (as defined by a T-score<-2.5) in early postmenopausal women. If DXA measurement is indicated in all women with CRFs for fractures, it can be proposed on a case-by-case basis, when knowledge of BMD is likely to condition the management of women at the beginning of menopause, particularly the benefit-risk balance of MHT. MHT prevents both bone loss and degradation of the bone microarchitecture in early menopause. It significantly reduces the risk of fracture at all bone sites by 20 to 40% regardless of basal level of risk with an estrogen-dependent dose-effect. Given the inter-individual variability in bone response, individual monitoring of the bone effect of MHT is warranted when prescribed for the prevention of osteoporosis. This monitoring is based on repeated measurement of lumbar and femoral BMD (on the same DXA measurement system) after 2years of MHT, the response criterion being no significant bone loss. Discontinuation of treatment is associated with a resumption of transient bone loss although there is a large variability in the rate of bone loss among women. Basically, there is a return to the level of fracture risk comparable to that of in untreated woman of the same age within 2 to 5years. Therefore, when MHT is prescribed for the prevention of osteoporosis in women with an increased risk at the beginning of menopause, measurement of BMD is recommended when MHT is stopped in order to consider further management of the risk of fracture whenever necessary (with possibly another anti-osteoporotic treatment).
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Affiliation(s)
- J-M Pouillès
- Centre de ménopause et maladies osseuses métaboliques, hôpital Paule-de-Viguier, CHU Toulouse, 330, avenue de Grande-Bretagne, TSA 70034, 31059 Toulouse, France
| | - A Gosset
- Centre de ménopause et maladies osseuses métaboliques, hôpital Paule-de-Viguier, CHU Toulouse, 330, avenue de Grande-Bretagne, TSA 70034, 31059 Toulouse, France
| | - F Trémollieres
- Centre de ménopause et maladies osseuses métaboliques, hôpital Paule-de-Viguier, CHU Toulouse, 330, avenue de Grande-Bretagne, TSA 70034, 31059 Toulouse, France; INSERM U1048, I2MC, équipe 9, université Toulouse III Paul-Sabatier, 1, avenue du Professeur-Jean-Poulhès, BP 84225, 31432 Toulouse cedex 4, France.
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Soldati E, Rossi F, Vicente J, Guenoun D, Pithioux M, Iotti S, Malucelli E, Bendahan D. Survey of MRI Usefulness for the Clinical Assessment of Bone Microstructure. Int J Mol Sci 2021; 22:2509. [PMID: 33801539 PMCID: PMC7958958 DOI: 10.3390/ijms22052509] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Revised: 02/21/2021] [Accepted: 02/25/2021] [Indexed: 12/12/2022] Open
Abstract
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 shift encoding MRI, solid state MRI and quantitative susceptibility mapping), which could provide additional biomarkers for the assessment of bone microarchitecture.
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Affiliation(s)
- Enrico Soldati
- CRMBM, CNRS, Aix Marseille University, 13385 Marseille, France;
- IUSTI, CNRS, Aix Marseille University, 13013 Marseille, France;
- ISM, CNRS, Aix Marseille University, 13288 Marseille, France; (D.G.); (M.P.)
| | - Francesca Rossi
- Department of Pharmacy and Biotechnology, University of Bologna, 40126 Bologna, Italy; (F.R.); (S.I.); (E.M.)
| | - Jerome Vicente
- IUSTI, CNRS, Aix Marseille University, 13013 Marseille, France;
| | - Daphne Guenoun
- ISM, CNRS, Aix Marseille University, 13288 Marseille, France; (D.G.); (M.P.)
- Department of Radiology, Institute for Locomotion, Saint-Marguerite Hospital, ISM, CNRS, APHM, Aix Marseille University, 13274 Marseille, France
| | - Martine Pithioux
- ISM, CNRS, Aix Marseille University, 13288 Marseille, France; (D.G.); (M.P.)
- Department of Orthopedics and Traumatology, Institute for Locomotion, Saint-Marguerite Hospital, ISM, CNRS, APHM, Aix Marseille University, 13274 Marseille, France
| | - Stefano Iotti
- Department of Pharmacy and Biotechnology, University of Bologna, 40126 Bologna, Italy; (F.R.); (S.I.); (E.M.)
- National Institute of Biostructures and Biosystems, 00136 Rome, Italy
| | - Emil Malucelli
- Department of Pharmacy and Biotechnology, University of Bologna, 40126 Bologna, Italy; (F.R.); (S.I.); (E.M.)
| | - David Bendahan
- CRMBM, CNRS, Aix Marseille University, 13385 Marseille, France;
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Guha I, Nadeem SA, You C, Zhang X, Levy SM, Wang G, Torner JC, Saha PK. Deep Learning Based High-Resolution Reconstruction of Trabecular Bone Microstructures from Low-Resolution CT Scans using GAN-CIRCLE. PROCEEDINGS OF SPIE--THE INTERNATIONAL SOCIETY FOR OPTICAL ENGINEERING 2020; 11317:113170U. [PMID: 32201450 PMCID: PMC7085412 DOI: 10.1117/12.2549318] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Osteoporosis is a common age-related disease characterized by reduced bone density and increased fracture-risk. Microstructural quality of trabecular bone (Tb), commonly found at axial skeletal sites and at the end of long bones, is an important determinant of bone-strength and fracture-risk. High-resolution emerging CT scanners enable in vivo measurement of Tb microstructures at peripheral sites. However, resolution-dependence of microstructural measures and wide resolution-discrepancies among various CT scanners together with rapid upgrades in technology warrant data harmonization in CT-based cross-sectional and longitudinal bone studies. This paper presents a deep learning-based method for high-resolution reconstruction of Tb microstructures from low-resolution CT scans using GAN-CIRCLE. A network was developed and evaluated using post-registered ankle CT scans of nineteen volunteers on both low- and high-resolution CT scanners. 9,000 matching pairs of low- and high-resolution patches of size 64×64 were randomly harvested from ten volunteers for training and validation. Another 5,000 matching pairs of patches from nine other volunteers were used for evaluation. Quantitative comparison shows that predicted high-resolution scans have significantly improved structural similarity index (p < 0.01) with true high-resolution scans as compared to the same metric for low-resolution data. Different Tb microstructural measures such as thickness, spacing, and network area density are also computed from low- and predicted high-resolution images, and compared with the values derived from true high-resolution scans. Thickness and network area measures from predicted images showed higher agreement with true high-resolution CT (CCC = [0.95, 0.91]) derived values than the same measures from low-resolution images (CCC = [0.72, 0.88]).
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Affiliation(s)
- Indranil Guha
- Department of Electrical and Computer Engineering, College of Engineering, University of Iowa, Iowa City, IA 52242
| | - Syed Ahmed Nadeem
- Department of Electrical and Computer Engineering, College of Engineering, University of Iowa, Iowa City, IA 52242
| | - Chenyu You
- Department of Computer Science, Yale University, New Haven, CT 05620
| | - Xiaoliu Zhang
- Department of Electrical and Computer Engineering, College of Engineering, University of Iowa, Iowa City, IA 52242
| | - Steven M Levy
- Department of Preventive and Community Dentistry, College of Dentistry, University of Iowa, Iowa City, IA 52242
| | - Ge Wang
- Biomedical Imaging Center, BME/CBIS, Rensselaer Polytechnic Institute, Troy, New York, NY 12180
| | - James C Torner
- Department of Epidemiology, University of Iowa, Iowa City, IA 52242
| | - Punam K Saha
- Department of Electrical and Computer Engineering, College of Engineering, University of Iowa, Iowa City, IA 52242
- Department of Radiology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242
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Zhang X, Letuchy EM, Levy SM, Torner JC, Saha PK. CT-Based Characterization of Transverse and Longitudinal Trabeculae and Its Applications. PROCEEDINGS OF SPIE--THE INTERNATIONAL SOCIETY FOR OPTICAL ENGINEERING 2020; 11317:113171F. [PMID: 32201451 PMCID: PMC7085413 DOI: 10.1117/12.2549881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Osteoporosis is a common age-related disease characterized by reduced bone mineral density (BMD), micro-structural deterioration, and enhanced fracture-risk. Although, BMD is clinically used to define osteoporosis, there are compelling evidences that bone micro-structural properties are strong determinants of bone strength and fracture-risk. Reliable measures of effective trabecular bone (Tb) micro-structural features are of paramount clinical significance. Tb consists of transverse and longitudinal micro-structures, and there is a hypothesis that transverse trabeculae improve bone strength by arresting buckling of longitudinal trabeculae. In this paper, we present an emerging clinical CT-based new method for characterizing transverse and longitudinal trabeculae, validate the method, and examine its application in human studies. Specifically, we examine repeat CT scan reproducibility, and evaluate the relationships of these measures with gender and body size using human CT data from the Iowa Bone Development Study (IBDS) (n = 99; 49 female). Based on a cadaveric ankle study (n = 12), both transverse and longitudinal Tb measures are found reproducible (ICC > 0.94). It was observed in the IBDS human data that males have significantly higher trabecular bone measures than females for both inner (p < 0.05) and outer (p < 0.01) regions of interest (ROIs). For weight, Spearman correlations ranged 0.43-0.48 for inner ROI measures and 0.50-0.52 for outer ROI measures for females versus 0.30-0.34 and 0.23-0.25 for males. Correlation with height was lower (0.36-0.39), but still mostly significant for females. No association of trabecular measures with height was found for males.
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Affiliation(s)
- Xiaoliu Zhang
- Department of Electrical and Computer Engineering, University of Iowa, USA
| | | | - Steven M Levy
- Department of Preventive and Community Dentistry, University of Iowa, USA
| | | | - Punam K Saha
- Department of Electrical and Computer Engineering, University of Iowa, USA
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Deniz CM, Xiang S, Hallyburton RS, Welbeck A, Babb JS, Honig S, Cho K, Chang G. Segmentation of the Proximal Femur from MR Images using Deep Convolutional Neural Networks. Sci Rep 2018; 8:16485. [PMID: 30405145 PMCID: PMC6220200 DOI: 10.1038/s41598-018-34817-6] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Accepted: 10/26/2018] [Indexed: 11/20/2022] Open
Abstract
Magnetic resonance imaging (MRI) has been proposed as a complimentary method to measure bone quality and assess fracture risk. However, manual segmentation of MR images of bone is time-consuming, limiting the use of MRI measurements in the clinical practice. The purpose of this paper is to present an automatic proximal femur segmentation method that is based on deep convolutional neural networks (CNNs). This study had institutional review board approval and written informed consent was obtained from all subjects. A dataset of volumetric structural MR images of the proximal femur from 86 subjects were manually-segmented by an expert. We performed experiments by training two different CNN architectures with multiple number of initial feature maps, layers and dilation rates, and tested their segmentation performance against the gold standard of manual segmentations using four-fold cross-validation. Automatic segmentation of the proximal femur using CNNs achieved a high dice similarity score of 0.95 ± 0.02 with precision = 0.95 ± 0.02, and recall = 0.95 ± 0.03. The high segmentation accuracy provided by CNNs has the potential to help bring the use of structural MRI measurements of bone quality into clinical practice for management of osteoporosis.
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Affiliation(s)
- Cem M Deniz
- Department of Radiology, New York University School of Medicine, New York, NY, 10016, USA.
- Bernard and Irene Schwartz Center for Biomedical Imaging, New York University School of Medicine, New York, NY, 10016, USA.
| | - Siyuan Xiang
- Center for Data Science, New York University, New York, NY, 10012, USA
| | | | - Arakua Welbeck
- Bernard and Irene Schwartz Center for Biomedical Imaging, New York University School of Medicine, New York, NY, 10016, USA
| | - James S Babb
- Bernard and Irene Schwartz Center for Biomedical Imaging, New York University School of Medicine, New York, NY, 10016, USA
| | - Stephen Honig
- Osteoporosis Center, Hospital for Joint Diseases, New York University Langone Medical Center, New York, NY, 10003, USA
| | - Kyunghyun Cho
- Center for Data Science, New York University, New York, NY, 10012, USA
- Courant Institute of Mathematical Science, New York University, New York, NY, 10012, USA
| | - Gregory Chang
- Department of Radiology, New York University School of Medicine, New York, NY, 10016, USA
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Ben Kahla R, Barkaoui A, Merzouki T. Age-related mechanical strength evolution of trabecular bone under fatigue damage for both genders: Fracture risk evaluation. J Mech Behav Biomed Mater 2018; 84:64-73. [PMID: 29751273 DOI: 10.1016/j.jmbbm.2018.05.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2017] [Revised: 07/23/2017] [Accepted: 05/03/2018] [Indexed: 12/11/2022]
Abstract
Bone tissue is a living composite material, providing mechanical and homeostatic functions, and able to constantly adapt its microstructure to changes in long term loading. This adaptation is conducted by a physiological process, known as "bone remodeling". This latter is manifested by interactions between osteoclasts and osteoblasts, and can be influenced by many local factors, via effects on bone cell differentiation and proliferation. In the current work, age and gender effects on damage rate evolution, throughout life, have been investigated using a mechanobiological finite element modeling. To achieve the aim, a mathematical model has been developed, coupling both cell activities and mechanical behavior of trabecular bone, under cyclic loadings. A series of computational simulations (ABAQUS/UMAT) has been performed on a 3D human proximal femur, allowing to investigate the effects of mechanical and biological parameters on mechanical strength of trabecular bone, in order to evaluate the fracture risk resulting from fatigue damage. The obtained results revealed that mechanical stimulus amplitude affects bone resorption and formation rates, and indicated that age and gender are major factors in bone response to the applied loadings.
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Affiliation(s)
- Rabeb Ben Kahla
- Laboratoire de Systèmes et de Mécanique Appliquée (Lasmap-EPT), Ecole Polytechnique de Tunis, Université de Carthage, 2078 La Marsa, Tunisia
| | - Abdelwahed Barkaoui
- Laboratoire de Mécanique Appliquée et Ingénierie (LR-MAI), LR-ES19, Ecole Nationale d'Ingénieurs de Tunis, Université de Tunis El Manar, 1002 Tunis, Tunisa; Laboratoire des Energies Renouvelables et Matériaux Avancés (LERMA), Ecole Supérieure de l'Ingénierie de l'Energie,Université Internationale de Rabat, Rocade Rabat-Salé, 11100, Rabat-Sala El Jadida, Morocco.
| | - Tarek Merzouki
- Laboratoire Ingénierie des Systèmes de Versailles, Université de Versailles St Quentin en Yvelines, 10 avenue de l'Europe, 78140 Velizy, France
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Effect of the different implant protocols on peri-implant bone: a 6-month prospective study in beagle dogs. Int J Artif Organs 2017; 40:701-708. [PMID: 28862720 DOI: 10.5301/ijao.5000637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/10/2017] [Indexed: 02/05/2023]
Abstract
OBJECTIVE To compare the effects of different implant placement and loading protocols on the marginal bone loss (MBL) in beagles by intraoral radiography. METHODS AND MATERIALS 61 dental implants were inserted on 9 beagle dogs at bilateral lower posteriors according to 8 different protocols: immediate implant placement and immediate loading for 3 months (IIP + IL3) or 6 months (IIP + IL6) and unloading (IIP + UL), immediate implant placement and delayed loading for 3 months (IIP + DL3) or 6 months (IIP + DL6), delayed implant placement and immediate loading for 3 months (DIP + IL3) or delayed loading for 3 months (DIP + DL3) and unloading (DIP + UL). Intraoral radiography was performed to analyze the MBL during each surgery, before and after the implant placement and at 3-month intervals after the procedure. RESULTS In total, 57 samples were included. There was less MBL (p<0.05) in the IIP + IL3 group (1.22 ± 0.63 mm) compared to the DIP + IL3 group (1.89 ± 0.9 mm). The longer the loading time, the more bone loss appeared in the IIP + IL group; however, the results were reversed in the IIP + DL group. The MBL during the latter 3-month period was dramatically decreased compared to the former 3-month period in the IIP + DL3 group (p<0.05). CONCLUSIONS The IIP + IL group seems superior to the DL protocol and the MBL changed significantly during the first three months and thereafter became stable.
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Chang G, Boone S, Martel D, Rajapakse CS, Hallyburton RS, Valko M, Honig S, Regatte RR. MRI assessment of bone structure and microarchitecture. J Magn Reson Imaging 2017; 46:323-337. [PMID: 28165650 PMCID: PMC5690546 DOI: 10.1002/jmri.25647] [Citation(s) in RCA: 77] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Accepted: 12/21/2016] [Indexed: 12/12/2022] Open
Abstract
Osteoporosis is a disease of weak bone and increased fracture risk caused by low bone mass and microarchitectural deterioration of bone tissue. The standard-of-care test used to diagnose osteoporosis, dual-energy x-ray absorptiometry (DXA) estimation of areal bone mineral density (BMD), has limitations as a tool to identify patients at risk for fracture and as a tool to monitor therapy response. Magnetic resonance imaging (MRI) assessment of bone structure and microarchitecture has been proposed as another method to assess bone quality and fracture risk in vivo. MRI is advantageous because it is noninvasive, does not require ionizing radiation, and can evaluate both cortical and trabecular bone. In this review article, we summarize and discuss research progress on MRI of bone structure and microarchitecture over the last decade, focusing on in vivo translational studies. Single-center, in vivo studies have provided some evidence for the added value of MRI as a biomarker of fracture risk or treatment response. Larger, prospective, multicenter studies are needed in the future to validate the results of these initial translational studies. LEVEL OF EVIDENCE 5 Technical Efficacy: Stage 5 J. MAGN. RESON. IMAGING 2017;46:323-337.
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Affiliation(s)
- Gregory Chang
- Department of Radiology, Center for Biomedical Imaging, NYU Langone Medical Center, New York, New York, USA
| | - Sean Boone
- Department of Radiology, Center for Biomedical Imaging, NYU Langone Medical Center, New York, New York, USA
| | - Dimitri Martel
- Department of Radiology, Center for Biomedical Imaging, NYU Langone Medical Center, New York, New York, USA
| | - Chamith S Rajapakse
- Department of Radiology, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Robert S Hallyburton
- Department of Radiology, Center for Biomedical Imaging, NYU Langone Medical Center, New York, New York, USA
| | - Mitch Valko
- Department of Radiology, Center for Biomedical Imaging, NYU Langone Medical Center, New York, New York, USA
| | - Stephen Honig
- Osteoporosis Center, Hospital for Joint Diseases, NYU Langone Medical Center, New York, New York, USA
| | - Ravinder R Regatte
- Department of Radiology, Center for Biomedical Imaging, NYU Langone Medical Center, New York, New York, USA
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Pfister AK, Welch CA, John M, Emmett MK. Changes in Nonosteoporotic Bone Density and Subsequent Fractures in Women. South Med J 2016; 109:118-23. [PMID: 26840970 DOI: 10.14423/smj.0000000000000410] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
OBJECTIVES Osteopenia is considerably more common than osteoporosis and accounts for most of the fracture burden in women older than 50 years. It is uncertain when to initiate treatment in osteopenia. We sought to determine in women with osteopenia what effect transitioning to lower categories had on subsequent fracturing. METHODS We surveyed 1150 women from office-based practices who had initial normal or osteopenic bone mineral densities (BMDs) and who were retested after 5.75 years. We classified categories related to baseline T scores as follows: normal (>-1.0), mild osteopenia (-1.0 to -1.49), moderate osteopenia (-1.5 to -1.99), and severe osteopenia (-2.0 to -2.49). We determined during a 9.6-year follow-up period the fracture occurrence in those who maintained their initial category status or transitioned into lower categories. RESULTS Transitioning to lower categories was not significantly different among baseline osteopenic categories but significantly more than normal baseline BMDs. Total fractures, individuals fracturing, and major fractures were significantly more, with baseline T scores of ≤-1.5 (<0.001). Although only 10.2% transitioned to osteoporosis, 90.5% of these transitions occurred with baseline T scores ≤-1.5 and accounted for significantly more fractures than baseline T scores of >-1.5. CONCLUSIONS Most subsequent fractures and transitions to osteoporosis occurred with baseline T scores ≤-1.5. Clinical risk factors need to be used to determine at what T score threshold treatment would be cost effective.
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Affiliation(s)
- Alfred K Pfister
- From the Department of Medicine, West Virginia School of Medicine, Charleston, and the Department of Health Services and Outcomes Research, Charleston Area Medical Center Health Education and Research Institute, Charleston, West Virginia
| | - Christine A Welch
- From the Department of Medicine, West Virginia School of Medicine, Charleston, and the Department of Health Services and Outcomes Research, Charleston Area Medical Center Health Education and Research Institute, Charleston, West Virginia
| | - Molly John
- From the Department of Medicine, West Virginia School of Medicine, Charleston, and the Department of Health Services and Outcomes Research, Charleston Area Medical Center Health Education and Research Institute, Charleston, West Virginia
| | - Mary K Emmett
- From the Department of Medicine, West Virginia School of Medicine, Charleston, and the Department of Health Services and Outcomes Research, Charleston Area Medical Center Health Education and Research Institute, Charleston, West Virginia
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12
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Saha PK, Strand R, Borgefors G. Digital Topology and Geometry in Medical Imaging: A Survey. IEEE TRANSACTIONS ON MEDICAL IMAGING 2015; 34:1940-1964. [PMID: 25879908 DOI: 10.1109/tmi.2015.2417112] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Digital topology and geometry refers to the use of topologic and geometric properties and features for images defined in digital grids. Such methods have been widely used in many medical imaging applications, including image segmentation, visualization, manipulation, interpolation, registration, surface-tracking, object representation, correction, quantitative morphometry etc. Digital topology and geometry play important roles in medical imaging research by enriching the scope of target outcomes and by adding strong theoretical foundations with enhanced stability, fidelity, and efficiency. This paper presents a comprehensive yet compact survey on results, principles, and insights of methods related to digital topology and geometry with strong emphasis on understanding their roles in various medical imaging applications. Specifically, this paper reviews methods related to distance analysis and path propagation, connectivity, surface-tracking, image segmentation, boundary and centerline detection, topology preservation and local topological properties, skeletonization, and object representation, correction, and quantitative morphometry. A common thread among the topics reviewed in this paper is that their theory and algorithms use the principle of digital path connectivity, path propagation, and neighborhood analysis.
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13
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Bae WC, Patil S, Biswas R, Li S, Chang EY, Statum S, D'Lima DD, Chung CB, Du J. Magnetic resonance imaging assessed cortical porosity is highly correlated with μCT porosity. Bone 2014; 66:56-61. [PMID: 24928498 PMCID: PMC4125420 DOI: 10.1016/j.bone.2014.06.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Revised: 05/29/2014] [Accepted: 06/02/2014] [Indexed: 12/29/2022]
Abstract
Cortical bone is typically regarded as "MR invisible" with conventional clinical magnetic resonance imaging (MRI) pulse sequences. However, recent studies have demonstrated that free water in the microscopic pores of cortical bone has a short T2* but a relatively long T2, and may be detectable with conventional clinical spin echo (SE) or fast spin echo (FSE) sequences. In this study we describe the use of a conventional two-dimensional (2D) FSE sequence to assess cortical bone microstructure and measure cortical porosity using a clinical 3T scanner. Twelve cadaveric human cortical bone samples were studied with MRI and microcomputed tomography (μCT) (downsampled to the same spatial resolution). Preliminary results show that FSE-determined porosity is highly correlated (R(2)=0.83; P<0.0001) with μCT porosity. Bland-Altman analysis suggested a good agreement between FSE and μCT with tight limit of agreement at around 3%. There is also a small bias of -2% for the FSE data, which suggested that the FSE approach slightly underestimated μCT porosity. The results demonstrate that cortical porosity can be directly assessed using conventional clinical FSE sequences. The clinical feasibility of this approach was also demonstrated on six healthy volunteers using 2D FSE sequences as well as 2D ultrashort echo time (UTE) sequences with a minimal echo time (TE) of 8μs, which provide high contrast imaging of cortical bone in vivo.
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Affiliation(s)
- Won C Bae
- Department of Radiology, University of California, San Diego, CA, USA; Department of Radiology, VA San Diego Healthcare System, La Jolla, CA, USA
| | - Shantanu Patil
- Shiley Center for Orthopaedic Research & Education, Scripps Clinic, La Jolla, CA, USA
| | - Reni Biswas
- Department of Radiology, University of California, San Diego, CA, USA
| | - Shihong Li
- Department of Radiology, University of California, San Diego, CA, USA; Department of Radiology, Hua Dong Hospital, Fudan University, Shanghai, PR China
| | - Eric Y Chang
- Department of Radiology, VA San Diego Healthcare System, La Jolla, CA, USA; Department of Radiology, University of California, San Diego, CA, USA
| | - Sheronda Statum
- Department of Radiology, University of California, San Diego, CA, USA; Department of Radiology, VA San Diego Healthcare System, La Jolla, CA, USA
| | - Darryl D D'Lima
- Shiley Center for Orthopaedic Research & Education, Scripps Clinic, La Jolla, CA, USA
| | - Christine B Chung
- Department of Radiology, VA San Diego Healthcare System, La Jolla, CA, USA; Department of Radiology, University of California, San Diego, CA, USA
| | - Jiang Du
- Department of Radiology, University of California, San Diego, CA, USA; Department of Radiology, VA San Diego Healthcare System, La Jolla, CA, USA.
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Al Mukaddam M, Rajapakse CS, Bhagat YA, Wehrli FW, Guo W, Peachey H, LeBeau SO, Zemel BS, Wang C, Swerdloff RS, Kapoor SC, Snyder PJ. Effects of testosterone and growth hormone on the structural and mechanical properties of bone by micro-MRI in the distal tibia of men with hypopituitarism. J Clin Endocrinol Metab 2014; 99:1236-44. [PMID: 24423356 PMCID: PMC3973782 DOI: 10.1210/jc.2013-3665] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Severe deficiencies of testosterone (T) and GH are associated with low bone mineral density (BMD) and increased fracture risk. Replacement of T in hypogonadal men improves several bone parameters. Replacement of GH in GH-deficient men improves BMD. OBJECTIVE Our objective was to determine whether T and GH treatment together improves the structural and mechanical parameters of bone more than T alone in men with hypopituitarism. DESIGN AND SUBJECTS This randomized, prospective, 2-year study included 32 men with severe deficiencies of T and GH due to panhypopituitarism. INTERVENTION Subjects were randomized to receive T alone (n = 15) or T and GH (n = 17) for 2 years. MAIN OUTCOME MEASURES We evaluated magnetic resonance microimaging-derived structural (bone volume fraction [BVF] and trabecular thickness) and mechanical (axial stiffness [AS], a measure of bone strength) properties of the distal tibia at baseline and after 1 and 2 years of treatment. RESULTS Treatment with T and GH did not affect BVF, thickness, or AS differently from T alone. T treatment in all subjects for 2 years increased trabecular BVF by 9.6% (P < .0001), trabecular thickness by 2.6% (P < .001), and trabecular AS by 9.8% (P < .001). In contrast, testosterone treatment in all subjects significantly increased cortical thickness by 2.4% (P < .01) but decreased cortical BVF by -4.7% (P < .01) and cortical AS by -6.9% (P < .01). CONCLUSION Combined T and GH treatment of men with hypopituitarism for 2 years did not improve the measured structural or mechanical parameters of the distal tibia more than T alone. However, testosterone significantly increased the structural and mechanical properties of trabecular bone but decreased most of these properties of cortical bone, illustrating the potential importance of assessing trabecular and cortical bone separately in future studies of the effect of testosterone on bone.
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Affiliation(s)
- Mona Al Mukaddam
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine (M.A.M., H.P., S.O.L., P.J.S.); Laboratory of Structural NMR Imaging, Department of Radiology (C.S.R., Y.A.B., F.W.W.), Department of Biostatistics and Epidemiology (W.G.), and the Clinical and Translational Research Center (S.C.K.), Raymond and Ruth Perelman School of Medicine, University of Pennsylvania; and the Division of Gastroenterology, Hepatology, and Nutrition (B.S.Z.), The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania 19104; and Division of Endocrinology and Metabolism (C.W., R.S.S.), Harbor-University of California at Los Angeles Medical Center and Los Angeles Biomedical Research Institute, Torrance, California 90509
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15
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Rajapakse CS, Phillips EA, Sun W, Wald MJ, Magland JF, Snyder PJ, Wehrli FW. Vertebral deformities and fractures are associated with MRI and pQCT measures obtained at the distal tibia and radius of postmenopausal women. Osteoporos Int 2014; 25:973-82. [PMID: 24221453 PMCID: PMC4746757 DOI: 10.1007/s00198-013-2569-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Accepted: 10/24/2013] [Indexed: 11/26/2022]
Abstract
SUMMARY We investigated the association of postmenopausal vertebral deformities and fractures with bone parameters derived from distal extremities using MRI and pQCT. Distal extremity measures showed variable degrees of association with vertebral deformities and fractures, highlighting the systemic nature of postmenopausal bone loss. INTRODUCTION Prevalent vertebral deformities and fractures are known to predict incident further fractures. However, the association of distal extremity measures and vertebral deformities in postmenopausal women has not been fully established. METHODS This study involved 98 postmenopausal women (age range 60-88 years, mean 70 years) with DXA BMD T-scores at either the hip or spine in the range of -1.5 to -3.5. Wedge, biconcavity, and crush deformities were computed on the basis of spine MRI. Vertebral fractures were assessed using Eastell's criterion. Distal tibia and radius stiffness was computed using MRI-based finite element analysis. BMD at the distal extremities were obtained using pQCT. RESULTS Several distal extremity MRI and pQCT measures showed negative association with vertebral deformity on the basis of single parameter correlation (r up to 0.67) and two-parameter regression (r up to 0.76) models involving MRI stiffness and pQCT BMD. Subjects who had at least one prevalent vertebral fracture showed decreased MRI stiffness (up to 17.9 %) and pQCT density (up to 34.2 %) at the distal extremities compared to the non-fracture group. DXA lumbar spine BMD T-score was not associated with vertebral deformities. CONCLUSIONS The association between vertebral deformities and distal extremity measures supports the notion of postmenopausal osteoporosis as a systemic phenomenon.
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Affiliation(s)
- C S Rajapakse
- University of Pennsylvania School of Medicine, Philadelphia, PA, USA,
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16
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Rajapakse CS, Chang G. Impact of body habitus on radiologic interpretations. Acad Radiol 2014; 21:1-2. [PMID: 24331258 DOI: 10.1016/j.acra.2013.10.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2013] [Revised: 09/10/2013] [Accepted: 10/04/2013] [Indexed: 01/25/2023]
Affiliation(s)
- Chamith S Rajapakse
- Department of Radiology, University of Pennsylvania School of Medicine, 253 S 45th St., Philadelphia, PA 19104.
| | - Gregory Chang
- Department of Radiology, New York University Langone Medical Center, NY
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18
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Harrar K, Hamami L, Lespessailles E, Jennane R. Piecewise Whittle estimator for trabecular bone radiograph characterization. Biomed Signal Process Control 2013. [DOI: 10.1016/j.bspc.2013.06.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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19
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Huang Y, Van Dessel J, Liang X, Depypere M, Zhong W, Ma G, Lambrichts I, Maes F, Jacobs R. Effects of immediate and delayed loading on peri-implant trabecular structures: a cone beam CT evaluation. Clin Implant Dent Relat Res 2013; 16:873-83. [PMID: 23551564 DOI: 10.1111/cid.12063] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
PURPOSE To develop a method for characterizing trabecular bone microarchitecture using cone beam computed tomography (CBCT) and to evaluate trabecular bone changes after rehabilitation using immediate versus delayed implant protocols. MATERIALS AND METHODS Six mongrel dogs randomly received 27 titanium implants in the maxillary incisor or mandibular premolar areas, following one of four protocols: (1) normal extraction socket healing; (2) immediate implant placement and immediate loading; (3) delayed implant placement and delayed loading; (4) delayed implant placement and immediate loading. The animals were euthanized at 8 weeks, and block biopsies were scanned using high resolution CBCT. Standard bone structural variables were assessed in coronal, middle, and apical levels. RESULTS Coronal and middle regions had more compact, more platelike, and thicker trabeculae. Protocols (2), (3), and (4) had significantly higher values (p < 0.001) than protocol (1) for bone surface density, bone surface volume ratio, and connectivity density, while significantly lower values (p < 0.001) were found for trabecular separation and fractal dimension. However, protocols (2), (3), and (4) did not show significantly different bone remodeling. CONCLUSIONS Compared with normal extraction healing, the implant protocols have an improved bone structural integration. Results do not suggest a different bone remodeling pattern when a delayed versus an immediate implant protocol is used.
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Affiliation(s)
- Yan Huang
- Oral Imaging Center, Department of Oral Health Science, KU Leuven, Leuven, Belgium; Oral Implant Center, West China College of Stomatology, Sichuan University, Chengdu, China
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20
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Wehrli FW. Magnetic resonance of calcified tissues. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2013; 229:35-48. [PMID: 23414678 PMCID: PMC4746726 DOI: 10.1016/j.jmr.2012.12.011] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2012] [Revised: 12/13/2012] [Accepted: 12/14/2012] [Indexed: 05/06/2023]
Abstract
MRI of the human body is largely made possible by the favorable relaxation properties of protons of water and triacyl glycerides prevalent in soft tissues. Hard tissues--key among them bone--are generally less amenable to measurement with in vivo MR imaging techniques, not so much as a result of the lower proton density but rather due to the extremely short life-times of the proton signal in water bound to solid-like entities, typically collagen, or being trapped in micro-pores. Either mechanism can enhance T2 relaxation by up to three orders of magnitude relative to their soft-tissue counterparts. Detection of these protons requires solid-state techniques that have emerged in recent years and that promise to add a new dimension to the study of hard tissues. Alternative approaches to probe calcified tissues exploit their characteristic magnetic properties. Bone, teeth and extra-osseous calcium-containing biomaterials are unique in that they are more diamagnetic than all other tissues and thus yield information indirectly by virtue of the induced magnetic fields present in their vicinity. Progress has also been made in methods allowing very high-resolution structural imaging of trabecular and cortical bone relying on detection of the surrounding soft-tissues. This brief review, much of it drawn from work conducted in the author's laboratory, seeks to highlight opportunities with focus on early-stage developments for image-based assessment of structure, function, physiology and mechanics of calcified tissues in humans via liquid and solid-state approaches, including proton, deuteron and phosphorus NMR and MRI.
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Affiliation(s)
- Felix W Wehrli
- Laboratory for Structural NMR Imaging, Department of Radiology, Perelman School of Medicine, University of Pennsylvania, USA.
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21
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Baum T, Kutscher M, Müller D, Räth C, Eckstein F, Lochmüller EM, Rummeny EJ, Link TM, Bauer JS. Cortical and trabecular bone structure analysis at the distal radius-prediction of biomechanical strength by DXA and MRI. J Bone Miner Metab 2013. [PMID: 23179228 DOI: 10.1007/s00774-012-0407-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The purpose of this study was to investigate whether the combination of dual-energy X-ray absorptiometry (DXA)-based bone mass and magnetic resonance imaging (MRI)-based cortical and trabecular structural measures improves the prediction of radial bone strength. Thirty-eight left forearms were harvested from formalin-fixed human cadavers. Bone mineral content (BMC) and bone mineral density (BMD) of the distal radius were measured using DXA. Cortical and trabecular structural measures of the distal radius were computed in high-resolution 1.5T MR images. Cortical measures included average cortical thickness and cross-sectional area. Trabecular measures included morphometric and texture parameters. The forearms were biomechanically tested in a fall simulation to measure absolute radial bone strength (failure load). Relative radial bone strength was determined by dividing radial failure loads by age, body mass index, radius length, and average radius cross-sectional area, respectively. DXA derived BMC and BMD showed statistically significant (p < 0.05) correlations with absolute and relative radial bone strength (r ≤ 0.78). Correlation coefficients for cortical and trabecular structural measures with absolute and relative radial bone strength amounted up to r = 0.59 and r = 0.74, respectively, (p < 0.05). In combination with DXA-based bone mass, trabecular but not, cortical structural measures, added in multiple regression models significant (p < 0.05) information in predicting absolute and relative radial bone strength (up to R adj = 0.88). Thus, a combination of DXA-based bone mass and MRI-based trabecular structural measures most accurately predicted absolute and relative radial bone strength, whereas structural measures of the cortex did not provide significant additional information in combination with DXA.
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Affiliation(s)
- Thomas Baum
- Klinikum rechts der Isar, Institut für Radiologie, Technische Universität München, Ismaninger Str. 22, 81675, Munich, Germany.
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22
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Graeff C, Marin F, Petto H, Kayser O, Reisinger A, Peña J, Zysset P, Glüer CC. High resolution quantitative computed tomography-based assessment of trabecular microstructure and strength estimates by finite-element analysis of the spine, but not DXA, reflects vertebral fracture status in men with glucocorticoid-induced osteoporosis. Bone 2013; 52:568-77. [PMID: 23149277 DOI: 10.1016/j.bone.2012.10.036] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2012] [Revised: 10/07/2012] [Accepted: 10/31/2012] [Indexed: 11/25/2022]
Abstract
High-resolution quantitative computed tomography (HRQCT)-based analysis of spinal bone density and microstructure, finite element analysis (FEA), and DXA were used to investigate the vertebral bone status of men with glucocorticoid-induced osteoporosis (GIO). DXA of L1-L3 and total hip, QCT of L1-L3, and HRQCT of T12 were available for 73 men (54.6±14.0years) with GIO. Prevalent vertebral fracture status was evaluated on radiographs using a semi-quantitative (SQ) score (normal=0 to severe fracture=3), and the spinal deformity index (SDI) score (sum of SQ scores of T4 to L4 vertebrae). Thirty-one (42.4%) subjects had prevalent vertebral fractures. Cortical BMD (Ct.BMD) and thickness (Ct.Th), trabecular BMD (Tb.BMD), apparent trabecular bone volume fraction (app.BV/TV), and apparent trabecular separation (app.Tb.Sp) were analyzed by HRQCT. Stiffness and strength of T12 were computed by HRQCT-based nonlinear FEA for axial compression, anterior bending and axial torsion. In logistic regressions adjusted for age, glucocorticoid dose and osteoporosis treatment, Tb.BMD was most closely associated with vertebral fracture status (standardized odds ratio [sOR]: Tb.BMD T12: 4.05 [95% CI: 1.8-9.0], Tb.BMD L1-L3: 3.95 [1.8-8.9]). Strength divided by cross-sectional area for axial compression showed the most significant association with spine fracture status among FEA variables (2.56 [1.29-5.07]). SDI was best predicted by a microstructural model using Ct.Th and app.Tb.Sp (r(2)=0.57, p<0.001). Spinal or hip DXA measurements did not show significant associations with fracture status or severity. In this cross-sectional study of males with GIO, QCT, HRQCT-based measurements and FEA variables were superior to DXA in discriminating between patients of differing prevalent vertebral fracture status. A microstructural model combining aspects of cortical and trabecular bone reflected fracture severity most accurately.
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Affiliation(s)
- Christian Graeff
- Sektion Biomedizinische Bildgebung, Klinik für Diagnostische Radiologie, Universitätsklinikum Schleswig-Holstein, Kiel, Germany.
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23
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Characterisation of Trabecular Bone Structure. STUDIES IN MECHANOBIOLOGY, TISSUE ENGINEERING AND BIOMATERIALS 2013. [DOI: 10.1007/8415_2011_113] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Terzi H, Cırpan T, Terzi R, Yeniel AÖ, Aktuğ H, Bilgin O. Osteoprotective effect of hormone therapy on bone microarchitecture before impaired bone mineral density in ovariectomized rats. J Turk Ger Gynecol Assoc 2012; 13:261-6. [PMID: 24592053 DOI: 10.5152/jtgga.2012.42] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2012] [Accepted: 10/27/2012] [Indexed: 12/31/2022] Open
Abstract
OBJECTIVE We aimed to determine the effect of hormone replacement therapy on bone microarchitecture in ovariectomized rats. MATERIAL AND METHODS In the Animal Ethics Committee approved-study, the effect of treatment with 17 β-estradiol 50 μg/kg and medroxyprogesterone 2.5 mg/kg on bone architecture and bone mineral density in rats versus ovariectomized control rats over the course of 20 days were evaluated. Femoral and lumbar bone mineral density levels and morphometric measurements were performed. RESULTS There were no significant differences in the femoral and lumbar bone mineral density levels between the groups. In the intact control group, the trabecular structures were significantly superior to those in the other groups. Additionally, the osteoblast count was significantly higher while the osteoclast count was significantly lower than in all other groups. Two parameters reflecting trabecular bone microarchitecture, which include the trabecular count and the trabecular area, demonstrated significant improvement in the hormone replacement group when compared to the ovariectomized control group. In the hormone replacement groups, the osteoblast count was significantly higher while the osteoclast count was significantly lower than in the ovariectomized control group. CONCLUSION We suggest that offering estrogen alone or in combination with progestogen can be a beneficial approach in preventing early postmenopausal bone loss regardless of bone mineral density.
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Affiliation(s)
- Hasan Terzi
- Department of Gynecology and Obstetrics, Derince Training and Research Hospital, Kocaeli, Turkey
| | - Teksin Cırpan
- Department of Gynecology and Obstetrics, Faculty of Medicine, Ege University, İzmir, Turkey
| | - Rabia Terzi
- Department of Physical Medicine and Rehabilitation, Derince Training and Research Hospital, Kocaeli, Turkey
| | - Ahmet Özgür Yeniel
- Department of Gynecology and Obstetrics, Faculty of Medicine, Ege University, İzmir, Turkey
| | - Hüseyin Aktuğ
- Department of Histology, Faculty of Medicine, Ege University, İzmir, Turkey
| | - Onur Bilgin
- Department of Gynecology and Obstetrics, Faculty of Medicine, Ege University, İzmir, Turkey
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Kijowski R, Tuite M, Kruger D, Munoz Del Rio A, Kleerekoper M, Binkley N. Evaluation of trabecular microarchitecture in nonosteoporotic postmenopausal women with and without fracture. J Bone Miner Res 2012; 27:1494-500. [PMID: 22407970 PMCID: PMC3377771 DOI: 10.1002/jbmr.1595] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
This study compared microscopic magnetic resonance imaging (µMRI) parameters of trabecular microarchitecture between postmenopausal women with and without fracture who have normal or osteopenic bone mineral density (BMD) on dual-energy X-ray absorptiometry (DXA). It included 36 postmenopausal white women 50 years of age and older with normal or osteopenic BMD (T-scores better than -2.5 at the lumbar spine, proximal femur, and one-third radius on DXA). Eighteen women had a history of low-energy fracture, whereas 18 women had no history of fracture and served as an age, race, and ultradistal radius BMD-matched control group. A three-dimensional fast large-angle spin-echo (FLASE) sequence with 137 µm × 137 µm × 400 µm resolution was performed through the nondominant wrist of all 36 women using the same 1.5T scanner. The high-resolution images were used to measure trabecular bone volume fraction, trabecular thickness, surface-to-curve ratio, and erosion index. Wilcoxon signed-rank tests were used to compare differences in BMD and µMRI parameters between postmenopausal women with and without fracture. Post-menopausal women with fracture had significantly lower (p < 0.05) trabecular bone volume fraction and surface-to-curve ratio and significantly higher (p < 0.05) erosion index than postmenopausal women without fracture. There was no significant difference between postmenopausal women with and without fracture in trabecular thickness (p = 0.80) and BMD of the spine (p = 0.21), proximal femur (p = 0.19), one-third radius (p = 0.47), and ultradistal radius (p = 0.90). Postmenopausal women with normal or osteopenic BMD who had a history of low-energy fracture had significantly different (p < 0.05) µMRI parameters than an age, race, and ultradistal radius BMD-matched control group of postmenopausal women with no history of fracture. Our study suggests that µMRI can be used to identify individuals without a DXA-based diagnosis of osteoporosis who have impaired trabecular microarchitecture and thus a heretofore-unappreciated elevated fracture risk.
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Affiliation(s)
- Richard Kijowski
- Department of Radiology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53792-3252, USA.
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Abstract
Osteoporosis heightens vertebral fragility owing to the biomechanical effects of diminished bone structure and composition. These biomechanical effects are only partially explained by loss in bone mass, so additional factors that are independent of bone mass are also thought to play an important role in vertebral fragility. Recent advances in imaging equipment, imaging-processing methods, and computational capacity allow researchers to quantify trabecular architecture in the vertebra at the level of the individual trabecular elements and to derive biomechanics-based measures of architecture that are independent of bone mass and density. These advances have shed light on the role of architecture in vertebral fragility. In addition to the adverse biomechanical consequences associated with trabecular thinning and loss of connectivity, a reduction in the number of vertical trabecular plates appears to be particularly harmful to vertebral strength. In the clinic, detailed architecture analysis is primarily applied to peripheral sites such as the distal radius and tibia. Analysis of trabecular architecture at these peripheral sites has shown mixed results for discriminating between patients with and without a vertebral fracture independent of bone mass, but has the potential to provide unique insight into the effects of therapeutic treatments. Overall, it does appear that trabecular architecture has an independent role on vertebral strength. Additional research is required to determine how and where architecture should be measured in vivo and whether assessment of trabecular architecture in a clinical setting improves prospective fracture risk assessment for the vertebra.
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Affiliation(s)
- Aaron J Fields
- Department of Orthopaedic Surgery, University of California, 513 Parnassus Avenue, S-1161, San Francisco, CA, 94143-0514, USA.
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Atkinson EJ, Therneau TM, Melton LJ, Camp JJ, Achenbach SJ, Amin S, Khosta S. Assessing fracture risk using gradient boosting machine (GBM) models. J Bone Miner Res 2012; 27:1397-404. [PMID: 22367889 PMCID: PMC3408850 DOI: 10.1002/jbmr.1577] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Advanced bone imaging with quantitative computed tomography (QCT) has had limited success in significantly improving fracture prediction beyond standard areal bone mineral density (aBMD) measurements. Thus, we examined whether a machine learning paradigm, gradient boosting machine (GBM) modeling, which can incorporate diverse measurements of bone density and geometry from central QCT imaging and of bone microstructure from high-resolution peripheral QCT imaging, can improve fracture prediction. We studied two cohorts of postmenopausal women: 105 with and 99 without distal forearm fractures (Distal Forearm Cohort) and 40 with at least one grade 2 or 3 vertebral deformity and 78 with no vertebral fracture (Vertebral Cohort). Within each cohort, individual bone density, structure, or strength variables had areas under receiver operating characteristic curves (AUCs) ranging from 0.50 to 0.84 (median 0.61) for discriminating women with and without fracture. Using all possible variables in the GBM model, the AUCs were close to 1.0. Fracture predictions in the Vertebral Cohort using the GBM models built with the Distal Forearm Cohort had AUCs of 0.82-0.95, while predictions in the Distal Forearm Cohort using models built with the Vertebral Cohort had AUCs of 0.80-0.83. Attempts at capturing a comparable parametric model using the top variables from the Distal Forearm Cohort resulted in resulted in an AUC of 0.81. Relatively high AUCs for differing fracture types suggest that an underlying fracture propensity is being captured by this modeling approach. More complex modeling, such as with GBM, creates stronger fracture predictions and may allow deeper insights into information provided by advanced bone imaging techniques.
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Affiliation(s)
- Elizabeth J Atkinson
- Divisions of Biomedical Statistics and Informatics, College of Medicine, Mayo Clinic, Rochester, MN, USA.
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Rajapakse CS, Leonard MB, Bhagat YA, Sun W, Magland JF, Wehrli FW. Micro-MR imaging-based computational biomechanics demonstrates reduction in cortical and trabecular bone strength after renal transplantation. Radiology 2012; 262:912-20. [PMID: 22357891 DOI: 10.1148/radiol.11111044] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
PURPOSE To examine the ability of three-dimensional micro-magnetic resonance (MR) imaging-based computational biomechanics to detect mechanical alterations in trabecular bone and cortical bone in the distal tibia of incident renal transplant recipients 6 months after renal transplantation and compare them with bone mineral density (BMD) outcomes. MATERIALS AND METHODS The study was approved by the institutional review board and complied with HIPAA guidelines. Written informed consent was obtained from all subjects. Micro-MR imaging of distal tibial metaphysis was performed within 2 weeks after renal transplantation (baseline) and 6 months later in 49 participants (24 female; median age, 44 years; range, 19-61 years) with a clinical 1.5-T whole-body imager using a modified three-dimensional fast large-angle spin-echo pulse sequence. Micro-finite-element models for cortical bone, trabecular bone, and whole-bone section were generated from each image by delineating the endosteal and periosteal boundaries. Mechanical parameters (stiffness and failure load) were estimated with simulated uniaxial compression tests on the micro-finite-element models. Structural parameters (trabecular bone volume fraction [BV/TV, bone volume to total volume ratio], trabecular thickness [TbTh], and cortical thickness [CtTh]) were computed from micro-MR images. Total hip and spine areal BMD were determined with dual-energy x-ray absorptiometry (DXA). Parameters obtained at the follow-up were compared with the baseline values by using parametric or nonparametric tests depending on the normality of data. RESULTS All mechanical parameters were significantly lower at 6 months compared with baseline. Decreases in cortical bone, trabecular bone, and whole-bone stiffness were 3.7% (P = .03), 4.9% (P = .03), and 4.3% (P = .003), respectively. Decreases in cortical bone, trabecular bone, and whole-bone failure strength were 7.6% (P = .0003), 6.0% (P = .004), and 5.6% (P = .0004), respectively. Conventional structural measures, BV/TV, TbTh, and CtTh, did not change significantly. Spine BMD decreased by 2.9% (P < .0001), while hip BMD did not change significantly at DXA. CONCLUSION MR imaging-based micro-finite-element analysis suggests that stiffness and failure strength of the distal tibia decrease over a 6-month interval after renal transplantation.
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Affiliation(s)
- Chamith S Rajapakse
- Department of Radiology, University of Pennsylvania, 1 Founders, 3400 Spruce St, Philadelphia, PA 19104, USA.
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Bhagat YA, Rajapakse CS, Magland JF, Wald MJ, Song HK, Leonard MB, Wehrli FW. On the significance of motion degradation in high-resolution 3D μMRI of trabecular bone. Acad Radiol 2011; 18:1205-16. [PMID: 21816638 DOI: 10.1016/j.acra.2011.06.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2011] [Revised: 06/26/2011] [Accepted: 06/22/2011] [Indexed: 11/17/2022]
Abstract
RATIONALE AND OBJECTIVES Subtle subject movement during high-resolution three-dimensional micro-magnetic resonance imaging of trabecular bone (TB) causes blurring, thereby rendering the data unreliable for quantitative analysis. In this work, the effects of translational and rotational motion displacements were evaluated qualitatively and quantitatively. MATERIALS AND METHODS In experiment 1, motion was induced by applying various simulated and previously observed in vivo trajectories as phase shifts to k-space or rotation angles to k-space segments of a virtually motion-free data set. In experiment 2, images that were visually free of motion artifacts from two groups of 10 healthy individuals, differing in age, were selected to probe the effects of motion on TB parameters. In both experiments, images were rated for motion severity, and the scores were compared to a focus criterion, the normalized gradient squared. RESULTS Strong correlations were observed between the motion quality scores and the corresponding normalized gradient squared values (R(2) = 0.52-0.64, P < .01). The results from experiment 1 demonstrated consistently lower image quality and alterations in structural parameters of 9% to 45% with increased amplitude of displacements. In experiment 2, the significant differences in structural parameter group means of the motion-free images were lost upon motion degradation. Autofocusing, a postprocessing correction method, partially recovered the sharpness of the original motion-free images in 13 of 20 subjects. CONCLUSIONS Quantitative TB structural measures are highly sensitive to subtle motion-induced degradation, which adversely affects precision and statistical power. The results underscore the influence of subject movement in high-resolution three-dimensional micro-magnetic resonance imaging and its correction for TB structure analysis.
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Affiliation(s)
- Yusuf A Bhagat
- Laboratory for Structural NMR Imaging, Department of Radiology, University of Pennsylvania Medical Center, Philadelphia, 19104, USA
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Lam SCB, Wald MJ, Rajapakse CS, Liu Y, Saha PK, Wehrli FW. Performance of the MRI-based virtual bone biopsy in the distal radius: serial reproducibility and reliability of structural and mechanical parameters in women representative of osteoporosis study populations. Bone 2011; 49:895-903. [PMID: 21784189 PMCID: PMC3167016 DOI: 10.1016/j.bone.2011.07.010] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2011] [Revised: 06/14/2011] [Accepted: 07/08/2011] [Indexed: 11/25/2022]
Abstract
Serial reproducibility and reliability critically determine sensitivity to detect changes in response to intervention and provide a basis for sample size estimates. Here, we evaluated the performance of the MRI-based virtual bone biopsy in terms of 26 structural and mechanical parameters in the distal radius of 20 women in the age range of 50 to 75 years (mean=62.0 years, S.D.=8.1 years), representative of typical study populations in drug intervention trials and fracture studies. Subjects were examined three times at average intervals of 20.2 days (S.D.=14.5 days) by MRI at 1.5 T field strength at a voxel size of 137×137×410 μm(3). Methods involved prospective and retrospective 3D image registration and auto-focus motion correction. Analyses were performed from a central 5×5×5 mm(3) cuboid subvolume and trabecular volume consisting of a 13 mm axial slab encompassing the entire medullary cavity. Whole-volume axial stiffness and sub-regional Young's and shear moduli were computed by finite-element analysis. Whole-volume-derived aggregate mean coefficient of variation of all structural parameters was 4.4% (range 1.8% to 7.7%) and 4.0% for axial stiffness; corresponding data in the subvolume were 6.5% (range 1.6% to 13.0%) for structural, and 5.5% (range 4.6% to 6.5%) for mechanical parameters. Aggregate ICC was 0.976 (range 0.947 to 0.986) and 0.992 for whole-volume-derived structural parameters and axial stiffness, and 0.946 (range 0.752 to 0.991) and 0.974 (range 0.965 to 0.978) for subvolume-derived structural and mechanical parameters, respectively. The strongest predictors of whole-volume axial stiffness were BV/TV, junction density, skeleton density and Tb.N (R(2) 0.79-0.87). The same parameters were also highly predictive of sub-regional axial modulus (R(2) 0.88-0.91). The data suggest that the method is suited for longitudinal assessment of the response to therapy. The underlying technology is portable and should be compatible with all general-purpose MRI scanners, which is appealing considering the very large installed base of this modality.
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Affiliation(s)
- Shing Chun Benny Lam
- Laboratory for Structural NMR Imaging, Department of Radiology, University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA 19104, USA.
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Bhagat YA, Rajapakse CS, Magland JF, Love JH, Wright AC, Wald MJ, Song HK, Wehrli FW. Performance of μMRI-Based virtual bone biopsy for structural and mechanical analysis at the distal tibia at 7T field strength. J Magn Reson Imaging 2011; 33:372-81. [PMID: 21274979 DOI: 10.1002/jmri.22439] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
PURPOSE To assess the performance of a 3D fast spin echo (FSE) pulse sequence utilizing out-of-slab cancellation through phase alternation and micro-magnetic resonance imaging (μMRI)-based virtual bone biopsy processing methods to probe the serial reproducibility and sensitivity of structural and mechanical parameters of the distal tibia at 7.0T. MATERIALS AND METHODS The distal tibia of five healthy subjects was imaged at three timepoints with a 3D FSE sequence at 137 × 137 × 410 μm(3) voxel size. Follow-up images were retrospectively 3D registered to baseline images. Coefficients of variation (CV) and intraclass correlation coefficients (ICCs) for measures of scale and topology of the whole tibial trabecular bone (TB) cross-section as well as finite-element-derived Young's and shear moduli of central cuboidal TB subvolumes (8 × 8 × 5 mm(3) ) were evaluated as measures of reproducibility and reliability. Four additional cubic TB subregions (anterior, medial, lateral, and posterior) of similar dimensions were extracted and analyzed to determine associations between whole cross-section and subregional structural parameters. RESULTS The mean signal-to-noise ratio (SNR) over the 15 image acquisitions was 27.5 ± 2.1. Retrospective registration yielded an average common analysis volume of 67% across the three exams per subject. Reproducibility (mean CV = 3.6%; range, 1.5%-5%) and reliability (ICCs, 0.95-0.99) of all parameters permitted parameter-based discrimination of the five subjects in spite of the narrow age range (26-36 years) covered. Parameters characterizing topology were better able to distinguish two individuals who demonstrated similar values for scalar measurements (≈ 34% difference, P < 0.001). Whole-section axial stiffness encompassing the cortex was superior at distinguishing two individuals relative to its central subregional TB counterpart (≈ 8% difference; P < 0.05). Interregion comparisons showed that although all parameters were correlated (mean R(2) = 0.78; range 0.57-0.99), the strongest associations observed were those for the erosion index (mean R(2) = 0.95, P ≤ 0.01). CONCLUSION The reproducibility and structural and mechanical parameter-based discriminative ability achieved in five healthy subjects suggests that 7T-derived μMRI of TB can be applied towards serial patient studies of osteoporosis and may enable earlier detection of disease or treatment-based effects.
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Affiliation(s)
- Yusuf A Bhagat
- Laboratory for Structural NMR Imaging, Department of Radiology, University of Pennsylvania, MRI Education Center, Philadelphia, Pennsylvania 19104, USA
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Ito M. Recent progress in bone imaging for osteoporosis research. J Bone Miner Metab 2011; 29:131-40. [PMID: 21301898 DOI: 10.1007/s00774-010-0258-0] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2010] [Accepted: 12/27/2010] [Indexed: 01/28/2023]
Abstract
Advances in bone imaging techniques have provided tools for analyzing bone structure at the macro-, micro- and nano-level. Quantitative assessment of macrostructure can be achieved using dual X-ray absorptiometry (DXA) and quantitative computed tomography (QCT), particularly volumetric quantitative CT (vQCT). In vivo quantitative techniques for assessing the microstructure of trabecular bone non-invasively and non-destructively include high-resolution CT (HR-CT) and high-resolution magnetic resonance (HR-MR). Compared with MR imaging, CT-based techniques have the advantage of directly visualizing the bone in the axial skeleton, with high spatial resolution, but the disadvantage of delivering a considerable radiation dose. Micro-CT (μCT), which provides a higher resolution of the microstructure and is principally applicable in vitro, has undergone technological advances such that it is now able to elucidate the physiological skeletal change mechanisms associated with aging and determine the effects of therapeutic intervention on the bone microstructure. In particular, synchrotron μCT (SR-CT) provides a more detailed view of trabecular structure at the nano-level. For the assessment of hip geometry, DXA-based hip structure analysis (HSA) and CT-based HSA have been developed. DXA-based HSA is a convenient tool for analyzing biomechanical properties and for assuming cross-sectional hip geometry based on two-dimensional (2D) data, whereas CT-based HSA provides these parameters three-dimensionally in robust relationship with biomechanical properties, at the cost of greater radiation exposure and the lengthy time required for the analytical procedure. Further progress in bone imaging technology is promising to bring new aspects of bone structure in relation to bone strength to light, and to establish a means for analyzing bone structural properties in the everyday clinical setting.
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Affiliation(s)
- Masako Ito
- Department of Radiology, Nagasaki University School of Medicine, 1-7-1 Sakamoto, Nagasaki, 852-8501, Japan.
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The Role of the Radiologist When Encountering Osteoporosis in Women. AJR Am J Roentgenol 2011; 196:331-7. [DOI: 10.2214/ajr.10.5606] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Fields AJ, Lee GL, Liu XS, Jekir MG, Guo XE, Keaveny TM. Influence of vertical trabeculae on the compressive strength of the human vertebra. J Bone Miner Res 2011; 26:263-9. [PMID: 20715186 PMCID: PMC3179351 DOI: 10.1002/jbmr.207] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Vertebral strength, a key etiologic factor of osteoporotic fracture, may be affected by the relative amount of vertically oriented trabeculae. To better understand this issue, we performed experimental compression testing, high-resolution micro-computed tomography (µCT), and micro-finite-element analysis on 16 elderly human thoracic ninth (T(9)) whole vertebral bodies (ages 77.5 ± 10.1 years). Individual trabeculae segmentation of the µCT images was used to classify the trabeculae by their orientation. We found that the bone volume fraction (BV/TV) of just the vertical trabeculae accounted for substantially more of the observed variation in measured vertebral strength than did the bone volume fraction of all trabeculae (r(2) = 0.83 versus 0.59, p < .005). The bone volume fraction of the oblique or horizontal trabeculae was not associated with vertebral strength. Finite-element analysis indicated that removal of the cortical shell did not appreciably alter these trends; it also revealed that the major load paths occur through parallel columns of vertically oriented bone. Taken together, these findings suggest that variation in vertebral strength across individuals is due primarily to variations in the bone volume fraction of vertical trabeculae. The vertical tissue fraction, a new bone quality parameter that we introduced to reflect these findings, was both a significant predictor of vertebral strength alone (r(2) = 0.81) and after accounting for variations in total bone volume fraction in multiple regression (total R(2) = 0.93). We conclude that the vertical tissue fraction is a potentially powerful microarchitectural determinant of vertebral strength.
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Affiliation(s)
- Aaron J Fields
- Orthopaedic Biomechanics Laboratory, Department of Mechanical Engineering, University of California, Berkeley, CA 94720-1740, USA.
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Issever AS, Link TM, Newitt D, Munoz T, Majumdar S. Interrelationships between 3-T-MRI-derived cortical and trabecular bone structure parameters and quantitative-computed-tomography-derivedbone mineral density. Magn Reson Imaging 2010; 28:1299-305. [PMID: 20685052 PMCID: PMC2963712 DOI: 10.1016/j.mri.2010.06.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2009] [Revised: 03/10/2010] [Accepted: 06/10/2010] [Indexed: 01/23/2023]
Abstract
Recently, 3-T magnetic resonance imaging (MRI) has been introduced for bone imaging. Through higher signal-to-noise ratios, as compared to 1.5-T MRI, it promises to be a more powerful tool for the assessment of cortical and trabecular bone measures. The goal of our study was to compare MRI-derived cortical and trabecular bone measures to quantitative computed tomography (QCT)-derived bone mineral density (BMD). Using 3-T MRI in 51 postmenopausal women, apparent (app.) measures of bone volume/total volume, trabecular number (Tb.N), trabecular thickness (Tb.Th) and trabecular separation were derived at the distal radius, distal tibia and calcaneus. Cortical thickness (Ct.Th) was calculated at the distal radius and distal tibia. These measures were compared to QCT-derived BMD of the spine, hip and radius. Significant correlations ((*)P<.05; (**)P<.001; (***)P<.0001) were found between spine BMD- and MRI-derived Ct.Th (r(radius)=.55, (*)P<.05; r(tibia)=.67, (***)P<.0001) and app. Tb.N (r(radius)=.33, (*)P<.05; r(tibia)=.35, (*)P<.05) at the radius and tibia. Furthermore, within the first 10 mm at the radius, an inverse correlation for Ct.Th and app. BV/TV (r(6mm)=-.56, P<.001; r(10mm)=-.36, P<.05) and app. Tb.Th (r(6mm)=-.54, P<.001; r(10mm)=-.41, P<.05) was found.
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Affiliation(s)
- Ahi Sema Issever
- Musculoskeletal and Quantitative Imaging Research Group, Department of Radiology and Biomedical Imaging, University of California, China Basin, San Francisco, CA 94107, USA.
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Liu XS, Cohen A, Shane E, Yin PT, Stein EM, Rogers H, Kokolus SL, McMahon DJ, Lappe JM, Recker RR, Lang T, Guo XE. Bone density, geometry, microstructure, and stiffness: Relationships between peripheral and central skeletal sites assessed by DXA, HR-pQCT, and cQCT in premenopausal women. J Bone Miner Res 2010; 25:2229-38. [PMID: 20499344 PMCID: PMC3128822 DOI: 10.1002/jbmr.111] [Citation(s) in RCA: 128] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
High-resolution peripheral quantitative computed tomography (HR-pQCT) is a new in vivo imaging technique for assessing 3D microstructure of cortical and trabecular bone at the distal radius and tibia. No studies have investigated the extent to which measurements of the peripheral skeleton by HR-pQCT reflect those of the spine and hip, where the most serious fractures occur. To address this research question, we performed dual-energy X-ray absorptiometry (DXA), central QCT (cQCT), HR-pQCT, and image-based finite-element analyses on 69 premenopausal women to evaluate relationships among cortical and trabecular bone density, geometry, microstructure, and stiffness of the lumbar spine, proximal femur, distal radius, and distal tibia. Significant correlations were found between the stiffness of the two peripheral sites (r = 0.86), two central sites (r = 0.49), and between the peripheral and central skeletal sites (r = 0.56-0.70). These associations were explained in part by significant correlations in areal bone mineral density (aBMD), volumetric bone mineral density (vBMD), and cross-sectional area (CSA) between the multiple skeletal sites. For the prediction of proximal femoral stiffness, vBMD (r = 0.75) and stiffness (r = 0.69) of the distal tibia by HR-pQCT were comparable with direct measurements of the proximal femur: aBMD of the hip by DXA (r = 0.70) and vBMD of the hip by cQCT (r = 0.64). For the prediction of vertebral stiffness, trabecular vBMD (r = 0.58) and stiffness (r = 0.70) of distal radius by HR-pQCT were comparable with direct measurements of lumbar spine: aBMD by DXA (r = 0.78) and vBMD by cQCT (r = 0.67). Our results suggest that bone density and microstructural and mechanical properties measured by HR-pQCT of the distal radius and tibia reflect the mechanical competence of the central skeleton.
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Affiliation(s)
- X Sherry Liu
- Division of Endocrinology, Department of Medicine, Columbia University, New York, NY 10027, USA
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Liu XS, Zhang XH, Rajapakse CS, Wald MJ, Magland J, Sekhon KK, Adam MF, Sajda P, Wehrli FW, Guo XE. Accuracy of high-resolution in vivo micro magnetic resonance imaging for measurements of microstructural and mechanical properties of human distal tibial bone. J Bone Miner Res 2010; 25:2039-50. [PMID: 20499379 PMCID: PMC3118020 DOI: 10.1002/jbmr.92] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Micro magnetic resonance imaging (µMRI) is an in vivo imaging method that permits 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 µMRI-based microstructural and µFE analyses to become standard clinical tools for assessing bone quality, validation with a current gold standard, namely, high-resolution micro computed tomography (µCT), is required. Microstructural measurements of 25 human cadaveric distal tibias were performed for the registered µMR and µCT images, respectively. Next, whole bone stiffness, trabecular bone stiffness, and elastic moduli of cubic subvolumes 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) based on µMRI showed strong correlations with µCT measurements (r(2) = 0.67 to 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 to 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*) based on µMRI had no correlation with the µCT measurement and did not contribute to any mechanical measurement. Furthermore, the whole bone and trabecular bone stiffness based on µMRI were highly correlated with 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 subvolume had significant but only moderate correlations with their gold standards (r(2) = 0.40 to 0.58). We conclude that most microstructural and mechanical properties of the distal tibia can be derived efficiently from µMR images and can provide additional information regarding bone quality.
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Affiliation(s)
- X Sherry Liu
- Division of Endocrinology, Department of Medicine, Columbia University, New York, NY 10027, USA
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Wehrli FW, Rajapakse CS, Magland JF, Snyder PJ. Mechanical implications of estrogen supplementation in early postmenopausal women. J Bone Miner Res 2010; 25:1406-14. [PMID: 20200948 PMCID: PMC3153138 DOI: 10.1002/jbmr.33] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Whereas the structural implications of drug intervention are well established, there are few data on the possible mechanical consequences of treatment. In this work we examined the changes in elastic and shear moduli (EM and SM) in a region of trabecular bone in the distal radius and distal tibia of early postmenopausal women on the basis of MRI-based micro-finite-element (microFE) analysis. Whole-section axial stiffness (AS) encompassing both trabecular and cortical compartments was evaluated as well. The study was conducted on previously acquired high-resolution images at the two anatomic sites. Images were processed to yield a 3D voxel array of bone-volume fraction (BVF), which was converted to a microFE model of hexahedral elements in which tissue modulus was set proportional to voxel BVF. The study comprised 65 early postmenopausal women (age range 45 to 55 years), of whom 32 had chosen estrogen supplementation (estradiol group); the remainder had not (control group). Subjects had been scanned at baseline and 12 and 24 months thereafter. At the distal tibia, EM and SM were reduced by 2.9% to 5.5% in the control group (p < .05 to <.005), but there was no change in the estradiol subjects. AS decreased 3.9% (4.0%) in controls (p < .005) and increased by 5.8% (6.2%) in estradiol group subjects (p < .05) at 12 (24) months. At the distal radius, EM and SM changes from baseline were not significant, but at both time points AS was increased in estradiol group subjects and decreased in controls (p < .005 to <.05), albeit by a smaller margin than at the tibia. EM and SM were strongly correlated with BV/TV (r(2) = 0.44 to 0.92) as well as with topologic parameters expressing the ratio of plates to rods (r(2) = 0.45 to 0.82), jointly explaining up to 96% of the variation in the mechanical parameters. Finally, baseline AS was strongly correlated between the two anatomic sites (r(2) = 0.58), suggesting that intersubject variations in the bone's mechanical competence follows similar mechanisms. In conclusion, the results demonstrate that micro-MRI-based microFE models are suited for the study of the mechanical implications of antiresorptive treatment. The data further highlight the anabolic effect of short-term estrogen supplementation.
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Affiliation(s)
- Felix W Wehrli
- Department of Radiology, University of Pennsylvania, Philadelphia, PA 19104, USA.
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Greenspan SL, Perera S, Recker R, Wagner JM, Greeley P, Gomberg BR, Seaman P, Kleerekoper M. Changes in trabecular microarchitecture in postmenopausal women on bisphosphonate therapy. Bone 2010; 46:1006-10. [PMID: 20051275 PMCID: PMC3889111 DOI: 10.1016/j.bone.2009.12.025] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2009] [Revised: 12/18/2009] [Accepted: 12/22/2009] [Indexed: 11/30/2022]
Abstract
PURPOSE In addition to bone mineral density (BMD), trabecular microstructure contributes to skeletal strength. Our goal was to examine changes in trabecular microstructure in women on therapy. MATERIALS AND METHODS We followed 10 postmenopausal women receiving a bisphosphonate, risedronate (35 mg once weekly), over 12 months and examined trabecular microarchitecture with high resolution wrist MR images (hr-MRI). MRI parameters included bone volume/total volume (BV/TV), surface density (representing plates), curve density (representing rods), surface-to-curve ratio and erosion index (depicting deterioration). We assessed BMD of the spine, hip and radius and markers of bone turnover. RESULTS Women had been receiving bisphosphonate therapy for 43+/-9 months (mean+/-SD) prior to the first MRI. Indices of hr-MRI demonstrated improvement in surface-to-curve ratio (13.0%) and a decrease in erosion index (12.1%) consistent with less deterioration (both p<0.05). BMD of the spine, hip and radius and markers of bone turnover remained stable. Parameters of hr-MRI were associated with 1/3 distal radius BMD (correlation coefficient 0.71 to 0.86, p<0.05). DISCUSSION We conclude that hr-MRI of the radius demonstrates improvements in trabecular microstructure not appreciated by conventional BMD and provides additional information on parameters that contribute to structural integrity in patients on antiresorptive therapy.
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Affiliation(s)
| | - Subashan Perera
- University of Pittsburgh, Department of Medicine, Pittsburgh, PA
| | | | - Julie M. Wagner
- University of Pittsburgh, Department of Medicine, Pittsburgh, PA
| | - Parmatma Greeley
- University of Pittsburgh, Department of Medicine, Pittsburgh, PA
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Bauer JS, Link TM. Advances in osteoporosis imaging. Eur J Radiol 2009; 71:440-9. [PMID: 19651482 DOI: 10.1016/j.ejrad.2008.04.064] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2008] [Accepted: 04/30/2008] [Indexed: 11/26/2022]
Abstract
In the assessment of osteoporosis, the measurement of bone mineral density (BMD(a)) obtained from dual energy X-ray absorptiometry (DXA; g/cm(2)) is the most widely used parameter. However, bone strength and fracture risk are also influenced by parameters of bone quality such as micro-architecture and tissue properties. This article reviews the radiological techniques currently available for imaging and quantifying bone structure, as well as advanced techniques to image bone quality. With the recent developments in magnetic resonance (MR) techniques, including the availability of clinical 3T scanners, and advances in computed tomography (CT) technology (e.g. clinical Micro-CT), in-vivo imaging of the trabecular bone architecture is becoming more feasible. Several in-vitro studies have demonstrated that bone architecture, measured by MR or CT, was a BMD-independent determinant of bone strength. In-vivo studies showed that patients with, and without, osteoporotic fractures could better be separated with parameters of bone architecture than with BMD. Parameters of trabecular architecture were more sensitive to treatment effects than BMD. Besides the 3D tomographic techniques, projection radiography has been used in the peripheral skeleton as an additional tool to better predict fracture risk than BMD alone. The quantification of the trabecular architecture included parameters of scale, shape, anisotropy and connectivity. Finite element analyses required highest resolution, but best predicted the biomechanical properties of the bone. MR diffusion and perfusion imaging and MR spectroscopy may provide measures of bone quality beyond trabecular micro-architecture.
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Affiliation(s)
- Jan S Bauer
- Department of Radiology, UCSF, San Francisco, CA, USA.
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Haïat G, Padilla F, Svrcekova M, Chevalier Y, Pahr D, Peyrin F, Laugier P, Zysset P. Relationship between ultrasonic parameters and apparent trabecular bone elastic modulus: a numerical approach. J Biomech 2009; 42:2033-9. [PMID: 19646703 DOI: 10.1016/j.jbiomech.2009.06.008] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2009] [Revised: 06/04/2009] [Accepted: 06/05/2009] [Indexed: 11/19/2022]
Abstract
The physical principles underlying quantitative ultrasound (QUS) measurements in trabecular bone are not fully understood. The translation of QUS results into bone strength remains elusive. However, ultrasound being mechanical waves, it is likely to assess apparent bone elasticity. The aim of this study is to derive the sensitivity of QUS parameters to variations of apparent bone elasticity, a surrogate for strength. The geometry of 34 human trabecular bone samples cut in the great trochanter was reconstructed using 3-D synchrotron micro-computed tomography. Finite-difference time-domain simulations coupled to 3-D micro-structural models were performed in the three perpendicular directions for each sample and each direction. A voxel-based micro-finite element linear analysis was employed to compute the apparent Young's modulus (E) of each sample for each direction. For the antero-posterior direction, the predictive power of speed of sound and normalized broadband ultrasonic attenuation to assess E was equal to 0.9 and 0.87, respectively, which is better than what is obtained using bone density alone or coupled with micro-architectural parameters and of the same order of what can be achieved with the fabric tensor approach. When the direction of testing is parallel to the main trabecular orientation, the predictive power of QUS parameters decreases and the fabric tensor approach always gives the best results. This decrease can be explained by the presence of two longitudinal wave modes. Our results, which were obtained using two distinct simulation tools applied on the same set of samples, highlight the potential of QUS techniques to assess bone strength.
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Affiliation(s)
- G Haïat
- CNRS, Université Paris 7, Laboratoire de Recherches Orthopédiques, UMR CNRS 7052 B2OA, 75010 Paris, France.
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Carballido-Gamio J, Krug R, Huber MB, Hyun B, Eckstein F, Majumdar S, Link TM. Geodesic topological analysis of trabecular bone microarchitecture from high-spatial resolution magnetic resonance images. Magn Reson Med 2009; 61:448-56. [PMID: 19161163 DOI: 10.1002/mrm.21835] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
In vivo assessment of trabecular bone microarchitecture could improve the prediction of fracture risk and the efficacy of osteoporosis treatment and prevention. Geodesic topological analysis (GTA) is introduced as a novel technique to quantify the trabecular bone microarchitecture from high-spatial resolution magnetic resonance (MR) images. Trabecular bone parameters that quantify the scale, topology, and anisotropy of the trabecular bone network in terms of its junctions are the result of GTA. The reproducibility of GTA was tested with in vivo images of human distal tibiae and radii (n = 6) at 1.5 Tesla; and its ability to discriminate between subjects with and without vertebral fracture was assessed with ex vivo images of human calcanei at 1.5 and 3.0 Tesla (n = 30). GTA parameters yielded an average reproducibility of 4.8%, and their individual areas under the curve (AUC) of the receiver operating characteristic curve analysis for fracture discrimination performed better at 3.0 than at 1.5 Tesla reaching values of up to 0.78 (p < 0.001). Logistic regression analysis demonstrated that fracture discrimination was improved by combining GTA parameters, and that GTA combined with bone mineral density (BMD) allow for better discrimination than BMD alone (AUC = 0.95; p < 0.001). Results indicate that GTA can substantially contribute in studies of osteoporosis involving imaging of the trabecular bone microarchitecture.
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Affiliation(s)
- Julio Carballido-Gamio
- Musculoskeletal and Quantitative Imaging Research Group, Department of Radiology, University of California, San Francisco, San Francisco, California 94158, USA.
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Li CQ, Magland JF, Rajapakse CS, Guo XE, Zhang XH, Vasilic B, Wehrli FW. Implications of resolution and noise for in vivo micro-MRI of trabecular bone. Med Phys 2009; 35:5584-94. [PMID: 19175116 DOI: 10.1118/1.3005598] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Osteoporotic bone loss is accompanied by impaired structural integrity of the trabecular network, leading to a decrease in the overall mechanical properties of the bone. The development of the "virtual bone biopsy" (VBB), a method combining magnetic resonance microimaging (microMRI) and digital image processing techniques, has previously been shown to quantify topology and scale of human trabecular bone noninvasively. The aim of this work was to determine the extent to which structural parameters derived from images acquired in the limited spatial resolution regime of in vivo imaging are sensitive to resolution and noise and further, whether under these conditions, a small amount of bone loss and its associated structural manifestations can be detected. Toward these goals 3D models of trabecular bone representing multiple anatomic locations were generated on the basis of microCT images of human cadaveric bone cores. These images were binarized and the resulting data arrays representing pure bone (proton density=0) and pure marrow (proton density=255) subjected to simulated MR imaging by Cartesian sampling of k space, yielding, after 3D Fourier reconstruction, voxel sizes currently achievable in vivo. Subsequently, realistic levels of Gaussian noise were superimposed on the complex data and magnitude images were computed. The resulting images were subsequently VBB processed for a range of signal-to-noise ratio (SNR) values and image voxel sizes. For comparison of the predicted behavior to in vivo data, images from a recent patient study were evaluated as well. Systematic changes of the derived structural parameters changing progressively with decreasing SNR were noted, and it is shown that the errors are correctable using simple linear transformations, thereby allowing the data to be normalized. The predicted dependence of the structural parameters on SNR also closely parallel those observed in vivo. Finally, in order to assess the sensitivity of the VBB processing algorithms to detect bone loss during disease progression or regression in response to treatment, the high-resolution specimen data were subjected to 5% bone loss either by homogeneous or heterogeneous erosion and microMR images simulated at in vivo resolution and SNR. At typical in vivo SNR (SNR=12) and effective image resolution (160 microm isotropic and 137 x 137 X 410 microm3), VBB algorithms were able to detect the structural implications of a 5% loss in bone volume fraction with high statistical significance.
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Affiliation(s)
- Charles Q Li
- Department of Radiology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
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Magland JF, Jones CE, Leonard MB, Wehrli FW. Retrospective 3D registration of trabecular bone MR images for longitudinal studies. J Magn Reson Imaging 2009; 29:118-26. [PMID: 19097098 DOI: 10.1002/jmri.21551] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
PURPOSE To evaluate an automatic 3D registration algorithm for serial high-resolution images of trabecular bone (TB) in studies designed to evaluate the response of the trabecular architecture to intervention or disease progression. MATERIALS AND METHODS An efficient algorithm for registering high-resolution 3D images of TB is presented. The procedure identifies the six parameters of rigid displacement between two scans performed at different timepoints. By assuming a relatively small through-plane rotation, considerable time is saved by combining the results of a collection of regional 2D registrations throughout the TB region of interest (ROI). The algorithm was applied to 26 pairs of MR images acquired 6 months apart. Reproducibility of local TB structural parameters (plate, rod, and junction density) computed in manually selected regions were compared between baseline and registered follow-up images. RESULTS All 26 registrations were completed successfully in less than 30 seconds per image pair. The resampled follow-up images agreed with baseline to around one pixel throughout the volume at 137 x 137 x 410 microm(3) image resolution. Structural parameters in each region correlated well from baseline to follow-up with intraclass correlation coefficients ranging between 85%-97% for TB plate density. Interregional variations in the parameters were large as compared with intraregion reproducibility. CONCLUSION The proposed algorithm was successful in automatically registering baseline and follow-up TB images in a translational study, and may be useful in regional analyses in longitudinal MR studies of TB architecture.
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Affiliation(s)
- Jeremy F Magland
- Department of Radiology, University of Pennsylvania Health System, Philadelphia, Pennsylvania, USA.
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Magland JF, Wehrli FW. Trabecular bone structure analysis in the limited spatial resolution regime of in vivo MRI. Acad Radiol 2008; 15:1482-93. [PMID: 19000865 DOI: 10.1016/j.acra.2008.05.015] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2008] [Revised: 05/13/2008] [Accepted: 05/14/2008] [Indexed: 10/21/2022]
Abstract
RATIONALE AND OBJECTIVES To develop a method for processing and visualization of trabecular bone networks on the basis of magnetic resonance (MR) images acquired in the limited spatial resolution regime of in vivo imaging at which trabecular thickness is comparable to voxel size. MATERIALS AND METHODS A sequence of processing steps for analyzing the topologic structure of trabecular bone networks is presented and evaluated using three types of datasets: images of synthetic structures with various levels of superimposed Gaussian noise, micro-computed tomographic images of human trabecular bone downsampled to in vivo resolution, and in vivo micro-MR images from a prior longitudinal study investigating the structural implications of testosterone treatment of hypogonadal men. The simulated images were analyzed at a voxel size of 150 microm(3), the clinical MR image data had been acquired with 137 x 137 x 410 microm(3) voxel size. The technique is a modification to the virtual bone biopsy processing chain that involves a sinc convolution step immediately preceding binarization, and employs the Manzanera-Bernard thinning algorithm for obtaining the three-dimensional skeleton before topologic classification. The detectability of plate and rod bone elements was also analyzed theoretically. RESULTS As compared with previously published techniques, the approach produced a more accurate bone skeleton in the micro-computed tomographic and simulation experiments, with clear improvement in preservation of rod and plate elements. Simulations suggest that rods are detectable down to a diameter of approximately 50% of the MR image voxel length, whereas plates can be detected at thicknesses of 20% or more of voxel length. For in vivo studies, it was shown that the method could recover the treatment response in terms of the ensuing topologic changes in patients undergoing antiresorptive treatment. CONCLUSIONS The algorithm for processing of in vivo micro-MR images of trabecular bone is superior to prior approaches in preserving the topology of the network in the presence of noise.
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Díez-Pérez A, González-Macías J. Inadequate responders to osteoporosis treatment: proposal for an operational definition. Osteoporos Int 2008; 19:1511-6. [PMID: 18546031 DOI: 10.1007/s00198-008-0659-2] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2007] [Accepted: 05/12/2008] [Indexed: 11/27/2022]
Abstract
UNLABELLED The concept of inadequate response to osteoporosis treatment is not clear. In the literature several criteria have been used. We propose an operational definition of an inadequate responder based on the changes observed in bone mineral density and incident fractures while on therapy. INTRODUCTION Fractures may occur in compliant patients even while on active treatment. These cases have been defined as inadequate responders (IR). METHODS We reviewed the basis for this concept and propose an operational definition for IR. RESULTS Good compliance and adequate calcium and vitamin D supplementation are the first requirement. The second requirement is a treatment period of at least 1 year, since before that time treatment may not have been fully effective. Fractures are the gold standard for measuring efficacy and changes in bone density and turnover markers may be surrogates. We propose classifying patient response as: Inadequate--incident fracture and a decrease in BMD greater than a significant change (Trend Assessment Margin or TAM); Possibly inadequate--incident fracture or a decrease in BMD greater than a significant change (TAM); and Appropriate--no fracture and no decrease in BMD greater than a significant change (TAM). Additional criteria (biochemical markers, bone quality parameters) may be taken into account. CONCLUSION A wide consensus on the IR concept is required given its clinical, regulatory, and reimbursement implications.
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Affiliation(s)
- A Díez-Pérez
- Hospital del Mar, Autonomous University of Barcelona, URFOA-IMIM, RETICEF, Barcelona, Spain.
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In vivo magnetic resonance detects rapid remodeling changes in the topology of the trabecular bone network after menopause and the protective effect of estradiol. J Bone Miner Res 2008; 23:730-40. [PMID: 18251704 PMCID: PMC2674544 DOI: 10.1359/jbmr.080108] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
INTRODUCTION Estrogen depletion after menopause is accompanied by bone loss and architectural deterioration of trabecular bone. The hypothesis underlying this work is that the microMRI-based virtual bone biopsy can capture the temporal changes of scale and topology of the trabecular network and that estrogen supplementation preserves the integrity of the trabecular network. MATERIALS AND METHODS Subjects studied were early postmenopausal women, 45-55 yr of age (N = 65), of whom 32 were on estrogen (estradiol group), and the remainder were not (control group). Early menopause was defined by amenorrhea for 6-24 mo and elevated serum follicle-stimulating hormone (FSH) concentration. The subjects were evaluated with three imaging modalities at baseline and 12 and 24 mo to determine the temporal changes in trabecular and cortical architecture and density. microMRI of the distal radius and tibia was performed at 137 x 137 x 410-microm(3) voxel size. The resulting bone volume fraction maps were Fourier interpolated to a final voxel size of 45.7 x 45.7 x 136.7 microm(3), binarized, skeletonized, and subjected to 3D digital topological analysis (DTA). Skeletonization converts trabecular rods to curves and plates to surfaces. Parameters quantifying scale included BV/TV, whereas DTA parameters included the volume densities of curves (C) and surface (S)-type voxels, as well as composite parameters: the surface/curve ratio (S/C), and erosion index (EI, ratio of the sum of parameters expected to increase with osteoclastic resorption divided by the sum of those expected to decrease). For comparison, pQCT of the same peripheral locations was conducted, and trabecular density and cortical structural parameters were measured. Areal BMD of the lumbar vertebrae and hip was also measured. RESULTS Substantial changes in trabecular architecture of the distal tibia, in particular as they relate to topology of the network, were detected after 12 mo in the control group. S/C decreased 5.6% (p < 0.0005), and EI increased 7.1% (p < 0.0005). Most curve- and profile-type voxels (representative of trabecular struts), increased significantly (p < 0.001). Curve and profile edges resulting from disconnection of rod-like trabeculae increased by 9.8% and 5.1% (p = 0.0001 and <0.001, respectively). Similarly, DXA BMD in the spine and hip decreased 2.6% and 1.3% (p < 0.0001 and <0.005, respectively), and pQCT cortical area decreased 3.6% (p = 0.0001). However, neither trabecular density nor BV/TV changed. Furthermore, none of the parameters measured in the estradiol group were significantly different after 12 mo. Substantial differences in the mean changes from baseline between the estradiol treatment and control groups, in particular after 24 mo, were observed, with relative group differences as large as 13% (S/C, p = 0.005), and the relative changes in the two groups had the opposite sign for most parameters. The observed temporal alterations in architecture are consistent with remodeling changes that involve gradual conversion of plate-like to rod-like trabecular bone along with disconnection of trabecular elements, even in the absence of a net loss of trabecular bone. The high-resolution 3D rendered images provide direct evidence of the above remodeling changes in individual subjects. The radius structural data indicated similar trends but offered no definitive conclusions. CONCLUSIONS The short-term temporal changes in trabecular architecture after menopause, and the protective effects of estradiol ensuring maintenance of a more plate-like TB architecture, reported here, have not previously been observed in vivo. This work suggests that MRI-based in vivo micromorphometry of trabecular bone has promise as a tool for monitoring osteoporosis treatment.
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