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Gabel L, Kent K, Hosseinitabatabaei S, Burghardt AJ, Leonard MB, Rauch F, Willie BM. Recommendations for High-resolution Peripheral Quantitative Computed Tomography Assessment of Bone Density, Microarchitecture, and Strength in Pediatric Populations. Curr Osteoporos Rep 2023; 21:609-623. [PMID: 37428435 PMCID: PMC10543577 DOI: 10.1007/s11914-023-00811-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 06/22/2023] [Indexed: 07/11/2023]
Abstract
PURPOSE OF REVIEW The purpose of this review is to summarize current approaches and provide recommendations for imaging bone in pediatric populations using high-resolution peripheral quantitative computed tomography (HR-pQCT). RECENT FINDINGS Imaging the growing skeleton is challenging and HR-pQCT protocols are not standardized across centers. Adopting a single-imaging protocol for all studies is unrealistic; thus, we present three established protocols for HR-pQCT imaging in children and adolescents and share advantages and disadvantages of each. Limiting protocol variation will enhance the uniformity of results and increase our ability to compare study results between different research groups. We outline special cases along with tips and tricks for acquiring and processing scans to minimize motion artifacts and account for growing bone. The recommendations in this review are intended to help researchers perform HR-pQCT imaging in pediatric populations and extend our collective knowledge of bone structure, architecture, and strength during the growing years.
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Affiliation(s)
- L Gabel
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, 2500 University Dr NW, Calgary, AB, T2N 1N4, Canada.
- McCaig Institute for Bone and Joint Health and Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, Canada.
| | - K Kent
- Department of Pediatrics, Stanford School of Medicine, Stanford, CA, USA
| | - S Hosseinitabatabaei
- Research Centre, Shriners Hospital for Children-Canada, Montreal, Canada
- Department of Biomedical Engineering, McGill University, Montreal, Canada
| | - A J Burghardt
- Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA, USA
| | - M B Leonard
- Department of Pediatrics, Stanford School of Medicine, Stanford, CA, USA
| | - F Rauch
- Research Centre, Shriners Hospital for Children-Canada, Montreal, Canada
- Department of Pediatrics, McGill University, Montreal, Canada
| | - B M Willie
- Research Centre, Shriners Hospital for Children-Canada, Montreal, Canada
- Department of Biomedical Engineering, McGill University, Montreal, Canada
- Faculty of Dental Medicine and Oral Health Sciences, McGill University, Montreal, Canada
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Whittier DE, Boyd SK, Burghardt AJ, Paccou J, Ghasem-Zadeh A, Chapurlat R, Engelke K, Bouxsein ML. Guidelines for the assessment of bone density and microarchitecture in vivo using high-resolution peripheral quantitative computed tomography. Osteoporos Int 2020; 31:1607-1627. [PMID: 32458029 PMCID: PMC7429313 DOI: 10.1007/s00198-020-05438-5] [Citation(s) in RCA: 159] [Impact Index Per Article: 39.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Accepted: 04/23/2020] [Indexed: 12/29/2022]
Abstract
INTRODUCTION The application of high-resolution peripheral quantitative computed tomography (HR-pQCT) to assess bone microarchitecture has grown rapidly since its introduction in 2005. As the use of HR-pQCT for clinical research continues to grow, there is an urgent need to form a consensus on imaging and analysis methodologies so that studies can be appropriately compared. In addition, with the recent introduction of the second-generation HrpQCT, which differs from the first-generation HR-pQCT in scan region, resolution, and morphological measurement techniques, there is a need for guidelines on appropriate reporting of results and considerations as the field adopts newer systems. METHODS A joint working group between the International Osteoporosis Foundation, American Society of Bone and Mineral Research, and European Calcified Tissue Society convened in person and by teleconference over several years to produce the guidelines and recommendations presented in this document. RESULTS An overview and discussion is provided for (1) standardized protocol for imaging distal radius and tibia sites using HR-pQCT, with the importance of quality control and operator training discussed; (2) standardized terminology and recommendations on reporting results; (3) factors influencing accuracy and precision error, with considerations for longitudinal and multi-center study designs; and finally (4) comparison between scanner generations and other high-resolution CT systems. CONCLUSION This article addresses the need for standardization of HR-pQCT imaging techniques and terminology, provides guidance on interpretation and reporting of results, and discusses unresolved issues in the field.
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Affiliation(s)
- D E Whittier
- McCaig Institute for Bone and Joint Health, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
- Department of Radiology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - S K Boyd
- McCaig Institute for Bone and Joint Health, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
- Department of Radiology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - A J Burghardt
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA, USA
| | - J Paccou
- Department of Rheumatology, MABlab UR 4490, CHU Lille, Univ. Lille, 59000, Lille, France
| | - A Ghasem-Zadeh
- Departments of Endocrinology and Medicine, Austin Health, The University of Melbourne, Melbourne, Australia
| | - R Chapurlat
- INSERM UMR 1033, Université de Lyon, Lyon, France
- Hôpital Edouard Herriot, Hospice Civils de Lyon, Lyon, France
| | - K Engelke
- Department of Medicine 3, FAU University Erlangen-Nürnberg and Universitätsklinikum Erlangen, Erlangen, Germany
- Bioclinica, Inc., Hamburg, Germany
| | - M L Bouxsein
- Center for Advanced Orthopedic Studies, Beth Israel Deaconess Medical Center, Boston, MA, USA.
- Harvard Medical School, Boston, MA, USA.
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Ensrud KE, Vo TN, Burghardt AJ, Schousboe JT, Cauley JA, Taylor BC, Hoffman AR, Orwoll ES, Lane NE, Langsetmo L. Weight loss in men in late life and bone strength and microarchitecture: a prospective study. Osteoporos Int 2018; 29:1549-1558. [PMID: 29572622 PMCID: PMC6035779 DOI: 10.1007/s00198-018-4489-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Accepted: 03/12/2018] [Indexed: 01/22/2023]
Abstract
UNLABELLED Weight loss in men in late life was associated with lower bone strength. In contrast, weight gain was not associated with a commensurate increase in bone strength. Future studies should measure concurrent changes in weight and parameters of bone strength and microarchitecture and evaluate potential causal pathways underlying these associations. INTRODUCTION Our aim was to determine associations of weight loss with bone strength and microarchitecture. METHODS We used data from 1723 community-dwelling men (mean age 84.5 years) who attended the MrOS study Year (Y) 14 exam and had high-resolution peripheral quantitative computed tomography (HR-pQCT) scans at ≥ 1 skeletal sites (distal tibia, distal radius, or diaphyseal tibia). Weight change from Y7 to Y14 exams (mean 7.3 years between exams) was classified as moderate weight loss (loss ≥ 10%), mild weight loss (loss 5 to < 10%), stable weight (< 5% change), or weight gain (gain ≥ 5%). Mean HR-pQCT parameters (95%CI) were calculated by weight change category using linear regression models adjusted for age, race, site, health status, body mass index, limb length, and physical activity. The primary outcome measure was estimated failure load. RESULTS There was a nonlinear association of weight change with failure load at each skeletal site with different associations for weight loss vs. weight gain (p < 0.03). Failure load and total bone mineral density (BMD) at distal sites were lower with greater weight loss with 7.0-7.6% lower failure loads and 4.3-5.8% lower BMDs among men with moderate weight loss compared to those with stable weight (p < 0.01, both comparisons). Cortical, but not trabecular, BMDs at distal sites were lower with greater weight loss. Greater weight loss was associated with lower cortical thickness at all three skeletal sites. CONCLUSION Weight loss in men in late life is associated with lower peripheral bone strength and total BMD with global measures reflecting cortical but not trabecular parameters.
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Affiliation(s)
- K E Ensrud
- Department of Medicine, University of Minnesota, Minneapolis, MN, USA.
- Division of Epidemiology & Community Health, University of Minnesota, Minneapolis, MN, USA.
- Center for Chronic Disease Outcomes Research, VA Health Care System, One Veterans Drive (111-0), Minneapolis, MN, 55417, USA.
| | - T N Vo
- Division of Epidemiology & Community Health, University of Minnesota, Minneapolis, MN, USA
| | - A J Burghardt
- Department of Radiology & Biomedical Imaging, University of California, San Francisco, CA, USA
| | - J T Schousboe
- HealthPartners Institute, Bloomington, MN, USA
- Division of Health Policy and Management, University of Minnesota, Minneapolis, MN, USA
| | - J A Cauley
- Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - B C Taylor
- Department of Medicine, University of Minnesota, Minneapolis, MN, USA
- Division of Epidemiology & Community Health, University of Minnesota, Minneapolis, MN, USA
- Center for Chronic Disease Outcomes Research, VA Health Care System, One Veterans Drive (111-0), Minneapolis, MN, 55417, USA
| | - A R Hoffman
- Department of Medicine, Stanford University, Stanford, CA, USA
| | - E S Orwoll
- Bone and Mineral Unit, Oregon Health & Science University, Portland, OR, USA
| | - N E Lane
- Department of Medicine, University of California, Davis, CA, USA
| | - L Langsetmo
- Division of Epidemiology & Community Health, University of Minnesota, Minneapolis, MN, USA
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Langsetmo L, Shikany JM, Burghardt AJ, Cawthon PM, Orwoll ES, Cauley JA, Taylor BC, Schousboe JT, Bauer DC, Vo TN, Ensrud KE. High dairy protein intake is associated with greater bone strength parameters at the distal radius and tibia in older men: a cross-sectional study. Osteoporos Int 2018; 29:69-77. [PMID: 29063213 PMCID: PMC5772967 DOI: 10.1007/s00198-017-4261-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Accepted: 10/09/2017] [Indexed: 12/17/2022]
Abstract
UNLABELLED Dairy protein but not plant protein was associated with bone strength of the radius and tibia in older men. These results are consistent with previous results in women and support similar findings related to fracture outcomes. Bone strength differences were largely due to thickness and area of the bone cortex. INTRODUCTION Our objective was to determine the association of protein intake by source (dairy, non-dairy animal, plant) with bone strength and bone microarchitecture among older men. METHODS We used data from 1016 men (mean 84.3 years) who attended the Year 14 exam of the Osteoporotic Fractures in Men (MrOS) study, completed a food frequency questionnaire (500-5000 kcal/day), were not taking androgen or androgen agonists, and had high-resolution peripheral quantitative computed tomography (HR-pQCT) scans of the distal radius and distal or diaphyseal tibia. Protein was expressed as percentage of total energy intake (TEI); mean ± SD for TEI = 1548 ± 607 kcal/day and for total protein = 16.2 ± 2.9%TEI. We used linear regression with standardized HR-pQCT parameters as dependent variables and adjusted for age, limb length, center, education, race/ethnicity, marital status, smoking, alcohol intake, physical activity level, corticosteroids use, supplement use (calcium and vitamin D), and osteoporosis medications. RESULTS Higher dairy protein intake was associated with higher estimated failure load at the distal radius and distal tibia [radius effect size = 0.17 (95% CI 0.07, 0.27), tibia effect size = 0.13 (95% CI 0.03, 0.23)], while higher non-dairy animal protein was associated with higher failure load at only the distal radius. Plant protein intake was not associated with failure load at any site. CONCLUSION The association between protein intake and bone strength varied by source of protein. These results support a link between dairy protein intake and skeletal health, but an intervention study is needed to evaluate causality.
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Affiliation(s)
- L Langsetmo
- Division of Epidemiology and Community Health, University of Minnesota, 1300 S. 2nd St., Suite 300, Minneapolis, MN, 55454, USA.
| | - J M Shikany
- Division of Preventive Medicine, School of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - A J Burghardt
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA, USA
| | - P M Cawthon
- California Pacific Medical Center Research Institute, San Francisco, CA, USA
- Department of Epidemiology and Biostatistics, University of California, San Francisco, CA, USA
| | - E S Orwoll
- Bone and Mineral Unit, Oregon Health Sciences University, Portland, OR, USA
| | - J A Cauley
- Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - B C Taylor
- Division of Epidemiology and Community Health, University of Minnesota, 1300 S. 2nd St., Suite 300, Minneapolis, MN, 55454, USA
- Department of Medicine, University of Minnesota, Minneapolis, MN, USA
- Center for Chronic Disease Outcomes Research, Minneapolis VA Health Care System, Minneapolis, MN, USA
| | - J T Schousboe
- Park Nicollet Clinic and HealthPartners Institute, Bloomington, MN, USA
- Division of Health Policy and Management, University of Minnesota, Minneapolis, MN, USA
| | - D C Bauer
- Departments of Medicine, University of California San Francisco, San Francisco, CA, USA
| | - T N Vo
- Division of Epidemiology and Community Health, University of Minnesota, 1300 S. 2nd St., Suite 300, Minneapolis, MN, 55454, USA
| | - K E Ensrud
- Division of Epidemiology and Community Health, University of Minnesota, 1300 S. 2nd St., Suite 300, Minneapolis, MN, 55454, USA
- Department of Medicine, University of Minnesota, Minneapolis, MN, USA
- Center for Chronic Disease Outcomes Research, Minneapolis VA Health Care System, Minneapolis, MN, USA
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Bonaretti S, Majumdar S, Lang TF, Khosla S, Burghardt AJ. The comparability of HR-pQCT bone measurements is improved by scanning anatomically standardized regions. Osteoporos Int 2017; 28:2115-2128. [PMID: 28391447 PMCID: PMC5526099 DOI: 10.1007/s00198-017-4010-7] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Accepted: 03/13/2017] [Indexed: 12/16/2022]
Abstract
UNLABELLED We investigated the sensitivity of distal bone density, structure, and strength measurements by high-resolution peripheral quantitative computed tomography (HR-pQCT) to variability in limb length. Our results demonstrate that HR-pQCT should be performed at a standard %-of-total-limb-length to avoid substantial measurement bias in population study comparisons and the evaluation of individual skeletal status in a clinical context. INTRODUCTION High-resolution peripheral quantitative computed tomography (HR-pQCT) measures of bone do not account for anatomic variability in bone length: a 1-cm volume is acquired at a fixed offset from an anatomic landmark. Our goal was to evaluate HR-pQCT measurement variability introduced by imaging fixed vs. proportional volumes and to propose a standard protocol for relative anatomic positioning. METHODS Double-length (2-cm) scans were acquired in 30 adults. We compared measurements from 1-cm sub-volumes located at the default fixed offset, and the average %-of-length offset. The average position corresponded to 4.0% ± 1.1 mm for radius, and 7.2% ± 2.2 mm for tibia. We calculated the RMS difference in bone parameters and T-scores to determine the measurement variability related to differences in limb length. We used anthropometric ratios to estimate the mean limb length for published HR-pQCT reference data, and then calculated mean %-of-length offsets. RESULTS Variability between fixed vs. relative scan positions was highest in the radius, and for cortical bone in general (RMS difference Ct.Th = 19.5%), while individuals had T-score differentials as high as +3.0 SD (radius Ct.BMD). We estimated that average scan position for published HR-pQCT reference data corresponded to 4.0% at the radius, and 7.3% at tibia. CONCLUSION Variability in limb length introduces significant bias to HR-pQCT measures, confounding cross-sectional analyses and limiting the clinical application for individual assessment of skeletal status. We propose to standardize scan positioning using 4.0 and 7.3% of total bone length for the distal radius and tibia, respectively.
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Affiliation(s)
- S Bonaretti
- Musculoskeletal Quantitative Imaging Research Group, Department of Radiology & Biomedical Imaging, University of California, QB3 Building, Suite 203, 1700 4th St, San Francisco, CA, 94158, USA
- Department of Radiology, Stanford University, Stanford, CA, USA
| | - S Majumdar
- Musculoskeletal Quantitative Imaging Research Group, Department of Radiology & Biomedical Imaging, University of California, QB3 Building, Suite 203, 1700 4th St, San Francisco, CA, 94158, USA
| | - T F Lang
- Musculoskeletal Quantitative Imaging Research Group, Department of Radiology & Biomedical Imaging, University of California, QB3 Building, Suite 203, 1700 4th St, San Francisco, CA, 94158, USA
| | - S Khosla
- Division of Endocrinology, Metabolism and Nutrition, Department of Internal Medicine, College of Medicine, Mayo Clinic, Rochester, MN, USA
| | - A J Burghardt
- Musculoskeletal Quantitative Imaging Research Group, Department of Radiology & Biomedical Imaging, University of California, QB3 Building, Suite 203, 1700 4th St, San Francisco, CA, 94158, USA.
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Bonaretti S, Vilayphiou N, Chan CM, Yu A, Nishiyama K, Liu D, Boutroy S, Ghasem-Zadeh A, Boyd SK, Chapurlat R, McKay H, Shane E, Bouxsein ML, Black DM, Majumdar S, Orwoll ES, Lang TF, Khosla S, Burghardt AJ. Operator variability in scan positioning is a major component of HR-pQCT precision error and is reduced by standardized training. Osteoporos Int 2017; 28:245-257. [PMID: 27475931 PMCID: PMC5568957 DOI: 10.1007/s00198-016-3705-5] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Accepted: 07/07/2016] [Indexed: 02/02/2023]
Abstract
UNLABELLED In this study, we determined that operator positioning precision contributes significant measurement error in high-resolution peripheral quantitative computed tomography (HR-pQCT). Moreover, we developed software to quantify intra- and inter-operator variability and demonstrated that standard positioning training (now available as a web-based application) can significantly reduce inter-operator variability. INTRODUCTION HR-pQCT is increasingly used to assess bone quality, fracture risk, and anti-fracture interventions. The contribution of the operator has not been adequately accounted in measurement precision. Operators acquire a 2D projection ("scout view image") and define the region to be scanned by positioning a "reference line" on a standard anatomical landmark. In this study, we (i) evaluated the contribution of positioning variability to in vivo measurement precision, (ii) measured intra- and inter-operator positioning variability, and (iii) tested if custom training software led to superior reproducibility in new operators compared to experienced operators. METHODS To evaluate the operator in vivo measurement precision, we compared precision errors calculated in 64 co-registered and non-co-registered scan-rescan images. To quantify operator variability, we developed software that simulates the positioning process of the scanner's software. Eight experienced operators positioned reference lines on scout view images designed to test intra- and inter-operator reproducibility. Finally, we developed modules for training and evaluation of reference line positioning. We enrolled six new operators to participate in a common training, followed by the same reproducibility experiments performed by the experienced group. RESULTS In vivo precision errors were up to threefold greater (Tt.BMD and Ct.Th) when variability in scan positioning was included. The inter-operator precision errors were significantly greater than the short-term intra-operator precision (p < 0.001). New trained operators achieved comparable intra-operator reproducibility to experienced operators and lower inter-operator reproducibility (p < 0.001). Precision errors were significantly greater for the radius than for the tibia. CONCLUSION Operator reference line positioning contributes significantly to in vivo measurement precision and is significantly greater for multi-operator datasets. Inter-operator variability can be significantly reduced using a systematic training platform, now available online ( http://webapps.radiology.ucsf.edu/refline/ ).
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Affiliation(s)
- S Bonaretti
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA, USA.
- Department of Radiology, Stanford University, Stanford, CA, USA.
| | | | - C M Chan
- University of California Berkeley, Berkeley, CA, USA
| | - A Yu
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA, USA
| | - K Nishiyama
- Division of Endocrinology, Department of Medicine, Columbia University Medical Center, New York, NY, USA
| | - D Liu
- University of British Columbia, Vancouver, BC, Canada
| | - S Boutroy
- INSERM UMR 1033, Université de Lyon, Lyon, France
| | - A Ghasem-Zadeh
- Department of Medicine, Austin Health, University of Melbourne, Melbourne, Australia
| | - S K Boyd
- Department of Radiology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - R Chapurlat
- INSERM UMR 1033, Université de Lyon, Lyon, France
| | - H McKay
- University of British Columbia, Vancouver, BC, Canada
| | - E Shane
- Division of Endocrinology, Department of Medicine, Columbia University Medical Center, New York, NY, USA
| | - M L Bouxsein
- Center for Advanced Orthopaedic Studies, Beth Israel Deaconess Medical Center, Boston, MA, USA
| | - D M Black
- Department of Epidemiology and Biostatistics, University of California, San Francisco, CA, USA
| | - S Majumdar
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA, USA
| | - E S Orwoll
- Division of Endocrinology, Bone and Mineral Unit, Oregon Health & Science University, Portland, OR, USA
| | - T F Lang
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA, USA
| | - S Khosla
- Division of Endocrinology, Metabolism and Nutrition, Department of Internal Medicine, College of Medicine, Mayo Clinic, Rochester, MN, USA
| | - A J Burghardt
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA, USA
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Heilmeier U, Cheng K, Pasco C, Parrish R, Nirody J, Patsch JM, Zhang CA, Joseph GB, Burghardt AJ, Schwartz AV, Link TM, Kazakia G. Cortical bone laminar analysis reveals increased midcortical and periosteal porosity in type 2 diabetic postmenopausal women with history of fragility fractures compared to fracture-free diabetics. Osteoporos Int 2016; 27:2791-2802. [PMID: 27154435 PMCID: PMC6687459 DOI: 10.1007/s00198-016-3614-7] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Accepted: 04/20/2016] [Indexed: 02/08/2023]
Abstract
UNLABELLED We investigated the characteristics and spatial distribution of cortical bone pores in postmenopausal women with type 2 diabetes (T2D). High porosity in the midcortical and periosteal layers in T2D subjects with fragility fractures suggests that these cortical zones might be particularly susceptible to T2D-induced toxicity and may reflect cortical microangiopathy. INTRODUCTION Elevated cortical porosity is regarded as one of the main contributors to the high skeletal fragility in T2D. However, to date, it remains unclear if diabetic cortical porosity results from vascular cortical changes or from an expansion in bone marrow space. Here, we used a novel cortical laminar analysis technique to investigate the characteristics and spatial radial distribution of cortical pores in a T2D group with prior history of fragility fractures (DMFx, assigned high-risk group) and a fracture-free T2D group (DM, assigned low-risk group) and to compare their results to non-diabetic controls with (Fx) and without fragility fractures (Co). METHODS Eighty postmenopausal women (n = 20/group) underwent high-resolution peripheral quantitative computed tomography (HR-pQCT) of the distal tibia and radius. Cortical bone was divided into three layers of equal width including an endosteal, midcortical, and periosteal layer. Within each layer, total pore area (TPA), total pore number (TPN), and average pore area (APA) were calculated. Statistical analysis employed Mann-Whitney tests and ANOVA with post hoc tests. RESULTS Compared to the DM group, DMFx subjects exhibited +90 to +365 % elevated global porosity (p = 0.001). Cortical laminar analysis revealed that this increased porosity was for both skeletal sites confined to the midcortical layer, followed by the periosteal layer (midcortical +1327 % TPA, p ≤ 0.001, periosteal +634 % TPA, p = 0.002), and was associated in both layers and skeletal sites with high TPN (+430 % TPN, p < 0.001) and high APA (+71.5 % APA, p < 0.001). CONCLUSION High porosity in the midcortical and periosteal layers in the high-risk T2D group suggests that these cortical zones might be particularly susceptible to T2D-induced toxicity and may reflect cortical microangiopathy.
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Affiliation(s)
- U Heilmeier
- Musculoskeletal Quantitative Imaging Research Group, Department of Radiology & Biomedical Imaging, University of California San Francisco, 185 Berry Street, San Francisco, CA, 94158, USA.
| | - K Cheng
- Department of Bioengineering, University of California Berkeley, 306 Stanley Hall, Berkeley, CA, 94720, USA
| | - C Pasco
- Department of Bioengineering, University of California Berkeley, 306 Stanley Hall, Berkeley, CA, 94720, USA
| | - R Parrish
- Department of Bioengineering, University of California Berkeley, 306 Stanley Hall, Berkeley, CA, 94720, USA
| | - J Nirody
- Biophysics Graduate Group, University of California Berkeley, 574 Stanley Hall, MC 3220, Berkeley, CA, 94720, USA
| | - J M Patsch
- Musculoskeletal Quantitative Imaging Research Group, Department of Radiology & Biomedical Imaging, University of California San Francisco, 185 Berry Street, San Francisco, CA, 94158, USA
- Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria
| | - C A Zhang
- Department of Epidemiology and Biostatistics, University of California San Francisco, 550 16th Street, San Francisco, CA, 94158, USA
| | - G B Joseph
- Musculoskeletal Quantitative Imaging Research Group, Department of Radiology & Biomedical Imaging, University of California San Francisco, 185 Berry Street, San Francisco, CA, 94158, USA
| | - A J Burghardt
- Musculoskeletal Quantitative Imaging Research Group, Department of Radiology & Biomedical Imaging, University of California San Francisco, 185 Berry Street, San Francisco, CA, 94158, USA
| | - A V Schwartz
- Department of Epidemiology and Biostatistics, University of California San Francisco, 550 16th Street, San Francisco, CA, 94158, USA
| | - T M Link
- Musculoskeletal Quantitative Imaging Research Group, Department of Radiology & Biomedical Imaging, University of California San Francisco, 185 Berry Street, San Francisco, CA, 94158, USA
| | - G Kazakia
- Musculoskeletal Quantitative Imaging Research Group, Department of Radiology & Biomedical Imaging, University of California San Francisco, 185 Berry Street, San Francisco, CA, 94158, USA
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Bonaretti S, Carpenter RD, Saeed I, Burghardt AJ, Yu L, Bruesewitz M, Khosla S, Lang T. Novel anthropomorphic hip phantom corrects systemic interscanner differences in proximal femoral vBMD. Phys Med Biol 2016; 59:7819-34. [PMID: 25419618 DOI: 10.1088/0031-9155/59/24/7819] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Quantitative computed tomography (QCT) is increasingly used in osteoporosis studies to assess volumetric bone mineral density (vBMD), bone quality and strength. However, QCT is confronted by technical issues in the clinical research setting, such as potentially confounding effects of body size on vBMD measurements and lack of standard approaches to scanner cross-calibration, which affects measurements of vBMD in multicenter settings. In this study, we addressed systematic inter-scanner differences and subject-dependent body size errors using a novel anthropomorphic hip phantom, containing a calibration hip to estimate correction equations, and a contralateral test hip to assess the quality of the correction. We scanned this phantom on four different scanners and we applied phantom-derived corrections to in vivo images of 16 postmenopausal women scanned on two scanners. From the phantom study, we found that vBMD decreased with increasing phantom size in three of four scanners and that inter-scanner variations increased with increasing phantom size. In the in vivo study, we observed that inter-scanner corrections reduced systematic inter-scanner mean vBMD differences but that the inter-scanner precision error was still larger than expected from known intra-scanner precision measurements. In conclusion, inter-scanner corrections and body size influence should be considered when measuring vBMD from QCT images.
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Affiliation(s)
- S Bonaretti
- Musculoskeletal Quantitative Imaging Research Group, Department of Radiology and Biomedical Imaging, University of California, 185 Berry Street, Lobby 6, Suite 350, San Francisco, CA 94107, USA
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Heilmeier U, Carpenter DR, Patsch JM, Harnish R, Joseph GB, Burghardt AJ, Baum T, Schwartz AV, Lang TF, Link TM. Volumetric femoral BMD, bone geometry, and serum sclerostin levels differ between type 2 diabetic postmenopausal women with and without fragility fractures. Osteoporos Int 2015; 26:1283-93. [PMID: 25582311 DOI: 10.1007/s00198-014-2988-7] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Accepted: 11/12/2014] [Indexed: 12/14/2022]
Abstract
UNLABELLED While type 2 diabetes (T2D) is associated with higher skeletal fragility, specific risk stratification remains incompletely understood. We found volumetric bone mineral density, geometry, and serum sclerostin differences between low-fracture risk and high-fracture risk T2D women. These features might help identify T2D individuals at high fracture risk in the future. INTRODUCTION Diabetic bone disease, an increasingly recognized complication of type 2 diabetes mellitus (T2D), is associated with high skeletal fragility. Exactly which T2D individuals are at higher risk for fracture, however, remains incompletely understood. Here, we analyzed volumetric bone mineral density (vBMD), geometry, and serum sclerostin levels in two specific T2D subsets with different fracture risk profiles. We examined a T2D group with prior history of fragility fractures (DMFx, assigned high-risk group) and a fracture-free T2D group (DM, assigned low-risk group) and compared their results to nondiabetic controls with (Fx) and without fragility fractures (Co). METHODS Eighty postmenopausal women (n = 20 per group) underwent quantitative computed tomography (QCT) to compute vBMD and bone geometry of the proximal femur. Additionally, serum sclerostin, vitamin D, parathyroid hormone (PTH), HbA1c, and glomerular filtration rate (GFR) levels were measured. Statistical analyses employed linear regression models. RESULTS DMFx subjects exhibited up to 33 % lower femoral neck vBMD than DM subjects across all femoral sites (-19 % ≤ ΔvBMD ≤ -33 %, 0.008 ≤ p ≤0.021). Additionally, DMFx subjects showed significantly thinner cortices (-6 %, p = 0.046) and a trend toward larger bone volume (+10 %, p = 0.055) relative to DM women and higher serum sclerostin levels when compared to DM (+31.4 %, p = 0.013), Fx (+25.2 %, p = 0.033), and control (+22.4 %, p = 0.028) subjects. CONCLUSION Our data suggest that volumetric bone parameters by QCT and serum sclerostin levels can identify T2D individuals at high risk of fracture and might therefore show promise as clinical tools for fracture risk assessment in T2D. However, future research is needed to establish diabetes-specific QCT- and sclerostin-reference databases.
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Affiliation(s)
- U Heilmeier
- Musculoskeletal Quantitative Imaging Research Group, Department of Radiology & Biomedical Imaging, University of California San Francisco, 185 Berry Street, Lobby 6, Suite 350, San Francisco, CA, 94158, USA,
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10
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Schafer AL, Burghardt AJ, Sellmeyer DE, Palermo L, Shoback DM, Majumdar S, Black DM. Postmenopausal women treated with combination parathyroid hormone (1-84) and ibandronate demonstrate different microstructural changes at the radius vs. tibia: the PTH and Ibandronate Combination Study (PICS). Osteoporos Int 2013; 24:2591-601. [PMID: 23589163 DOI: 10.1007/s00198-013-2349-y] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2012] [Accepted: 02/25/2013] [Indexed: 01/01/2023]
Abstract
SUMMARY In postmenopausal women receiving combination parathyroid hormone (PTH) (1-84) therapy and ibandronate, we evaluated bone microarchitecture and biomechanics using high-resolution peripheral quantitative computed tomography (HR-pQCT). Cortical and trabecular changes were different at the nonweight-bearing radius vs. the weight-bearing tibia, with more favorable overall changes at the tibia. INTRODUCTION PTH therapy and bisphosphonates decrease fracture risk in postmenopausal osteoporosis, but their effects on bone microstructure and strength have not been fully characterized, particularly during combination therapy. PTH increases trabecular bone mineral density (BMD) substantially but may decrease cortical BMD, possibly by stimulating intracortical remodeling. We evaluated bone microarchitecture and biomechanics with HR-pQCT at the radius (a nonweight-bearing site) and tibia (weight bearing) in women receiving combination PTH(1-84) and ibandronate. METHODS Postmenopausal women with low bone mass (n = 43) were treated with 6 months of PTH(1-84) (100 μg/day), either as one 6- or two 3-month courses, in combination with ibandronate (150 mg/month) over 2 years. HR-pQCT was performed before and after therapy. RESULTS Because changes in HR-pQCT parameters did not differ between treatment arms, groups were pooled into one cohort for analysis. Trabecular BMD increased at both radius and tibia (p < 0.01 for each). Cortical thickness and BMD decreased at the radius (p < 0.01), consistent with changes in dual-energy X-ray absorptiometry, while these parameters did not change at the tibia (p ≤ 0.02 for difference between radius and tibia). In contrast, cortical porosity increased at the tibia (p < 0.01) but not radius. Stiffness and failure load decreased at the radius (p < 0.0001) but did not change at the tibia. CONCLUSIONS Cortical and trabecular changes in response to the PTH/ibandronate treatment combinations utilized in this study were different at the nonweight-bearing radius vs. the weight-bearing tibia, with more favorable overall changes at the tibia. Our findings support the possibility that weight bearing may optimize the effects of osteoporosis therapy.
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Affiliation(s)
- A L Schafer
- Endocrine Research Unit, San Francisco Veterans Affairs Medical Center, 4150 Clement Street, 111N, San Francisco, CA, 94121, USA,
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11
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Pialat JB, Burghardt AJ, Sode M, Link TM, Majumdar S. Visual grading of motion induced image degradation in high resolution peripheral computed tomography: impact of image quality on measures of bone density and micro-architecture. Bone 2012; 50:111-8. [PMID: 22019605 DOI: 10.1016/j.bone.2011.10.003] [Citation(s) in RCA: 197] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2011] [Revised: 08/10/2011] [Accepted: 10/05/2011] [Indexed: 11/24/2022]
Abstract
Motion artifacts are a common finding during high-resolution peripheral quantitative computed tomography (HR-pQCT) image acquisitions. To date it is not clear (i) when to repeat an acquisition, (ii) when to exclude a motion-degraded dataset post hoc, and (iii) how motion induced artifacts impact measures of trabecular and cortical parameters. In this study we present inter- and intra-observer reproducibility of a qualitative image quality grading score and report the prevalence of repeat acquisitions in our population. Finally the errors in bone density and micro-architectural parameters estimated from repeat acquisitions with and without motion degradation are presented. The relationship between these errors and the image quality grade is evaluated for each parameter. Repeat acquisitions performed due to operator-observed motion in the reconstructed image occurred for 22.7% of the exams (29.7% radius, 15.7% tibia). Of this subset, 88 exams with repeat acquisitions had at least one acquisition graded 1 (best quality). In this subset, the percent differences in bone density and micro-architecture measures tended to increase as the relative image quality decreased. Micro-architectural parameters were more sensitive to motion compared to geometric and densitometric parameters. These results provide estimates of the error in bone quality measures due to motion artifacts and provide an initial framework for developing standardized quality control criteria for cross-sectional and longitudinal HR-pQCT studies.
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Affiliation(s)
- J B Pialat
- Musculoskeletal Quantitative Imaging Research Group, Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA, USA.
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12
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Jobke B, Muche B, Burghardt AJ, Semler J, Link TM, Majumdar S. Teriparatide in bisphosphonate-resistant osteoporosis: microarchitectural changes and clinical results after 6 and 18 months. Calcif Tissue Int 2011; 89:130-9. [PMID: 21626160 DOI: 10.1007/s00223-011-9500-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/31/2010] [Accepted: 04/13/2011] [Indexed: 10/18/2022]
Abstract
A number of osteoporotic patients under bisphosphonate treatment present persistent fragility fractures and bone loss despite good compliance. The objective of this 18-month prospective study was to investigate the effect of teriparatide [rhPTH(1-34)] in 25 female osteoporotics who were inadequate responders to oral bisphosphonates and to correlate microarchitectural changes in three consecutive iliac crest biopsies measured by micro-computed tomography (μCT) with bone mineral density (BMD) and bone serum markers. Scanned biopsies at baseline (M0), 6 months (M6), and 18 months (M18) demonstrated early significant (P < 0.01) increases in bone volume per tissue volume (+34%) and trabecular number (+14%) at M6 with only moderate changes in most μCT structural parameters between M6 and M18. μCT-measured bone tissue density was significantly decreased at M18, expressing an overall lower degree of tissue mineralization characteristic for new bone formation despite unchanged trabecular thickness due to increased intratrabecular tunneling at M18. μCT results were consistent with serum bone turnover markers, reaching maximal levels of bone alkaline phosphatase and serum β-crosslaps at M6, with subsequent decline until M18. BMD assessed by DXA demonstrated persistent increases at the lumbar spine until M12, whereas no significant change was observed at the hip. Type (alendronate/risedronate) and duration (3.5 ± 4 years) of prior bisphosphonate treatment did not influence outcome on μCT, BMD, or bone marker results. The overall results indicate a positive ceiling effect of teriparatide on bone microarchitecture and bone markers after 6 and 12 months for lumbar spine BMD, with no additional gain until M18 in bisphosphonate nonresponders.
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Affiliation(s)
- B Jobke
- Department of Radiology and Biomedical Imaging, Musculoskeletal and Quantitative Imaging Research Group, University of California-San Francisco, CA, USA.
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13
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Burghardt AJ, Kazakia GJ, Link TM, Majumdar S. Automated simulation of areal bone mineral density assessment in the distal radius from high-resolution peripheral quantitative computed tomography. Osteoporos Int 2009; 20:2017-24. [PMID: 19330422 PMCID: PMC2777210 DOI: 10.1007/s00198-009-0907-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2008] [Accepted: 02/23/2009] [Indexed: 11/30/2022]
Abstract
SUMMARY An automated image processing method is presented for simulating areal bone mineral density measures using high-resolution peripheral quantitative computed tomography (HR-pQCT) in the ultra-distal radius. The accuracy of the method is validated against clinical dual X-ray absorptiometry (DXA). This technique represents a useful reference to gauge the utility of novel 3D quantification methods applied to HR-pQCT in multi-center clinical studies and potentially negates the need for separate forearm DXA measurements. INTRODUCTION Osteoporotic status is primarily assessed by measuring areal bone mineral density (aBMD) using 2D dual X-ray absorptiometry (DXA). However, this technique does not sufficiently explain bone strength and fracture risk. High-resolution peripheral quantitative computed tomography (HR-pQCT) has been introduced as a method to quantify 3D bone microstructure and biomechanics. In this study, an automated method is proposed to simulate aBMD measures from HR-pQCT distal radius images. METHODS A total of 117 subject scans were retrospectively analyzed from two clinical bone quality studies. The distal radius was imaged by HR-pQCT and DXA on one of two devices (Hologic or Lunar). Areal BMD was calculated by simulation from HR-pQCT images (aBMD(sim)) and by standard DXA analysis (aBMD(dxa)). RESULTS The reproducibility of the simulation technique was 1.1% (root mean-squared coefficient of variation). HR-pQCT-based aBMD(sim) correlated strongly to aBMD(dxa) (Hologic: R (2) = 0.82, Lunar: R (2) = 0.87), though aBMD(sim) underestimated aBMD(dxa) for both DXA devices (p < 0.0001). Finally, aBMD(sim) predicted aBMD at the proximal femur and lumbar spine with equal power compared to aBMD(dxa). CONCLUSION The results demonstrate that aBMD can be simulated from HR-pQCT images of the distal radius. This approach has the potential to serve as a surrogate forearm aBMD measure for clinical HR-pQCT studies when axial bone mineral density values are not required.
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Affiliation(s)
- A J Burghardt
- Musculoskeletal Quantitative Imaging Research Group, Department of Radiology and Biomedical Imaging, University of California, San Francisco, QB3 Building, Suite 203, 1700 4th St, San Francisco, CA 94158, USA.
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Kazakia GJ, Burghardt AJ, Cheung S, Majumdar S. Assessment of bone tissue mineralization by conventional x-ray microcomputed tomography: comparison with synchrotron radiation microcomputed tomography and ash measurements. Med Phys 2008; 35:3170-9. [PMID: 18697542 DOI: 10.1118/1.2924210] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Assessment of bone tissue mineral density (TMD) may provide information critical to the understanding of mineralization processes and bone biomechanics. High-resolution three-dimensional assessment of TMD has recently been demonstrated using synchrotron radiation microcomputed tomography (SRmuCT); however, this imaging modality is relatively inaccessible due to the scarcity of SR facilities. Conventional desktop muCT systems are widely available and have been used extensively to assess bone microarchitecture. However, the polychromatic source and cone-shaped beam geometry complicate assessment of TMD by conventional muCT. The goal of this study was to evaluate muCT-based measurement of degree and distribution of tissue mineralization in a quantitative, spatially resolved manner. Specifically, muCT measures of bone mineral content (BMC) and TMD were compared to those obtained by SRmuCT and gravimetric methods. Cylinders of trabecular bone were machined from human femoral heads (n = 5), vertebrae (n = 5), and proximal tibiae (n = 4). Cylinders were imaged in saline on a polychromatic muCT system at an isotropic voxel size of 8 microm. Volumes were reconstructed using beam hardening correction algorithms based on hydroxyapatite (HA)-resin wedge phantoms of 200 and 1200 mg HA/cm3. SRmuCT imaging was performed at an isotropic voxel size of 7.50 microm at the National Synchrotron Light Source. Attenuation values were converted to HA concentration using a linear regression derived by imaging a calibration phantom. Architecture and mineralization parameters were calculated from the image data. Specimens were processed using gravimetric methods to determine ash mass and density, muCT-based BMC values were not affected by altering the beam hardening correction. Volume-averaged TMD values calculated by the two corrections were significantly different (p = 0.008) in high volume fraction specimens only, with the 1200 mg HA/cm3 correction resulting in a 4.7% higher TMD value. MuCT and SRmuCT provided significantly different measurements of both BMC and TMD (p < 0.05). In high volume fraction specimens, muCT with 1200 mg HA/cm3 correctionteg resulted in BMC and TMD values 16.7% and 15.0% lower, respectively, than SRmuCT values. In low volume fraction specimens, muCT with 1200 mg HA/cm3 correction resulted in BMC and TMD values 12.8% and 12.9% lower, respectively, than SRmuCT values. MuCT and SRmuCT values were well-correlated when volume fraction groups were considered individually (BMC R2 = 0.97-1.00; TMD R2 = 0.78-0.99). Ash mass and density were higher than the SRmuCT equivalents by 8.6% in high volume fraction specimens and 10.9% in low volume fraction specimens (p < 0.05). BMC values calculated by tomography were highly correlated with ash mass (ash versus muCT R2 = 0.96-1.00; ash versus SRmuCT R2 = 0.99-1.00). TMD values calculated by tomography were moderately correlated with ash density (ash versus muCT R2 = 0.64-0.72; ash versus SRmuCT R2 = 0.64). Spatially resolved comparisons highlighted substantial geometric nonuniformity in the muCT data, which were reduced (but not eliminated) using the 1200 mg HA/cm3 beam hardening correction, and did not exist in the SRmuCT data. This study represents the first quantitative comparison of muCT mineralization evaluation against SRnuCT and gravimetry. Our results indicate that muCT mineralization measures are underestimated but well-correlated with SRmuCT and gravimetric data, particularly when volume fraction groups are considered individually.
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Affiliation(s)
- G J Kazakia
- Musculoskeletal and Quantitative Imaging Research Group, Department of Radiology, University of California, San Francisco, California 94158, USA.
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15
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Krug R, Carballido-Gamio J, Burghardt AJ, Kazakia G, Hyun BH, Jobke B, Banerjee S, Huber M, Link TM, Majumdar S. Assessment of trabecular bone structure comparing magnetic resonance imaging at 3 Tesla with high-resolution peripheral quantitative computed tomography ex vivo and in vivo. Osteoporos Int 2008; 19:653-61. [PMID: 17992467 DOI: 10.1007/s00198-007-0495-9] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2007] [Accepted: 09/04/2007] [Indexed: 10/22/2022]
Abstract
UNLABELLED In vivo high-resolution peripheral quantitative micro-CT (HR-pQCT) is a new modality for imaging peripheral sites like the distal tibia and the distal radius, providing structural bone parameters. Comparing HR-pQCT with MRI, we found that both modalities are capable of offering meaningful information on trabecular structure. BACKGROUND Magnetic resonance imaging (MRI) has emerged as the leading in vivo method for measuring trabecular bone micro-architecture and providing structural information. Recently, an in vivo HR-pQCT modality was introduced for imaging peripheral sites like the distal tibia and the distal radius, providing structural bone parameters. The goal of this work was to compare and evaluate the performances and in vivo capabilities of HR-pQCT in comparison with MRI at 3 Tesla. METHODS To this end images of 8 human specimens (5 tibiae and 3 radii) and 11 participants (6 tibia and 5 radii) were acquired with both modalities. Additionally, the radius specimens were scanned with micro-CT (muCT), which was used as a standard of reference. Structural parameters calculated from MRI were compared with results from HR-pQCT images and additionally muCT for the radii specimens. RESULTS High correlations (r > 0.7) were found for trabecular number and trabecular spacing between the two modalities in vivo and ex vivo. 2D and 3D analysis revealed high correlations (r > 0.8) in structural bone parameters for all measurements. Using micro-CT as standard of reference both results from QCT and MRI correlated well. CONCLUSION Both imaging modalities were found to perform equally well regarding trabecular bone measurements.
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Affiliation(s)
- R Krug
- Department of Radiology, University of California, San Francisco, CA, USA.
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Abstract
High-resolution finite element models of trabecular bone failure could be used to augment current techniques for measuring damage in trabecular bone. However, the sensitivity of such models to the assumed tissue yield properties and apparent loading conditions is unknown. The goal of this study was to assess the sensitivity of the amount and mode (tension vs. compression) of tissue level yielding in trabecular bone to these factors. Linear elastic, high-resolution finite element models of nine bovine tibial trabecular bone specimens were used to calculate the fraction of the total tissue volume that exceeded each criterion for apparent level loading to the reported elastic limit in both on-axis and transverse compression and tension, and in shear. Four candidate yield criteria were studied, based on values suggested in the literature. Both the amount and the failure mode of yielded tissue were sensitive to the magnitudes of the tissue yield strains, the degree of tension-compression asymmetry of the yield criterion, and the applied apparent loads. The amount of yielded tissue was most sensitive to the orientation of the applied apparent loading, with the most tissue yielding for loading along the principal trabecular orientation and the least for loading perpendicular to it, regardless of the assumed tissue level yield criterion. Small changes in the magnitudes and the degree of asymmetry of the tissue yield criterion resulted in much larger changes in the amount of yielded tissue in the model. The results indicate that damage predictions based on high-resolution finite element models are highly sensitive to the assumed tissue yield properties. As such, good estimates of these values are needed before high-resolution finite element models can be applied to the study of trabecular bone damage. Regardless of the assumed tissue yield properties, the amount and type of damage that occurs in trabecular bone depends on the relative orientations of the applied apparent loads to the trabecular architecture, and this parameter should be controlled for both experimental and computational damage studies.
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Affiliation(s)
- G L Niebur
- Orthopaedic Biomechanics Laboratory, Department of Mechanical Engineering, University of California, CA, Berkeley, USA.
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