Visual identification of vertebral fractures in osteoporosis using morphometric X-ray absorptiometry

Identification of prevalent vertebral fractures using Vertebral Fracture Assessment (VFA) in asymptomatic postmenopausal women: A systematic review and meta-analysis

BACKGROUND

Vertebral fracture (VF) is the most common osteoporotic fracture in postmenopausal women, although most VFs are subclinical. Prevalent VFs are a significant predictor of subsequent fracture and therefore, identification of VF improves the identification of those with high fracture risk. The aim of present study was to systematically review the literature that assessed the prevalence of VF in asymptomatic postmenopausal women, using Vertebral Fracture Assessment (VFA) by dual-energy X-ray absorptiometry.

METHOD

Medline, Web of Science and Cochrane databases were searched between Jan 1st, 2000 and Jan 31st, 2018, for publications in English that reported the prevalence of VFA-detected VF in asymptomatic postmenopausal women. We also searched for reports, conference papers and grey literature. Reviewers screened studies for eligibility and extracted data for included studies. Random effects meta-analyses were performed to calculate the prevalence of VF. The presence of publication bias was assessed using funnel plots by precision and Egger's Test of the Intercept.

RESULTS

A total of 1777 articles were identified, 94 studies were fully reviewed and 28 studies (n = 25,418) met the inclusion criteria and were analyzed. More than two thirds of the studies were cross-sectional and the sample size varied widely across the studies (from 63 to 5156). The mean age ranged from 59.5 to 86.2 years old. The prevalence of osteoporosis and osteopenia varied between 6-57.0% and 25.1-58.9%, respectively. However, among women who had prevalent VFs, up to 43% had osteopenia and as many as 32% had normal bone density. The weighted pooled prevalence of VFA-detected VF in asymptomatic women was 28% (95% CI: 23%-32%).

CONCLUSION

VFA is able to identify prevalent VF in asymptomatic postmenopausal women. The use of VFA identified an average of 28% of asymptomatic women with VFs, many of whom did not have a diagnosis of osteoporosis. Implementation of VFA as a routine screening tool may detect high risk women. Detection of VF might lead to pharmacological treatment in individuals who may not otherwise be treated.

Diagnosis of osteoporotic vertebral fractures in children

Osteoporosis is a generalised disorder of the skeleton with reduced bone density and abnormal bone architecture. It increases bone fragility and renders the individual susceptible to fractures. Fractures of the vertebrae are common osteoporotic fractures. Vertebral fractures may result in scoliosis or kyphosis and, because they may be clinically silent, it is imperative that vertebral fractures are diagnosed in children accurately and at an early stage, so the necessary medical care can be implemented. Traditionally, diagnosis of osteoporotic vertebral fractures has been from lateral spine radiographs; however, a small number of studies have shown that dual energy x-ray absorptiometry is comparable to radiographs for identifying vertebral fractures in children, while allowing reduced radiation exposure. The diagnosis of vertebral fractures from dual energy x-ray absorptiometry is termed vertebral fracture assessment. Existing scoring systems for vertebral fracture assessment in adults have been assessed for use in children, but there is no standardisation and observer reliability is variable. This literature review suggests the need for a semiautomated tool that (compared to the subjective and semiquantitative methods available) will allow more reliable and precise detection of vertebral fractures in children.

ACR Appropriateness Criteria® Osteoporosis and Bone Mineral Density

Osteoporosis is a considerable public health risk, with 50% of women and 20% of men >50 years of age experiencing fracture, with mortality rates of 20% within the first year. Dual x-ray absorptiometry (DXA) is the primary diagnostic modality by which to screen women >65 years of age and men >70 years of age for osteoporosis. In postmenopausal women <65 years of age with additional risk factors for fracture, DXA is recommended. Some patients with bone mineral density above the threshold for treatment may qualify for treatment on the basis of vertebral body fractures detected through a vertebral fracture assessment scan, a lateral spine equivalent generated from a commercial DXA machine. Quantitative CT is useful in patients with advanced degenerative bony changes in their spines. New technologies such as trabecular bone score represent an emerging role for qualitative assessment of bone in clinical practice. It is critical that both radiologists and referring providers consider osteoporosis in their patients, thereby reducing substantial morbidity, mortality, and cost to the health care system. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Are bilateral decubitus views necessary in assessing for vertebral compression fractures using DXA vertebral fracture assessment?

The purpose of this study is to assess the differences in VFA diagnostic accuracy when using bilateral decubitus views and whether diagnostic accuracy is affected by scoliosis. Our findings show that the current practice of performing only one side is valid; however, bilateral views can improve specificity in scoliosis.

INTRODUCTION

The diagnostic accuracy of vertebral fracture assessment (VFA) can be influenced by poor patient position and scoliosis. This study aims to assess the differences in VFA diagnostic accuracy for right and left lateral decubitus views and the effect of scoliosis.

METHODS

One hundred fourteen postmenopausal women received right and left lateral thoracolumbar spine dual-energy VFA and radiography. Cobb angles were measured from the posteroanterior absorptiometry image, and lumbar spine radiography was the standard reference for vertebral fracture and also provides the levels investigated. McNemar's test was used to compare accuracy between the two decubitus position and Fisher's exact test was used for patients with and without scoliosis.

RESULTS

Forty-two vertebral fractures (VFs) were identified. There was no significant difference in sensitivity (p = 0.125) or specificity (p = 0.866) between the left lateral decubitus (64.3, 97.2%) and right lateral decubitus (76.2, 91.1%), respectively, views. Scoliotic patients had a significantly worse specificity (92.7 vs 98.1%, p = 0.003) than patients without scoliosis; however, a combination of both decubitus positions significantly improved specificity (p < 0.001).

CONCLUSION

Right and left side lateral decubitus views have excellent agreement with radiography and similar diagnostic accuracy in the detection of VFs. Thus, the current practice of performing only one side is valid. With scoliosis, bilateral decubitus views can improve the specificity of detecting VF; however, this would increase radiation dose.

Diagnostic accuracy of DXA compared to conventional spine radiographs for the detection of vertebral fractures in children

OBJECTIVES

In children, radiography is performed to diagnose vertebral fractures and dual energy x-ray absorptiometry (DXA) to assess bone density. In adults, DXA assesses both. We aimed to establish whether DXA can replace spine radiographs in assessment of paediatric vertebral fractures.

METHODS

Prospectively, lateral spine radiographs and lateral spine DXA of 250 children performed on the same day were independently scored by three radiologists using the simplified algorithm-based qualitative technique and blinded to results of the other modality. Consensus radiograph read and second read of 100 random images were performed. Diagnostic accuracy, inter/intraobserver and intermodality agreements, patient/carer experience and radiation dose were assessed.

RESULTS

Average sensitivity and specificity (95 % confidence interval) in diagnosing one or more vertebral fractures requiring treatment was 70 % (58-82 %) and 97 % (94-100 %) respectively for DXA and 74 % (55-93 %) and 96 % (95-98 %) for radiographs. Fleiss' kappa for interobserver and average kappa for intraobserver reliability were 0.371 and 0.631 respectively for DXA and 0.418 and 0.621 for radiographs. Average effective dose was 41.9 μSv for DXA and 232.7 μSv for radiographs. Image quality was similar.

CONCLUSION

Given comparable image quality and non-inferior diagnostic accuracy, lateral spine DXA should replace conventional radiographs for assessment of vertebral fractures in children.

KEY POINTS

• Vertebral fracture diagnostic accuracy of lateral spine DXA is non-inferior to radiographs. • The rate of unreadable vertebrae for DXA is lower than for radiographs. • Effective dose of DXA is significantly lower than radiographs. • Children prefer DXA to radiographs. • Given the above, DXA should replace radiographs for paediatric vertebral fracture assessment.

A systematic review of diagnostic accuracy of vertebral fracture assessment (VFA) in postmenopausal women and elderly men

This systematic review was performed to compare the diagnostic accuracy of vertebral fracture assessment (VFA) with that of spinal radiography for identification of vertebral fractures (VFs). VFA appeared to have moderate sensitivity and high specificity for detecting VFs when compared with spinal radiography.

INTRODUCTION

VFs are recognized as the hallmark of osteoporosis, and a previous VF increases the risk of a future fracture. Therefore, the timely detection of VFs is important for prevention of further fractures. This systematic review examined the diagnostic accuracy of VFA using dual X-ray absorptiometry (DXA) to identify VFs.

METHODS

We searched for potentially relevant studies using electronic databases, including Ovid-Medline, Ovid-EMBASE, Cochrane library, and four Korean databases, from their inception to May 2013. We compared the diagnostic accuracy of VFA with that of spinal radiography for detection of VFs by analyzing the sensitivity and specificity using a 2 × 2 contingency table. Subgroup analyses were also performed on studies with a low risk of bias and applicability.

RESULTS

Twelve studies were analyzed for the diagnostic accuracy of VFA. The sensitivity and specificity were 0.70-0.93 and 0.95-1.00, respectively, analyzed on a per-vertebra basis, and 0.65-1.00 and 0.74-1.00 on a per-patient basis. The sensitivity and specificity of five studies in subgroups with a low risk of bias in the intervention test were 0.70-0.84 and 0.96-0.99, respectively. In studies with a low risk of bias in the patient selection, those based on a per-vertebra basis in three studies were 0.70-0.93 and 0.96-1.00, respectively.

CONCLUSIONS

VFA had moderate sensitivity and high specificity for detecting VF when compared with spinal radiography. However, the present findings are insufficient to assess whether spinal radiography should be replaced by VFA.

Dual-Energy X-Ray Absorptiometry: Beyond Bone Mineral Density Determination

Significant improvements in dual-energy X-ray absorptiometry (DXA) concerning quality, image resolution and image acquisition time have allowed the development of various functions. DXA can evaluate bone quality by indirect analysis of micro- and macro-architecture of the bone, which and improve the prediction of fracture risk. DXA can also detect existing fractures, such as vertebral fractures or atypical femur fractures, without additional radiologic imaging and radiation exposure. Moreover, it can assess the metabolic status by the measurement of body composition parameters like muscle mass and visceral fat. Although more studies are required to validate and clinically use these parameters, it is clear that DXA is not just for bone mineral densitometry.

A critical appraisal of vertebral fracture assessment in paediatrics

PURPOSE

There is a need to improve our understanding of the clinical utility of vertebral fracture assessment (VFA) in paediatrics and this requires a thorough evaluation of its readability, reproducibility, and accuracy for identifying VF.

METHODS

VFA was performed independently by two observers, in 165 children and adolescents with a median age of 13.4 years (range, 3.6, 18). In 20 of these subjects, VFA was compared to lateral vertebral morphometry assessment on lateral spine X-ray (LVM).

RESULTS

1528 (84%) of the vertebrae were adequately visualised by both observers for VFA. Interobserver agreement in vertebral readability was 94% (kappa, 0.73 [95% CI, 0.68, 0.73]). 93% of the non-readable vertebrae were located between T6 and T9. Interobserver agreement per-vertebra for the presence of VF was 99% (kappa, 0.85 [95% CI, 0.79, 0.91]). Interobserver agreement per-subject was 91% (kappa, 0.78 [95% CI, 0.66, 0.87]). Per-vertebra agreement between LVM and VFA was 95% (kappa 0.79 [95% CI, 0.62, 0.92]) and per-subject agreement was 95% (kappa, 0.88 [95% CI, 0.58, 1.0]). Accepting LVM as the gold standard, VFA had a positive predictive value (PPV) of 90% and a negative predictive value (NPV) of 95% in per-vertebra analysis and a PPV of 100% and NPV of 93% in per-subject analysis.

CONCLUSION

VFA reaches an excellent level of agreement between observers and a high level of accuracy in identifying VF in a paediatric population. The readability of vertebrae at the mid thoracic region is suboptimal and interpretation at this level should be exercised with caution.

Diagnosis of vertebral fractures using a low-dose biplanar imaging system

Vertebral fractures (VFs) are independent risk factors for new fractures. However, spine radiographs cannot be used as a screening method. EOS® has a good diagnostic value for the diagnosis of VF with a better legibility of upper thoracic spine and a higher concordance between readers compared to vertebral fracture assessment (VFA).

INTRODUCTION

Vertebral fractures (VFs) are risk factors for new fractures. However, spine radiographs cannot be used as a screening method for both cost and radiation concerns. EOS® X-ray imaging system which allows the acquisition of biplane images in an upright weight-bearing position with low radiation dose was used. The objective of this study was to compare EOS® to VFA for the diagnosis of VF.

METHODS

We conducted a cross-sectional study in subjects aged above 50 years with indication for spine imaging. EOS® and VFA of the spine were performed the same day. Sensitivity (Se), specificity (Sp), negative predictive value (NPV), and the interobserver precision of EOS® were compared to VFA for the diagnosis of VF.

RESULTS

Two hundred patients (mean age 66.2 years) were included. At the vertebral level, 2.4 and 3.6 % of vertebrae were not legible using EOS® and VFA, respectively (p = 0.0007). The legibility of spine was significantly affected by scoliosis (odds ratio (OR) = 2.8, p < 0.0001, for EOS®, and OR = 1.8, p = 0.0041, for VFA). Sixty-six patients (33.0 %) and 69 (34.5 %) had at least one VF using VFA and EOS®, respectively. At patient level, Se, Sp, and NPV for the diagnosis of VF of EOS® were 79.7, 91.6, and 99 %, respectively. Concordance between both observers was very good for EOS® (kappa-score = 0.89), higher than for VFA (κ = 0.67).

CONCLUSIONS

This study shows that EOS® has a good diagnostic value for the diagnosis of VF with a better legibility of upper thoracic spine and a higher concordance between readers compared to VFA.

Imaging of vertebral fractures

Vertebral fracture is a common clinical problem. Osteoporosis is the leading cause of non-traumatic vertebral fracture. Often, vertebral fractures are not clinically suspected due to nonspecific presentation and are overlooked during routine interpretation of radiologic investigations. Moreover, once detected, many a times the radiologist fails to convey to the clinician in a meaningful way. Hence, vertebral fractures are a constant cause of morbidity and mortality. Presence of vertebral fracture increases the chance of fracture in another vertebra and also increases the risk of subsequent hip fracture. Early detection can lead to immediate therapeutic intervention improving further the quality of life. So, in this review, we wish to present a comprehensive overview of vertebral fracture imaging along with an algorithm of evaluation of vertebral fractures.

A review of the use of dual-energy X-ray absorptiometry (DXA) in rheumatology

The principal use of dual-energy X-ray absorptiometry (DXA) is to diagnose and monitor osteoporosis and therefore reduce fracture risk, associated morbidity, and mortality. In the field of rheumatology, DXA is an essential component of patient care because of both rheumatologists’ prescription of glucocorticoid treatment as well as the effects of rheumatological diseases on bone health. This review will summarize the use of DXA in the field of rheumatology, including the concern for glucocorticoid-induced osteoporosis, as well as the association of osteoporosis with a sampling of such rheumatologic conditions as rheumatoid arthritis (RA), systemic lupus erythematosus, ankylosing spondylitis, juvenile idiopathic arthritis, and scleroderma or systemic sclerosis. Medicare guidelines recognize the need to perform DXA studies in patients treated with glucocorticoids, and the World Health Organization FRAX tool uses data from DXA as well as the independent risk factors of RA and glucocorticoid use to predict fracture risk. However, patient access to DXA measurement in the US is in jeopardy as a result of reimbursement restrictions. DXA technology can simultaneously be used to discover vertebral fractures with vertebral fracture assessment and provide patients with a rapid, convenient, and low-radiation opportunity to clarify future fracture and comorbidity risks. An emerging use of DXA technology is the analysis of body composition of RA patients and thus the recognition of “rheumatoid cachexia,” in which patients are noted to have a worse prognosis even when the RA appears well controlled. Therefore, the use of DXA in rheumatology is an important tool for detecting osteoporosis, reducing fracture risk and unfavorable outcomes in rheumatological conditions. The widespread use of glucocorticoids and the underlying inflammatory conditions create a need for assessment with DXA. There are complications of conditions found in rheumatology that could be prevented with more widespread patient access to DXA.

Diagnostic performance of vertebral fracture assessment by the lunar iDXA scanner compared to conventional radiography

The purpose of this study was to evaluate the diagnostic performance of vertebral fracture assessment (VFA) using the Lunar iDXA scanner. Conventional spinal radiographs and images acquired by dual-energy X-ray absorptiometry (DXA) of 350 subjects (269 females, 81 males) were evaluated by two different readers. We visualized 4,476/4,550 (98.4 %) vertebrae from T4 to L4 on VFA images compared to 4,535/4,550 (99.7 %) on radiographs. Among the visualized vertebrae, 205/4,535 (4.5 %) and 190/4,476 (4.2 %) were identified as nonfracture deformities by reading of radiographs and VFA, respectively. Vertebral fractures (VFs) were 231 in 126 patients and 228 in 125 patients by semiquantitative assessment of radiographs (SQ-Rx) and by VFA, respectively. There was excellent agreement between the two techniques and high diagnostic performance of VFA both on a per-vertebra basis (k score = 0.984, 95 % CI 0.972-0.996, sensitivity 98.68 %, specificity 99.91 %, PPV 98.25 %, NPV 99.93 %) and on a per-patient basis (k score = 0.957, 95 % CI 0.925-0.988, sensitivity 96.83 %, specificity 98.66 %, PPV 97.60 %, NPV 98.22 %). In older patients (≥65 years) affected by moderate or severe osteoarthritis, SQ-Rx and VFA identified 96 VFs and 95 versus 90 vertebral deformities, respectively. This study demonstrates that most vertebrae are evaluable using the iDXA scanner, with improved VFA diagnostic performance even in discriminating mild VFs from vertebral deformities. Therefore, VFA may be appropriate as an alternative to conventional radiography in patients at high risk of VF who are undergoing DXA bone densitometry and in the follow-up of osteoporotic patients on treatment.

Vertebral morphometry by dual-energy X-ray absorptiometry (DXA) for osteoporotic vertebral fractures assessment (VFA)

PURPOSE

This study was done to evaluate the diagnostic accuracy of dual-energy X-ray absorptiometry (DXA) compared with conventional radiography for identifying vertebral fractures.

MATERIALS AND METHODS

A total of 930 postmenopausal women underwent conventional radiography and DXA imaging of the spine. The images were evaluated by two expert skeletal radiologists using the semiquantitative (SQ) method for conventional radiography and the morphometric vertebral fracture assessment (VFA) for DXA.

RESULTS

The SQ method for radiography (SQ-Rx) analysed 99.1% of vertebrae, identifying 442 vertebral fractures; VFA analysed 97.5% vertebrae, detecting 420 vertebral fractures. Agreement between SQ-Rx and VFA reached 98.76%, and the κ-score was 0.96 [95% confidence interval (CI), 0.95-0.98]. Assessing the grading of vertebral fractures, agreement reached 97.5% and the κ-score was 0.841 (95% CI, 0.821-0.891). Considering SQ-Rx method as "gold standard", VFA had a sensitivity of 97.85 % and a specificity of 99.81%. The negative (NPV) and positive (PPV) predictive value for VFA were 99.83 % and 98.15%, respectively. Fractures were identified in 251 (27 %) and 242 (26 %) of patients on SQ-Rx and VFA, respectively. On a per-patient basis, the agreement between the two methods was 97% and the κ-score was 0.95 (95% CI, 0.920-0.968). The diagnostic parameters for VFA were 97.23% sensitivity, 98.86% specificity, 97.60% PPV and 98.84% NPV.

CONCLUSIONS

This study demonstrated that VFA with DXA may reach a high level of accuracy for diagnosing vertebral fractures, suggesting that VFA should be introduced in the screening of individuals with a risk of osteoporosis and in the follow-up of osteoporotic patients receiving treatment.

Vertebral morphometry by X-ray absorptiometry: which reference data for vertebral heights?

INTRODUCTION

The recent improvement in the resolution of dual-energy X-ray absorptiometry (DXA) images enables most vertebral levels to be seen adequately and thus DXA may be a worthwhile alternative to radiologic morphometry for the identification of vertebral fractures (VF). In this multicenter study, we have derived reference data for vertebral heights and their ratios in Italian women using morphometric X-ray absorptiometry (MXA).

METHODS

DXA scans were acquired in 1254 consecutive pre- and postmenopausal women, (mean age 63.7 ± 11.3, range 26-88 yrs), referred to six osteoporosis centers. MXA analysis of these images was performed by the same operator measuring vertebral heights and height ratios from L4 to T4. We calculated measures of central tendency and dispersion of vertebral heights and vertebral ratios using different approaches (mean and standard deviation as well as median and interquartile range of raw data, mean and standard deviation of trimmed data using an iterative algorithm, and mean and standard deviation of not fractured vertebrae).

RESULTS

Independently of the approach that we used, all the measures of central tendency were similar, while significant differences were found when compared with reference ranges in other populations. The vertebral heights of our sample at every vertebral level were significantly smaller than both Rea population and the Lunar reference values, even after normalization. Splitting data according to age groups, there was a decrease in the vertebral heights and ratios between the younger and older women.

CONCLUSIONS

This study demonstrates that reference data for MXA should be population specific and age matched.

The Prevalence of Undetected Vertebral Fracture in Patients with Back Pain by Dual-Energy X-ray Absorptiometry (DXA) of the Lateral Thoracic and Lumbar Spine

STUDY DESIGN

This is a prospective study.

PURPOSE

This study is conducted to determine the prevalence of unrecognized vertebral fracture (VF) in patients who present with back pain.

OVERVIEW OF LITERATURE

VF is often unrecognized, and significantly increases the risk of further fractures. Unfortunately, the patients at a high risk for VF usually do not receive adequate therapy to reduce the fracture risk.

METHODS

This is a prospective study of 344 patients who presented with back pain from April 2008 to May 2009. The patients underwent dual-energy X-ray absorptiometry (DXA) evaluation and vertebral fracture assessment from T4 to L4 using a hologic densitometer.

RESULTS

Three hundred forty four of 386 patients who presented with back pain were included. Forty two patients were excluded because of a prior history of VF or the lack of written consent. Most of the patients were female (95.3%). The mean age of the patients was 58.21 ± 11.74 years. According to the World Health Organization definition (based on the T-score), 13.4% of the patients had normal lumbar spine bone mineral density (BMD). 27.9% of them were osteopenic and 58.7% were osteoporotic. The overall prevalence of VF, as established by lateral vertebral assessment, was 39% (n = 134). Moreover, 62.6% (n = 84) of the patients with VF had more than one fracture and 64.1% (n = 86) of them had Grade 2 or 3 fracture.

CONCLUSIONS

We recommend performing not only DXA scanning for BMD evaluation, but also VFA by DXA in old patients with back pain.

Detection of vertebral fractures in DXA VFA images using statistical models of appearance and a semi-automatic segmentation

SUMMARY

Morphometric methods of vertebral fracture diagnosis lack specificity. We used detailed shape and image texture model parameters to improve the specificity of quantitative fracture identification. Two radiologists visually classified all vertebrae for system training and evaluation. The vertebral endplates were located by a semi-automatic segmentation method to obtain classifier inputs.

INTRODUCTION

Vertebral fractures are common osteoporotic fractures, but current quantitative detection methods (morphometry) lack specificity. We used detailed shape and texture information to develop more specific quantitative classifiers of vertebral fracture to improve the objectivity of vertebral fracture diagnosis. These classifiers require a detailed segmentation of the vertebral endplate, and so we investigated the use of semi-automated segmentation methods as part of the diagnosis.

METHODS

The vertebrae in a training set of 360 dual energy X-ray absorptiometry images were manually segmented. The shape and image texture of vertebrae were statistically modelled using Appearance Models. The vertebrae were given a gold standard classification by two radiologists. Linear discriminant classifiers to detect fractures were trained on the vertebral appearance model parameters. Classifier performance was evaluated by cross-validation for manual and semi-automatic segmentations, the latter derived using Active Appearance Models (AAM). Results were compared with a morphometric algorithm using the signs test.

RESULTS

With manual segmentation, the false positive rates (FPR) at 95% sensitivity were: 5% (appearance) and 18% (morphometry). With semi-automatic segmentations the sensitivities at 5% FPR were: 88% (appearance) and 79% (morphometry).

CONCLUSION

Specificity and sensitivity are improved by using an appearance-based classifier compared to standard height ratio morphometry. An overall sensitivity loss of 7% occurs (at 95% specificity) when using a semi-automatic (AAM) segmentation compared to expert annotation, due to segmentation error. However, the classifier sensitivity is still adequate for a computer-assisted diagnosis system for vertebral fracture, especially if used in a triage approach.

Bone densitometry and vertebral fracture assessment

Measurement of bone mineral density (BMD) is used to diagnose osteoporosis, assess fracture risk, and monitor response to therapy. Of the different methods for measuring BMD, dual-energy X-ray absorptiometry (DXA) is the only technology for classifying BMD according to criteria established by the World Health Organization (WHO) and the only technology that is validated for BMD input with the WHO fracture risk assessment algorithm, FRAX. Vertebral fracture assessment (VFA) by DXA provides an image of the thoracic and lumbar spine for the purpose of detecting vertebral fracture deformities. Identification of a previously unrecognized vertebral fracture may change diagnostic classification, assessment of fracture risk, and treatment decisions. In comparison with standard radiographs of the spine, the correlation for detecting moderate and severe vertebral fractures is good, with a smaller dose of ionizing irradiation, greater patient convenience, and lower cost. Optimal performance of DXA and VFA requires training and adherence to quality standards.

Vertebral morphometry

Visual semiquantitative (SQ) assessment of the radiographs by a trained and experienced observer is the "gold standard" method to detect vertebral fractures. Vertebral morphometry is a quantitative method to identify osteoporotic vertebral fractures based on the measurement of vertebral heights. Vertebral morphometry may be performed on conventional spinal radiographs (MRX: morphometric x-ray radiography) or on images obtained from dual x-ray absorptiometry (DXA) scans (MXA: morphometric x-ray absorptiometry). Vertebral fracture assessment (VFA) indicates the method for identification of the vertebral fractures using lateral spine views acquired by DXA, with low-dose exposition. For epidemiologic studies and clinical drug trials in osteoporosis research but also in clinical practice, the preferred method is radiographic SQ assessment., because an expert eye can better distinguish between true fractures and vertebral anomalies than can quantitative morphometry. However, vertebral morphometry, calculating the deformity of overall thoracic and lumbar spine, may supply useful data about the vertebral fracture risk. VFA performed during routine densitometry allows identification, by visual or morphometric methods, of most osteoporotic vertebral fractures, even those that are asymptomatic.

Evaluation of vertebral fracture assessment by dual X-ray absorptiometry in a multicenter setting

SUMMARY

The utility of vertebral fracture assessment (VFA) by DXA to detect prevalent vertebral fracture in a multicenter setting was investigated by comparison to conventional radiography. While limited by lower image quality, overall performance of VFA was good but had a tendency to miss mild prevalent fractures.

INTRODUCTION

In osteoporosis clinical trials standardized spine radiographs are used to detect vertebral fractures as a study endpoint. Lateral spine imaging with dual X-ray absorptiometry (DXA) scanners, known as vertebral fracture assessment (VFA) by DXA, presents a potential alternative to conventional radiography with lower radiation dose and greater patient convenience.

METHODS

We investigated in a multicenter setting the ability of VFA to detect fractures in comparison with conventional radiography. The study examined 203 postmenopausal women who had imaging of the spine by DXA and radiography. Three radiologists experienced in vertebral fracture assessment independently read the VFA scans and radiographs using the Genant semiquantitative method on two occasions.

CONCLUSIONS

Analyzing the data from all readable vertebrae, the kappa statistic, sensitivity, and specificity ranged from 0.64-0.77, 0.65-0.84, and 0.97-0.98, respectively. Considering only moderate and severe fractures improved the kappa statistic (0.80-0.91) and sensitivity (0.70-0.86). While image quality of VFA is inferior to radiography, the detection of vertebral fractures using visual scoring is feasible. However, VFA underperformed due to unreadable vertebrae and reduced sensitivity for mild fractures. Nevertheless, VFA correctly identified most moderate and severe vertebral fractures. Despite this limitation, VFA by DXA provides an important tool for clinical research.

Vertebral fracture assessment in supine position: comparison by using conventional semiquantitative radiography and visual radiography

PURPOSE

To retrospectively evaluate the accuracy of vertebral fracture assessment (VFA) performed with the patient in the supine position and conventional semiquantitative radiography of the spine by using conventional visual radiography of the spine as the reference standard.

MATERIALS AND METHODS

This retrospective study was approved by the institutional ethics review board; informed consent was obtained from the patients. A total of 250 consecutive patients (mean age, 62.0 years; range, 25-89 years) consisting of 190 women (mean age, 64 years; range, 25-89 years) and 60 men (mean age, 57.0 years; range, 27-83 years) who were suspected of having osteoporosis and who underwent VFA in the supine position and radiography of the spine were evaluated. VFA and semiquantitative radiography were analyzed by using a six-marker point method to describe the shape and deformity of each vertebra. Visual radiography of the lateral spine was performed by an experienced radiologist. The agreement between VFA, visual radiography, and semiquantitative radiography of semiquantitative graded fractures was assessed by using weighted kappa statistics.

RESULTS

Visual radiography helped identify 92 (36.8%) patients with at least one vertebral fracture (mean, 1.8 per patient). Most fractures were present in T7, T12, and L1. Excellent agreement was found between VFA and visual radiography, with 97.5% concordance and kappa = 0.82; VFA and semiquantitative radiography were in agreement in 97.4% of patients, with kappa = 0.83; and visual radiography and semiquantitative radiography were in agreement in 98.1%, with kappa = 0.87. Sensitivity, specificity, and positive and negative predictive values calculated by lesion level for VFA compared with visual assessment were 83.6%, 99.1%, 84.1%, and 99.1%, respectively.

CONCLUSION

VFA performed with patients in the supine position is an accurate method to help detect vertebral fractures when compared with conventional spine radiography. VFA permits combination of fracture assessment with bone mineral density measurement in a single session.

Vertebral Fracture Assessment: the 2007 ISCD Official Positions

Vertebral fracture assessment (VFA) is an established, low radiation method for detection of prevalent vertebral fractures. Vertebral fractures are usually not recognized clinically at the time of their occurrence, but their presence indicates a substantial risk for subsequent fractures independent of bone mineral density. Significant evidence supporting VFA use for many post-menopausal women and older men has accumulated since the last ISCD Official Position Statement on VFA was published. The International Society for Clinical Densitometry considered the following issues at the 2007 Position Development Conference: (1) What are appropriate indications for Vertebral Fracture Assessment; (2) What is the most appropriate method of vertebral fracture detection with VFA; (3) What is the sensitivity and specificity for detection of vertebral fractures with this method; (4) When should additional spine imaging be performed following a VFA; and (5) What are the reporting obligations for those interpreting VFA images?

Algorithm-based qualitative and semiquantitative identification of prevalent vertebral fracture: agreement between different readers, imaging modalities, and diagnostic approaches

We compared SQ and ABQ diagnosis of VF imaged by radiography and X-ray absorptiometry. Mild ABQ VF had stronger associations with osteoporosis than mild SQ VF. Interobserver agreement (radiographic diagnosis) was better for ABQ.

INTRODUCTION

Vertebral fracture (VF) assessment from images acquired by X-ray absorptiometry (VFA) is often based on a semiquantitative approach (SQ); prevalent VF is identified if vertebral height appears reduced by >20%. Algorithm-based qualitative definition of osteoporotic VF (ABQ) requires evidence of endplate depression, and there is no threshold for reduction in vertebral height. The aims of this study were to (1) compare the prevalence of VFs; (2) compare the characteristics of women with and without VFs; (3) compare interobserver agreement; and (4) compare agreement between methods and imaging modalities for ABQ and SQ definitions of VFs.

MATERIALS AND METHODS

Spine radiographs and absorptiometry images for 203 elderly women were assessed using ABQ (readers ABQ-1 and ABQ-2). These readings were compared with SQ assessments (readers SQ-1 and SQ-2) of the same images performed in a previous study. Agreement between readers and methods was assessed by kappa (kappa) statistics.

RESULTS

The prevalence of VF was 15-18% (radiography) and 12-24% (VFA) for ABQ and SQ, respectively. Women with ABQ or SQ fractures were older and had lower BMD than those without fracture (p < 0.01). Mild ABQ (but not SQ) VF was associated with low BMD. Kappa scores for interobserver agreement for radiography and VFA, respectively, were as follows: ABQ, kappa = 0.74 (95% CI, 0.60, 0.87) and 0.65 (95% CI, 0.48, 0.81); SQ, kappa = 0.53 (95% CI, 0.46, 0.60) and 0.51 (95% CI, 0.44, 0.58). For agreement between ABQ-1 and SQ-1, kappa = 0.55 (95% CI, 0.39, 0.72) for radiography and 0.41 (95% CI, 0.25, 0.58 for VFA.

CONCLUSIONS

The prevalence of radiographic VF identified by ABQ and SQ was similar, but on VFA was 50% higher for SQ. Mild ABQ VF was associated with low BMD. Interobserver agreement for radiographic diagnosis was significantly better for ABQ than for SQ. Agreement between ABQ and SQ was moderate.

Comparison of densitometric and radiographic vertebral fracture assessment using the algorithm-based qualitative (ABQ) method in postmenopausal women at low and high risk of fracture

Using ABQ diagnosis, the sensitivity to detect VF of densitometric versus radiographic assessment in 755 postmenopausal women was 71-81% and specificity was 97%. Misdiagnosis was influenced by image quality and was more common for mild deformities.

INTRODUCTION

Using densitometric vertebral fracture assessment (VFA), prevalent fractures are identified when vertebral height appears reduced by >or=20%. However, this approach does not discriminate between osteoporotic vertebral fracture (VF) and nonosteoporotic deformity, which increases the false-positive rate. Algorithm-based qualitative diagnosis (ABQ) focuses on vertebral endplate fracture to exclude these deformities but has not been applied in VFA. We wished to determine whether densitometric image quality is adequate for ABQ assessment. Our aims were to (1) calculate agreement between VFA and radiography using ABQ to identify prevalent VF and (2) identify the primary reasons for any discordant diagnosis.

METHODS

Radiographic and densitometric spine images for postmenopausal women at low risk (LR; n = 459) and high risk (HR; n = 298) of VF were assessed using ABQ. Agreement between imaging modalities for VF diagnosis was assessed by kappa statistics using ABQ radiographic readings as the gold standard.

RESULTS

The prevalence of VF was 11-29% (radiography) and 9-26% (VFA) in the LR and HR groups, respectively. Agreement between imaging modalities was good or very good (kappa = 0.62-0.81 in the LR and HR populations). The sensitivity to detect women with VF by VFA was 71% and 84% in the LR and HR populations, respectively, and specificity was 97%. Fifty-two (77%) and 60 (61%) of vertebrae misclassified by VFA in the LR and HR populations were mild fractures and 37 (54%) and 62 (63%) were wedge fractures. One third of fractures missed by VFA were related to poor or unreadable image quality (n = 27 and 28 vertebrae in the LR and HR populations, respectively).

CONCLUSIONS

There was good agreement between VFA and radiography using ABQ to identify prevalent VF in women at LR or HR of osteoporotic VF. Vertebrae misclassified by VFA were primarily mild fractures or deformities, and two thirds of all fractures missed by VFA were related to poor or unreadable image quality.

The relationship of an Asian-specific screening tool for osteoporosis to vertebral deformity and osteoporosis

An Asian-specific screening tool for osteoporosis, the so-called OSTA index, was devised and is likely to be helpful in determining which postmenopausal women need bone mineral density (BMD) measurement. Besides BMD, prevalent vertebral fracture is a strong risk factor for future fractures. However, the relationship of the OSTA index to prevalent vertebral fractures is currently unknown. In this study, we evaluated the performance of the OSTA index in elderly Thai women and assessed the relationship of the index to prevalent vertebral deformities. Subjects consisted of 741 healthy Thai elderly women. BMD was measured by DEXA and T-score <or=2.5 SD is defined as osteoporosis. Prevalent vertebral deformities were determined by morphometric X-ray absorptiometry. OSTA index >-1 is classified as having low risk of osteoporosis, -1 to -4 as intermediate risk and, <-4 as high risk. Data were expressed as mean +/- SD. The mean age and body weight of subjects were 67 +/- 4.8 years and 57.8 +/- 8.7 kg, respectively. The area under the ROC curve for OSTA index to identify osteoporosis at femoral neck and lumbar spine was 0.80 and 0.72, respectively. Femoral neck osteoporosis was found in 40.4%, 6.3%, and 2.4% of subjects with high-risk, intermediate-risk, and low-risk OSTA indexes, respectively. With regard to vertebral deformities, the area under the ROC curve relating OSTA index to vertebral deformities was 0.70 (P < 0.001). The prevalence of vertebral deformities in according to the OSTA index was 19.2% in the high-risk, 7.9% in the intermediate-risk, and 2.8% in the low-risk group. We concluded that the OSTA index can be of assistance in the selection of postmenopausal women for BMD measurement. In addition, this index may be helpful in the identification of postmenopausal women with vertebral deformity and those who need antifracture treatments.

Vertebral fracture assessment in patients presenting with incident nonvertebral fractures

BACKGROUND

Patients with fractures should be prioritized for assessment for osteoporosis so that they can benefit from treatment for the secondary prevention of osteoporotic fractures. Assessment is seldom offered to patients with vertebral fractures because these fractures are typically not diagnosed. Vertebral fractures can be identified by vertebral fracture assessment (VFA) using current dual-energy X-ray absorptiometry (DXA) scanners.

OBJECTIVE

The purpose of this study was to assess the prevalence of vertebral fractures, using VFA, in patients presenting with nonvertebral fractures and to assess whether this impacts on the management of these patients.

DESIGN

A cohort study undertaken in 577 patients aged 50 years or over including 455 women, who presented with nonvertebral fractures and who underwent routine post-fracture assessment by a Fracture Liaison Service (FLS).

MEASUREMENTS

The numbers and severity of vertebral fractures were assessed in evaluable vertebrae from TV4 to LV4 in addition to bone mineral density (BMD) assessment.

RESULTS

Using DXA, 76% of vertebrae could be evaluated by VFA. Of the men and women with nonvertebral fractures, 19-20% had at least one vertebral fracture. The prevalence ranged from 6% in men with humeral fractures to 32% among women with hip fractures. The prevalence of vertebral fractures correlated most strongly with increasing age and with severity of reduction of BMD. Using local treatment protocols, VFA would result in only 3% more patients receiving treatment for fracture secondary prevention.

CONCLUSIONS

In patients with nonvertebral fractures, VFA identifies a substantial burden of prevalent vertebral fractures that have not hitherto been recognized. Nevertheless, VFA seldom influences the need for treatment for fracture secondary prevention after a nonvertebral fracture.

Quantitative vertebral fracture detection on DXA images using shape and appearance models

RATIONALE AND OBJECTIVES

Current quantitative morphometric methods of vertebral fracture detection lack specificity, particularly with mild fractures. We use more detailed shape and texture information to develop quantitative classifiers.

MATERIALS AND METHODS

The detailed shape and appearance of vertebrae on 360 lateral dual energy x-ray absorptiometry scans were statistically modeled, thus producing a set of shape and appearance parameters for each vertebra. The vertebrae were given a "gold standard" classification using a consensus reading by two radiologists. Linear discriminants were trained on the vertebral shape and appearance parameters.

RESULTS

The appearance-based classifiers gave significantly better specificity than shape-based methods in all regions of the spine (overall specificity 92% at a sensitivity of 95%), while using the full shape parameters slightly improved specificity in the thoracic spine compared with using three standard height ratios. The main improvement was in the detection of mild fractures. Performance varied over different regions of the spine. False-positive rates at 95% sensitivity for the lumbar, mid-thoracic (T12-T10) and upper thoracic (T9-T7) regions were 2.9%, 14.6%, and 5.5%, respectively, compared with 6.4%, 32.6%, and 21.1% for three-height morphometry.

CONCLUSION

The appearance and shape parameters of statistical models could provide more powerful quantitative classifiers of osteoporotic vertebral fracture, particularly mild fractures. False positive rates can be substantially reduced at high sensitivity by using an appearance-based classifier, because this can better distinguish between mild fractures and some kinds of non-fracture shape deformities.

Vertebral Fracture Assessment by dual-energy X-ray absorptiometry: insurance coverage issues in the United States. A White Paper of the International Society for Clinical Densitometry

Clinical trial data and fracture risk prediction models unequivocally demonstrate the utility of identifying prevalent vertebral fractures to predict future fractures of all types. Knowledge of prevalent vertebral fractures can alter patient management decisions and result in initiation of therapy to reduce fracture risk in some patients who would not otherwise be treated. Cost-benefit analysis demonstrates that identifying and treating patients with vertebral fractures, even those with a densitometric classification of osteopenia, is cost effective. Vertebral fractures can be readily identified in the office setting using standard radiography or Vertebral Fracture Assessment (VFA), a software addition to a central dual-energy X-ray absorptiometry (DXA) machine. In the United States, VFA was assigned a Current Procedural Terminology (CPT) code in January 2005. Nevertheless, coverage of VFA has not been uniformly embraced by Medicare carriers, companies that contract with the federal government to administer Medicare coverage and process claims for a region of the United States. Unlike DXA, for which uniform national coverage of qualified Medicare beneficiaries is mandated by the Balanced Budget Act of 1997, VFA coverage policies are determined by the local Medicare carriers. Third-party insurers are also variable in their coverage of VFA. This International Society for Clinical Densitometry (ISCD) White Paper documents the role of VFA in the evaluation and treatment of women with postmenopausal osteoporosis and compares it with standard spine radiography. Arguments used by some Medicare carriers and insurers to deny coverage of VFA in the United States are analyzed and critiqued. For health care providers within the United States, this White Paper may serve as a resource to respond to insurers who deny coverage of VFA. For health care providers regardless of their country, this article underscores the value of VFA as an alternative to spine radiography in the evaluation and management of postmenopausal women with suspected osteoporosis.

Influence of age and sex on lumbar vertebral morphometry determined using sagittal magnetic resonance imaging

We evaluated age-related changes in the morphometric features of lumbar vertebrae in both sexes using magnetic resonance imaging (MRI). Midsagittal MRI scans of 366 individuals (156 males, 210 females; 25-82 years old) were evaluated retrospectively. The anterior height (H(a)), central height (H(c)), posterior height (H(p)), and anteroposterior diameter (D) of the body of each lumbar vertebra were measured. These measurements were used to calculate three indices, namely, the anterior wedge index (H(a)/H(p)), the biconcavity index (H(c)/H(p)), and the compression index (H(p)/D). The values of each of the three indices for the upper lumbar vertebrae of females were higher than those of the same vertebrae in males. The values of the compression index for all lumbar vertebrae decreased with age in females, whereas in males the compression index of the L1-L4 vertebrae decreased with age. No significant changes were observed in the value of the anterior wedge index in either sex. The biconcavity indices of the L1 and L5 vertebrae decreased with age in males. These results may be useful for evaluating age-related morphological changes that occur in the lumbar vertebrae.

Outcomes of a nurse-led osteoporosis and falls assessment

Osteoporosis is a major public health concern. Recent evidence from clinical and epidemiological trials on osteoporosis has stressed the urgency for early and accurate diagnosis of vertebral fractures. Despite the fact that vertebral fractures are very common and associated with decreased quality of life, they are frequently missed in daily clinical practice. The authors developed a protocol to be applied through a specialized nurse-led osteoporosis vertebral fracture service that allows for accurate diagnosis, identifies patients at risk and shortens the time of assessment and management. A total of 114 patients have been reviewed over 12 months. Completing the referral form and the clinic proforma helped the nurse cover all causes of vertebral fractures and shortened the lag time for assessment and management. Osteoporosis therapy was commenced once diagnosis was confirmed.

Risk factors for prevalent vertebral fractures in black and white female densitometry patients

This cross-sectional study compared risk factors for prevalent vertebral fractures (diagnosed using densitometric spine image Vertebral Fracture Assessment [VFA]) in 176 black and 345 white women recruited during their clinical bone mineral density (BMD) testing at the University of Chicago Hospitals. We used logistic regression to assess the association of prevalent vertebral fractures and risk factors (age, height loss, history of nonvertebral fractures, BMD, and use of corticosteroids). The prevalence of vertebral fractures was 21% for both races. All risk factors of interest were significantly associated with vertebral fractures in white women. Among black women, only age and corticosteroid use were found to be significant predictors of presence of vertebral fracture(s). In women without history of corticosteroid use, the probability of having vertebral fracture(s) given age was lower (p=0.02) in black subjects. In 77 patients with a history of corticosteroid use, the probability of having vertebral fracture(s) was higher in black than in white women after adjustment for age (p=0.045), BMD (p=0.045), or cumulative corticosteroid dose (p=0.08). Fewer black women were prescribed pharmacologic therapy for osteoporosis, regardless of their BMD level and corticosteroid use. We conclude that use of corticosteroids may be associated with relatively greater vertebral fracture risk in blacks than in whites.

Vertebral Morphometry

OBJECTIVES

Manual point placement for vertebral morphometry is time-consuming and imprecise. We evaluated the accuracy of semiautomatic computer determination of the detailed vertebral shape.

MATERIALS AND METHODS

The shape and appearance of vertebrae on 250 lateral dual-energy x-ray absorptiometry (DXA) scans were statistically modeled using a sequence of active appearance models of vertebral triplets. The models were matched to unseen scans given an approximate initial location of the center of each vertebra. The segmentation accuracy was analyzed by fracture grade.

RESULTS

Segmentation accuracy comparable to manual precision was obtained in the case of normal vertebrae, but the accuracy decreased with increasing fracture severity. We propose methods for improving the robustness for severe fractures.

CONCLUSION

Vertebral morphometry measurements may be substantially automated even on noisy data with multiple fractures present. The shape and appearance parameters of the models could provide more powerful quantitative classifiers of osteoporotic vertebral fracture.

Clinical review: Clinical applications of vertebral fracture assessment by dual-energy x-ray absorptiometry

CONTEXT

Vertebral fracture (VF) is the most common type of fragility fracture, yet most VFs are not clinically apparent. VFs are associated with a significant increase in morbidity, mortality, and risk of future fracture. Many patients with VFs do not have T-scores classified as osteoporosis. Knowledge of VFs may change diagnostic classification, estimation of future fracture risk, and clinical management. VF assessment (VFA) by dual-energy x-ray absorptiometry is a method for imaging the spine to diagnose VFs.

EVIDENCE ACQUISITION

Background information and medical evidence on the technology and clinical applications of VFA was acquired by electronic searching of PubMed for appropriate terms that included vertebral fracture, imaging, diagnosis, dual-energy x-ray absorptiometry, and cost effectiveness. Matches with the highest levels of medical evidence were selected for review, recognizing that the new and evolving nature of the field required inclusion of some material that relied partly on expert opinion.

EVIDENCE SYNTHESIS

The sensitivity and specificity of VFA compare favorably with spine radiographs in the ability to diagnose grade 2 and 3 VFs. VFA involves less radiation, lower cost, and often greater patient convenience than spine radiography. Cost effectiveness modeling suggests that imaging of the spine in selected patients provides essential diagnostic and therapeutic information at a nominal cost. Patients with T-scores that are classified as low bone mass (osteopenia) who are selected for pharmacological therapy based on the presence of a VF benefit by reduction in fracture risk. Guidelines for the clinical application of VFA have been developed by the International Society for Clinical Densitometry.

CONCLUSIONS

VFA is a technology for diagnosing VFs that may alter diagnostic classification, improve fracture risk stratification, and identify patients likely to benefit from pharmacological therapy who otherwise might not be treated.

[Fracture diagnosis in osteoporosis]

As life expectancy rises the prevalence of osteoporosis also increases, which represents a growing burden for the populace and the healthcare system. Vertebral fractures are the most frequent type of all osteoporotic fractures. Since they can be diagnosed by radiology, these examinations are particularly important for devising suitable treatment strategies. The goal of activities undertaken by osteoporosis organizations is to put across to radiologists the importance of accurate evaluation of these fractures. Identification of osteoporotic vertebral fractures is however problematic since the transition from healthy vertebral bodies to those deformed by osteoporosis constitutes a continuum and it is often difficult in deformed vertebral bodies to distinguish between an osteoporotic fracture and a non-osteoporotic deformity. This overview attempts to heighten awareness of the significant role the radiologist plays in the diagnostic work-up of osteoporosis and to provide diagnostic aids for assessing osteoporotic vertebral fractures including differential diagnoses.

Influence of baseline deformity definition on subsequent vertebral fracture risk in postmenopausal women

INTRODUCTION

Approaches for recognizing vertebral fractures remain controversial.

METHODS

An age-stratified population sample of 512 postmenopausal women was followed with serial radiographs for up to 12 years (4455 person-years).

RESULTS

112 women experienced a new vertebral fracture (20% reduction in any vertebral height from baseline) within this study period, for an annual age-adjusted (to US white women > or =50 years of age in 2000) incidence of 23 per 1000. Depending on the morphometric definition used, the prevalence of vertebral deformities at baseline ranged from 3 to 90%. A recent method to standardize vertebral heights produced the best agreement with a qualitative clinical reading of the films [kappa (kappa), 0.53]. Almost all of the different baseline definitions predicted future vertebral fractures, but most of the predictive power was attributable to the severe (e.g., 4 SD) deformities included within more generous (e.g., 3 SD) classifications. Whereas the generous definitions were more sensitive, and the restrictive ones more specific, their overall abilities to predict a new vertebral fracture were roughly comparable as evaluated by the c-index (analogous to the area under an ROC curve).

CONCLUSION

This result suggests that the choice of a morphometry definition depends on the particular application and, in particular, on whether it is more important to maximize sensitivity or specificity.

Diagnosis of vertebral fractures by vertebral fracture assessment

Vertebral fractures are independent risk factors for both vertebral and peripheral fractures and only one-third of these fractures come to clinical attention. Vertebral fracture assessment (VFA) is a radiographic method using dual X-ray absorptiometry (DXA) to assess vertebral deformities during bone density measurement. We performed VFA of the spine from T4 to L5 on a Delphi W device (Hologic, Bedford, MA) in 136 postmenopausal patients (69+/-10 yr). These patients also had X-rays of the thoracic and lumbar spine. VFA was independently compared with X-rays by two rheumatologists, for the diagnosis of vertebral fractures at both the patient and vertebral levels. Using X-rays, 61 patients (45%) had at least one vertebral fracture. The percentage of unreadable vertebrae was 1% and 12.4% on X-rays and VFA, respectively (p<0.0001). At the patient level, VFA allowed to diagnose if the patient had no fracture or had at least one fracture in 74% of patients. In 11.2% of cases, VFA misclassified the patients. At the vertebral level, diagnostic efficacy of VFA as compared with X-rays was 97%. Concordance between both observers was good (kappa-score=0.69). We designed an algorithm for decision of performing X-rays in postmenopausal women: Using results of VFA would avoid X-rays in 32% of our patients. VFA is a reliable technique with low radiation, and is easily and rapidly applicable during bone density measurement by DXA, which could improve management of osteoporotic patients.

Effectiveness of instant vertebral assessment to detect prevalent vertebral fracture

INTRODUCTION

Vertebral fracture is currently underdiagnosed, despite its common severity and its value to predict further osteoporotic fracture. Morphometry using dual X-ray absorptiometry (DXA) [vertebral fracture assessment (VFA)] is a new technique that may facilitate detection of many vertebral fractures, as images are obtained at the same time as bone mineral density (BMD) measurement, and would also allow avoiding spine radiographs.

METHODS

We conducted a cross-sectional study to assess the diagnostic value of Instant Vertebral Assessment (IVA), which is a morphometry scan using the Hologic Delphi densitometer, to detect prevalent vertebral fracture in postmenopausal women. Interobserver precision was assessed, then IVA scans were compared with lateral spine radiographs, considered the gold standard, to test diagnostic agreement between the two techniques. Sensitivity, specificity and predictive values were calculated, as well as the likelihood ratio of the positive test, using sensitivity and specificity at each vertebral level.

RESULTS

Among 85 patients of whom 50% had at least one vertebral fracture identified with radiographs, we found that interobserver precision was moderate, with frequent difficulties in discerning upper thoracic vertebrae. On a per-vertebra basis, sensitivity was around 70% from L4 to T11 and lower above T11 whereas specificity was above 90% for all vertebrae, and the negative predictive value remained above 80% from L4 to T7 and decreased above T7. On a per-patient basis, sensitivity was 0.69, specificity 0.74, positive predictive value equalled 0.72 and negative predictive value 0.71. When only grades 2 and 3 fractures were considered, results were comparable, with slightly improved specificity. Then, with the likelihood ratios calculated in our sample, we obtained posttest probabilities using the prevalence of vertebral fracture at lumbar and thoracic levels in a large sample of postmenopausal women with osteopenia and osteoporosis with and without vertebral fracture [baseline data in women of the Multiple Outcomes on Raloxifene Evaluation (MORE) trial]. At levels where fractures were most common, likelihood ratios of the positive test were good or excellent, associated with sizeable posttest probabilities.

CONCLUSION

IVA allowed diagnosis of vertebral fracture at levels where vertebral fracture were most common, i.e., the lumbar and mid and lower thoracic levels, but its value was weaker at the upper thoracic levels.

Vertebral fracture assessment: the 2005 ISCD Official Positions

Vertebral Fracture Assessment (VFA) is a low radiation method for imaging the thoraco-lumbar spine using bone densitometers. VFA can easily be performed at the time of bone mineral density (BMD) measurement, allowing integration of BMD and vertebral fracture information into clinical patient care. As VFA is a relatively new procedure, it has received limited study and heretofore has not had widespread clinical application. Consequently, the International Society for Clinical Densitometry (ISCD) considered the following VFA issues at the 2005 Position Development Conference: (1) indications for VFA; (2) methodology for the diagnosis of vertebral fractures using VFA; and (3) indications for additional imaging after VFA. The ISCD Official Positions with respect to the above issues, as well as the rationale and evidence used to derive these positions, are presented here.

Morphometric X-ray absorptiometry in the assessment of vertebral fractures in renal transplant patients

BACKGROUND

Bone mineral density (BMD) is widely employed to evaluate the risk of fractures, but more than mineral content is bone quality that accounts for bone strength. In fact, occasionally, subjects with normal or only mildly reduced BMD also experience pathologic fractures. In metabolic bone disease, like renal transplantation, the agreement between fractures and BMD is less predictable. We assessed the prevalence of vertebral fractures by means of a new, DEXA-based method (morphometric absorptiometry, MXA) and compared its concordance with the two mostly employed radiological techniques (Visual semi-quantitative, SQ, and morphometric radiography, MRX) in an asymptomatic population of transplanted patients. Moreover, the association of bone fractures with low BMD values was examined.

METHODS

Fifty-three renal transplant patients underwent spinal radiographs and BMD measurements by DEXA. In order to obtain a morphometric assessment, a lateral DEXA scan was performed.

RESULTS

Patients with vertebral fracture were 17/53 (32%) with both SQ and MRX, and 12/53 (23%) with MXA (chi(2) = n.s.). A single fracture was detected in 9/53 patients (17%) with SQ and MRX, and in 4/53 (7.5%) with MXA; multiple fractures were 8/53 (15%) with any technique. With SQ as the standard reference, predictive indexes were excellent with MRX (invariably 100%) and quite good with MXA (sensitivity 70.6%; specificity 100%). Of the total of 689 vertebrae, 49 were fractured with SQ, 54 with MRX and 41 with MXA. Mild deformities were present in 21 (SQ), 26 (MRX) and 13 (MXA) vertebral bodies, respectively, while moderate-severe deformities were 28 with any technique. Again, with SQ as standard reference, predictive indexes were good (MRX: sensitivity 100%, specificity 99.2%; MXA: sensitivity 83.7%, specificity 100%). When we classified patients according to BMD T-score values, SQ and MRX recognized fractures in 4/18 normal (22%), 10/22 osteopenic (45%) and 3/13 osteoporotic (23%). With MXA 3/18 (17%) normal, 6/22 (27%) osteopenic and 3/13 (23%) osteoporotic were fractured. The lower performance of MXA was very likely due to the poor quality of images from the upper thoracic spine of obese subjects.

CONCLUSIONS

Prevalence of vertebral fractures in renal transplant patients is quite high and randomly associated with reduced BMD. A surveillance of the spine by Rx, implemented with vertebral morphometry, is therefore warranted to recognize the disease. (MXA is a reliable alternative technique, especially in more severely affected individuals.) MXA, although less sensitive than the conventional techniques because of possible technical biases, is very specific, and can be proposed for follow-up purposes in this population of patients.

Vertebral Deformities Identified by Vertebral Fracture Assessment

Whether vertebral fractures identified on radiographs are painful or not, they are associated with increased morbidity and mortality. Vertebral fractures on X-rays correlate with low bone mineral density (BMD) at the spine and hip in addition to several clinical characteristics. Evidence suggests that vertebral deformities detected by X-ray and by vertebral fracture assessment (VFA) show good agreement. We examined the relationship between VFA-detected vertebral deformities and patient characteristics as well as BMD by analyzing the records of 432 patients who had undergone dual-energy X-ray absorptiometry (DXA) scans with VFA. Patients' demographic data and T-scores were obtained from patient questionnaires and DXA scans. We categorized vertebral deformities by type and severity. Patients with vertebral deformities were significantly older and more likely to report a history of fracture after childhood. Significantly more estrogen use was reported in patients without deformity. Those with deformities had significantly lower T-scores at the femoral neck and total hip but not at the spine. Increased severity and number of deformities correlated with lower T-scores at the total hip and femoral neck but not the spine. In conclusion, vertebral deformities detected by VFA, like those on X-ray, correlate with both clinical characteristics and reduced bone mass at the hip. These relationships, in addition to rapid performance, convenience, and minimal radiation exposure, indicate VFA-detected vertebral deformities are a valuable adjunct in identifying patients in need of additional evaluation and treatment.

Identification of vertebral fractures: an update

Osteoporotic vertebral fracture is associated with increased morbidity and mortality. As a powerful predictor of future fracture risk, the identification of vertebral fracture helps target individuals who will benefit from anti-fracture therapy. The identification of vertebral fractures is problematic because (1) "normal" radiological appearances in the spine vary greatly both among and within individuals; (2) "normal" vertebrae may exhibit misleading radiological appearances due to radiographic projection error; and (3) "abnormal" appearances due to non-fracture deformities and normal variants are common, but can be difficult to differentiate from true vertebral fracture. Various methods of vertebral fracture definition have been proposed, but there is no agreed gold standard. Quantitative methods of vertebral fracture definition are objective and reproducible, but the major limitation of these methods is their inability to differentiate between vertebral deformity and vertebral fracture. The qualitative visual approach draws on the expertise of the reader, but it is a subjective method with poor interobserver agreement. Semiquantitative assessment of vertebral fracture is a standardized visual method, which is commonly applied in research studies as a surrogate gold standard. This method is more objective and reproducible than a purely qualitative approach, but can be difficult to apply. The established methods focus primarily on the identification of "reduced" or short vertebral height as an indication of vertebral fracture, but this is also a feature of some non-fracture deformities and normal variants. A modified visual approach known as algorithm-based qualitative assessment of vertebral fracture (ABQ) has recently been introduced, and this focuses on radiological evidence of change at the vertebral endplate as the primary indicator of fracture. Preliminary testing of the ABQ method has produced promising results, but the method requires further evaluation. Vertebral imaging by means of dual energy X-ray absorptiometry (DXA) scanner produces images of near-radiographic quality at a fraction of the radiation dose incurred by conventional radiography. There is growing interest in vertebral fracture assessment using this technique as a means of assessing a patient's fracture risk. Given the increasing availability of new technology and the importance of accurate diagnosis of vertebral fracture, there is an urgent need for better awareness of and training in the definition of vertebral fracture. Methods of vertebral fracture definition should be validated by testing the association with clinical outcomes of vertebral fracture, in particular the prediction of incident fractures.

Assessment of vertebral fracture using densitometric morphometry

Diagnosis of vertebral fracture is critical for management of osteoporosis, as existence of such deformities substantially increases the risk of subsequent fracture. Thus, accurate and precise techniques allowing detection of such deformities are essential to clinicians. So far, this detection has been performed by spinal lateral X-rays. More advanced techniques have recently been developed, based on dual energy X-ray absorptiometry (DXA). This review describes these different techniques and discusses the effectiveness of the DXA technique to assess vertebral deformities compared to X-ray. The use of DXA detection of vertebral fracture for clinical practice and clinical trials is discussed. Specifically, vertebral morphometry using DXA provides an excellent specificity, with moderate sensitivity. The major limitation of the DXA vertebral assessment is the poor quality of images of thoracic vertebrae. The clinical utility of vertebral morphometry using densitometry may help screening patients with vertebral fracture, but technological improvements are necessary to improve image quality.

Comparison of T-scores from different skeletal sites in differentiating postmenopausal women with and without prevalent vertebral fractures

It is not clear how bone mineral density (BMD) measurements from several regions of lumbar spine and proximal femur should be utilized in assessing fracture risk. We examined how well the newest ISCD recommendations differentiate subjects with and without prevalent vertebral fractures in 187 postmenopausal women presenting for routine bone densitometry. The association between T-scores from proximal femur and lumbar spine sites and the probability of having a vertebral fracture was modeled via logistic regression with adjustment for age. The lowest T-score of any hip or spine sites (the current ISCD recommendation) and the proximal femur measurements, particularly the femoral neck and total hip, displayed the strongest association with the probability of vertebral fractures.Subjects with a T-score < -2.5 at multiple hip sites had a higher probability of having a vertebral fracture. The sensitivity and specificity associated with particular T-score cutoff values varied greatly depending on the site of measurement.Consequently, T-score values from different sites that had comparable sensitivity/specificity for detecting the presence of vertebral fractures differed by as much as 1.5 T-score units. This finding implies that a single cutoff value, such as -2.5, might not be clinically acceptable when applied to T-scores from different sites.

When should the doctor order a spine X-ray? Identifying vertebral fractures for osteoporosis care: results from the European Prospective Osteoporosis Study (EPOS)

Vertebral fractures are common but usually remain unrecognized in primary care. Data from 2908 women and 2653 men in the EPOS study were used to derive algorithms to indicate the need for a spine X-ray to identify a fracture using easily elicited determinants. At a sensitivity of 50% for identifying cases, the specificity was increased from 50% to 78% in women and from 50% to 72% in men compared with a random allocation of X-rays. Use of X-rays can be optimized by selecting patients at high risk using a short screening procedure.

INTRODUCTION

Previous osteoporotic fracture is an independent risk factor for further fractures and an indication for treatment. Vertebral fractures are the most common osteoporotic fractures before age 75, accounting for 48% of all fractures in men and 39% in women over 50. They usually remain unrecognized, so many patients requiring treatment are denied it, doubling their risk of a further fracture. Our objective was to develop an efficient algorithm indicating the need for an X-ray.

MATERIALS AND METHODS

Data from 2908 women and 2653 men >or=50 years of age in the European Prospective Osteoporosis Study (EPOS) were analyzed. Lateral thoracic and lumbar spine radiographs were taken at baseline and at an average of 3.8 years later. Prevalent fractures were qualitatively diagnosed by an experienced radiologist. Fracture risk was modeled as a function of age, statural height loss since age 25, gender, and fracture history including limb fractures in the last 3 years using negative binomial regression. Receiver operating characteristic (ROC) curves were used to summarize a model's predictive ability, and a prediction algorithm was devised to identify those most likely to have a fracture.

RESULTS

In a multivariate model for women, the risk of prevalent vertebral fracture significantly increased with age (RR, 1.67 [95% CI, 1.46, 1.93] per decade), statural height loss (1.06, [1.03, 1.10] per centimeter decrease), self-reported history of spine fracture (7.52 [5.52, 10.23]), and history of other major fracture (1.83 [1.46, 2.28]). Higher body weight reduced risk (0.86 [0.79, 0.95] per 10-kg increase). In men, the respective RR estimates were as follows: age (1.32 [1.18, 1.49]); height loss (1.06 [1.04, 1.09]); self-reported spine fracture (5.05 [3.69, 6.90]); other major fracture (1.42 [1.12, 1.81]); and weight (0.86 [0.79, 0.94]). Using algorithms based on these easily elicited determinants, specificity was increased from 50% to 78% in women and from 50% to 72% in men at a sensitivity of 50% compared with a random allocation of X-rays. At a sensitivity of 75%, the specificity was 50% in women and 40% in men. Inclusion of hip BMD (femoral neck or trochanter), measured in 1360 women and 1046 men, significantly improved the area under the ROC curves by 4% in women (p < 0.002) but not in men (p > 0.350). Spine BMD, measured in 982 women and 847 men, produced a significant 5% AUC improvement in women (p = 0.007) but not in men (p = 0.554).

CONCLUSION

A woman 65 years of age with one vertebral fracture has a one in four chance of another fracture over 5 years, which can be reduced to one in eight by treatment. Positive treatment decisions are often contingent on identifying a vertebral fracture. Selective use of lateral vertebral X-rays can be optimized using a 2-minute screening procedure administered by a nurse.

Recognizing and reporting osteoporotic vertebral fractures

Vertebral fractures are the hallmark of osteoporosis, and occur with a higher incidence earlier in life than any other type of osteoporotic fractures. It has been shown that both symptomatic and asymptomatic vertebral fractures are associated with increased morbidity and mortality. Morbidity associated with these fractures includes decreased physical function and social isolation, which have a significant impact on the patient's overall quality of life. Since the majority of vertebral fractures do not come to clinical attention, radiographic diagnosis is considered to be the best way to identify and confirm the presence of osteoporotic vertebral fractures in clinical practice. Traditionally, conventional lateral radiographs of the thoracolumbar spine have been visually evaluated by radiologists or clinicians to identify vertebral fractures. The two most widely used methods to determine the severity of such fractures in clinical research are the semiquantitative assessment of vertebral deformities, which is based on visual evaluation, and the quantitative approach, which is based on different morphometric criteria. In our practice for osteoporosis evaluation we use the Genant semiquantitative approach: an accurate and reproducible method tested and applied in many clinical studies. The newest generation of fan-beam DXA systems delivering "high-resolution" lateral spine images offers a potential practical alternative to radiographs for clinical vertebral fracture analysis. The advantages of using DXA over conventional radiographic devices are its minimal radiation exposure and high-speed image acquisition. It also allows combined evaluation of vertebral fracture status and bone mass density, which could become a standard for patient evaluation in osteoporosis. The disadvantage of DXA use is that upper thoracic vertebrae cannot be evaluated in a substantial number of patients due to poor imaging quality. We truly believe that the that there is a major role for radiologists and clinicians alike to carefully assess and diagnose vertebral fractures using standardized grading schemes such as the one outlined in this review. Quantitative morphometry is useful in the context of epidemiological studies and clinical drug trials; however, the studies would be flawed if quantitative morphometry were to be performed in isolation without additional adjudication by a trained and highly experienced radiologist or clinician.