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Clinical Applications of Vertebral Fracture Assessment by Dual-Energy X-Ray Absorptiometry

New Mexico Clinical Research and Osteoporosis Center (E.M.L.), Albuquerque, New Mexico 87106; and Arthritis and Osteoporosis Consultants of the Carolinas (A.J.L.), Charlotte, North Carolina 28207

Address all correspondence and requests for reprints to: E. Michael Lewiecki, M.D., F.A.C.P., New Mexico Clinical Research, Osteoporosis Center, 300 Oak Street NE, Albuquerque, New Mexico 87106. E-mail: lewiecki{at}aol.com.

	Abstract

Top Abstract Introduction Imaging of the Spine Indications for VFA Diagnosis of VFs with... Cost Effectiveness of VFA Pharmacological Therapy Based on... Additional Imaging after VFA Quality Issues with VFA Conclusion Addendum: ISCD Official... References

 
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.

	Introduction

Top Abstract Introduction Imaging of the Spine Indications for VFA Diagnosis of VFs with... Cost Effectiveness of VFA Pharmacological Therapy Based on... Additional Imaging after VFA Quality Issues with VFA Conclusion Addendum: ISCD Official... References

 
OSTEOPOROSIS IS A common disease that causes no symptoms until a fracture occurs. Fractures of the hip (1) and limbs (2) usually occur after a fall, resulting in severe pain that motivates patients to seek immediate medical attention. Vertebral fractures (VFs), however, commonly occur with no recognizable trauma (3) and may not cause pain of sufficient magnitude to arouse the concern of the patient or physician (4). VFs are the most common type of fragility fracture (5), with 5% of 50-yr-old Caucasian women and 25% of 80-yr-old women having at least one VF (6). Only about one third of all radiographic VFs come to clinical attention (7), more commonly in men (42%) than women (22%) (8). Fractures of the spine are associated with reduced pulmonary function (9, 10, 11), chronic back pain (12, 13), loss of height (12), kyphosis (14), loss of self-esteem (4), abdominal discomfort (4), disability (15), loss of independence (15), and death (16, 17, 18, 19).

The mortality rate 5 yr after a clinical VF is about 20% greater than expected (20), with mortality rates higher for men than women (21). Mortality rates increase with the number of VFs (18). New VFs, even those that are not recognized clinically (i.e. morphometric fractures), are associated with substantial increases in back pain and functional limitations (22). The presence of a VF increases the relative risk of future VFs by about 4.4-fold and increases the risk of fragility fractures at other skeletal sites as well (23). The greater the number of prevalent VFs, the greater the risk of future VFs (24). A new VF is associated with a 19% risk of another VF in the next 12 months (25). The greater the severity of prevalent VFs, the greater the risk of future VFs (26). The presence of a VF is a risk factor for future fracture that is independent of bone mineral density (BMD) (27). The National Osteoporosis Foundation recommends that patients with a prior VF receive drug therapy regardless of BMD T-score (28). Currently available pharmacological agents reduce the risk of fractures in high-risk patients (29).

Spine x-rays are often not done in patients with back pain and are very rarely done in those without back pain. Even VFs that are visible on x-rays are commonly not reported by radiologists. In a review of chest x-rays done on women hospitalized at a large regional American facility for a variety of medical disorders, only about half of VFs were noted in the body of the x-ray report and only about half of those were listed in the summary of the x-ray report (30). Underdiagnosis of VFs on spine x-rays has been observed worldwide, with false-negative interpretation rates of about 45% in North America, 46% in Latin America, and 29% in Europe/South Africa/Australia (31). With increasing recognition of the clinical significance of prevalent VFs as a risk factor for future fractures, new clinical tools to enhance the ability of healthcare providers to detect previously unrecognized VFs have been developed. This review focuses on the technology and clinical utility of spine imaging with VF assessment (VFA) by dual-energy x-ray absorptiometry (DXA) for the diagnosis of VFs.

	Imaging of the Spine

Top Abstract Introduction Imaging of the Spine Indications for VFA Diagnosis of VFs with... Cost Effectiveness of VFA Pharmacological Therapy Based on... Additional Imaging after VFA Quality Issues with VFA Conclusion Addendum: ISCD Official... References

 
Methods to detect and evaluate VFs in clinical practice include plain radiography (x-ray), computed tomography (CT), magnetic resonance imaging (MRI), nuclear bone scanning, and VFA. There are differences in each of these in terms of image resolution, radiation exposure, availability, cost, and patient convenience (Table 1). Spine x-rays are commonly obtained in the initial evaluation of back pain when a skeletal etiology is suspected. Whereas the resolution is good and it is widely available at a modest cost, there is significant radiation exposure and occasional inconvenience to the patient in scheduling and travel to a facility with x-ray capability. If a fracture is detected, a CT or MRI study may be done to define the anatomy, especially when vertebroplasty or kyphoplasty is being considered. CT scanning gives excellent image resolution but is less available, more costly, more inconvenient, and involves greater radiation exposure than standard radiography. MRI is helpful to evaluate for diseases other than osteoporosis that may be responsible for the fracture (e.g. malignancy) and estimate the time since the fracture occurred. Image resolution is excellent and there is no ionizing radiation, but availability may be limited, the cost is high, and patient inconvenience (e.g. scheduling, travel time, claustrophobia) may be an issue. Nuclear bone scanning can provide information about the age of the fracture and may show abnormalities from other skeletal disorders but has poor resolution, high cost, exposure to radiation, and sometimes poor availability and high patient inconvenience. VFA offers point-of-service convenience for the patient when it is done at the same visit as for BMD measurement by DXA, with far less radiation than standard radiography. The effective radiation dose for VFA is about 3 micro-Sieverts (µSv) vs. 600 µSv for a lateral lumbar spine x-ray (32). By comparison, typical background radiation at sea level in the United States is about 7 µSv/d (33). Image resolution is superior to nuclear bone scanning but not as good as with standard radiography, CT, or MRI. In comparison with standard spine x-ray imaging, visualization of thoracic spine levels above T7 is not as reliable with VFA, although the ability to view the entire spine in one image without cone beam distortion (34) is an advantage with VFA. The age of the fracture cannot be determined by VFA, spine radiography, or CT unless prior imaging is available for comparison.

Performance of VFA requires a fan-beam DXA system with appropriate software installed. It may be done in either single-energy or dual-energy mode, with the patient in a lateral decubitus or supine lateral position with a rotary C-arm, depending on the manufacturer and model of instrument. VFA computer programs allow for image manipulation (magnification, contrast, brightness) that enhances visualization of vertebral deformities. Manual or automated placement of point markers at the anterior, middle, and posterior margins of the vertebral endplates is a convenient tool for ease of measurement of vertebral body heights and ratios. Images of the spine may be viewed on a computer monitor or as a printout. Side-by-side viewing of previous and recent VFA images aids in the evaluation of vertebral changes for detection of incident VFs.

	Indications for VFA

Top Abstract Introduction Imaging of the Spine Indications for VFA Diagnosis of VFs with... Cost Effectiveness of VFA Pharmacological Therapy Based on... Additional Imaging after VFA Quality Issues with VFA Conclusion Addendum: ISCD Official... References

 
The clinical utility of VFA had led many to recommend its usage as a complement to BMD testing to identify those patients most likely to benefit from pharmacological therapy (34, 50, 54, 55), especially those with osteopenia and no other risk factors for fracture who might otherwise not be treated. As with any medical test, VFA should not be done unless the results may influence patient management. If a diagnosis of VF from VFA is not likely to alter the decision to treat or not to treat, change the drug selected for treatment, or affect the follow-up of the patient, then VFA should not be done. The ISCD has addressed the indications for VFA (see Addendum) by citing examples of clinical situations in which patients are at high risk of VF but might not be treated based on BMD and other clinical risk factors for fracture (32). Examples of high-risk patients are those with historical height loss (HHL), the difference between a patient’s highest recalled height and current measured height, greater than 4 cm (1.5 inches), or measured height loss greater than 2 cm (0.75 inches). Although loss of height may occur for reasons other than VFs, such as postural changes and degenerative disk disease associated with aging, HHL exceeding 4 cm has been associated with an almost 3-fold increase in the risk of prevalent VF. The ISCD-recommended HHL cutoff of 4 cm is supported by its association with an odds ratio for VF of 2.8 [95% confidence interval (CI) 2.2–3.6] in women in the Study of Osteoporotic Fractures (13) and 2.9 (95% CI 2.6–3.3) in women screened for the Fracture Intervention Trial (56). Others have proposed HHL greater than 6 cm as an indicator for spine imaging, based on a likelihood ratio of 2.8 (95% CI 1.3–6.0), sensitivity of 30% and specificity of 94% for prevalent VF in postmenopausal women (57). In the placebo arm of a clinical trial for an antiresorptive agent in postmenopausal women, it was found that measured height loss of greater than 2 cm over 3 yr was associated with a 35.5% sensitivity and 93.6% specificity for new VFs (58).

Previous fracture (23) and long-term glucocorticoid therapy (59) are both robust predictors of future fracture independently of BMD. Kyphosis is a risk factor for future VFs, regardless of whether the kyphosis is caused by previous VFs (60). This suggests that altered load-bearing properties of vertebral bodies or increased risk of falling due to kyphosis may play a role in fracture risk. Treatment guidelines of U.S.-based organizations typically recommend pharmacological therapy when the BMD T-score is below a cutoff of –2.0 (or –2.5) or when the T-score is between –1.5 and –2.0 (or –2.5) and clinical risk factors for fracture are present (28, 62, 63, 64). VFA may influence management of patients who have T-scores in this range and no clinical risk factors for fracture because a diagnosis of VF would lead to treatment that would otherwise not be given. Situations may arise when VFA-diagnosed VFs influence the choice of therapy by placing the patient in a higher risk category that justifies consideration of more aggressive therapy, e.g. anabolic instead of anticatabolic therapy.

Defining and reporting fractures from VFA

The ideal VF definition would be standardized worldwide, accepted by all medical specialties, apply to any imaging technology, and clearly distinguish a VF from a nonfracture deformity. No currently available diagnostic methodology meets all of these criteria. Vertebral deformities may be due to osteoporotic VFs, traumatic VFs, surgical artifact, congenital variations, osteoarthritis, and many other factors. The distinction between physiological and pathological vertebral height loss is not clear. When a VF is present, vertebral height may change rapidly with changes in patient positioning due to dynamic mobility (65), worsen with evolution of the fracture (66), or possibly even improve spontaneously over time (67). Whereas the most severe VFs are the easiest to recognize with imaging and have the most serious clinical consequences, the opportunity to identify high-risk patients before major fractures occur depends on recognizing milder fractures. A method of diagnosis that is overly sensitive will have a high rate of false positives (nonfracture deformities incorrectly classified as VFs), possibly resulting in patients receiving unnecessary treatment. If a method is not sensitive enough, there will be excessive false negatives (failure to diagnose VFs when present), resulting in failure to identify a patient at high risk for future fracture who might benefit from pharmacological intervention.

Strategies to diagnose VFs can be divided into categories of quantitative (morphometric, by measurement), semiquantitative (SQ; combination of morphometric and visual assessment), and qualitative (visual assessment only). Morphometric methods are often used in population studies and some clinical trials but may be overly cumbersome and time consuming in clinical practice. Exclusive dependence of vertebral morphometry may result in both false positives and false negatives (68). An experienced observer can effectively recognize VFs with visual inspection, but exclusive use of this technique is overly subjective and associated with high interobserver variability (68). Visual inspection combined with morphometry, when appropriate, has been recognized by the ISCD as the preferred method for diagnosing VFs (see Addendum). SQ techniques can be easily applied in clinical practice and have been validated by comparison with other methods (70). The Genant SQ methodology has been used successfully in clinical trials and clinical practice for many years (71). This method classifies VFs as grade 1 or mild (20–25% loss of vertebral height), grade 2 or moderate (25–40% loss of vertebral height), and grade 3 or severe (greater than 40% loss of vertebral height). Other methods for diagnosing VFs may be equally valid (32). Whatever method is used to diagnose VFs, it should be clearly stated in the VFA report.

	Diagnosis of VFs with VFA, Compared with Standard Spine Radiography

Top Abstract Introduction Imaging of the Spine Indications for VFA Diagnosis of VFs with... Cost Effectiveness of VFA Pharmacological Therapy Based on... Additional Imaging after VFA Quality Issues with VFA Conclusion Addendum: ISCD Official... References

 
Numerous studies have shown that VFA compares favorably with standard spine radiographs in detecting VFs using the Genant SQ method (41, 52, 54, 72) or other methods for defining VFs (35, 36, 37, 38, 39, 73). In a study of the reliability and accuracy of VFA with the Genant SQ method in women age 65 yr and older, it was found that the sensitivity of VFA for diagnosing moderate (grade 2) and severe (grade 3) VFs was 87–93%, with a specificity of 93–95% (72). VFA did not perform well for diagnosing mild (grade 1) VFs or in the presence of scoliosis or moderate/severe disk space osteoarthritis. These findings are consistent with other studies showing the difficulties of diagnosing VFs that are mild (52, 54) or associated with structural deformities of the spine due to scoliosis (41) or osteoarthritis (74). Strategies to manage these issues include disregarding suspected mild VFs, which are of much less clinical significance than those that are moderate or severe (26); obtaining an anterior-posterior view of the spine by VFA as well as a lateral view to identify patients with scoliosis (72); and following VFA with spine radiography in selected patients with suspected vertebral deformities (72).

It is important to note that spine radiographs also have limitations in the evaluation of VFs, especially for grade 1 fractures. In the international multicenter Improving Measurements of Persistence on Actonel Treatment (IMPACT) study, lateral x-rays of the thoracic and lumbar spine in 2451 postmenopausal women were interpreted by local radiologists according to a standardized procedure manual using the Genant SQ method (31). The results were compared with central readings by staff radiologists (the reference standard). The false-negative interpretation rate (x-rays read as no fracture when a fracture was present) was 34% globally (range 29.5–46.5%, depending on world region), with the highest false-negative rate observed with grade 1 VFs (56%, compared with 36% for grade 2 and 9% for grade 3). Osteoarthritis may also limit the ability to diagnose VFs by x-ray (74)

Interobserver agreement in the diagnosis of VFs by VFA and spine radiography has been assessed with readers of differing levels of expertise in patient groups with varying likelihood of VF, using different diagnostic methodologies. In a study by Schousboe and DeBold (72), two nonradiologist observers with VFA experience evaluated 2652 vertebrae in 205 women aged 65 yr and older who were referred to a bone densitometry clinic. Using the Genant SQ method in a per-person analysis, it was found that kappa (K) scores were higher, indicating better interobserver agreement, with grade 2–3 VFs [K = 0.629 for VFA and 0.784 for radiography, both values representing "substantial agreement" (75)], compared with all (grade 1–3) VFs (K = 0.513 for VFA and 0.532 for radiography, both representing "moderate" agreement). In a study of 70 women with known osteoporosis, interobserver agreement of a radiologist and a clinician with expertise in osteoporosis was compared for VFA (with morphometric and visual analysis) and spine radiography (76). There was "almost perfect agreement" (75) (K = 0.86) between the radiologist and clinician using VFA, suggesting that a nonradiologist with appropriate training may be able to make effective use of VFA. There was a similar level of agreement in visual assessment using spine radiographs (K = 0.86). In an evaluation of 136 postmenopausal women having both VFA and spine radiography, the diagnostic efficacy of VFA was 97% with substantial interobserver agreement (K score = 0.69) (77).

	Cost Effectiveness of VFA

Top Abstract Introduction Imaging of the Spine Indications for VFA Diagnosis of VFs with... Cost Effectiveness of VFA Pharmacological Therapy Based on... Additional Imaging after VFA Quality Issues with VFA Conclusion Addendum: ISCD Official... References

 
Although pharmacological therapy can reduce fracture risk in patients at low risk for fracture (those without known low BMD or clinical risk factors), as demonstrated with estrogen and estrogen plus progestin in the Women’s Health Initiative (78, 79, 80), treatment of all low-risk patients may not be cost effective or safe. The Osteoporosis Research Advisory Group performed a metaanalysis of randomized controlled trials for the treatment of postmenopausal osteoporosis (29). This showed that the number needed to treat with a bisphosphonate to prevent a VF is about 25-fold greater for low risk patients (normal BMD with 2-yr untreated VF risk = 0.12%) than high-risk patients (low BMD with 2-yr untreated VF risk = 2.88%). For example, to prevent a VF with alendronate, 1790 low-risk patients must be treated, compared with 72 high-risk patients.

It is clearly most cost effective to identify and treat the high-risk patients. Whereas the interpretation of cost effectiveness analyses must be tempered by recognition of the subjective nature of the numerous modeling assumptions that are used, they nevertheless provide insight into potential clinical applications of VFA. An analysis using a Markov cost-utility model with eight health states concluded that alendronate treatment was not cost effective in postmenopausal women with femoral neck T-scores better than –2.5 and no history of clinical fractures or BMD-independent clinical risk factors for fracture (82). In a related study, a Markov cost-utility model was used to evaluate spine imaging to identify postmenopausal women aged 60 yr and older with prevalent vertebral deformities, comparing three treatment strategies: alendronate treatment for all patients regardless of prevalent vertebral deformities, alendronate treatment only for those with prevalent vertebral deformities, and no drug therapy (83). Lifetime direct and indirect medical costs, quality-adjusted life-years, and incremental cost-effectiveness ratios were considered. With the assumptions used in this analysis, it was likely to be cost effective to perform spine radiography in postmenopausal women with T-scores of –1.5 or below and treat those women with one or more prevalent vertebral deformities.

VFA, which is less expensive than spine radiography and similar in its ability to diagnose VF, is likely to be even more cost effective. Another modeling study concluded that VFA with selective confirmatory radiographic imaging of the spine is cost effective, assuming that society is willing to spend $50,000 per quality adjusted life year gained, for postmenopausal women aged 60–80 yr with femoral neck T-scores between –2.0 and –2.4, and women aged 60 or 70 yr with a femoral neck T-score of –1.5 (84). In a review of 2155 VFA studies in patients aged 65 yr and older with at least 1.5 in. documented height loss, 22% of patients were found to have VFs (using quantitative morphometric vertebral analysis), with 7% having a change in risk stratification and therapeutic recommendations (85). This was accomplished at a cost of $140 per VF diagnosed. It was concluded that combining DXA and VFA provides essential diagnostic and therapeutic information at a nominal cost. An example of the lower cost of VFA, compared with spine radiography, is the estimated 2006 Medicare reimbursement in Los Angeles, CA. At a free-standing imaging facility or physician office, VFA [Current Procedural Terminology (CPT) code 76077] reimbursement is $40.48 vs. $84.94 for thoracic and lumbar spine x-rays (CPT codes 72070 and 72100) (86).

	Pharmacological Therapy Based on VFs Diagnosed by VFA

Top Abstract Introduction Imaging of the Spine Indications for VFA Diagnosis of VFs with... Cost Effectiveness of VFA Pharmacological Therapy Based on... Additional Imaging after VFA Quality Issues with VFA Conclusion Addendum: ISCD Official... References

 
Most osteoporosis treatment guidelines agree that patients with a densitometric diagnosis of osteoporosis (T-score –2.5) are likely to benefit from pharmacological therapy and that those with a T-score greater than –1.5 are unlikely to benefit (87). Treatment may be recommended for patients with T-scores between –1.5 and –2.5 and clinical risk factors for fracture, although the risk factors to consider vary according to the guideline. The World Health Organization effort to establish cost-effective intervention thresholds based on estimated fracture probability and cost-utility analysis enhances the selection of patient most likely to benefit from therapy (88) but may overlook patients with undiagnosed VFs who are at high risk for fracture.

The primary clinical utility of VFA is the identification of patients with undiagnosed VFs who are at high risk for fracture but would otherwise not be selected for treatment. In a study of 482 postmenopausal women aged 65 yr and older with no prior knowledge of VFs who were screened for an osteoporosis clinical trial, VFA revealed that 18% had one or more VFs (50). Of the patients who had a densitometric diagnosis of osteopenia or normal (using the lowest T-score of the lumbar spine, total hip, or femoral neck), 18 and 13%, respectively, were reclassified to a clinical diagnosis of osteoporosis due to the presence of VF observed by VFA. Without VFA-acquired knowledge of VFs, these women would have received an incorrect diagnostic classification and underestimation of fracture risk. If these women had been seen in clinical practice without VFA being done, they might not have been considered for potentially beneficial pharmacological therapy. The authors of this study concluded that VFA is a useful tool for the management of osteoporotic patients.

Fractures commonly occur in patients with T-scores above –2.5. In a prospective cohort study of 671 postmenopausal women having periodic spine imaging, 48% of VFs occurred in those with osteopenic T-scores (between –1.0 and –2.5) (89). The age-adjusted hazard ratio for future fracture was 2.2 (1.2–4.3) in those with previous fracture, suggesting that reliance on BMD alone misses many women at high risk of fracture who might benefit from therapeutic intervention. In the Rotterdam prospective observational study of 7806 men and women, it was found that 79% of nonvertebral fractures in men were in those with a femoral neck T-score above –2.5, with 66% of nonvertebral fractures in women occurring in those with a femoral neck T-score above –2.5 (90, 91). In the Study of Osteoporotic Fractures, 8065 postmenopausal women were followed up for least 5 yr after baseline BMD testing. It was found that 54% of hip fractures were in women with total hip T-scores above –2.5 (81).

Randomized, placebo-controlled clinical trials have demonstrated that treatment of patients with osteopenic T-scores and prevalent VFs reduces the risk of future fractures. In pooled data from the Vertebral Efficacy with Risedronate Therapy Multinational and North American trials, there was a significant reduction in incident VFs in women who entered the study with a prevalent VF and T-score greater than –2.5 (69). In the Fracture Intervention Trial, alendronate reduced the risk of VF in women with prevalent VFs and T-scores between –1.6 and –2.5 (61). In other studies with ibandronate (53), raloxifene (49), and teriparatide (48), patients recruited solely on the basis of prevalent VF without a requirement to have a densitometric classification of osteoporosis had a reduction in fracture risk with treatment. The finding that patients with osteopenic T-scores and prevalent VFs can benefit from therapy by reduction in fracture risk completes the chain of logic that provides the rationale for the use of VFA in clinical practice (Table 2).

	Additional Imaging after VFA

Top Abstract Introduction Imaging of the Spine Indications for VFA Diagnosis of VFs with... Cost Effectiveness of VFA Pharmacological Therapy Based on... Additional Imaging after VFA Quality Issues with VFA Conclusion Addendum: ISCD Official... References

	Quality Issues with VFA

Top Abstract Introduction Imaging of the Spine Indications for VFA Diagnosis of VFs with... Cost Effectiveness of VFA Pharmacological Therapy Based on... Additional Imaging after VFA Quality Issues with VFA Conclusion Addendum: ISCD Official... References

 
A bone densitometry facility that is performing VFA must be aware of the indications for VFA, have DXA systems that are maintained according to the manufacturer’s recommendations, use staff that are skilled in performing VFA, and have knowledgeable clinicians interpreting the results. The technologist should have a thorough understanding of proper positioning of the patient and analysis of the image. The interpreter should be familiar with the utility and the limitations of VFA and communicate the findings in the report (see Addendum). Some specialists (e.g. musculoskeletal radiologists) have extensive training in the diagnosis of VFs and have no difficulty interpreting VFA images. Nonradiologists who commonly interpret BMD measurements at bone densitometry facilities may not be skilled at diagnosing VFs and may not be aware of normal variations in spine curvature and variations in the size and shape of vertebral bodies. For example, physiological cupping of lumbar vertebral endplates or physiological wedging of thoracic vertebral endplates may occur as normal variants and if not recognized as such, could lead to an inappropriate diagnosis of VF and possibly unnecessary treatment. If quantitative morphometry is used, correct placement of point markers must be validated by a skilled interpreter, because point placement may be problematic in the presence of obliquity of the image, scoliosis, degenerative disc disease, osteophytes, or surgical artifact. VFA training for technologists and clinicians is available from organizations such as the ISCD, with information available on their web site (www.iscd.org). Validation of expertise in the acquisition and interpretation of VFA would be enhanced by the development of certification programs, similar to what is now provided by the ISCD for bone densitometry.

	Conclusion

Top Abstract Introduction Imaging of the Spine Indications for VFA Diagnosis of VFs with... Cost Effectiveness of VFA Pharmacological Therapy Based on... Additional Imaging after VFA Quality Issues with VFA Conclusion Addendum: ISCD Official... References

 
VFs are the most common type of fragility fracture yet are often not clinically recognized. They are associated with significant morbidity and mortality and increased risk of future fracture, independently of BMD. Recognition of VFs by imaging of the spine may change a patient’s diagnostic classification, estimation of fracture risk, and threshold for pharmacological intervention. Treatment of patients with prevalent VFs reduces the risk of future fractures, even when the baseline T-score is above the osteoporosis diagnostic cut point of –2.5. VFA is a technology than can reliably and accurately diagnose VFs with greater patient convenience, less radiation exposure, and lower cost than standard spine radiography.

	Addendum: ISCD Official Positions on VFA (32)

Top Abstract Introduction Imaging of the Spine Indications for VFA Diagnosis of VFs with... Cost Effectiveness of VFA Pharmacological Therapy Based on... Additional Imaging after VFA Quality Issues with VFA Conclusion Addendum: ISCD Official... References

 
VFA nomenclature

VFA is the correct term to denote densitometric spine imaging performed for the purpose of detecting VFs.

Indications for VFA

Consider VFA when the results may influence clinical management.

When BMD measurement is indicated, performance of VFA should be considered in clinical situations that may be associated with VFs. Examples include:

Documented height loss of greater than 2 cm (0.75 in) or HHL greater than 4 cm (1.5 in.) since young adult.

History of fracture after age 50 yr.

Commitment to long-term oral or parenteral glucocorticoid therapy.

History and/or findings suggestive of VF not documented by prior radiologic study.

Method for defining and reporting fractures on VFA

The methodology used for VF identification should be similar to standard radiological approaches and be provided in the report.

Fracture diagnosis should be based on visual evaluation and include assessment of grade/severity. Morphometry alone is not recommended because it is unreliable for diagnosis.

The severity of VFs may be determined using the SQ assessment criteria developed by Genant (71). Severity of deformity may be confirmed by morphometric measurement if desired.

Indications for following VFA with another imaging modality

The decision to perform additional imaging must be based on each patient’s overall clinical picture including the VFA result.

Consider additional imaging when there are:

Equivocal fractures.

Unidentifiable vertebrae between T7 and L4.

Sclerotic or lytic changes or findings suggestive of conditions other than osteoporosis.

Note: VFA is designed to detect VFs and not other abnormalities.

Components of a VFA report

Patient identification, referring physician, indication(s) for study, technical quality and interpretation.

A follow-up VFA report should also include comparability of studies and clinical significance of changes, if any.

Optional components include fracture risk and recommendations for additional studies.

	Footnotes

 
Disclosure Statement: E.M.L. receives grant support from Merck, Eli Lilly, Novartis, Procter & Gamble, Sanofi Aventis, Amgen, Pfizer, Wyeth-Ayerst, Roche, and GlaxoSmithKline; consults for Merck, Eli Lilly, Novartis, Procter & Gamble, Amgen, Pfizer, Wyeth-Ayerst, Roche, and GlaxoSmithKline; receives lecture fees from Merck, Procter & Gamble, and Roche; has equity interests in GE and Procter & Gamble; and is a member of the ISCD board of directors. A.J.L. consults for Merck, Procter & Gamble, and Eli Lilly; receives lecture fees from Procter & Gamble, Abbott, Eli Lilly, Genentech, Roche, GlaxoSmithKline; and is a member of the ISCD board of directors.

NIH Statement: There was no National Institutes of Health support for this review and neither of the authors is a NIH researcher.

First Published Online August 29, 2006

Abbreviations: BMD, Bone mineral density; CI, confidence interval; CT, computed tomography; DXA, dual-energy x-ray absorptiometry; HHL, historical height loss; ISCD, International Society for Clinical Densitometry; K, kappa; MRI, magnetic resonance imaging; SQ, semiquantitative; VF, vertebral fracture; VFA, VF assessment.

Received May 31, 2006.

Accepted August 22, 2006.

	References

Top Abstract Introduction Imaging of the Spine Indications for VFA Diagnosis of VFs with... Cost Effectiveness of VFA Pharmacological Therapy Based on... Additional Imaging after VFA Quality Issues with VFA Conclusion Addendum: ISCD Official... References

 

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