Position StatementVertebral Fracture Assessment: The 2005 ISCD Official Positions
Introduction
Vertebral fractures are common 1, 2, 3, 4, 5, 6, 7 yet often unrecognized clinically, with only about one third of vertebral fractures found on radiographs coming to clinical attention (8). Yet the presence of prior vertebral fractures, even those that are not diagnosed clinically, is a significant risk factor for future vertebral, and to a lesser degree non-vertebral, fractures 9, 10, 11, 12, 13. Thus, finding vertebral fractures identifies patients with increased skeletal fragility. Because of this, the National Osteoporosis Foundation (NOF) has recommended that the presence of vertebral fractures, unless they result from trauma or pathologic process, be considered diagnostic of osteoporosis and treated aggressively (14). Furthermore, the presence of vertebral fractures increases fracture risk independent of bone mineral density (BMD) (15). Thus, concurrent information on bone mass and vertebral fracture status aids clinicians in stratifying fracture risk and evaluating the need for osteoporosis therapy. Since diagnosing vertebral fractures has traditionally required radiographs, which are often not obtained when evaluating patients for osteoporosis, many of these fractures are not discovered and not considered when selecting patients for treatment.
Vertebral fracture assessment (VFA) is a method for imaging the thoraco-lumbar spine using bone densitometers (16). It can easily be performed at the time of BMD measurement, allowing integration of BMD and vertebral fracture information in the clinical care of patients evaluated for osteoporosis. VFA is associated with low radiation exposure (3 μSv vs. 600 μSv for spine radiographs), and can be obtained within seconds or minutes during a densitometry examination. However, VFA is a relatively new procedure which has received limited evaluation in research studies 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, and has previously not been widely used in clinical settings.
Theoretically, this new method of spine imaging could be offered to all patients who present for densitometry; however, several areas of uncertainty exist regarding the clinical application of VFA. Importantly, it is necessary to establish which patients should receive VFA in order to identify those with vertebral fractures, while minimizing testing of individuals who do not have vertebral fractures. Additionally, it is not clear which methodology is best to utilize for diagnosis of vertebral fractures using VFA. This is not surprising, as even for spine radiographs, which have been the ‘gold standard’ to identify vertebral fracture for many years, there is continuing debate regarding the relative merits of visual versus morphometric assessment, or different combinations of the two 9, 30, 31, 32, 33, 34, 35, 36. Finally, due to its lower resolution, VFA does not provide the image quality of conventional radiography. Consequently, in some instances, VFA is not able to precisely characterize some vertebral fractures or other bone and soft tissue abnormalities. In these situations other imaging examinations may be needed to clarify the VFA findings: however, the VFA findings necessitating further imaging have not been adequately defined.
Section snippets
Methodology
The methods used to develop, and grading system applied to these ISCD Official Positions, are presented in the Executive Summary that accompanies this paper. In brief, all Positions were graded on quality of evidence (good, fair, poor), strength of the recommendation (A, B, or C, where A is a strong recommendation supported by the evidence, B is a recommendation supported by the evidence, and C is a recommendation supported primarily by expert opinion), and applicability (worldwide or variable
ISCD Official Position
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Vertebral Fracture Assessment (VFA) is the correct term to denote densitometric spine imaging performed for the purpose of detecting vertebral fractures.
Grade: Poor-C-1
Rationale & Discussion
Vertebral Fracture Assessment, with the acronym VFA, is the preferred designation for this procedure. Several other terms have previously been used in the literature, including vertebral absorptiometry or MXA (morphometric x-ray absorptiometry) 17, 18, 20, 21, 22, 23, 24, 25, 29, 37, 38, Instant Vertebral Assessment (IVA) (19), Radiographic Vertebral Assessment (RVA), Lateral Vertebral Assessment (LVA) (28), Dual-energy Vertebral Assessment (DVA) (27) and others. IVA and RVA are terms specific
ISCD Official Position
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Consider VFA when the results may influence clinical management.
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When BMD measurement is indicated, performance of VFA should be considered in clinical situations that may be associated with vertebral fractures. Examples include:
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Documented height loss of greater than 2 cm (0.75 in) or historical height loss greater than 4 cm (1.5 in) since young adult.
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History of fracture after age 50.
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Commitment to long-term oral or parenteral glucocorticoid therapy.
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History and/or findings suggestive of vertebral
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Rationale
Because VFA is a simple, fast, low radiation method for imaging the spine, it could theoretically be performed in all patients who present for central BMD measurement. However, as with any test used in clinical medicine, it should only be offered to patients whose care is likely to be influenced by the results. As such, in developing indications for VFA, the ISCD aimed to identify populations that are at high risk for vertebral fractures. Insights to identify such individuals are available from
Discussion
Examples of clinical situations in which VFA is appropriate include:
Example 1. Documented height loss of >2 cm (0.75 in) or historical height loss of >4 cm (1.5 in) since young adult.
While some height loss is commonly seen with aging, height loss (defined here as measured current height minus recalled young-adult height), exceeding 4 cm, is two to three times more likely to occur in subjects with vertebral deformities than in those without, with progressively greater height loss occurring in
ISCD Official Position
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The methodology utilized for vertebral fracture identification should be similar to standard radiological approaches, and be provided in the report.
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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.
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The severity of vertebral fractures may be determined using the semiquantitative (SQ) assessment criteria developed by Genant.∗ Severity of deformity may be confirmed by
Rationale & Discussion
The method used for diagnosing vertebral fractures remains an ongoing subject of debate, even for interpreting radiographs. Large population studies have used morphometric approaches with different ways of defining vertebral fractures 3, 95, 96, 97, 98. However, morphometric methods have drawbacks when being considered for use in VFA. Specifically, they are cumbersome to apply indiscriminately to all vertebrae in routine clinical practice. Additionally, and importantly, purely morphometric
ISCD Official Position
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The decision to perform additional imaging must be based on each patient's overall clinical picture including the VFA result.
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Consider additional imaging when there are:
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Equivocal fractures.
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Unidentifiable vertebrae between T7-L4.
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Sclerotic or lytic changes, or findings suggestive of conditions other than osteoporosis.
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Note: VFA is designed to detect vertebral fractures and not other abnormalities.
Grade: Poor-C-1
Rationale & Discussion
Since there are no studies that examine when VFA should be followed by another imaging modality, the recommendations given in the introduction are based on expert opinion. It is important to consider the overall clinical care of the patient in making the decision for further testing. The instances below are examples of possible situations where additional imaging may be useful:
- a.
Equivocal fractures
- b.
Unidentifiable vertebrae between T7-L4
- c.
Finding a bone abnormality such as a sclerotic or lytic
ISCD Official Position
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Patient identification, referring physician, indication(s) for study, technical quality, and interpretation.
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A follow-up VFA report should also include comparability of studies and clinical significance of changes, if any.
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Optional components include fracture risk and recommendations for additional studies.
Rationale
An appropriate VFA report should include information that identifies the patient, assists the interpreter in evaluating the scan, conveys the validity of the study, and provides clear scan interpretation and recommendations where appropriate.
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Information needed for VFA reports include:
- a.
Demographic information (name, medical record identifying number, date of birth, sex, age, height, and weight)
- b.
Requesting physician and other relevant healthcare providers
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Indications for the study
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Medical history and
- a.
In Summary
The ISCD Official Positions on VFA represent an effort to create order in the use of a newly developed technology that has important clinical implications. It is likely that these positions will evolve over time as new data become available. Further research, designed to address issues that may emerge through the course of clinical use, should be undertaken to expand the body of knowledge and move the field of clinical densitometry forward.
Acknowledgments
The following served as advisors/consultants during the VFA subcommittees work in developing these Official Positions:
Richard Eastell, M.D., FRCP, FRCPath, FMedSci, University of Sheffield Clinical Sciences Ctr, Sheffield, S Yorkshire, UK.
Harry Genant, M.D., Ph.D., University Of California, San Francisco, CA, USA.
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