Imaging can play a critical role in identifying patients who could benefit from pharmaceutical treatments for osteoporosis. So why is it that up to 45% of vertebral fractures, which are visible on radiographs, remain undiagnosed?
The authors of a recent call to action in the American Journal of Roentgenology offer some theories on that question, and urge adoption of a standardized approach toward fracture reporting that they believe will address this shortfall.
Given the likely increase in osteoporosis within the aging populations of Western countries, the future of bone imaging and osteoporosis is also the timely subject of this year's Annual Oration in Diagnostic Radiology at the RSNA meeting in Chicago (PS60).
Dr. Harry Genant of the University of California, San Francisco will deliver the lecture on November 30. Genant also developed the standardized approach to fracture reporting advocated in the AJR review.
The importance of imaging is highlighted by the fact that only about one in four vertebral fractures is recognized clinically, without radiographs.
Yet even one asymptomatic fracture indicates a much greater risk for the patient. Studies have found that having one previous vertebral leads to a fivefold increase in the risk of another vertebral fracture, and a threefold increase in the risk of hip fracture.
By reporting these asymptomatic fractures, radiologists enable a diagnosis of osteoporosis that can lead to pharmacologic therapy and further risk assessment, according to Genant and his AJR co-authors.
But there is evidence of radiology's failure in this area, coming from a multinational study of 2,000 postmenopausal women with osteoporosis that compared the accuracy of local radiographic reports with subsequent central reads.
Despite a strict radiographic protocol that minimized underdiagnosis due to inadequate film quality, the rate of false-negatives for vertebral fractures in the local radiographic reports ranged from 27% to 45% (Journal of Bone Mineral Research, 2001, Vol. 16: supplement, p. S139).
"The investigators concluded that the failure to diagnose vertebral fracture is a worldwide problem due in part to the lack of fracture recognition by radiologists and the use of ambiguous terminology in radiology reports," the AJR authors wrote in summarizing the study (AJR, October 2004, Vol. 183:4, pp. 949-958).
"One explanation may relate to the lack of standardization in the radiologic interpretation of vertebral fractures, especially when attention is not focused specifically on the issue of fracture," the authors continued.
"In this setting, radiologists often fail to recognize or mention many mild and some moderate fractures, or they use terminology that is nonspecific and does not adequately alert the referring clinician to the presence of a vertebral fracture."
Standardization is the solution, argue the AJR authors, who note that little standardization currently exists in either the qualitative or quantitative (e.g., vertebral morphometry) approaches to fracture diagnosis.
The Genant method that they advocate calls for diagnosing a vertebral fracture whenever there is loss of height in the anterior, middle, or posterior dimension of the vertebral body that exceeds 20%.
"If the radiologist cannot decide whether a fracture is present, additional views or additional imaging studies should be recommended," the authors wrote. "A radiologic hedge can adversely affect patient care by preventing a patient who would otherwise benefit from pharmacologic therapy from receiving it."
The authors also pointed out several potential diagnostic pitfalls, including pseudofractures seen on lateral projections of scoliosis and abnormalities in vertebral shape such as cupid's bow, limbus vertebra, and Schmorl's nodes.
Overall, the Genant method is "ideally suited" as a basis for a standardized interpretation of vertebral fractures in clinical practice because it is quicker and easier than morphometric methods, more accurate than nonstandardized qualitative assessment, highly reproducible, and well-known to most clinicians with an interest in osteoporosis, the authors argue.
Indeed, the European Society of Skeletal Radiology and the International Osteoporosis Foundation have already endorsed this approach, the authors note.
In addition, "the same standardized approach to reporting vertebral fractures described previously should be applied to lateral DXA images," the group concluded. However, "many fractures seen on DXA should be confirmed with standard radiographs to exclude the possibility of a pathologic fracture, and patients with indeterminate DXA images (common in the upper thoracic spine) should be referred for radiography."
By Tracie L. Thompson
AuntMinnie.com staff writer
November 23, 2004
Related Reading
Drug for osteoporosis curtails knee arthritis, November 5, 2004
Half of older adults at risk for osteoporosis, U.S. report finds, October 15, 2004
Quantitative sonography not ready for prime time for diagnosing osteoporosis, September 28, 2004
Misread scans often lead to osteoporosis diagnosis in children, March 22, 2004
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