Prevalence of pitfalls in previous dual energy X-ray absorptiometry (DXA) scans according to technical manuals and International Society for Clinical Densitometry. Poster No.: P-0046 Congress: ESSR 2014 Type: Scientific Poster Authors: C. Messina 1, M. Bandirali 2, M. Petrini 2, F. M. Ulivieri 1, L. M. Keywords: DOI: Sconfienza 2, F. Sardanelli 2 ; 1 Milan/IT, 2 San Donato Milanese/IT Musculoskeletal bone, Absorptiometry / Bone densiometry, Diagnostic procedure, Osteoporosis 10.1594/essr2014/P-0046 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. www.essr.org Page 1 of 8
Purpose Osteoporosis is a skeletal disorder characterized by low bone mass and microarchitectural deterioration of bone tissue, determining an increase in bone fragility and predisposition to fragility fractures(1). This disease is commonly evaluated through a quantitative assessment of bone mineral density (BMD), which represents a major determinant of bone strength (2) DXA rests on numerical data. For this reason, is mandatory to strictly apply the instructions provided by densitometer manufacturers in the user's manual as well as the reccomendations of the International Society for Clinical Densitometry (ISCD). In fact, inaccurate DXA exams may result in erroneous data interpretation and equivocal reports (3) In literature, two exhaustive reviews of DXA pitfalls in adults were published in 2004 by Watts (4) and in 2013 by Garg et al (5), reporting some of the most common errors in positioning, scan analysis, and interpretation for both femur and lumbar spine. The aim of this study was to evaluate rate and type of errors in DXA examinations, evaluating a consecutive series of previous DXAs provided by patients presenting at our institution to perform a new DXA. Methods and Materials This retrospective study was approved by the Institutional Review Board. During 2012, 2,476 patients underwent DXA at our institution, a university hospital. Of them, 1,198 patients did not provided any previous DXA examination while 793 patients had had a previous DXA performed at our institution. The remaining 485 patients entered analysis. They were 447 females and 38 males; age was 68±9 years (mean ± standard deviation). A radiologist with four year experience in DXA and osteoporosis management reviewed all DXA scans to check for adherence to correctness criteria according to ISCD guidelines and the users' manual of the main DXA manufacturers (Hologic, Lunar, and Norland). According to Watts et al. (11) and Garg et al. (12), errors were classified in the following four categories: Page 2 of 8
patient positioning (PP): errors related to proper positioning of lumbar spine or femur. data analysis (DA): post-acquisition analysis errors presence of artifacts: presence of artifacts that may alter BMD demographics: inaccuracies in date of birth, gender, and ethnicity, crucial data for the calculation of Z-score and T-score. Data are presented as mean ± standard deviation or as median and interquartile (IQ) range according to their distribution. The presence in each center of a clinical unit dedicated to the diagnosis and treatment of osteoporosis was recorded. Results Previous outsource DXA examination were performed at 37 different centers, with 13±8 patients (mean ± standard deviation) per center. The previous DXA was performed 1 year before in 4.1% of patients, 2 years before in 36.1%, 3 years before in 53.4% or 4 years before in 6.4%. Out of 485 DXA, 451 (93%) had at least one error for a total of 558 errors: 441 (79%) were DA, 66 (12%) PP, 39 (7%) artifacts, and 12 (2%) were demographics. Only 42 (9%) had a DXA with previous comparisons, for a total of 57 errors: 31 (54%) were DA, 17 (30%) PP, and 9 (16%) scan mode discrepancies, 57 errors overall. Further details are reported in Figure 1. Limiting only to 20 centers with at least ten or more DXA examinations, the rate of previous scans with at least one error ranged from 40% to 100%. Among these 20 centers, eight had a clinical unit dedicated to the diagnosis and treatment of osteoporosis. Page 3 of 8
Fig. 1: Details of Errors Detected in Outsource DXA Examinations Performed by 485 Patients References: - Milan/IT Figures 2 to 5 show some of the most common pitfalls we found in our study. Page 4 of 8
Fig. 2: Pitfalls in data analysis of the femur. (A) Femoral neck box misplaced in a Lunar scan, with the neck box also including part of the greater trochanter and the ischium. (B) Femoral neck box misplaced in a Hologic scan: the neck box is not adjacent to the greater trochanter. (C) Very poor bone mapping. References: - Milan/IT Page 5 of 8
Fig. 3: The presence of artifacts may alter bone mineral density (BMD) and T-score. (A) The presence of spine stabilization needles over L2 elevate BMD. (B) A metallic artifact increases the density of soft tissue box, determining a consequent BMD and T- score reduction of the adjacent L1 vertebra. References: - Milan/IT Page 6 of 8
Fig. 4: Lumbar spine data analysis pitfalls: two examples of erroneous vertebral exclusion. ISCD suggest to exclude abnormal vertebrae from analysis when the T- score difference between the vertebra under evaluation and those adjacent is larger than one References: - Milan/IT Conclusion More than 90% of previous DXA presented at least one error, mainly due to data analysis. ISCD guidelines are very poorly adopted. Our study demonstrates that errors in DXA are frequent. Physicians should familiarize whit correct DXA interpretation practice to minimize these pitfalls. References 1. Kanis JA, McCloskey EV, Johansson H, Cooper C, Rizzoli R, Reginster JY; Scientific Advisory Board of the European Society for Clinical and Economic Aspects of Osteoporosis and Osteoarthritis (ESCEO) and the Committee of Scientific Advisors of the International Osteoporosis Foundation (IOF). European guidance for the diagnosis and management of osteoporosis in postmenopausal women. Osteoporos Int 2013;24(1):23-57 2. Kanis JA, Oden A, Johnell O, et al. The use of clinical risk factors enhances the performance of BMD in the prediction of hip and osteoporotic fractures in men and women. Osteoporos Int 2007;18(8):1033-1046 3. Schousboe JT, Shepherd JA, Bilezikian JP, Baim S. Executive summary of the 2013 International Society for Clinical Densitometry Position Development Conference on bone densitometry. J Clin Densitom 2013;16(4):455-466. 4. Watts NB. Fundamentals and pitfalls of bone densitometry using dual-energy X-ray absorptiometry (DXA). Osteoporos Int 2004;15(11):847-854. 5. Garg MK, Kharb S. Dual energy X-ray absorptiometry: Pitfalls in measurement and interpretation of bone mineral density. Indian J Endocrinol Metab 2013;17(2):203-210. Page 7 of 8
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