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Dual-energy x-ray absorptiometry has sustained a niche for measuring bone mineral density since its approval by the Food and Drug Administration for clinical use in 1988. The 1998 Bone Mass Measurements Act in solidified its validity compared to other diagnostic modalities. Dual-energy x-ray absorptiometry is comparatively inexpensive, with notably shorter scan times and lower radiation exposure compared to other imaging options. A long-standing international consensus exists regarding guidelines for interpreting dual-energy x-ray absorptiometry images. Specific patient populations are especially at risk of osteoporosis and should be screened according to guidelines. Early detection of osteoporosis through dual-energy x-ray absorptiometry imaging is crucial for halting disease progression and improving patient health through therapeutic interventions. Targeted exercises and physical therapy have proven to be especially effective in slowing and reversing osteoporosis. This activity reviews the indications and limitations of dual-energy x-ray absorptiometry and highlights the interprofessional team's role in treating patients with osteoporosis. Objectives: Identify the indications for dual-energy x-ray absorptiometry. Assess factors that may cause suboptimal dual-energy x-ray absorptiometry images. Evaluate the clinical significance of dual-energy x-ray absorptiometry. Collaborate with the interprofessional team to manage patients with osteoporosis and improve their outcomes by incorporating dual-energy X-ray absorptiometry results into treatment planning. Access free multiple choice questions on this topic.

Dual-energy x-ray absorptiometry (DEXA) has sustained a niche for measuring bone mineral density (BMD) since its approval by the Food and Drug Administration for clinical use in 1988. The 1998 Bone Mass Measurements Act solidified its validity in light of other diagnostic modalities such as chemical analysis, direct dissection and ashing, quantitative ultrasonography, and computed tomography or magnetic resonance imaging. DEXA is relatively inexpensive, with notably shorter scan times and lower radiation exposure compared to other imaging modalities, and there is a long-standing consensus regarding guidelines for interpreting DEXA images. This test is performed using a C-arm with the x-ray source below the supine patient emitting photons at 2 distinct energy levels specific for soft tissue and cortical bone. A collimator is situated between the patient and the x-ray source to minimize scatter. The attenuations from these low- and high-energy photon emissions are detected above the patient and are combined to create a planar image to assess bone mass per unit of area (g/cm²) to determine BMD. A T-score represents the number of standard deviations between the patient's mean BMD and the population mean compared to reference populations matched in gender and race. The Z-score indicates the number of standard deviations above or below the mean of age-matched controls. Volumetric BMD measurements can be obtained from computed tomography scans, including those obtained for unrelated reasons, raising the possibility of retrospective or opportunistic readings to detect asymptomatic osteoporosis. Volumetric BMD is measured in g/cm³ and correlates well with DEXA imaging and other measures of BMD.[1][2]

The collaboration of the interprofessional healthcare team is crucial to ensure the appropriate DEXA test is ordered and performed correctly. According to ACR Appropriateness Criteria Osteoporosis and Bone Mineral Density, there are specific cases in which QCT is considered superior to DEXA. These include: Extremes in body height, such as very large and very small patients Patients with extensive degenerative disease of the spine Severely obese patients (BMI >35 kg/m²) A clinical scenario that requires increased sensitivity to small changes in trabecular bone density (parathyroid hormone and glucocorticoid treatment monitoring) [3] Pitfalls in DEXA are common, and errors can be categorized as patient positioning, data analysis, artifacts, or demographics. Structural changes, such as osteophytes, calcifications, or fractures, are more common in the lumbar spine compared to in the proximal femur and potentially cause an artefactual component of BMD.[6] Patient positioning may have the consequences of missing important anatomical regions, or excessive internal or external rotation of the proximal femur may cause non-negligible changes in BMD values.[7] Artifacts such as bra components, surgical clips, navel rings, and vascular prostheses may alter the final BMD, resulting in overestimation if the metal is included in the region of interest or underestimation if it is outside the region of interest.[8] Errors in assigning demographics are significant because the T-score is correlated to reference populations in gender and race. Some of the pitfalls can be avoided; however, some are unavoidable and must be considered by the healthcare team.

The DEXA scan should be used as a decision-making tool for Allied Health Professionals, such as physical and occupational therapists.[9] The multi-component training consists of a combination of different exercises, such as aerobics, strengthening, progressive resistance, balancing, and dancing, aimed at increasing and preserving bone mass.[10] Several types of exercise are recommended for patients with osteoporosis to counter bone mass reduction.[11] Combining multiple types of exercise can significantly affect BMD at three sites—the femoral neck, greater trochanter, and especially the spine. A meta-analysis of postmenopausal women found that resistance training increased lumbar BMD, and adding low-moderate impact exercises such as jogging, walking, and stair climbing was even more effective in preserving BMD at both lumbar and femoral levels.[12][13] Another study involving older and middle-aged men showed that resistance training and load-bearing exercise improved bone mass density rather than just decreasing the loss. A suggested exercise frequency is 3 or more sessions between 30 and 60 minutes each for at least 10 months to show BMD improvement.[14]