Performance Of Dual-energy X-ray Absorptiometry Research Articles

Bone health screening practices with dual-energy X-ray absorptiometry and prediction of abnormal results in pediatric inflammatory bowel disease.

Pediatric patients diagnosed with inflammatory bowel disease (IBD) are at risk of suboptimal peak bone mass attainment. This study aimed to understand rates of bone health screening adherence, describe factors associated with dual-energy X-ray absorptiometry (DXA) acquisition, and identify factors associated with abnormal DXA. We performed a retrospective cohort study of pediatric IBD patients over a 10-year time frame. We included IBD patients (2-20 years of age) enrolled in ImproveCareNow and excluded patients with primary metabolic bone disease. Time-to-event methods and multivariable logistic regression were employed to identify factors associated with DXA acquisition and abnormal DXA. In 676 patients, 464 (68.63%) pediatric patients with IBD had a risk factor for low bone mineral density (BMD); 137 (29.53%) underwent an initial DXA scan. Quiescent disease was significantly associated with a reduced likelihood of DXA (hazard ratio [HR]: 0.48; 95% confidence interval [CI]: 0.24-0.97), while weight z-score <-2 was significantly associated with DXA performance (HR: 2.07; 95% CI: 1.08-3.98). Abnormal DXA results (BMD z-score ≤-1) occurred in 59 (35.54%) individuals. After adjusting for visit diagnosis, delayed puberty, severe disease course, 6 months or greater of steroid exposure, and history of fracture, BMI z-score <-1 (odds ratio: 5.45; 95% CI: 2.41-12.33) was associated with abnormal DXA. DXA screening occurred in less than one-third of eligible pediatric IBD patients. Compliance was more common in patients with a weight z-score <-2 and less common in those with quiescent disease. BMI strongly predicted abnormal DXA results when adjusting for risk factors for abnormal BMD.

A Validated Risk Prediction Model for Bone Fragility in Children With Acute Lymphoblastic Leukemia.

Although bone fragility may already be present at diagnosis of pediatric acute lymphoblastic leukemia (ALL), routine performance of dual-energy X-ray absorptiometry (DXA) in every child is not universally feasible. The aim of this study was to develop and validate a risk prediction model for low lumbar spine bone mineral density (LS BMD Z-score ≤ -2.0) at diagnosis, as an important indicator for fracture risk and further treatment-related BMD aggravation. Children with ALL (4-18 years), treated according to the Dutch Childhood Oncology Group protocol (DCOG-ALL9; model development; n=249) and children from the Canadian Steroid-Associated Osteoporosis in the Pediatric Population cohort (STOPP; validation; n=99) were included in this study. Multivariable logistic regression analyses were used to develop the prediction model and to confirm the association of low LS BMD at diagnosis with symptomatic fractures during and shortly after cessation of ALL treatment. The area under the receiver operating characteristic curve (AUC) was used to assess model performance. The prediction model for low LS BMD at diagnosis using weight (β=-0.70) and age (β=-0.10) at diagnosis revealed an AUC of 0.71 (95% CI, 0.63-0.78) in DCOG-ALL9 and 0.74 (95% CI, 0.63-0.84) in STOPP, and resulted in correct identification of 71% of the patients with low LS BMD. We confirmed that low LS BMD at diagnosis is associated with LS BMD at treatment cessation (OR 5.9; 95% CI, 3.2-10.9) and with symptomatic fractures (OR 1.7; 95% CI, 1.3-2.4) that occurred between diagnosis and 12 months following treatment cessation. In meta-analysis, LS BMD at diagnosis (OR 1.6; 95% CI, 1.1-2.4) and the 6-month cumulative glucocorticoid dose (OR 1.9; 95% CI, 1.1-3.2) were associated with fractures that occurred in the first year of treatment. In summary, a prediction model for identifying pediatric ALL patients with low LS BMD at diagnosis, as an important indicator for bone fragility, was successfully developed and validated. This can facilitate identification of future bone fragility in individual pediatric ALL patients. © 2021 American Society for Bone and Mineral Research (ASBMR).

How to Interpret Dual Energy X-Ray Absorptiometry for Clinicians

Introduction: Dual energy X-ray absorptiometry (DXA) is a clinically proven method for measuring bone mineral density (BMD) in the lumbar spine, hip, femoral neck, and forearm. It is used for management and to monitor response of therapy of metabolic bone disease. Vertebral fracture assessment (VFA) is additional software that can be added to most DXA machines for the sole purpose of evaluating of occult fractures. DXA has excellent reproducibility, and emits low radiation dose (effective dose 1–3 mSv), which is equivalent to day-to-day background radiation. International Society for Clinical Densitometry (ISCD) recommends obtaining BMD of the posterolateral L1–L4, total hip, femoral neck, and distal one-third forearm.1 It is important for clinicians managing patients for metabolic bone disease to be able to review their own DXA images and reports to ensure the accuracy of the technical performance and interpretation. This is because DXA errors are not uncommon. One particular study of 354 DXA images reviewed showed 90% contained technical errors and 80% interpretation errors were found.2 ISCD has established guidelines for the best practice in DXA performance.3 Periodic quality assurance of DXA equipments should be performed by each center. Although most centers are knowledgeable, there still remains a gap in knowledge that affects interpretation. The aim of this video is to give a short review for clinicians on how to interpret BMD on their own and recognize pitfalls that can result in error in clinical decision making. Methods: A concise review of DXA images and reports is discussed. Results: A four-step approach on how clinicians can interpret their own DXA scan images is described in the video. The first step is to evaluate for proper positioning, review of edges placement, exclude artifacts such as lesions and calcifications if present, and confirm appropriate region-of-interest placement. By applying these four steps, clinicians can reduce potential errors that can lead to errors in medical management. In addition, clinical examples are given on how to monitor BMD changes overtime. This will require each institution to establish its margin of technical error known as precision error to determine its least significant change of each site (spine, total hip, femoral neck, and distal forearm). This allows clinicians to determine whether the change noted is clinically significant. The indications and interpretation of VFA are discussed.4 This is a lateral spine imaging to evaluate for fractures. This nicely augments DXA readings in those patients who are candidates for this VFA based on ISCD guidelines, which is discussed in this video. Conclusion: There are several quality measures needed to produce quality DXA images and reports. As clinicians, we should be empowered to be able to review our own DXA images and make appropriate clinical decisions regarding treatment. No competing financial interests exist. Runtime of video: 12 mins 52 secs

Body Composition, Serum Sclerostin and Physical Function After Bariatric Surgery: Performance of Dual-Energy X-ray Absorptiometry and Multifrequency Bioelectrical Impedance Analysis.

The aim of this study was to determine the effects of bariatric surgery and weight loss on body composition, serum sclerostin and physical performance. Seventy-three consecutive patients (36 non-surgical controls and 37 who underwent bariatric surgery) were evaluated by means of laboratory tests, multifrequency bioelectrical impedance analysis (BIA), total-body dual-energy X-ray absorptiometry (DXA), gait speed and handgrip strength. The differences between non-surgical and surgical patients were as follows: body mass index (BMI) 42.9 ± 5.7 vs 34.8 ± 6.0kg/m2 (p < 0.001); handgrip strength 31.3 ± 7.0 vs 27.1 ± 9.3kg (p < 0.033); skeletal muscle mass index (SMI)-BIA 12.3 ± 1.2 vs 10.6 ± 1.2kg/m2; fat-free mass index (FFMI)-BIA 21.9 ± 1.9 vs 18.9 ± 2.1k/m2 (p < 0.001 for all comparisons); Baumgartner-DXA 10.8 ± 1.5 vs 9.0 ± 1.4kg/m2 (p < 0.001); fat mass BIA 55.4 ± 12.5 vs 36.8 ± 9.6; fat mass DXA 54.3 ± 12.38 vs 35.1 ± 7.5kg (p < 0.001 for both comparisons) and serum sclerostin 30.9 ± 31.9 vs 26.9 ± 21.1pmol/L (p = 0.516). Positive correlation was found between BIA and DXA: SMI × Baumgartner (r = 0.842; p < 0.001) and fat mass (r = 0.970; p < 0.001). Gait speed was relatively preserved in sleeve gastrectomy (SG) compared with Roux-en-Y gastric bypass (RYGB) (1.2 ± 0.3 and 0.9 ± 0.1m/s; p = 0.038). Bariatric surgery leads to lower values of lean and fat mass and of handgrip strength with no differences in serum sclerostin concentrations. There was a positive correlation between BIA and DXA for fat and lean mass parameters. Physical performance was better after SG than in RYGB.

Effects of Traction on Interpretation of Lumbar Bone Mineral Density in Patients with Duchenne Muscular Dystrophy: A New Measurement Method and Diagnostic Criteria Based on Comparison of Dual-Energy X-Ray Absorptiometry and Quantitative Computed Tomography

Introduction: This study aimed to compare the performance of dual-energy X-ray absorptiometry (DXA) and quantitative computed tomography (QCT) in evaluating bone mineral density (BMD) of patients with Duchenne muscular dystrophy and scoliosis. Methodology: Twenty-nine participants (mean age 19.72 ± 6.13 years) underwent whole spine radiography, DXA before and after traction, and QCT alone without traction. Scoliosis and vertebral rotation angles obtained before and after traction were compared, and BMD values from DXA were compared to those obtained via QCT. The scoliosis angle, presented as Cobb's angle of L1–L4, was measured. Results: Cobb's angle significantly decreased from 30.38° ± 24.83° before traction to 22.78° ± 20.41° after traction (p < 0.0001) and the Z-score decreased from −1.88 ± 1.59 to −2.86 ± 2.16 (p < 0.0001). Changes in rotation angle, BMD, and bone mineral content were not significant. Post-traction BMD values and Z-scores showed a higher correlation with QCT measurements than pretraction. Moreover, pre and post-traction Z-scores (≤−1.1 and −1.36, respectively) were more accurate in identifying patients with osteoporosis according to QCT scans compared with the preexisting Z-score of −2 or less. Conclusion: Lumbar BMD measured via DXA and scoliosis allowed a more accurate diagnosis of osteoporosis when traction was applied.

Bone Mineral Densitometry (BMD) Precision and Scattered Radiation Level of Dual Energy X-ray Absorptiometry (DXA) Installed in Mymensingh Nuclear Medicine Unit, Bangladesh

Dual Energy X-ray Absorptiometry (DXA) has long been and remains the most widely used technique for Bone Mineral Densitometry (BMD) measurement. Several manufacturers developed their performance of DXA with various types of measurement software but still not a unique data processing system which can ensure the unique measurement for the patients. The aim of this article is to show the precision level of BMD in DXA machine GE (Model: DPX Lunar) installed at INMAS, Mymensingh and to measure background radiation consistency during acquisition. A rectangular shape QA phantom of variable density for precision measurement and survey meter (Austral Rad Mini 8 in 1) for radiation monitoring were used. Coefficient of Variation for BMD values was 0.37% and always ranges from 0.32% to 0.38%. Radiation survey meter reading always showed the values ranges from 0-3 µSv/hr. It can be concluded that these good QC are not the conformity of exact measurement because there some reference values involved in T-score or Z-score measurement. These reference values were taken from healthy adult Caucasian women which are different from Bangladeshi population.

DXA Performance in a Pediatric Population: Precision of Body Composition Measurements in Healthy Term-Born Infants Using Dual-Energy X-ray Absorptiometry

Dual-energy X-ray absorptiometry (DXA) has been hailed as a golden standard for measuring body composition in adults but remains to be fully assessed for the infant population. A total of 64 newborn infants were allocated to 1 of 3 groups. All underwent 2 Hologic Discovery A DXA scans. Suboptimal scans were reconstructed, and an investigation into the success of adjustment was carried out. Depending on group, the factors of weight change and repositioning were investigated. Test-retest variation and coefficients of variation for DXA body composition estimates were calculated. Furthermore, the effects of flannel sheets and breast milk were investigated using a pediatric phantom. Reconstruction of suboptimal scans resulted in more accurate body weight estimates. Moderate weight change and repositioning had no significant effect on the variation between scans. No significant body composition changes occurred between scans. The test-retest variation varied between 6.3% and 11.8%. Flannel sheets and breast milk affected DXA results significantly. High precision of DXA measurements was obtained in our newborn population. Reconstructing scans is a viable way of correcting minor movement artifacts. Moderate weight changes and repositioning have no significant effect on DXA results, whereas flannel sheets and milk do.

Bone Health in Children and Adolescents With Chronic Diseases That May Affect the Skeleton: The 2013 ISCD Pediatric Official Positions

The aim of this Task Force was to review the use of dual-energy X-ray absorptiometry (DXA) in children and adolescents with underlying chronic diseases that pose risk factors for compromised bone health, such as inflammation, glucocorticoid therapy, or decreased mobility. The Task Force systematically analyzed more than 270 studies, with an emphasis on those published in the interval since the original 2007 Position Statements. Important developments over this period included prospective cohort studies demonstrating that DXA measures of areal bone mineral density (aBMD) predicted incident fractures and the development of robust reference data and strategies to adjust for bone size in children with growth impairment. In this report, we summarize the current literature on the relationship between DXA-based aBMD and both fracture (vertebral and non-vertebral) outcomes and non-fracture risk factors (e.g., disease characteristics, ambulatory status, and glucocorticoid exposure) in children with chronic illnesses. Most publications described the aBMD profile of children with underlying diseases, as well as the cross-sectional or longitudinal relationship between aBMD and clinically relevant non-fracture outcomes. Studies that addressed the relationship between aBMD and prevalent or incident fractures in children with chronic illnesses are now emerging. In view of these updated data, this report provides guidelines for the use of DXA-based aBMD in this setting. The initial recommendation that DXA is part of a comprehensive skeletal healthy assessment in patients with increased risk of fracture is unchanged. Although the prior guidelines recommended DXA assessment in children with chronic diseases at the time of clinical presentation with ongoing monitoring, this revised Position Statement focuses on the performance of DXA when the patient may benefit from interventions to decrease their elevated risk of a clinically significant fracture and when the DXA results will influence that management.

Detection of Prefracture Hip Lesions in Atypical Subtrochanteric Fracture with Dual-Energy X-ray Absorptiometry Images

To retrospectively assess how often and how early hip dual-energy x-ray absorptiometry (DXA) images show prefracture lesions in patients with atypical subtrochanteric fracture (ASF) and determine whether DXA images with assessment of prodromal symptoms could be used for early ASF prediction. The retrospective research protocol complied with HIPAA and was institutional review board approved, with waiver of informed consent. Among 62 women with ASF, nine without hip DXA images and seven without clear documentation of prodromal symptoms were excluded. Serial DXA images of 52 hips in 46 patients were included. Among them, 33 hips were assessed with ipsilateral DXA. For this ipsilateral group, each hip was assessed for prodromal symptoms and focal cortical changes in the lateral subtrochanteric femur cortex at DXA. Overall and cumulative detection rates for prodromal symptoms, DXA, and DXA with prodromal symptoms were measured and compared with a general linear model for overall detection rate and Cox proportional hazard models for cumulative detection rate. Thirty-three representative ipsilateral images and 199 images from subjects without fractures were reviewed in random order for prefracture lesions by three musculoskeletal radiologists independently, and the performance of DXA in ASF prediction was assessed. Overall detection rates for DXA, prodromal symptoms, and DXA with prodromal symptoms were 61% (20 of 33), 42% (14 of 33), and 73% (24 of 33), respectively, in the ipsilateral group. Overall detection rate comparisons showed that DXA with prodromal symptoms was superior to prodromal symptoms alone (P = .0377). The cumulative detection rate curve for DXA with prodromal symptoms was also superior to that of prodromal symptoms alone (P = .0018). Sensitivity and specificity of DXA in ASF prediction ranged from 52% (17 of 33) to 58% (19 of 33) and 99% (197 of 199) to 100% (199 of 199), respectively. Assessment of hip DXA images combined with conventional assessment of prodromal symptoms enables detection of more ASFs earlier than assessment based on prodromal symptoms alone.

Screening for Osteoporosis: U.S. Preventive Services Task Force Recommendation Statement

Update of the 2002 U.S. Preventive Services Task Force (USPSTF) recommendation on screening for osteoporosis. The USPSTF evaluated evidence on the diagnostic accuracy of risk assessment instruments for osteoporosis and fractures, the performance of dual-energy x-ray absorptiometry and peripheral bone measurement tests in predicting fractures, the harms of screening for osteoporosis, and the benefits and harms of drug therapy for osteoporosis in women and men. The USPSTF recommends screening for osteoporosis in women aged 65 years or older and in younger women whose fracture risk is equal to or greater than that of a 65-year-old white woman who has no additional risk factors. (Grade B recommendation) The USPSTF concludes that the current evidence is insufficient to assess the balance of benefits and harms of screening for osteoporosis in men. (I statement).

Assessment of the individual fracture risk of the proximal femur by using statistical appearance models

Standard diagnostic techniques to quantify bone mineral density (BMD) include dual-energy x-ray absorptiometry (DXA) and quantitative computed tomography. However, BMD alone is not sufficient to predict the fracture risk for an individual patient. Therefore, the development of tools, which can assess the bone quality in order to predict individual biomechanics of a bone, would mean a significant improvement for the prevention of fragility fractures. In this study, a new approach to predict the fracture risk of proximal femora using a statistical appearance model will be presented. 100 CT data sets of human femur cadaver specimens are used to create statistical appearance models for the prediction of the individual fracture load (FL). Calculating these models offers the possibility to use information about the inner structure of the proximal femur, as well as geometric properties of the femoral bone for FL prediction. By applying principal component analysis, statistical models have been calculated in different regions of interest. For each of these models, the individual model parameters for each single data set were calculated and used as predictor variables in a multilinear regression model. By this means, the best working region of interest for the prediction of FL was identified. The accuracy of the FL prediction was evaluated by using a leave-one-out cross validation scheme. Performance of DXA in predicting FL was used as a standard of comparison. The results of the evaluative tests demonstrate that significantly better results for FL prediction can be achieved by using the proposed model-based approach (R = 0.91) than using DXA-BMD (R = 0.81) for the prediction of fracture load. The results of the evaluation show that the presented model-based approach is very promising and also comparable to studies that partly used higher image resolutions for bone quality assessment and fracture risk prediction.

Prediction models for evaluation of total-body bone mass with dual-energy X-ray absorptiometry among children and adolescents.

The performance of dual-energy x-ray absorptiometry (DXA) in identifying children with decreased bone mass is increasing, but there is no consensus regarding how to interpret the results. The World Health Organization diagnostic categories for normal, osteopenia, and osteoporosis, based on T scores, are not applicable to children and adolescents who have not yet reached peak bone mass. The pediatric reference standards provided by DXA manufacturers have been questioned. Bone mineral density determined with DXA is "areal" density (a 2-dimensional measurement of a 3-dimensional structure), and its misleading nature among growing and maturing children is well recognized. Few published pediatric reference values for bone mineral density measured with DXA include factors that are known to affect the results besides age and gender. Our objective was to develop an algorithm for the evaluation of bone mass among children that included known determinants of bone mass and of its measurement with DXA. Height, weight, pubertal status, and total-body bone mineral content, total-body bone area, and total-body bone mineral density measured with DXA were recorded for an ethnically diverse group of healthy pediatric subjects (n = 1218; age: 6-18 years). Prediction models for bone measurements were developed and validated with healthy pediatric subjects and then applied to children with medical disorders. There was a significant gender effect, as well as an interaction between gender and ethnicity. Separate models were developed for log total-body bone mineral content, log total-body bone area, and 1/total-body bone mineral density for girls and boys. The variability explained for each measurement increased from level 1, including age and ethnicity (76-86%), to level 2, including age, ethnicity, height, and weight (84-97%), and to level 3, including age, ethnicity, height, weight, and bone area (89-99%). Pubertal stage was an additional significant predictor of bone measurements but increased the explained variability by only 0.1% with height and weight in the models. The values predicted with each model were not different from measured values for the validation group but were different for patients with medical disorders, with different patterns according to the diagnoses. These models, including known determinants of bone mass and of bone measurements with DXA, provide an evaluation of pediatric bone mass that proceeds in steps from level 1 to level 3. The outcomes were different for patients at risk for compromised bone mass, compared with healthy children, with specific patterns for each medical disorder. We propose an algorithm for evaluation of bone measurements that follows levels 1 to 3. Our findings suggest that application of this algorithm to well-characterized groups of pediatric patients could identify disease-specific features of DXA results. We recommend this approach as a basis for consensus regarding the clinical evaluation of pediatric bone mass, and we suggest that it could lead to meaningful classification of pediatric bone disorders, investigation of pathophysiologic processes, and development of appropriate interventions.

The effect of room temperature on dual-energy X-ray absorptiometry.

There has been little published data on the effects of temperature on the performance of dual-energy X-ray absorptiometry (DXA) machines. We examined the effect of changes in ambient room temperature on the performance of three DXA scanners (DPXL, Expert-XL and Prodigy). The study involved repeat measurements of bone mineral density (BMD) using three different spine phantoms scanned at different ambient room temperatures, both before and after calibration procedures. The calibration or quality assurance (QA) scan calibrates the scanner, adjusting for the ambient room temperature at the time of calibration. There was a moderate correlation between change in temperature and change in BMD measured prior to recalibration for the Expert-XL ( r=0.58) during normal clinical scanning conditions. There was no observed change in phantom BMD with change in temperature measured using the DXPL or Prodigy. After temperature change, without repeat calibration measurements, there was a strong correlation between temperature change and change in BMD measured using the Expert-XL ( r=0.96, p<0.001). From the regression equation, a change of 2.5 degrees C could alter the calculated BMD result measured by the Expert-XL by 1.5%, which would significantly affect the precision of the DXA system. There was no significant correlation between temperature and BMD in the DXPL or Prodigy. The observed differences between the densitometers and the effect of temperature change are most likely due to the differing types of detector systems used. Operators must be made aware that solid state detectors of the sort used in the Expert-XL (charge-coupled devices, CCDs) are significantly affected by changes in ambient room temperature.

Precision and sensitivity of dual-energy X-ray absorptiometry in spinal osteoporosis

This study evaluated the performance of dual-energy x-ray absorptiometry (DEXA) with regard to (1) the correlation with dual-photon absorptiometry (DPA), (2) the ability to discriminate between normal and osteoporotic patients, and (3) long-term reproducibility. The bone mineral density (BMD) of the spine in 112 subjects, both normal and osteoporotic, was measured with DPA and DEXA (Lunar Corporation, Madison, Wisconsin) of the spine. The femur BMD of 22 cases was also measured with both machines. The results for the two techniques were highly correlated (r greater than 0.9, SEM = 0.02 to 0.04 g/cm2). BMD was measured using DEXA in 80 women (mean age = 61 years) with established spinal osteoporosis and 110 normal age-matched controls. The osteoporotic patients had significantly reduced spine and femur BMDs compared to the controls: -23% for L2-4 BMD (Z score = 2.6) and -13 to -20% for femur BMD (Z score = 1.1-1.3). L2-4 BMD had the best discriminative value, with an area under the ROC curve of 94%; the Ward's triangle BMD had an area of 84%. The precision error in vitro in a phantom over a 1-year period was 0.7%. The measured precision in vivo with young adults was approximately 1% (SD = 0.012 g/cm2) for L2-4 BMD and 1.7-2.3% (SD = 0.015-0.022 g/cm2) for femur over the 1 year period. The reproducibility was not as good for osteoporotic patients (SD = 0.017 g/cm2).