Dual-energy X-ray Absorptiometry Studies Research Articles

Stable fixation of an ultra-short femoral neck-preserving hip prosthesis: a 5-year RSA, DXA, and clinical prospective outcome study of 48 patients.

We previously showed promising primary stability and preservation of bone stock with the ultra-short neck-loading hip implant in total hip arthroplasty (THA). The aim of this study was to evaluate clinical outcome, implant stability, and bone mineral density (BMD). 50 patients were treated with the ultra-short neck Primoris hip implant at baseline and 48 were available for evaluation at 5-year follow-up. 5 different patient-reported outcome measures (PROMs) including hip-specific scores, disease-specific and generic quality of life outcome measures, and an activity score were used. Furthermore, implant stability using radiostereometric analysis (RSA) and assessment of periprosthetic BMD using dual-energy X-ray absorptiometry (DXA) were applied. By 1-year follow-up, all PROMs showed improvements and remained high at 5-year follow-up. After initial distal translation (subsidence) and negative rotation around the z-axis (varus tilt) the implant showed stable fixation at 5-year follow-up with no further migration beyond 12 months. In the regions of interest (ROI) 3 and 4, BMD remained stable. In ROI 2, further bone loss of 12% was found at 5-year follow-up. Clinical outcome including PROMs was satisfying throughout the 5-year follow-up period. The hip implant remains stable with both bone preservation and loss 5 years after surgery.

Opportunistic CT-Based Hounsfield Units Strongly Correlate with Biomechanical CT Measurements in the Thoracolumbar Spine.

Retrospective cohort study. Hounsfield units (HUs) are known to correlate with clinical outcomes, but no study has evaluated how they correlate with biomechanical computed tomography (BCT) and dual-energy x-ray absorptiometry (DXA) measurements. Low bone mineral density (BMD) represents a major risk factor for fracture and poor outcomes following spine surgery. DXA can provide regional BMD measurements but has limitations. Opportunistic HUs provide targeted BMD estimates; however, they are not formally accepted for diagnosing osteoporosis in current guidelines. More recently, BCT analysis has emerged as a new modality endorsed by the International Society for Clinical Densitometry for assessing bone strength. Consecutive cases from 2017 to 2022 at a single institution were reviewed for patients who underwent BCT in the thoracolumbar spine. BCT-measured vertebral strength, trabecular BMD, and the corresponding American College of Radiology Classification were recorded. DXA studies within three months of the BCT were reviewed. Pearson Correlation Coefficients were calculated, and receiver-operating characteristic curves were constructed to assess the predictive capacity of HUs. Threshold analysis was performed to identify optimal HU values for identifying osteoporosis and low BMD. Correlation analysis of 114 cases revealed a strong relationship between HUs and BCT vertebral strength ( r =0.69; P <0.0001; R2 =0.47) and trabecular BMD ( r =0.76; P <0.0001; R2 =0.58). However, DXA poorly correlated with opportunistic HUs and BCT measurements. HUs accurately predicted osteoporosis and low BMD (Osteoporosis: C =0.95, 95% CI 0.89-1.00; Low BMD: C =0.87, 95% CI 0.79-0.96). Threshold analysis revealed that 106 and 122 HUs represent optimal thresholds for detecting osteoporosis and low BMD. Opportunistic HUs strongly correlated with BCT-based measures, while neither correlated strongly with DXA-based BMD measures in the thoracolumbar spine. HUs are easy to perform at no additional cost and provide accurate BMD estimates at noninstrumented vertebral levels across all American College of Radiology-designated BMD categories.

Reference Value of Dual X-Ray Absorptiometry-Derived Lumbar Spine Trabecular Bone Score in the Thai Population

Introduction: Little is known about the normative values of trabecular bone score (TBS) in Thailand. We aimed to provide reference values of dual-energy x-ray absorptiometry (DXA)-derived lumbar spine TBS in Thai community-dwelling adults of varying ages. Methodology: Bone density studies of participants aged 20–90 years who underwent bone mineral density (BMD) testing at Srinagarind Hospital, Kohn Kaen, Thailand were reviewed. DXA studies were performed using a narrow fan-beam bone densitometer. Lumbar spine TBS for each of the L1–L4 vertebra was obtained using the iNsight software. Mean TBS (L1–L4 TBS) was calculated. This study was approved by the institutional research ethics committee (HE581241). Results: A total of 1372 participants were included. The mean ± SD age was 57.25 ± 17.35 years and 799 (58.2%) were female. There were 476 (34.7%) and 243 (17.7%) participants with osteopenia (T-score -1.0 to -2.5) and osteoporosis (T-score ≤-2.5) of the lumbar spine. Age and sex stratified analysis of L1–L4 TBS revealed peak TBS among females aged 30–49 years (mean ± SD: 1.42 ± 0.08) and males aged 30–59 years (mean ± SD: 1.42 ± 0.09). The rate of L1–L4 TBS reduction from ages 30 to 90 year is 13.4% (0.27%/year) for females and 5.6% (0.11%/year) for males. Conclusion: This is the first study reporting a normative database for DXA derived TBS in Thai community-dwelling population. We found that TBS decreased with age at the rate of approximately 0.27%/year for females and 0.11%/year for males.

Bone Response to Weight Loss Following Bariatric Surgery

Obesity is a global health challenge that warrants effective treatments to avoid its multiple comorbidities. Bariatric surgery, a cornerstone treatment to control bodyweight excess and relieve the health-related burdens of obesity, can promote accelerated bone loss and affect skeletal strength, particularly after malabsorptive and mixed surgical procedures, and probably after restrictive surgeries. The increase in bone resorption markers occurs early and persist for up to 12 months or longer after bariatric surgery, while bone formation markers increase but to a lesser extent, suggesting a potential uncoupling process between resorption and formation. The skeletal response to bariatric surgery, as investigated by dual-energy X-ray absorptiometry (DXA), has shown significant loss in bone mineral density (BMD) at the hip with less consistent results for the lumbar spine. Supporting DXA studies, analyses by high-resolution peripheral quantitative computed tomography (HR-pQCT) showed lower cortical density and thickness, higher cortical porosity, and lower trabecular density and number for up to 5 years after bariatric surgery. These alterations translate into an increased risk of fall injury, which contributes to increase the fracture risk in patients who have been subjected to bariatric surgery procedures. As bone deterioration continues for years following bariatric surgery, the fracture risk does not seem to be dependent on acute weight loss but, rather, is a chronic condition with an increasing impact over time. Among the post-bariatric surgery mechanisms that have been claimed to act globally on bone health, there is evidence that micro- and macro-nutrient malabsorptive factors, mechanical unloading and changes in molecules partaking in the crosstalk between adipose tissue, bone and muscle may play a determining role. Given these circumstances, it is conceivable that bone health should be adequately investigated in candidates to bariatric surgery through bone-specific work-up and dedicated postsurgical follow-up. Specific protocols of nutrients supplementation, motor activity, structured rehabilitative programs and, when needed, targeted therapeutic strategies should be deemed as an integral part of post-bariatric surgery clinical support.

Bone Health in Pediatric Fracture Patients: A DEXA Study

Vitamin D deficiency is widespread in children and is associated with increased fracture severity. Previous studies have shown mixed results on the impact of vitamin D supplementation on bone health parameters measured on dual-energy x-ray absorptiometry (DEXA) scan. This is the first longitudinal DEXA study in a pediatric fracture population. Pediatric fracture patients with vitamin D levels below 20 ng/mL were counseled to take vitamin D and calcium per a serum-based protocol. Patients underwent baseline DEXA within the initial 12 weeks post fracture and had follow-up scans at 6 and 12 months. 48 patients were enrolled, 32 patients completed two DEXA scans, and 19 completed three DEXA scans. There was a significant increase in lumbar spine BMC, TBLH BMD, and TBLH BMC between DEXA 1 and 2 (p 0.001). A positive trend in DEXA parameters is suggested between DEXA 1 and DEXA 3. Height adjusted z-scores (HAZ) were calculated which showed no statistical significance, p-values > 0.05. In this group, there are no significant changes in TBLH, BMC or BMD z-scores one year after fracturing despite vitamin D and calcium supplementation. This suggests that children returning to collision sports may be at continued risk for refracture and future studies are needed.

Imaging-based body fat depots and new-onset atrial fibrillation in general population

Abstract Background Obesity is a well-established risk factor for incident atrial fibrillation (AF). Whether different body fat depots differentially associate with AF development remains largely unknown. Purpose We aimed to investigate the associations between various body fat depots and the risk of new-onset AF among middle-aged and elderly individuals from general population. Methods In the prospective population-based cohort study, body composition was assessed using dual-energy X-ray absorptiometry (DXA) and total body mass, lean mass, fat mass, android and gynoid fat were analyzed (N=3468). Liver fat and epicardial fat were assessed using computed tomography (CT) (N=2145). A body fat score was defined by adding tertiles of each fat depot. All participants were followed for the occurrence of AF until 1st Jan. 2014. Principle component analysis was conducted to identify body fat distribution patterns. Time-to-event analyses were performed using Cox proportional hazards regression analysis. Hazard ratios (HR) and 95% confidence-intervals (95% CI), adjusted for cardiovascular risk factors, were calculated. Results Mean (standard deviation) of age for participants in DXA study and CT study was 74.42 (6.85) and 68.66 (6.41) years, respectively. AF incidence rate was 13.1 per 1000 person-years during a median follow-up time of 9.62 years. In the adjusted model, fat mass (HR; 95% CI: 1.33; 1.05–1.68), lean mass (1.40; 1.15–1.72), gynoid fat mass (1.36; 1.12–1.65), and total body mass (1.51; 1.21–1.89) were significantly associated with new-onset AF. Of note, android-to-gynoid fat ratio was inversely associated with incident AF (HR; 95% CI: 0.81; 0.70–0.94). Larger body fat score was associated with increased risk of incident AF (P for trend &amp;lt;0.01). Two fat distribution patterns were identified. Adherence to the fat- and gynoid fat- pattern (P for trend = 0.035), but not muscle- and visceral fat- pattern (P for trend = 0.35), was significantly associated with larger risk of new-onset AF. Conclusions Various body fat depots were associated with new-onset AF. Larger values of total body mass carried the highest risk for incident AF. The inverse association between android to gynoid fat ratio with AF presents a novel finding. A significant dose-response relationship between body fat accumulation and risk of new-onset AF was observed, implying a collective impact of fat depots on AF development. Findings also suggest that various fat depots, characterized by different fat distribution patterns, may exert differential combined effect on the risk of incident AF. Funding Acknowledgement Type of funding sources: None. Fat depots and atrial fibrillation

DXA Versus Clinical Measures of Adiposity as Predictors of Cardiometabolic Diseases and All-Cause Mortality in Postmenopausal Women

ObjectiveTo investigate whether dual-energy x-ray absorptiometry (DXA) estimates of adiposity improve risk prediction for cardiometabolic diseases over traditional surrogates, body mass index (BMI), waist circumference (WC), and waist-to-hip ratio (WHR) in older women. Patients and MethodsWe analyzed up to 9744 postmenopausal women aged 50 to 79 years participating in the Women’s Health Initiative who underwent a DXA scan and were free of cardiovascular disease and diabetes at baseline (October 1993 to December 1998) and followed through September 2015. Baseline BMI, WC, WHR, and DXA-derived percent total-body and trunk fat (%TrF) were incorporated into multivariable Cox proportional hazards models to estimate the risk of incident diabetes, atherosclerosis-related cardiovascular diseases (ASCVDs), heart failure, and death. Concordance probability estimates assessed the relative discriminatory value between pairs of adiposity measures. ResultsA total of 1327 diabetes cases, 1266 atherosclerotic cardiovascular disease (ASCVD) cases, 292 heart failure cases, and 1811 deaths from any cause accrued during a median follow-up of up to 17.2 years. The largest hazard ratio observed per 1 standard deviation increase of an adiposity measure was for %TrF and diabetes (1.77; 95% CI, 1.66-1.88) followed by %TrF and broadly defined ASCVD (1.22; 95% CI, 1.15-1.30). These hazard ratios remained significant for both diabetes (1.47; 95% CI, 1.37-1.57) and ASCVD (1.22; 95% CI, 1.14-1.31) even after adjusting for the best traditional surrogate measure of adiposity, WC. Percentage of trunk fat was also the only adiposity measure to demonstrate statistically significant improved concordance probability estimates over BMI, WC, and WHR for diabetes and ASCVD (all P<0.05). ConclusionDXA-derived estimates of abdominal adiposity in postmenopausal women may allow for substantially improved risk prediction of diabetes over standard clinical risk models. Larger DXA studies with complete lipid biomarker profiles and clinical trials are needed before firm conclusions can be made.

Bone Health Outcomes at 1 Year after Hematopoietic Stem Cell Transplantation in a Heterogeneous Pediatric Population

Impaired bone mineral density (BMD) is a known complication of hematopoietic stem cell transplantation (HSCT) in adults and may lead to increased fracture risk. Less is known in children about the risks for impaired BMD and fragility (low trauma) fractures after HSCT. In this study, we evaluated the incidence of fragility fractures in a large diverse pediatric HSCT recipient population and identified risk factors for both fracture and impaired BMD. We reviewed the records of 237 patients age ≤21 years at the time of transplantation who underwent HSCT at our institution between January 2015 and March 2018. The primary endpoint was the incidence of fragility fractures, and the secondary endpoint was assessment of BMD on dual-energy X-ray absorptiometry (DXA). DXA studies were available for analysis in 79 of 206 patients who were alive at 1 year after HSCT, and the median height-for-age adjusted z-score for spine BMD was 0.15. Among the 237 patients in this study, 25 (10.5%) had evidence of at least 1 fragility fracture on imaging. In the patients with at least 1 fragility fracture, 18 (72%) sustained spine fractures. The median time to fracture was 5.9 months after HSCT. Mortality at 1 year was proportionally higher, although not statistically significantly so (P=.11) in patients who had at least 1 fragility fracture (24%; 6 of 25) compared with patients without a fragility fracture (12%; 25 of 212). Vitamin D status at 1 year post-HSCT was sufficient (>20 ng/mL) in 94% of the patients assessed (160 of 171). There was no difference in the incidence of fracture between vitamin D-sufficient patients and vitamin D-insufficient patients (P=1.0). The incidence of fracture was significantly higher in patients with graft-versus-host disease (GVHD) compared with those without GVHD (15% vs 6%; P=.02). There was no significant difference in fracture occurrence between patients who received reduced-intensity conditioning and those who received myeloablative conditioning. The cumulative glucocorticoid dose was significantly associated with fracture in patients exposed to glucocorticoids for >3 months (P=.03). The incidence of fragility fractures, especially vertebral compression fractures, after pediatric HSCT is striking. Furthermore, there may have been additional, asymptomatic patients in our cohort with undetected, occult fractures. The high incidence of fragility fractures seen in this study advocates for establishing bone health screening protocols with attention to spinal imaging in pediatric patients undergoing HSCT.

Correlation between Hounsfield unit derived from head, thorax, abdomen, spine and pelvis CT and t-scores from DXA.

CT examination can potentially be utilised for early detection of bone density changes with no additional procedure and radiation dose. We hypothesise that the Hounsfield unit (HU) measured from CT images is correlated to the t-scores derived from dual energy X-ray absorptiometry (DXA) in multiple anatomic regions. Data were obtained retrospectively from all patients who underwent both CT examinations - brain (frontal bone), thorax (T7), abdomen (L3), spine (T7 & L3) or pelvis (left hip) - and DXA between 2014 and 2018 in our centre. To ensure comparability, the period between CT and DXA studies must not exceed one year. Correlations between HU values and t-scores were calculated using Pearson's correlation. Receiver operating characteristic (ROC) curves were generated, and the area under the curve (AUC) was used to determine threshold HU values for predicting osteoporosis. The inclusion criteria were met by 1043 CT examinations (136 head, 537 thorax, 159 lumbar and 151 left hip). The left hip consistently provided the most robust correlations (r = 0.664-0.708, p < 0.001) and the best AUC (0.875-0.893). Meanwhile, thorax T7 and lumbar L3 showed average correlations (range of r values is 0.497-0.679, p < 0.001, AUC range = 0.680-0.783, 95% CI 0.561-0.922, all p < 0.02) and moderate AUC (0.680-0.783). Frontal bone shows low correlation and weak AUC with r < 0.5, AUC = 0.538-0.655, all p > 0.05. HU values derived from the hip, T7 and L3 provided a good to moderate correlation to t-scores with a good prediction for osteoporosis. The suggested optimal thresholds may be used in clinical settings after external validations are performed.

A cemented mobile-bearing total knee prosthesis prevents peri-prosthetic bone mineral density loss around the femoral component: a consecutive follow-up at a mean of 11years.

Research has shown that a cemented mobile-bearing component has a favorable effect on the bone mineral density (BMD) of the distal femur at 2years after total knee arthroplasty (TKA). This study was performed to determine whether the advantage on BMD of a cemented mobile-bearing TKA over a conventional cemented fixed-bearing TKA changes with time. This report is an update of a matched cohort study initiated in 2004 and for which the 2-year results have been published. Twenty-eight knees that were treated with a fixed-bearing posterior stabilized (PS) prosthesis and 28 matched knees from a database of 76 knees that were treated with a mobile-bearing PS prosthesis in the same period were investigated. All knees underwent dual-energy X-ray absorptiometry (DEXA) scans around the femoral component preoperatively, 2weeks postoperatively, 5years postoperatively, and annually thereafter. Eighteen knees with a cemented mobile-bearing PS prosthesis and 20 knees with a cemented fixed-bearing PS prosthesis were investigated for more than 6years. The mean follow-up period was 11years. The range of motion, Knee Society Score, BMD of the lumbar spine, and follow-up period were not significantly different preoperatively and postoperatively in the two groups. In the fixed-bearing group, the BMD of the anterior part of the femoral condyle decreased postoperatively. In the mobile-bearing group, the BMD of the posterior part of the femoral condyle increased postoperatively. The postoperative change in the BMD at 5years and the latest follow-up period was statistically significant in the two groups. This DEXA study revealed that a cemented mobile-bearing component had a favorable effect on the BMD of the distal femur after TKA even at a mean of 11years postoperatively. Therapeutic study, level II, prospective comparative study.

Comparison of Radiographic Singh Index with Dual-Energy X-Ray Absorptiometry Scan in Diagnosing Osteoporosis

Objective: The objective of this study was to assess the accuracy of radiographic Singh index (SI) with respect to dual-energy X-ray absorptiometry (DEXA) scan in diagnosing osteoporosis. Materials and Methods: We conducted a cross-sectional study on 100 postmenopausal women in the Department of Radiodiagnosis, SKIMS, Soura, Srinagar, from June 2019 to December 2019. We obtained right or left standard anteroposterior hip radiograph in each patient and compared its SI grade to the densitometry results obtained from the DEXA study of the corresponding hip. Results: Out of the selected patients, 7% had DEXA bone mineral density (BMD) values in normal range (T-score ≤1), 81% in osteopenic range (T-score >1.00–<2.5), and 12% in osteoporotic range (T-score ≥2.5). There was no statistically significant correlation (r = −0.108, P = 0.286) between SI grade and WHO BMD category (normal, osteopenia, or osteoporosis). There was no statistically significant correlation (r = 0.191, P = 0.057) between the SI grade and the mean absolute DEXA BMD value. There was also no statistically significant correlation (r = −0.195, P = 0.052) between SI grade and mean DEXA T-score. Conclusion: Our study found a poor correlation between radiographic SI and DEXA densitometry results. We concluded that the SI cannot be used as a substitute for DEXA study in diagnosing osteoporosis.

Bone Mineral Densitometry Reporting: Pearls and Pitfalls

Dual-energy X-ray absorptiometry (DXA) is the method of choice for assessing bone mineral density (BMD). Unfortunately, the performance and interpretation of DXA can be challenging and errors are common. In fact, it has been reported that up to 90% of BMD reports contain at least 1 error. Errors can be the result of technique or interpretative in nature or both and can result in inappropriate diagnosis and management. In this article, we review the various types of pitfalls frequently encountered by physicians interpreting DXA studies. Being aware of these pitfalls will help readers recognize and avoid them when encountered in clinical practice.

Utilizing Artificial Intelligence to Determine Bone Mineral Density Via Chest Computed Tomography.

The purpose of this study was to validate the accuracy of an artificial intelligence (AI) prototype application in determining bone mineral density (BMD) from chest computed tomography (CT), as compared with dual-energy x-ray absorptiometry (DEXA). In this Institutional Review Board-approved study, we analyzed the data of 65 patients (57 female, mean age: 67.4 y) who underwent both DEXA and chest CT (mean time between scans: 1.31 y). From the DEXA studies, T-scores for L1-L4 (lumbar vertebrae 1 to 4) were recorded. Patients were then divided on the basis of their T-scores into normal control, osteopenic, or osteoporotic groups. An AI algorithm based on wavelet features, AdaBoost, and local geometry constraints independently localized thoracic vertebrae from chest CT studies and automatically computed average Hounsfield Unit (HU) values with kVp-dependent spectral correction. The Pearson correlation evaluated the correlation between the T-scores and HU values. Mann-Whitney U test was implemented to compare the HU values of normal control versus osteoporotic patients. Overall, the DEXA-determined T-scores and AI-derived HU values showed a moderate correlation (r=0.55; P<0.001). This 65-patient population was divided into 3 subgroups on the basis of their T-scores. The mean T-scores for the 3 subgroups (normal control, osteopenic, osteoporotic) were 0.77±1.50, -1.51±0.04, and -3.26±0.59, respectively. The mean DEXA-determined L1-L4 BMD measures were 1.13±0.16, 0.88±0.06, and 0.68±0.06 g/cm, respectively. The mean AI-derived attenuation values were 145±42.5, 136±31.82, and 103±16.28 HU, respectively. Using these AI-derived HU values, a significant difference was found between the normal control patients and osteoporotic group (P=0.045). Our results show that this AI prototype can successfully determine BMD in moderate correlation with DEXA. Combined with other AI algorithms directed at evaluating cardiac and lung diseases, this prototype may contribute to future comprehensive preventative care based on a single chest CT.

DEXA sensitivity analysis in patients with adult spinal deformity

BACKGROUNDAdult spinal deformity (ASD) is a debilitating condition that commonly requires surgical intervention. However, ASD patients may also present with osteoporosis, predisposing them to surgical complications and failure of instrumentation. As a result, proper detection of low bone mineral density (BMD) is critical in order to ensure proper patient care. Typically dual-energy x-ray absorptiometry (DEXA) scans are performed on the hip and spine. Unfortunately, in ASD patients, the latter is often inaccurate PURPOSEIn this study, we consider the value of obtaining a forearm DEXA scan in addition to a hip scan in patients suffering from ASD and osteoporosis in order to accurately detect low BMD. STUDY DESIGNRetrospective study. PATIENT SAMPLEPatient data between 2016 and 2018 from a single academic medical center was utilized. Two hundred eighty-six patients met the initial search criteria. OUTCOME MEASURESNo outcomes measures related to self-reporting, physiology, or functionality were evaluated in this study. Primary outcome measures analyzed included T-scores across various anatomic locations and diagnoses relating to low bone density (ie, osteopenia and osteoporosis). METHODSThis retrospective study examines patients that underwent DEXA studies between 2016 and 2018 and were previously diagnosed with both osteoporosis and adult spinal deformity. For each patient, age, gender, body mass index, and smoking history were noted, as well as whether there was long-term prednisone use. T-scores from both the forearm and hip were recorded and analyzed. Diagnoses from hip DEXA scans were compared with those obtained from forearm scans to identify which region was more sensitive in detecting low BMD. From this data, the frequency of a missed diagnosis, due to reliance on hip or spine T-scores for detection of low BMD, was extrapolated. No external funding source was received in support of this study. RESULTSTwo hundred eighty-six patients matched the initial search criteria. Only 68% had one T-score value. However, 24.8% of patients had data for both the hip and forearm, whereas 7.1% had data for the forearm, hip, and spine. Among the 85 patients with more than one anatomical site of study, the forearm was more sensitive than the hip in its ability to detect osteopenia or osteoporosis 41.2% of the time. A two-tailed t test showed no statistically significant difference between hip T-scores and forearm T-scores. However, for more than 17% of patients, the forearm allowed clinicians to detect osteoporosis or osteopenia in a setting where using only the hip data would have missed such a diagnosis. CONCLUSIONSClinicians need to ensure they survey at least two locations when conducting DEXA studies before precluding a diagnosis of osteopenia or osteoporosis. All ASD patients being evaluated for low bone density should receive DEXA scans that survey at least the hip and the forearm. Misdiagnoses can be costly in the setting of ASD. They occur frequently when only a single hip scan is relied upon to assess BMD.

Computer-Aided Detection of Incidental Lumbar Spine Fractures from Routine Dual-Energy X-Ray Absorptiometry (DEXA) Studies Using a Support Vector Machine (SVM) Classifier.

To assess whether application of a support vector machine learning algorithm to ancillary data obtained from posterior-anterior dual-energy X-ray absorptiometry (DEXA) studies could identify patients with lumbar spine (L1-L4) vertebral body fractures without additional DEXA imaging or radiation. Three hundred seven patients (199 without any fractures of the spine, and 108 patients with at least one fracture of the L1, L2, L3, or L4 vertebral bodies) who had DEXA studies were evaluated. Ancillary data from DEXA output was analyzed. The dataset was split into training (80%) and test (20%) datasets. Support vector machines (SVMs) with 10-fold cross-validation and different kernels were used to identify the best kernel based on the greatest area under the curve (AUC) and the best training vectors in the training dataset. The SVM with the best kernel was then applied to the test dataset to assess the accuracy of the SVM. Receiver operating characteristic (ROC) curves of the SVMs using different kernels in the test dataset were compared using DeLong's test. The SVM classifier with the linear kernel had the greatest AUC in the training dataset (AUC = 0.9258). The AUC of the SVM classifier with the linear kernel in the test dataset was 0.8963. The SVM classifier with the linear kernel had an overall average accuracy of 91.8% in the test dataset. The sensitivity, specificity, positive predictive value, and negative predictive of the SVM classifier with the linear kernel to detect lumbar spine fractures were 81.8%, 97.4%, 94.7%, and 90.5%, respectively. The SVM classifier with the linear kernel ROC curve had a significantly better AUC than the SVM classifier with the cubic polynomial kernel (P = 0.034) for discriminating between patients with lumbar spine fractures and control patients, but not significantly different from the SVM classifier with a radial basis function (RBF) kernel (P = 0.317) or the SVM classifier with a sigmoid kernel (P = 0.729). All fractures identified by the SVM classifiers were not prospectively identified by the radiologist. SVM analysis of ancillary data obtained from routine DEXA studies can identify lumbar spine fractures without the use of vertebral fracture assessment (VFA) DEXA imaging or radiation, and identify fractures missed by radiologists.

Random forest classifiers aid in the detection of incidental osteoblastic osseous metastases in DEXA studies

Dual-energy X-ray absorptiometry (DEXA) studies are used for screening patients for low bone mineral density (BMD). Patients with breast and prostate cancer are often treated with hormone-altering drugs that result in low BMD. These patients may have incidental osteoblastic metastases of the spine that may be detected on screening DEXA studies. The aim of this pilot study is to assess whether random forest classifiers or support vector machines can identify patients with incidental osteoblastic metastases of the spine from screening DEXA studies and to evaluate which technique is better. We retrospectively reviewed the DEXA studies from 200 patients (155 normal control patients and 45 patients with osteoblastic metastases of one or more lumbar vertebral bodies from L1 to L4). The dataset was split into training (80%) and validation (20%) datasets. The optimal random forest (RF) and support vector machine (SVM) classifiers were obtained. Receiver-operator-characteristic curves were compared with DeLong's test. The sensitivity, specificity, accuracy and area under the curve (AUC) of the optimal RF classifier were 77.8%, 100.0%, 98.0% and 0.889, respectively, in the validation dataset. The sensitivity, specificity, accuracy and AUC of the optimal SVM classifier were 33.3%, 96.8%, 82.5% and 0.651 in the validation dataset. The RF classifier was significantly better than the SVM classifier (P = 0.008). Only 7 of the 45 patients with osteoblastic metastases (15.6%) were prospectively identified by the radiologist interpreting the study. RF classifiers can be used as a useful adjunct to identify incidental lumbar spine osteoblastic metastases in screening DEXA studies.

Investigating a relationship between body composition and spinal curvature in farmed adult New Zealand king salmon (Oncorhynchus tshawytscha): A novel application of dual-energy X-ray absorptiometry

Characterising the pathology of skeletal anomalies in farmed finfish is key to elucidating the underlying causes. Spinal curvature is frequently observed in farmed New Zealand king salmon (Oncorhynchus tshawytscha), but its cause is currently unknown and knowledge about its pathology is limited. Dual-energy X-ray absorptiometry (DXA) was used to investigate the relationship between spinal curvature and body composition in farmed adult New Zealand king salmon. Differences in fat mass (FM), lean mass (LM) and bone mineral content (BMC) between harvest-sized fish affected and unaffected by spinal curvature were evaluated. As there is presently no evidence of an association between spinal curvature and vertebral mineral loss, between-group differences in BMC were not anticipated. Conversely, as spinal anomalies can alter the swimming and feeding of affected fish, and existing research suggests a role for soft tissues in spinal curvature development, differences in FM and LM were expected. Whole-body and regional (cranial, trunco-cranial, trunco-caudal and caudal spine) measurements of percent FM, LM and BMC were obtained from lateral DXA scans of size-matched adult female king salmon (1890–6903 g) affected (n = 31) and unaffected (n = 31) by spinal curvature. Repeatability was comparable to previous DXA studies. Measurements of FM and LM by DXA and chemical carcass analysis (CCA) were highly similar. As frequently reported in previous animal-based studies, DXA-derived BMC values were significantly lower than those obtained from CCA. Contrary to the overarching hypothesis, there were no significant between-group differences in whole-body or regional FM, LM or BMC, suggesting that there was no relationship between body composition and spinal curvature. Though the relationship between soft tissue changes and spinal curvature remains to be determined, DXA appears to be a viable tool for non-invasive assessment of king salmon body composition. However, studying end-stage disease has recognised limitations, so future investigations should utilise longitudinal designs.

Automated Reporting of DXA Studies Using a Custom-Built Computer Program.

Dual-energy x-ray absorptiometry (DXA) scans are a critical population health tool and relatively simple to interpret but can be time consuming to report, often requiring manual transfer of bone mineral density and associated statistics into commercially available dictation systems. We describe here a custom-built computer program for automated reporting of DXA scans using Pydicom, an open-source package built in the Python computer language, and regular expressions to mine DICOM tags for patient information and bone mineral density statistics. This program, easy to emulate by any novice computer programmer, has doubled our efficiency at reporting DXA scans and has eliminated dictation errors.

Adherence to Osteoporosis Screening and Its Related Factors: A Population-Based Study, Kerman, Iran

Background: Adherence to screening services is a prerequisite for the success of screening programs. Objectives: This study aimed at determining factors associated with participants’ compliance with Dual-energy X-ray Absorptiometry (DXA) screening for osteoporosis. Methods: In this population-based participatory study, 1000 males and females older than 55 years old were invited to participate in the study. The study took place in the city of Kerman, Iran, where subjects were informed face to face about the risk factors and complications of osteoporosis and asked to complete a questionnaire. The subjects were then invited to visit a densitometry center for a free DXA study. Four rural areas and 4 locations in Kerman were selected based on municipal divisions. Results: A total of 923 individuals completed the questionnaire: 562 (60.9%) were female, nearly two-thirds were from urban areas, and 284 (30.8%) were willing to undergo densitometry. Eight percent had a history of corticosteroid use for more than 3 months. About two-thirds of the participants were walking less than 150 minutes per week. In the logistic regression analysis, urban residents (OR = 1.88), females (OR = 1.52), and those who perceived high risk of osteoporosis (OR = 1.67) were more likely to adhere to DXA screening. Conclusions: On the whole, despite informing people about osteoporosis and offering free services, compliance to densitometry was not remarkable.

Impaired Bone Mineral Density in Pediatric Patients with Chronic Graft-versus-Host Disease

Pediatric allogeneic hematopoietic stem cell transplantation (AHSCT) recipients with chronic graft-versus-host disease (cGVHD) are at high risk for endocrinopathies, particularly impaired bone mineral density (BMD). However, rates of BMD impairment in pediatric AHSCT recipients with cGVHD have not been well documented. We report 33 patients with cGVHD who were referred to the National Institutes of Health (NIH) for the Natural History of Clinical and Biological Factors Determining Outcomes in Chronic Graft-versus-Host Disease Study (NCT 0092235) and underwent formal BMD assessment via dual-energy X-ray absorptiometry (DEXA). Not surprisingly, we found much higher rates of BMD impairment than previously reported for pediatric AHSCT recipients who were not stratified by the presence or absence of cGVHD. Most of these patients (73%) had a z-score ≤−2 in at least 1 anatomic site. Although we expected the rate to be higher than that observed for pediatric AHSCT recipients in studies that did not analyze patients with cGVHD separately, this rate is nonetheless extremely high. Furthermore, the overall rate of occult vertebral compression fractures (VCFs) in our cohort was 17%, and the rate was 23% in patients with at least 1 z-score of ≤−2. The rates of BMD impairment and VCF in our pediatric cohort were significantly higher than those seen in the adult AHSCT recipients who were concurrently enrolled on the same study at the NIH and had similar cGVHD severity. We found that older age at cGVHD diagnosis and a greater number of systemic therapies were associated with occult VCF. Moreover, the intensity of current immunosuppression negatively impacted lumbar spine and total hip BMD in this cohort. Our study, although limited by small patient numbers and lack of a control AHSCT recipient group without cGVHD, indicates that children with cGVHD are at a greater risk for BMD impairment than previously appreciated. Given the rising incidence of cGVHD in AHSCT recipients and our findings, we recommend that pre-AHSCT DEXA be incorporated into routine pediatric pretransplantation screening studies. A baseline DEXA study could facilitate longitudinal monitoring of BMD in children, who may be more susceptible than adults to the negative effects of AHSCT on BMD. In addition, given the high risk of BMD impairment in pediatric AHSCT recipients with cGVHD, such patients should undergo BMD evaluation upon developing cGVHD, with continued monitoring thereafter to allow intervention before progression of the BMD impairment to its severe manifestation, VCF.