Spine Dual-energy X-ray Absorptiometry Scans Research Articles

Investigating the triglyceride–glucose index in postmenopausal osteoporosis

Objective This retrospective study aims to assess the association of the triglyceride–glucose index (TyG index) with postmenopausal osteoporosis and investigate longitudinal changes in TyG index levels in relation to osteoporosis risk. Methods Out of 704 women, after excluding those with osteopenia, a total of 517 patients who met the inclusion criteria were included. Participants were categorized based on T-scores derived from lumbar spine dual-energy X-ray absorptiometry scans. Demographic data, biochemical parameters and TyG index levels were analyzed. Logistic regression, correlation analysis and receiver operating characteristic (ROC) curve analysis were employed for statistical evaluation. Results The osteoporosis group (n = 254) exhibited significantly higher TyG index and triglyceride levels compared to controls (n = 263). Longitudinal analysis revealed significant increases in TyG index levels among women developing osteoporosis over time. ROC analysis demonstrated the TyG index’s accuracy for osteoporosis (first TyG area under the curve [AUC]: 0.767, second TyG AUC: 0.818, p < 0.001). Regression analyses identified the TyG index as a significant factor associated with osteoporosis (odds ratio: 39.468, 95% confidence interval: 12.884–120.903, p < 0.001). Conclusions The TyG index emerges as a valuable indicator for postmenopausal osteoporosis. These results emphasize the need for integrating metabolic health indicators into osteoporosis management strategies, warranting further research into targeted interventions.

Abdominal Aorta Calcification Identified on DXA Scans and the Risk of Mortality in Adults.

Abdominal aortic calcification (AAC) on lateral lumbar radiographs increases the risk of cardiovascular events and mortality. However, data on the association between AAC detected in dual energy X-ray absorptiometry (DXA) and the risk of mortality in the general population are scarce. The present study was based on data from participants aged ≥40 years in the National Health and Nutrition Examination Survey (NHANES) cycle of 2013 to 2014. Vertebral assessment of lateral spine DXA scans was used to provide AAC measurements at vertebrae L1-L4. The extent of AAC was defined according to the Kauppila AAC-24 scores (0-1, 2-5, ≥6), and the NHANES 2019 public-use linked mortality files were used to assess mortality status. Of the 2,962 participants who were included in this study, with a mean age of 57.4 years and a median follow-up of 69.9 months, 252 (8.5%) died. Of the deaths, 84 (33.3%) occurred due to cardiovascular disease. The Cox proportional hazards models revealed that participants with AAC-24 scores ≥6 were 1.7 times more likely to die than those with AAC-24 scores 0-1 (Hazard ratio, 1.75; 95% confidence interval, 1.13-2.71). Moreover, older adults and women with AAC-24 scores ≥6 were 2.8 and 2.4 times more likely to die than their counterparts with AAC-24 scores 0-1, respectively. Conversely, a non-significant risk of cardiovascular mortality was found among participants with AAC-24 scores ≥6. The extent of AAC detected on vertebral fracture assessment DXA was associated with an increased risk of all-cause mortality in adults, particularly older adults and women.

Associations of Lean Mass, Muscular Strength, and Physical Function with Trabecular Bone Score in Older Adults

Introduction/Background: Trabecular bone score (TBS) is an indirect measurement of bone quality and microarchitecture determined from dual-energy X-ray absorptiometry (DXA) imaging of the lumbar spine. TBS predicts fracture risk independent of bone mass/density, suggesting this assessment of bone quality adds value to the understanding of patients’ bone health. While lean mass and muscular strength have been associated with higher bone density and lower fracture risk among older adults, the literature is limited regarding the relationship of lean mass and strength with TBS. The purpose of this study was to determine associations of DXA-determined total body and trunk lean mass, maximal muscular strength, and gait speed as a measure of physical function, with TBS in 141 older adults (65-84 yr, 72.5 +/- 5.1 yr, 74% women). Methodology: Assessments included lumbar spine (L1-L4) bone density and total body and trunk lean mass by DXA, lower body (leg press) and upper body (seated row) strength by one repetition maximum tests, hand grip strength, and usual gait speed. TBS was derived from the lumbar spine DXA scan. Multivariable linear regression determined the contribution of proposed predictors to TBS. Results: After adjusting for age, sex, and lumbar spine bone density, upper body strength significantly predicted TBS (unadjusted/adjusted R2= 0.16/ 0.11, β coefficient =0.378, p=0.005), while total body lean mass index showed a trend in the expected direction (β coefficient =0.243, p=0.053). Gait speed and grip strength were not associated with TBS (p>0.05). Conclusion: Maximum strength of primarily back muscles measured as the seated row appears important to bone quality as measured by TBS, independent of bone density. Additional research on exercise training targeting back strength is needed to determine its clinical utility in preventing vertebral fractures among older adults.

Updated trabecular bone score accounting for the soft tissue thickness (TBSTT) demonstrated significantly improved bone microstructure with denosumab in the FREEDOM TBS post hoc analysis

SummaryTBS algorithm has been updated to account for regional soft tissue noise. In postmenopausal women with osteoporosis, denosumab improved tissue thickness–adjusted TBS vs placebo independently of bone mineral density over 3 years, with the magnitude of changes from baseline or placebo numerically greater than body mass index–adjusted TBS.IntroductionTo evaluate the effect of denosumab on bone microarchitecture assessed by trabecular bone score (TBS) in the FREEDOM study using the updated algorithm that accounts for regional soft tissue thickness (TBSTT) in dual-energy X-ray absorptiometry (DXA) images and to compare percent changes from baseline and placebo with classical body mass index (BMI)–adjusted TBS (TBSBMI).MethodsPostmenopausal women with lumbar spine or total hip bone mineral density (BMD) T score < − 2.5 and ≥ − 4.0 received placebo or denosumab 60 mg subcutaneously every 6 months. TBSBMI and TBSTT were assessed on lumbar spine DXA scans at baseline and months 1, 12, 24, and 36 in a subset of 279 women (129 placebo, 150 denosumab) who completed the 3-year FREEDOM DXA substudy and rolled over to open-label extension study.ResultsBaseline characteristics were similar between groups. TBSTT in the denosumab group showed numerically greater changes from both baseline and placebo than TBSBMI at months 12, 24, and 36. Denosumab led to progressive increases in BMD (1.2, 5.6, 8.1, and 10.5%) and TBSTT (0.4, 2.3, 2.6, and 3.3%) from baseline to months 1, 12, 24, and 36, respectively. Both TBS changes were significant vs baseline and placebo from months 12 to 36 (p < 0.0001). As expected, BMD and TBSTT were poorly correlated both at baseline and for changes during treatment.ConclusionIn postmenopausal women with osteoporosis, denosumab significantly improved bone microstructure assessed by TBSTT over 3 years. TBSTT seemed more responsive to denosumab treatment than TBSBMI and was independent of BMD.

Detecting pathological features and predicting fracture risk from dual-energy X-ray absorptiometry images using deep learning

Dual-energy X-ray absorptiometry (DXA) is the gold standard imaging method for diagnosing osteoporosis in clinical practice. The DXA images are commonly used to estimate a numerical value for bone mineral density (BMD), which decreases in osteoporosis. Low BMD is a known risk factor for osteoporotic fractures. In this study, we used deep learning to identify lumbar scoliosis and structural abnormalities that potentially affect BMD but are often neglected in lumbar spine DXA analysis. In addition, we tested the approach's ability to predict fractures using only DXA images. A dataset of 2949 images gathered by Kuopio Osteoporosis Risk Factor and Prevention Study was used to train a convolutional neural network (CNN) for classification. The model was able to classify scoliosis with an AUC of 0.96 and structural abnormalities causing unreliable BMD measurement with an AUC of 0.91. It predicted fractures occurring within 5 years from the lumbar spine DXA scan with an AUC of 0.63, meeting the predictive performance of combined BMD measurements from the lumbar spine and hip. In an independent test set of 574 clinical patients, AUC for lumbar scoliosis was 0.93 and AUC for unreliable BMD measurements was 0.94. In each classification task, neural network visualizations indicated the model's predictive strategy. We conclude that deep learning could complement the well established DXA method for osteoporosis diagnostics by analyzing incidental findings and image reliability, and improve its predictive ability in the future.

Prevalence and Predictors of Compromised Bone Mineral Density in Pediatric Eosinophilic Esophagitis.

The aim of the study was to determine whether patients with eosinophilic esophagitis (EoE) have lower bone mineral density (BMD) than expected and if bone deficits are more pronounced in subgroups of patients according to comorbidities (atopic disease and joint hypermobility) or treatments (dietary restriction, medication exposure). Retrospective chart review was performed to obtain clinical data, including length of diagnosis, comorbidities, and methods of treatment for patients with EoE ages 3 to 21 years who had a lumbar spine dual-energy x-ray absorptiometry scan performed between 2014 and 2017. BMD was standardized by calculation of age, sex, and race-specific z scores. A total of 269 patients met study criteria. The mean BMD z score (-0.55, 95% confidence interval: -0.68, -0.42) was lower than expected (P < 0.0001), and the prevalence of low BMD z score (≤-2.0) was higher than expected (8.5%, 95% confidence interval: 5.2%-11.9%, P < 0.0001). In multivariable regression models, BMD z scores were -0.27 lower among those following an elimination diet and -0.65 lower among those with any lifetime use of a proton pump inhibitor (93% of the sample). There was no association with swallowed steroid use. In our sample, pediatric patients with EoE had a slightly lower BMD z score compared to peers, and the prevalence of low BMD was higher than expected. Taken cautiously given the limitations of our sample, risk factors for bone deficits included any lifetime use of proton pump inhibitor and a restrictive elimination diet, but not swallowed steroid use. Larger prospective studies are needed to better characterize risk factors for low BMD to help inform screening, selection of therapies, and provide appropriate anticipatory guidance for patients with EoE.

Trabecular Bone Score And Bone Mineral Density In Older Adults

The Trabecular Bone Score (TBS) is an estimate of the healthiness of bone microarchitecture that is based on the mathematical reconstruction of 3D micro-computed tomography (μCT) scans using 2D Dual-energy X-ray Absorptiometry (DXA). Compared to bone mineral density (BMD), TBS is a relatively new DXA-derived metric for predicting fracture risk. PURPOSE: This study examined the associations between classically measured vertebral bone mineral density (BMD) and TBS in inactive older adults. METHODS: For the present analyses, we included pre-training data from 19 older adults (X±SD; 71±4.2y, 4 black, 6 males) participating in an ongoing exercise intervention (REALPA). Whole-body and lumbar spine scans were acquired using a Hologic Horizon®A DXA scanner to determine BMD. TBS iNsight™ was used to determine the TBS score from lumbar spine DXA scans. Multivariate analyses were used to determine associations between whole-body and lumbar spine BMD with TBS scores, and sex differences were assessed by t-tests. RESULTS: A strong correlation between both whole-body BMD and lumbar spine TBS (r=0.815, p<0.0001) was observed; this was also true for lumbar spine BMD and lumbar spine TBS (r=0.834, p<0.0001). Sex differences were found (males vs. females) for Whole-body BMD (g/cm2; 1.156±0.12 vs 0.972±0.10, p<0.009), lumbar spine BMD (1.150±0.20 vs 0.920±0.15, p<0.05), and lumbar spine TBS (1.409±0.10 vs 1.285±.09, p<0.05). CONCLUSION: The sex differences for BMD and TBS are consistent with the literature, with males having higher BMD and TBS. Strong correlations between BMD and TBS suggest that TBS bone has construct validity. However, future studies are still warranted to determine whether TBS scoring provides clinically meaningful insight into fracture risk beyond traditional BMD. Furthermore, future research studies are warranted to determine whether exercise induced changes TBS are sensitive markers for exercise induced bone remodeling, which would provide additional insight into the clinical utility of TBS. This study was supported by the NIH 5R21AG058181-02.

Progressive bone impairment with age and pubertal development in neurofibromatosis type I.

The present study aims at evaluating bone mineral density (BMD) in a population of children with neurofibromatosis type I (NF-1), with particular focus on changes occurring during growth and pubertal development. Bone metabolic markers and bone status [by dual-energy X-ray absorptiometry scans (DXA) of the total body and lumbar spine with morphometric analysis] were assessed in 50 children (33 males; mean age ± SD, 11.6 ± 4years). Bone mineral apparent density (BMAD), trabecular bone score (TBS), and bone strain (BS) of the lumbar spine (LS) DXA were also obtained. In our cohort areal BMD (aBMD) Z-score was below the mean in 88% of the patients at LS (70% after correction for bone size) and in 86% considering total body (TB) DXA. However, aBMD Z-score was < - 2 in 12% after correction for bone size at LS and TB, respectively. Lumbar spine aBMD Z-score (r = - 0.54, P < 0.0001), LS BMAD Z-score (r = - 0.53, P < 0.0001), and TB Z-score (r = - 0.39, P = 0.005) showed a negative correlation with growth and pubertal development (P = 0.007, P = 0.02, P= 0.01, respectively), suggesting that patients failed to gain as much as expected for age. Bone density impairment becomes more evident with growth and pubertal development in NF-1 patients, thus identifying childhood as the best time frame to introduce prevention strategies aiming at peak bone mass achievement. TBS and BS, providing bone DXA qualitative information, could be useful during longitudinal follow-up for better characterizing bone impairment in these patients.

Effect of denosumab on trabecular bone score in postmenopausal women with osteoporosis.

TBS, a gray-level texture index determined from lumbar spine DXA scans, correlates with bone microarchitecture and enhances assessment of vertebral fracture risk independently of BMD. In the FREEDOM study, denosumab increased BMD and reduced new vertebral fractures in postmenopausal women with osteoporosis. This retrospective analysis explored the effect of denosumab on TBS and the association between TBS and BMD in FREEDOM. Postmenopausal women with lumbar spine or total hip BMD T-score <-2.5 and -4.0 or higher at both sites received placebo or denosumab 60mg subcutaneously every 6months. TBS indices were determined from DXA scans at baseline and months 12, 24, and 36 in a subset of 285 women (128 placebo, 157 denosumab) who had TBS values at baseline and ≥1 postbaseline visit. Baseline characteristics were comparable between treatment groups; mean (SD) lumbar spine BMD T-score was -2.79 (0.64), and mean (standard deviation [SD]) TBS was 1.200 (0.101) overall. In the placebo group, BMD and TBS increased by ≤0.2% or decreased from baseline at each visit. In the denosumab group, progressive increases from baseline at 12, 24, and 36months were observed for BMD (5.7, 7.8, and 9.8%) and TBS (1.4, 1.9, and 2.4%). Percentage changes in TBS were statistically significant compared with baseline (p<0.001) and placebo (p≤0.014). TBS was largely unrelated to BMD, regardless of treatment, either at baseline or for annual changes from baseline (all r 2≤0.06). In postmenopausal women with osteoporosis, denosumab significantly improved TBS independently of BMD.

Relationships among diet, physical activity, and dual plane dual-energy X-ray absorptiometry bone outcomes in pre-pubertalgirls.

Childhood development sets the baseline for adult fracture risk. Most studies evaluate development using postero-anterior (PA) dual-energy X-ray absorptiometry (DXA) areal bone mineral density, bone mineral content, and bone mineral apparent density. In a prior analysis, we demonstrated that PA DXA reflects posterior element properties, rather than vertebral body fracture sites, such that loading is associated with subtle differences in vertebral body geometry, not 3D density. The current analysis is restricted to pre-pubertal girls, for a focused exploration of key nutrient intakes and physical activity as factors in dual plane indices of vertebral body geometry, density, and strength. This cross-sectional analysis used paired PA and supine lateral (LAT) lumbar spine DXA scans to assess "3D" vertebral body bone mineral apparent density (PALATBMAD), "3D" index of structural strength in axial compression (PALATIBS), and fracture risk index (PALATFRI). Diet data were collected using the Youth/Adolescent Questionnaire (YAQ, 1995); organized physical activity was recorded via calendar-based form. Pearson correlations and backward stepwise multiple linear regression analyzed associations among key nutrients, physical activity, and bone outcomes. After accounting for activity and key covariates, fiber, unsupplemented vitamin B12, zinc, carbohydrate, vitamin C, unsupplemented magnesium, and unsupplemented calcium intake explained significant variance for one or more bone outcomes (p<0.05). After adjustment for influential key nutrients and covariates, activity exposure was associated with postero-anterior (PA) areal bone mineral density, PA bone mineral content, PA width, lateral (LAT) BMC, "3D" bone cross-sectional area (coronal plane), "3D"PALATIBS, and PALATFRI benefits (p<0.05). Physical activity, fiber intake, and unsupplemented B12 intake appear to influence vertebral body bone mass, density, geometry, and strength in well-nourished pre-pubertal girls; high fiber intakes may adversely affect childhood vertebral body growth.

Influence of Chronic Recurrent Multifocal Osteomyelitis (CRMO) On Densitometry Measurements Obtained by Dual X-Ray Absorptiometry

The incidence of detecting focal chronic recurrent multifocal osteomyelitis (CRMO) lesions on dual-energy x-ray absorptiometry (DXA), and the effect of these lesions on DXA bone mineral density (BMD), bone mineral content (BMC), and their associated Z-scores were retrospectively reviewed. Materials and Methods. The study included 22 patients (14 females, 8 males; median age of 13 years) with CRMO and in whom a total body less head (TBLH) and lumbar spine DXA scan had been obtained. Whole-body bone scintigraphy and MRI were used as the reference standards. Sites involved with CRMO were subsequently detected and DXA measurements were re-measured after removing the sclerotic lesions from the analysis. Results. In total, sclerotic CRMO lesions were detected in 15 of the 22 patients (68%) by DXA, although the number of lesions detected (on a per-lesion analysis) was much less (i.e. 29 of 129 lesions; 19.4%) when compared to MRI and/or bone scintigraphy. Larger lesions had a greater impact on the derived BMD/BMC measurements, and changed the diagnosis in one patient from having normal to abnormal DXA results based on the final Z-score. Discussion. CRMO lesions detected on DXA examinations should be regarded as a potential source of error. Careful inspection and re-quantification of the BMD, BMC and associated Z-score after applying an appropriate correction should be considered in patients with large CRMO lesions identified on DXA examinations.

Densitometer-Specific Differences in the Correlation Between Body Mass Index and Lumbar Spine Trabecular Bone Score

Trabecular bone score (TBS) is a gray-level texture measure derived from lumbar spine dual-energy X-ray absorptiometry (DXA) images that predicts fractures independent of bone mineral density (BMD). Increased abdominal soft tissue in individuals with elevated body mass index (BMI) absorbs more X-rays during image acquisition for BMD measurement and must be accommodated by the TBS algorithm. We aimed to determine if the relationship between BMI and TBS varied between 2 major manufacturers' densitometers, because different densitometers accommodate soft tissues differently. We identified 1919 women and 811 men, participants of the Canadian Multicentre Osteoporosis Study, aged ≥40 yr with lumbar spine DXA scans acquired on GE Lunar (4 centers) or Hologic (3 centers) densitometers at year 10 of follow-up. TBS was calculated for L1–L4 (TBS iNsight® software, version 2.1). A significant negative correlation between TBS and BMI was observed when TBS measurements were performed on Hologic densitometers in men (Pearson r = −0.36, p < 0.0001) and in women (Pearson r = −0.33, p < 0.0001); significant correlations were not seen when TBS was measured on GE Lunar densitometers (Pearson r = 0.00 in men, Pearson r = −0.02 in women). Age-adjusted linear regression models confirmed significant interactions between BMI and densitometer manufacturer for both men and women (p < 0.0001). In contrast, comparable positive correlations were observed between BMD and BMI on both Hologic and GE Lunar densitometers in men and women. In conclusion, BMI significantly affects TBS values in men and women when measured on Hologic but not GE Lunar densitometers. This finding has implications for clinical and research applications of TBS, especially when TBS is measured sequentially on DXA densitometers from different manufacturers or when results from different machines are pooled for analysis.

Advanced Analysis Techniques Improve Infant Bone and Body Composition Measures by Dual-Energy X-Ray Absorptiometry

To evaluate a novel technique designed to reduce the negative impact of motion artifacts in infant dual-energy X-ray absorptiometry (DXA) scans. Using cross-sectional data from a large multicenter study, we developed and tested advanced methods for infant scan analysis. Newborns (n = 750) received spine and whole-body DXA scans with up to 3 attempts to acquire a motion free scan. Precision of infant DXA was estimated from visits with multiple valid scans. Accuracy of regional reflection, fusion, and omission techniques was estimated by comparing modified scans to unmodified valid scans. The effectiveness of the acquisition and analysis protocol was represented by the reduction in rate of failure to acquire valid results from infant visits. For infant whole-body DXA, arm reflection and all fusion techniques caused no significant changes to bone mineral content, bone mineral density, bone area, total mass, fat mass, lean mass, and percentage fat. Leg reflection and arm/leg dual-reflection caused significant changes to total mass, but the percentage change remained small. For infant spine DXA, fusion and omission caused no significant changes. Advanced analysis techniques reduced the failure rate of whole-body scanning from 20.8% to 9.3% and the failure rate of spine scanning from 8.9% to 2.4%. Advanced analysis techniques significantly reduced the impact of motion artifacts on infant DXA scans. We suggest this protocol be used in future infant DXA research and clinical practice.

Anthropometric adjustments are helpful in the interpretation of BMD and BMC Z-scores of pediatric patients with Prader-Willi syndrome.

Bone mineral density (BMD) is decreased in patients with Prader-Willi syndrome (PWS). Because of largely abnormal body height and weight, traditional BMD Z-scores may not provide accurate information in this patient group. The goal of the study was to assess a cohort of individuals with PWS and characterize the development of low bone density based on two adjustment models applied to a dataset of BMD and bone mineral content (BMC) from dual-energy X-ray absorptiometry (DXA) measurements. Fifty-four individuals, aged 5-20years with genetically confirmed PWS, underwent DXA scans of spine and hip. Thirty-one of them also underwent total body scans. Standard Z-scores were calculated for BMD and BMC of spine and total hip based on race, sex, and age for all patients, as well as of whole body and whole-body less head for those patients with total-body scans. Additional Z-scores were generated based on anthropometric adjustments using weight, height, and percentage body fat and a second model using only weight and height in addition to race, sex, and age. As many PWS patients have abnormal anthropometrics, addition of explanatory variables weight, height, and fat resulted in different bone classifications for many patients. Thus, 25-70% of overweight patients, previously diagnosed as normal, were subsequently diagnosed as below normal, and 40-60% of patients with below-normal body height changed from below normal to normal depending on bone parameter. This is the first study to include anthropometric adjustments into the interpretation of BMD and BMC in children and adolescents with PWS. This enables physicians to get a more accurate diagnosis of normal versus abnormal BMD and BMC and allows for early and effective intervention.

Trabecular bone score in healthy ageing.

The main aim of this work was to report on trabecular bone score (TBS) by dual-energy X-ray absorptiometry (DXA) of healthy Italian subjects to be used as a reference standard for future study in clinical and research settings. The secondary aim was to investigate the link between TBS and conventional parameters of bone and body composition by DXA. 250 individuals of 5 age bands (spanning from 18 to 70 years of age, equally distributed for both age and sex) were prospectively recruited. A lumbar spine (LS) DXA scan (Lunar iDXA™; GE Healthcare, Madison, WI) was acquired for each subject and then analysed with the latest version of TBS iNsight v. 2.1 (Med-Imaps, Pessac, France) software. LS bone mineral density (LS BMD), Z-score, T-score and TBS values were collected. Pearson's test was used to investigate the correlations between TBS and LS BMD and the influence of age, body mass index (BMI) and body composition on these parameters. A significant decrease of TBS and LS BMD was observed with ageing in both males (TBS mean values from 1.486 to 1.374; LS BMD mean values from 1.219 to 1.187) and females (TBS mean values from 1.464 to 1.306; LS BMD mean values from 1.154 to 1.116). No statistically significant difference was achieved among males and females of the same age group for both TBS and LS BMD, with the exception of the fifth age group. A significant correlation was found between LS BMD and TBS values in both sexes (r = 0.555-0.655, p < 0.0001). BMI influenced LS BMD but not TBS. TBS values were inversely correlated with some fat mass parameters, in particular with visceral adipose tissue (in males: r = -0.332, p < 0.001; in females: r = -0.348, p < 0.0001). No significant correlation was found between TBS and total lean mass, opposite to LS BMD (in males: r = 0.418; p < 0.0001; in females: r = -0.235; p < 0.001). This report is an attempt to start building a database for healthy Italian people providing age- and sex-specific reference curves for TBS. This could help clinicians to improve patient management in the detection of impaired bone mineral status and to monitor bone changes. The study reports TBS values of a selectively enrolled Italian healthy population, ranging from younger to older ages and including males as a reference standard. Moreover, links between body composition and TBS are explored.

Spine-Hip Thickness Difference Measured by Dual-Energy X-ray Absorptiometry Is Associated With Diabetes Mellitus in Women and Men

Abdominal adiposity is strongly associated with a range of chronic metabolic and cardiovascular morbidities, including type 2 diabetes mellitus, and may play a causal role in their development. Dual-energy X-ray absorptiometry (DXA) of the lumbar spine and hip is widely used for assessment of osteoporosis and also measures tissue thickness. We hypothesized that the difference in spine and hip tissue thickness from regional DXA scans might provide an index of relative abdominal adiposity and serve as a risk factor for the presence of diabetes. We identified 31,648 women and 2960 men aged ≥50 yr who underwent spine and hip DXA scans and analyzed their baseline characteristics, including presence of previously diagnosed diabetes in 2929 women and 460 men. Women had significantly lower mean spine-hip thickness differences than men (3.3 ± 1.4 cm vs 5.4 ± 1.7 cm; p < 0.001), which persisted after adjustment for sex-specific differences in the effects of age and body mass index (BMI). Women and men with diabetes had significantly higher mean spine-hip thickness differences before and after adjustment for age and BMI. Logistic regression showed that greater spine-hip thickness difference was significantly associated with higher likelihood of diabetes even after adjustment for age and BMI, and this effect was stronger among women (odds ratios per standard deviation 1.88 [95% confidence interval: 1.86–1.98]; p < 0.001) than among men (1.10 [1.03–1.18]; p = 0.007). We conclude that spine-hip thickness difference measured from regional DXA scans warrants further study as a risk factor for developing diabetes.

Trabecular Bone Score (TBS) Predicts Vertebral Fractures in Japanese Women Over 10 Years Independently of Bone Density and Prevalent Vertebral Deformity: The Japanese Population-Based Osteoporosis (JPOS) Cohort Study

Bone strength is predominantly determined by bone density, but bone microarchitecture also plays an important role. We examined whether trabecular bone score (TBS) predicts the risk of vertebral fractures in a Japanese female cohort. Of 1950 randomly selected women aged 15 to 79 years, we analyzed data from 665 women aged 50 years and older, who completed the baseline study and at least one follow-up survey over 10 years, and who had no conditions affecting bone metabolism. Each survey included spinal imaging by dual-energy X-ray absorptiometry (DXA) for vertebral fracture assessment and spine areal bone mineral density (aBMD) measurement. TBS was obtained from spine DXA scans archived in the baseline study. Incident vertebral fracture was determined when vertebral height was reduced by 20% or more and satisfied McCloskey-Kanis criteria or Genant's grade 2 fracture at follow-up. Among eligible women (mean age 64.1 ± 8.1 years), 92 suffered incident vertebral fractures (16.7/10(3) person-years). These women were older with lower aBMD and TBS values relative to those without fractures. The unadjusted odds ratio of vertebral fractures for one standard deviation decrease in TBS was 1.98 (95% confidence interval [CI] 1.56, 2.51) and remained significant (1.64, 95% CI 1.25, 2.15) after adjusting for aBMD. The area under the receiver operating characteristic curve of TBS and aBMD combined was 0.700 for vertebral fracture prediction and was not significantly greater than that of aBMD alone (0.673). However, reclassification improvement measures indicated that TBS and aBMD combined significantly improved risk prediction accuracy compared with aBMD alone. Further inclusion of age and prevalent vertebral deformity in the model improved vertebral fracture prediction, and TBS remained significant in the model. Thus, lower TBS was associated with higher risk of vertebral fracture over 10 years independently of aBMD and clinical risk factors including prevalent vertebral deformity. TBS could effectively improve fracture risk assessment in clinical settings.

Intervertebral T-Score Differences in Younger and Older Women

The T-score discordance among skeletal sites is an important aspect of dual-energy X-ray absorptiometry (DXA) measurements. In the spine, large T-score differences between vertebrae are frequently seen in elderly patients owing to degenerative disease. However, it is unclear how often such differences occur in younger adults with healthy spines.The T-scores for individual lumbar vertebrae were compared for 2391 female singletons (18–79yr) recruited to the Twins UK Adult Twin Register. Women were divided into 6 age bands and 5 bands by body weight, respectively, and the T-score differences between the pairs of vertebrae were examined using correlation coefficients and the standard error of the estimate (SEE) from linear regression analysis.Correlations between the T-scores for adjacent lumbar vertebrae were r=0.92 decreasing to r=0.79 between L1 and L4. When plotted as a function of age, r-values were constant for the 5 younger age bands, but decreased in the oldest group. In contrast, the T-score SEE values increased progressively with age from 0.4 to 0.5 for the younger groups to 0.7 for the oldest. Similar trends were seen when women were divided according to body weight. Both increasing age and higher body weight were statistically significantly associated with a higher T-score SEE.The incidence of large T-score differences between vertebrae varies with age and body weight, but is common even among younger women. Clinically significant T-score differences can occur in the absence of osteoarthritis, and visual assessment of spine DXA scans for evidence of degenerative disease is advised before vertebrae are omitted from scan analyses.

Assessment of dual-energy X-ray absorptiometry measures of bone health in pediatric chronic kidney disease.

Dual-energy X-ray absorptiometry (DXA) techniques are limited in childhood chronic kidney disease (CKD) by the confounding effect of short stature and opposing parathyroid hormone effects on trabecular and cortical bone. Peripheral quantitative computed tomography (pQCT) is not subject to these limitations. Lumbar spine (LS) and whole-body (WB) DXA and tibia pQCT scans were obtained in 88 stage 4-5 CKD and >650 healthy participants, ages 5-21 years. Sex- and race-specific Z-scores were generated for bone mineral density (BMD) and bone mineral content (BMC) by DXA, relative to age and adjusted for height Z-score (LS-BMD-Z and WB-BMC-Z), and compared to pQCT Z-scores for trabecular BMD (TrabBMD-Z) for age and cortical BMC (CortBMC-Z) for age and tibia length. LS-BMD-Z [0.50 (95% C.I. 0.28, 0.73), p<0.0001] and TrabBMD-Z [0.53 (0.27, 0.79), p<0.0001] were greater in CKD, and WB-BMC-Z [-0.36 (-0.53, -0.19), p<0.0001] and CortBMC-Z [-0.48 (-0.70, -0.27), p<0.0001] were lower, compared to reference participants. Z-scores were correlated at trabecular (LS-BMD-Z and TrabBMD-Z: R=0.36) and cortical (WB-BMC-Z and CortBMC-Z: R=0.64) sites in CKD; similar to correlations in reference participants. Lumbar spine and whole-body DXA suggested greater trabecular BMD and lower cortical BMC in CKD, consistent with pQCT results; however, correlations were modest. Studies are needed to identify methods that predict fracture in childhood CKD.

Abdominal Fat from Spine Dual-Energy X-Ray Absorptiometry and Risk for Subsequent Diabetes

Abdominal obesity is a major risk factor for diabetes. Dual-energy x-ray absorptiometry (DXA) of the lumbar spine provides an index of abdominal fat. Our objective was to examine the hypothesis that DXA-derived abdominal fat measurement in women undergoing osteoporosis investigation predicts risk for subsequent diagnosis of diabetes. This historical cohort study was derived from the Manitoba Bone Density Program Database for the Province of Manitoba, Canada. 30,252 nondiabetic women aged 40 yr and older were referred for baseline osteoporosis assessment with DXA between January 1990 and March 2007. Each woman's longitudinal provincial health service record was assessed for the presence of diabetes diagnosis codes after DXA testing. During 5.2 + or - 2.6 yr of observation, 1252 (4.1%) women met the case definition for diabetes. A greater proportion of abdominal fat from spine DXA was strongly related to subsequent diabetes diagnosis in models adjusted for age, body mass index, and other comorbidities. Those in the highest quintile had 3.56 (95% confidence interval = 2.67-4.75) times the risk for subsequent diabetes diagnosis compared with those in the lowest (reference) quintile. Fat from hip DXA was not predictive of subsequent diabetes after adjustment for the same variables (1.00, 95% confidence interval = 0.79-1.26). Predictive information about diabetes risk can be obtained from spine DXA scans performed for osteoporosis risk assessment. This is consistent with evidence linking abdominal fat with insulin resistance and the metabolic syndrome.