Lunar Prodigy Dual-energy X-ray Absorptiometry Research Articles

Reference values of body composition parameters and visceral adipose tissue (VAT) by DXA in adults aged 18\u201381 years\u2014results from the LEAD cohort

BackgroundIncreasing attention has been drawn on the assessment of body composition phenotypes, since the distribution of soft tissue influences cardio-metabolic risk. Dual-energy X-ray absorptiometry (DXA) is a validated technique to assess body composition. European reference values from population-based cohorts are rare.AimsTo provide age- and sex-related reference values of body composition parameters and visceral adipose tissue (VAT) mass, and for lean mass index (LMI) with regard to fat mass index (FMI) quantities and BMI categories.MethodsGE-Lunar Prodigy DXA scans of 10.894 participants, aged 18–81 years, recruited from 2011 to 2019 by the Austrian LEAD study, a population-based cohort study, have been used to construct reference curves using the LMS method. Parameters assessed are FMI, LMI, appendicular LMI, fat mass ratios android/gynoid and trunk/limbs, and VAT.ResultsAll lean mass and fat mass parameters indicating central fat accumulation were higher in men, whereas other fat mass indices were higher in women. LMI differed between each FMI subgroup (low vs. normal, low vs. high, normal vs. high), and BMI category in all ages and LMI increased with FMI and BMI classes. VAT mass was higher in men compared with women and increased across all age groups within both sexes.ConclusionThe present study provides age- and sex-related reference values for European adults aged 18–81 years for body composition parameters and VAT mass for Lunar Prodigy DXA. In addition, this study reports LMI reference values with regard to fat mass quantities, showing a positive association with increasing FMI percentiles and BMI categories.

Dual-energy X-ray absorptiometry is a reliable non-invasive technique for determining whole body composition of chickens

In this study, a Lunar Prodigy dual-energy X-ray absorptiometry (DEXA) scanner was validated as a technique to estimate chicken body composition in a non-invasive way. Former research has emphasized the importance of validation of every scanner and software version. In a first trial, DEXA estimated body composition for broilers was correlated with chemical carcass analysis to develop prediction equations. As such, those equations can be used in later experiments with chickens to correct DEXA estimations to estimate body composition accurately by DEXA. DEXA estimated fat mass, lean tissue mass, bone mineral content (BMC) and total body mass, which is the sum of fat, lean mass and BMC, were compared to chemically analyzed crude fat, lean mass as the sum of protein and water and body ash content and scale body weight, respectively. Those regression equations were then used in a second trial to determine body composition based upon DEXA for breeders at different ages. In this experiment, fat and lean tissue determined by DEXA, were compared to dissection parameters commonly used for assessing carcass quality, namely breast muscle and abdominal fat. The first trial showed that DEXA provides high correlations for body mass (ρ = 1) and the individual tissue masses separately (ρ ranging between 0.98 and 1). These high correlations allow for accurate prediction of those components with the developed regression equations. Proportional fat and lean tissue were correlated with their chemical counterparts, however, to a lower extent than absolute values due to lower variation between the proportional weights. BMC percentage was not significantly correlated with ash percentage. Furthermore, in trial 2 high correlations were observed between dissection parameters and DEXA-corrected estimations. These correlations show that DEXA can assess carcass quality in breeders without sacrificing the birds. In conclusion, DEXA is a reliable technique to estimate breeder and broiler body composition in a non-invasive way, hence allowing for longitudinal studies over longer periods of time while avoiding sacrificing of birds.

Do we need to perform bilateral hip bone mineral density examination?

Background: Bone mineral density (BMD) measurement is one of the method for making osteoporosis diagnosis. World Health Organization (WHO) recommends the measurement of BMD conducted at antero-posterior lumbar vertebrae, unilateral hip (femur), and radius. However, there was a concern about osteoporosis under diagnosis if the measurement is only conducted at unilateral hip. Some studies found significant differences of BMD between both femur and evidence of the importance to examine both femur in making the diagnosis of osteoporosis. This study aims to determine anydifference between right and left femur BMD measurement and to investigate the bone status result with measurement of BMD of bilateral femur in Hasan Sadikin General Hospital. Methods: A retrospective study was conducted from June to November 2015. Patients who received dual-femur BMD testing using General Electrics (GE) Lunar Prodigy dual-energy x-ray absorptiometry at the DXA Facility in Hasan Sadikin General Hospital,Bandung between January 1, 2006 to December 31, 2014 were included. Statistical analysis performed to assess the difference and the correlation between theBMD of two femurs (g/cm2). T-scores of the subject were implemented into bone status according to WHO Diagnostic Criteria for Osteoporosis.Results: From sixty-one patients included in this study, there were difference bone status resulted from BMD of the femoral neck, Ward’s triangle, trochanter, andtotal hip area between right and left femur, although no statistically significance were found. There was a positive correlation between BMD of right and left femurat all areas of femur. There were 16 subjects (26.1%) showed combination level of bone status (normal, osteopenia, or osteoporosis in one femur).Conclusion: BMD results in each area of the right and left femurs are different.Therefore, performing bilateral hip BMD examination as a routine measurement for makingdiagnosis of osteoporosis is important.Keywords: Bone Mineral Density, Dual-energy X-ray Absorptiometry, Femur, Osteoporosis

Repeatability of Volume and Regional Body Composition Measurements of the Lower Limb Using Dual-energy X-ray Absorptiometry

Lower limb lymphedema is a dynamic condition in which tissue composition and volume measurements are affected. Various definitions of lower limb lymphedema exist but volume differences between the limbs are widely used. It is therefore necessary to have a readily available noninvasive measurement technique allowing multiple measurements of the lower limbs. This study investigated the repeatability of duplicate volume and regional body composition measurements of the lower limb using the GE Lunar Prodigy dual-energy X-ray absorptiometry (DXA) scanner Prodigy (GE Medical Systems, Madison, WI). Twenty-seven participants (54 limbs), 14 women and 13 men aged 33–71 years with body mass index ranging from 14 to 32 kg/m2 were recruited. Duplicate whole-body DXA scans were performed with repositioning between examinations. Regions of interest were manually drawn for the thigh, lower leg, and foot, and total volume was calculated using the density of bone mineral content, fat, and lean mass. The repeatability of the volume of the lower limb and regional thigh and lower leg tissue composition (bone mineral content, fat, and lean mass) was good with intraclass correlation coefficient values of 0.97 to 0.99, and narrow limits of agreement on the Bland–Altman plots. These results confirm DXA to be a highly repeatable method for volume and tissue composition measurements of the lower limb. In a population at risk of lymphedema, DXA offers a clinically readily available noninvasive method allowing multiple measurements of volume and tissue composition on a routine basis, important for diagnosing, monitoring, managing, and researching lymphedema.

Differences In Body Composition Analysis Between Underwater Weighing, Dual-energy X-ray Absorptiometry, And Two Bioelectrical Impedance Devices In Overweight Young Adults

PURPOSE: As the prevalence of obesity rises, as does the need for reliable body composition (BC) methods. Many methods of BC analysis exist, however accuracy is questioned with respect to which criterion method is referenced by the device. There is often debate within the scientific literature about which criterion method and BIA field measurement is applicable for the overweight population. Little research has been found comparing two debated criterion methods with field methods in overweight or obese individuals. The purpose of this study is to compare criterion methods, hydrostatic weighing (HW) and dual energy x-ray absorptiometry (DXA) with two methods of bioelectrical impedance analysis (BIA) in overweight or obese young adults to determine the validity of these methods. METHODS: N=25 overweight and obese adults (BMI 29.04 ± 3.568kg/m2, 13 males, 12 females, ages 24.37 ± 4.924y) followed standardized pre-testing guidelines for BC assessment. Percent body fat (%BF) was estimated by Omron BIA, Impedimed BIA and compared to GE Lunar Prodigy DXA, and HW. %BF was estimated using generalized population specific equations. RESULTS: Repeated measures ANOVA with a Greenhouse-Geisser correction determined there was a significant mean difference between BC methods. Pairwise comparisons indicated significant differences (p<0.05) between Omron BIA and Impedimed, Omron BIA and DXA, and between HW and DXA. Furthermore, %BF was significantly correlated between Omron BIA and HW (p<0.05, r=0.902) as well as between Impedimed BIA and DXA (p<0.05, r=0.709). CONCLUSIONS: The results of this study show criterion methods, HW and DXA were found to be statistically different from one another. Depending upon which criterion method is referenced, the appropriate field measurement Omron BIA or Impedimed BIA should be selected.

Dual Energy X-Ray Absorptiometry Analysis of Broiler Breeder Eggs for Prediction of Egg Components and Evaluation of Egg Shell Quality

3 Abstract: Most methods for evaluating shell quality and egg components are destructive and time consuming. Four trials were conducted to investigate the use of Dual Energy X-ray Absorptiometry (DXA) as a fast and non-destructive method for evaluating shell quality and measuring the components of broile r breeder eggs. In Trial 1, 180 eggs were scanned with a GE Lunar Prodigy DXA. The eggs were also evaluated by traditional methods that required breaking the eggs for shell quality evaluation and egg components (shell, albumen and yolk) weighed. Values obtained from the DXA scans were subjected to stepwise regression analysis to develop prediction equations. Prediction equations were developed for the weight of egg components (egg, yolk, albumen and shell) and parameters of shell quality (shell weight, thickness and calcium content). In Trial 1, the r values for the prediction equations using DXA values were 2 0.9961, 0.9692, 0.9843, 0.6891, 0.8499 and 0.5738 for the total egg weight, shell weight, shell calcium content, shell thickness, albumen weight and yolk weight, respectively (P>F, F, <0.0001). In Trial 3, 25 0 hatching eggs were scanned to determine the affect of scanning on hatchability. DXA scanning had no negative effect on hatchability, hatch chick weight or hatch residue breakout. In Trial 4, the specific gravity of 400 hatching eggs was determined by flotation in salt solutions. The eggs were then scanned with the DXA and values obtained from these scans were used to calculate SWUSA and shell:egg weight ratios. The SWUSA and shell:egg weight ratios determined by DXA scan were useful in predicting eggshell quality and correlated closely with actual specific gravity values (r = 0.7849, p<0.0001). A SWUSA of 75.1 and specific gravity of 1.081 corresponded to a shell:egg weight ratio of 0.0895 and 0.0924, respectively. Following the evaluation of egg shell quality by DXA and specific gravity, the 400 eggs were incubated to determin e hatchability. Shell:egg weight ratios less than 0.0895 significantly increased the number of early dead (p = 0.02) during the hatchability study. By defining the scan area it is possible to scan and analyze 140 eggs per hour for all egg components and shell quality. DXA offers the primary breeder or researcher a method for selecting individual hens, based on egg component and shell quality profiles, which may improve the performance of the progeny.

DXA Femoral Neck Strength Analysis in Chinese Overweight and Normal Weight Adolescents

The aim of this study was to compare femoral neck (FN) strength in Chinese overweight adolescents with gender-matched normal weight controls and investigate the relationship of total body soft tissue composition (lean and fat masses) to indices of FN strength. Dual-energy X-ray absorptiometry (DXA) measurements of the proximal femur and total body were made in 65 Chinese overweight adolescents and 89 gender-matched normal weight controls using Lunar Prodigy DXA bone densitometer (GE Healthcare, Madison, WI). FN bone mineral density (BMD), total body lean mass, fat mass, and bone mineral content (BMC) were measured. Using FN BMD values derived from DXA measurements, hip structural analysis (HSA) was performed using Lunar enCORE (GE Healthcare), version 10.5 software. Structural parameters derived by HSA were bone cross-sectional area (CSA), cross-sectional moment of inertia (CSMI), and the section modulus (Z). Data were analyzed by Student’s t-test, Pearson correlation coefficients (r), and one-way analysis of covariance (ANCOVA). Overweight boys and girls had higher body weight, lean mass, fat mass, and body mass index (p<0.001) than normal controls. CSA, CSMI, and Z were higher in overweight groups compared with controls (p<0.05). Lean mass correlated well with all HSA parameters (range of r: 0.501–0.714) for both genders. ANCOVA test showed no significant differences between overweight and normal weight groups regarding HSA variables in both genders after adjustment for lean mass. However, the differences remain significant after adjustment for fat mass in boys but not in girls. This study supports the conclusion that overweight individuals have greater hip neck strength in comparison with normal weight controls in Chinese adolescents. Lean mass is a major determinant for FN strength.

Evaluation of Standardization Equations as a Substitute for Scanner Specific In Vivo Measurements

We quantified confidence intervals (CIs) for T-scores for the lumbar spine and hip and determined the practical effect (impact on diagnosis) of variability around the T-score cutpoint of −2.5. Using precision data from the literature for GE Lunar Prodigy dual-energy X-ray absorptiometry (DXA) systems, the 95% CI for the T-score was ±0.23 at the lumbar spine (L1–L4), ± 0.20 at the total hip, and ±0.41 at the femoral neck. Thus, T-score variations of ±0.23 or less at the spine, ±0.20 at the total hip, and ±0.41 at the femoral neck are not statistically significant. When diagnosing osteoporosis, T-scores in the interval −2.3 to −2.7 for spine or total hip (after rounding to conform to guidelines from the International Society for Clinical Densitometry) and −2.1 to −2.9 for femoral neck are not statistically different from −2.5. Better precision values resulted in smaller 95% CIs. This concept was applied to actual clinical data using Hologic DXA systems. The study cohort comprised 2388 white women with either normal or osteopenic spines in whom the densitometric diagnosis of osteoporosis would be determined by hip T-scores. When evaluating actual patient T-scores in the range −2.5 ± 95% CI, we found that the diagnosis was indeterminate in approximately 12% of women when T-scores for femoral neck were used and in 4% of women when T-scores for total hip were used, with uncertainty as to whether the classification was osteopenia or osteoporosis. We conclude that precision influences the variability around T-scores and that this variability affects the reliability of diagnostic classification.

Association Between the Female Athlete Triad and Endothelial Dysfunction in Dancers

To determine the prevalence of the 3 components of the female athlete triad [disordered eating, menstrual dysfunction, low bone mineral density (BMD)] and their relationships with brachial artery flow-mediated dilation in professional dancers. Prospective study. Academic institution in the Midwest. Twenty-two professional ballet dancers volunteered for this study. The prevalence of the female athlete triad and its relationship to endothelial dysfunction. Subjects completed questionnaires to assess disordered eating and menstrual status/history. They also completed a 3-day food record and wore an accelerometer for 3 days to determine energy availability. Serum baseline thyrotropin, prolactin, and hormonal concentrations were obtained. Bone mineral density and body composition were measured with a GE Lunar Prodigy dual-energy X-ray absorptiometry. Endothelial function was determined as flow-mediated vasodilation measured by high-frequency ultrasound in the brachial artery. An increase in brachial diameter <5% to hyperemic flow stimulus was defined a priori as endothelial dysfunction. Seventeen dancers (77%) had evidence of low/negative energy availability. Thirty-two percent had disordered eating (EDE-Q score). Thirty-six percent had menstrual dysfunction and 14% were currently using hormone contraception. Twenty-three percent had evidence of low bone density (Z-score < -1.0). Sixty-four percent had abnormal brachial artery flow-mediated dilation (<5%). Flow-mediated dilation values were significantly correlated with serum estrogen and whole-body and lumbar BMD. All the 3 components of the triad plus endothelial dysfunction were present in 14% of the subjects. Endothelial dysfunction was correlated with reduced BMD, menstrual dysfunction, and low serum estrogen. These findings may have profound implications for cardiovascular and bone health in professional women dancers.

Quantification of Bone Density of the Proximal Femur After Hip Resurfacing Arthroplasty—Comparison of Different DXA Acquisition Modes

Total hip arthroplasty (THA) is a traditional operative procedure in the treatment of osteoarthritis. The hip resurfacing arthroplasty (HRA) provides an alternative to the THA for young active patients. HRA is a bone-preserving procedure eliminating the problem of proximal femoral stress shielding and osteolysis associated to THA. Unfortunately, there is no standardized methodology to monitor the quality of bone after HRA. In this study, areal bone mineral density (BMD) in the operated hip (10 regions of interests [ROIs] of 34 volunteered HRA patients) was measured using Lunar Prodigy dual-energy X-ray absorptiometry, and the agreement of a standard (dual femur) and an orthopedic (orthopedic hip) acquisition modes was compared. Furthermore, reproducibility of the patient-specific analysis procedures was tested. The analysis procedures were reproducible with both acquisition modes (1.18%–1.37%). The mean (±standard deviation) difference between the acquisition modes was 1.46 ± 0.93%. At ROIs, a strong linear relationship was found between the results from 2 acquisition modes ( R 2 = 0.801–0.966, p < 0.01). In conclusion, both acquisition modes were reproducible, and it is suggested that the error induced by the different acquisition modes does not affect interpretation of BMD changes after HRA surgery.

Dietary Energy Density Affects Fat Mass in Early Adolescence and Is Not Modified by FTO Variants

BackgroundDietary energy density (DED) does not have a simple linear relationship to fat mass in children, which suggests that some children are more susceptible than others to the effects of DED. Children with the FTO (rs9939609) variant that increases the risk of obesity may have a higher susceptibility to the effects of DED because their internal appetite control system is compromised. We tested the relationship between DED and fat mass in early adolescence and its interaction with FTO variants.Methods and FindingsWe carried out a prospective analysis on 2,275 children enrolled in the Avon Longitudinal Study of Parents and Children (ALSPAC). Diet was assessed at age 10 y using 3-day diet diaries. DED (kJ/g) was calculated excluding drinks. Children were genotyped for the FTO (rs9939609) variant. Fat mass was estimated at age 13 y using the Lunar Prodigy Dual-energy X-ray Absorptiometry scanner. There was no evidence of interaction between DED at age 10 y and the high risk A allele of the FTO gene in relation to fat mass at age 13 y (β = 0.005, p = 0.51), suggesting that the FTO gene has no effect on the relation between DED at 10 y and fat mass at 13 y. When DED at 10 y and the A allele of FTO were in the same model they were independently related to fat mass at 13 y. Each A allele of FTO was associated with 0.35±0.13 kg more fat mass at 13 y and each 1 kJ/g DED at 10 y was associated with 0.16±0.06 kg more fat mass at age 13 y, after controlling for misreporting of energy intake, gender, puberty, overweight status at 10 y, maternal education, TV watching, and physical activity.ConclusionsThis study reveals the multi-factorial origin of obesity and indicates that although FTO may put some children at greater risk of obesity, encouraging a low dietary energy density may be an effective strategy to help all children avoid excessive fat gain.

Varying Ratios of Omega-6:Omega-3 Fatty Acids on the Pre-and Postmortem Bone Mineral Density, Bone Ash, and Bone Breaking Strength of Laying Chickens

The purpose of this study was to investigate the effects of varying ratios of n-6 to n-3 fatty acids in the diets of White Leghorn chickens on tibia bone characteristics [bone mineral density, bone mineral content (BMC), ash bone mineral content, bone morphology, and cortical thickness] and tibia bone strength parameters (ultimate force, bending stress, maximum strain, Young's modulus of elasticity, area under the curve, and moment of inertia). Seventy-five 16-wk-old female White Leghorn chickens were randomly assigned to 1 of 5 dietary ratios of n-6 to n-3 fatty acids: 47.8:1, 18.0:1, 7.6:1, 5.9:1, or 4.7:1. Corn oil was the n-6 fatty acid source, whereas flax oil provided the n-3 fatty acids. Bone density was measured on the left tibia via dual-energy x-ray absorptiometry (DXA) prior to killing and after excision. Bones were ashed in a muffle furnace at 500 degrees F. Tibia bones were broken by using a 3-point bending rig. Results showed no significant effect of diet on bone characteristics. There were no significant differences among diet groups for parameters of bone strength except cortical thickness (P < or = 0.01). Bone mineral content determined by ashing was significantly different by 9.2% (P < or = 0.0001) from BMC determined in vivo by DXA; however, there were no differences in ex vivo BMC and BMC ash, although they were highly correlated (r = 0.99, P < or = 0.0001). We concluded that there was no effect of n-3 fatty acids on tibia bone in mature White Leghorn chickens. The GE Lunar Prodigy DXA instrument significantly underestimated the in vivo BMC in chickens.

Normal Reference for Bone Density in Healthy Chinese Children

An ethnicity- and gender-specific normal reference database is necessary for the clinical dual-energy X-ray absorptiometry (DXA) assessment of skeletal status in Chinese children. We used a Lunar Prodigy DXA densitometer to measure bone mineral density (BMD), bone mineral content (BMC), and bone area (BA) at total body and subcranial skeleton for 877 healthy Chinese children (505 boys, 372 girls) aged 5–13 yr. The height-for-age, BA-for-height, and BMC-for-BA percentile curves were developed using the LMS method ( L, power in Box-Cox transformation; M, median; S, coefficient of variation). We found that total body BMD and subcranial skeleton BMD were highly correlated ( r = 0.701–0.949), and that total body BMD was significantly higher than subcranial skeleton BMD for each gender and age group ( p < 0.001). No gender differences in total body and subcranial skeleton BMD were found. Total body lean mass correlated highly with total body BMC and subcranial skeleton BMD and BMC (boys: r = 0.888–0.953, girls: r = 0.917–0.967) and moderately with total body BMD (boys: r = 0.684, girls: r = 0.777). The head region accounted for 16–52% and 16–49% of the total body BMC in boys and girls, respectively, and the percentages were negatively correlated with age (boys: r = −0.824, girls: r = −0.864) and height (boys: r = −0.911, girls: r = −0.922). Regression analyses showed that age explained more variance in subcranial skeleton BMD (boys: R 2 = 0.641, girls: R 2 = 0.685) than in total body BMD (boys: R 2 = 0.387, girls: R 2 = 0.472). In summary, we have presented an ethnicity- and gender-specific densitometric normal reference database for Chinese children aged 5–13 yr. It should allow for an appropriate clinical assessment of total body bone density in Chinese children as measured by the Lunar Prodigy DXA densitometer.

Effect of Precision Error on T-scores and the Diagnostic Classification of Bone Status

We quantified confidence intervals (CIs) for T-scores for the lumbar spine and hip and determined the practical effect (impact on diagnosis) of variability around the T-score cutpoint of −2.5. Using precision data from the literature for GE Lunar Prodigy dual-energy X-ray absorptiometry (DXA) systems, the 95% CI for the T-score was ±0.23 at the lumbar spine (L1–L4), ± 0.20 at the total hip, and ±0.41 at the femoral neck. Thus, T-score variations of ±0.23 or less at the spine, ±0.20 at the total hip, and ±0.41 at the femoral neck are not statistically significant. When diagnosing osteoporosis, T-scores in the interval −2.3 to −2.7 for spine or total hip (after rounding to conform to guidelines from the International Society for Clinical Densitometry) and −2.1 to −2.9 for femoral neck are not statistically different from −2.5. Better precision values resulted in smaller 95% CIs. This concept was applied to actual clinical data using Hologic DXA systems. The study cohort comprised 2388 white women with either normal or osteopenic spines in whom the densitometric diagnosis of osteoporosis would be determined by hip T-scores. When evaluating actual patient T-scores in the range −2.5 ± 95% CI, we found that the diagnosis was indeterminate in approximately 12% of women when T-scores for femoral neck were used and in 4% of women when T-scores for total hip were used, with uncertainty as to whether the classification was osteopenia or osteoporosis. We conclude that precision influences the variability around T-scores and that this variability affects the reliability of diagnostic classification.

Evaluation of Lunar Prodigy dual-energy X-ray absorptiometry for assessing body composition in healthy persons and patients by comparison with the criterion 4-component model

Dual-energy X-ray absorptiometry (DXA) is widely used to assess body composition in research and clinical practice. Several studies have evaluated its accuracy in healthy persons; however, little attention has been directed to the same issue in patients. The objective was to compare the accuracy of the Lunar Prodigy DXA for body-composition analysis with that of the reference 4-component (4C) model in healthy subjects and in patients with 1 of 3 disease states. A total of 215 subjects aged 5.0-21.3 y (n = 122 healthy nonobese subjects, n = 55 obese patients, n = 26 cystic fibrosis patients, and n = 12 patients with glycogen storage disease). Fat mass (FM), fat-free mass (FFM), and weight were measured by DXA and the 4C model. The accuracy of DXA-measured body-composition outcomes differed significantly between groups. Factors independently predicting bias in weight, FM, FFM, and percentage body fat in multivariate models included age, sex, size, and disease state. Biases in FFM were not mirrored by equivalent opposite biases in FM because of confounding biases in weight. The bias of DXA varies according to the sex, size, fatness, and disease state of the subjects, which indicates that DXA is unreliable for patient case-control studies and for longitudinal studies of persons who undergo significant changes in nutritional status between measurements. A single correction factor cannot adjust for inconsistent biases.