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1.
Chauhan S Koo WW Hammami M Hockman EM 《Journal of the American College of Nutrition》2003,22(5):408-414
OBJECTIVES: A piglet model was used to validate and cross validate the fan-beam (FB) dual energy X-ray absorptiometry (DXA) software vKH6 and to determine the predictive values of physiologic parameters (weight, length, age and gender) on body composition. METHODS: Nineteen piglets (Group A: 600 to 21100 g) were used to validate the FB-DXA measurements of body composition based on chemical analysis of the carcass. An additional 22 piglets (Group B: 640 g to 17660 g) had FB-DXA measurements, and these values were compared to the predicted values generated from regression equations computed from group A piglets. Body composition for bone mass, lean mass and fat mass was based on ash weight, nitrogen and fat measured from three aliquots of homogenate from each carcass. Data from all piglets (n = 41) were used to determine the variations in body composition. Data analysis used regression, t test and analysis of variance. RESULTS: Duplicate DXA (total weight TW, bone mineral content BMC, bone area BA, bone mineral density BMD, lean mass LM and fat mass FM) measurements were highly correlated (r = 0.98 to 1.00, p < 0.001 for all comparisons) and were not significantly different. No significant differences were found in the residuals from predicted versus measured DXA values between the larger and the smaller (<1.6 kg) piglets from Group A. For Group B piglets, the DXA measured TW of 5666 +/- 5692 g (mean +/- SD), LM (5063 +/- 5048 g), FM (465 +/- 510 g), BMC (138 +/- 139 g), BA (486 +/- 365 cm(2)) and BMD (0.235 +/- 0.071 g/cm(2)) were highly significantly correlated with (r = 0.94 to 1.00, p < 0.001 for all comparisons) and were not significantly different from the predicted values. Data from all piglets (n = 41) showed that weight is the dominant predictor of whole body and regional body composition. Length, age or gender contributed to <2% of the variability of body composition. CONCLUSION: Body composition measurements using the FB DXA software vKH6 is highly reproducible. The software vKH6 is validated for use in a wide range of body weights and body composition, and cross-validated using a separate group of animals. Body weight is the dominant predictor of body composition in immature piglets. 相似文献
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A piglet model was used to determine whether the fan beam dual energy X-ray absorptiometry technique (DXA) could be adapted for the measurement of body composition of small subjects. Commercial domestic swine piglets (n = 14) with weights between 1.95 and 21.1 kg had duplicate fan beam-DXA scans followed by chemical analysis of body composition. Each scan required 2-3 min to complete. DXA-measured total body weight was validated against scale weights of the piglets (with and without blanket and other covering), DXA bone mineral content validated against carcass ash and calcium, and DXA lean and fat mass validated against chemical lean and fat contents. Measurements from duplicate DXA scans were highly reproducible with adjusted r(2) values from 0.992 to 1.000. Each DXA measurement was highly predictive of the scale weight or specific chemical body composition with adjusted r(2) values from 0.974 to 0.999. The intraclass reliability coefficient among measurements from individual scans with scale weight or the weight of individual chemical components was extremely high at > or =0.99 for all comparisons. The SD of residuals for DXA prediction of scale weights (with and without covering) were 168 and 157 g, respectively, and were 27, 8.8, 122 and 72 g for the prediction of carcass ash, calcium, lean and fat tissue content, respectively. We conclude that rapid scan acquisition, accurate and precise prediction of scale weight and components of body composition would support the use of fan beam-DXA for body composition studies in growing humans or animals. 相似文献
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OBJECTIVE: To validate the most widely reported dual energy X-ray absorptiometry (DXA) technique for the measurement of bone mass and body composition in human infants with a piglet model. METHODS: Duplicate scans were obtained in 13 piglets (1950g to 21100g) using a whole body densitometer (Hologic QDR 2000 plus, Hologic Inc., Waltham, MA) operated in the pencil-beam mode on a two platform (aluminum platform overlying a foam table pad) system. DXA measurements that included total weight, bone mineral content, fat and lean mass were compared with carcass weight and chemical analysis for ash and calcium content, fat and lean mass. RESULTS: Measurements from duplicate DXA scans were nearly perfectly correlated (r = 0.98 to 1.00). DXA measurements were strongly predictive of scale weight and chemical composition for all piglets (adjusted r(2) = 0.93 to 1.00, intraclass reliability coefficients = 0.943 to 0.999, p < 0.001 for all comparisons) although DXA bone mineral content consistently underestimated carcass ash and calcium content. Measured values from heavier piglets were not significantly different from values predicted from the lighter piglets' data. Slopes from regression based on lighter versus heavier piglets were not significantly different except for the bone mineral content with carcass ash or calcium content. CONCLUSION: Our study validated the use of pencil beam DXA and its ability to determine relative changes in bone mass and body composition measurements over a much greater range of body weight than previous reports although its use as a direct indicator of nutrient requirement may be limited. 相似文献
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Koo WW Hammami M Shypailo RJ Ellis KJ 《Journal of the American College of Nutrition》2004,23(6):647-650
OBJECTIVES: A piglet model was used to determine the variations in measurements from different software algorithms used in the same type of dual energy X ray absorptiometry (DXA) instruments from the same manufacturer. METHODS: Forty-one piglets (6190 +/- 5856g, mean +/- SD) were scanned in duplicate with a fan-beam densitometer (Hologic QDR4500A, Hologic Inc, Bedford, MA) in the infant whole body scan mode. The same scans were analyzed with two software versions: vKH6 (validated with carcass chemical measurement) and v11.2 (commercial software from the same densitometer manufacturer). RESULTS: All analysis values were highly correlated (r = 0.90 to 1.00) and DXA values for total weights were almost identical. However, v11.2 results consistently overestimated bone mineral content (49.3 +/- 23.4%, mean +/- SD), bone area (21.1 +/- 8.2%), bone mineral density (24.1 +/- 22.2%), and fat mass (160.9 +/- 71.7%) but underestimated lean mass (-14.3 +/- 5.5%) when compared to the values from vKH6. Differences between software versions increased with heavier piglets. CONCLUSION: The commercial software for fan-beam DXA measurement of piglets, matched for the size of human infants and young children, has major inaccuracies for bone mineral and body composition that become further exaggerated with increasing weight of the subject. 相似文献
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《Early child development and care》2012,182(3):475-485
Objective: The main aim was to examine the association between fundamental movement skills (FMS) and objectively measured body composition using dual energy X-ray absorptiometry (DXA). Methods: A study of 304 eight-year-old children in Finland. FMS were assessed with the Test of gross motor development, 2nd ed. Total body fat percentage (BF%), abdominal region fat percentage (AF%) and fat-free mass (FFM) were assessed by DXA. Waist circumference, height and weight were measured, and International Obesity Task Force cut-off values for body mass index were used for the definition of healthy weight and overweight/obesity. Results: Better FMS proficiency (object control, locomotor and total FMS) was significantly and strongly associated with lower BF% and lower AF% measured with DXA. Conclusions: The inverse association between FMS and body composition measured with DXA (BF% and AF%) is an important finding, as body fatness and specifically abdominal fatness are associated with less favourable cardiovascular risk factor status in children. 相似文献
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Hammami M Picaud JC Fusch C Hockman EM Rigo J Koo WW 《Journal of the American College of Nutrition》2002,21(4):328-332
OBJECTIVE: To test the suitability of phantoms to cross-calibrate body composition measurements in small subjects among different dual energy X-ray absorptiometry (DXA) instruments. METHODS: A set of four phantoms with total weights 1520g, 3140g, 4650g and 7490g were made with low cost and easily available materials. Each phantom was made from assembling polyethylene bottles (100 to 1000 mL) filled with either pure olive oil or electrolyte solution in different combinations, and borosilicate tubes (3 and 5 mL) and flexible polypropylene tubing filled with calcium carbonate. Triplicate measurements of each of the four phantoms were performed with three pencil beam densitometers made by the same manufacturer (Hologic Inc., Waltham, MA): two QDR 2000 (University of Liege, Liege, Belgium, and Wayne State University, Detroit, Michigan) and a QDR1500 (University Children's Hospital, Greifswald, Germany) using infant whole body-scanning mode and analyzed with software V5.73P. RESULTS: DXA measured total weight, or bone, lean and fat masses, from one center were highly predictive of DXA measurements from the other centers with an adjusted r2 of 0.94 to 1.00, p < 0.001. This was the case whether the measurements from single scan or from average of triplicate scans were used in the analysis. CONCLUSIONS: Systematic corrections, in the form of linear transformations, are possible to allow comparison of clinical data generated from different centers. Different size phantoms can be made to accommodate the varying range of weights and body composition of study subjects. 相似文献
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To quantify the appendicular and axial bone mineral with good accuracy and precision, dual energy X-ray absorptiometry (DEXA), DCS-600 (Aloka) for the radius, mainly composed of cortical bone, and QDR-1000 (Hologic) for the lumbar vertebrae, mainly composed of trabecular bone, was used. Bone loss with aging was earlier in females than that in males, and it was also more prominent in the lumbar vertebrae than that in the radius. Furthermore, the vertebral fracture rate could be evaluated by calculating percentile of an individual bone mineral density to the peak bone mass. Thus, the bone mineral determination using DEXA in both the appendicular and axial bone will provide a useful information in the assessment of bone loss, and the detection of the patients with high risk of fracture in osteoporosis. 相似文献
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This article forms part of our 'Tests and results' series for 2011 which aims to provide information about common tests that general practitioners order regularly. It considers areas such as indications, what to tell the patient, what the test can and cannot tell you, and interpretation of results. Dual energy X-ray absorptiometry (DXA) is the gold standard for diagnosing osteoporosis (OP). It uses X-rays at two energy levels and works on the principle that, as X-rays pass through body tissues they are attenuated to a different extent in different tissue types. The result - the bone mineral density (BMD) - can be reported at a number of sites. The most clinically useful are the lumbar spine, femoral neck and total hip (also termed the 'proximal femur'). 相似文献
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目的:探讨围绝经期妇女年龄、月经情况、身高、体重与骨密度(BMD)的关系,筛选绝经后骨质疏松症的高危人群。方法:随机选取148例2004年9~11月青岛市部分金融系统女职员健康查体中的围绝经期(40~60岁)妇女,加查双能X线BMD(已筛除影响骨代谢性疾病如糖尿病、甲亢等及药物因素,如性激素补充),将BMD测定结果与其年龄、月经情况、体重、身高进行相关分析。结果:148例围绝经期妇女平均腰椎低骨量发生率为26.35%。50~60岁妇女腰椎低骨量发生率为48.44%,明显高于40~50岁妇女(9.52%);绝经者腰椎低骨量发生率为61.70%,明显高于未绝经者(9.90%);体重低于60kg者腰椎低骨量发生率为36.92%,高于体重在60kg以上者(18.07%);身高在160cm以下者腰椎低骨量发生率为44.12%,高于身高在160cm以上者(21.05%),其差异均有统计学意义;年龄、绝经与否、身高、体重与左髋部BMDt值无相关性。结论:围绝经期妇女腰椎低骨量发生率与绝经、年龄及其身高体重有关,绝经、年龄50岁以上、体重60kg以下、身高160cm以下的妇女是发生绝经后骨质疏松症的高危人群。 相似文献
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Bott L Béghin L Gondon E Hankard R Pierrat V Gottrand F 《Clinical nutrition (Edinburgh, Scotland)》2006,25(5):810-815
Since children with bronchopulmonary dysplasia often suffer from malnutrition and growth failure, evaluation of body composition is a very important tool to nutritional support. The aim of this study was to compare assessment of fat-mass (FM) and fat-free mass (FFM), evaluated by bio-impedancemetry and anthropometry compared to dual-X-ray-absorptiometry (DXA) in children with bronchopulmonary dysplasia. PATIENTS: Seventy-one children, aged 4-8 years, with bronchopulmonary dysplasia were enrolled. METHODS: FM and FFM measured using anthropometry and bio-impedancemetry were compared to FM and FFM obtained by DXA using the Bland-Altman method. RESULTS: Both bio-impedancemetry and anthropometry gave good agreement with DXA to evaluate FM and FFM. Anthropometry method, in general, slightly under-estimated FM (mean difference: -0.02 kg, standard deviation: 0.99) and FFM (mean difference: -0.70 kg+/-1.72). Bio-impedancemetry method overestimated FM (mean difference: 0.34 kg+/-2.06) and underestimated FFM (mean difference: -1.24 kg+/-3.32). CONCLUSION: In children with bronchopulmonary dysplasia aged, 4-8 years, both anthropometry and bio-impedancemetry cannot be used to precisely evaluate body composition. 相似文献
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Claude Pichard MD Ursula G. Kyle MS RD Jean-Paul Janssens MD Luc Burdet MD Thierry Rochat MD Daniel Olivier Slosman MD Jean-William Fitting MD Daniel Thiebaud MD Michel Roulet MD Jean-Marie Tschopp MD Michel Landry MD Yves Schutz PHD 《Nutrition (Burbank, Los Angeles County, Calif.)》1997,13(11-12)
Nutrition assessment is important during chronic respiratory insufficiency to evaluate the level of malnutrition or obesity and should include body composition measurements. The appreciation of fat-free and fat reserves in patients with chronic respiratory insufficiency can aid in designing an adapted nutritional support, e.g., nutritional support in malnutrition and food restriction in obesity. The purpose of the present study was to cross-validate fat-free and fat mass obtained by various bioelectric impedance (BIA) formulas with the fat-free and fat mass measured by dual-energy X-ray absorptiometry (DXA) and determine the formulas that are best suited to predict the fat-free and fat mass for a group of patients with severe chronic respiratory insufficiency. Seventy-five patients (15 women and 60 men) with chronic obstructive and restrictive respiratory insufficiency aged 45–86 y were included in this study. Body composition was calculated according to 13 different BIA formulas for women and 12 for men and compared with DXA. Because of the variability, calculated as 2 standard deviations, of ± 5.0 kg fat-free mass for women and ± 6.4 kg for men for the best predictive formula, the use of the various existing BIA formulas was considered not clinically relevant. Therefore disease-specific formulas for patients with chronic respiratory insufficiency should be developed to improve the prediction of fat-free and fat mass by BIA in these patients. 相似文献
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Plank LD 《Current opinion in clinical nutrition and metabolic care》2005,8(3):305-309
PURPOSE OF REVIEW: Dual-energy X-ray absorptiometry is now widely adopted for the measurement of the fat, fat-free soft tissue and bone mineral compartments of the body. Whereas it is regarded by many as a reference technique for such measurements, it is not without limitations. Inter and intra-manufacturer differences have been areas of concern. This review focuses on recent literature addressing these areas and the issue of validity. RECENT FINDINGS: Body composition measurements using newer generation dual-energy X-ray absorptiometry machines compared between different manufacturers and compared with earlier instruments continue to show differences that may be unacceptable, particularly for investigators upgrading their machines or involved in multicentre studies using different machines. In terms of validity, significant deviations at a group level are reported when compared with reference four-component models, and perhaps more importantly, wide limits of agreement are seen that are a concern for the interpretation of results at an individual level. SUMMARY: It is important that investigators recognize the limitations of dual-energy X-ray absorptiometry technology in the interpretation of their results. There is a continuing need both for inter-machine comparisons and validation studies against accepted criterion methods, particularly as new software or technological changes are introduced. Such studies permit the development of translation equations for the cross-calibration of devices, and may be vital for cross-sectional studies. For longitudinal studies in many populations, dual-energy X-ray absorptiometry is without question a valuable technique for the measurement of compositional changes, both at the total body and regional levels. 相似文献
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BACKGROUND: There is an interest in noninvasive measurement of body fat in newborns and infants. Measurement of skinfold thickness (SFT) is a simple clinical method. OBJECTIVE: We correlated fat mass (FM) values of neonates and infants predicted from SFT measurements and compared them with FM values measured by dual-energy X-ray absorptiometry (DXA), a validated in vivo method for determining body fat. DESIGN: The weight, length, body composition (DXA measurement of FM and percentage of body fat), and SFT of 104 healthy term and preterm infants were measured at 0, 2, and 4 mo of age. RESULTS: Mean (+/- SD) FM determined by DXA increased from 440 +/- 220 g at birth to 1310 +/- 450 g at 2 mo of age and to 2170 +/- 605 g at 4 mo of age. The percentage of body fat increased from 13.3% at birth to 24.5% and 31.2% at 2 and 4 mo of age, respectively. An equation was developed to calculate FM (in g) in newborns by using the sum of SFT measurements (in mm) and body length (l; in cm): FM = 68.2 x SigmaSFT((0.0162) x l) - 172.8 (R(2) = 0.948, P < 0.001). CONCLUSIONS: With the use of statistical bootstrap analysis, the results provide an in vivo validation of SFT measurements against DXA for newborns and young infants. Body fat measurements by SFT correlate with FM values determined by DXA (R(2) = 0.936). Estimation of nutritional status is possible with errors (SD) of +/- 75, +/- 170, +/- 300, and +/- 380 g for infants with an FM 2000 g, respectively. 相似文献
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Haderslev KV Jeppesen PB Sorensen HA Mortensen PB Staun M 《The American journal of clinical nutrition》2003,78(1):78-83
BACKGROUND: Patients who have undergone resection of the small intestine have lower body weight than do healthy persons. It remains unclear whether it is the body fat mass or the lean tissue mass that is reduced. OBJECTIVE: We compared body-composition values in patients who had undergone small-intestinal resection with reference values obtained in healthy volunteers, and we studied the relation between body-composition estimates and the net intestinal absorption of energy. DESIGN: In a cross-sectional study, we included 20 men and 24 women who had undergone small-intestinal resection and had malabsorption of energy > 2000 kJ/d. Diagnoses were Crohn disease (n = 37) and other conditions (n = 7). Body composition was estimated by dual-energy X-ray absorptiometry, and data were compared with those from a reference group of 173 healthy volunteers. Energy absorption was measured during 48-h balance studies by using bomb calorimetry, and individual values were expressed relative to the basal metabolic rate. RESULTS: Body weight and body mass index in patients were significantly (P < 0.05) lower than the reference values. Fat mass was 6.4 kg (30%) lower (95% CI: -8.8, -3.9 kg), but lean tissue mass was only slightly and insignificantly lower (1.5 kg, or 3.3%; 95% CI: -3.7, 0.60 kg). Weight, body mass index, and body-composition estimates by dual-energy X-ray absorptiometry did not correlate significantly with the net energy absorption relative to the basal metabolic rate, expressed as a percentage. CONCLUSIONS: Patients who had undergone small-intestinal resection had significantly lower body weights and body mass indexes than did healthy persons, and they had significant changes in body composition, mainly decreased body fat mass. 相似文献
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Genton L Karsegard VL Zawadynski S Kyle UG Pichard C Golay A Hans DB 《Clinical nutrition (Edinburgh, Scotland)》2006,25(3):428-437
BACKGROUND AND AIMS: Weight measured by dual-energy X-ray (DXA) was shown to be increasingly underestimated in subjects over 75 kg compared to an electronic scale. This study compares body weight and composition measured by balance beam scale and three DXA acquisition modes in obese subjects. METHODS: In 39 obese, body weight was measured by balance beam scale, and body weight and composition by DXA Hologic QDR4500A in normal (NPM) and high power mode (HPM) (Enhanced v8.26 and v8.26* software) and DXA GE-Lunar Prodigy (v6.5 software). To ensure linearity of body weight and composition measured by the different DXA acquisitions, we also measured 13 women with a body mass index (BMI) of 25-30 kg/m(2). RESULTS: While QDR4500A HPM overestimates scale weight by about 2 kg over the whole BMI spectrum, QDR4500A NPM underestimates scale weight as a weight-dependent response (-1.7+/-1.8 kg overall, -4.1+/-1.6 kg in morbidly obese women). These results suggest switching from one mode to the other at a specific threshold, i.e. in our study a weight of 90 kg or a BMI of 34 kg/m(2). Prodigy gives weight about similar to scale (+0.5+/-0.8 kg). Both Hologic acquisition modes underestimate fat mass but overestimate lean body mass compared to Prodigy. CONCLUSIONS: The QDR4500A NPM is inappropriate in women over 90 kg. Unfortunately, the QDR4500A HPM overestimates body weight in the range of 90-150 kg. The difference between scale and Prodigy weight remains stable throughout weight ranges. To better assess their accuracies in terms of body composition, QDR4500A NPM, HPM and Prodigy should be tested against phantoms or in vivo multi-compartment models. 相似文献
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Rodríguez G Moreno LA Blay MG Blay VA Fleta J Sarría A Bueno M;AVENA-Zaragoza Study Group 《European journal of clinical nutrition》2005,59(10):1158-1166
OBJECTIVE: To compare the most commonly used equations to predict body fatness from skinfold thickness, in male and female adolescents, with dual-energy X-ray absorptiometry (DXA) as a reference method of fatness measurement. DESIGN: Cross-sectional nutrition survey. SETTING: General adolescent population from Zaragoza (Spain). SUBJECTS AND METHODS: A total of 238 Caucasian adolescents (167 females and 113 males), aged 13.0-17.9 y, were recruited from 15 school groups in 11 public and private schools. The percentage fat mass (%FM) was calculated by using skinfold-thickness equations. Predicted %FM was compared with the reference %FM values, measured by DXA. The lack of agreement between methods was assessed by calculating the bias and its 95% limits of agreement. RESULTS: Most equations did not demonstrate good agreement compared with DXA. However, in male adolescents, Slaughter et al equations showed relative biases that were not dependent on body fatness and the limits of agreement were narrower than those obtained from the rest of equations. In females, Brook's equation showed nonsignificant differences against DXA and the narrowest 95% limits of agreement. Only biases from Brook and Slaughter et al equations were not dependent on body fatness in female adolescents. CONCLUSIONS: Accuracy of most of the skinfold-thickness equations for assessment of %FM in adolescents was poor at the individual level. Nevertheless, to predict %FM when a relative index of fatness is required in field or clinical studies, Slaughter et al equations may be used in adolescents from both sexes and the Brook equation in female adolescents. 相似文献