In 2008 the National Center for Health Statistics released a dualenergyx-rayabsorptiometry (DXA) whole body dataset from the NHANES population-based sample acquired with modern fan beam scanners in 15 counties across the United States from 1999 through 2004. The NHANES dataset was partitioned by gender and ethnicity and DXA whole body measures of %fat, fat mass/height 2 , lean mass/height 2 , appendicular lean mass/height 2 , %fat trunk/%fat legs ratio, trunk/limb fat mass ratio of fat, bone mineral content (BMC) and bone mineral density (BMD) were analyzed to provide reference values for subjects 8 to 85 years old. DXA reference values for adults were normalized to age; reference values for children included total and sub-total whole body results and were normalized to age, height, or lean mass. We developed an obesity classification scheme by using estabbody mass index (BMI) classification thresholds and prevalences in young adults to generate matching classification thresholds for Fat Mass Index (FMI; fat mass/height 2 ). These reference values should be
The method for determining body composition should be selected depending on research objectives. In general, methods have been developed with specific assumptions [2, 8, 9, 19] which limits is use to a certain group; such as males or females, general population or athletes, adults or children. At the organ and tissue level, imaging techniques such as computed axial tomography (CT) and multi-scan magnetic resonance imaging (MRI) are considered the “criterion” methods in assessing body composition [20, 21]. The image quality of CT is im- proving  but, compared to exposures of 2.5 mSv of typical natural environments, the effective radiation ex- posure is still ~10 mSv for a full body scan . MRI, al- though safe, requires a high technical proficiency and is not cost-effective. Dual-energyX-rayabsorptiometry (DXA) uses a relatively low dose of ionizing radiation (i.e., 1 mSv per scan) and is considered the safest and ap- propriate imaging modality to accesses body compos- ition . Still, the selection also needs to consider practical implications such as cost, operation, required technical skills, subject cooperation. Accessible, safe and cost-effective strategies are needed.
ABSTRACT - Precise body composition measurements are essential in animal nutrition studies because the impact of treatments is evaluated based on changes in body weight and composition. Various indirect techniques for animal compositional evaluation have been developed and evaluated for applicability in animal nutrition studies. A fast, accurate, minimally invasive method that requires little input is considered the ideal for providing information about the animal. Measurements obtained by dual-energyx-rayabsorptiometry (DXA) are highly correlated with those obtained by chemical analysis and dissection. The algorithms of DXA software partition the six chemical components of the body (lipids, water, proteins, carbohydrates, non-bone mineral, and bone mineral) into three compartments (total body mineral content, fat mass, and lean mass). Questions have been raised about how this partitioning affects the precision of the DXA method. In addition, the relationship between the DXA measurements and dissected carcass tissues is nonrepresentational of the relationship between DXA and chemical analysis. Furthermore, since DXA devices and their software were developed primarily for human medicine, they may not be fully adequate for animal evaluation. Calibration is required to obtain true values. The DXA method has some advantages and disadvantages that should be identiﬁed and controlled before calibration. Nonetheless, DXA is a valuable tool that provides precise, repeatable body composition measurements of live monogastric animals and their carcasses.
Evaluate the effect of the extract of Ginkgo biloba in the bone alkaline phosphatase, bone mineral density, in the mechanical properties of the tibia in rats with glucocorticoid-induced-osteoporosis. After osteoporosis induction, the rats were divided into five groups: Osteoporosis; EGb1 (28 mg/Kg); EGb2 (56 mg/Kg); alendronate (0.2 mg/animal) and control. The animals were treated during 20 and 30 days. The control group was compared with the osteoporosis’s (Student’s t-test), while the other were analyzed by ANOVA test followed by Tukey/Dunnett’T3 (p<0.05). In the osteoporosis group the bone alkaline phosphatase, bone mineral density, the bone stiffness, the maximum load and the resilience were reduced. The bone alkaline phosphatase values increased in the EGb1 and EGb2 groups (30 days). In addition, in the EGb2 and alendronate groups (20 and 30 days) the bone mineral density increased. The extract of Ginkgo biloba restored bone alkaline phosphatase and bone mineral density using dual-energyx-rayabsorptiometry. Key words: bone density, DEXA scan, Ginkgo biloba, osteoporosis.
The objective of the present study was to develope and to validate equations based on skinfold thickness for the estimation of percent body fat (%BF) in HIV/AIDS subjects using dualenergyX-rayabsorptiometry (DEXA) and computed tomography of abdomen (CTA) as the gold standards. The sample included 15 adult Brazilian HIV/AIDS subjects (10 men and 5 women). Mean age was 36.9 years (SD 8.2) and mean %BF by DEXA was 18.2 (SD 9.5). The estimation of %BF was done using linear regression models, and the independent variables were the sum of one to seven skinfold thickness. The skinfold thickness was compared with DEXA and CTA. The Durnin & Womersley equation was also tested. The best equation for males was [%BF = 3.385 + 0.279 * (axillary + subscapular); r2=0.83] and for females was [%BF = -24.323 + 0.736 * (suprailiac + abdominal + medial calf); r2=0.81]. The total error of the estimate of %BF in HIV/AIDS was <3.5%, the means were not different between males and females from the values measured by DEXA, and the estimated values were highly correlated with DEXA and CTA. The 95% limits of agreement between HIVE and DEXA by the Bland-Altman method were good. The Durnin & Womersley equation was also tested, and the values showed signifi cant differences in the means (males) and the total error was >3.5% for males and females in the comparison with DEXA. The HIV/AIDS equation complied with all the validation criteria. We recommended this equation to be tested in larger samples for estimating %BF among HIV/AIDS subjects. KEY-WORDS: body composition; HIV/AIDS; skinfold thickness; dualenergyX-rayabsorptiometry; computed tomography of abdomen.
A short-term precision error of the individual subject and the DEXA technique, such as the effect of the repositioning of the cat on the examination table, were established. Four neutered adult cats (BW=4342g) and three females (BW=3459g) were submitted to five repeated scans with and without repositioning between them. Precision was estimated from the mean of the five measurements and expressed by the individual coefficient of variation (CV). The precision error of the technique was estimated by the variance of scan pool (n=35) and expressed in CV for the technique (CVt). The degrees of freedom and confidence intervals were determined to avoid underestimation of precision errors. Bone mineral content (BMC), lean mass (LM), and fat mass (FM) averages were higher (P<0.05) when animals were repositioned. The CVt was significantly higher (P<0.05) for bone mineral density (BMD), LM, and FM when the animals were repositioned. For short-term precision measurements, the repositioning of the animal was important to establish the precision of the technique. The dualenergyx- rayabsorptiometry method provided precision for body composition measurements in adult cats.
The measurement of bone mineral density can be using by photon or X-ray. Single or dual photon and dual-energyX-rayabsorptiometry (DXA) images are two-dimensional (2D) pro- jection. These techniques convert pixel values to mineral area density (g/cm2) by using sotware. Although, quantitative com- puted tomograhy is three-dimensional (3D) projection of bone as a gold standard technique. It overcomes limitations of 2D projection. A majority of the previous studies to evaluate bone strength have measured primarily bone mineral density (BMD) relect bone material. Whereas, bone strength be impressed by both material and structural parameters. Therefore, to measure of BMD is inadequate to predict of fracture risk, which exceed- ing stress of bone strength. An important determinant of frac- ture risk is age-related changes in the structural geometry of bone tissue. New sotwares in bone density measurement, cal- culating femoral structural variables that can end hip fracture, have been developed. Cross-sectional bone mineral absorption curves were produced using single photon absorptiometry from Martin and et al.  Aterwards, this method has been altered for DXA called hip strength analysis (HSA) by some research- ers [9-11]. Femoral size, shape, and strength can easily assess with this program. The structural variables such as the cross- sectional area (CSA), femoral neck cross-sectional moment of inertia (CSMI), hip axis length (HAL), and femoral neck shat angle can be measured. Besides, the femur strength index (FSI), an amount of the ability of a hip to resist a fall on the greater trochanter, have been calculated union these parameters with age, height, and weight . Crabtree and et al suggested that HSA indicates substantially prospect as a means to enhance the diagnostic precision of predicting hip fracture .
The values for lean muscle mass and fat mass were assessed in the extremities by dualenergyX-rayabsorptiometry 15 (DXA). Body mass index, serum albumin, and serum levels of vitamins D and K were determined in all participants. For biochemical assays, blood samples were drawn in the morning after an overnight fast. Concentrations of 25-hydroxyvitamin D (25OHD) were determined by high-performance liquid chromatography (HPLC) on an Agilent 1100 HPLC system (Agilent Technologies Inc., Santa Clara, CA, USA). Plasma vitamin K concentrations were assessed by means of HPLC.
To estimate body fat mass (FM), fat free mass (FFM), percentage of fat (%FM), and fat trunk (FT), dual-energyx-rayabsorptiometry (DXA) measurements were made with a total body scanner (QDR-1500, pencil-beam mode, soft- ware version 5.67 enhanced whole-body analyses; Hologic, Waltham, MA, USA) that measured the attenuation of X-rays pulsed between 70 and 140 kV synchronously with the line frequency for each pixel of the scanned image. Following the protocol for DXA described by the manufacturer, a step phantom with six fields of acrylic and aluminum
Abstract Introduction: The aim of this study was to develop a speciic mathematical model to estimate the body fat percentage (BF%) of children with cerebral palsy, based on a Brazilian population of patients with this condition. Method: This is a descriptive cross-sectional study. The study included 63 Caucasian children with cerebral palsy, both males and females, aged between three and ten-years-old. Participants were assessed for functional motor impairment using the Gross Motor Function Classiication System (GMFCS), dualenergyx-rayabsorptiometry (DXA) and skinfold thickness. Total body mass (TBM) and skinfolds thickness from: triceps (Tr), biceps (Bi), Suprailiac (Si), medium thigh (Th), abdominal (Ab), medial calf (Ca) and subscapular (Se) were collected. Fat mass (FM) was estimated by dualenergyx-rayabsorptiometry (gold standard). Results: The model was built from multivariate linear regression; FM was set as a dependent variable and other anthropometric variables, age and sex, were set as independent variables. The inal model was established as F%=((0.433xTBM + 0.063xTh + 0.167xSi - 6.768) ÷ TBM) × 100, the R 2 value was 0.950, R 2
The authors performed a study of bone mass in eutrophic Brazilian children and adolescents using dual-energyX-rayabsorptiometry (DXA) in order to obtain curves for bone mineral content (BMC) and bone mineral density (BMD) by chronological age and correlate these values with weight and height. Healthy Caucasian children and ado- lescents, 120 boys and 135 girls, 6 to 14 years of age, residents of São Paulo, Brazil, were selected from the Pediatric Department outpatient clinic of Hospital São Paulo (Universidade Federal de São Paulo). BMC, BMD and the area of the vertebral body of the L2-L4 segment were obtained by DXA. BMC and BMD for the lumbar spine (L2-L4) presented a progressive increase between 6 and 14 years of age in both sexes, with a distribution that fitted an exponential curve. We identi- fied an increase of mineral content in female patients older than 11 years which was maintained until 13 years of age, when a new decrease in the velocity of bone mineralization occurred. Male pa- tients presented a period of accelerated bone mass gain after 11 years of age that was maintained until 14 years of age. At 14 years of age the mean BMD values for boys and girls were 0.984 and 1.017 g/cm 2 ,
ABSTRACT: The objective of this study was to evaluate the water intake, the chemical body composition, the residual feed intake and gain, and the nutritional requirements of energy and protein for maintenance and gain, and calcium and phosphorus requirements for maintenance as well as their efficiencies of Nellore bulls. Weaned Nellore bulls (n = 44; 273 ± 34 kg) were fed in a randomized complete block design 2 × 2 factorial arrangement to evaluate the nutritional requirements and water intake with absence or presence of mineral supplementation. The design included two levels of Ca and P (macro mineral factor; CaP+ or CaP-) and two levels of micro minerals (micro mineral factor; ZnMnCu+ or ZnMnCu-). The factor CaP- was without supplementation of limestone and dicalcium phosphate and the factor ZnMnCu- was without inorganic supplementation of micro minerals. The diets were isonitrogenous (13.3% CP). Intake was individually monitored every day. Indigestible NDF was used as an internal marker for digestibility measurements. A total of 44 Nellore bulls was used in this trial, where four animals were used as the reference group (harvested d 0); another four were fed at the maintenance level (1.1% of BW); and the remaining 36 were fed ad libitum. Bulls were blocked by days on fed, they were slaughtered on d 84 or 147, and samples of the whole body were taken. All samples were lyophilized, ground with liquid nitrogen and grouped as percentage of component in empty BW from each bull. Samples were analyzed for DM, ash, CP, EE, Ca, and P. The water intake was similar (P ≥ 0.07) among treatments. The average of free water intake
A DEXA utiliza uma fonte de raios x com um filtro que converte o feixe de raios em picos fotoelétricos de baixa e alta energia. Este feixe atravessa o corpo e é detectada a atenuação provocada pelos diferentes tecidos. As propriedades de atenuação da gordura e dos tecidos magros foram estabelecidas a partir de fantomas. Considerando-se que a atenuação é uma função da proporção de gordura e de tecido magro, a partir dos valores obtidos podemos inferir a quantidade de gordura e de tecido magro em cada pixel avaliado. Essa técnica baseia-se em três pressupostos: a gordura e o tecido magro isento de osso estão associados a uma atenuação dos raios x diferente; a espessura ântero-posterior não influencia os valores obtidos e a área avaliada é representativa de toda a área corporal, considerando-se que cada região do corpo é em termos de volume. 1
The aim of this study was to evaluate the effects of castration on bones in the male guinea pigs and to observe whether mechanical testing correlates with dual-energyX-rayabsorptiometry (DXA). Twelve male guinea pigs (Cavia porcellus), aged 21-27 days, and with average initial weight of 279 grams were used. The animals were equally allocated to two groups: GI - orchiectomized animals and GII - intact control animals. They underwent euthanasia at seven months following surgery. DXA measurement was performed at the mid- third of the right femoral diaphysis in the cortical region and at the left femoral neck in order to verify its correlation with results of mechanical testing. Three-point bending test of right femur and axial compression test of left femur were performed. Bone mineral density of GI was significantly lower only at femoral neck. No differences were observed in the maximum load values between GI and GII for both bending and axial compression tests. The bending test revealed lower bone stiffness in GI compared to GII, but in the axial compression test no differences between groups were observed. Only left femur showed positive correlation coefficient between maximum load and bone mineral density according to Pearson's correlation coefficient. The results suggest that hormonal deprivation in guinea pigs induces reduction of bone mineral density, especially in the femoral neck area and reduction of bone stiffness in the mid-femoral diaphysis.
Van der Sluis IM, de Ridder MA, Boot AM, Krenning EP, Muinck Keizer-Schrama SM. Reference data for bone density and body composition measured with dualenergyxrayabsorptiometry in white children and young adults. Arch Dis Child 2002; 87(4):341-347. Santos GPC, Domingos MT, Witting EO, Riedi CA, Ro- sario NA. Programa de triagem neonatal para fibrose cística no estado do Paraná: avaliação após 30 meses de sua implantação. J Pediatr (Rio J) 2005; 81(3):240-244. Ludwig Neto N. Fibrose Cística Enfoque Multidiscipli- nar. 2ª ed. Florianópolis: Secretaria de Estado da Saúde de Santa Catarina; 2009. Disponível em: http://acam. org.br/livro-fibrose-cistica-enfoque-multidisciplinar Cabello GMK. Avanços da Genética na Fibrose Cís- tica. Rev Hospital Universitário Pedro Ernesto 2011; 10(4):36-45.
An ultrasound of the abdominal region is a practical, reliable and economic technique to diagnose NAFLD , and, additionally, allows the measurement of intra- abdominal fat thickness . Besides, the central adiposity can be estimatedby other methods, such as the dual-energyX-rayabsorptiometry (DEXA)  which presents high correlation with intra-abdominal adipose tissue (IAAT) and can be used as indicator of metabolic diseases,