DEXA analysis was achieved using a QDR-4500A densitometer (Hologic Inc., Waltham, MA, USA) with a module for small animal measurements. The software identifies and estimates global lean mass (g), global fat mass (g), global percentage of fat (%), global mass (g). Rats were anesthetized with an inhalational anaesthesia with 1.5–3 Vol% isoflurane (Forene® 100% (V/V), Abbott, Wiesbaden, Germany) at maintenance, terminated after 40 minutes. After anesthesia, rats were positioned ventrally. Five repeated measurements were performed.
Qdr 4500a densitometer
Manufactured by Hologic
Sourced in United States
The QDR-4500A densitometer is a medical device used to measure bone density. It employs x-ray technology to assess the mineral content of bones, providing data that can be used to diagnose and monitor conditions such as osteoporosis.
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Lab products found in correlation
Ge light speed 1.1 ct scanner, by GE Healthcare (3 mentions)
Whole body fan beam software v8.269 3, by Hologic (2 mentions)
Forene 100 5 5, by Abbott (1 mentions)
Xct 3000, by Stratec (1 mentions)
Qdr 4500a, by Hologic (1 mentions)
Light speed 1.1 ct scanner, by GE Healthcare (1 mentions)
Discovery software, by Hologic (1 mentions)
12 protocols using qdr 4500a densitometer
1
DEXA Analysis of Body Composition in Rats
2
Measurement of Bone Density in YFHI Study
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In the YFHI study, participants had their BMD at the total body, lumbar spine, and hip measured at the Royal Melbourne Hospital using dual-energy x-ray absorptiometry (DXA) (QDR 4500A densitometer, Hologic Inc). Participants who had relatively low (z score ≤–0.5 at the total hip, femoral neck, or lumbar) or otherwise abnormal (z score <–1.0) bone density results were informed via postal letter including advice on appropriate follow-up. A copy of the participant’s BMD report was enclosed with the letter. Participants were advised to discuss the result and any necessary further management with their usual doctor. Only participants who met the bone density cutoff values specified below were contacted for this study.
3
Dual-Energy X-Ray Absorptiometry in BMD Assessment
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BMD was measured using dual energy X-ray absorptiometry operating in fan-beam mode (Hologic QDR 4500A densitometer, Hologic Inc., Waltham, MA, USA). Quality control scans were carried out daily, using the manufacturer-supplied anthropomorphometric spine phantom; the long-term (>1 year) coefficient of variation was 0.40%. Lumbar BMD was assessed from L2 to L4, in the postero-anterior view incidence, and fractured vertebrae were excluded from the analysis. Total hip BMD and femoral neck BMD were measured at upper left femur. The mean precision error of dual energy X-ray absorptiometry measurement is <1.5% for the lumbar spine and <2% for hip BMD. As usually, the results were expressed in absolute values (g/cm2) and using the T-score. The T-scores were calculated using manufacturer's references and expressed the difference between the subject value and the mean value of healthy young adults. The World Health Organization has defined normal BMD as a T-score >−1, low bone density as a T-score between −2.5 and −1, and osteoporosis as a T-score <−2.5.
4
Body Composition and Adipose Tissue Evaluation
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Before surgery, patients underwent a dual-energy X-ray absorptiometry exam (Hologic QDR-4500A densitometer with whole-body fan beam software v8.26a:3-Hologic) to assess body composition. Subjects also underwent a CT exam (GE Light Speed1.1 CT scanner, General Electric Medical Systems) to assess abdominal SC and visceral adipose tissue cross-sectional area measurements at the L4L5 vertebrae level.24 (link)
5
Comprehensive Bone Density Assessment
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Areal BMD is measured using dual energy X-ray absorptiometry (DXA) (QDR 4500A densitometer, Hologic Inc., Bedford, USA). Scans are analysed with QDR software version 9.1D. Areal BMD and bone mineral content (BMC) are measured at the lumbar spine (L1-L4), total hip and total body. Non-bone lean mass (kg), fat mass (kg) and percent body fat are also assessed. Peripheral quantitative computed tomography (pQCT) (XCT 3000, Stratec Medizintechnik GmbH, Pforzheim, Germany) is performed at the distal tibia (at the 4% site of the tibial length proximal to the distal end plate) and at the tibial shaft (at the 66% site) of the non-dominant leg. Scans are analysed with software version 5.50 to assess bone parameters including BMC, volumetric BMD, total bone area (toA), cortical area (coA), cortical thickness (coTh), polar stress-strain index (SSIp) and bone strength index (BSI). Muscle cross-sectional area (MCSA) is also measured.
6
Body Composition and Adipose Tissue Analysis
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These measurements were performed on the morning of or a few days before surgery. Body composition was assessed by dual-energy x-ray absorptiometry using a Hologic QDR-4500A densitometer and the whole-body software body fan V8.269:3 (Hologic Inc., Bedford, MA, USA). Measurement of abdominal subcutaneous and visceral adipose tissue cross-sectional areas at the L4-L5 vertebrae was performed by computed tomography as previously described [32 (link), 33 (link)].
7
DXA-Based Sarcopenia Assessment Protocol
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DXA has been widely used to assess sarcopenia. DXA measures the lean mass of whole body, including the trunk and four limbs, of which skeletal muscle is the largest component. DXA scans were conducted on individuals of 8 years and older who were not pregnant. Participants of body height over 196 cm and body weight over 136 kg were excluded for DXA examination. Whole body DXA scans were obtained by using a QDR 4500A densitometer (Hologic, Inc., Bedford, MA). It has been found by Schoeller et al. that the QDR 4500A Hologic densitometers underestimate fat mass in adults; thus, in NHANES surveys the fat mass and lean soft tissue mass were calibrated without affecting total mass [11, 19] . All scans were sent to the University of California, San Francisco, for further process with standard protocols.
Appendicular lean mass (ALM) was calculated by summing up lean tissues (excluding bone) of the four limbs. The criteria for ALM-defined sarcopenia were partially adopted from the Foundation for the National Institutes of Health (FNIH) as ALM divided by BMI, and sarcopenia was defined as a binary variable if ALM/BMI is less than 0.789 for male and less than 0.512 for female [20] (link). Multiple imputations were carried out in our analyses to deal with missing data strictly followed by the NHANES analytical guidelines [19, 21] (link).
Appendicular lean mass (ALM) was calculated by summing up lean tissues (excluding bone) of the four limbs. The criteria for ALM-defined sarcopenia were partially adopted from the Foundation for the National Institutes of Health (FNIH) as ALM divided by BMI, and sarcopenia was defined as a binary variable if ALM/BMI is less than 0.789 for male and less than 0.512 for female [20] (link). Multiple imputations were carried out in our analyses to deal with missing data strictly followed by the NHANES analytical guidelines [19, 21] (link).
8
Quantifying Body Composition Using CT and DXA
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These data were collected a few days prior to or on the morning of surgery. Dual-energy x-ray absorptiometry was performed with a Hologic QDR-4500A densitometer and the Whole-body fan beam software V8.269:3 (Hologic, Bedford, MA) was used to measure total body fat mass, fat percentage and lean body mass. Visceral and subcutaneous adipose tissue cross-sectional areas were measured by computed tomography with a GE Light Speed 1.1 CT scanner (General Electric Medical Systems, Milwaukee, WI). To perform the test, women had to lie in the supine position, their arms stretched above the head. To determine scanning position, a scout image of the body was used and images were obtained at the level of the L4-L5 vertebrae. To obtain visceral adipose tissue area, the intra-abdominal cavity was delineated using the ImageJ 1.33u software (National Institutes of Health, Bethesda, MD) at the internalmost aspect of the abdominal and oblique muscle walls around the cavity as well as the posterior aspect of the vertebral body. The area of subcutaneous adipose tissue was then calculated by subtraction of measured visceral adipose tissue area from total adipose tissue area at L4-L5. Highlighting and computation of adipose tissue areas were performed within the attenuation range of -190 to -30 Hounsfield units. All images were analyzed by the same observer.
9
Measuring Body Composition before Surgery
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On the morning of or a few days before surgery, body weight, height, body mass index (BMI) and waist circumference were measured. Participants also underwent a computed tomography (CT) exam (GE Light Speed 1.1 CT scanner, General Electric Medical Systems, Milwaukee, WI) at the L4L5 levels to assess visceral and abdominal subcutaneous (SC) adipose tissue areas as previously described (20) . Total body fat mass and lean body fat mass were assessed by dual-energy X-ray absorptiometry (DXA) (Hologic QDR-4500A densitometer with whole-body fan beam software v8.26a:3-Hologic Inc., Bedford, MA).
10
DXA Scan Protocol for Small Animals
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The DXA scans were performed as previously described with modification [19] . In brief, the animals were anesthetized using chloral hydrate (10%, 3 ml/kg body weight, i.p.). DXA scans were performed with a fan beam QDR 4500 A densitometer (Hologic, Inc., Bedford, MA, USA) calibrated daily in accordance with the manufacturer's recommendations. The animals were positioned centrally at the bottom of a square. All DXA measurements and analyses were performed by the same investigator, and the data were analyzed using the small-animal mode of Hologic Discovery Software (Hologic, Inc., Bedford, USA).
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