Lumbar spondylolisthesis and prevalent vertebral fracture were both evaluated on plain lateral X-ray using imaging software (Synapse; Fujifilm, Tokyo, Japan). Spondylolisthesis was defined as an anterior/posterior slip greater than or equal to 3 mm. Vertebral fracture was defined as a decrease in vertebral height greater than 20% compared with caudal or cranial normal vertebrae by a semi-quantitative assessment [9] . Bone mineral density (BMD, g/cm 2 ) was measured by dual-energy X-ray absorptiometry using a QDR 4500 system (Hologic, Waltham, MA). Quality control (for the device) was performed by the daily assessment of a spine phantom. BMD was scanned in a whole-body mode, and BMD of the lumbar spine BMD was analyzed. Thoraco-lumbar scoliosis, defined as a Cobb angle greater than 10°, was evaluated on the whole-body image obtained through dual-energy X-ray absorptiometry, which was performed using the QDR 4500 system (Hologic ® , Waltham, MA).
Qdr4500 system
Manufactured by Hologic
Sourced in United States, United Kingdom
The QDR4500 system is a dual-energy X-ray absorptiometry (DXA) device designed for bone density measurement. It is used to assess bone mineral density and detect osteoporosis.
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Lab products found in correlation
14 protocols using qdr4500 system
1
Radiographic Evaluation of Spinal Disorders
2
Assessing Osteoporosis via DXA Scans
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DXA was employed to test BMD by using Hologic QDR 4500 system (Hologic Inc. Waltham, MA, USA). T scores were inferred based on their comparisons with peak bone mass of average 30 years old young individual of the same gender. On the basis of these T scores, those women were confirmed to have osteoporosis who had T score ≤ 2.5 and women without osteoporosis; who had T scores ≥ 1. The QDR system was standardized according to the guidelines of the manufacturer before testing. Inter- and intra-assay CVs for the checking of the BMD_FN and BMD_LS were 5.0 and 5.8, respectively.
3
Bone Mineral Density Assessment by DXA
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BMD of the women in supine position was measured with a Hologic QDR 4500 system (Hologic Inc., Waltham, MA, USA) using DXA. On the basis of T-scores obtained according to WHO guidelines [10 (link)], women were characterized as osteoporotic when the T-score was equal to or less than −2.5 standard deviation (SD), osteopenic when the T-score was observed between −1 to −2.5 SD and normal (without bone loss) when the T-score was −1 SD from the optimal peak bone density of healthy young adults of the same sex. The DXA system was calibrated every day before using it with the Phantoms supplied by the manufacturer. The coefficient of variation was observed to be less than 4 percent for the measurements of BMD at the hip and spine.
4
Comprehensive DXA-Based Bone and Body Composition Assessment
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At the screening visit, all participants underwent DXA scans on a Hologic QDR4500 system (Hologic, Bedford, MA, USA) by an International Society for Clinical Densitometry certified bone densitometry technologist. Body composition was assessed using whole-body scans, including measurements of percent body fat, fat mass, lean mass, and fat-free mass (laboratory precision of ≤1.1% CV for body composition). Areal BMD (g/cm2) was measured using DXA scans of the total body, lumbar spine, and hip region (laboratory precision of <0.8% CV at all three BMD sites). The results from DXA scans were expressed as a “T-score” to indicate the standard deviation (SD) of each participant from the young adult mean. The WHO classification5 (link) was used to define BMD categories, wherein participants were classified as osteopenic if T-scores were below –1.0 but greater than –2.5 at any site; or osteoporotic if T-scores were less than –2.5 at any site. The 10-year probability of major osteoporotic fracture or hip fracture was calculated using the trabecular bone score-adjusted fracture risk assessment tool (FRAX) (www.shef.ac.uk/FRAX
5
Dual-Energy X-Ray Absorptiometry for Bone Density
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BMD values for the lumbar spine (L) and the femoral neck (FN) were measured by dual-energy X-ray absorptiometry (DXA) using a QDR-4500 system (Hologic, Waltham, MA). The values were expressed relative to the standard deviation (SD) of age- and sex-matched normal Japanese BMD values provided by the manufacturer (Z-score). The coefficients of variation for the measurements of L-BMD and FN-BMD were less than 1%.
6
Diagnosing and Classifying Osteogenesis Imperfecta
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Diagnosis and classification were based on clinical and radiological characteristics according to the Sillence classification system [5 (link)]. In this study, every patient was evaluated at our clinic by one author, in person, to minimize inter-observer variation. For each patient, we recorded their height, weight, and bone mineral density (BMD) standard deviation scores (SDSs), walking ability and family history, and the occurrence of blue sclera, DI, hearing loss, bone deformity, and scoliosis. Height and weight were transformed to SDSs on the basis of a standard growth table for Taiwanese children and adolescents [9 (link)]. The BMD of the lumbar spine (L1–L4) was assessed using dual energy X-ray absorptiometry (DEXA) with a Hologic QDR 4500 system (Hologic, Bedford, MA, USA) [4 (link)]. The BMD results were converted to age- and gender-specific SDSs based on the normative reference data for BMD in Taiwanese children and adults [10 (link), 11 (link)]. Pamidronate therapy has been reported to increase BMD, decrease the fracture rate, and substantially improve functional status for OI patients [12 (link)]. However, none of our patients had received pamidronate treatment at the time of assessment.
7
Comprehensive Assessment of Bone Health
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DXA scans of the total body, lumbar spine, and dual hip were performed to assess areal BMD at screening, month 6, and month 12. Participants were scanned and analyzed on a Hologic QDR4500 system (Hologic, Bedford, MA) by an International Society for Clinical Densitometry certified bone densitometry technologist. Our lab has a precision of <0.8% CV at all three BMD sites (total body, spine and hip). In addition, femoral neck geometry and strength were estimated from dual hip scans by Hip Strength Analysis (HSA) [24 (link),25 (link)]. HSA is a feature of the Hologic APEX software that is used to estimate the structural properties of the hip and the measurements were obtained from the automatic analysis. Specific measurements obtained include femoral neck cross-sectional moment of inertia (CSMI), cross-sectional area (CSA), section modulus (Z), and diameter. Fracture risk assessment was determined using the trabecular bone score (TBS)-adjusted FRAX® tool (www.shef.ac.uk/FRAX ) [26 ,27 (link)], in which the algorithm computes 10-year probability of major osteoporotic fracture or hip fracture.
8
Lumbar Spine DXA Measurement Protocol
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The anteroposterior BMD values of the lumbar spine were measured by DXA using a QDR-4500 system, which was replaced by a Discovery system on 1 October 2008 (Hologic, Waltham, MA, USA). The coefficient of variation for measurements of spinal BMD was 1.0%.
9
Longitudinal Body Composition Assessment
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At baseline and week 52, body composition and total hip BMD were assessed using DXA. All participants underwent total body DXA scans on a Hologic QDR4500 system (Hologic, Bedford, MA, USA) performed by an International Society for Clinical Densitometry certified bone densitometry technologist. Laboratory precision for DXA measurement of total hip BMD was <0.8% coefficient of variation.
10
Body Composition Changes Over Time
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Every 6 months (baseline, months 6 and 12), a total body DXA scan was performed to assess body composition to include percent body fat, fat mass, lean mass and fat-free mass, as well as that of specific regions, such as the android, gynoid, trunk, legs, and arms. Participants were scanned on a Hologic QDR4500 system (Hologic, Bedford, MA). Our lab has a precision of ≤1.1% coefficient of variation (CV) for body composition.
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