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Sample records for absorptiometry dxa scan

  1. A review of the use of dual-energy X-ray absorptiometry (DXA) in rheumatology

    PubMed Central

    Tanner, S Bobo; Moore, Charles F

    2012-01-01

    The principal use of dual-energy X-ray absorptiometry (DXA) is to diagnose and monitor osteoporosis and therefore reduce fracture risk, associated morbidity, and mortality. In the field of rheumatology, DXA is an essential component of patient care because of both rheumatologists’ prescription of glucocorticoid treatment as well as the effects of rheumatological diseases on bone health. This review will summarize the use of DXA in the field of rheumatology, including the concern for glucocorticoid-induced osteoporosis, as well as the association of osteoporosis with a sampling of such rheumatologic conditions as rheumatoid arthritis (RA), systemic lupus erythematosus, ankylosing spondylitis, juvenile idiopathic arthritis, and scleroderma or systemic sclerosis. Medicare guidelines recognize the need to perform DXA studies in patients treated with glucocorticoids, and the World Health Organization FRAX tool uses data from DXA as well as the independent risk factors of RA and glucocorticoid use to predict fracture risk. However, patient access to DXA measurement in the US is in jeopardy as a result of reimbursement restrictions. DXA technology can simultaneously be used to discover vertebral fractures with vertebral fracture assessment and provide patients with a rapid, convenient, and low-radiation opportunity to clarify future fracture and comorbidity risks. An emerging use of DXA technology is the analysis of body composition of RA patients and thus the recognition of “rheumatoid cachexia,” in which patients are noted to have a worse prognosis even when the RA appears well controlled. Therefore, the use of DXA in rheumatology is an important tool for detecting osteoporosis, reducing fracture risk and unfavorable outcomes in rheumatological conditions. The widespread use of glucocorticoids and the underlying inflammatory conditions create a need for assessment with DXA. There are complications of conditions found in rheumatology that could be prevented with

  2. Segmental Musculoskeletal Examinations using Dual-Energy X-Ray Absorptiometry (DXA): Positioning and Analysis Considerations.

    PubMed

    Hart, Nicolas H; Nimphius, Sophia; Spiteri, Tania; Cochrane, Jodie L; Newton, Robert U

    2015-09-01

    Musculoskeletal examinations provide informative and valuable quantitative insight into muscle and bone health. DXA is one mainstream tool used to accurately and reliably determine body composition components and bone mass characteristics in-vivo. Presently, whole body scan models separate the body into axial and appendicular regions, however there is a need for localised appendicular segmentation models to further examine regions of interest within the upper and lower extremities. Similarly, inconsistencies pertaining to patient positioning exist in the literature which influence measurement precision and analysis outcomes highlighting a need for standardised procedure. This paper provides standardised and reproducible: 1) positioning and analysis procedures using DXA and 2) reliable segmental examinations through descriptive appendicular boundaries. Whole-body scans were performed on forty-six (n = 46) football athletes (age: 22.9 ± 4.3 yrs; height: 1.85 ± 0.07 cm; weight: 87.4 ± 10.3 kg; body fat: 11.4 ± 4.5 %) using DXA. All segments across all scans were analysed three times by the main investigator on three separate days, and by three independent investigators a week following the original analysis. To examine intra-rater and inter-rater, between day and researcher reliability, coefficients of variation (CV) and intraclass correlation coefficients (ICC) were determined. Positioning and segmental analysis procedures presented in this study produced very high, nearly perfect intra-tester (CV ≤ 2.0%; ICC ≥ 0.988) and inter-tester (CV ≤ 2.4%; ICC ≥ 0.980) reliability, demonstrating excellent reproducibility within and between practitioners. Standardised examinations of axial and appendicular segments are necessary. Future studies aiming to quantify and report segmental analyses of the upper- and lower-body musculoskeletal properties using whole-body DXA scans are encouraged to use the patient positioning and image analysis procedures outlined in this

  3. Segmental Musculoskeletal Examinations using Dual-Energy X-Ray Absorptiometry (DXA): Positioning and Analysis Considerations

    PubMed Central

    Hart, Nicolas H.; Nimphius, Sophia; Spiteri, Tania; Cochrane, Jodie L.; Newton, Robert U.

    2015-01-01

    Musculoskeletal examinations provide informative and valuable quantitative insight into muscle and bone health. DXA is one mainstream tool used to accurately and reliably determine body composition components and bone mass characteristics in-vivo. Presently, whole body scan models separate the body into axial and appendicular regions, however there is a need for localised appendicular segmentation models to further examine regions of interest within the upper and lower extremities. Similarly, inconsistencies pertaining to patient positioning exist in the literature which influence measurement precision and analysis outcomes highlighting a need for standardised procedure. This paper provides standardised and reproducible: 1) positioning and analysis procedures using DXA and 2) reliable segmental examinations through descriptive appendicular boundaries. Whole-body scans were performed on forty-six (n = 46) football athletes (age: 22.9 ± 4.3 yrs; height: 1.85 ± 0.07 cm; weight: 87.4 ± 10.3 kg; body fat: 11.4 ± 4.5 %) using DXA. All segments across all scans were analysed three times by the main investigator on three separate days, and by three independent investigators a week following the original analysis. To examine intra-rater and inter-rater, between day and researcher reliability, coefficients of variation (CV) and intraclass correlation coefficients (ICC) were determined. Positioning and segmental analysis procedures presented in this study produced very high, nearly perfect intra-tester (CV ≤ 2.0%; ICC ≥ 0.988) and inter-tester (CV ≤ 2.4%; ICC ≥ 0.980) reliability, demonstrating excellent reproducibility within and between practitioners. Standardised examinations of axial and appendicular segments are necessary. Future studies aiming to quantify and report segmental analyses of the upper- and lower-body musculoskeletal properties using whole-body DXA scans are encouraged to use the patient positioning and image analysis procedures outlined in this

  4. Cortical thickness estimation of the proximal femur from multi-view dual-energy X-ray absorptiometry (DXA)

    NASA Astrophysics Data System (ADS)

    Tsaousis, N.; Gee, A. H.; Treece, G. M.; Poole, K. E. S.

    2013-02-01

    Hip fracture is the leading cause of acute orthopaedic hospital admission amongst the elderly, with around a third of patients not surviving one year post-fracture. Although various preventative therapies are available, patient selection is difficult. The current state-of-the-art risk assessment tool (FRAX) ignores focal structural defects, such as cortical bone thinning, a critical component in characterizing hip fragility. Cortical thickness can be measured using CT, but this is expensive and involves a significant radiation dose. Instead, Dual-Energy X-ray Absorptiometry (DXA) is currently the preferred imaging modality for assessing hip fracture risk and is used routinely in clinical practice. Our ambition is to develop a tool to measure cortical thickness using multi-view DXA instead of CT. In this initial study, we work with digitally reconstructed radiographs (DRRs) derived from CT data as a surrogate for DXA scans: this enables us to compare directly the thickness estimates with the gold standard CT results. Our approach involves a model-based femoral shape reconstruction followed by a data-driven algorithm to extract numerous cortical thickness point estimates. In a series of experiments on the shaft and trochanteric regions of 48 proximal femurs, we validated our algorithm and established its performance limits using 20 views in the range 0°-171°: estimation errors were 0:19 +/- 0:53mm (mean +/- one standard deviation). In a more clinically viable protocol using four views in the range 0°-51°, where no other bony structures obstruct the projection of the femur, measurement errors were -0:07 +/- 0:79 mm.

  5. Comparison of DXA Scans and Conventional X-rays for Spine Morphometry and Bone Age Determination in Children.

    PubMed

    Hoyer-Kuhn, Heike; Knoop, Kai; Semler, Oliver; Kuhr, Kathrin; Hellmich, Martin; Schoenau, Eckhard; Koerber, Friederike

    2016-01-01

    Conventional lateral spine and hand radiographs are the standard tools to evaluate vertebral morphometry and bone age in children. Beside bone mineral density analyses, dual-energy X-ray absorptiometry (DXA) measurements with lower radiation exposure provide high-resolution scans which are not approved for diagnostic purposes. Data about the comparability of conventional radiographs and DXA in children are missing yet. The purpose of the trial was to evaluate whether conventional hand and spine radiographs can be replaced by DXA scans to diminish radiation exposure. Thirty-eight children with osteogenesis imperfecta or secondary osteoporosis or short stature (male, n=20; age, 5.0-17.0 yr) were included and assessed once by additional DXA (GE iDXA) of the spine or the left hand. Intraclass correlation coefficients (ICCs) were used to express agreement between X-ray and iDXA assessment. Evaluation of the spine morphometry showed reasonable agreement between iDXA and radiography (ICC for fish-shape, 0.75; for wedge-shape, 0.65; and for compression fractures, 0.70). Bone age determination showed excellent agreement between iDXA and radiography (ICC, 0.97). IDXA-scans of the spine in a pediatric population should be used not only to assess bone mineral density but also to evaluate anatomic structures and vertebral morphometry. Therefore, iDXA can replace some radiographs in children with skeletal diseases.

  6. The validity of commonly used adipose tissue body composition equations relative to dual energy X-ray absorptiometry (DXA) in gaelic games players.

    PubMed

    Doran, D A; Mc Geever, S; Collins, K D; Quinn, C; McElhone, R; Scott, M

    2014-02-01

    Dual-energy X-ray absorptiometry (DXA) and adipose tissue percentage estimates (AT%) derived from regression based skinfold equations were compared. 35 Gaelic games players [20.9 ± 1.7 years; 78.1 ± 8.6 kg; 179.5 ± 5.7 cm] underwent whole body fan beam DXA scans following a standardised protocol and assessment of skinfold thickness at 8 sites. Adipose tissue% from the sum of skinfolds and/or via body density were calculated for general and athlete specific equations (SKf-AT %). The relationship, i. e., proportional bias, fixed bias and random error (SEE) between DXA-AT % and AT % derived from the 6 skinfold equations were determined using least squares regression analysis. Skinfold AT% estimates were underestimated relative to DXA-AT % across all skinfold equations except that of Durnin and Wormersley [9] (D&W-∑(4AT %)) (16.7 ± 3.4 vs. 16.6 ± 4.0 %). All equations demonstrated 95 % prediction intervals ranges exceeding ~10 %. Each equation failed to predict AT% relative to DXA within an accepted ± 3.5 % anthropometric error rate. It is recommended that the conversion of absolute skinfold thickness to an AT % is avoided and that the skinfold equations assessed herein are not utilised in Gaelic games players. Alternate 'sum of skinfold' approaches should be considered.

  7. Accuracy of dual energy X-ray absorptiometry (DXA) in assessing carcass composition from different pig populations.

    PubMed

    Soladoye, O P; López Campos, Ó; Aalhus, J L; Gariépy, C; Shand, P; Juárez, M

    2016-11-01

    The accuracy of dual energy X-ray absorptiometry (DXA) in assessing carcass composition from pigs with diverse characteristics was examined in the present study. A total of 648 pigs from three different sire breeds, two sexes, two slaughter weights and three different diets were employed. DXA estimations were used to predict the dissected/chemical yield for lean and fat of carcass sides and primal cuts. The accuracy of the predictions was assessed based on coefficient of determination (R(2)) and residual standard deviation (RSD). The linear relationships for dissected fat and lean for all the primal cuts and carcass sides were high (R(2)>0.94, P<0.01), with low RSD (<1.9%). Relationships between DXA and chemical fat and lean of pork bellies were also high (R(2)>0.94, P<0.01), with RSD <2.9%. These linear relationships remained high over the full range of variation in the pig population, except for sire breed, where the coefficient of determination decreased when carcasses were classified based on this variable. PMID:27395824

  8. Radiographic morphometry and densitometry predict strength of cadaveric proximal humeri more reliably than age and DXA scan density.

    PubMed

    Skedros, John G; Knight, Alex N; Pitts, Todd C; O'Rourke, Peter J; Burkhead, Wayne Z

    2016-02-01

    Methods are needed for identifying poorer quality cadaver proximal humeri to ensure that they are not disproportionately segregated into experimental groups for fracture studies. We hypothesized that measurements made from radiographs of cadaveric proximal humeri are stronger predictors of fracture strength than chronological age or bone density values derived from dual-energy x-ray absorptiometry (DXA) scans. Thirty-three proximal humeri (range: 39-78 years) were analyzed for: (1) bone mineral density (BMD, g/cm(2)) using DXA, (2) bulk density (g/cm(3)) using DXA and volume displacement, (3) regional bone density in millimeters of aluminum (mmAl) using radiographs, and (4) regional mean (medial+lateral) cortical thickness and cortical index (CI) using radiographs. The bones were then fractured simulating a fall. Strongest correlations with ultimate fracture load (UFL) were: mean cortical thickness at two diaphyseal locations (r = 0.71; p < 0.001), and mean mmAl in the humeral head (r = 0.70; p < 0.001). Weaker correlations were found between UFL and DXA-BMD (r = 0.60), bulk density (r = 0.43), CI (r = 0.61), and age (r = -0.65) (p values <0.01). Analyses between UFL and the product of any two characteristics showed six combinations with r-values >0.80, but none included DXA-derived density, CI, or age. Radiographic morphometric and densitometric measurements from radiographs are therefore stronger predictors of UFL than age, CI, or DXA-derived density measurements. PMID:26218571

  9. DXA: Technical aspects and application.

    PubMed

    Bazzocchi, Alberto; Ponti, Federico; Albisinni, Ugo; Battista, Giuseppe; Guglielmi, Giuseppe

    2016-08-01

    The key role of dual-energy X-ray absorptiometry (DXA) in the management of metabolic bone diseases is well known. The role of DXA in the study of body composition and in the clinical evaluation of disorders which directly or indirectly involve the whole metabolism as they may induce changes in body mass and fat percentage is less known or less understood. DXA has a range of clinical applications in this field, from assessing associations between adipose or lean mass and the risk of disease to understanding and measuring the effects of pathophysiological processes or therapeutic interventions, in both adult and paediatric human populations as well as in pre-clinical settings. DXA analyses body composition at the molecular level that is basically translated into a clinical model made up of fat mass, non-bone lean mass, and bone mineral content. DXA allows total and regional assessment of the three above-mentioned compartments, usually by a whole-body scan. Since body composition is a hot topic today, manufacturers have steered the development of DXA technology and methodology towards this. New DXA machines have been designed to accommodate heavier and larger patients and to scan wider areas. New strategies, such as half-body assessment, permit accurate body scan and analysis of individuals exceeding scan field limits. Although DXA is a projective imaging technique, new solutions have recently allowed the differential estimate of subcutaneous and intra-abdominal visceral fat. The transition to narrow fan-beam densitometers has led to faster scan times and better resolution; however, inter- or intra-device variation exists depending on several factors. The purposes of this review are: (1) to appreciate the role of DXA in the study of body composition; (2) to understand potential limitations and pitfalls of DXA in the analysis of body composition; (3) to learn about technical elements and methods, and to become familiar with biomarkers in DXA. PMID:27157852

  10. Evolution of bisphosphonate-related atypical fracture retrospectively observed with DXA scanning.

    PubMed

    Ahlman, Mark A; Rissing, Michael S; Gordon, Leonie

    2012-02-01

    We present a case of a 61-year-old female with history of long-term bisphosphonate therapy for osteoporosis initially diagnosed by screening dual-energy X-ray absorptiometry (DXA). After 4 years of treatment with bisphosphonates, the patient presented to primary care with left hip pain. Diagnostic hip radiographs were interpreted as normal, and she continued to take bisphosphonates. Two months later, she experienced a complete transverse subtrochanteric left femur fracture after minimal trauma. The patient underwent open reduction and internal fixation. Review of the patient's postoperative films revealed lateral subtrochanteric cortical beaking at the fracture. This type of "atypical" fracture has been reported to be a result of chronic bisphosphonate-associated fractures with high specificity. In addition, the right femur also showed cortical beaking with a horizontal linear lucency in an identical location, suggesting an impending fracture. Longitudinal review of the both diagnostic radiographs as well as DXA images shows a stepwise development of these subtrochanteric abnormalities in both femurs. A current hypothesis regarding the pathophysiology of bisphosphonate-associated fracture is that the medication inhibits bone turnover and repair of microscopic trauma. A cycle of defective repair and continual microtrauma compounded over time gradually weakens the bone and creates an architectural conduit for transverse or "atypical" fracture. Standard practice is not to use DXA as a diagnostic "image." We present this case to show that a common location and classic appearance of subtrochanteric bisphosphonate-associated fractures may be clearly visualized on absorptiometry images long before fracture. This observation is important because the majority of patients taking bisphosphonate therapy also receive regular DXA imaging. Because of the chronicity of standard bone-density monitoring for these patients throughout their treatment regimen, DXA may find a role for

  11. Skeletal Recovery Following Long-Duration Spaceflight Missions as Determined by Preflight and Postflight DXA Scans of 45 Crew Members

    NASA Technical Reports Server (NTRS)

    Sibonga, J. D.; Evans, H. J.; Sung, H. G.; Spector, E. R.; Lang, T. F.; Oganov, V. S.; Bakulin, A. V.; Shackelford, L. C.; LeBlanc, A. D.

    2006-01-01

    Introduction: The loss of bone mineral in astronauts during spaceflight has been investigated throughout the more than 40 years of bone research in space. Consequently, it is a medical requirement at NASA that changes in bone mass be monitored in crew members by measurements of bone mineral density (BMD) with dual-energy x-ray absorptiometry (DXA). This report is the first to evaluate medical data to address the recovery of bone mineral that is lost during spaceflight. Methods: DXA scans are performed before and after flight in astronauts who serve on long-duration missions (4-6 months) to ensure that medical standards for flight certification are met, to evaluate the effects of spaceflight and to monitor the restoration to preflight BMD status after return to Earth. Through cooperative agreements with the Russian Space Agency, the Bone and Mineral Lab at NASA Johnson Space Center (Houston, TX), also had access to BMD data from cosmonauts who had flown on long-duration missions yielding data from a total of 45 individual crew members. Changes in BMD (between 56 different sets of pre- and postflight measurements) were plotted as a function of time (days after landing); plotted data were fitted to an exponential mathematical model that determined i) BMD change at day 0 after landing and ii) the number of days after which 50% of the lost bone was recovered ("Recovery Half-Life"). These fits were performed for BMD of the lumbar spine, trochanter, pelvis, femoral neck and calcaneus. Results: In sum, averaged losses of bone mineral after spaceflight ranged between 2-9% for sites in the axial and appendicular skeleton. The fitted postflight BMD values predicted a 50% recovery of bone loss for all sites within 9 months.

  12. Accuracy of DXA scanning of the thoracic spine: cadaveric studies comparing BMC, areal BMD and geometric estimates of volumetric BMD against ash weight and CT measures of bone volume.

    PubMed

    Sran, Meena M; Khan, Karim M; Keiver, Kathy; Chew, Jason B; McKay, Heather A; Oxland, Thomas R

    2005-12-01

    Biomechanical studies of the thoracic spine often scan cadaveric segments by dual energy X-ray absorptiometry (DXA) to obtain measures of bone mass. Only one study has reported the accuracy of lateral scans of thoracic vertebral bodies. The accuracy of DXA scans of thoracic spine segments and of anterior-posterior (AP) thoracic scans has not been investigated. We have examined the accuracy of AP and lateral thoracic DXA scans by comparison with ash weight, the gold-standard for measuring bone mineral content (BMC). We have also compared three methods of estimating volumetric bone mineral density (vBMD) with a novel standard-ash weight (g)/bone volume (cm3) as measured by computed tomography (CT). Twelve T5-T8 spine segments were scanned with DXA (AP and lateral) and CT. The T6 vertebrae were excised, the posterior elements removed and then the vertebral bodies were ashed in a muffle furnace. We proposed a new method of estimating vBMD and compared it with two previously published methods. BMC values from lateral DXA scans displayed the strongest correlation with ash weight (r=0.99) and were on average 12.8% higher (p<0.001). As expected, BMC (AP or lateral) was more strongly correlated with ash weight than areal bone mineral density (aBMD; AP: r=0.54, or lateral: r=0.71) or estimated vBMD. Estimates of vBMD with either of the three methods were strongly and similarly correlated with volumetric BMD calculated by dividing ash weight by CT-derived volume. These data suggest that readily available DXA scanning is an appropriate surrogate measure for thoracic spine bone mineral and that the lateral scan might be the scan method of choice. PMID:15616862

  13. A study on the effects of a calcium drug on the bone mineral density (BMD) by using dual-energy X-ray Absorptiometry (DXA)

    NASA Astrophysics Data System (ADS)

    Kim, Eun-Hye; Kim, Ho-Sung; Dong, Kyung-Rae; Park, Yong-Soon; Chung, Woon-Kwan; Cho, Jae-Hwan

    2012-12-01

    Measurements of osteoporosis might contain errors caused by the calcium drug used in the prevention and the treatment of osteoporosis. This study conducted a lumbar spine phantom experiment to examine whether a calcium drug can influence the measured values of the bone mineral density (BMD) because of the drug taken by a real patient remaining undigested in the stomach. Dual-energy X-ray Absorptiometry (DXA) was used to measure the BMD for a calcium-drug in an equipment-dedicated lumbar spine phantom and 10 patients selected for the BMD measurement. Three types of drugs that are prescribed in actual clinical practice calcium drugs were used for the phantom experiment, and the drugs were divided into a fixed dose, 1/2 of the fixed dose, 1/4 of the fixed dose and 1/8 of the fixed dose. Without the drugs included, the phantom was scanned 60 times continuously to calculate the baseline BMD. The BMD was measured as the calcium drug coated with paraffin was placed in the lumbar vertebra 2 and the soft tissue region of the phantom. To determine when the drug was invisible to the naked eye are measured, the BMD at different drug dilutions. The measurements were conducted three times to calculate the mean. In the patient experiment, patients were selected who visited hospital after taking the drug before measuring the BMD. After a certain time had passed, the BMD was measured again to examine the difference in images and the change in BMD values due to the calcium-drug intake. The BMD measurements of lumbar 1-4 in the phantom were higher, with statistical significant, than the least significant change (LSC) in the bone region for all three drugs (Ca carbonate, Ca citrate and Ca cholecalciferol), showing a significant increase. On the other hand, there was no significant change in the soft tissue. When Ca Cholecalciferol was used in a fixed dose, the BMD of L2 increased by 11.6%, showing the largest increase among the drugs examined, but only a 2.8% increase in the BMD of L1

  14. Prenatal pesticide exposure and PON1 genotype associated with adolescent body fat distribution evaluated by dual X-ray absorptiometry (DXA).

    PubMed

    Tinggaard, J; Wohlfahrt-Veje, C; Husby, S; Christiansen, L; Skakkebaek, N E; Jensen, T K; Grandjean, P; Main, K M; Andersen, H R

    2016-07-01

    Many modern pesticides have endocrine disrupting abilities and early-life exposure may affect growth and disease risk later in life. Previously, we reported associations between prenatal pesticide exposure and higher childhood body fat content measured by anthropometry. The associations were affected by child PON1 Q192R genotype. We aimed to study whether prenatal pesticide exposure was still associated with body fat content and distribution in the children at puberty and the potential impact of both maternal and child PON1 Q192R genotype. In this prospective cohort study of 247 children born by occupationally exposed or unexposed women (greenhouse workers and controls) two follow-up examinations (age 10-15 and 11-16 years) including simple anthropometry, skinfold measurements, pubertal staging and blood sampling were performed. Total and regional fat% was determined by dual X-ray absorptiometry (DXA) at age 10-15. Prenatal pesticide exposure was associated with increased total, android, and gynoid fat percentage (DXA) at age 10-15 years after adjustment for sex, socioeconomic status, and puberty (all β = 0.5 standard deviation score (SDS) p < 0.05). Stratified by sex, the associations were significant in girls (total fat: β = 0.7 SDS, android-gynoid ratio: β = 0.1, both p < 0.05), but not in boys. Carrying the R-allele (child or mother, separately, or both) augmented the differences between exposed and unexposed children (total fat: β = 1.0 SDS, β = 0.8 SDS, p < 0.05, respectively, and β = 1.2 SDS, p < 0.01). No exposure-related differences were found if either the child or mother had the QQ wild-type. At age 11-16, exposed children tended to have a higher total fat% estimated by skinfolds than unexposed children (p = 0.06). No significant associations between prenatal exposure and body mass index or waist circumference were found. Prenatal pesticide exposure was associated with higher adolescent body fat content, including android

  15. Random field assessment of inhomogeneous bone mineral density from DXA scans can enhance the differentiation between postmenopausal women with and without hip fractures

    PubMed Central

    Dong, Xuanliang Neil; Pinninti, Rajeshwar; Lowe, Timothy; Cussen, Patricia; Ballard, Joyce E.; Paolo, David Di; Shirvaikar, Mukul

    2015-01-01

    Bone mineral density (BMD) measurements from Dual-energy X-ray Absorptiometry (DXA) alone cannot account for all factors associated with the risk of hip fractures. For example, the inhomogeneity of bone mineral density in the hip region also contributes to bone strength. In the stochastic assessment of bone inhomogeneity, the BMD map in the hip region is considered as a random field and stochastic predictors can be calculated by fitting a theoretical model onto the experimental variogram of the BMD map. The objective of this study was to compare the ability of bone mineral density and stochastic assessment of inhomogeneous distribution of bone mineral density in predicting hip fractures for postmenopausal women. DXA scans in the hip region were obtained from postmenopausal women with hip fractures (N=47, Age: 71.3±11.4 years) and without hip fractures (N=45, Age: 66.7±11.4 years). Comparison of BMD measurements and stochastic predictors in assessing bone fragility was based on the area under the receiver operating characteristic curves (AUC) from logistic regression analyses. Although stochastic predictors offered higher accuracy (AUC=0.675) in predicting the risk of hip fractures than BMD measurements (AUC=0.625), such difference was not statistically significant (p=0.548). Nevertheless, the combination of stochastic predictors and BMD measurements had significantly (p=0.039) higher prediction accuracy (AUC=0.748) than BMD measurements alone. This study demonstrates that stochastic assessment of bone mineral distribution from DXA scans can serve as a valuable tool in enhancing the prediction of hip fractures for postmenopausal women in addition to BMD measurements. PMID:25683520

  16. Prediction of incident hip fracture with the estimated femoral strength by finite element analysis of DXA Scans in the study of osteoporotic fractures.

    PubMed

    Yang, Lang; Palermo, Lisa; Black, Dennis M; Eastell, Richard

    2014-12-01

    A bone fractures only when loaded beyond its strength. The purpose of this study was to determine the association of femoral strength, as estimated by finite element (FE) analysis of dual-energy X-ray absorptiometry (DXA) scans, with incident hip fracture in comparison to hip bone mineral density (BMD), Fracture Risk Assessment Tool (FRAX), and hip structure analysis (HSA) variables. This prospective case-cohort study included a random sample of 1941 women and 668 incident hip fracture cases (295 in the random sample) during a mean ± SD follow-up of 12.8 ± 5.7 years from the Study of Osteoporotic Fractures (n = 7860 community-dwelling women ≥67 years of age). We analyzed the baseline DXA scans (Hologic 1000) of the hip using a validated plane-stress, linear-elastic finite element (FE) model of the proximal femur and estimated the femoral strength during a simulated sideways fall. Cox regression accounting for the case-cohort design assessed the association of estimated femoral strength with hip fracture. The age-body mass index (BMI)-adjusted hazard ratio (HR) per SD decrease for estimated strength (2.21; 95% CI, 1.95-2.50) was greater than that for total hip (TH) BMD (1.86; 95% CI, 1.67-2.08; p < 0.05), FN BMD (2.04; 95% CI, 1.79-2.32; p > 0.05), FRAX scores (range, 1.32-1.68; p < 0.0005), and many HSA variables (range, 1.13-2.43; p < 0.005), and the association was still significant (p < 0.05) after further adjustment for hip BMD or FRAX scores. The association of estimated strength with incident hip fracture was strong (Harrell's C index 0.770), significantly better than TH BMD (0.759; p < 0.05) and FRAX scores (0.711-0.743; p < 0.0001), but not FN BMD (0.762; p > 0.05). Similar findings were obtained for intracapsular and extracapsular fractures. In conclusion, the estimated femoral strength from FE analysis of DXA scans is an independent predictor and performs at least as well as FN BMD in predicting incident

  17. Association between Abdominal Fat (DXA) and Its Subcomponents (CT Scan) before and after Weight Loss in Obese Postmenopausal Women: A MONET Study.

    PubMed

    Doyon, Caroline Y; Brochu, Martin; Messier, Virginie; Lavoie, Marie-Ève; Faraj, May; Doucet, Eric; Rabasa-Lhoret, Rémi; Dionne, Isabelle J

    2011-01-01

    Introduction. Subcutaneous fat (ScF) and visceral fat (VF) measurements using CT scan are expensive and may imply significant radiation doses. Cross-sectional studies using CT scan showed that ScF and VF are significantly correlated with abdominal fat measured by DXA (AF-DXA). The association has not been studied after a weight loss. Objective. To determine (1) the associations between AF-DXA and ScF and VF before and after weight loss and (2) the associations between their changes. Methods. 137 overweight/obese postmenopausal women were divided in two groups (1-caloric restriction or 2-caloric restriction + resistance training). AF was assessed using DXA and CT scan. Results. Correlations between AF-DXA and ScF (before: r = 0.87, after; r = 0.87; P < .01) and, AF-DXA and VF (before: r = 0.61, after; r = 0.69; P < .01) are not different before and after the weight loss. Correlations between delta AF-DXA and delta ScF (r = 0.72; P < .01) or delta VF (r = 0.51; P < .01) were found. Conclusion. The use of AF-DXA as a surrogate for VF after weight loss is questionable, but may be interesting for ScF.

  18. Clinical comparison of a novel breast DXA technique to mammographic density

    SciTech Connect

    Shepherd, John A.; Herve, Lionel; Landau, Jessie; Fan Bo; Kerlikowske, Karla; Cummings, Steve R.

    2006-05-15

    We compare mammography breast density (BD{sub MD}) to the measure of breast composition using a clinical dual energy absorptiometry (DXA) system (BD{sub DXA}) calibrated to measure breast density. A DXA scanning protocol was developed to scan breasts isolated in the DXA scan field in either a prone pendulous or decubitus mediolateral position. A total of 17 participants were recruited among women undergoing clinical mammography examinations. Each participant had duplicate DXA scans and duplicate craniocaudal-view mammograms of their right breast with repositioning between each scan and one DXA and one craniocaudal-view mammogram of their left breast. The in vivo repeatability (RMS SD) of BD{sub DXA} and BD{sub MD} on duplicate scans was found to be 1.2% for BD{sub DXA} and 1.4% for BD{sub MD} when repeat BD{sub MD} measures were made on the same day. When repeat BD{sub MD} measures of the same breast were made more than 50 days apart, the repeatability decreased to 5.5%. Left and right breast measurements were highly correlated with both techniques at r{sup 2}=0.98 for BD{sub DXA} and r{sup 2}=0.86 for BD{sub MD}. Moderate correlation (r{sup 2}=0.52) was found between BD{sub DXA} and BD{sub MD} measurements. However, after recalibrating the DXA system to mammography reference materials, negative percent fibroglandular values were measured for the most fatty breasts. Thus, our results are reproducible and accurate to common mammography tissue standards, but did not accurately reflect true percent fibroglandular levels and further development of phantom standards are necessary. We conclude that breast composition can be precisely evaluated and assessed with clinical DXA densitometers at a lower dose than with mammographic breast density methods.

  19. Solid anthropomorphic infant whole body DXA phantom: Design, evaluation, and multisite testing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dual energy X-ray absorptiometry (DXA) requires phantoms for quality control and cross-calibration. No commercially available phantoms are designed specifically for infant whole-body scanning. We fabricated a phantom closely matching a 7-kg human infant in body habitus using PVC, nylon-mix, and poly...

  20. Method and apparatus for multiple-projection, dual-energy x-ray absorptiometry scanning

    NASA Technical Reports Server (NTRS)

    Charles, Jr., Harry K. (Inventor); Beck, Thomas J. (Inventor); Feldmesser, Howard S. (Inventor); Magee, Thomas C. (Inventor)

    2007-01-01

    Methods and apparatuses for advanced, multiple-projection, dual-energy X-ray absorptiometry scanning systems include combinations of a conical collimator; a high-resolution two-dimensional detector; a portable, power-capped, variable-exposure-time power supply; an exposure-time control element; calibration monitoring; a three-dimensional anti-scatter-grid; and a gantry-gantry base assembly that permits up to seven projection angles for overlapping beams. Such systems are capable of high precision bone structure measurements that can support three dimensional bone modeling and derivations of bone strength, risk of injury, and efficacy of countermeasures among other properties.

  1. A novel approach to fracture-risk-assessment in osteoporosis by ROI-oriented application of the Minkowski-functionals to dual x-ray absorptiometry scans of the hip

    NASA Astrophysics Data System (ADS)

    Boehm, Holger F.; Panteleon, Alexandra; Vogel, Tobias; Burklein, Dominik; Reiser, Maximilian

    2008-03-01

    Fractures of the proximal femur represent the worst complication in osteoporosis with a mortality rate of up to 50% during the first post-traumatic year. Bone mineral density (BMD) as obtained from dual energy x-ray absorptiometry (DXA) is a good predictor of fracture risk. However, there is a considerable overlap in the BMD-results between individuals who have fractured and those who have not. As DXA uses highly standardized radiographic projection images to obtain the densitometric information, it can be postulated that these images contain much more information than just mineral density. Lately, geometric dimensions, e.g. hip axis length (HAL) or femoral neck axis length (FNAL), are considered in conjunction with BMD, which may allow to enhance the predictive potential of bone mass measurements. In recent studies we sucessfully introduced a novel methodology for topological analysis of multi-dimensional graylevel datasets, that, for instance, allows to predict the ultimate mechanical strength of femoral bone specimens. The new topolocial parameters are based on the so called Minkowski Functionals (MF), which represent a set of topographical descriptors that can be used universally. Since the DXA-images are multi-graylevel datasets in 2D obtained in a standardized way, they are ideally suited to be processed by the new method. In this study we introduce a novel algorithm to evaluate DXA-scans of the proximal femur using quantitative image analysis procedures based on the MF in 2D. The analysis is conducted in four defined regions of interest in analogy to the standard densitometric evaluation. The objective is to provide a tool to identifiy individuals with critically reduced mechanical competence of the hip. The result of the new method is compared with the evaluation bone mineral density obtained by DXA, which - at present - is the clinical standard of reference.

  2. Distal radius strength: a comparison of DXA-derived vs pQCT-measured parameters in adolescent females.

    PubMed

    Dowthwaite, Jodi N; Hickman, Rebecca M; Kanaley, Jill A; Ploutz-Snyder, Robert J; Spadaro, Joseph A; Scerpella, Tamara A

    2009-01-01

    Although quantitative computed tomography (QCT) is considered the gold standard for in vivo densitometry, dual-energy X-ray absorptiometry (DXA) scans assess larger bone regions and are more appropriate for pediatric longitudinal studies. Unfortunately, DXA does not yield specific bone architectural output. To address this issue in healthy, postmenarcheal girls, Sievänen's distal radius formulae [1996] were applied to derive indices of bone geometry, volumetric bone mineral density (vBMD), and strength from DXA data; results were compared to peripheral quantitative computed tomography (pQCT) output. Contemporaneous scans were performed on the left, distal radii of 35 gymnasts, ex-gymnasts, and nongymnasts (aged 13.3-20.4 yr, mean 16.6 yr). For 4% and 33% regions, pQCT measured cross-sectional areas (CSAs) and vBMD; comparable DXA indices were generated at ultradistal and 1/3 regions. Index of structural strength in axial compression was calculated from 4% pQCT and DXA output for comparison; 33% pQCT strength-strain index was compared to 1/3 DXA section modulus. Sievänen DXA indices were significantly, positively correlated with pQCT output (R=+0.61 to +0.98; p<0.0001). At the distal radius, in healthy postmenarcheal girls, Sievänen's method yielded potentially useful DXA indices of diaphyseal cortical CSA and bone strength at both the diaphysis (section modulus) and the metaphysis (index of structural strength in axial compression).

  3. Unexplained high BMD in DXA-scanned patients is generalized throughout the skeleton and characterized by thicker cortical and trabecular bone.

    PubMed

    Lomholt, S; Amstrup, A K; Moser, E; Jakobsen, N F B; Mosekilde, L; Vestergaard, P; Rejnmark, L

    2015-04-01

    Unexplained high bone mineral density (BMD) is a rare condition and the mechanisms responsible are yet to be described in detail. The aim of the study was to identify patients with unexplained high BMD from a local DXA database and compare their radiological phenotype with an age- and a gender-matched group of population-based controls. We defined high BMD as a DXA Z-score ≥ + 2.5 at the total hip and lumbar spine. We characterized the findings as "unexplained" if no osteodegenerative changes, bone metabolic disease, or arthritis at the hip or lumbar spine was observed. All participants were investigated with high-resolution peripheral quantitative computed tomography (HR-pQCT), QCT, DXA, fasting blood samples, a 24-h urine sample, and questionnaires. The DXA database contained data on 25,118 patients. Initially, 138 (0.55%) potential participants with high BMD were identified, and during the study ten additional cases were identified from new DXA scans. Sixty-seven patients accepted to participate in the study, and among these we identified 15 women and one man with unexplained high BMD. These 15 women had higher BMD throughout the skeleton relative to controls, similar area/volume at the hip and the distal extremities, a higher number of trabeculae, which was thicker than in the controls, and a higher finite element estimated bone strength. The 15 women were heavier and had a higher fat mass then controls. We conclude that patients with unexplained high BMD have a generalized high BMD phenotype throughout their skeleton, which is characterized with a denser microarchitecture.

  4. Body composition in taller individuals using DXA: A validation study for athletic and non-athletic populations.

    PubMed

    Santos, Diana A; Gobbo, Luís A; Matias, Catarina N; Petroski, Edio L; Gonçalves, Ezequiel M; Cyrino, Edilson S; Minderico, Claudia S; Sardinha, Luís B; Silva, Analiza M

    2013-01-01

    Dual energy X-ray absorptiometry (DXA) cannot be used to evaluate participants taller than the scan area. We aimed to analyse the accuracy of bone mineral content, fat mass, and lean mass assessed with DXA whole-body scan and from the sum of two scans (head and trunk plus limbs). Participants were 31 athletes (13 males and 18 females) and 65 non-athletes (34 males and 31 females), that fit within the DXA scan area. Three scans were performed using a Hologic Explorer-W fan-beam densitometer: a whole-body scan used as the reference; a head scan; and a trunk and limbs scan. The sum of the head scan and the trunk and limbs scan was used as the alternative procedure. Multiple regression and agreement analysis were performed. Non-significant differences between methods were observed for fat mass (0.06 kg) and lean mass (-0.07 kg) while bone mineral content from the alternative procedure differed from the reference scan (0.009 kg). The alternative procedure explained > 99% of the variance in the reference scan and low limits of agreement were observed. Precision analysis indicated low pure errors and the higher coefficients of variation were found for fat mass (whole-body: 3.70%; subtotal: 4.05%). The method proposed is a valid and simple solution to be used in individuals taller than the DXA scan area, including athletes engaged in sports recognised for including very tall competitors. PMID:23092580

  5. Bone age assessment by dual-energy X-ray absorptiometry in children: an alternative for X-ray?

    PubMed Central

    Heppe, D H M; Taal, H R; Ernst, G D S; Van Den Akker, E L T; Lequin, M M H; Hokken-Koelega, A C S; Geelhoed, J J M; Jaddoe, V W V

    2012-01-01

    Objective The aim of the study was to validate dual-energy X-ray absorptiometry (DXA) as a method to assess bone age in children. Methods Paired dual-energy X-ray absorptiometry (DXA) scans and X-rays of the left hand were performed in 95 children who attended the paediatric endocrinology outpatient clinic of University Hospital Rotterdam, the Netherlands. We compared bone age assessments by DXA scan with those performed by X-ray. Bone age assessment was performed by two blinded observers according to the reference method of Greulich and Pyle. Intra-observer and interobserver reproducibility were investigated using the intraclass correlation coefficient (ICC), and agreement was tested using Bland and Altman plots. Results The intra-observer ICCs for both observers were 0.997 and 0.991 for X-ray and 0.993 and 0.987 for DXA assessments. The interobserver ICC was 0.993 and 0.991 for X-ray and DXA assessments, respectively. The mean difference between bone age assessed by X-ray and DXA was 0.11 years. The limits of agreement ranged from −0.82 to 1.05 years, which means that 95% of all differences between the methods were covered by this range. Conclusions Results of bone age assessment by DXA scan are similar to those obtained by X-ray. The DXA method seems to be an alternative for assessing bone age in a paediatric hospital-based population. PMID:21586503

  6. SINISTER CAUSE OF HIGH BONE MINERAL DENSITY ON DUAL ENERGY X-RAY ABSORPTIOMETRY.

    PubMed

    Razi, Mairah; Hassan, Aamna

    2016-01-01

    Dual energy X-ray absorptiometry (DXA) has an established, well standardized role in the measurement of bone mineral density (BMD). In routine clinical practice, the main focus of bone densitometry is to identify low bone mass for the diagnosis and monitoring of osteoporosis particularly in postmenopausal females and in high risk individuals. Less commonly, elevated BMD can also be seen on routine DXA scanning usually due to degenerative disease. However, a range of other skeletal disorders can also lead to high BMD. Careful recognition of various artefacts and pathologic processes that can falsely elevate the BMD is essential for accurate DXA scan analysis and reporting. We present a case of high BMD in a patient of prostate carcinoma with widespread sclerotic metastases. PMID:27323594

  7. Technical note: Prediction of chemical rib section composition by dual energy X-ray absorptiometry in Zebu beef cattle.

    PubMed

    Prados, L F; Zanetti, D; Amaral, P M; Mariz, L D S; Sathler, D F T; Filho, S C Valadares; Silva, F F; Silva, B C; Pacheco, M C; Alhadas, H M; Chizzotti, M L

    2016-06-01

    It is expensive and laborious to evaluate carcass composition in beef cattle. The objective of this study was to evaluate a method to predict the 9th to 11th rib section (rib) composition through empirical equations using dual energy X-ray absorptiometry (DXA). Dual energy X-ray absorptiometry is a validated method used to describe tissue composition in humans and other animals, but few studies have evaluated this technique in beef cattle, and especially in the Zebu genotype. A total of 116 rib were used to evaluate published prediction equations for rib composition and to develop new regression models using a cross-validation procedure. For the proposed models, 93 ribs were randomly selected to calculate the new regression equations, and 23 different ribs were randomly selected to validate the regressions. The rib from left carcasses were taken from Nellore and Nellore × Angus bulls from 3 different studies and scanned using DXA equipment (GE Healthcare, Madison, WI) in the Health Division at Universidade Federal de Viçosa (Viçosa, Brazil). The outputs of the DXA report were DXA lean (g), DXA fat free mass (g), DXA fat mass (g), and DXA bone mineral content (BMC; g). After being scanned, the rib were dissected, ground, and chemically analyzed for total ether extract (EE), CP, water, and ash content. The predictions of rib fat and protein from previous published equations were different ( < 0.01) from the observed composition. New equations were established through leave-one-out cross-validation using the REG procedure in SAS. The equations were as follows: lean (g) = 37.082 + 0.907× DXA lean ( = 0.95); fat free mass (g) = 103.224 + 0.869 × DXA fat free mass ( = 0.93); EE mass (g) = 122.404 + 1.119 × DXA fat mass ( = 0.86); and ash mass (g) = 18.722 + 1.016 × DXA BMC ( = 0.39). The equations were validated using Mayer's test, the concordance correlation coefficient, and the mean square error of prediction for decomposition. For both equations, Mayer's test

  8. Increasing body fat mass reverses bone loss in osteopenia as detected by dual-energy X-ray absorptiometry scans

    PubMed Central

    Hedges, William P.; Bukhari, Marwan

    2016-01-01

    Objective Low body mass index (BMI) is a known risk factor for osteoporosis and is part of the FRAX™ 10-year fracture risk stratification tool for predicting fragility fractures. Little is known regarding the effects of changing body composition on bone mineral density (BMD). However, increasing fat mass (FM) improves BMD in young women with anorexia nervosa. This study aimed to assess whether changes in FM over time affected BMD in the general population. Material and Methods Data was collected from patients who underwent dual-energy X-ray absorptiometry (DEXA) assessment between 2004 and 2011. Patients were included if they had multiple scans, including FM measurements. Our scanners limited these to scans of the lumbar spine. Linear regression analysis was performed to identify the relationship between changes in FM and BMD. Backwards stepwise linear regression analysis was performed to identify confounding factors, including sex, risk factors, previous fractures, and baseline BMI. Results In this study, 23,239 patients were included, of which 702 met the inclusion criteria. There were 609 (86%) females and 93 (13%) males with a mean age of 64.5 (SD 11.2) years at first scan. We identified a strong positive correlation between increasing FM and BMD between scans (coefficient 28.4; p<0.01; 95% CI, 26.6–30.1). Previous pelvic and femur fractures and a history of inflammatory diseases were also associated with increasing FM (p<0.05). This relationship was true regardless of patients BMI at their first scan. Conclusion These findings suggest that patients at high risk of fragility fractures should be encouraged to increase their FM as long as they are at a low risk for disease states related to high FM. PMID:27708960

  9. Best Practices for Dual-Energy X-ray Absorptiometry Measurement and Reporting: International Society for Clinical Densitometry Guidance.

    PubMed

    Lewiecki, E Michael; Binkley, Neil; Morgan, Sarah L; Shuhart, Christopher R; Camargos, Bruno Muzzi; Carey, John J; Gordon, Catherine M; Jankowski, Lawrence G; Lee, Joon-Kiong; Leslie, William D

    2016-01-01

    Dual-energy X-ray absorptiometry (DXA) is a technology that is widely used to diagnose osteoporosis, assess fracture risk, and monitor changes in bone mineral density (BMD). The clinical utility of DXA is highly dependent on the quality of the scan acquisition, analysis, and interpretation. Clinicians are best equipped to manage patients when BMD measurements are correct and interpretation follows well-established standards. Poor-quality acquisition, analysis, or interpretation of DXA data may mislead referring clinicians, resulting in unnecessary diagnostic evaluations, failure to evaluate when needed, inappropriate treatment, or failure to provide medical treatment, with potentially ineffective, harmful, or costly consequences. Misallocation of limited healthcare resources and poor treatment decisions can be minimized, and patient care optimized, through meticulous attention to DXA instrument calibration, data acquisition and analysis, interpretation, and reporting. This document from the International Society for Clinical Densitometry describes quality standards for BMD testing at DXA facilities worldwide to provide guidance for DXA supervisors, technologists, interpreters, and clinicians. High-quality DXA testing is necessary for correct diagnostic classification and optimal fracture risk assessment, and is essential for BMD monitoring.

  10. Best Practices for Dual-Energy X-ray Absorptiometry Measurement and Reporting: International Society for Clinical Densitometry Guidance.

    PubMed

    Lewiecki, E Michael; Binkley, Neil; Morgan, Sarah L; Shuhart, Christopher R; Camargos, Bruno Muzzi; Carey, John J; Gordon, Catherine M; Jankowski, Lawrence G; Lee, Joon-Kiong; Leslie, William D

    2016-01-01

    Dual-energy X-ray absorptiometry (DXA) is a technology that is widely used to diagnose osteoporosis, assess fracture risk, and monitor changes in bone mineral density (BMD). The clinical utility of DXA is highly dependent on the quality of the scan acquisition, analysis, and interpretation. Clinicians are best equipped to manage patients when BMD measurements are correct and interpretation follows well-established standards. Poor-quality acquisition, analysis, or interpretation of DXA data may mislead referring clinicians, resulting in unnecessary diagnostic evaluations, failure to evaluate when needed, inappropriate treatment, or failure to provide medical treatment, with potentially ineffective, harmful, or costly consequences. Misallocation of limited healthcare resources and poor treatment decisions can be minimized, and patient care optimized, through meticulous attention to DXA instrument calibration, data acquisition and analysis, interpretation, and reporting. This document from the International Society for Clinical Densitometry describes quality standards for BMD testing at DXA facilities worldwide to provide guidance for DXA supervisors, technologists, interpreters, and clinicians. High-quality DXA testing is necessary for correct diagnostic classification and optimal fracture risk assessment, and is essential for BMD monitoring. PMID:27020004

  11. Photon absorptiometry

    SciTech Connect

    Velchik, M.G.

    1987-01-01

    Recently, there has been a renewed interest in the detection and treatment of osteoporosis. This paper is a review of the merits and limitations of the various noninvasive modalities currently available for the measurement of bone mineral density with special emphasis placed upon the nuclear medicine techniques of single-photon and dual-photon absorptiometry. The clinicians should come away with an understanding of the relative advantages and disadvantages of photon absorptiometry and its optimal clinical application. 49 references.

  12. The impact of recent technological advances on the trueness and precision of DXA to assess body composition.

    PubMed

    Toombs, Rebecca J; Ducher, Gaele; Shepherd, John A; De Souza, Mary Jane

    2012-01-01

    The introduction of dual-energy X-ray absorptiometry (DXA) in the 1980s for the assessment of areal bone mineral density (BMD) greatly benefited the field of bone imaging and the ability to diagnose and monitor osteoporosis. The additional capability of DXA to differentiate between bone mineral, fat tissue, and lean tissue has contributed to its emergence as a popular tool to assess body composition. Throughout the past 2 decades, technological advancements such as the transition from the original pencil-beam densitometers to the most recent narrow fan-beam densitometers have allowed for faster scan times and better resolution. The majority of reports that have compared DXA-derived body composition measurements to the gold standard method of body composition appraisal, the four-compartment model, have observed significant differences with this criterion method; however, the extent to which the technological advancements of the DXA have impacted its ability to accurately assess body composition remains unclear. Thus, this paper reviews the evidence regarding the trueness and precision of DXA body composition measurements from the pencil-beam to the narrow fan-beam densitometers.

  13. Experimental validation of DXA-based finite element models for prediction of femoral strength.

    PubMed

    Dall'Ara, E; Eastell, R; Viceconti, M; Pahr, D; Yang, L

    2016-10-01

    Osteoporotic fractures are a major clinical problem and current diagnostic tools have an accuracy of only 50%. The aim of this study was to validate dual energy X-rays absorptiometry (DXA)-based finite element (FE) models to predict femoral strength in two loading configurations. Thirty-six pairs of fresh frozen human proximal femora were scanned with DXA and quantitative computed tomography (QCT). For each pair one femur was tested until failure in a one-legged standing configuration (STANCE) and one by replicating the position of the femur in a fall onto the greater trochanter (SIDE). Subject-specific 2D DXA-based linear FE models and 3D QCT-based nonlinear FE models were generated for each specimen and used to predict the measured femoral strength. The outcomes of the models were compared to standard DXA-based areal bone mineral density (aBMD) measurements. For the STANCE configuration the DXA-based FE models (R(2)=0.74, SEE=1473N) outperformed the best densitometric predictor (Neck_aBMD, R(2)=0.66, SEE=1687N) but not the QCT-based FE models (R(2)=0.80, SEE=1314N). For the SIDE configuration both QCT-based FE models (R(2)=0.85, SEE=455N) and DXA neck aBMD (R(2)=0.80, SEE=502N) outperformed DXA-based FE models (R(2)=0.77, SEE=529N). In both configurations the DXA-based FE model provided a good 1:1 agreement with the experimental data (CC=0.87 for SIDE and CC=0.86 for STANCE), with proper optimization of the failure criteria. In conclusion we found that the DXA-based FE models are a good predictor of femoral strength as compared with experimental data ex vivo. However, it remains to be investigated whether this novel approach can provide good predictions of the risk of fracture in vivo. PMID:27341287

  14. Dual-energy X-ray absorptiometry body composition in patients with secondary osteoporosis.

    PubMed

    Messina, Carmelo; Monaco, Cristian Giuseppe; Ulivieri, Fabio Massimo; Sardanelli, Francesco; Sconfienza, Luca Maria

    2016-08-01

    Due to the tight relationship between bone and soft tissues, there has been an increased interest in body composition assessment in patients with secondary osteoporosis as well as other pathological conditions. Dual-energy X-ray absorptiometry (DXA) is primarily devoted to the evaluation of bone mineral status, but continuous scientific advances of body composition software made DXA a rapid and easily available technique to assess body composition in terms of fat mass and lean mass. As a result, the International Society for Clinical Densitometry (ISCD) recently developed Official Positions regarding the use of this technique for body composition analysis. According to ISCD paper, indications are mainly limited to three conditions: HIV patients treated with antiretroviral agents associated with a risk of lipoatrophy; obese patients undergoing treatment for high weight loss; patients with sarcopenia or muscle weakness. Nevertheless, there are several other interesting clinical applications that were not included in the ISCD position paper, such as body composition assessment in patients undergoing organ transplantation, pulmonary disease as well as all those chronic condition that may lead to malnutrition. In conclusion, DXA body composition offers new diagnostic and research possibilities for a variety of diseases; due to its high reproducibility, DXA has also the potential to monitor body composition changes with pharmacological, nutritional or physic therapeutic interventions. ISCD addressed and recommended a list of clinical condition, but the crescent availability of DXA scans and software improvements may open the use of DXA to other indication in the next future. This article provides an overview of DXA body composition indications in the management of secondary osteoporosis and other clinical indications in adults. PMID:27048946

  15. In vivo precision of dual-energy X-ray absorptiometry-derived hip structural analysis in adults.

    PubMed

    Hind, Karen; Oldroyd, Brian; Prajapati, Anup; Rhodes, Laura

    2012-01-01

    Precision is integral to the monitoring of bone mineral density (BMD) change using dual-energy X-ray absorptiometry (DXA). Hip structural analysis (HSA) is a relatively recent method of assessing cross-sectional geometrical strength from the 2-dimensional images produced by DXA scans. By performing serial scans, we evaluated the in vivo precision of DXA-derived HSA in adults using a GE Lunar iDXA absorptiometer (GE Medical Systems, Madison, WI) in males and females (n=42), mean age of 34.5 (standard deviation [SD]: 8.5; range: 19.3-52.6)yr with a heterogeneous sample. Two consecutive intelligent DXA (iDXA) scans with repositioning of both femurs were conducted for each participant. The coefficient of variation, root-mean-square (RMS) averages of SD, and hence the least significant change (95%) were calculated. We found a high level of precision for BMD measurements of both the total hip and femoral neck, with RMS-SD=0.006 and 0.010 g/cm(2) and percent coefficient of variation (%CV)=0.52% and 0.94%, respectively. We also found good precision for HSA-derived geometrical properties, including sectional modulus, cross-sectional moment of inertia, and cross-sectional area, with %CV (average of the left and right sides) at 4.48%, 3.78%, and 3.13%, respectively. Precision was poorer for buckling ratio and femoral strength index with %CV 28.5% and 9.25%, respectively. The iDXA provides high precision for BMD measurements and with varying levels of precision for HSA geometrical properties.

  16. Influence of different DXA acquisition modes on monitoring the changes in bone mineral density after hip resurfacing arthroplasty.

    PubMed

    Hakulinen, Mikko A; Borg, Håkan; Häkkinen, Arja; Parviainen, Tapani; Kiviranta, Ilkka; Jurvelin, Jukka S

    2012-01-01

    Dual-energy X-ray absorptiometry (DXA) is a technique enabling the measurement of bone mineral density (BMD) around prostheses after hip resurfacing arthroplasty (HRA). In this study, we evaluated the consistency of different DXA acquisition modes with 33 patients who had undergone HRA. Patients were scanned with DXA immediately after surgery and at 3-, 6-, and 12-mo time points. All the patients were scanned with dual femur and orthopedic hip acquisition modes and analyzed using 10-region ROI model. With both acquisition modes, a statistically significant decrease (p<0.05, Wilcoxon's test) in BMD at 3mo was revealed in 3 ROIs, located to upper and lateral upper femur. Both acquisition modes detected similarly (p<0.01) preservation of the femoral bone stock within 12mo in all but 1 ROI. The applied acquisition protocols involved the use of different footplates for hip fixation. Because the differences between acquisition modes ranged between +1.6% and -7.1% and the reproducibility of BMD values can vary by as much as 28% due to hip rotation, it is proposed that both dual femur and orthopedic hip acquisition modes can be used to monitor the changes in BMD after HRA. However, the same hip rotation is recommended for all DXA measurements.

  17. Relationship among MRTA, DXA, and QUS.

    PubMed

    Djokoto, Christina; Tomlinson, George; Waldman, Stephen; Grynpas, Marc; Cheung, Angela M

    2004-01-01

    Dual-energy X-ray absorptiometry (DXA) and quantitative ultrasound (QUS) are the accepted modalities for the evaluation of fracture risk in the clinical setting. However, neither method provides a direct measurement of bone mechanics. In this study, we investigated a prototype device, known as a mechanical response tissue analyzer (MRTA), which provides direct mechanical measurements of mechanical properties of bone. A total of 56 healthy volunteers (20 men and 36 women) between the ages of 18 and 83 were recruited. The MRTA was used to measure the cross-sectional bending stiffness (EI) of the ulna bone. Axial speed of sound (SOS) at the ulna bone was determined by QUS; bone mineral content (BMC) and bone mineral density (BMD) were determined by DXA. Correlations, regression analysis, and analyses of variance (ANOVAs) were used to compare the three modalities. These analyses revealed that although there are strong linear relationships among the data collected by the various technologies, the bone properties reflected by MRTA are not fully explained by DXA and QUS. We conclude that the total information conveyed by MRTA measurements is unique. Further research is needed to delineate the different qualities of bone strength that are captured by MRTA, but not by DXA or QUS. PMID:15618607

  18. Relationship among MRTA, DXA, and QUS.

    PubMed

    Djokoto, Christina; Tomlinson, George; Waldman, Stephen; Grynpas, Marc; Cheung, Angela M

    2004-01-01

    Dual-energy X-ray absorptiometry (DXA) and quantitative ultrasound (QUS) are the accepted modalities for the evaluation of fracture risk in the clinical setting. However, neither method provides a direct measurement of bone mechanics. In this study, we investigated a prototype device, known as a mechanical response tissue analyzer (MRTA), which provides direct mechanical measurements of mechanical properties of bone. A total of 56 healthy volunteers (20 men and 36 women) between the ages of 18 and 83 were recruited. The MRTA was used to measure the cross-sectional bending stiffness (EI) of the ulna bone. Axial speed of sound (SOS) at the ulna bone was determined by QUS; bone mineral content (BMC) and bone mineral density (BMD) were determined by DXA. Correlations, regression analysis, and analyses of variance (ANOVAs) were used to compare the three modalities. These analyses revealed that although there are strong linear relationships among the data collected by the various technologies, the bone properties reflected by MRTA are not fully explained by DXA and QUS. We conclude that the total information conveyed by MRTA measurements is unique. Further research is needed to delineate the different qualities of bone strength that are captured by MRTA, but not by DXA or QUS.

  19. Quantitative Comparison of 2 Dual-Energy X-ray Absorptiometry Systems in Assessing Body Composition and Bone Mineral Measurements.

    PubMed

    Xu, Wenhua; Chafi, Hatim; Guo, Beibei; Heymsfield, Steven B; Murray, Kori B; Zheng, Jolene; Jia, Guang

    2016-01-01

    Dual-energy X-ray absorptiometry (DXA) is widely used in body composition measurement and evaluation. Because of its numerous applications, the probability of instrument discrepancies has increased dramatically. This study quantitatively compares 2 different DXA systems. In this study, 96 subjects (60 female and 36 male, aged 19-82 years) were recruited and scanned using a General Electric Lunar iDXA and a Hologic Discovery scanner. Four measurements (percent fat, total mass, bone mineral density [BMD], and bone mineral content [BMC]) were quantitatively compared in the whole body and in specific anatomic regions (arms, legs, trunk, android, gynoid, head, ribs, and pelvis). A simple linear regression of each measurement was performed to examine the correlation between the 2 systems. Percent fat, total mass, BMC, and BMD were highly correlated between the 2 DXA systems, with correlation r values greater than 0.854 for both the whole body and the individual anatomic regions except for BMC and BMD in ribs. The high correlation between the 2 DXA systems with systematic differences enabled development of calibration equations for extending the multisystem measurements to advanced quantitative analyses. PMID:26206525

  20. The use of dual-energy x-ray absorptiometry in animals.

    PubMed

    Grier, S J; Turner, A S; Alvis, M R

    1996-01-01

    The use of dual-energy absorptiometry (DXA) to measure bone mineral content (BMC) and bone mineral density (BMD) is widespread in humans and has been adapted to animals because of the need to examine bone and body composition in longitudinal studies. In this review, the indications and techniques for DXA in small-sized animals (rodents, cats, and rabbits) and large-sized animals (dogs, swine, nonhuman primates, sheep, and horses) are discussed. Now that software has been developed for measuring BMD in small laboratory animals, the most frequent use of DXA in animals is in rats. An ultrahigh-resolution mode of acquisition is used for their small bones but also is necessary for other small-sized animals such as rabbits and cats. In larger-sized animals such as dogs, pigs, and sheep, software used in humans has been adapted successfully to measure BMC/BMD and body composition. The human spine and left and right hip protocols are adapted easily to animals of this size, and the software for body composition has been adapted to dogs. Measurement of bone mass around metallic implants is possible in animals and most studies have involved dogs. To ensure precision of DXA in the noninvasive measurement of BMD in animals, attention to positioning and ability of the operator to define the same region of interest using clearly defined anatomical landmarks on the scan image cannot be overemphasized. This is one of the essential requirements for successful densitometry in animals. PMID:8850365

  1. First all-solid pediatric phantom for dual X-ray absorptiometry measurements in infants.

    PubMed

    Picaud, Jean-Charles; Duboeuf, François; Vey-Marty, Vey; Delams, Pierre; Claris, Oliver; Salle, Bernard-Louis; Rigo, Jacques

    2003-01-01

    Manufacturer-supplied lumbar spine phantoms are normally used for quality control of dual X-ray absorptiometry (DXA) instruments. Presently, there is no pediatric phantom for whole-body mineralization and softtissue composition DXA measurements. We designed blocks of acrylic (for fat mass), polyvinyl chloride (for lean mass), and aluminum (for bone mass) whose combination provides five whole-body phantoms ("Inphants") that mimic body weight and composition during the first year of life and help solve problems that require repeated scans in stable conditions. Inphants were scanned using an Hologic QDR 2000. Comparisons were made between values obtained with and without the table pad, using infant software. Then we compared data obtained using infant and adult softwares successively in the same phantoms. The table pad significantly influenced DXA measurements. We observed significant differences in fat mass (p = 0.04) and lean mass (p = 0.03) with the smaller Inphant (3 kg) and in bone mineral content (BMC) (p = 0.02) with the larger Inphant (13 kg). BMC was three to five times lower with adult than with infant software. Adult software yielded systematically significantly lower fat masses but higher lean masses than infant software. Because there was no overlap with larger Inphants, we calculated conversion formulae between values of infant and adult software. The results suggest guidelines for scan acquisition and analysis in young subjects. PMID:12665698

  2. Comparison of Anthropometry to Dual Energy X-Ray Absorptiometry: A New Prediction Equation for Women

    ERIC Educational Resources Information Center

    Ball, Stephen; Swan, Pamela D.; DeSimone, Rosemarie

    2004-01-01

    The purpose of this study was to assess the accuracy of three recommended anthropometric equations for women and then develop an updated prediction equation using dual energy x-ray absorptiometry (DXA). The percentage of body fat (%BF) by anthropometry was significantly correlated (r = .896-. 929; p [is less than] .01) with DXA, but each equation…

  3. Ethnic Bias in Anthropometric Estimates of DXA Abdominal Fat: the TIGER Study

    PubMed Central

    O’Connor, Daniel P.; Bray, Molly S.; McFarlin, Brian K.; Ellis, Kenneth J.; Sailors, Mary H.; Jackson, Andrew S.

    2011-01-01

    Background/Introduction The purpose of this study was to examine race/ethnicity bias of using waist circumference (WC) to estimate abdominal fat. Methods A total of 771 females and 484 males (17–35 y) were tested one to three times during a prescribed 30-week aerobic exercise program. The race/ethnicity distribution for women was: non-Hispanic white (NHW), 29%; Hispanic, 25%; African-American (AA), 35%; Asian-Indian, 3%; and Asian, 8%. The distribution for men was: NHW, 37%; Hispanic, 26%; AA 22%; Asian-Indian, 5%; and Asian, 10%. Abdominal fat (L1 to L5) was estimated from whole body scanning using dual energy x-ray absorptiometry (DXA Abd-Fat). Results DXA Abd-Fat varied by race/ethnicity after accounting for WC and height in both women and men. The increase in DXA Abd-Fat per increase in WC was lower in the Asian and Asian-Indian women than in the other women. The increase in DXA Abd-Fat per increase in WC was higher in the AA men and lower in the Asian-Indian men than in the other men. These differential race/ethnicity effects were most notable when WC exceeded 90 cm in the women and 100 cm in the men, values which are consistent with current definitions of abdominal obesity in the United States. Conclusions Prediction equations for abdominal fat using WC that do not account for race/ethnicity group provide biased estimates. These results may affect assessment of disease risk from abdominal obesity among racial/ethnic groups. PMID:21364481

  4. Validation of Dual Energy X-Ray Absorptiometry Measures of Abdominal Fat by Comparison with Magnetic Resonance Imaging in an Indian Population

    PubMed Central

    Taylor, Amy E.; Kuper, Hannah; Varma, Ravi D.; Wells, Jonathan C.; Bell, Jimmy D.; V.Radhakrishna, K.; Kulkarni, Bharati; Kinra, Sanjay; Timpson, Nicholas J.; Ebrahim, Shah; Smith, George Davey; Ben-Shlomo, Yoav

    2012-01-01

    Objective Abdominal adiposity is an important risk factor for diabetes and cardiovascular disease in Indians. Dual energy X-ray absorptiometry (DXA) can be used to determine abdominal fat depots, being more accessible and less costly than gold standard measures such as magnetic resonance imaging (MRI). DXA has not been fully validated for use in South Asians. Here, we determined the accuracy of DXA for measurement of abdominal fat in an Indian population by comparison with MRI. Design 146 males and females (age range 18–74, BMI range 15–46 kg/m2) from Hyderabad, India underwent whole body DXA scans on a Hologic Discovery A scanner, from which fat mass in two abdominal regions was calculated, from the L1 to L4 vertebrae (L1L4) and from the L2 to L4 vertebrae (L2L4). Abdominal MRI scans (axial T1-weighted spin echo images) were taken, from which adipose tissue volumes were calculated for the same regions. Results Intra-class correlation coefficients between DXA and MRI measures of abdominal fat were high (0.98 for both regions). Although at the level of the individual, differences between DXA and MRI could be large (95% of DXA measures were between 0.8 and 1.4 times MRI measures), at the sample level, DXA only slightly overestimated MRI measures of abdominal fat mass (mean difference in L1L4 region: 2% (95% CI:0%, 5%), mean difference in L2L4 region:4% (95% CI: 1%, 7%)). There was evidence of a proportional bias in the association between DXA and MRI (correlation between difference and mean −0.3), with overestimation by DXA greater in individuals with less abdominal fat (mean bias in leaner half of sample was 6% for L1L4 (95%CI: 2, 11%) and 7% for L2L4 (95% CI:3,12%). Conclusions DXA measures of abdominal fat are suitable for use in Indian populations and provide a good indication of abdominal adiposity at the population level. PMID:23272086

  5. 3D bone mineral density distribution and shape reconstruction of the proximal femur from a single simulated DXA image: an in vitro study

    NASA Astrophysics Data System (ADS)

    Whitmarsh, Tristan; Humbert, Ludovic; De Craene, Mathieu; del Río Barquero, Luis M.; Fritscher, Karl; Schubert, Rainer; Eckstein, Felix; Link, Thomas; Frangi, Alejandro F.

    2010-03-01

    Area Bone Mineral Density (aBMD) measured by Dual-energy X-ray Absorptiometry (DXA) is an established criterion in the evaluation of hip fracture risk. The evaluation from these planar images, however, is limited to 2D while it has been shown that proper 3D assessment of both the shape and the Bone Mineral Density (BMD) distribution improves the fracture risk estimation. In this work we present a method to reconstruct both the 3D bone shape and 3D BMD distribution of the proximal femur from a single DXA image. A statistical model of shape and a separate statistical model of the BMD distribution were automatically constructed from a set of Quantitative Computed Tomography (QCT) scans. The reconstruction method incorporates a fully automatic intensity based 3D-2D registration process, maximizing the similarity between the DXA and a digitally reconstructed radiograph of the combined model. For the construction of the models, an in vitro dataset of QCT scans of 60 anatomical specimens was used. To evaluate the reconstruction accuracy, experiments were performed on simulated DXA images from the QCT scans of 30 anatomical specimens. Comparisons between the reconstructions and the same subject QCT scans showed a mean shape accuracy of 1.2mm, and a mean density error of 81mg/cm3. The results show that this method is capable of accurately reconstructing both the 3D shape and 3D BMD distribution of the proximal femur from DXA images used in clinical routine, potentially improving the diagnosis of osteoporosis and fracture risk assessments at a low radiation dose and low cost.

  6. Precision Error in Dual-Energy X-Ray Absorptiometry Body Composition Measurements in Elite Male Rugby League Players.

    PubMed

    Barlow, Matthew J; Oldroyd, Brian; Smith, Debbie; Lees, Matthew J; Brightmore, Amy; Till, Kevin; Jones, Benjamin; Hind, Karen

    2015-01-01

    Body composition analysis using dual-energy X-ray absorptiometry (DXA) is becoming increasingly popular in both clinical and sports science settings. Obesity, characterized by high fat mass (FM), is associated with larger precision errors; however, precision error for athletic groups with high levels of lean mass (LM) are unclear. Total (TB) and regional (limbs and trunk) body composition were determined from 2 consecutive total body scans (GE Lunar iDXA) with re-positioning in 45 elite male rugby league players (age: 21.8 ± 5.4 yr; body mass index: 27.8 ± 2.5 kg m(-1)). The root mean squared standard deviation (percentage co-efficient of variation) were TB bone mineral content: 24g (1.7%), TB LM: 321 g (1.6%), and TB FM: 280 g (2.3%). Regional precision values were superior for measurements of bone mineral content: 4.7-16.3 g (1.7-2.1%) and LM: 137-402 g (2.0-2.4%), than for FM: 63-299 g (3.1-4.1%). Precision error of DXA body composition measurements in elite male rugby players is higher than those reported elsewhere for normal adult populations and similar to those reported in those who are obese. It is advised that caution is applied when interpreting longitudinal DXA-derived body composition measurements in male rugby players and population-specific least significant change should be adopted. PMID:26072358

  7. Effect of ¹⁸F-FDG administration on measurements of bone mineral density and body composition by dual-energy X-ray absorptiometry.

    PubMed

    Kim, Dae-Weung; Kim, Woo Hyoung; Kim, Myoung Hyoun; Kim, Seong Su; Mo, Eun Hee; Lee, Chun Ho; Kim, Chang Guhn

    2013-01-01

    The purpose of this study was to determine whether antecedent administration of ¹⁸F-fluorodeoxyglucose (FDG) used in positron emission tomography (PET) scanning results in corruption of bone mineral density (BMD) and body composition measured by dual-energy X-ray absorptiometry (DXA) system. DXA measurements of BMD and body composition had been performed twice, before and after ¹⁸F-FDG PET scan in 30 patients. The comparison of pre-values and post-values of all BMD values showed a decrease after the injection. However, only the decrease of whole-body BMD (WB-BMD) was statistically significant (p < 0.05). Whole-body fat mass had increased and whole-body lean body mass had decreased after the injection of ¹⁸F-FDG, and these were statistically significant (p < 0.05). There is statistically significant correlation between the injected ¹⁸F-FDG dose and a decrease of WB-BMD (r = -0.405; p < 0.05). The findings of this study suggest that when both ¹⁸F-FDG PET and DXA measurements for whole-body composition are performed in close-time proximity, ¹⁸F-FDG PET scans should follow the DXA measurement. Otherwise, BMD measurements of total femur or lumbar spine could be followed by ¹⁸F-FDG PET in close-time proximity. PMID:23562363

  8. Effect of ¹⁸F-FDG administration on measurements of bone mineral density and body composition by dual-energy X-ray absorptiometry.

    PubMed

    Kim, Dae-Weung; Kim, Woo Hyoung; Kim, Myoung Hyoun; Kim, Seong Su; Mo, Eun Hee; Lee, Chun Ho; Kim, Chang Guhn

    2013-01-01

    The purpose of this study was to determine whether antecedent administration of ¹⁸F-fluorodeoxyglucose (FDG) used in positron emission tomography (PET) scanning results in corruption of bone mineral density (BMD) and body composition measured by dual-energy X-ray absorptiometry (DXA) system. DXA measurements of BMD and body composition had been performed twice, before and after ¹⁸F-FDG PET scan in 30 patients. The comparison of pre-values and post-values of all BMD values showed a decrease after the injection. However, only the decrease of whole-body BMD (WB-BMD) was statistically significant (p < 0.05). Whole-body fat mass had increased and whole-body lean body mass had decreased after the injection of ¹⁸F-FDG, and these were statistically significant (p < 0.05). There is statistically significant correlation between the injected ¹⁸F-FDG dose and a decrease of WB-BMD (r = -0.405; p < 0.05). The findings of this study suggest that when both ¹⁸F-FDG PET and DXA measurements for whole-body composition are performed in close-time proximity, ¹⁸F-FDG PET scans should follow the DXA measurement. Otherwise, BMD measurements of total femur or lumbar spine could be followed by ¹⁸F-FDG PET in close-time proximity.

  9. In vivo precision of the GE Lunar iDXA densitometer for the measurement of total body composition and fat distribution in adults.

    PubMed

    Hind, K; Oldroyd, B; Truscott, J G

    2011-01-01

    In vivo precision for body composition measurements using dual energy X-ray absorptiometry (DXA; GE Lunar iDXA, GE Healthcare, Bucks, UK) was evaluated in 52 men and women, aged 34.8 (s.d. 8.4; range 20.1-50.5) years, body mass index (25.8 kg/m(2); range 16.7-42.7 kg/m(2)). Two consecutive total body scans (with re-positioning) were conducted. Precision was excellent for all measurements, particularly for total body bone mineral content and lean tissue mass (root mean square 0.015 and 0.244 kg; coefficients of variation (CV) 0.6 and 0.5%, respectively). Precision error was CV 0.82% for total fat mass and 0.86% for percentage fat. Precision was better for gynoid (root mean square 0.397 kg; CV 0.96%) than for android fat distribution (root mean square 0.780 kg, CV 2.32%). There was good agreement between consecutive measurements for all measurements (slope (s.e.) 0.993-1.002; all R(2) = 0.99). The Lunar iDXA provided excellent precision for total body composition measurements. Research into the effect of body size on the precision of DXA body fat distribution measurements is required.

  10. Comparison of visceral fat mass measurement by dual-X-ray absorptiometry and magnetic resonance imaging in a multiethnic cohort: the Dallas Heart Study

    PubMed Central

    Neeland, I J; Grundy, S M; Li, X; Adams-Huet, B; Vega, G L

    2016-01-01

    Background/Objectives: Visceral adipose tissue (VAT) mass, a risk factor for cardiometabolic complications of obesity, is usually measured by magnetic resonance imaging (MRI) but this method is not practical in a clinical setting. In contrast, measurement of VAT by dual-x-ray absorptiometry (DXA) appears to circumvent the limitations of MRI. In this study, we compared measurements of VAT mass by MRI and DXA in the large, multiethnic cohort of the Dallas Heart Study (DHS). Subjects/Methods: About 2689 DHS participants underwent paired measurement of VAT by MRI and DXA. Sex-stratified analyses were performed to evaluate the correlation and agreement between DXA and MRI. Model validation was performed using bootstrapping and inter-reader variability was assessed. Results: Mean age of the cohort was 44 years, with 55% female, 48% Black and 75% overweight/obese participants. Regression analysis showed a linear relationship between DXA and MRI with R2=0.82 (95% confidence interval (CI) 0.81–0.84) for females and R2=0.86 (95% CI 0.85–0.88) for males. Mean difference between methods was 0.01 kg for females and 0.09 kg for males. Bland–Altman analysis showed that DXA tended to modestly underestimate VAT compared with MRI at lower VAT levels and overestimate it compared with MRI at higher VAT levels. Results were consistent in analyses stratified by race, body mass index status, waist girth and body fat. Inter-individual reader correlation among 50 randomly selected scans was excellent (inter-class correlation coefficient=0.997). Conclusions: VAT mass quantification by DXA was both accurate and valid among a large, multiethnic cohort within a wide range of body fatness. Further studies including repeat assessments over time will help determine its long-term applicability. PMID:27428873

  11. Guidelines for Dual Energy X-Ray Absorptiometry Analysis of Trabecular Bone-Rich Regions in Mice: Improved Precision, Accuracy, and Sensitivity for Assessing Longitudinal Bone Changes.

    PubMed

    Shi, Jiayu; Lee, Soonchul; Uyeda, Michael; Tanjaya, Justine; Kim, Jong Kil; Pan, Hsin Chuan; Reese, Patricia; Stodieck, Louis; Lin, Andy; Ting, Kang; Kwak, Jin Hee; Soo, Chia

    2016-05-01

    Trabecular bone is frequently studied in osteoporosis research because changes in trabecular bone are the most common cause of osteoporotic fractures. Dual energy X-ray absorptiometry (DXA) analysis specific to trabecular bone-rich regions is crucial to longitudinal osteoporosis research. The purpose of this study is to define a novel method for accurately analyzing trabecular bone-rich regions in mice via DXA. This method will be utilized to analyze scans obtained from the International Space Station in an upcoming study of microgravity-induced bone loss. Thirty 12-week-old BALB/c mice were studied. The novel method was developed by preanalyzing trabecular bone-rich sites in the distal femur, proximal tibia, and lumbar vertebrae via high-resolution X-ray imaging followed by DXA and micro-computed tomography (micro-CT) analyses. The key DXA steps described by the novel method were (1) proper mouse positioning, (2) region of interest (ROI) sizing, and (3) ROI positioning. The precision of the new method was assessed by reliability tests and a 14-week longitudinal study. The bone mineral content (BMC) data from DXA was then compared to the BMC data from micro-CT to assess accuracy. Bone mineral density (BMD) intra-class correlation coefficients of the new method ranging from 0.743 to 0.945 and Levene's test showing that there was significantly lower variances of data generated by new method both verified its consistency. By new method, a Bland-Altman plot displayed good agreement between DXA BMC and micro-CT BMC for all sites and they were strongly correlated at the distal femur and proximal tibia (r=0.846, p<0.01; r=0.879, p<0.01, respectively). The results suggest that the novel method for site-specific analysis of trabecular bone-rich regions in mice via DXA yields more precise, accurate, and repeatable BMD measurements than the conventional method.

  12. Guidelines for Dual Energy X-Ray Absorptiometry Analysis of Trabecular Bone-Rich Regions in Mice: Improved Precision, Accuracy, and Sensitivity for Assessing Longitudinal Bone Changes.

    PubMed

    Shi, Jiayu; Lee, Soonchul; Uyeda, Michael; Tanjaya, Justine; Kim, Jong Kil; Pan, Hsin Chuan; Reese, Patricia; Stodieck, Louis; Lin, Andy; Ting, Kang; Kwak, Jin Hee; Soo, Chia

    2016-05-01

    Trabecular bone is frequently studied in osteoporosis research because changes in trabecular bone are the most common cause of osteoporotic fractures. Dual energy X-ray absorptiometry (DXA) analysis specific to trabecular bone-rich regions is crucial to longitudinal osteoporosis research. The purpose of this study is to define a novel method for accurately analyzing trabecular bone-rich regions in mice via DXA. This method will be utilized to analyze scans obtained from the International Space Station in an upcoming study of microgravity-induced bone loss. Thirty 12-week-old BALB/c mice were studied. The novel method was developed by preanalyzing trabecular bone-rich sites in the distal femur, proximal tibia, and lumbar vertebrae via high-resolution X-ray imaging followed by DXA and micro-computed tomography (micro-CT) analyses. The key DXA steps described by the novel method were (1) proper mouse positioning, (2) region of interest (ROI) sizing, and (3) ROI positioning. The precision of the new method was assessed by reliability tests and a 14-week longitudinal study. The bone mineral content (BMC) data from DXA was then compared to the BMC data from micro-CT to assess accuracy. Bone mineral density (BMD) intra-class correlation coefficients of the new method ranging from 0.743 to 0.945 and Levene's test showing that there was significantly lower variances of data generated by new method both verified its consistency. By new method, a Bland-Altman plot displayed good agreement between DXA BMC and micro-CT BMC for all sites and they were strongly correlated at the distal femur and proximal tibia (r=0.846, p<0.01; r=0.879, p<0.01, respectively). The results suggest that the novel method for site-specific analysis of trabecular bone-rich regions in mice via DXA yields more precise, accurate, and repeatable BMD measurements than the conventional method. PMID:26956416

  13. Measurement precision of body composition variables in elite wheelchair athletes, using dual-energy X-ray absorptiometry.

    PubMed

    Keil, Mhairi; Totosy de Zepetnek, Julia O; Brooke-Wavell, Katherine; Goosey-Tolfrey, Victoria L

    2016-01-01

    The purpose of this study was to assess the reproducibility of body composition measurements by dual-energy X-ray absorptiometry (DXA) in 12 elite male wheelchair basketball players (age 31 ± 7 years, BMI 21 ± 2 kg/m(2) and onset of disability 25 ± 9 years). Two whole body scans were performed on each participant in the supine position on the same day, using Lunar Prodigy Advance DXA (GE Lunar, Madison, WI, USA). Participants dismounted from the scanning table and were repositioned in-between the first and second scan. Whole body coefficient of variation (CV) values for bone mineral content (BMC), fat mass (FM) and soft tissue lean mass (LTM) were all <2.0%. With the exclusion of arm FM (CV = 7.8%), CV values ranged from 0.1 to 3.7% for all total body and segmental measurements of BMC, FM and LTM. The least significant change that can be attributed to the effect of treatment intervention in an individual is 1.0 kg, 1.1 kg, 0.12 kg for FM, LTM, and BMC, respectively. This information can be used to determine meaningful changes in body composition when assessed using the same methods longitudinally. Whilst there may be challenges in the correct positioning of an individual with disability that can introduce greater measurement error, DXA is a highly reproducible technique in the estimation of total and regional body composition of elite wheelchair basketball athletes.

  14. Assessment of adiposity in psoriatic patients by dual energy X-ray absorptiometry compared to conventional methods*

    PubMed Central

    Diniz, Michelle dos Santos; Bavoso, Nádia Couto; Kakehasi, Adriana Maria; Lauria, Márcio Weissheimer; Soares, Maria Marta Sarquis; Machado-Pinto, Jackson

    2016-01-01

    BACKGROUND Obesity is considered a chronic low-grade inflammatory disease that shares mediators of inflammation with psoriasis, such as TNF-α and IL-6. The relationship between these two conditions involves factors such as predisposition and response to therapy, in addition to an association with cardiovascular disease. OBJECTIVES The aim of the present study was to investigate the prevalence of adiposity as determined by body mass index (BMI), waist circumference (WC), and dual energy X-ray absorptiometry (DXA) evaluation in patients with psoriasis. METHODS BMI, WC and body composition by DXA were measured in 42 psoriatic patients without joint complaints and in 41 control patients using standard procedures. In the comparison between cases and controls, we used Pearson’s Χ2 test or Fisher’s exact test, and the nonparametric Mann-Whitney test. The difference between the diverse classification methods for obesity was evaluated using McNemar’s test. To test the level of agreement between those variables, we used the weighted kappa coefficient. RESULTS There was no difference in the prevalence of obesity among cases and controls. Both BMI and WC had low agreement with measures of body fat evaluated by DXA. With the use of DXA scanning, prevalence of overweight and obesity in patients with psoriasis was 83.3%, which constitutes a strong evidence of the need for intervention on this metabolic parameter. CONCLUSION Dual energy X-ray absorptiometry was more capable of identifying obesity compared with BMI and WC both in psoriatic and control patients. PMID:27192512

  15. Body Fat Mass Assessment: A Comparison between an Ultrasound-Based Device and a Discovery A Model of DXA

    PubMed Central

    Pineau, Jean-Claude; Lalys, Loïc; Pellegrini, Massimo; Battistini, Nino Carlo

    2013-01-01

    Objective. To examine measurement of body composition by ultrasound compared with a reference technique:dual energy X-ray absorptiometry (DXA). We evaluated the accuracy of a portable ultrasound-based device in estimating total body fat mass with those assessed by DXA in adult. Methods. Body fat mass has been estimated using a portable ultrasound-based device in comparison with a contemporary reference DXA apparatus: the Hologic Discovery A. Anthropometric data has been assessed in order to maximize the output of the software associated with the ultrasound-based device. A cross-validation between ultrasound technique (US) and DXA was developed in this study. Total body fat mass estimated by ultrasound was compared with this DXA model in a sample of 83 women and 41 men. Results. Ultrasound technique (US) of body fat (BF) was better correlated with DXA in both women (r2 = 0.97, P < 0.01) and men (r2 = 0.92, P < 0.01) with standard errors of estimates (SEE) being 2.1 kg and 2.2 kg, respectively. Conclusion. The use of a portable device based on a US produced a very accurate BF estimate in relation to DXA reference technique. As DXA absorptiometry techniques are not interchangeable, the use of our ultrasound-based device needs to be recalibrated on a more contemporary DXA. PMID:24575315

  16. Improvement in the accuracy of dual energy x-ray absorptiometry for whole body and regional analysis of body composition: validation using piglets and methodologic considerations in infants.

    PubMed

    Brunton, J A; Weiler, H A; Atkinson, S A

    1997-04-01

    Previously, we conducted dual energy x-ray absorptiometry (DXA) (Hologic QDR-1000/W) scans and carcass analysis of piglets to evaluate the Pediatric Whole Body software (PedWB) (V5.35) for use in infants. A software upgrade designed for infant whole body (InfWB) (V5.56) led to a reassessment of DXA by: 1) reanalysis of the original scans using InfWB software and 2) comparison of InfWB-estimates of bone mineral content (BMC) and lean and fat mass with chemical analysis. Other assessments included 1) methods of regional analysis and 2) artifacts and the Infant Table Pad in the scan field. The mean coefficients of variation for InfWB whole body measures in small piglets (n = 10, weight 1575 +/- 73 g) and large piglets (n = 10, weight 5894 +/- 208 g) were less than 2.6% except for fat mass which was higher (8.0% versus 6.3% and 6.6% versus 3.5%, respectively) compared with PedWB. In large piglets InfWB produced good estimates of BMC, lean and fat masses. In small piglets, fat mass by InfWB was correlated with chemical analysis, but not by PedWB. There was improvement in the estimation of BMC with InfWB, from 27 +/- 2.2 g to 32 +/- 2.3 g (carcass ash = 38 +/- 3.3 g). Femur BMC analysis by InfWB was precise and was accurate when compared with chemical analysis. Artifacts in the DXA scan field (diapers and blankets) resulted in an increase of the DXA-estimated fat and lean masses. The Infant Table Pad increased the estimate of fat mass in a small piglet by 50%, thus further study is required before it is used routinely. Improvements of the DXA technology have resulted in a more accurate tool, if scanning procedures are carefully implemented. PMID:9098865

  17. Estimates of volumetric bone density from projectional measurements improve the discriminatory capability of dual X-ray absorptiometry

    NASA Technical Reports Server (NTRS)

    Jergas, M.; Breitenseher, M.; Gluer, C. C.; Yu, W.; Genant, H. K.

    1995-01-01

    To determine whether estimates of volumetric bone density from projectional scans of the lumbar spine have weaker associations with height and weight and stronger associations with prevalent vertebral fractures than standard projectional bone mineral density (BMD) and bone mineral content (BMC), we obtained posteroanterior (PA) dual X-ray absorptiometry (DXA), lateral supine DXA (Hologic QDR 2000), and quantitative computed tomography (QCT, GE 9800 scanner) in 260 postmenopausal women enrolled in two trials of treatment for osteoporosis. In 223 women, all vertebral levels, i.e., L2-L4 in the DXA scan and L1-L3 in the QCT scan, could be evaluated. Fifty-five women were diagnosed as having at least one mild fracture (age 67.9 +/- 6.5 years) and 168 women did not have any fractures (age 62.3 +/- 6.9 years). We derived three estimates of "volumetric bone density" from PA DXA (BMAD, BMAD*, and BMD*) and three from paired PA and lateral DXA (WA BMD, WA BMDHol, and eVBMD). While PA BMC and PA BMD were significantly correlated with height (r = 0.49 and r = 0.28) or weight (r = 0.38 and r = 0.37), QCT and the volumetric bone density estimates from paired PA and lateral scans were not (r = -0.083 to r = 0.050). BMAD, BMAD*, and BMD* correlated with weight but not height. The associations with vertebral fracture were stronger for QCT (odds ratio [QR] = 3.17; 95% confidence interval [CI] = 1.90-5.27), eVBMD (OR = 2.87; CI 1.80-4.57), WA BMDHol (OR = 2.86; CI 1.80-4.55) and WA-BMD (OR = 2.77; CI 1.75-4.39) than for BMAD*/BMD* (OR = 2.03; CI 1.32-3.12), BMAD (OR = 1.68; CI 1.14-2.48), lateral BMD (OR = 1.88; CI 1.28-2.77), standard PA BMD (OR = 1.47; CI 1.02-2.13) or PA BMC (OR = 1.22; CI 0.86-1.74). The areas under the receiver operating characteristic (ROC) curves for QCT and all estimates of volumetric BMD were significantly higher compared with standard PA BMD and PA BMC. We conclude that, like QCT, estimates of volumetric bone density from paired PA and lateral scans are

  18. Generalized equations for estimating DXA percent fat of diverse young women and men: The Tiger Study

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Popular generalized equations for estimating percent body fat (BF%) developed with cross-sectional data are biased when applied to racially/ethnically diverse populations. We developed accurate anthropometric models to estimate dual-energy x-ray absorptiometry BF% (DXA-BF%) that can be generalized t...

  19. Suspension criteria for dual energy X ray absorptiometry.

    PubMed

    McLean, I D

    2013-02-01

    The use of dual-energy X-ray absorptiometry (DXA) units primarily for the assessment of fracture risk and in the diagnosis of osteoporosis is ubiquitous in Europe and ever-expanding in its implementation worldwide. DXA is known for its reported low radiation dose and precision in the determination of bone mineral density. However, the use of simple suspension criteria, as proposed in the new EC report RP-162, will identify units that are unfit for useful and safe diagnosis. Such suspension levels, however, are not a substitute for regular maintenance, quality control testing and optimisation of clinical outcomes.

  20. Comparison of bone density measurement techniques: DXA and Archimedes' principle.

    PubMed

    Keenan, M J; Hegsted, M; Jones, K L; Delany, J P; Kime, J C; Melancon, L E; Tulley, R T; Hong, K D

    1997-11-01

    The standard method for determination of density (g/cm3) of bones from small animals has been the application of Archimedes' principle. A recent development has been software for the determination of "density" (g/cm2) of small animal bones with dual-energy X-ray absorptiometry (DXA). We compared Archimedes' principle and DXA (Hologic QDR-2000) in the measurement of the densities of whole and hollowed femurs of 5- to 6-month-old retired female breeder rats. In an attempt to ensure detectable treatment differences, rats were used from a low-vitamin D Holtzman and a supplemental-vitamin D Sprague-Dawley colony. Whole femur densities were higher for supplemental-vitamin D colony rats than for low vitamin D rats using both techniques (Archimedes' principle, p < 0.002; DXA, p < 0.005), and the densities from the two techniques were highly correlated (r = 0.82, p < 0.0001). Actual density values were higher for Archimedes' principle than for DXA. Other variables such as femur ash weight and calcium content were also highly correlated to densities with both techniques. Hollowed femur density values were higher than whole femur values with Archimedes' principle but lower with DXA. Colony effects for hollowed femur densities were diminished with Archimedes' principle (p < 0.03) and eliminated with DXA (p < 0.53). Investigation of whole bones is more biologically relevant, and both techniques were effective in detecting differences between whole femurs from low-vitamin D and supplemental-vitamin D colony rats.

  1. Comparison of bone density measurement techniques: DXA and Archimedes' principle.

    PubMed

    Keenan, M J; Hegsted, M; Jones, K L; Delany, J P; Kime, J C; Melancon, L E; Tulley, R T; Hong, K D

    1997-11-01

    The standard method for determination of density (g/cm3) of bones from small animals has been the application of Archimedes' principle. A recent development has been software for the determination of "density" (g/cm2) of small animal bones with dual-energy X-ray absorptiometry (DXA). We compared Archimedes' principle and DXA (Hologic QDR-2000) in the measurement of the densities of whole and hollowed femurs of 5- to 6-month-old retired female breeder rats. In an attempt to ensure detectable treatment differences, rats were used from a low-vitamin D Holtzman and a supplemental-vitamin D Sprague-Dawley colony. Whole femur densities were higher for supplemental-vitamin D colony rats than for low vitamin D rats using both techniques (Archimedes' principle, p < 0.002; DXA, p < 0.005), and the densities from the two techniques were highly correlated (r = 0.82, p < 0.0001). Actual density values were higher for Archimedes' principle than for DXA. Other variables such as femur ash weight and calcium content were also highly correlated to densities with both techniques. Hollowed femur density values were higher than whole femur values with Archimedes' principle but lower with DXA. Colony effects for hollowed femur densities were diminished with Archimedes' principle (p < 0.03) and eliminated with DXA (p < 0.53). Investigation of whole bones is more biologically relevant, and both techniques were effective in detecting differences between whole femurs from low-vitamin D and supplemental-vitamin D colony rats. PMID:9383695

  2. Inaccuracies inherent in dual-energy X-ray absorptiometry in vivo bone mineral densitometry may flaw osteopenic/osteoporotic interpretations and mislead assessment of antiresorptive therapy effectiveness.

    PubMed

    Bolotin, H H

    2001-05-01

    New, anatomically realistic simulation studies based on a cadaveric lumbar vertebra and a broad range of soft tissue anthropometric representations have quantitatively delineated inaccuracies inherent in dual-energy X-ray absorptiometry (DXA) in vivo bone mineral density (BMD) methodology. It is found that systematic inaccuracies in DXA BMD measurements may readily exceed +/-20% at typical in vivo lumbar vertebral sites, especially for osteopenic/osteoporotic, postmenopausal, and elderly patients. These findings are quantitatively compared with extensive clinical evidence of strong, positive correlations between soft tissue anthropometrics and DXA in vivo BMD upon which prior significant bone biology interpretations and implications have been based. The agreement is found to be both qualitatively and quantitatively excellent. Moreover, recent extensive multicenter clinical studies have also exposed new facets of strong linkages between body mass/percent body fat/body mass index (BMI) and DXA-measured BMD that are particularly relevant to osteopenia/osteoporosis and remedial effectiveness of antiresorptive drug therapy. These seemingly disparate and unrelated diagnostic and prognostic aspects of clinically observed associations between soft tissue anthropometrics and measured vertebral BMD are, in this study, self-consistently shown to share the common origin of being manifestations of systematic inherent inaccuracies in DXA in vivo BMD methodology, without the need to invoke any underlying biologically causal mechanism(s). These inaccuracies arise principally from absorptiometric disparities between the intra- and extraosseous soft tissues within the DXA scan region of interest. The present evaluative comparisons are based exclusively on an incisive and diverse body of clinical data that appears difficult to dismiss or discount. Previous invocations of biologically causal mechanisms responsible for this broad range of observations linking body mass, percent body

  3. The long-term performance of DXA bone densitometers.

    PubMed

    Wells, J; Ryan, P J

    2000-07-01

    Long-term performance of a bone mass measuring device is an important criterion when considering the purchase of such equipment and has been regarded as an important feature of dual X-ray absorptiometry (DXA). The performance of a 6-year-old bone densitometer, the Lunar DPX alpha, which has undertaken 1500 scans annually over this period, was assessed. The short-term coefficient of variation calculated from 15 measurements with repositioning on a single day, using the Lunar aluminium phantom, was 0.242%. Long-term precision, also calculated by the coefficient of variation, was 0.548%. The manufacturer's quality control (QC) procedure was performed daily and allowed the machine to be used except on 15 occasions when bone density measurements could be acquired after rebooting. However, a 2.2% shift in phantom values occurred in July 1996 owing to a photomultiplier tube failure, but this did not produce a failure in the Lunar QC. The optical disc drive was replaced in July 1997. The machine failed to back up on six occasions over the last 2 years owing to software corruption and the acquired femur data were not saved on seven occasions owing to overloading of the memory buffer. In conclusion, expected hardware failure and minor software problems have occurred. We were concerned that the manufacturer's QC failed to detect a 2% shift in the phantom bone mineral density values and recommend regular measurements of the Lunar aluminum phantom in addition to the daily QC measurement of the tissue-equivalent block. We were nevertheless impressed by the long-term stability and reproducibility of the Lunar DPX alpha.

  4. On new opportunities for absorptiometry.

    PubMed

    Ferretti, J L; Schiessl, H; Frost, H M

    1998-01-01

    Mechanical loads cause bone strains; and muscle forces, not body weight, cause the largest strains. The strains help to control the effects of bone modeling and remodeling on bone strength and "mass." When strains exceed a threshold range, modeling increases bone strength and "mass." When strains stay below a smaller threshold range, remodeling begins removing bone next to marrow. As a result, increasing muscle strength increases bone strength and "mass," and decreasing muscle strength decreases bone strength and "mass." Estrogen apparently lowers the remodeling threshold, which reduces bone losses. Loss of estrogen raises that threshold to cause losses of bone next to marrow. Such facts help to explain: 1. Bone loss in aging adults. 2. An increase in bone "mass" in girls at menarche. 3. The loss of bone during menopause. 4. The greater bone "mass" in obese than in slender subjects, and in weightlifters than in marathon runners. 5. And the pathogenesis of physiologic osteopenias and true osteoporoses. Thus new standards are needed for the relationships between bone and muscle strengths, and as functions of sex, age, race, disease, endocrine status, nutrition, vitamin and mineral intakes, medications, puberty, and menopause. Obtaining those standards and studying such relationships provide many new opportunities for studies that involve dual energy X-ray absorptiometry (DXA) and peripheral quantitative computer tomography (pQCT) and, perhaps some day, ultrasound and magnetic resonance imaging (MRI) techniques. PMID:15304912

  5. In vivo precision of the GE Lunar iDXA densitometer for the measurement of total-body, lumbar spine, and femoral bone mineral density in adults.

    PubMed

    Hind, Karen; Oldroyd, Brian; Truscott, John G

    2010-01-01

    Knowledge of precision is integral to the monitoring of bone mineral density (BMD) changes using dual-energy X-ray absorptiometry (DXA). We evaluated the precision for bone measurements acquired using a GE Lunar iDXA (GE Healthcare, Waukesha, WI) in self-selected men and women, with mean age of 34.8 yr (standard deviation [SD]: 8.4; range: 20.1-50.5), heterogeneous in terms of body mass index (mean: 25.8 kg/m(2); SD: 5.1; range: 16.7-42.7 kg/m(2)). Two consecutive iDXA scans (with repositioning) of the total body, lumbar spine, and femur were conducted within 1h, for each subject. The coefficient of variation (CV), the root-mean-square (RMS) averages of SDs of repeated measurements, and the corresponding 95% least significant change were calculated. Linear regression analyses were also undertaken. We found a high level of precision for BMD measurements, particularly for scans of the total body, lumbar spine, and total hip (RMS: 0.007, 0.004, and 0.007 g/cm(2); CV: 0.63%, 0.41%, and 0.53%, respectively). Precision error for the femoral neck was higher but still represented good reproducibility (RMS: 0.014 g/cm(2); CV: 1.36%). There were associations between body size and total-body BMD and total-hip BMD SD precisions (r=0.534-0.806, p<0.05) in male subjects. Regression parameters showed good association between consecutive measurements for all body sites (r(2)=0.98-0.99). The Lunar iDXA provided excellent precision for BMD measurements of the total body, lumbar spine, femoral neck, and total hip.

  6. Prediction of fat-free body mass from bioelectrical impedance and anthropometry among 3-year-old children using DXA.

    PubMed

    Ejlerskov, Katrine T; Jensen, Signe M; Christensen, Line B; Ritz, Christian; Michaelsen, Kim F; Mølgaard, Christian

    2014-01-27

    For 3-year-old children suitable methods to estimate body composition are sparse. We aimed to develop predictive equations for estimating fat-free mass (FFM) from bioelectrical impedance (BIA) and anthropometry using dual-energy X-ray absorptiometry (DXA) as reference method using data from 99 healthy 3-year-old Danish children. Predictive equations were derived from two multiple linear regression models, a comprehensive model (height(2)/resistance (RI), six anthropometric measurements) and a simple model (RI, height, weight). Their uncertainty was quantified by means of 10-fold cross-validation approach. Prediction error of FFM was 3.0% for both equations (root mean square error: 360 and 356 g, respectively). The derived equations produced BIA-based prediction of FFM and FM near DXA scan results. We suggest that the predictive equations can be applied in similar population samples aged 2-4 years. The derived equations may prove useful for studies linking body composition to early risk factors and early onset of obesity.

  7. Prediction of fat-free body mass from bioelectrical impedance and anthropometry among 3-year-old children using DXA

    PubMed Central

    Ejlerskov, Katrine T.; Jensen, Signe M.; Christensen, Line B.; Ritz, Christian; Michaelsen, Kim F.; Mølgaard, Christian

    2014-01-01

    For 3-year-old children suitable methods to estimate body composition are sparse. We aimed to develop predictive equations for estimating fat-free mass (FFM) from bioelectrical impedance (BIA) and anthropometry using dual-energy X-ray absorptiometry (DXA) as reference method using data from 99 healthy 3-year-old Danish children. Predictive equations were derived from two multiple linear regression models, a comprehensive model (height2/resistance (RI), six anthropometric measurements) and a simple model (RI, height, weight). Their uncertainty was quantified by means of 10-fold cross-validation approach. Prediction error of FFM was 3.0% for both equations (root mean square error: 360 and 356 g, respectively). The derived equations produced BIA-based prediction of FFM and FM near DXA scan results. We suggest that the predictive equations can be applied in similar population samples aged 2–4 years. The derived equations may prove useful for studies linking body composition to early risk factors and early onset of obesity. PMID:24463487

  8. Dual-energy X-ray absorptiometry measured regional body composition least significant change: effect of region of interest and gender in athletes.

    PubMed

    Buehring, Bjoern; Krueger, Diane; Libber, Jessie; Heiderscheit, Bryan; Sanfilippo, Jennifer; Johnson, Brian; Haller, Irina; Binkley, Neil

    2014-01-01

    Dual-energy X-ray absorptiometry (DXA) is widely used to evaluate body composition in athletes. Knowledge of measurement precision is essential for monitoring body composition changes over time. This study begins characterizing DXA body composition precision in 60 (30 males and 30 females) Division 1 athletes focusing on gender, regional, and tissue type differences. Two total body scans with repositioning between were performed on the same day. Least significant change (LSC) for the root-mean-square deviation (LSCRMSD) and the percent coefficient of variation (LSC%CV) for total, lean, and fat mass was calculated for 6 regions of interest. The effect of gender, region, tissue type, and mass on the standard deviation (SD) and percent coefficient of variation (%CV) between the 2 scans was evaluated using repeated measures regression analysis. Statistically significant effects of gender, region, tissue type, and mass on SD and %CV were noted. To generalize, a nonlinear positive relationship between LSCRMSD and mass and a nonlinear negative relationship between LSC%CV and mass were observed. In conclusion, DXA body composition LSC varies among genders, regions, tissues, and mass. As such, when evaluating serial body composition in athletes, especially if assessing regional change, knowledge of precision in individuals of similar body size and gender to the population of interest is needed.

  9. An evaluation of the United Kingdom National Osteoporosis Society position statement on the use of peripheral dual-energy X-ray absorptiometry.

    PubMed

    Patel, Rajesh; Blake, Glen M; Fogelman, Ignac

    2004-06-01

    A recent position statement issued by the UK National Osteoporosis Society recommends a triage approach to the use of peripheral dual-energy X-ray absorptiometry (pDXA) devices. Patients with a forearm T-score greater than -1 or less than -2.5 are regarded as normal or osteoporotic, respectively, while those with a T-score between -1 and -2.5 are sent for further assessment with spine and hip DXA. We have evaluated the NOS pDXA algorithm by comparing it with the alternative strategies of relying on forearm BMD alone, or performing spine and hip DXA in every patient. The evaluation was carried out using a mathematical model, and the predictions were compared with in vivo data obtained in patients referred for investigation by their general practitioner. In the model the population distribution of spine, hip, and forearm BMD was described by a trivariant Gaussian function. Relative risks of fracture were taken from a meta-analysis. The three strategies were compared using receiver operating characteristic (ROC) curves in which the percentage of future fracture cases identified was plotted against the percentage of the whole population found to have osteoporosis. ROC curves plotted for the discrimination of hip, vertebral, and Colles fracture risk and the risk of a fracture at any skeletal site were similar for all three strategies, with the curves for the NOS pDXA algorithm nearly identical to those for spine and hip DXA. For the case of hip fracture, vertebral fracture, or a fracture at any site, forearm BMD was slightly inferior to the NOS algorithm, but the reverse was true for Colles fracture. The small difference between the ROC curves suggests that forearm BMD used alone can reproduce clinical decision-making with the NOS pDXA algorithm provided that a T-score threshold of T=-2.1 is used for the diagnosis of osteoporosis, instead of the conventional figure of T=-2.5. Results from the in vivo study were in good agreement with the predictions of the model

  10. Black hole artifacts-a new potential pitfall for DXA accuracy?

    PubMed

    Morgan, Sarah L; Lopez-Ben, Robert; Nunnally, Nancy; Burroughs, Leandria; Fineberg, Naomi; Tubbs, R Shane; Yester, Michael V

    2008-01-01

    Certain types of metallic objects apparently have high attenuation (a white image) on dual-energy X-ray absorptiometry (DXA) scan images, but instead show up as black (black hole artifacts). When small, these artifacts may easily be missed on visual inspection. We hypothesized that such "black hole" artifacts could have a significant effect on bone mineral density (BMD) results. Human use approval (Institutional Review Board [IRB]) was obtained to publish patient scans and an IRB waiver was obtained for nonhuman research. We placed individual surgical clips and cassettes of clips of tantalum, stainless steel and titanium, and a bullet over the third lumbar vertebra (L3) of a Hologic spine phantom. In addition, 4 or 8 individual tantalum or stainless steel clips and tantalum squares were placed over L3 of cadaveric spines (high-density spine L1-L4 BMD=1.049 g/cm2) and low-density spine BMD (L1-L4 BMD=0.669 g/cm2) with attached soft tissues. Stainless steel and titanium clips scanned as white objects with DXA. A bullet and tantalum clips scanned black (black holes). All clip types were visible on single-energy scans as white objects. Eight tantalum clips significantly lowered L3 BMD compared to 4 or 0 clips in the high-density spine. There were no significant differences in BMD L1-L4 between 0, 4, and 8 tantalum clips in the high-density spine. In the low-density spine, 8 tantalum clips over L3 had significantly lower BMD compared to 4 tantalum clips overlying L3 and 4 clips lateral to L3 and 4 clips over L3. All of these scenarios had lower L3 BMD than no tantalum clips overlying L3. The BMD of L1-L4 was lowest with 8 clips at L3, but was not significantly different than no clips overlying L3. Eight tantalum clips lateral to L3 was significantly higher than no clips over L3. Black hole artifacts can occur in DXA scans containing certain metals like tantalum surgical clips. Although these surgical clips could decrease BMD at a localized area, they do not

  11. Is bone mineral density measurement using dual-energy X-ray absorptiometry affected by gamma rays?

    PubMed

    Xie, Liang-Jun; Li, Jian-Fang; Zeng, Feng-Wei; Jiang, Hang; Cheng, Mu-Hua; Chen, Yi

    2013-01-01

    The objective of this study was to determine whether the gamma rays emitted from the radionuclide effect bone mineral density (BMD) measurement. Nine subjects (mean age: 56 ± 17.96 yr) scheduled for bone scanning underwent BMD measurement using dual-energy X-ray absorptiometry (DXA) (Hologic/Discovery A) before and 1, 2, and 4 h after injection of technetium-99m-methylene diphosphonate (99mTc-MDP). Ten subjects (mean age: 41 ± 15.47 yr) scheduled for therapy of differentiated thyroid carcinoma with iodine-131 underwent BMD measurement before and 2 h after therapeutic radionuclide administration. All patients were given whole body BMD measurement, including head, arm, ribs, lumbar spine, pelvis, and leg sites. Besides, patients who referred to radioiodine therapy were given total hip and femoral neck BMD measurement as well. No statistically significant changes in BMD values were detected after 99mTc-MDP and iodine-131 administration for all measurement sites (p > 0.05), and individual difference of BMD before and after radionuclide imaging or therapy was less than the least significant change in lumbar spine, total hip, and femoral neck. In conclusion, BMD measurements are not influenced by the gamma rays emitted from technetium-99m and iodine-131. DXA bone densitometry may be performed simultaneously with bone scanning and radioiodine therapy.

  12. Dual X-ray absorptiometry detects disease- and treatment-related alterations of bone density in prostate cancer patients.

    PubMed

    Smith, G L; Doherty, A P; Banks, L M; Dutton, J; Hanham, L W; Christmas, T J; Epstein, R J

    2000-01-01

    Metastatic bone disease is an important clinical problem which has proven difficult to study because of a lack of noninvasive investigative modalities. Here we show that dual-energy X-ray absorptiometry (DXA) scanning provides clinically useful information about the status of metastatic bone lesions in cancer patients undergoing palliative treatment. In the study group of 21 patients, a significant increase in metastatic bone mineral density (BMD) was confirmed in prostate (n = 14) relative to breast (n = 7) cancer patients. With respect to the prostate cancer cohort, further increases in lesional BMD were evident in all evaluable patients in whom biochemical progression occurred; conversely, lesional BMD declined in patients who had a partial response to therapy. BMD of uninvolved bone decreased with all types of androgen-deprivation therapy regardless of whether patients responded or relapsed. We conclude that BMD changes in both lesional and uninvolved bone are readily detectable in metastatic prostate cancer, and propose that DXA scanning represents a promising new approach to monitoring the natural history and therapeutic course of this disease.

  13. Cross-calibration of pencil-beam (DPX-NT) and fan-beam (QDR-4500C) dual-energy X-ray absorptiometry for sarcopenia.

    PubMed

    Ito, Kenyu; Tsushita, Kazuyo; Muramoto, Akiko; Kanzaki, Hiroki; Nohara, Takashi; Shimizu, Hitomi; Nakazawa, Tomoko; Harada, Atsushi

    2015-11-01

    Sarcopenia, defined as the loss of muscle mass accompanied by weakness, is an important factor leading to frailty and is a growing concern in the aging Japanese society. Muscle mass can be calculated by dual-energy X-ray absorptiometry (DXA), but results differ between devices produced by different manufactures. Thus, cross-calibration is needed to compare body composition results in multicenter trials or when scanners are replaced. The purpose of this study was to perform an in vivo calibration of total body scans between pencil-beam (DPX-NT, GE Healthcare) and fan-beam (QDR-4500C, Hologic Inc.) DXA units. A total 30 subjects (15 women, 15 men, mean age = 35 years, range 22-49 years) were recruited. The lumbar bone mineral density (BMD), femoral neck BMD, appendicular fat and lean body mass, and the appendicular skeletal muscle mass index (ASMI) were highly correlated (r = 0.979-0.993, r(2) = 0.889-0.977). The conversion formulas were as follows: lumbar BMD, Y = -0.08 + 1.16X (X = QDR-4500C, Y = DPX-NT), femoral neck BMD, Y = -0.015 + 1.11X, and ASMI Y = 0.92 + 0.90X. There is excellent comparability between the DPX-NT and the QDR-4500C DXA units. However, cross-calibration equations are required to assess muscle volume, fat, and ASMI in multicenter studies investigating sarcopenia.

  14. Body Composition in Premature Adrenarche by Structural MRI, 1H MRS and DXA

    PubMed Central

    Leibel, Natasha; Shen, Wei; Mao, Xiangling; Punyanitya, Mark; Gallagher, Dympna; Horlick, Mary; Shungu, Dikoma C.; Oberfield, Sharon E.

    2010-01-01

    Background Premature adrenarche (PA) is recognized to be a possible precursor of polycystic ovarian syndrome, type 2 diabetes mellitus and cardiovascular disease. Visceral adiposity and increased intramyocellular lipid (IMCL) are associated with insulin resistance and increased risk of cardiovascular disease. Aim To determine whether prepubertal girls with PA have altered visceral adiposity and/or increased muscle lipid content compared to prepubertal girls without PA using proton magnetic resonance imaging (MRI) and spectroscopy (1H MRS). Patients and Methods We performed total body dual energy X-ray absorptiometry (DXA) scans, MRI of the trunk, and MRS of the tibialis anterior muscle in the right calf on six girls with PA and eight prepubertal controls. Results Amount of visceral adipose tissue (VAT), abdominal subcutaneous adipose tissue (SAT), and VAT to SAT ratio did not differ significantly between the PA and control girls. Those with PA, however, had significantly greater IMCL than controls (p = 0.004). Conclusions This study adds further evidence that PA is not a benign condition, and future studies investigating early intervention with dietary and exercise counseling may help diminish potential risk for diabetes mellitus and/or cardiovascular disease. PMID:19554803

  15. Dual-energy X-ray absorptiometry in sheep: experiences with in vivo and ex vivo studies.

    PubMed

    Turner, A S; Mallinckrodt, C H; Alvis, M R; Bryant, H U

    1995-10-01

    As different large animal models of osteopenia and osteoporosis are explored, the use of DXA to rapidly, non-invasively and accurately estimate BMD will become widespread. We used DXA in live sheep and cadaveric material and the areas of trabecular bone that are most accessible on a simple, repeatable basis in the sheep were the lumbar vertebrae (L4-L6/L5-L7), the CAL and the DR. We performed dual-energy X-ray absorptiometry (DXA) using an Hologic QDR 1000-W bone densitometer to measure bone mineral density (BMD) at various regions of interest in anesthetized sheep and cadaveric specimens of sheep. In vivo measurements of L4-L6/L5-L7, the calcaneus (CAL) and distal radius (DR) in 48 intact 3 to 5-year-old ewes (same breed) were performed. Correlations between the different bones were investigated. In an in vivo precision study, BMD of L3-L6/L7, CAL and DR was determined with one animal repositioned between 10 scans of each bone. In another study, ex-vivo BMD measurements of the proximal and distal femur, proximal tibia, and proximal humerus were performed on isolated bones of 45 ewes of similar age. Excised vertebrae were scanned on the Hologic QDR 1000-W and on a Lunar DPX (at another site) and the data were compared. Correlations of BMD between individual vertebrae in anesthetized sheep were excellent (r = 0.944- 0.843; P < 0.0001). Correlation between BMD of individual vertebrae and CAL was good (r = 0.677-0.630), while correlation between BMD of individual vertebrae and DR was also good (r = 0.551-0.507; P < .0001).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8579941

  16. Osteoporosis pharmacotherapy following bone densitometry: importance of patient beliefs and understanding of DXA results

    PubMed Central

    Cadarette, S. M.; Eskildsen, P.; Abrahamsen, B.

    2016-01-01

    Summary Persistence with osteoporosis therapy remains low and identification of factors associated with better persistence is essential in preventing osteoporosis and fractures. In this study, patient understanding of dual energy X-ray absorptiometry (DXA) results and beliefs in effects of treatment were associated with treatment initiation and persistence. Introduction The purpose of this study is to examine patient understanding of their DXA results and evaluate factors associated with initiation of and persistence with prescribed medication in first-time users of anti-osteoporotic agents. Self-reported DXA results reflect patient understanding of diagnosis and may influence acceptance of osteoporosis therapy. To improve patient understanding of DXA results, we provided written information to patients and their referring general practitioner (GP), and evaluated factors associated with osteoporosis treatment initiation and 1-year persistence. Methods Information on diagnosis was mailed to 1,000 consecutive patients and their GPs after DXA testing. One year after, a questionnaire was mailed to all patients to evaluate self-report of DXA results, drug initiation and 1-year persistence. Quadratic weighted kappa was used to estimate agreement between self-report and actual DXA results. Multivariable logistic regression was used to evaluate predictors of understanding of diagnosis, and correlates of treatment initiation and persistence. Results A total of 717 patients responded (72%). Overall, only 4% were unaware of DXA results. Agreement between self-reported and actual DXA results was very good (κ=0.83); younger age and glucocorticoid use were associated with better understanding. Correctly reported DXA results was associated with treatment initiation (OR 4.3, 95% CI 1.2–15.1, p=0.02), and greater beliefs in drug treatment benefits were associated with treatment initiation (OR 1.4, 95%CI 1.1–1.9, p=0.006) and persistence with therapy (OR 1.8, 95% CI 1.2–2

  17. Hip Fractures Risk in Older Men and Women Associated With DXA-Derived Measures of Thigh Subcutaneous Fat Thickness, Cross-Sectional Muscle Area, and Muscle Density.

    PubMed

    Malkov, Serghei; Cawthon, Peggy M; Peters, Kathy Wilt; Cauley, Jane A; Murphy, Rachel A; Visser, Marjolein; Wilson, Joseph P; Harris, Tamara; Satterfield, Suzanne; Cummings, Steve; Shepherd, John A

    2015-08-01

    Mid-thigh cross-sectional muscle area (CSA), muscle attenuation, and greater trochanter soft tissue thickness have been shown to be independent risk factors of hip fracture. Our aim was to determine whether muscle and adipose tissue measures derived from dual-energy X-ray absorptiometry (DXA) scans would have a similar risk association as those measured using other imaging methods. Using a case-cohort study design, we identified 169 incident hip fracture cases over an average of 13.5 years among participants from the Health ABC Study, a prospective study of 3075 individuals initially aged 70 to 79 years. We modeled the thigh 3D geometry and compared DXA and computed tomography (CT) measures. DXA-derived thigh CSA, muscle attenuation, and subcutaneous fat thickness were found to be highly correlated to their CT counterparts (Pearson's r = 0.82, 0.45, and 0.91, respectively; p < 0.05). The fracture risk of men and women were calculated separately. We found that decreased subcutaneous fat, CT thigh muscle attenuation, and appendicular lean mass by height squared (ALM/Ht(2)) were associated with fracture risk in men; hazard ratios (HR) = 1.44 (1.02, 2.02), 1.40 (1.05, 1.85), and 0.58 (0.36, 0.91), respectively, after adjusting for age, race, clinical site, body mass index (BMI), chronic disease, hip bone mineral density (BMD), self-reported health, alcohol use, smoking status, education, physical activity, and cognitive function. In a similar model for women, only decreases in subcutaneous fat and DXA CSA were associated with hip fracture risk; HR = 1.39 (1.07, 1.82) and 0.78 (0.62, 0.97), respectively. Men with a high ALM/Ht(2) and low subcutaneous fat thickness had greater than 8 times higher risk for hip fracture compared with those with low ALM/Ht(2) and high subcutaneous fat. In women, ALM/Ht(2) did not improve the model when subcutaneous fat was included. We conclude that the DXA-derived subcutaneous fat thickness is a strong marker for hip fracture

  18. Total-body calcium estimated by delayed gamma neutron activation analysis and dual-energy X-ray absorptiometry.

    PubMed

    Aloia, J F; Ma, R; Vaswani, A; Feuerman, M

    1999-01-01

    Total body calcium (TBCa) in 270 black and white women age 21-79 years was measured concurrently by delayed gamma neutron activation analysis (DGNA) and dual-energy X-ray absorptiometry (DXA). The mean value for TBCa calculated from DXA was 933 g compared with 730 g for DGNA. By regression, TBCa(DXA(g)) = 1.35 x TBCa(DGNA(g)) -54 (r = 0. 90, r(2) = 81.4%, SEE = 66.9 g). This remarkable difference of 203 g suggests that one or both these methods is not accurate. Adjustment of the regression of DXA versus DGNA for body mass index or trunk thickness explained 8.5-10% of the variability between methods. The unadjusted slope for the DXA values regressed against the DGNA values was 1.35, indicating significant discordance between the methods. There is greater agreement between the two DGNA facilities (Brookhaven National Laboratory and Baylor College of Medicine) and between the various DXA instruments. Either DGNA underestimates TBCa or DXA overestimates total-body bone mineral content. Resolution of these disparate results may possibly be achieved by concurrent measurement of whole human cadavers of different sizes with chemical determination of the calcium content of the ash. In the interim, cross-calibration equations between DGNA and standardized values for DXA for total-body bone mineral content may be used, which will permit reporting of consistent values for TBCa from the two technologies. PMID:10663353

  19. Dual-Energy X-Ray Absorptiometry Prediction of Adipose Tissue Depots in Children and Adolescents

    PubMed Central

    Bauer, Jacqueline; Thornton, John; Heymsfield, Steven; Kelly, Kim; Ramirez, Alexander; Gidwani, Sonia; Gallagher, Dympna

    2013-01-01

    Background The measurement of adipose tissue depots in-vivo requires expensive imaging methods not accessible to most clinicians and researchers. The study aim was to derive mathematical models to predict total adipose tissue (TAT) and sub-depots from total body fat derived from a dual energy x-ray absorptiometry (DXA) scan. Methods Models were developed to predict magnetic resonance imaging derived TAT and sub-depots subcutaneous (SAT), visceral (VAT), and intermuscular (IMAT) from DXA total body fat using cross-sectional data (T0) and validated results using 1 (T1) and 2 (T2) year follow-up data. Subjects were 176 multi-ethnic healthy children ages 5 to 17 years at T0. 22 were measured at T1 and T2. TAT was compared to fat. Results At T0, TAT was greater than fat (12.5 ± 8.4 vs.12.0 ± 9.4 kg; p< 0.0001), with a quadratic relationship between TAT and fat which varied by sex. Predicted mean TAT’s were not different from measured TAT’s: T1: (9.84±4.45 kg vs. 9.50±4.37 kg; p=0.11) T2: (12.94±6.75 kg vs. 12.89±7.09 kg; p=0.76). The quadratic relationship was not influenced by race or age. Conclusions In general, the prediction equations for TAT and sub-depots were consistent with the measured values using T1 and T2 data. PMID:22821057

  20. Validation and application of dual-energy X-ray absorptiometry to measure bone mineral density in rabbit vertebrae.

    PubMed

    Norris, S A; Pettifor, J M; Gray, D A; Biscardi, A; Buffenstein, R

    2000-01-01

    The rabbit could be a superior animal model to use in bone physiology studies, for the rabbit does attain true skeletal maturity. However, there are neither normative bone mineral density (BMD) data on the rabbit nor are there any validation studies on the use of dual-energy X-ray absorptiometry (DXA) to measure spinal BMD in the rabbit. Therefore, our aim was twofold: first, to investigate whether DXA could be used precisely and accurately to determine the bone mineral content (BMC). bone area (BA). and BMD of the rabbit lumbar spine: Second. to evaluate the new generation fan-beam DXA (Hologic QDR-4500) with small animal software by comparing two DXA methodologies QDR-1000 and QDR-4500 with each other, as well as against volumetric bone density (VBMD) derived from Archimedes principle. As expected. there was a magnification error in the QDR-4500 (BMC, BA. and BMD increased by 52%. 38%. and 10%, respectively, when the vertebrae were positioned flat against the scanning table). With the magnification error kept constant (vertebrae positioned 10 cm above the scanning table to match the height in vivo). there were no differences among the mean BMC. BA. and BMD of the rabbit vertebrae (Ll-L7) in vivo and in vitro using the QDR-4500 (p > 0.05). BMC, BA, and BMD differed between QDR-1000 and QDR-4500 in vitro because of a magnification error when the vertebrae were flat on the table (p <0.0001). and, consequently. the machines did not correlate with one another (p > 0.05). However, the BMC, BA, and BMD of the two DXAs did significantly correlate with each other in vivo and in vitro when the magnification error was compensated for (r = 0.44 and 0.52. i2 = 0.45 and 0.63. and 12 = 0.41 and 0.60. respectively. p < 0.05-0.008). The BMC and BMD (in vivo and in vitro) of the rabbit vertebrae measured by QDR-4500 was significantly correlated with VMBD, ash weight, and mineral content (,2 = 0.67-0.90,j <0.01-0.0001). Therefore, the QDR-4500 can be used to yield precise and

  1. Assessment of trabecular bone quality in human cadaver calcaneus using scanning confocal ultrasound and dual x-ray absorptiometry (DEXA) measurements

    NASA Astrophysics Data System (ADS)

    Qin, Yixian; Xia, Yi; Lin, Wei; Rubin, Clinton; Gruber, Barry

    2004-10-01

    Microgravity and aging induced bone loss is a critical skeleton complication, occurring particularly in the weight-supporting skeleton, which leads to osteoporosis and fracture. Advents in quantitative ultrasound (QUS) provide a unique method for evaluating bone strength and density. Using a newly developed scanning confocal acoustic diagnostic (SCAD) system, QUS assessment for bone quality in the real body region was evaluated. A total of 19 human cadaver calcanei, age 66 to 97 years old, were tested by both SCAD and nonscan mode. The scanning region covered an approximate 40×40 mm2 with 0.5 mm resolution. Broadband ultrasound attenuation (BUA, dB/MHz), energy attenuation (ATT, dB), and ultrasound velocity (UV, m/s) were measured. The QUS properties were then correlated to the bone mineral density (BMD) measured by DEXA. Correlations between BMD and QUS parameters were significantly improved by using SCAD as compared to nonscan mode, yielding correlations between BMD and SCAD QUS parameters as R=0.82 (BUA), and R=0.86 (est. BMD). It is suggested that SCAD is feasible for in vivo bone quality mapping. It can be potentially used for monitoring instant changes of bone strength and density. [Work supported by the National Space Biomedical Research Institute (TD00207), and New York Center for Biotechnology.

  2. Determination of thigh volume in youth with anthropometry and DXA: agreement between estimates.

    PubMed

    Coelho-E-Silva, Manuel J; Malina, Robert M; Simões, Filipe; Valente-Dos-Santos, João; Martins, Raul A; Vaz Ronque, Enio R; Petroski, Edio L; Minderico, Claudia; Silva, Analiza M; Baptista, Fátima; Sardinha, Luís B

    2013-01-01

    This study examined the agreement between estimates of thigh volume (TV) with anthropometry and dual-energy x-ray absorptiometry (DXA) in healthy school children. Participants (n=168, 83 boys and 85 girls) were school children 10.0-13.9 years of age. In addition to body mass, height and sitting height, anthropometric dimensions included those needed to estimate TV using the equation of Jones & Pearson. Total TV was also estimated with DXA. Agreement between protocols was examined using linear least products regression (Deming regressions). Stepwise regression of log-transformed variables identified variables that best predicted TV estimated by DXA. The regression models were then internally validated using the predicted residual sum of squares method. Correlation between estimates of TV was 0.846 (95%CI: 0.796-0.884, Sy·x=0.152 L). It was possible to obtain an anthropometry-based model to improve the prediction of TVs in youth. The total volume by DXA was best predicted by adding body mass and sum of skinfolds to volume estimated with the equation of Jones & Pearson (R=0.972; 95%CI: 0.962-0.979; R (2)=0.945).

  3. Dual-energy X-ray absorptiometry derived structural geometry for stress fracture prediction in male U.S. Marine Corps recruits.

    PubMed

    Beck, T J; Ruff, C B; Mourtada, F A; Shaffer, R A; Maxwell-Williams, K; Kao, G L; Sartoris, D J; Brodine, S

    1996-05-01

    A total of 626 U.S. male Marine Corps recruits underwent anthropometric measurements and dual-energy X-ray absorptiometry (DXA) scans of the femoral midshaft and the distal third of the tibia prior to a 12 week physical training program. Conventionally obtained frontal plane DXA scan data were used to measure the bone mineral density (BMD) as well as to derive the cross-sectional area, moment of inertia, section modulus, and bone width in the femur, tibia, and fibula. During training, 23 recruits (3.7%) presented with a total of 27 radiologically confirmed stress fractures in various locations in the lower extremity. After excluding 16 cases of shin splints, periostitis, and other stress reactions that did not meet fracture definition criteria, we compared anthropometric and bone structural geometry measurements between fracture cases and the remaining 587 normals. There was no significant difference in age (p = 0.8), femur length (p = 0.2), pelvic width (p = 0.08), and knee width at the femoral condyles (p = 0.06), but fracture cases were shorter (p = 0.01), lighter (p = 0.0006), and smaller in most anthropometric girth dimensions (p < 0.04). Fracture case bone cross-sectional areas (p < 0.001), moments of inertia (p < 0.001), section moduli (p < 0.001), and widths (p < 0.001) as well as BMD (p < 0.03) were significantly smaller in the tibia and femur. After correcting for body weight differences, the tibia cross-sectional area (p = 0.03), section modulus (p = 0.05), and width (p = 0.03) remained significantly smaller in fracture subjects. We conclude that both small body weight and small diaphyseal dimensions relative to body weight are factors predisposing to the development of stress fractures in this population. These results suggest that bone structural geometry measurements derived from DXA data may provide a simple noninvasive methodology for assessing the risk of stress fracture.

  4. Ultrasound-Derived Abdominal Muscle Thickness Better Detects Metabolic Syndrome Risk in Obese Patients than Skeletal Muscle Index Measured by Dual-Energy X-Ray Absorptiometry.

    PubMed

    Ido, Ayumi; Nakayama, Yuki; Ishii, Kojiro; Iemitsu, Motoyuki; Sato, Koji; Fujimoto, Masahiro; Kurihara, Toshiyuki; Hamaoka, Takafumi; Satoh-Asahara, Noriko; Sanada, Kiyoshi

    2015-01-01

    Sarcopenia has never been diagnosed based on site-specific muscle loss, and little is known about the relationship between site-specific muscle loss and metabolic syndrome (MetS) risk factors. To this end, this cross-sectional study aimed to investigate the relationship between site-specific muscle size and MetS risk factors. Subjects were 38 obese men and women aged 40-82 years. Total body fat and lean body mass were assessed by whole-body dual-energy X-ray absorptiometry (DXA) scan. Muscle thickness (MTH) was measured using B-mode ultrasound scanning in six body regions. Subjects were classified into general obesity (GO) and sarcopenic obesity (SO) groups using the threshold values of one standard deviation below the sex-specific means of either MTH or skeletal muscle index (SMI) measured by DXA. MetS risk score was acquired by standardizing and summing the following continuously distributed variables: visceral fat area, mean blood pressure, HbA1c, and serum triglyceride / high density lipoprotein cholesterol, to obtain the Z-score. Multiple regression analysis revealed that the MetS risk score was independently associated with abdominal MTH in all subjects, but not with MTH in other muscle regions, including the thigh. Although HbA1c and the number of MetS risk factors in the SO group were significantly higher than those in the GO group, there were no significant differences between GO and SO groups as defined by SMI. Ultrasound-derived abdominal MTH would allow a better assessment of sarcopenia in obese patients and can be used as an alternative to the conventionally-used SMI measured by DXA. PMID:26700167

  5. Comparison of body composition techniques before and after a 161-km ultramarathon using DXA, BIS and BIA.

    PubMed

    Hew-Butler, T; Holexa, B T; Fogard, K; Stuempfle, K J; Hoffman, M D

    2015-02-01

    The low cost, ease of application and portability of bioelectrical impedance analysis (BIA) and spectroscopy (BIS) devices make them attractive tools for measuring acute changes in body composition before and after exercise, despite potential limitations from active compartmental fluid shifts. The primary study aim was to evaluate use of dual energy x-ray absorptiometry (DXA) against BIA and BIS in measurements of percent body fat (%BF) and percent total body water (%TBW) before and after prolonged endurance exercise. 10 runners were measured pre-race and at race finish. Significant linear relationships were noted pre-race between DXA vs. BIS for %BF (r(2)=0.76; p<0.01) and %TBW (r(2)=0.74; p<0.01). Significant correlations were noted at race finish between DXA vs. BIS for %BF (r(2)=0.64; p<0.01) and %TBW (r(2)=0.66; p<0.05), but only when one outlier was removed. Limits of agreement (LOA) between DXA vs. BIS were wide for both %BF (mean difference of -3.6, LOA between 5.4 and -12.6) and %TBW (mean difference 2.4, LOA between 0.4 and -4.6). LOA was closer between the DXA vs. BIA with DXA measuring slightly higher than BIA for %BF (mean difference of 0.5, LOA between 2.1 and -3.1) and slightly lower than BIA for %TBW (mean difference 0.3, LOA between 3.3 and -2.7). Linear correlations between DXA vs. BIA were not statistically significant for %BF or %TBW before or after the race. DXA measurement of acute changes in %BF and %TBW are not congruent with BIA or BIS measurements. These 3 techniques should not be utilized interchangeably after prolonged endurance running. PMID:25285467

  6. Dual X-ray absorptiometry

    NASA Astrophysics Data System (ADS)

    Altman, Albert; Aaron, Ronald

    2012-07-01

    Dual X-ray absorptiometry is widely used in analyzing body composition and imaging. Both the method and its limitations are related to the Compton and photoelectric contributions to the X-ray attenuation coefficients of materials.

  7. Utilization of DXA Bone Mineral Densitometry in Ontario

    PubMed Central

    2006-01-01

    Executive Summary Issue Systematic reviews and analyses of administrative data were performed to determine the appropriate use of bone mineral density (BMD) assessments using dual energy x-ray absorptiometry (DXA), and the associated trends in wrist and hip fractures in Ontario. Background Dual Energy X-ray Absorptiometry Bone Mineral Density Assessment Dual energy x-ray absorptiometry bone densitometers measure bone density based on differential absorption of 2 x-ray beams by bone and soft tissues. It is the gold standard for detecting and diagnosing osteoporosis, a systemic disease characterized by low bone density and altered bone structure, resulting in low bone strength and increased risk of fractures. The test is fast (approximately 10 minutes) and accurate (exceeds 90% at the hip), with low radiation (1/3 to 1/5 of that from a chest x-ray). DXA densitometers are licensed as Class 3 medical devices in Canada. The World Health Organization has established criteria for osteoporosis and osteopenia based on DXA BMD measurements: osteoporosis is defined as a BMD that is >2.5 standard deviations below the mean BMD for normal young adults (i.e. T-score <–2.5), while osteopenia is defined as BMD that is more than 1 standard deviation but less than 2.5 standard deviation below the mean for normal young adults (i.e. T-score< –1 & ≥–2.5). DXA densitometry is presently an insured health service in Ontario. Clinical Need   Burden of Disease The Canadian Multicenter Osteoporosis Study (CaMos) found that 16% of Canadian women and 6.6% of Canadian men have osteoporosis based on the WHO criteria, with prevalence increasing with age. Osteopenia was found in 49.6% of Canadian women and 39% of Canadian men. In Ontario, it is estimated that nearly 530,000 Ontarians have some degrees of osteoporosis. Osteoporosis-related fragility fractures occur most often in the wrist, femur and pelvis. These fractures, particularly those in the hip, are associated with increased

  8. Peripheral dual-energy X-ray absorptiometry in the management of osteoporosis: the 2007 ISCD Official Positions.

    PubMed

    Hans, Didier B; Shepherd, John A; Schwartz, Elliott N; Reid, David M; Blake, Glen M; Fordham, John N; Fuerst, Thomas; Hadji, Peyman; Itabashi, Akira; Krieg, Marc-Antoine; Lewiecki, E Michael

    2008-01-01

    Peripheral assessment of bone density using photon absorptiometry techniques has been available for over 40 yr. The initial use of radio-isotopes as the photon source has been replaced by the use of X-ray technology. A wide variety of models of single- or dual-energy X-ray measurement tools have been made available for purchase, although not all are still commercially available. The Official Positions of the International Society for Clinical Densitometry (ISCD) have been developed following a systematic review of the literature by an ISCD task force and a subsequent Position Development Conference. These cover the technological diversity among peripheral dual-energy X-ray absorptiometry (pDXA) devices; define whether pDXA can be used for fracture risk assessment and/or to diagnose osteoporosis; examine whether pDXA can be used to initiate treatment and/or monitor treatment; provide recommendations for pDXA reporting; and review quality assurance and quality control necessary for effective use of pDXA.

  9. Fundamental Movement Skill Proficiency and Body Composition Measured by Dual Energy X-Ray Absorptiometry in Eight-Year-Old Children

    ERIC Educational Resources Information Center

    Slotte, Sari; Sääkslahti, Arja; Metsämuuronen, Jari; Rintala, Pauli

    2015-01-01

    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…

  10. Validation of fan beam dual energy x ray absorptiometry for body composition assessment in adults aged 18–45 years

    PubMed Central

    Norcross, J; Van Loan, M D

    2004-01-01

    Background: Pencil beam dual energy x ray absorptiometry (DXA) has been shown to provide valid estimates of body fat (%BF), but DXA fan beam technology has not been adequately tested to determine its validity. Objective: To compare %BF estimated from fan beam DXA with %BF determined using two and three compartment (2C, 3C) models. Methods: Men (n = 25) and women (n = 31), aged 18–41 years, participated in the study. Body density, from hydrostatic weighing, was used in the 2C estimate of %BF; DXA was used to determine bone mineral content (BMC) for the 3C estimate of %BF calculated using body density and BMC (3CBMC). DXA was also used to determine %BF. Analysis of variance was used to test for significant differences in %BF between sexes and among methods. Results: Women were significantly shorter, weighed less, had less fat free mass, and a higher %BF than men. No significant differences were found among methods (2C, 3CBMC, DXA) for determination of %BF in either sex. Although not significant, Bland-Altman plots showed that DXA gave higher values for %BF than the 2C and 3CBMC methods. Conclusion: DXA determination of %BF was not different from that of the 2C and 3CBMC models in this group of young adults. However, to validate fan beam DXA fully as a method for body composition assessment in a wide range of individuals and populations, comparisons are needed that use a 4C model with a measure of total body water and BMC. PMID:15273189

  11. A DXA Whole Body Composition Cross-Calibration Experience: Evaluation With Humans, Spine, and Whole Body Phantoms.

    PubMed

    Krueger, Diane; Libber, Jessie; Sanfilippo, Jennifer; Yu, Hui Jing; Horvath, Blaine; Miller, Colin G; Binkley, Neil

    2016-01-01

    New densitometer installation requires cross-calibration for accurate longitudinal assessment. When replacing a unit with the same model, the International Society for Clinical Densitometry recommends cross-calibrating by scanning phantoms 10 times on each instrument and states that spine bone mineral density (BMD) should be within 1%, whereas total body lean, fat, and %fat mass should be within 2% of the prior instrument. However, there is limited validation that these recommendations provide adequate total body cross-calibration. Here, we report a total body cross-calibration experience with phantoms and humans. Cross-calibration between an existing and new Lunar iDXA was performed using 3 encapsulated spine phantoms (GE [GE Lunar, Madison, WI], BioClinica [BioClinica Inc, Princeton, NJ], and Hologic [Hologic Inc, Bedford, MA]), 1 total body composition phantom (BioClinica), and 30 human volunteers. Thirty scans of each phantom and a total body scan of human volunteers were obtained on each instrument. All spine phantom BMD means were similar (within 1%; <-0.010 g/cm2 bias) between the existing and new dual-energy X-ray absorptiometry unit. The BioClinica body composition phantom (BBCP) BMD and bone mineral content (BMC) values were within 2% with biases of 0.005 g/cm2 and -3.4 g. However, lean and fat mass and %fat differed by 4.6%-7.7% with biases of +463 g, -496 g, and -2.8%, respectively. In vivo comparison supported BBCP data; BMD and BMC were within ∼2%, but lean and fat mass and %fat differed from 1.6% to 4.9% with biases of +833 g, -860 g, and -1.1%. As all body composition comparisons exceeded the recommended 2%, the new densitometer was recalibrated. After recalibration, in vivo bias was lower (<0.05%) for lean and fat; -23 and -5 g, respectively. Similarly, BBCP lean and fat agreement improved. In conclusion, the BBCP behaves similarly, but not identical, to human in vivo measurements for densitometer cross-calibration. Spine phantoms, despite good

  12. Bone loss after bariatric surgery: discordant results between DXA and QCT bone density

    PubMed Central

    Yu, Elaine W.; Bouxsein, Mary; Roy, Adam E.; Baldwin, Chantel; Cange, Abby; Neer, Robert M; Kaplan, Lee M.; Finkelstein, Joel S.

    2013-01-01

    Several studies, using dual-energy x-ray absorptiometry (DXA), have reported substantial bone loss after bariatric surgery. However, profound weight loss may cause artifactual changes in DXA areal bone mineral density (aBMD) results. Assessment of volumetric bone mineral density (vBMD) by quantitative computed tomography (QCT) may be less susceptible to such artifacts. We assessed changes in BMD of the lumbar spine and proximal femur prospectively for 1 year using DXA and QCT in 30 morbidly obese adults undergoing Roux-en-Y gastric bypass surgery and 20 obese non-surgical controls. At one year, subjects who underwent gastric bypass surgery lost 37 ± 2 kg compared with 3 ± 2 kg lost in the non-surgical controls (p<0.0001). Spine BMD declined more in the surgical group than in the non-surgical group whether assessed by DXA (−3.3 vs. −1.1%, p=0.034) or by QCT (−3.4 vs. 0.2%, p=0.010). Total hip and femoral neck aBMD declined significantly in the surgical group when assessed by DXA (−8.9 vs. −1.1%, p<0.0001 for the total hip and −6.1 vs. −2.0%, p=0.002 for the femoral neck), but no changes in hip vBMD were noted using QCT. Within the surgical group, serum P1NP and CTX levels increased by 82 ± 10% and by 220 ± 22%, respectively, by 6 months and remained elevated over 12 months (p<0.0001 for all). Serum calcium, vitamin D, and PTH levels remained stable in both groups. We conclude that moderate vertebral bone loss occurs in the first year after gastric bypass surgery. However, striking declines in DXA aBMD at the proximal femur were not confirmed with QCT vBMD measurements. These discordant results suggest that artifacts induced by large changes in body weight after bariatric surgery affect DXA and/or QCT measurements of bone, particularly at the hip. PMID:23929784

  13. Chemical versus dual energy x-ray absorptiometry for detecting age-associated body compositional changes in male rats☆

    PubMed Central

    Feely, Rebecca. S.; Larkin, Lisa M.; Halter, Jeffrey B.; Dengel, Donald R.

    2009-01-01

    Aging is associated with increases in body mass and fat mass (FM), whereas fat-free mass (FFM) either decreases or remains unchanged. The purpose of this study was to determine whether dual-energy X-ray absorptiometry (DXA) accurately detects age-associated changes in male Fischer 344 × Brown–Norway rats ages 8, 18, and 28 months. Eviscerated animal carcasses were first examined via the Lunar DPX-IQ DXA (small animal software version 1.0; HiRes (0.6 × 1.2 mm) medium mode). Eviscerated carcasses were then weighed, autoclaved, homogenized, and fat isolated from aliquots of homogenate via methanol/chloroform extraction. In both chemical (CHEM) and DXA analysis, carcass mass (CM), FM, and % fat were significantly higher (P < 0.0001) in the 18 and 28 versus 8-month-old rats. CHEM showed greater FFM in the 18 versus 8 months-old rats but not the 28 months-old animals. DXA was unable to detect the age-associated changes in FFM. Regression analysis showed a strong correlation between CHEM and DXA methods for CM (r = 0.98, P < 0.0001) and FM (r = 0.97, P < 0.0001), but less strong for FFM (r = 0.59, P = 0.0002). In conclusion, compared to CHEM, DXA consistently overestimated CM and FM across the age groups by 9% and 77%, respectively, and underestimated FFM by 5%. PMID:10832061

  14. Accuracy of DXA in estimating body composition changes in elite athletes using a four compartment model as the reference method

    PubMed Central

    2010-01-01

    Background Dual-energy x-ray absorptiometry (DXA) provides an affordable and practical assessment of multiple whole body and regional body composition. However, little information is available on the assessment of changes in body composition in top-level athletes using DXA. The present study aimed to assess the accuracy of DXA in tracking body composition changes (relative fat mass [%FM], absolute fat mass [FM], and fat-free mass [FFM]) of elite male judo athletes from a period of weight stability to prior to a competition, compared to a four compartment model (4C model), as the criterion method. Methods A total of 27 elite male judo athletes (age, 22.2 ± 2.8 yrs) athletes were evaluated. Measures of body volume by air displacement plethysmography, bone mineral content assessed by DXA, and total-body water assessed by deuterium dilution were used in a 4C model. Statistical analyses included examination of the coefficient of determinant (r2), standard error of estimation (SEE), slope, intercept, and agreement between models. Results At a group level analysis, changes in %FM, FM, and FFM estimates by DXA were not significantly different from those by the 4C model. Though the regression between DXA and the 4C model did not differ from the line of identity DXA %FM, FM, and FFM changes only explained 29%, 36%, and 38% of the 4C reference values, respectively. Individual results showed that the 95% limits of agreement were -3.7 to 5.3 for %FM, -2.6 to 3.7 for FM, and -3.7 to 2.7 for FFM. The relation between the difference and the mean of the methods indicated a significant trend for %FM and FM changes with DXA overestimating at the lower ends and underestimating at the upper ends of FM changes. Conclusions Our data indicate that both at group and individual levels DXA did not present an expected accuracy in tracking changes in adiposity in elite male judo athletes. PMID:20307312

  15. Comparison of the Bod Pod and dual energy x-ray absorptiometry in men.

    PubMed

    Ball, Stephen D; Altena, Thomas S

    2004-06-01

    The majority of studies investigating the accuracy of the Bod Pod have compared it to hydrostatic weighing (HW), the long held, and perhaps outdated 'gold standard' method of body composition analysis. Much less research has compared the Bod Pod to dual energy x-ray absorptiometry (DXA), a technique that is becoming popular as an alternative reference method. The purpose of this study was to compare per cent fat estimates by the Bod Pod to those of DXA in a large number of men. Participants were 160 men (32 +/- 11 years). Per cent body fat was estimated to be 19.4 +/- 6.8 and 21.6 +/- 8.4 for DXA and the Bod Pod, respectively. Although the two methods were highly correlated (0.94), the mean difference of 2.2% was significant (p < 0.01). The amount of difference increased as body fatness increased (p < 0.0001). The results of this study indicate that a difference between methods existed for our sample of men. It is uncertain exactly where the difference lies. Practitioners should be aware that even with the use of technologically sophisticated methods (i.e., Bod Pod, DXA), differences between methods exist and the determination of body composition is at best, an estimation.

  16. Body Segment Inertial Parameters of elite swimmers Using DXA and indirect Methods

    PubMed Central

    Rossi, Marcel; LYTTLE, Andrew; EL-SALLAM, Amar; BENJANUVATRA, Nat; BLANKSBY, Brian

    2013-01-01

    As accurate body segment inertial parameters (BSIPs) are difficult to obtain in motion analysis, this study computed individual BSIPs from DXA scan images. Therefore, by co-registering areal density data with DXA grayscale image, the relationship between pixel color gradient and the mass within the pixel area could be established. Thus, one can calculate BSIPs, including segment mass, center of mass (COM) and moment of inertia about the sagittal axis (Ixx). This technique calculated whole body mass very accurately (%RMSE of < 1.5%) relatively to results of the generic DXA scanner software. The BSIPs of elite male and female swimmers, and young adult Caucasian males (n = 28), were computed using this DXA method and 5 other common indirect estimation methods. A 3D surface scan of each subject enabled mapping of key anthropometric variables required for the 5 indirect estimation methods. Mass, COM and Ixx were calculated for seven body segments (head, trunk, head + trunk, upper arm, forearm, thigh and shank). Between-group comparisons of BSIPs revealed that elite female swimmers had the lowest segment masses of the three groups (p < 0.05). Elite male swimmers recorded the greatest inertial parameters of the trunk and upper arms (p < 0.05). Using the DXA method as the criterion, the five indirect methods produced errors greater than 10% for at least one BSIP in all three populations. Therefore, caution is required when computing BSIPs for elite swimmers via these indirect methods, DXA accurately estimated BSIPs in the frontal plane. Key Points Elite swimmers have significantly different body segment inertial parameters than young adult Caucasian males. The errors computed from indirect BSIP estimation methods are large regardless whether applied to elite swimmers or young adult Caucasian males. No indirect estimation method consistently performed best. PMID:24421737

  17. Dual Energy X-Ray Absorptiometry Compared with Anthropometry in Relation to Cardio-Metabolic Risk Factors in a Young Adult Population: Is the ‘Gold Standard’ Tarnished?

    PubMed Central

    Hands, Beth; Pennell, Craig E.; Lye, Stephen J.; Mountain, Jennifer A.

    2016-01-01

    Background and Aims Assessment of adiposity using dual energy x-ray absorptiometry (DXA) has been considered more advantageous in comparison to anthropometry for predicting cardio-metabolic risk in the older population, by virtue of its ability to distinguish total and regional fat. Nonetheless, there is increasing uncertainty regarding the relative superiority of DXA and little comparative data exist in young adults. This study aimed to identify which measure of adiposity determined by either DXA or anthropometry is optimal within a range of cardio-metabolic risk factors in young adults. Methods and Results 1138 adults aged 20 years were assessed by DXA and standard anthropometry from the Western Australian Pregnancy Cohort (Raine) Study. Cross-sectional linear regression analyses were performed. Waist to height ratio was superior to any DXA measure with HDL-C. BMI was the superior model in relation to blood pressure than any DXA measure. Midriff fat mass (DXA) and waist circumference were comparable in relation to glucose. For all the other cardio-metabolic variables, anthropometric and DXA measures were comparable. DXA midriff fat mass compared with BMI or waist hip ratio was the superior measure for triglycerides, insulin and HOMA-IR. Conclusion Although midriff fat mass (measured by DXA) was the superior measure with insulin sensitivity and triglycerides, the anthropometric measures were better or equal with various DXA measures for majority of the cardio-metabolic risk factors. Our findings suggest, clinical anthropometry is generally as useful as DXA in the evaluation of the individual cardio-metabolic risk factors in young adults. PMID:27622523

  18. Body composition in young female eating-disorder patients with severe weight loss and controls: evidence from the four-component model and evaluation of DXA

    PubMed Central

    Wells, J C K; Haroun, D; Williams, J E; Nicholls, D; Darch, T; Eaton, S; Fewtrell, M S

    2015-01-01

    Background/Objectives: Whether fat-free mass (FFM) and its components are depleted in eating-disorder (ED) patients is uncertain. Dual energy X-ray absorptiometry (DXA) is widely used to assess body composition in pediatric ED patients; however, its accuracy in underweight populations remains unknown. We aimed (1) to assess body composition of young females with ED involving substantial weight loss, relative to healthy controls using the four-component (4C) model, and (2) to explore the validity of DXA body composition assessment in ED patients. Subjects/Methods: Body composition of 13 females with ED and 117 controls, aged 10–18 years, was investigated using the 4C model. Accuracy of DXA for estimation of FFM and fat mass (FM) was tested using the approach of Bland and Altman. Results: Adjusting for age, height and pubertal stage, ED patients had significantly lower whole-body FM, FFM, protein mass (PM) and mineral mass (MM) compared with controls. Trunk and limb FM and limb lean soft tissue were significantly lower in ED patients. However, no significant difference in the hydration of FFM was detected. Compared with the 4C model, DXA overestimated FM by 5±36% and underestimated FFM by 1±9% in ED patients. Conclusion: Our study confirms that ED patients are depleted not only in FM but also in FFM, PM and MM. DXA has limitations for estimating body composition in individual young female ED patients. PMID:26173868

  19. BMI and an Anthropometry-Based Estimate of Fat Mass Percentage Are Both Valid Discriminators of Cardiometabolic Risk: A Comparison with DXA and Bioimpedance

    PubMed Central

    Völgyi, Eszter; Savonen, Kai; Tylavsky, Frances A.; Alén, Markku; Cheng, Sulin

    2013-01-01

    Objective. To determine whether categories of obesity based on BMI and an anthropometry-based estimate of fat mass percentage (FM% equation) have similar discriminative ability for markers of cardiometabolic risk as measurements of FM% by dual-energy X-ray absorptiometry (DXA) or bioimpedance analysis (BIA). Design and Methods. A study of 40–79-year-old male (n = 205) and female (n = 388) Finns. Weight, height, blood pressure, triacylglycerols, HDL cholesterol, and fasting blood glucose were measured. Body composition was assessed by DXA and BIA and a FM%-equation. Results. For grade 1 hypertension, dyslipidaemia, and impaired fasting glucose >6.1 mmol/L, the categories of obesity as defined by BMI and the FM% equation had 1.9% to 3.7% (P < 0.01) higher discriminative power compared to DXA. For grade 2 hypertension the FM% equation discriminated 1.2% (P = 0.05) lower than DXA and 2.8% (P < 0.01) lower than BIA. Receiver operation characteristics confirmed BIA as best predictor of grade 2 hypertension and the FM% equation as best predictor of grade 1 hypertension. All other differences in area under curve were small (≤0.04) and 95% confidence intervals included 0. Conclusions. Both BMI and FM% equations may predict cardiometabolic risk with similar discriminative ability as FM% measured by DXA or BIA. PMID:24455216

  20. DXA femoral neck strength analysis in Chinese overweight and normal weight adolescents.

    PubMed

    Gong, Jian; Xu, Yi; Guo, Bin; Xu, Hao

    2012-01-01

    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.

  1. Accuracy and the influence of marrow fat on quantitative CT and dual-energy X-ray absorptiometry measurements of the femoral neck in vitro.

    PubMed

    Kuiper, J W; van Kuijk, C; Grashuis, J L; Ederveen, A G; Schütte, H E

    1996-01-01

    Bone mineral measurements with quantitative computed tomography (QCT) and dual-energy X-ray absorptiometry (DXA) were compared with chemical analysis (ChA) to determine (1) the accuracy and (2) the influence of bone marrow fat. Total bone mass of 19 human femoral necks in vitro was determined with QCT and DXA before and after defatting. ChA consisted of defatting and decalcification of the femoral neck samples for determination of bone mineral mass (BmM) and amount of fat. The mean BmM was 4.49 g. Mean fat percentage was 37.2% (23.3%-48.5%). QCT, DXA and ChA before and after defatting were all highly correlated (r > 0.96, p < 0.0001). Before defatting the QCT values were on average 0.35 g less than BmM and the DXA values were on average 0.65 g less than BmM. After defatting, all bone mass values increased; QCT values were on average 0.30 g more than BmM and DXA values were 0.29 g less than BmM. It is concluded that bone mineral measurements of the femoral neck with QCT and DXA are highly correlated with the chemically determined bone mineral mass and that both techniques are influenced by the femoral fat content.

  2. Periprosthetic DXA after total hip arthroplasty with short vs. ultra-short custom-made femoral stems

    PubMed Central

    Santori, Francesco S; Pavan, Laura; Learmonth, Ian D; Passariello, Roberto

    2009-01-01

    Background and purpose Dual-energy X-ray absorptiometry (DXA) analysis of the 7 periprosthetic Gruen zones is the most commonly used protocol to evaluate bone remodeling after the implantation of conventional femoral stems. We assessed the value of DXA after cementless primary total hip arthroplasty (THA) by comparing the effect of progressive shortening of the stem of two femoral implants on periprosthetic bone remodeling using a specifically developed protocol of analysis with 5 periprosthetic regions of interest (ROIs). Patients and methods Bone mineral density (BMD) was evaluated in 37 patients in the plateau stage, 3 years after THA. Two femoral implants featuring conceptually new designs and surgical technique were tested: types 1 and 2, characterized by extremely short stem and virtual absence of distal stem, respectively. Results We found that progressive shortening of the femoral stem produces more proximal loading, which effectively preserves metaphyseal bone stock and increases periprosthetic BMD in the medial ROIs over time. In the type 2 group, higher absolute BMD values were observed in medial ROIs 4 and 5. No differences were found in ROIs 1, 2, and 3. Interpretation This study shows the flexibility of DXA in adapting the protocol of periprosthetic analysis to the specific requirements of new implant designs, and it shows its high sensitivity in evaluation of the biological response of bone to changes in implant shape. PMID:19562565

  3. Concurrent validity of the BOD POD and dual energy x-ray absorptiometry techniques for assessing body composition in young women.

    PubMed

    Maddalozzo, Gianni F; Cardinal, Bradley J; Snow, Christine A

    2002-11-01

    The purpose of this study was to determine the concurrent validity of the BOD POD (BP) (Life Measurement Instruments) and Dual Energy X-Ray Absorptiometry (DXA) Elite 4500A (Hologic, Inc.) techniques for assessing the body fat percentage of young women. The participants were forty-three white college-aged women (19.4 +/- 1.4 years) with a BMI of 23.4 +/- 2.3. Both body composition analyses were completed on the same day and were taken within 10 minutes of each other. Body fat percentage was estimated to be 24.3 (SE = 1.1) and 23.8 (SE = 0.8) using the BP and DXA techniques, respectively. Exact matches, in terms of body fat percentage, were obtained for 10 of the 43 participants (23.3%). In conclusion, our data supports the concurrent validity of the BP and DXA techniques for assessing body fat in young women.

  4. Does Visceral Fat Estimated by Dual-Energy X-ray Absorptiometry Independently Predict Cardiometabolic Risks in Adults?

    PubMed Central

    Sasai, Hiroyuki; Brychta, Robert J.; Wood, Rachel P.; Rothney, Megan P.; Zhao, Xiongce; Skarulis, Monica C.; Chen, Kong Y.

    2015-01-01

    Background: Abdominal visceral fat, typically measured by computer tomography (CT) or magnetic resonance imaging (MRI), has been shown to correlate with cardiometabolic risks. The purpose of this study was to examine whether a newly developed and validated visceral fat measurement from dual-energy X-ray absorptiometry (DXA) provides added predictive value to the cross-sectional differences of cardiometabolic parameters beyond the traditional anthropometric and DXA adiposity parameters. Method: A heterogeneous cohort of 194 adults (81 males and 113 females) with a BMI of 19 to 54 kg/m2 participated in this cross-sectional study. Body composition was measured with a DXA densitometer. Visceral fat was then computed with a proprietary algorithm. Insulin sensitivity index (SI, measured by intravenous glucose tolerance test), blood pressures, and lipid profiles, and peak oxygen uptake were also measured as cardiometabolic risk parameters. Results: DXA-estimated visceral fat mass was associated with HDL cholesterol (regression coefficient [β] = −5.15, P < .01, adjusted R2 = .21), triglyceride (β = 26.01, P < .01, adjusted R2 = .14), and peak oxygen uptake (β = −3.15, P < .01, adjusted R2 = .57) after adjusting for age, gender, and ethnicity. A subanalysis stratifying gender-specific BMI tertiles showed visceral fat, together with ethnicity, was independently associated with SI in overweight men and moderately obese women (second tertile). Conclusions: Without requiring additional CT or MRI-based measurements, visceral fat detected by DXA might offer certain advantages over the traditional DXA adiposity parameters as means of assessing cardiometabolic risks. PMID:25802470

  5. DXA, bioelectrical impedance, ultrasonography and biometry for the estimation of fat and lean mass in cats during weight loss

    PubMed Central

    2012-01-01

    Background Few equations have been developed in veterinary medicine compared to human medicine to predict body composition. The present study was done to evaluate the influence of weight loss on biometry (BIO), bioimpedance analysis (BIA) and ultrasonography (US) in cats, proposing equations to estimate fat (FM) and lean (LM) body mass, as compared to dual energy x-ray absorptiometry (DXA) as the referenced method. For this were used 16 gonadectomized obese cats (8 males and 8 females) in a weight loss program. DXA, BIO, BIA and US were performed in the obese state (T0; obese animals), after 10% of weight loss (T1) and after 20% of weight loss (T2). Stepwise regression was used to analyze the relationship between the dependent variables (FM, LM) determined by DXA and the independent variables obtained by BIO, BIA and US. The better models chosen were evaluated by a simple regression analysis and means predicted vs. determined by DXA were compared to verify the accuracy of the equations. Results The independent variables determined by BIO, BIA and US that best correlated (p < 0.005) with the dependent variables (FM and LM) were BW (body weight), TC (thoracic circumference), PC (pelvic circumference), R (resistance) and SFLT (subcutaneous fat layer thickness). Using Mallows’Cp statistics, p value and r2, 19 equations were selected (12 for FM, 7 for LM); however, only 7 equations accurately predicted FM and one LM of cats. Conclusions The equations with two variables are better to use because they are effective and will be an alternative method to estimate body composition in the clinical routine. For estimated lean mass the equations using body weight associated with biometrics measures can be proposed. For estimated fat mass the equations using body weight associated with bioimpedance analysis can be proposed. PMID:22781317

  6. MRI-measured bone marrow adipose tissue is inversely related to DXA-measured bone mineral in Caucasian women

    PubMed Central

    Chen, J.; Punyanitya, M.; Shapses, S.; Heshka, S.; Heymsfield, S. B.

    2007-01-01

    Introduction Recent studies suggest that bone marrow adipose tissue (BMAT) might play a role in the pathogenesis of osteoporosis. Previous research using regional magnetic resonance spectroscopy methods to measure BMAT has reported inconsistent findings on the relationship between BMAT and dual-energy absorptiometry (DXA)-measured bone mineral density (BMD). Methods In the present study, total body and pelvic BMAT were evaluated in 56 healthy women (age 18–88 yrs, mean±SD, 47.4±17.6 yrs; BMI, 24.3±4.2 kg/m2) with T1-weighted whole-body magnetic resonance imaging (MRI). BMD was measured using the whole-body DXA mode (GE Lunar DPX, software version 4.7). Results A strong negative correlation was observed between pelvic BMAT and BMD (total-body BMD, R=− 0.743, P<0.001; pelvic BMD, R=− 0.646, P<0.001), and between total-body BMAT and BMD (total-body BMD, R=− 0.443, P<0.001; pelvic BMD, R=− 0.308, P < 0.001). The inverse association between pelvic BMAT and BMD remained strong after adjusting for age, weight, total body fat, and menopausal status (partial correlation: total-body BMD, R=− 0.553, P< 0.001; pelvic BMD, R=− 0.513, P<0.001). BMAT was also highly correlated with age (pelvic BMAT, R=0.715, P< 0.001; total-body BMAT, R=0.519, P<0.001). Conclusion MRI-measured BMAT is thus strongly inversely correlated with DXA-measured BMD independent of other predictor variables. These observations, in the context of DXA technical concerns, support the growing evidence linking BMAT with low bone density. PMID:17139464

  7. Total body composition by dual-photon (153Gd) absorptiometry

    SciTech Connect

    Mazess, R.B.; Peppler, W.W.; Gibbons, M.

    1984-10-01

    The lean-fat composition (%FATR) of soft tissue and the mineral mass of the skeleton were determined in vivo using dual-photon (153Gd) absorptiometry (dose under 2 mrem). A rectilinear raster scan was made over the entire body in 18 subjects (14 female, 4 male). Single-photon absorptiometry (125I) measured bone mineral content on the radius. Percentage fat (%FATD) was determined in the same subjects using body density (from underwater weighing with correction for residual lung volume). Lean body mass (LBM) was determined using both %FATR and %FATD. Percentage fat from absorptiometry and from underwater density were correlated (r . 0.87). The deviation of %FATD from %FATR was due to the amount of skeletal mineral as a percentage of the LBM (r . 0.90). Therefore, skeletal variability, even in normal subjects, where mineral ranges only from 4 to 8% of the LBM, essentially precludes use of body density as a composition indicator unless skeletal mass is measured. Anthropometry (fatfolds and weight) predicted %FATR and LBM at least as well as did underwater density. The predictive error of %FATR from fatfolds was 5% while the predictive error in predicting LBM from anthropometry was 2 to 3 kg (3%).

  8. Total body carbon and oxygen masses: evaluation of dual-energy x-ray absorptiometry estimation by in vivo neutron activation analysis

    NASA Astrophysics Data System (ADS)

    Wang, ZiMian; Pierson, Richard N., Jr.

    2010-10-01

    Oxygen and carbon are the first and second abundant elements, respectively, in the human body by mass. Although many physiological and pathological processes are accompanied with alteration of total body oxygen (TBO) and carbon (TBC) masses, in vivo measurements of the two elements are limited. Up to now, almost all available information of TBC and TBO is based on in vivo neutron activation (IVNA) analysis which is very expensive and involves moderate radiation exposure. The aim of the present study was to develop and evaluate an alternative strategy for TBC and TBO estimation. Mechanistic models were derived for predicting TBC and TBO masses from dual-energy x-ray absorptiometry (DXA) and total body water (TBW). Twenty-eight adult subjects were studied. IVNA-measured TBC and TBO masses were used as the criterion. TBC masses predicted by DXA-alone and by DXA-TBW models were 20.8 ± 7.1 kg and 20.6 ± 6.8 kg, respectively, close to the IVNA-measured value (19.5 ± 6.3 kg). There were strong correlations (both with r > 0.95, P < 0.001) between the predicted and measured TBC masses. TBO masses predicted by DXA-alone and by DXA-TBW models were 46.0 ± 9.8 kg and 46.5 ± 9.9 kg, respectively, close to the IVNA-measured value (48.0 ± 10.4 kg). Correlations (both with r > 0.97, P < 0.001) were strong between the predicted and measured TBO masses. Bland-Altman analysis validated the applicability of DXA-based models to predict TBC and TBO masses. As both DXA and TBW dilutions are widely available, low-risk, low-cost techniques, the present study provides a safe and practical method for estimating elemental composition in vivo.

  9. Relationship between dual-energy X-ray absorptiometry volumetric assessment and X-ray computed tomography-derived single-slice measurement of visceral fat.

    PubMed

    Xia, Yi; Ergun, David L; Wacker, Wynn K; Wang, Xin; Davis, Cynthia E; Kaul, Sanjiv

    2014-01-01

    To reduce radiation exposure and cost, visceral adipose tissue (VAT) measurement on X-ray computed tomography (CT) has been limited to a single slice. Recently, the US Food and Drug Administration has approved a dual-energy X-ray absorptiometry (DXA) application validated against CT to measure VAT volume. The purpose of this study was to develop an algorithm to compute single-slice area values on DXA at 2 common landmarks, L2/3 and L4/5, from an automated volumetrically derived measurement of VAT. Volumetric CT and total body DXA were measured in 55 males (age: 21-77 yr; body mass index [BMI]: 21.1-37.9) and 60 females (age: 21-85 yr; BMI: 20.0-39.7). Equations were developed by applying the relationship of CT single-slice area and volume measurements of VAT to the DXA VAT volume measure as well as validating these against the CT single-slice measurements. Correlation coefficients between DXA estimate of single-slice area and CT were 0.94 for L2/3 and 0.96 for L4/5. The mean difference between DXA estimate of single-slice area and CT was 5 cm(2) at L2/3 and 3.8 cm(2) at L4/5. Bland-Altman analysis showed a fairly constant difference across the single-slice range in this study, and the 95% limits of agreement for the 2 methods were -44.6 to +54.6 cm(2) for L2/3 and -47.3 to +54.9 cm(2) for L4/5. In conclusion, a volumetric measurement of VAT by DXA can be used to estimate single-slice measurements at the L2/3 and the L4/5 landmarks.

  10. Air Displacement Plethysmography versus Dual-Energy X-Ray Absorptiometry in Underweight, Normal-Weight, and Overweight/Obese Individuals

    PubMed Central

    Lowry, David W.; Tomiyama, A. Janet

    2015-01-01

    Background Accurately estimating fat percentage is important for assessing health and determining treatment course. Methods of estimating body composition such as hydrostatic weighing or dual-energy x-ray absorptiometry (DXA), however, can be expensive, require extensive operator training, and, in the case of hydrostatic weighing, be highly burdensome for patients. Our objective was to evaluate air displacement plethysmography via the Bod Pod, a less burdensome method of estimating body fat percentage. In particular, we filled a gap in the literature by testing the Bod Pod at the lower extreme of the Body Mass Index (BMI) distribution. Findings Three BMI groups were recruited and underwent both air displacement plethysmography and dual-energy x-ray absorptiometry. We recruited 30 healthy adults at the lower BMI distribution from the Calorie Restriction (CR) Society and followers of the CR Way. We also recruited 15 normal weight and 19 overweight/obese healthy adults from the general population. Both Siri and Brozek equations derived body fat percentage from the Bod Pod, and Bland-Altman analyses assessed agreement between the Bod Pod and DXA. Compared to DXA, the Bod Pod overestimated body fat percentage in thinner participants and underestimated body fat percentage in heavier participants, and the magnitude of difference was larger for underweight BMI participants, reaching 13% in some. The Bod Pod and DXA had smaller discrepancies in normal weight and overweight/obese participants. Conclusions While less burdensome, clinicians should be aware that Bod Pod estimates may deviate from DXA estimates particularly at the lower end of the BMI distribution. PMID:25607661

  11. SCAN+

    SciTech Connect

    Kenneth Krebs, John Svoboda

    2009-11-01

    SCAN+ is a software application specifically designed to control the positioning of a gamma spectrometer by a two dimensional translation system above spent fuel bundles located in a sealed spent fuel cask. The gamma spectrometer collects gamma spectrum information for the purpose of spent fuel cask fuel loading verification. SCAN+ performs manual and automatic gamma spectrometer positioning functions as-well-as exercising control of the gamma spectrometer data acquisitioning functions. Cask configuration files are used to determine the positions of spent fuel bundles. Cask scanning files are used to determine the desired scan paths for scanning a spent fuel cask allowing for automatic unattended cask scanning that may take several hours.

  12. Utilization of DXA Bone Mineral Densitometry in Ontario

    PubMed Central

    2006-01-01

    Executive Summary Issue Systematic reviews and analyses of administrative data were performed to determine the appropriate use of bone mineral density (BMD) assessments using dual energy x-ray absorptiometry (DXA), and the associated trends in wrist and hip fractures in Ontario. Background Dual Energy X-ray Absorptiometry Bone Mineral Density Assessment Dual energy x-ray absorptiometry bone densitometers measure bone density based on differential absorption of 2 x-ray beams by bone and soft tissues. It is the gold standard for detecting and diagnosing osteoporosis, a systemic disease characterized by low bone density and altered bone structure, resulting in low bone strength and increased risk of fractures. The test is fast (approximately 10 minutes) and accurate (exceeds 90% at the hip), with low radiation (1/3 to 1/5 of that from a chest x-ray). DXA densitometers are licensed as Class 3 medical devices in Canada. The World Health Organization has established criteria for osteoporosis and osteopenia based on DXA BMD measurements: osteoporosis is defined as a BMD that is >2.5 standard deviations below the mean BMD for normal young adults (i.e. T-score <–2.5), while osteopenia is defined as BMD that is more than 1 standard deviation but less than 2.5 standard deviation below the mean for normal young adults (i.e. T-score< –1 & ≥–2.5). DXA densitometry is presently an insured health service in Ontario. Clinical Need   Burden of Disease The Canadian Multicenter Osteoporosis Study (CaMos) found that 16% of Canadian women and 6.6% of Canadian men have osteoporosis based on the WHO criteria, with prevalence increasing with age. Osteopenia was found in 49.6% of Canadian women and 39% of Canadian men. In Ontario, it is estimated that nearly 530,000 Ontarians have some degrees of osteoporosis. Osteoporosis-related fragility fractures occur most often in the wrist, femur and pelvis. These fractures, particularly those in the hip, are associated with increased

  13. The Ability of Lumbar Spine DXA and Phalanx QUS to Detect Previous Fractures in Young Thalassemic Patients With Hypogonadism, Hypothyroidism, Diabetes, and Hepatitis-B: A 2-Year Subgroup Analysis From the Taranto Area of Apulia Region

    PubMed Central

    Neglia, Cosimo; Peluso, Angelo; di Rosa, Salvatore; Ferrarese, Antonio; Di Tanna, Gianluca; Caiaffa, Vincenzo; Benvenuto, Marco; Cozma, Alexandru; Chitano, Giovanna; Agnello, Nadia; Paladini, Daniele; Baldi, Nicola; Distante, Alessandro; Piscitelli, Prisco

    2013-01-01

    Background: Osteoporosis is a leading cause of morbidity in patients affected by β-thalassemia major or intermediate; we aimed to assess the association between demineralization observed in young thalassemic patients. Methods: A total of 88 patients with β-thalassemia were recruited at Microcitemia Center of Taranto Hospital under the Prevention Osteoporosis and Fractures research project from 2008 to 2010. All the patients were screened with both dual energy x-ray absorptiometry (DXA) and quantitative ultrasound (QUS). T score and Z score values were obtained for each subject. Results: The overall prevalence of demineralization was 84% with DXA and 70% with QUS, whereas normality was found in 16% of patients screened with DXA and in 30% of cases with QUS. Hypogonadism, hypothyroidism, diabetes mellitus, hepatitis-B, and the presence of previous fragility fractures were significantly associated with the demineralization status (lower T scores values) both with DXA and QUS. Conclusion: Our data confirm that DXA and QUS examinations are both useful for detecting bone demineralization in thalassemic patients. PMID:23652868

  14. Comparison of nuclear magnetic resonance spectroscopy with dual-photon absorptiometry and dual-energy X-ray absorptiometry in the measurement of thoracic vertebral bone mineral density: compressive force versus bone mineral.

    PubMed

    Myers, T J; Battocletti, J H; Mahesh, M; Gulati, M; Wilson, C R; Pintar, F; Reinartz, J

    1994-05-01

    31P nuclear magnetic resonance spectroscopy (NMRS) measurements were made on human T2 and T3 vertebral bodies. The bone mineral content (BMC) of isolated vertebral bodies minus the posterior elements and disks was measured using (1) NMRS on a 3.5 T, 85 mm bore GE Medical Systems NT-150 superconducting spectrometer, (2) a Lunar Corporation DPX-L dual-energy X-ray absorptiometry (DXA) scanner in an anterior-posterior (AP) orientation, (3) a Norland Corporation XR26 DXA scanner, also in an AP direction, and (4) a Norland Corporation model 2600 dual-photon absorptiometry (DPA) densitometer in both the AP and superior-inferior (SI) directions. Vertebral body volumes were measured using a water displacement technique to determine volume bone mineral densities (VBMD). They were then compressed to failure using an electrohydraulic testing device, followed by ashing in a muffle furnace at 700 degrees C for 18 h. Correlations of BMC between NMRS and DPA, DXA and ashing were excellent (0.96 < or = r < or = 0.99); in a one-way analysis of variance (ANOVA) test, means were not statistically different at a p level of 0.757. The correlations of VBMD between NMRS and the other methods were not as good (0.83 < or = r < or = 0.95); in a one-way ANOVA test, means were not statistically different at a p level of 0.089. BMC was a better predictor of ultimate compressive failure than VBMD for all six methods. For NMRS, the regression coefficient for BMC was r2 = 0.806, compared with r2 = 0.505 for VBMD. NMRS may prove an alternative to present methods of determining bone mineral. PMID:8069051

  15. Executive Summary of the 2015 ISCD Position Development Conference on Advanced Measures From DXA and QCT: Fracture Prediction Beyond BMD.

    PubMed

    Shepherd, John A; Schousboe, John T; Broy, Susan B; Engelke, Klaus; Leslie, William D

    2015-01-01

    There have been many scientific advances in fracture risk prediction beyond bone density. The International Society for Clinical Densitometry (ISCD) convened a Position Development Conference (PDC) on the use of dual-energy X-ray absorptiometry beyond measurement of bone mineral density for fracture risk assessment, including trabecular bone score and hip geometry measures. Previously, no guidelines for nonbone mineral density DXA measures existed. Furthermore, there have been advances in the analysis of quantitative computed tomography (QCT) including finite element analysis, QCT of the hip, DXA-equivalent hip measurements, and opportunistic screening that were not included in the previous ISCD positions. The topics and questions for consideration were developed by the ISCD Board of Directors and the Scientific Advisory Committee and were designed to address the needs of clinical practitioners. Three task forces were created and asked to conduct comprehensive literature reviews to address specific questions. The task forces included participants from many countries and a variety of interests including academic institutions and private health care delivery organizations. Representatives from industry participated as consultants to the task forces. Task force reports with proposed position statements were then presented to an international panel of experts with backgrounds in bone densitometry. The PDC was held in Chicago, Illinois, USA, contemporaneously with the Annual Meeting of the ISCD, February 26 through February 28, 2015. This Executive Summary describes the methodology of the 2015 PDC on advanced measures from DXA and QCT and summarizes the approved official positions. Six separate articles in this issue will detail the rationale, discussion, and additional research topics for each question the task forces addressed.

  16. Measuring body composition in dogs using multifrequency bioelectrical impedance analysis and dual energy X-ray absorptiometry.

    PubMed

    Rae, L S; Vankan, D M; Rand, J S; Flickinger, E A; Ward, L C

    2016-06-01

    Thirty-five healthy, neutered, mixed breed dogs were used to determine the ability of multifrequency bioelectrical impedance analysis (MFBIA) to predict accurately fat-free mass (FFM) in dogs using dual energy X-ray absorptiometry (DXA)-measured FFM as reference. A second aim was to compare MFBIA predictions with morphometric predictions. MFBIA-based predictors provided an accurate measure of FFM, within 1.5% when compared to DXA-derived FFM, in normal weight dogs. FFM estimates were most highly correlated with DXA-measured FFM when the prediction equation included resistance quotient, bodyweight, and body condition score. At the population level, the inclusion of impedance as a predictor variable did not add substantially to the predictive power achieved with morphometric variables alone; in individual dogs, impedance predictors were more valuable than morphometric predictors. These results indicate that, following further validation, MFBIA could provide a useful tool in clinical practice to objectively measure FFM in canine patients and help improve compliance with prevention and treatment programs for obesity in dogs.

  17. SCAN+

    2009-11-01

    SCAN+ is a software application specifically designed to control the positioning of a gamma spectrometer by a two dimensional translation system above spent fuel bundles located in a sealed spent fuel cask. The gamma spectrometer collects gamma spectrum information for the purpose of spent fuel cask fuel loading verification. SCAN+ performs manual and automatic gamma spectrometer positioning functions as-well-as exercising control of the gamma spectrometer data acquisitioning functions. Cask configuration files are used to determinemore » the positions of spent fuel bundles. Cask scanning files are used to determine the desired scan paths for scanning a spent fuel cask allowing for automatic unattended cask scanning that may take several hours.« less

  18. Assessment of bone mineral density by DXA and the trabecular microarchitecture of the calcaneum by texture analysis in pre- and postmenopausal women in the evaluation of osteoporosis.

    PubMed

    Karunanithi, R; Ganesan, S; Panicker, T M R; Korath, M Paul; Jagadeesan, K

    2007-10-01

    The in vivo evaluation of trabecular bone structure could be useful in the diagnosis of osteoporosis for the characterization of therapeutic response and understanding the role of parameters other than bone mineral density (BMD) in defining skeletal status. This study was made to evaluate changes taking place in the trabecular architecture of bone with age and menopausal status in women. The findings are compared with the femoral neck bone as well as the trochantar bone mineral density determined by dual energy X-ray absorptiometry (DXA), which is a standard reference test for evaluation of osteoporosis. Seventy females were recruited for the study, 25 premenopausal (mean age ± SD: 39.4 ± 3.8) and 45 postmenopausal (mean age ± SD: 57.9 ± 7.9) women. The right femoral neck bone mineral density was measured for them by dual energy X-ray absorptiometry (DXA). For the same individuals, lateral view radiographs of the right calcaneum were taken as well. The radiographs were digitized and the region of interest (ROI) of 256 × 256 pixels was selected, the run length matrix was computed for calculating seven parameters [Table 1] and the two dimensional fast Fourier transform of the image was calculated. Using the FFT, the power spectral density (PSD) was derived and the root mean square (RMS) value was determined. Our results confirm that age has a significant influence on the texture of the trabecular bone and bone mineral density. PMID:21224926

  19. Air displacement plethysmography, dual-energy X-ray absorptiometry, and total body water to evaluate body composition in preschool-age children.

    PubMed

    Crook, Tina A; Armbya, Narain; Cleves, Mario A; Badger, Thomas M; Andres, Aline

    2012-12-01

    Anthropometrics and body mass index are only proxies in the evaluation of adiposity in the pediatric population. Air displacement plethysmography technology was not available for children aged 6 months to 9 years until recently. Our study was designed to test the precision of air displacement plethysmography (ADP) in measuring body fat mass in children at ages 3 to 5 years compared with a criterion method, deuterium oxide dilution (D(2)O), which estimates total body water and a commonly used methodology, dual-energy x-ray absorptiometry (DXA). A prospective, cross-sectional cohort of 66 healthy children (35 girls) was recruited in the central Arkansas region between 2007 and 2009. Weight and height were obtained using standardized procedures. Fat mass (%) was measured using ADP, DXA, and D(2)O. Concordance correlation coefficient and Bland-Altman plots were used to investigate the precision of the ADP techniques against D(2)O and DXA in children at ages 3 to 5 years. ADP concordance correlation coefficient for fat mass was weak (0.179) when compared with D(2)O. Bland-Altman plots revealed a low accuracy and large scatter of ADP fat mass (%) results (mean=-2.5, 95% CI -20.3 to 15.4) compared with D(2)O. DXA fat mass (%) results were more consistent although DXA systematically overestimated fat mass by 4% to 5% compared with D(2)O. Compared with D(2)O, ADP does not accurately assess percent fat mass in children aged 3 to 5 years. Thus, D(2)O, DXA, or quantitative nuclear magnetic resonance may be considered better options for assessing fat mass in young children.

  20. Agreement between bioelectrical impedance and dual energy X-ray absorptiometry in assessing fat, lean and bone mass changes in adults after a lifestyle intervention.

    PubMed

    Macfarlane, Duncan J; Chan, Natalie T-Y; Tse, Michael A; Joe, Glen M

    2016-01-01

    We aimed to assess the agreement of a commercially available bioelectrical impedance analysis (BIA) device in measuring changes in fat, lean and bone mass over a 10-week lifestyle intervention, with dual energy X-ray absorptiometry (DXA) as reference. A sample of 136 volunteers (18-66 years) underwent a physical activity intervention to enhance lean mass and reduce fat mass. BIA (Tanita BC545) and DXA (Hologic Explorer) measures of whole-body composition were taken at baseline and at the end of the intervention. After an average of 74 ± 18 days intervention, DXA showed significant changes in 2 of 3 outcome variables: reduced fat mass of 0.802 ± 1.092 kg (P < 0.001), increased lean mass of 0.477 ± 0.966 kg (P < 0.001); minor non-significant increase of 0.007 ± 0.041 kg of bone mass (P = 0.052). The respective changes in BIA measures were a significant reduction of 0.486 ± 1.539 kg fat (P < 0.001), but non-significant increases of 0.084 ± 1.201 kg lean mass (P = 0.425), and 0.014 ± 0.091 kg bone (P = 0.074). Significant, but moderately weak, correlations were seen in absolute mass changes between DXA and BIA: 0.511 (fat), 0.362 (lean) and 0.172 (bone). Compared to DXA, BIA demonstrated mediocre agreement to changes in fat mass, but poor agreement to lean mass changes. BIA significantly underestimated the magnitude of changes in fat and lean mass compared to DXA.

  1. Bone mineral density referral for dual-energy X-ray absorptiometry using quantitative ultrasound as a prescreening tool in postmenopausal women from the general population: a cost-effectiveness analysis.

    PubMed

    Marín, F; López-Bastida, J; Díez-Pérez, A; Sacristán, J A

    2004-03-01

    The aim of our study was to assess, from the perspective of the National Health Services in Spain, the cost-effectiveness of quantitative ultrasound (QUS) as a prescreen referral method for bone mineral density (BMD) assessment by dual-energy X-ray absorptiometry (DXA) in postmenopausal women of the general population. Using femoral neck DXA and heel QUS. We evaluated 267 consecutive postmenopausal women 65 years and older and attending primary care physician offices for any medical reason. Subjects were classified as osteoporotic or nonosteoporotic (normal or osteopenic) using the WHO definition for DXA. Effectiveness was assessed in terms of the sensitivity and specificity of the referral decisions based on the QUS measurement. Local costs were estimated from health services and actual resource used. Cost-effectiveness was evaluated in terms of the expected cost per true positive osteoporotic case detected. Baseline prevalence of osteoporosis evaluated by DXA was 55.8%. The sensitivity and specificity for the diagnosis of osteoporosis by QUS using the optimal cutoff thresholds for the estimated heel BMD T-score were 97% and 94%, respectively. The average cost per osteoporotic case detected based on DXA measurement alone was 23.85 euros. The average cost per osteoporotic case detected using QUS as a prescreen was 22.00 euros. The incremental cost-effectiveness of DXA versus QUS was 114.00 euros per true positive case detected. Our results suggest that screening for osteoporosis with QUS while applying strict cufoff values in postmenopausal women of the general population is not substantially more cost-effective than DXA alone for the diagnosis of osteoporosis. However, the screening strategy with QUS may be an option in those circumstances where the diagnosis of osteoporosis is deficient because of the difficulty in accessing DXA equipment.

  2. Comparison of air-displacement plethysmography, hydrodensitometry, and dual X-ray absorptiometry for assessing body composition of children 10 to 18 years of age.

    PubMed

    Lockner, D W; Heyward, V H; Baumgartner, R N; Jenkins, K A

    2000-05-01

    Body density (Db) of 54 boys and girls 10-18 years of age (13.9 +/- 2.4 years) was measured in an air-displacement plethysmograph, the BOD POD, and compared to Db determined by hydrodensitometry (HW). Both Db values were converted to percent body fat (%BF) using a two-component model conversion formula and compared to %BF determined by dual energy X-ray absorptiometry (DXA). Body density estimated from the BOD POD (1.04657 +/- 0.01825 g/cc) was significantly higher than that estimated from HW (1.04032 +/- 0.01872 g/cc). The relative body fat calculated from the BOD POD (23.12 +/- 8.39 %BF) was highly correlated but, on average, 2.9% BF lower than %BF DXA. Average %BF estimates from HW and DXA were not significantly different. Despite consistently underestimating the %BF of children, the strong relationship between DXA and the BOD POD suggests that further investigation may improve the accuracy of the BOD POD for assessing body composition in children.

  3. Bone mineral density test

    MedlinePlus

    ... test; Bone densitometry; DEXA scan; DXA; Dual-energy x-ray absorptiometry; p-DEXA; Osteoporosis-BMD ... common and accurate way uses a dual-energy x-ray absorptiometry (DEXA) scan. DEXA uses low-dose x- ...

  4. Bone mineral density assessment: comparison of dual-energy X-ray absorptiometry measurements at the calcaneus, spine, and hip.

    PubMed

    Sweeney, Ann T; Malabanan, Alan O; Blake, Michael A; Weinberg, Janice; Turner, Adrian; Ray, Patricia; Holick, Michael F

    2002-01-01

    It is widely accepted that bone mineral density (BMD) measurements obtained by dual-energy X-ray absorptiometry (DXA) at the spine, hip, and calcaneus predict fracture risk. Few published studies to date have examined the relationship between pDXA measurements at the calcaneus to those at the hip and spine. It has been demonstrated that T-score-based criteria cannot be universally applied to all skeletal sites and measurement technologies. Our goal was to define the calcaneal T-score threshold equivalent to low bone mass at the hip or spine. A total of 119 female patients between the ages of 33 and 76 yr of age were recruited at Boston University Medical Center for bone densitometry screening. Bone density measurements were obtained at the calcaneus using the portable Norland Apollo Densitometer (Norland Medical Systems, Fort Atkinson, WI) and at the hip and spine using the Norland Eclipse densitometer. By defining a pDXA T-score < or =-1 as a positive test and DXA scores < or =-1 as the presence of low bone mass, we obtained a specificity of 100% and a sensitivity of 73% (positive predictive value 100% and negative predictive value 80%) in detecting low bone mass at the femoral neck in women over age 65 yr. In women between 40 and 65 yr of age, we obtained a sensitivity of 50% and a specificity of 93% (positive predictive value 93% and negative predictive value 50%) in detecting low bone mass at the femoral neck. In women less than 40 yr of age, we obtained a sensitivity of 13% and a specificity of 100% (positive predictive value 100% and negative predictive value 75%) in detecting low bone mass at the femoral neck. From receiver operating characteristic curves, a calcaneal T-score < or =0.0 detects those with a T-score < or =-1 at the femoral neck and lumbar spine with 100% and 85% sensitivity, respectively. Peripheral DXA of the calcaneus is a sensitive and specific test to diagnose low bone mass in women over 65 yr of age. In women under 65 yr of age, this

  5. Dual-energy X-ray absorptiometry, peripheral quantitative computed tomography, and micro-computed tomography techniques are discordant for bone density and geometry measurements in the guinea pig.

    PubMed

    Mak, Ivy L; DeGuire, Jason R; Lavery, Paula; Agellon, Sherry; Weiler, Hope A

    2016-05-01

    This study aims to examine agreement among bone mineral content (BMC) and density (BMD) estimates obtained using dual-energy X-ray absorptiometry (DXA), peripheral quantitative computed tomography (pQCT), and micro-computed tomography (μCT) against high-resolution μCT and bone ash of the guinea pig femur. Middle-aged (n = 40, 86 weeks) male guinea pigs underwent in vivo followed by ex vivo DXA (Hologic QDR 4500A) scanning for intact and excised femur BMC and areal density. To assess bone architecture and strength, excised femurs were scanned on pQCT (Stratec XCT 2000L) as well as on two μCT scanners (LaTheta LCT-200; Skyscan 1174), followed by three-point bending test. Reproducibility was determined using triplicate scans; and agreement assessed using Bland-Altman plots with reference methods being high-resolution μCT (Skyscan) for BMD and bone ashing for BMC. All techniques showed satisfactory ex vivo precision (CV 0.05-4.3 %). However, bias compared to the reference method was highest (207.5 %) in trabecular bone volume fraction (BV/TV) measured by LaTheta, and unacceptable in most total femur and cortical bone measurements. Volumetric BMD (vBMD) and BV/TV derived by LaTheta and pQCT at the distal metaphysis were biased from the Skyscan by an average of 49.3 and 207.5 %, respectively. Variability of vBMD, BV/TV and cross-sectional area at the diaphysis ranged from -5.5 to 30.8 %. LaTheta best quantified total femur BMC with an upper bias of 3.3 %. The observed differences among imaging techniques can be attributable to inherent dissimilarity in construction design, calibration, segmentation and scanning resolution used. These bone imaging tools are precise but are not comparable, at least when assessing guinea pig bones.

  6. Prevalence and predictors of low bone mineral density and fragility fractures among HIV-infected patients at one Italian center after universal DXA screening: sensitivity and specificity of current guidelines on bone mineral density management.

    PubMed

    Mazzotta, Elena; Ursini, Tamara; Agostinone, Adriana; Di Nicola, Angelo Domenico; Polilli, Ennio; Sozio, Federica; Vadini, Francesco; Pieri, Alessandro; Trave, Francesca; De Francesco, Valerio; Capasso, Lorenzo; Borderi, Marco; Manzoli, Lamberto; Viale, Pierluigi; Parruti, Giustino

    2015-04-01

    Low bone mineral density (BMD) is frequent in HIV infection regardless of the use of antiretroviral therapy (ART). Uncertainties remain, however, as to when in HIV infection BMD screening should be performed. We designed a prospective study to estimate the efficacy of universal BMD screening by dual-energy X-ray absorptiometry (DXA). Since April 2009 through March 2011, HIV patients attending our Center were offered femoral/lumbar DXA to screen BMD. Low BMD for chronological age, that is significant osteopenia, was defined as a Z-score ≤ -2.0 at femur and lumbar spine. Nontraumatic bone fractures (NTBFs) were evaluated. The final sample included 163 patients. A Z-score ≤ -2.0 at any site was observed in 19.6% of cases: among these, 18.8% had no indication to DXA using current Italian HIV guidelines for BMD screening. A lower femoral Z-score was independently associated with lower BMI, AIDS diagnosis, HCV co-infection, antiretroviral treatment, and NTBFs; a lower lumbar Z-score with age, BMI, Nadir CD4 T-cell counts, and NTBFs. Prevalence of NTBFs was 27.0%, predictors being male gender, HCV co-infection, and lower femoral Z-scores. Our results suggest that measuring BMD by DXA in all HIV patients regardless of any further specification may help retrieving one-fifth of patients with early BMD disorders not identified using current criteria for selective screening of BMD.

  7. Characteristics of long bone DXA reference data in Hong Kong Chinese.

    PubMed

    Leung, Kwok Sui; Lee, Kwong Man; Cheung, Wing Hoi; Ng, Edmond Siu Woon; Qin, Ling

    2004-01-01

    With the increasing number of geriatric long bone fractures, the establishment of long bone reference BMD data is desirable for the accurate diagnosis of osteoporosis, study of fracture mechanics, implant design, and indications for augmentation of fracture fixation with biomaterials. We report the normal reference bone mineral density (BMD) and bone mineral content (BMC) at three femoral sites (proximal, diaphyseal, and distal) in 106 male and 93 female Hong Kong Chinese aged 12 to 80, measured with dual-energy X-ray absorptiometry (DXA). The length and width of the femur were also measured. The results suggest that males reached peak bone mass earlier than females and the value was also higher in all measured sites. After reaching the peak bone mass, bones lost BMD faster in females. The age-related annual bone loss (in BMD) calculated with a regression model in female subjects were, on average, 3.3, 4.0, and 3.0 times higher than those in males at the diaphyseal, proximal, and distal regions, respectively. The decrease in BMD and BMC occurred slightly earlier in the proximal and distal regions than the diaphysis in both sexes. The male femur was significantly longer than that of the female in all age groups after 20 yr of age and remained unchanged with advancing age. The femoral width in females showed an increasing trend from adolescence. Our study provides reference data for the changes in diaphyseal BMC and BMD associated with aging. The age-related changes in the femoral diameter in females might attenuate the negative impact on fracture risk as a result of decreasing BMD with age.

  8. DXA surrogates for visceral fat are inversely associated with bone density measures in adolescent athletes with menstrual dysfunction

    PubMed Central

    Ackerman, Kathryn E.; Davis, Brittany; Jacoby, Leah; Misra, Madhusmita

    2013-01-01

    Objective Lean mass is associated with bone mineral density (BMD) in athletes, attributable to the anabolic pull of muscle on bone. Fat mass is also important, and subcutaneous fat positively and visceral fat negatively correlates with BMD in obese adolescents. The contribution of regional body composition to low BMD in amenorrheic athletes (AA) has not been elucidated. We hypothesized that in adolescent athletes (runners), BMD is associated positively with total fat (surrogate for subcutaneous fat) and lean mass, and inversely with percent trunk fat and trunk-to-extremity fat ratio (surrogates for visceral fat). Design Cross-sectional study. Subjects and methods We examined BMD and body composition using dual energy X-ray absorptiometry (DXA) in 21 AA and 19 eumenorrheic athletes (EA) (12–18 years) (runners). We report total hip and height-adjusted BMD [lumbar bone mineral apparent density (LBMAD) and whole body bone mineral content/height (WBBMC/Ht)]. Results AA had lower BMD than EA. Lean mass was less strongly associated with hip BMD in AA than EA; fat mass was positively associated with LBMAD in EA. Percent trunk fat and trunk-to-extremity fat ratio were inversely associated with lumbar and WB measures in AA. In a regression model, lean and fat mass were positively, and percent trunk fat and trunk-to-extremity fat ratio negatively associated with LBMAD and WBBMC/Ht for all athletes, even after controlling for serum estradiol. Conclusions DXA surrogates for visceral fat are inversely associated with bone density in athletes. PMID:21932588

  9. Characterization of low bone mass in young patients with thalassemia by DXA, pQCT and markers of bone turnover.

    PubMed

    Fung, Ellen B; Vichinsky, Elliott P; Kwiatkowski, Janet L; Huang, James; Bachrach, Laura K; Sawyer, Aenor J; Zemel, Babette S

    2011-06-01

    Previous reports using dual x-ray absorptiometry (DXA) suggest that up to 70% of adults with thalassemia major (Thal) have low bone mass. However, few studies have controlled for body size and pubertal delay, variables known to affect bone mass in this population. In this study, bone mineral content and areal density (BMC, aBMD) of the spine and whole body were assessed by DXA, and volumetric BMD and cortical geometries of the distal tibia by peripheral quantitative computed tomography (pQCT) in subjects with Thal (n = 25, 11 male, 10 to 30 years) and local controls (n=34, 15 male, 7 to 30 years). Z-scores for bone outcomes were calculated from reference data from a large sample of healthy children and young adults. Fasting blood and urine were collected, pubertal status determined by self-assessment and dietary intake and physical activity assessed by written questionnaires. Subjects with Thal were similar in age, but had lower height, weight and lean mass index Z-scores (all p < 0.001) compared to controls. DXA aBMD was significantly lower in Thal compared to controls at all sites. Adult Thal subjects (> 18 years, n = 11) had lower tibial trabecular vBMD (p = 0.03), cortical area, cortical BMC, cortical thickness, periosteal circumference and section modulus Z-scores (all p < 0.01) compared to controls. Cortical area, cortical BMC, cortical thickness, and periosteal circumference Z-scores (p = 0.02) were significantly lower in young Thal (≤ 18 years, n = 14) compared to controls. In separate multivariate models, tibial cortical area, BMC, and thickness and spine aBMD and whole body BMC Z-scores remained lower in Thal compared to controls after adjustment for gender, lean mass and/or growth deficits (all p < 0.01). Tanner stage was not predictive in these models. Osteocalcin, a marker of bone formation, was significantly reduced in Thal compared to controls after adjusting for age, puberty and whole body BMC (p=0.029). In summary, we have found evidence of

  10. Robust automatic measurement of 3D scanned models for the human body fat estimation.

    PubMed

    Giachetti, Andrea; Lovato, Christian; Piscitelli, Francesco; Milanese, Chiara; Zancanaro, Carlo

    2015-03-01

    In this paper, we present an automatic tool for estimating geometrical parameters from 3-D human scans independent on pose and robustly against the topological noise. It is based on an automatic segmentation of body parts exploiting curve skeleton processing and ad hoc heuristics able to remove problems due to different acquisition poses and body types. The software is able to locate body trunk and limbs, detect their directions, and compute parameters like volumes, areas, girths, and lengths. Experimental results demonstrate that measurements provided by our system on 3-D body scans of normal and overweight subjects acquired in different poses are highly correlated with the body fat estimates obtained on the same subjects with dual-energy X-rays absorptiometry (DXA) scanning. In particular, maximal lengths and girths, not requiring precise localization of anatomical landmarks, demonstrate a good correlation (up to 96%) with the body fat and trunk fat. Regression models based on our automatic measurements can be used to predict body fat values reasonably well.

  11. Associations between pQCT-based fat and muscle area and density and DXA-based total and leg soft tissue mass in healthy women and men

    PubMed Central

    Sherk, Vanessa D; Thiebaud, Robert S; Chen, Zhaojing; Karabulut, Murat; Kim, So Jung; Bemben, Debra A

    2015-01-01

    Peripheral Quantitative Computed Tomography (pQCT) can be used for muscle and fat area and density assessments. These may independently influence muscle and fat mass measurements from Dual Energy X-ray Absorptiometry (DXA). Objective To determine associations between pQCT-derived soft tissue density and area measures and DXA-derived soft tissue mass. Methods Linear regression models were developed based on BMI and calf fat and muscle cross-sectional area (FCSA and MCSA) and density measured by pQCT in healthy women (n=76) and men (n=82) aged 20–59 years. Independent variables for these models were leg and total bone-free lean mass (BFLM) and fat mass (FM) measured by DXA. Results Sex differences (p<0.01) were found in both muscle (Mean±SE: Women: 78.6±0.4; Men: 79.9 ± 0.2 mg/cm3) and fat (Women: 0.8±0.4 Men: 9.1±0.6 mg/cm3) density. BMI, fat density, and age (R2=0.86, p<0.01) best accounted for the variability in total FM. FCSA, BMI, and fat density explained the variance in leg FM (R2=0.87, p<0.01). MCSA and muscle density explained the variance in total (R2=0.65, p<0.01) and leg BFLM (R2=0.70, p<0.01). Conclusion Calf muscle and fat area and density independently predict lean and fat tissue mass. PMID:25524966

  12. Assessing Body Fat of Children by Skinfold Thickness, Bioelectrical Impedance Analysis, and Dual-Energy X-Ray Absorptiometry: A Validation Study Among Malay Children Aged 7 to 11 Years.

    PubMed

    Noradilah, Mohd Jonit; Ang, Yeow Nyin; Kamaruddin, Nor Azmi; Deurenberg, Paul; Ismail, Mohd Noor; Poh, Bee Koon

    2016-07-01

    This study aims to validate skinfold (SKF) and bioelectrical impedance analysis (BIA) against dual-energy X-ray absorptiometry (DXA) in determining body fat percentage (BF%) of Malay children aged 7 to 11 years. A total of 160 children had their BF% assessed using SKF and BIA, with DXA as the criterion method. Four SKF equations (SKFBray, SKFJohnston, SKFSlaughter, and SKFGoran) and 4 BIA equations (BIAManufacturer, BIAHoutkooper, BIARush, and BIAKushner) were used to estimate BF%. Mean age, weight, and height were 9.4 ± 1.1years, 30.5 ± 9.9 kg, and 131.3 ± 8.4 cm. All equations significantly underestimated BF% (P < .05). BIA equations had reasonable agreement with DXA and were independent of BF% with BIAManufacturer being the best equation. Although BIA underestimates BF% as compared with DXA, BIA was more suitable to measure BF% in a population that is similar to this study sample than SKF, suggesting a need to develop new SKF equations that are population specific. PMID:27073201

  13. Assessing Body Fat of Children by Skinfold Thickness, Bioelectrical Impedance Analysis, and Dual-Energy X-Ray Absorptiometry: A Validation Study Among Malay Children Aged 7 to 11 Years.

    PubMed

    Noradilah, Mohd Jonit; Ang, Yeow Nyin; Kamaruddin, Nor Azmi; Deurenberg, Paul; Ismail, Mohd Noor; Poh, Bee Koon

    2016-07-01

    This study aims to validate skinfold (SKF) and bioelectrical impedance analysis (BIA) against dual-energy X-ray absorptiometry (DXA) in determining body fat percentage (BF%) of Malay children aged 7 to 11 years. A total of 160 children had their BF% assessed using SKF and BIA, with DXA as the criterion method. Four SKF equations (SKFBray, SKFJohnston, SKFSlaughter, and SKFGoran) and 4 BIA equations (BIAManufacturer, BIAHoutkooper, BIARush, and BIAKushner) were used to estimate BF%. Mean age, weight, and height were 9.4 ± 1.1years, 30.5 ± 9.9 kg, and 131.3 ± 8.4 cm. All equations significantly underestimated BF% (P < .05). BIA equations had reasonable agreement with DXA and were independent of BF% with BIAManufacturer being the best equation. Although BIA underestimates BF% as compared with DXA, BIA was more suitable to measure BF% in a population that is similar to this study sample than SKF, suggesting a need to develop new SKF equations that are population specific.

  14. Use of DXA-Based Structural Engineering Models of the Proximal Femur to Discriminate Hip Fracture

    PubMed Central

    Yang, Lang; Peel, Nicola; Clowes, Jackie A; McCloskey, Eugene V; Eastell, Richard

    2011-01-01

    Several DXA-based structural engineering models (SEMs) of the proximal femur have been developed to estimate stress caused by sideway falls. Their usefulness in discriminating hip fracture has not yet been established and we therefore evaluated these models. The hip DXA scans of 51 postmenopausal women with hip fracture (30 femoral neck, 17 trochanteric, and 4 unspecified) and 153 age-, height-, and weight-matched controls were reanalyzed using a special version of Hologic’s software that produced a pixel-by-pixel BMD map. For each map, a curved-beam, a curved composite-beam, and a finite element model were generated to calculate stress within the bone when falling sideways. An index of fracture risk (IFR) was defined over the femoral neck, trochanter, and total hip as the stress divided by the yield stress at each pixel and averaged over the regions of interest. Hip structure analysis (HSA) was also performed using Hologic APEX analysis software. Hip BMD and almost all parameters derived from HSA and SEM were discriminators of hip fracture on their own because their ORs were significantly >1. Because of the high correlation of total hip BMD to HSA and SEM-derived parameters, only the bone width discriminated hip fracture independently from total hip BMD. Judged by the area under the receiver operating characteristics curve, the trochanteric IFR derived from the finite element model was significant better than total hip BMD alone and similar to the total hip BMD plus bone width in discriminating all hip fracture and femoral neck fracture. No index was better than total hip BMD for discriminating trochanteric fractures. In conclusion, the finite element model has the potential to replace hip BMD in discriminating hip fractures. PMID:18767924

  15. Use of DXA-based structural engineering models of the proximal femur to discriminate hip fracture.

    PubMed

    Yang, Lang; Peel, Nicola; Clowes, Jackie A; McCloskey, Eugene V; Eastell, Richard

    2009-01-01

    Several DXA-based structural engineering models (SEMs) of the proximal femur have been developed to estimate stress caused by sideway falls. Their usefulness in discriminating hip fracture has not yet been established and we therefore evaluated these models. The hip DXA scans of 51 postmenopausal women with hip fracture (30 femoral neck, 17 trochanteric, and 4 unspecified) and 153 age-, height-, and weight-matched controls were reanalyzed using a special version of Hologic's software that produced a pixel-by-pixel BMD map. For each map, a curved-beam, a curved composite-beam, and a finite element model were generated to calculate stress within the bone when falling sideways. An index of fracture risk (IFR) was defined over the femoral neck, trochanter, and total hip as the stress divided by the yield stress at each pixel and averaged over the regions of interest. Hip structure analysis (HSA) was also performed using Hologic APEX analysis software. Hip BMD and almost all parameters derived from HSA and SEM were discriminators of hip fracture on their own because their ORs were significantly >1. Because of the high correlation of total hip BMD to HSA and SEM-derived parameters, only the bone width discriminated hip fracture independently from total hip BMD. Judged by the area under the receiver operating characteristics curve, the trochanteric IFR derived from the finite element model was significant better than total hip BMD alone and similar to the total hip BMD plus bone width in discriminating all hip fracture and femoral neck fracture. No index was better than total hip BMD for discriminating trochanteric fractures. In conclusion, the finite element model has the potential to replace hip BMD in discriminating hip fractures.

  16. Comparing non contrast computerized tomography criteria versus dual X-ray absorptiometry as predictors of radio-opaque upper urinary tract stone fragmentation after electromagnetic shockwave lithotripsy.

    PubMed

    Hameed, Diaa A; Elgammal, Mohammed A; ElGanainy, Ehab O; Hageb, Adel; Mohammed, Khaled; El-Taher, Ahmed Mohamed; Mostafa, Mostafa Mohamed; Ahmed, Abdelfatah Ibrahim

    2013-11-01

    The objective of this study was to assess the value of dual X-ray absorptiometry (DXA) in comparison to non contrast computed tomography (NCCT) density as possible predictors of upper urinary tract stone disintegration by shock wave lithotripsy (SWL). This study included 100 consecutive patients, with solitary renal stone 0.5-2 cm or upper ureteral stone up to 1 cm. DXA to calculate stone mineral density (SMD) and stone mineral content (SMC) was done. NCCT was performed to measure Hounsfield units (HU). SWL was performed with an electromagnetic lithotripsy, plain X-ray documented disintegration after SWL. Successful treatment was defined as stone free or complete fragmentation after 1 or 2 sessions of SWL. The impact of patients age, sex, body mass index, stone laterality, location, volume, length, mean SMC and SMD, HU and Hounsfield density (HD), skin to stone distance (SSD) and number of shock waves were evaluated by univariate and multivariate analysis. Only 76 patients were available for follow-up. Success of disintegration was observed in 50 out of 76 patients (65.8 %). On multivariate analysis, SMC and number of shock wave were the significant independent factors affecting SWL outcome (p = 0.04 and p = 0.000, respectively). SMC as detected by DXA is a significant predictor of success of stone disintegration by SWL. SMC measured by DXA is more accurate than HU measured by CT. Patients with high stone mineral content (SMC greater than 0.65 g) should be directly offered another treatment option.

  17. DXA estimates of fat in abdominal, trunk and hip regions varies by ethnicity in men

    PubMed Central

    Stults-Kolehmainen, M A; Stanforth, P R; Bartholomew, J B; Lu, T; Abolt, C J; Sinha, R

    2013-01-01

    Objective: The aim of this study was to determine whether the quantity of fat is different across the central (that is, android, trunk) and peripheral (that is, arm, leg and gynoid) regions among young African-American (AA), Asian (AS), Hispanic (HI) and non-Hispanic White (NHW) men. Subjects and Methods: A cohort of 852 men (18–30 years; mean total body fat percent (TBF%)=18.8±7.9, range=3.7–45.4) were assessed for body composition in five body regions via dual-emission X-ray absorptiometry (DXA). Results: HI men (21.8±8.3) had higher TBF% than AA (17.0±10.0), NHW (17.9±7.2) and AS (18.9±8.0) groups (P-values <0.0001). AS had a lower BMI (23.9±3.4) than all other groups, and NHW (24.7±3.2) had a lower BMI than HI (25.7±3.9) and AA (26.5±4.7; P-values<0.0001). A linear mixed model (LMM) revealed a significant ethnicity by region fat% interaction (P<0.0001). HI men had a greater fat% than NHW for every region (adjusted means (%); android: 29.6 vs 23.3; arm: 13.3 vs 10.6; gynoid: 27.2 vs 23.8; leg: 21.2 vs 18.3; trunk: 25.5 vs 20.6) and a greater fat% than AA for every region except the arm. In addition, in the android and trunk regions, HI had a greater fat% than AS, and AS had a higher fat% than AA. Finally, the android fat% for AS was higher than that of NHW. When comparing the region fat% within ethnicities, the android region was greater than the gynoid region for AS and HI, but did not differ for AA and NHW, and the arm region had the least fat% in all ethnicities. Conclusions: Fat deposition and body fat patterning varies by ethnicity. PMID:23507968

  18. Comparison of single- and dual-photon absorptiometry in postmenopausal bone mineral loss

    SciTech Connect

    Nilas, L.; Borg, J.; Gotfredsen, A.; Christiansen, C.

    1985-11-01

    The authors describe a single photon absorptiometric (SPA) technique, which enables differential estimation of the rates of loss from trabecular and cortical bone. Ten scans are obtained in the forearm: six in an area with about 7% trabecular bone and four scans in the adjacent distal area with a trabecular bone content of 25%. By comparing bone masses of these two sites in 19 postmenopausal and 53 premenopausal women, the postmenopausal trabecular bone loss was estimated to be approximately seven times greater than cortical loss within the first years of cessation of regular vaginal bleeding. On a group basis the bone loss at the distal forearm scan site (by SPA) corresponded closely to the spinal bone loss (by dual-photon absorptiometry). The reproducibility of the two scan sites in the forearm was 1-1.5% (CV%), which makes the method suitable for longitudinal studies. Corrections for variations in fatty tissue covering can be made without deterioration of the reproducibility.

  19. Structural trends in the aging femoral neck and proximal shaft: analysis of the Third National Health and Nutrition Examination Survey dual-energy X-ray absorptiometry data.

    PubMed

    Beck, T J; Looker, A C; Ruff, C B; Sievanen, H; Wahner, H W

    2000-12-01

    Hip scans of U.S. adults aged 20-99 years acquired in the Third National Health and Nutrition Examination Survey (NHANES III) using dual-energy X-ray absorptiometry (DXA) were analyzed with a structural analysis program. The program analyzes narrow (3 mm wide) regions at specific locations across the proximal femur to measure bone mineral density (BMD) as well as cross-sectional areas (CSAs), cross-sectional moments of inertia (CSMI), section moduli, subperiosteal widths, and estimated mean cortical thickness. Measurements are reported here on a non-Hispanic white subgroup of 2,719 men and 2,904 women for a cortical region across the proximal shaft 2 cm distal to the lesser trochanter and a mixed cortical/trabecular region across the narrowest point of the femoral neck. Apparent age trends in BMD and section modulus were studied for both regions by sex after correction for body weight. The BMD decline with age in the narrow neck was similar to that seen in the Hologic neck region; BMD in the shaft also declined, although at a slower rate. A different pattern was seen for section modulus; furthermore, this pattern depended on sex. Specifically, the section modulus at both the narrow neck and the shaft regions remains nearly constant until the fifth decade in females and then declined at a slower rate than BMD. In males, the narrow neck section modulus declined modestly until the fifth decade and then remained nearly constant whereas the shaft section modulus was static until the fifth decade and then increased steadily. The apparent mechanism for the discord between BMD and section modulus is a linear expansion in subperiosteal diameter in both sexes and in both regions, which tends to mechanically offset net loss of medullary bone mass. These results suggest that aging loss of bone mass in the hip does not necessarily mean reduced mechanical strength. Femoral neck section moduli in the elderly are on the average within 14% of young values in females and within 6

  20. Associations Between Sedentary Time, Physical Activity, and Dual-Energy X-ray Absorptiometry Measures of Total Body, Android, and Gynoid Fat Mass in Children.

    PubMed

    McCormack, Lacey; Meendering, Jessica; Specker, Bonny; Binkley, Teresa

    2016-01-01

    Negative health outcomes are associated with excess body fat, low levels of physical activity (PA), and high sedentary time (ST). Relationships between PA, ST, and body fat distribution, including android and gynoid fat, assessed using dual-energy X-ray absorptiometry (DXA) have not been measured in children. The purpose of this study was to test associations between levels of activity and body composition in children and to evaluate if levels of activity predict body composition by DXA and by body mass index percentile in a similar manner. PA, ST, and body composition from 87 children (8.8-11.8 yr, grades 3-5, 44 boys) were used to test the association among study variables. Accelerometers measured PA and ST. Body composition measured by DXA included bone mineral content (BMC) and fat and lean mass of the total body (TB, less head), android, and gynoid regions. ST (range: 409-685 min/wk) was positively associated with TB percent fat (0.03, 95% confidence interval [CI]: 0.00-0.05) and android fat mass (1.5 g, 95% CI: 0.4-3.0), and inversely associated with the lean mass of the TB (-10.7 g, 95% CI: -20.8 to -0.63) and gynoid regions (-2.2 g, 95% CI: -4.3 to -0.2), and with BMC (-0.43 g, 95% CI: 0.77-0.09). Moderate-to-vigorous PA was associated with lower TB (-53 g, 95% CI: -87 to -18), android (-5 g, 95% CI: -8 to -2]), and gynoid fat (-6 g, 95% CI: -11 to -0.5). Vigorous activity results were similar. Light PA was associated with increased TB (17.1 g, 95% CI: 3.0-31.3) and gynoid lean mass (3.9 g, 95% CI: 1.0-6.8) and BMC (0.59 g, 95% CI: 0.10-1.07). In boys, there were significant associations between activity and DXA percent body fat measures that were not found with the body mass index percentile. Objective measures of PA were inversely associated with TB, android, and gynoid fat, whereas ST was directly associated with TB percent fat and, in particular, android fat. Activity levels predict body composition measures by DXA and, in

  1. Usefulness of calcaneal quantitative ultrasound stiffness for the evaluation of bone health in HIV-1-infected subjects: comparison with dual X-ray absorptiometry

    PubMed Central

    Fantauzzi, Alessandra; Floridia, Marco; Ceci, Fabrizio; Cacciatore, Francesco; Vullo, Vincenzo; Mezzaroma, Ivano

    2016-01-01

    Objectives With the development of effective treatments and the resulting increase in life expectancy, bone mineral density (BMD) alteration has emerged as an important comorbidity in human immunodeficiency virus type-1 (HIV-1)-infected individuals. The potential contributors to the pathogenesis of osteopenia/osteoporosis include a higher prevalence of risk factors, combined antiretroviral therapy (cART)-exposure, HIV-1 itself and chronic immune activation/inflammation. Dual-energy X-ray absorptiometry (DXA) is the “gold standard” technique for assessing bone status in HIV-1 population. Methods We conducted a cross-sectional study to investigate bone mineral status in a group of 158 HIV-1-infected subjects. The primary endpoint was the feasibility of calcaneal quantitative ultrasound (QUS) as a screening tool for BMD. All subjects were receiving stable cART and were virologically suppressed (HIV-RNA <37 copies/mL) from at least 12 months. Calcaneal QUS parameters were analyzed to obtain information on bone mass and microarchitecture. The results were compared with those obtained by DXA. Results No correlations were found between DXA/QUS parameters and demographic or HIV-1-specific characteristics, also including cART strategies. In the univariate analyses BMD, QUS indexes, and Fracture Risk Assessment Tool scores conversely showed significant associations with one or more demographic or HIV-1-related variables. Moreover, a significant relationship between calcaneal quantitative ultrasound index/stiffness and femoral/lumbar BMD values from DXA was described. The multivariate analysis showed an independent association between calcaneal quantitative ultrasound index/stiffness and body mass index, higher CD4+ T-cell numbers and low 25-OH D2/D3 vitamin D levels <10 ng/mL (P-values: 0.004, 0.016, and 0.015, respectively). Conclusion As an alternative and/or integrative examination to DXA, calcaneal QUS could be proposed as a useful screening in HIV-1-infected

  2. Dual-photon Gd-153 absorptiometry of bone

    SciTech Connect

    Wahner, H.W.; Dunn, W.L.; Mazess, R.B.; Towsley, M.; Lindsay, R.; Markhard, L.; Dempster, D.

    1985-07-01

    Dual-photon absorptiometry with gadolinium 153 was used to measure the mineral content of lumbar vertebrae in cadavers, excised vertebrae with marrow, and dry, marrow-free vertebrae. The error introduced by the surrounding soft tissue of cadavers was 3%, and the error in determining mineral mass or density in excised vertebrae was about 5%. The correlation coefficient between the results of Gd-153 and corrected iodine 125 (single-photon) absorptiometry on 24 femoral necks was 0.99, and the predictive error was 3.7%. Dual-photon absorptiometry accurately indicates bone mass and bone density and is only slightly affected by either surrounding tissue or fat changes in bone marrow.

  3. The relationship between fractures and DXA measures of BMD in the distal femur of children and adolescents with cerebral palsy or muscular dystrophy.

    PubMed

    Henderson, Richard C; Berglund, Lisa M; May, Ryan; Zemel, Babette S; Grossberg, Richard I; Johnson, Julie; Plotkin, Horacio; Stevenson, Richard D; Szalay, Elizabeth; Wong, Brenda; Kecskemethy, Heidi H; Harcke, H Theodore

    2010-03-01

    Children with limited or no ability to ambulate frequently sustain fragility fractures. Joint contractures, scoliosis, hip dysplasia, and metallic implants often prevent reliable measures of bone mineral density (BMD) in the proximal femur and lumbar spine, where BMD is commonly measured. Further, the relevance of lumbar spine BMD to fracture risk in this population is questionable. In an effort to obtain bone density measures that are both technically feasible and clinically relevant, a technique was developed involving dual-energy X-ray absorptiometry (DXA) measures of the distal femur projected in the lateral plane. The purpose of this study is to test the hypothesis that these new measures of BMD correlate with fractures in children with limited or no ability to ambulate. The relationship between distal femur BMD Z-scores and fracture history was assessed in a cross-sectional study of 619 children aged 6 to 18 years with muscular dystrophy or moderate to severe cerebral palsy compiled from eight centers. There was a strong correlation between fracture history and BMD Z-scores in the distal femur; 35% to 42% of those with BMD Z-scores less than -5 had fractured compared with 13% to 15% of those with BMD Z-scores greater than -1. Risk ratios were 1.06 to 1.15 (95% confidence interval 1.04-1.22), meaning a 6% to 15% increased risk of fracture with each 1.0 decrease in BMD Z-score. In clinical practice, DXA measure of BMD in the distal femur is the technique of choice for the assessment of children with impaired mobility.

  4. Correlation between the values of bone measurements using DXA, QCT and USD methods and the bone strength in calcanei in vitro.

    PubMed

    Imamoto, K; Hamanaka, Y; Yamamoto, I; Niiho, C

    1998-10-01

    In this study we used the calcanei from 32 female and 29 male cadavers, ages 58 to 100. The bone mineral density (BMD) and average bone density (ABD) were measured using dual energy X-ray absorptiometry (DXA) and quantitative computed tomography (QCT) respectively, while speed of sound (SOS), broadband ultrasound attenuation (BUA) and stiffness index (SI) were measured using ultrasound densitometry (USD). Thereafter, the bone strength was measured using a compressor to cause bone fracture, and evaluated in comparison with the values of the three measurement methods. The scatter diagrams of the values of the three different methods versus age displayed a negative linear regression in both sexes. Values for BMD and ABD were generally about 20% higher in males than in females, while SOS, BUA and SI were a few percents higher in males than in females. A significantly high correlation existed between BMD and ABD (r = 0.95), and a moderate correlation between BMD and either SOS, BUA or SI (r = 0.65; r = 0.39; r = 0.57, respectively). Thus, among the values measured using USD, SOS most closely corresponded to BMD of the calcanei. The bone strength of the calcanei indicated a moderate correlation with BMD, ABD and SOS (r = 0.38, P < 0.01; r = 0.43, P < 0.001; r = 0.45, P < 0.001, respectively). However, 42 calcanei fractured under pressures of less than 40 kgf, although the other 19 calcanei endured pressure of 40 kgf or more. Two calcanei with high BMD over 0.7 g/cm2 by DXA were very fragile, whereas a few with low BMD less than 0.4 g/cm2 were not very fragile. Similarly, high SOS, BUA and SI values by USD did not always correspond to high bone strength. Thus, some discrepancies among the bone strength and measurement values remained to be solved in the future.

  5. Dual-Energy X-Ray Absorptiometry, Skinfold Thickness, and Waist Circumference for Assessing Body Composition in Ambulant and Non-Ambulant Wheelchair Games Players.

    PubMed

    Willems, Annika; Paulson, Thomas A W; Keil, Mhairi; Brooke-Wavell, Katherine; Goosey-Tolfrey, Victoria L

    2015-01-01

    Field-based assessments provide a cost-effective and accessible alternative to dual-energy X-ray absorptiometry (DXA) for practitioners determining body composition in athletic populations. It remains unclear how the range of physical impairments classifiable in wheelchair sports may affect the utility of field-based body composition techniques. The present study assessed body composition using DXA in 14 wheelchair games players who were either wheelchair dependent (non-walkers; n = 7) or relied on a wheelchair for sports participation only (walkers; n = 7). Anthropometric measurements were used to predict body fat percentage with existing regression equations established for able-bodied persons by Sloan and Weir, Durnin and Womersley, Lean et al, Gallagher et al, and Pongchaiyakul et al. In addition, linear regression analysis was performed to calculate the association between body fat percentage and BMI, waist circumference, sum of 6 skinfold thickness and sum of 8 skinfold thickness. Results showed that non-walkers had significantly lower total lean tissue mass (46.2 ± 6.6 kg vs. 59.4 ± 8.2 kg, P = 0.006) and total body mass (65.8 ± 4.2 kg vs. 79.4 ± 14.9 kg; P = 0.05) than walkers. Body fat percentage calculated from most existing regression equations was significantly lower than that from DXA, by 2 to 9% in walkers and 8 to 14% in non-walkers. Of the anthropometric measurements, the sum of 8 skinfold thickness had the lowest standard error of estimation in predicting body fat content. In conclusion, existing anthropometric equations developed in able-bodied populations substantially underestimated body fat content in wheelchair athletes, particularly non-walkers. Impairment specific equations may be needed in wheelchair athletes.

  6. Body composition analysis of inter-county Gaelic athletic association players measured by dual energy X-ray absorptiometry.

    PubMed

    Davies, Robert W; Toomey, Clodagh; McCormack, William; Hughes, Katie; Cremona, Alexandra; Jakeman, Philip

    2016-01-01

    Gaelic Football and Hurling are two sporting codes within the Gaelic Athletic Association. The purpose of this study was to report the body composition phenotype of inter-county Gaelic athletic association players, comparing groups by code and field position. 190 senior, male, outfield inter-county players (144 hurlers and 46 Gaelic footballers) were recruited. Stature and body mass was measured, estimates of three components of body composition, i.e., lean mass, fat mass and bone mineral content was obtained by dual energy X-ray absorptiometry (DXA), and normative data for Gaelic athletic association athletes by code and position was compared. Other than in the midfield, there was limited difference in body composition between codes or playing position. Stature-corrected indices nullified any existing group differences between midfielders for both codes. Further comparisons with a non-athletic control group (n = 431) showed no difference for body mass index (BMI); however, the athletic group has a lower fat mass index, with a greater lean mass in accounting for the matched BMI between groups. In addition to providing previously unknown normative data for the Gaelic athletic association athlete, a proportional and independent tissue evaluation of body composition is given.

  7. Predicting visceral adipose tissue by MRI using DXA and anthropometry in adolescents and young adults

    PubMed Central

    Laddu, Deepika R.; Lee, Vinson R.; Blew, Robert M.; Sato, Tetsuya; Lohman, Timothy G.; Going, Scott B.

    2015-01-01

    Objective Accumulation of intra-abdominal (visceral) adipose tissue, independent of total adiposity, is associated with development of metabolic abnormalities such as insulin resistance and type-2 diabetes in children and adults. The objective of this study was to develop prediction equations for estimating visceral adiposity (VAT) measured by magnetic resonance imaging (MRI) using anthropometric variables and measures of abdominal fat mass from DXA in adolescents and young adults. Methods Cross-sectional data was collected from a multiethnic population of seventy males and females, aged 12–25 years, with BMI ranging from 14.5–38.1 kg/m2. Android (AFM; android region as defined by manufacturers instruction) and lumbar L1-L4 regional fat masses were assessed using DXA (GE Lunar Prodigy; GE Lunar Corp, Madison, WI, USA). Criterion measures of intra-abdominal visceral fat were obtained using single-slice MRI (General Electric Signa Model 5x 1.5T) and VAT area was analyzed at the level OF L4–L5. Image analysis was carried out using ZedView 3.1. Results DXA measures of AFM (r=0.76) and L1-L4 (r=0.71) were significantly (P<0.0001) correlated with MRI-measured VAT. DXA AFM, together with gender and weight, explained 62% of the variance in VAT (SEE=10.06 cm2). DXA L1-L4 fat mass with gender explained 54% of the variance in VAT (SEE=11.08 cm2). Addition of the significant interaction, gender × DXA fat mass, improved prediction of VAT from AFM (Radj2=0.61, SEE=10.10cm2) and L1-L4 (Radj2=0.59, SEE=10.39cm2). Conclusion These results demonstrate that VAT is accurately estimated from regional fat masses measured by DXA in adolescents and young adults. PMID:26097436

  8. Non-invasive methods for the determination of body and carcass composition in livestock: dual-energy X-ray absorptiometry, computed tomography, magnetic resonance imaging and ultrasound: invited review.

    PubMed

    Scholz, A M; Bünger, L; Kongsro, J; Baulain, U; Mitchell, A D

    2015-07-01

    The ability to accurately measure body or carcass composition is important for performance testing, grading and finally selection or payment of meat-producing animals. Advances especially in non-invasive techniques are mainly based on the development of electronic and computer-driven methods in order to provide objective phenotypic data. The preference for a specific technique depends on the target animal species or carcass, combined with technical and practical aspects such as accuracy, reliability, cost, portability, speed, ease of use, safety and for in vivo measurements the need for fixation or sedation. The techniques rely on specific device-driven signals, which interact with tissues in the body or carcass at the atomic or molecular level, resulting in secondary or attenuated signals detected by the instruments and analyzed quantitatively. The electromagnetic signal produced by the instrument may originate from mechanical energy such as sound waves (ultrasound - US), 'photon' radiation (X-ray-computed tomography - CT, dual-energy X-ray absorptiometry - DXA) or radio frequency waves (magnetic resonance imaging - MRI). The signals detected by the corresponding instruments are processed to measure, for example, tissue depths, areas, volumes or distributions of fat, muscle (water, protein) and partly bone or bone mineral. Among the above techniques, CT is the most accurate one followed by MRI and DXA, whereas US can be used for all sizes of farm animal species even under field conditions. CT, MRI and US can provide volume data, whereas only DXA delivers immediate whole-body composition results without (2D) image manipulation. A combination of simple US and more expensive CT, MRI or DXA might be applied for farm animal selection programs in a stepwise approach. PMID:25743562

  9. Non-invasive methods for the determination of body and carcass composition in livestock: dual-energy X-ray absorptiometry, computed tomography, magnetic resonance imaging and ultrasound: invited review.

    PubMed

    Scholz, A M; Bünger, L; Kongsro, J; Baulain, U; Mitchell, A D

    2015-07-01

    The ability to accurately measure body or carcass composition is important for performance testing, grading and finally selection or payment of meat-producing animals. Advances especially in non-invasive techniques are mainly based on the development of electronic and computer-driven methods in order to provide objective phenotypic data. The preference for a specific technique depends on the target animal species or carcass, combined with technical and practical aspects such as accuracy, reliability, cost, portability, speed, ease of use, safety and for in vivo measurements the need for fixation or sedation. The techniques rely on specific device-driven signals, which interact with tissues in the body or carcass at the atomic or molecular level, resulting in secondary or attenuated signals detected by the instruments and analyzed quantitatively. The electromagnetic signal produced by the instrument may originate from mechanical energy such as sound waves (ultrasound - US), 'photon' radiation (X-ray-computed tomography - CT, dual-energy X-ray absorptiometry - DXA) or radio frequency waves (magnetic resonance imaging - MRI). The signals detected by the corresponding instruments are processed to measure, for example, tissue depths, areas, volumes or distributions of fat, muscle (water, protein) and partly bone or bone mineral. Among the above techniques, CT is the most accurate one followed by MRI and DXA, whereas US can be used for all sizes of farm animal species even under field conditions. CT, MRI and US can provide volume data, whereas only DXA delivers immediate whole-body composition results without (2D) image manipulation. A combination of simple US and more expensive CT, MRI or DXA might be applied for farm animal selection programs in a stepwise approach.

  10. REVIEW: Photon absorptiometry, bone densitometry and the challenge of osteoporosis

    NASA Astrophysics Data System (ADS)

    Webber, Colin E.

    2006-07-01

    During the lifetime of Physics in Medicine and Biology, osteoporosis has been recognized as the cause of a major health burden for societies, particularly within developed countries. The health detriment is associated with the consequences of bone fractures and the subsequent increases in morbidity and mortality. Much of the credit for the current availability of means for identifying groups of subjects at risk of fracture and the provision of means for the effective treatment of excessive bone loss can be attributed to the technique of dual photon absorptiometry. In this review, the history of the development of techniques based on the interactions of x- and γ-rays with bone is considered and the ultimate dominance of x-ray based absorptiometry is described. The advantages and disadvantages of current absorptiometric techniques are presented and the likely future path for bone measurement is outlined.

  11. Predicting Bone Mechanical Properties of Cancellous Bone from DXA, MRI, and Fractal Dimensional Measurements

    NASA Technical Reports Server (NTRS)

    Harrigan, Timothy P.; Ambrose, Catherine G.; Hogan, Harry A.; Shackleford, Linda; Webster, Laurie; LeBlanc, Adrian; Lin, Chen; Evans, Harlan

    1997-01-01

    This project was aimed at making predictions of bone mechanical properties from non-invasive DXA and MRI measurements. Given the bone mechanical properties, stress calculations can be made to compare normal bone stresses to the stresses developed in exercise countermeasures against bone loss during space flight. These calculations in turn will be used to assess whether mechanical factors can explain bone loss in space. In this study we assessed the use of T2(sup *) MRI imaging, DXA, and fractal dimensional analysis to predict strength and stiffness in cancellous bone.

  12. Dual X-Ray Absorptiometry Whole Body Composition of Bone Tissue in Rheumatoid Arthritis – a Cross-Sectional Study

    PubMed Central

    POPESCU, Claudiu; BOJINCA, Violeta; OPRIS, Daniela; IONESCU, Ruxandra

    2015-01-01

    Objectives: Previous studies of bone tissue in rheumatoid arthritis (RA) using dual X-ray absorptiometry (DXA) concentrated on regions of interest that were used to diagnose osteoporosis. This study aimed to compare the whole body bone tissue (wbBT) of RA patients with healthy subjects and to identify the RA variables which significantly predict wbBT. Methods: The study was cross-sectionally designed to include postmenopausal RA patients and age-matched healthy female controls. All 107 RA patients and all 104 controls underwent clinical examination, laboratory tests and whole body DXA composition, which recorded total and regional bone indices. Non-parametric standard statistical test and regression models after data normalization were used to assess correlations, associations and differences. Results: Compared to controls, RA patients had significantly lower whole body and regional bone mass (14.9 kg compared to 15.5 kg; p = 0.031). Disease duration (r = -0.402 ; p < 0.001), C-reactive protein (r = -0.279; p = 0.015) and inflammation (2.5% wbBT compared to 2.9%; p = 0.043), radiographic damage (14.3 kg compared to 16.2 kg; p < 0.001), disease activity scores (r = -0.275 ; p = 0.018 for HAQ) are significantly correlated/associated with lower wbBT. Clinical structural damage is associated with lower wbBT and it can significantly predict them (R2 = 0.014; p = 0.001), while glucocorticoid treatment, even in low doses, was associated with lower wbBT percent (2.6% compared to 2.8%; p = 0.045). Treatment with biologics was associated with a lower rate of whole body osteoporosis (0% compared to 22.2%; p = 0.013). Conclusions: The main associated factors with the generalized bone loss in female RA patients are disease duration and disease activity. Clinical structural damage is the most powerful predictor of the whole body bone loss. These results suggest a general disturbance of skeletal bone metabolism in RA and could explain a greater risk of fragility fractures of non

  13. The Performance of Five Bioelectrical Impedance Analysis Prediction Equations against Dual X-ray Absorptiometry in Estimating Appendicular Skeletal Muscle Mass in an Adult Australian Population

    PubMed Central

    Yu, Solomon C. Y.; Powell, Alice; Khow, Kareeann S. F.; Visvanathan, Renuka

    2016-01-01

    Appendicular skeletal muscle mass (ASM) is a diagnostic criterion for sarcopenia. Bioelectrical impedance analysis (BIA) offers a bedside approach to measure ASM but the performance of BIA prediction equations (PE) varies with ethnicities and body composition. We aim to validate the performance of five PEs in estimating ASM against estimation by dual-energy X-ray absorptiometry (DXA). We recruited 195 healthy adult Australians and ASM was measured using single-frequency BIA. Bland-Altman analysis was used to assess the predictive accuracy of ASM as determined by BIA against DXA. Precision (root mean square error (RMSE)) and bias (mean error (ME)) were calculated according to the method of Sheiner and Beal. Four PEs (except that by Kim) showed ASM values that correlated strongly with ASMDXA (r ranging from 0.96 to 0.97, p < 0.001). The Sergi equation performed the best with the lowest ME of −1.09 kg (CI: −0.84–−1.34, p < 0.001) and the RMSE was 2.09 kg (CI: 1.72–2.47). In men, the Kyle equation performed better with the lowest ME (−0.32 kg (CI: −0.66–0.02) and RMSE (1.54 kg (CI: 1.14–1.93)). The Sergi equation is applicable in adult Australians (Caucasian) whereas the Kyle equation can be considered in males. The need remains to validate PEs in other ethnicities and to develop equations suitable for multi-frequency BIA. PMID:27043617

  14. Comparative study of quantitative ultrasonography and dual-energy X-ray absorptiometry for evaluating renal osteodystrophy in children with chronic kidney disease.

    PubMed

    Christoforidis, Athanasios; Printza, Nikoleta; Gkogka, Chrysa; Siomou, Ekaterini; Challa, Anna; Kazantzidou, Eirini; Kollios, Konstantinos; Papachristou, Fotis

    2011-05-01

    Our aim was to assess bone parameters in children with chronic kidney disease (CKD) with both dual-energy X-ray absorptiometry (DXA) and quantitative ultrasonography (QUS) and additionally with biochemical markers of bone turnover. Twenty children (12 boys and 8 girls) with CKD and a mean decimal age of 9.47 ± 4.44 years were included in the study where anthropometric parameters (height and weight), pubertal status, bone mineral density (BMD) at lumbar spine, speed of sound (SOS) measured by QUS at radius and at tibia, and biochemical markers of bone metabolism were measured. Six patients (30%) had tibial SOS Z score <-1, and 52.7% had radial SOS Z score <-1, whereas only 16.67% had BMD Z score <-1. Patients had significantly increased levels of serum intact parathormone (p < 0.001), serum bone alkaline phosphatase (BAP) (p < 0.001) and serum N-terminal-mid fragment (aminoacids 1-43) of osteocalcin (p < 0.001) compared to controls, whereas serum osteoprotegerin was significantly decreased in patients compared to controls (p = 0.001). SOS was significantly correlated to BAP (r = -0.586, p = 0.013 and r = -0.709, p = 0.001, respectively, for radius and tibia). In conclusion no association between DXA and QUS measurements was documented in our study, whereas QUS was better correlated to biochemical indices of ROD.

  15. Cross-mode bioelectrical impedance analysis in a standing position for estimating fat-free mass validated against dual-energy x-ray absorptiometry.

    PubMed

    Huang, Ai-Chun; Chen, Yu-Yawn; Chuang, Chih-Lin; Chiang, Li-Ming; Lu, Hsueh-Kuan; Lin, Hung-Chi; Chen, Kuen-Tsann; Hsiao, An-Chi; Hsieh, Kuen-Chang

    2015-11-01

    Bioelectrical impedance analysis (BIA) is commonly used to assess body composition. Cross-mode (left hand to right foot, Z(CR)) BIA presumably uses the longest current path in the human body, which may generate better results when estimating fat-free mass (FFM). We compared the cross-mode with the hand-to-foot mode (right hand to right foot, Z(HF)) using dual-energy x-ray absorptiometry (DXA) as the reference. We hypothesized that when comparing anthropometric parameters using stepwise regression analysis, the impedance value from the cross-mode analysis would have better prediction accuracy than that from the hand-to-foot mode analysis. We studied 264 men and 232 women (mean ages, 32.19 ± 14.95 and 34.51 ± 14.96 years, respectively; mean body mass indexes, 24.54 ± 3.74 and 23.44 ± 4.61 kg/m2, respectively). The DXA-measured FFMs in men and women were 58.85 ± 8.15 and 40.48 ± 5.64 kg, respectively. Multiple stepwise linear regression analyses were performed to construct sex-specific FFM equations. The correlations of FFM measured by DXA vs. FFM from hand-to-foot mode and estimated FFM by cross-mode were 0.85 and 0.86 in women, with standard errors of estimate of 2.96 and 2.92 kg, respectively. In men, they were 0.91 and 0.91, with standard errors of the estimates of 3.34 and 3.48 kg, respectively. Bland-Altman plots showed limits of agreement of -6.78 to 6.78 kg for FFM from hand-to-foot mode and -7.06 to 7.06 kg for estimated FFM by cross-mode for men, and -5.91 to 5.91 and -5.84 to 5.84 kg, respectively, for women. Paired t tests showed no significant differences between the 2 modes (P > .05). Hence, cross-mode BIA appears to represent a reasonable and practical application for assessing FFM in Chinese populations.

  16. [OsteoLaus: prediction of osteoporotic fractures by clinical risk factors and DXA, IVA and TBS].

    PubMed

    Lamy, O; Metzger, M; Krieg, M-A; Aubry-Rozier, B; Stoll, D; Hans, D

    2011-11-01

    OsteoLaus is a cohort of 1400 women 50 to 80 years living in Lausanne, Switzerland. Clinical risk factors for osteoporosis, bone ultrasound of the heel, lumbar spine and hip bone mineral density (BMD), assessment of vertebral fracture by DXA, and microarchitecture evaluation by TBS (Trabecular Bone Score) will be recorded. TBS is a new parameter obtained after a re-analysis of a DXA exam. TBS is correlated with parameters of microarchitecture. His reproducibility is good. TBS give an added diagnostic value to BMD, and predict osteoporotic fracture (partially) independently to BMD. The position of TBS in clinical routine in complement to BMD and clinical risk factors will be evaluated in the OsteoLaus cohort.

  17. Comparison of Speed of Sound Measures Assessed by Multisite Quantitative Ultrasound to Bone Mineral Density Measures Assessed by Dual-Energy X-Ray Absorptiometry in a Large Canadian Cohort: the Canadian Multicentre Osteoporosis Study (CaMos).

    PubMed

    Olszynski, Wojciech P; Adachi, Jonathon D; Hanley, David A; Davison, Kenneth S; Brown, Jacques P

    2016-01-01

    Dual-energy X-ray absorptiometry (DXA) is an important tool for the estimate of fracture risk through the measurement of bone mineral density (BMD). Similarly, multisite quantitate ultrasound can prospectively predict future fracture through the measurement of speed of sound (SOS). This investigation compared BMD (at the femoral neck, total hip, and lumbar spine) and SOS measures (at the distal radius, tibia, and phalanx sites) in a large sample of randomly-selected and community-based individuals from the Canadian Multicentre Osteoporosis Study. Furthermore, mass, height, and age were also compared with both measures. There were 4123 patients included with an age range of 30-96.8 yr. Pearson product moment correlations between BMD and SOS measures were low (0.21-0.29; all p<0.001), irrespective of site. Mass was moderately correlated with BMD measures (0.40-0.58; p<0.001), but lowly correlated with SOS measures (0.03-0.13; p<0.05). BMD and SOS were negatively correlated to age (-0.17 to -0.44; p<0.001). When regression analyses were performed to predict SOS measures at the 3 sites, the models predicted 20%-23% of the variance, leaving 77%-80% unaccounted for. The SOS measures in this study were found to be largely independent from BMD measures. In areas with no or limited access to DXA, the multisite quantitative ultrasound may act as a valuable tool to assess fracture risk. In locales with liberal access to DXA, the addition of SOS to BMD and other clinical risk factors may improve the identification of those patients at high risk for future fracture.

  18. Comparison of Standing Posture Bioelectrical Impedance Analysis with DXA for Body Composition in a Large, Healthy Chinese Population

    PubMed Central

    Chen, Kuen-Tsann; Chen, Yu-Yawn; Wang, Chia-Wei; Chuang, Chih-Lin; Chiang, Li-Ming; Lai, Chung-Liang; Lu, Hsueh-Kuan; Dwyer, Gregory B.; Chao, Shu-Ping; Shih, Ming-Kuei; Hsieh, Kuen-Chang

    2016-01-01

    Bioelectrical impedance analysis (BIA) is a common method for assessing body composition in research and clinical trials. BIA is convenient but when compared with other reference methods, the results have been inconclusive. The level of obesity degree in subjects is considered to be an important factor affecting the accuracy of the measurements. A total of 711 participants were recruited in Taiwan and were sub-grouped by gender and levels of adiposity. Regression analysis and Bland-Altman analysis were used to evaluate the agreement of the measured body fat percentage (BF%) between BIA and DXA. The BF% measured by the DXA and BIA methods (Tanita BC-418) were expressed as BF%DXA and BF%BIA8, respectively. A one-way ANOVA was used to test the differences in BF% measurements by gender and levels of adiposity. The estimated BF%BIA8 and BF%DXA in the all subjects, male and female groups were all highly correlated (r = 0.934, 0.901, 0.916, all P< 0.001). The average estimated BF%BIA8 (22.54 ± 9.48%) was significantly lower than the average BF%DXA (26.26 ± 11.18%). The BF%BIA8 was overestimated in the male subgroup (BF%DXA< 15%), compared to BF%DXA by 0.45%, respectively. In the other subgroups, the BF%BIA8 values were all underestimated. Standing BIA estimating body fat percentage in Chinese participants have a high correlation, but underestimated on normal and high obesity degree in both male and female subjects. PMID:27467065

  19. Comparison of Standing Posture Bioelectrical Impedance Analysis with DXA for Body Composition in a Large, Healthy Chinese Population.

    PubMed

    Chen, Kuen-Tsann; Chen, Yu-Yawn; Wang, Chia-Wei; Chuang, Chih-Lin; Chiang, Li-Ming; Lai, Chung-Liang; Lu, Hsueh-Kuan; Dwyer, Gregory B; Chao, Shu-Ping; Shih, Ming-Kuei; Hsieh, Kuen-Chang

    2016-01-01

    Bioelectrical impedance analysis (BIA) is a common method for assessing body composition in research and clinical trials. BIA is convenient but when compared with other reference methods, the results have been inconclusive. The level of obesity degree in subjects is considered to be an important factor affecting the accuracy of the measurements. A total of 711 participants were recruited in Taiwan and were sub-grouped by gender and levels of adiposity. Regression analysis and Bland-Altman analysis were used to evaluate the agreement of the measured body fat percentage (BF%) between BIA and DXA. The BF% measured by the DXA and BIA methods (Tanita BC-418) were expressed as BF%DXA and BF%BIA8, respectively. A one-way ANOVA was used to test the differences in BF% measurements by gender and levels of adiposity. The estimated BF%BIA8 and BF%DXA in the all subjects, male and female groups were all highly correlated (r = 0.934, 0.901, 0.916, all P< 0.001). The average estimated BF%BIA8 (22.54 ± 9.48%) was significantly lower than the average BF%DXA (26.26 ± 11.18%). The BF%BIA8 was overestimated in the male subgroup (BF%DXA< 15%), compared to BF%DXA by 0.45%, respectively. In the other subgroups, the BF%BIA8 values were all underestimated. Standing BIA estimating body fat percentage in Chinese participants have a high correlation, but underestimated on normal and high obesity degree in both male and female subjects. PMID:27467065

  20. Combining 3D optical imaging and dual energy absorptiometry to measure three compositional components.

    PubMed

    Malkov, Serghei; Shepherd, John

    2014-02-17

    We report on the design of the technique combining 3D optical imaging and dual-energy absorptiometry body scanning to estimate local body area compositions of three compartments. Dual-energy attenuation and body shape measures are used together to solve for the three compositional tissue thicknesses: water, lipid, and protein. We designed phantoms with tissue-like properties as our reference standards for calibration purposes. The calibration was created by fitting phantom values using non-linear regression of quadratic and truncated polynomials. Dual-energy measurements were performed on tissue-mimicking phantoms using a bone densitometer unit. The phantoms were made of materials shown to have similar x-ray attenuation properties of the biological compositional compartments. The components for the solid phantom were tested and their high energy/low energy attenuation ratios are in good correspondent to water, lipid, and protein for the densitometer x-ray region. The three-dimensional body shape was reconstructed from the depth maps generated by Microsoft Kinect for Windows. We used open-source Point Cloud Library and freeware software to produce dense point clouds. Accuracy and precision of compositional and thickness measures were calculated. The error contributions due to two modalities were estimated. The preliminary phantom composition and shape measurements are found to demonstrate the feasibility of the method proposed.

  1. Dual photon absorptiometry using a gadolinium-153 source applied to measure equine bone mineral content

    NASA Astrophysics Data System (ADS)

    Moure, Alessandro; Reichmann, Peter; Remigio Gamba, Humberto

    2003-12-01

    The application of the dual photon absorptiometry (DPA) technique, using gadolinium-153 as the photon source, to evaluate the bone mineral density (BMD) of the third metacarpal bone of horses is presented. The radiation detector was implemented with a NaI(TI) scintillator coupled to a 14 stage photomultiplier. A modular mechanical system allows the position of the prototype to be adjusted in relation to the animal. A moveable carrier makes it possible to scan the third metacarpal with a velocity adjustable between 1 and 12 mm s-1, in steps of 1 mm s-1, for a total distance of 250 mm. The prototype was evaluated with a phantom of the third metacarpal bone made of perspex and aluminium, and in vitro with a transverse slice of the third metacarpal bone of a horse. The tests showed that the prototype has an accuracy and precision of, approximately, 10% and 6%, respectively, for a 6 s acquisition time. Preliminary studies carried out in three foals from birth to one year of age indicated that the prototype is well suited to in vivo and in situ analysis of the BMD of the third metacarpal bones of horses, making it possible to evaluate the changes of BMD levels on a monthly basis. Also, results indicated an exponential behaviour of the BMD curve during the first year of life of the studied horses.

  2. Combining 3D optical imaging and dual energy absorptiometry to measure three compositional components

    PubMed Central

    Malkov, Serghei; Shepherd, John

    2014-01-01

    We report on the design of the technique combining 3D optical imaging and dual-energy absorptiometry body scanning to estimate local body area compositions of three compartments. Dual-energy attenuation and body shape measures are used together to solve for the three compositional tissue thicknesses: water, lipid, and protein. We designed phantoms with tissue-like properties as our reference standards for calibration purposes. The calibration was created by fitting phantom values using non-linear regression of quadratic and truncated polynomials. Dual-energy measurements were performed on tissue-mimicking phantoms using a bone densitometer unit. The phantoms were made of materials shown to have similar x-ray attenuation properties of the biological compositional compartments. The components for the solid phantom were tested and their high energy/low energy attenuation ratios are in good correspondent to water, lipid, and protein for the densitometer x-ray region. The three-dimensional body shape was reconstructed from the depth maps generated by Microsoft Kinect for Windows. We used open-source Point Cloud Library and freeware software to produce dense point clouds. Accuracy and precision of compositional and thickness measures were calculated. The error contributions due to two modalities were estimated. The preliminary phantom composition and shape measurements are found to demonstrate the feasibility of the method proposed. PMID:25083118

  3. Combining 3D optical imaging and dual energy absorptiometry to measure three compositional components

    NASA Astrophysics Data System (ADS)

    Malkov, Serghei; Shepherd, John

    2014-02-01

    We report on the design of the technique combining 3D optical imaging and dual-energy absorptiometry body scanning to estimate local body area compositions of three compartments. Dual-energy attenuation and body shape measures are used together to solve for the three compositional tissue thicknesses: water, lipid, and protein. We designed phantoms with tissue-like properties as our reference standards for calibration purposes. The calibration was created by fitting phantom values using non-linear regression of quadratic and truncated polynomials. Dual-energy measurements were performed on tissue-mimicking phantoms using a bone densitometer unit. The phantoms were made of materials shown to have similar x-ray attenuation properties of the biological compositional compartments. The components for the solid phantom were tested and their high energy/low energy attenuation ratios are in good correspondent to water, lipid, and protein for the densitometer x-ray region. The three-dimensional body shape was reconstructed from the depth maps generated by Microsoft Kinect for Windows. We used open-source Point Cloud Library and freeware software to produce dense point clouds. Accuracy and precision of compositional and thickness measures were calculated. The error contributions due to two modalities were estimated. The preliminary phantom composition and shape measurements are found to demonstrate the feasibility of the method proposed.

  4. Effect of weight loss on bone mineral density determined by ultrasound of phalanges in obese women after Roux-en-y gastric bypass: conflicting results with dual-energy X-ray absorptiometry.

    PubMed

    Lima, Tatiana Pereira; Nicoletti, Carolina Ferreira; Marchini, Julio Sergio; Junior, Wilson Salgado; Nonino, Carla Barbosa

    2014-01-01

    The rapid weight loss that occurs in obese patients submitted to Roux-en-y gastric bypass (RYGB) as well as the changes in dietary pattern and the intestinal malabsorption result in changes in bone mineral density (BMD). The objective of the present study was to assess the changes in BMD after the weight loss induced by RYGB using ultrasound of the phalanges and compare the results with those obtained by dual-energy X-ray absorptiometry (DXA). We conducted a 1-yr prospective longitudinal study on women with grade III obesity submitted to RYGB. Anthropometric (weight, height, body mass index, and abdominal circumference) and body composition measurements by electrical bioimpedance, assessment of food consumption by 24-h recall, biochemical evaluation, and assessment of BMD by ultrasonography of the phalanges and DXA (BMD values are from the 33% radius site) were performed during the preoperative period and 3, 6, and 12 mo after surgery. The mixed-effects linear regression model was used to analyze the effect of postoperative time on the variable of interest, and the kappa coefficient (p < 0.05) was used to compare the concordance of the methods used for BMD evaluation. Twenty-nine patients were included in the study. During the 1-yr follow-up, a reduction of 39 ± 8 kg (71 ± 15% of excess weight) and 29 ± 7 kg of fat mass was observed. Calcium and zinc concentrations were reduced after 12 mo. No difference in caffeine, calcium, or sodium consumption was observed between the preoperative and postoperative periods. Analysis of BMD by ultrasonography of the phalanges 1 yr after surgery showed increased values of amplitude-dependent speed of sound (2064.6 ± 59.4 vs 2154.7 ± 63 m/s; p < 0.001) and ultrasound bone profile index (0.73 ± 0.13 vs 0.76 ± 0.14; p < 0.001). Analysis of BMD by DXA showed a reduction of BMD values (0.6 ± 0.04 vs 0.57 ± 0.05 g/cm³; p < 0.001) in the sixth month and maintenance of the values from the sixth to the 12th month. At the end of

  5. Reproducibility of dual-photon absorptiometry using a clinical phantom

    SciTech Connect

    DaCosta, M.; DeLaney, M.; Goldsmith, S.J.

    1985-05-01

    The use of dual-photon absorptiometry (DPA) bone mineral density (BMD) to monitor bone for diagnosis and monitoring therapy of osteoporosis has been established. The objective of this study is to determine the reproducibility of DPA measurements. A phantom was constructed using a section of human boney pelvis and lumbo-sacral spine. Provisions were made to mimic changes in patient girth. To evaluate the DPA reproducibility within a single day, 12 consecutive studies were performed on the phantom using standard acquisition and processing procedures. The mean BMD +-1 SD in gms/cm/sup 2/ (BMD-bar)of lumbar vertebrae 2-4 was 0.771 +- 0.007 with a 0.97% coefficient of variation (1SD) (CV). This evaluation was repeated 7 times over the next 4 months with the performance of 3 to 6 studies each time, the maximum CV found was 1.93. In order to evaluate the DPA reproducibility with time, phantom studies were performed over a 7 month period which included a 153-Gd source change. The BMD-bar was 0.770 +- 0.017 with a 2.15CV. DPA reproducibility with patient girth changes was evaluated by performing the phantom studies at water depths of 12.5, 17.0 and 20.0cm. Five studies of each were performed using standard acquisition and processing procedures. The BMD-bar was 0.779 +- 0.012 with a 1.151CV. based on these results, BMD measurements by DPA are reproducible within 2%. This reliability is maintained for studies performed over extended period of time and are independent of changes in patient girth.

  6. Disproportionate, age-related bone loss in long bone ends: a structural analysis based on dual-energy X-ray absorptiometry.

    PubMed

    Sievänen, H; Uusi-Rasi, K; Heinonen, A; Oja, P; Vuori, I

    1999-01-01

    The width of long bone diaphyses apparently increase with age, a phenomenon that is suggested to have some positive impact on bone strength. On the other hand, these changes in size that are site-specific may cause a deterioration in the local mechanical integrity of the whole bone. Physical activity and calcium intake are known to be able to modify bone mass and size. It is, however, not known whether these lifestyle habits can modify the postulated disproportionate changes in bone size. To address this question, bone mineral content (BMC)-derived estimates of cross-sectional areas (CSA) of femur and radius in 158 premenopausal (mean age 43, standard deviation 2 years) and 134 postmenopausal (63 (2) years), clinically healthy women with contrasting long-term histories in physical activity and calcium intake were determined from dual-energy X-ray absorptiometry (DXA) data. The DXA-obtained BMC correlated strongly with the actual CSA (r = 0.94) determined with peripheral quantitative computed tomography. The ratios between functionally interrelated CSA data (i.e., (radial shaft CSA/distal radius CSA), (trochanter CSA/femoral neck CSA), (femoral shaft CSA/trochanter CSA) and (femoral shaft CSA/femoral neck CSA)) were considered primary outcome variables. Neither physical activity nor calcium intake separately or interactively were associated with any CSA ratio. Age showed no interaction with physical activity or calcium intake but was independently associated with all CSA ratios, except the ratio of femoral shaft CSA to trochanteric CSA. This study indicated clearly that a preferential reduction in the cross-sectional area occupied by bone mineral occurs disproportionately at the long bone ends as compared with diaphyseal sites, and this apparently inherent, age-associated relative loss seems not to be prevented by physical activity or calcium intake. In particular, given the utmost clinical relevance of the proximal femur region, an observed loss in femoral neck CSA

  7. Sex- and age-related differences in femoral neck cross-sectional structural changes in mainland Chinese men and women measured using dual-energy X-ray absorptiometry.

    PubMed

    Gong, Jian; Tang, Min; Guo, Bin; Shang, JingJie; Tang, Yongjin; Xu, Hao

    2016-02-01

    We investigated age-related changes in estimated bone strength and cross-sectional structure of the femoral neck (FN) in mainland Chinese men and women (according to age and sex) using dual-energy X-ray absorptiometry (DXA). A total of 3855 healthy adults (2713 women, 1142 men; ages 25-91years) were analyzed by FN bone mineral density (BMD) assessment and hip structural/strength analysis (HSA), including cross-sectional moment of inertia (CSMI), cross-sectional area (CSA), section modulus (Z), periosteal diameter (PD), endocortical diameter (ED), and cortical thickness (CT) using DXA. HSA differences between age and sex groups were adjusted for body weight, height and FN BMD. Trends according to age were estimated by linear regression analysis. There was no inverse correlation between HSA parameters and age in young adults. Some HSA parameters (CSMI, CSA, Z, CT) decreased significantly with age, whereas PD and ED increased significantly. Older adults had less estimated bone strength and CT and higher PD and ED (p<0.05) than young adults. Men had greater increases in PD and ED than women across all ages. FN strength decreases with age in both sexes, caused by FN cross-sectional structural deterioration. Indirect comparison of our data with those from other populations showed less age-related FN periosteal apposition in Chinese than Caucasian men, but similar amounts in women. This may partly explain different male/female hip fracture rates among ethnic groups. Chinese men have more structural disadvantages regarding FN geometry during aging than Caucasian men, possibly conferring added susceptibility to hip fracture.

  8. Reference data and percentile curves of body composition measured with dual energy X-ray absorptiometry in healthy Chinese children and adolescents.

    PubMed

    Guo, Bin; Xu, Yi; Gong, Jian; Tang, Yongjin; Shang, Jingjie; Xu, Hao

    2015-09-01

    Measurements of body composition by dual-energy X-ray absorptiometry (DXA) have evident value in evaluating skeletal and muscular status in growing children and adolescents. This study aimed to generate age-related trends for body composition in Chinese children and adolescents, and to establish gender-specific reference percentile curves for the assessment of muscle-bone status. A total of 1541 Chinese children and adolescents aged from 5 to 19 years were recruited from southern China. Bone mineral content (BMC), lean mass (LM) and fat mass (FM) were measured for total body and total body less head (TBLH). After 14 years, total body LM was significantly higher in boys than girls (p < 0.001). However, total body FM was significantly higher in girls than boys in age groups 13-19 years (p < 0.01). Both LM and FM were consistent independent predictors of total body and subcranial bone mass in both sexes, even after adjustment for the well-known predictors of BMC. The results of multiple linear regression identified LM as the stronger predictor of total body and subcranial skeleton BMC while the fat mass contributed less. For all the subjects, significant positive correlations were observed between total body LM, height, total body BMC and subcranial BMC (p < 0.01). Subcranial BMC had a better correlation with LM than total body BMC. We have also presented gender-specific percentile curves for LM-for-height and BMC-for-LM which could be used to evaluate and follow various pediatric disorders with skeletal manifestations in this population. PMID:25319556

  9. High resolution magnetic resonance imaging of the calcaneus: age-related changes in trabecular structure and comparison with dual X-ray absorptiometry measurements

    NASA Technical Reports Server (NTRS)

    Ouyang, X.; Selby, K.; Lang, P.; Engelke, K.; Klifa, C.; Fan, B.; Zucconi, F.; Hottya, G.; Chen, M.; Majumdar, S.; Genant, H. K.

    1997-01-01

    A high-resolution magnetic resonance imaging (MRI) protocol, together with specialized image processing techniques, was applied to the quantitative measurement of age-related changes in calcaneal trabecular structure. The reproducibility of the technique was assessed and the annual rates of change for several trabecular structure parameters were measured. The MR-derived trabecular parameters were compared with calcaneal bone mineral density (BMD), measured by dual X-ray absorptiometry (DXA) in the same subjects. Sagittal MR images were acquired at 1.5 T in 23 healthy women (mean age: 49.3 +/- 16.6 [SD]), using a three-dimensional gradient echo sequence. Image analysis procedures included internal gray-scale calibration, bone and marrow segmentation, and run-length methods. Three trabecular structure parameters, apparent bone volume (ABV/TV), intercept thickness (I.Th), and intercept separation (I.Sp) were calculated from the MR images. The short- and long-term precision errors (mean %CV) of these measured parameters were in the ranges 1-2% and 3-6%, respectively. Linear regression of the trabecular structure parameters vs. age showed significant correlation: ABV/TV (r2 = 33.7%, P < 0.0037), I.Th (r2 = 26.6%, P < 0.0118), I.Sp (r2 = 28.9%, P < 0.0081). These trends with age were also expressed as annual rates of change: ABV/TV (-0.52%/year), I.Th (-0.33%/year), and I.Sp (0.59%/year). Linear regression analysis also showed significant correlation between the MR-derived trabecular structure parameters and calcaneal BMD values. Although a larger group of subjects is needed to better define the age-related changes in trabecular structure parameters and their relation to BMD, these preliminary results demonstrate that high-resolution MRI may potentially be useful for the quantitative assessment of trabecular structure.

  10. Bone quality and bone mass as assessed by quantitative ultrasound and dual energy x ray absorptiometry in women with rheumatoid arthritis: relationship with quadriceps strength

    PubMed Central

    Madsen, O; Sorensen, O; Egsmose, C

    2002-01-01

    Objective: To examine relationships of bone quality as assessed by quantitative ultrasound (QUS) and bone mineral density (BMD, g/cm2) with quadriceps strength (QS) in women with rheumatoid arthritis (RA). Methods: Sixty seven women with RA according to the 1987 American College of Rheumatology (ACR) criteria were examined. Mean (SD) age was 62 (13) years, mean disease duration 15 years. Most were or had been receiving glucocorticoid treatment. Calcaneal bone quality expressed as speed of sound (SOS, m/s), broadband ultrasound attenuation (BUA, dB/MHz), and stiffness was measured by QUS. BMD of the femoral neck, spine, and distal forearm was measured by dual energy x ray absorptiometry (DXA). Maximal voluntary isokinetic quadriceps strength (Nm) was assessed by isokinetic dynamometry. Pain was recorded on a visual analogue scale (VAS), disability was scored by the Stanford Health Assessment Questionnaire (HAQ), and the degree of physical impairment was expressed by the Steinbrocker index (SI). Results: In multiple regression analyses, QS predicted SOS, BUA, and stiffness (rpartial ranging from 0.36 to 0.45, p<0.005) and femoral neck BMD (rpartial=0.30, p<0.05) independently of age, height, weight, disease duration, HAQ, VAS, SI, and cumulative steroid dose. BMD of the spine and distal forearm was not associated with QS. After adjustment for covariates, women with subnormal BMD of the femoral neck (T score <-1), had a 20% lower QS than those with normal BMD (p<0.0001). Conclusions: Calcaneal bone quality and femoral neck BMD were associated with QS in women with RA. This finding indicates that physical activity including muscle strengthening exercises may play a part in the prevention of bone loss in these patients. PMID:11874835

  11. Photon absorptiometry for non-invasive measurement of bone mineral content

    SciTech Connect

    Gupta, S.; Luna, E.; Belsky, J.; Gelfman, N.; Miller, K.; Davies, T.

    1984-08-01

    Bone mineral content of the distal radius was determined in 106 patients by single photon absorptiometry using iodine-125 monochromatic source. The technique provided a reliable means to assess the degree of mineral loss in conditions such as osteoporosis, renal osteodystrophy in patients on chronic maintenance dialysis, subjects on long-term steroid therapy, and those with diabetes mellitus. It is more sensitive than conventional radiography and completely noninvasive compared to bone biopsy. It is suggested that photon absorptiometry is a simple, sensitive, and reliable technique for assessment and follow-up of the bone mineral content in a host of disorders associated with bone demineralization.

  12. Body composition of Native-American women estimated by dual-energy X-ray absorptiometry and hydrodensitometry.

    PubMed

    Hicks, V L; Heyward, V H; Baumgartner, R N; Flores, A J; Stolarczyk, L M; Wotruba, E A

    1993-01-01

    In the present sample, the Native-American women varied in age (18-60 y) and fatness (23.0-57.4% BF). The cross-validation analysis for %BF estimated by DXA for this sample yielded a high validity coefficient (r = 0.89), and the average %BFDXA (37.3%) and %BFHW (37.6%) did not differ significantly. The prediction error (3.28% BF) was less than the theoretical expected value, given the wide range in age and fatness in this sample. Thus, it appears that DXA may be a viable alternative method for estimating the %BF of a diverse group of Native-American women. The DXA method is more practical than hydrostatic weighing, especially for subjects who are uncomfortable in the water. Also, DXA estimates of bone mineral may lead to improved estimates of FFB density for different ethnic populations. PMID:8110173

  13. Validation of a New Skinfold Prediction Equation Based on Dual-Energy X-Ray Absorptiometry

    ERIC Educational Resources Information Center

    Ball, Stephen; Cowan, Celsi; Thyfault, John; LaFontaine, Tom

    2014-01-01

    Skinfold prediction equations recommended by the American College of Sports Medicine underestimate body fat percentage. The purpose of this research was to validate an alternative equation for men created from dual energy x-ray absorptiometry. Two hundred ninety-seven males, aged 18-65, completed a skinfold assessment and dual energy x-ray…

  14. Bone Indices in Thyroidectomized Patients on Long-Term Substitution Therapy with Levothyroxine Assessed by DXA and HR-pQCT

    PubMed Central

    Moser, Emil; Sikjaer, Tanja; Mosekilde, Leif; Rejnmark, Lars

    2015-01-01

    Background. Studies on bone effects of long-term substitution therapy with levothyroxine (LT4) have shown discrepant results. Previous studies have, however, not evaluated volumetric bone mineral densities (vBMD), bone structure, and strength using high resolution peripheral quantitative computed tomography (HR-pQCT) and finite element analysis (FEA). Using a cross-sectional design, we aimed to determine whether BMD, structure, and strength are affected in hypothyroid patients on LT4 substitution therapy. Methods. We compared 49 patients with well-substituted hypothyroidism with 49 age- and gender-matched population based controls. Areal BMD was assessed by DXA, vBMD and bone geometry by HR-pQCT, and bone strength by FEA. Results. Patients had been thyroidectomized due to thyroid cancer (10%) and nontoxic (33%) or toxic goiter (57%). 82% were women. TSH levels did not differ between groups, but patients had significantly higher levels of T4 (p < 0.001) and lower levels of T3 (p < 0.01). Compared to controls, patients had higher levels of magnesium (p < 0.05), whereas ionized calcium and PTH were lower (p < 0.05). Bone scans did not reveal any differences in BMD, bone geometry, or strength. Conclusion. If patients with hypothyroidism are well-substituted with LT4, the disease does not affect bone indices to any major degree. PMID:26246934

  15. Comparison of dual-photon absorptiometry systems for total-body bone and soft tissue measurements: Dual-energy X-rays versus gadolinium 153

    SciTech Connect

    Russell-Aulet, M.; Wang, J.; Thornton, J.; Pierson, R.N. Jr. )

    1991-04-01

    A total of 81 subjects (41 males and 40 females) were scanned by dual-photon absorptiometry by 153Gd source (DPA; Lunar DP4) and by dual-energy x-ray absorptiometry (DEXA; Lunar-DPX) within a 24 h period. Total-body bone mineral density (TBMD), calcium content (Ca), and soft tissue mass (ST) were determined with a precision of about 1-1.5% using DPA and 0.5-1.0% using DEXA. Measurements of TBMD, Ca, ST, bone area (area), percentage fat, and regional bone mineral densities (BMD) were compared. Paired t-tests showed small but significant differences between all measurements. Correlations (r) for TBMD, Ca, area, ST, percentage fat, arm BMD, leg BMD, and trunk BMD were 0.99, 0.99, 0.97, 0.99, 0.97, 0.99, 0.99, and 0.98. There were small systematic differences for TBMD (less than 1%), calcium (3%), bone area (3%), soft tissue mass (7%), and percentage fat (9%) between the two approaches. Regression equations are given relating these measurements.

  16. Relationship between body mass index and bone mineral density in HIV-infected patients referred for DXA

    PubMed Central

    Pinnetti, Carmela; Federico, Lupi; Lorenzini, Patrizia; Domenico, Chiappetta; Rita, Bellagamba; Laura, Loiacono; Zaccarelli, Mauro; Cicalini, Stefania; Libertone, Raffaella; Giannetti, Alberto; Mosti, Silvia; Busi Rizzi, Elisa; Antinori, Andrea; Ammassari, Adriana

    2014-01-01

    Introduction Reduced bone mass density (BMD) is a frequent observation in HIV-infected persons. Relationship between body mass index (BMI), weight, height and BMD was reported for many populations. In particular, BMI has been found to be inversely related to the risk of osteoporosis. Methods This is a cross-sectional, monocentric study where all HIV-infected patients referred to first DXA scan in clinical routine during 2010–2013 were included. Osteopenia and osteoporosis were defined by T- score <−1 and <−2.5, respectively. Patients were categorized according to WHO BMI classification: underweight <18.5 kg/m2; normal weight 18.5–24.9 kg/m2; over weight 25–29.9 kg/m2; obese >30 kg/m2. Statistical analysis was carried using logistic regression. Results A total of 918 patients were included: median age 49 years (IQR, 44–55); 59.4% male; 93% Caucasian. Median anthrometric characteristics were: 68 kg (IQR, 59–78); 1.7 m (IQR, 1.6–1.75); 23.5 kg/m2 (IQR, 21.4–26.2). Underweight was found in 5%, normal weight in 61%, overweight in 26% and obesity in 8% of patients. According to T-scores, 110 (11.2%) patients were osteoporotic and 502 (54.7%) had osteopenia. In the femoral neck area, the prevalence of osteoporosis was slightly lower (5.7%) than lumbar spine site (9.2%). Agreements between sites of T-scores for the diagnosis of osteoporosis were 26 and 172 and 346 for osteopenia and normal BMD values, respectively. T-scores at femoral neck or lumbar spine positively correlated with BMI (p<0.001) (Figure 1). Among predictors of osteopenia/osteoporosis, univariable analysis showed: older age (p<0.0001); lower weight (p<0.0001); increasing height (p<0.002). Patients underweight had a higher risk of osteopenia (p=0.02) as well as of osteoporosis (p=0.003). Patients with BMI above normal had a reduced risk of low BMD (osteopenia p<0.0001; osteoporosis p<0.03). Controlling for calendar year, gender, ethnicity, and age, BMI was confirmed as risk factor if below

  17. Determination of radial bone mineral content in low birth weight infants by photon absorptiometry

    SciTech Connect

    Greer, F.R.

    1988-07-01

    Studies at the University of Wisconsin have demonstrated that photon absorptiometry is a precise, accurate, and reproducible technique for measuring bone mineral content in premature infants and can be used to establish an intrauterine curve of bone mineralization in the fetus. Photon absorptiometry can also be used to measure bone width, thereby documenting appositional bone growth. The bone mineral content/bone width ratio may be helpful in identifying disorders of bone mineral metabolism in premature infants. The technique has been used to demonstrate that relatively poor bone mineralization (compared with the intrauterine curve) occurs in very low birth weight infants after birth, regardless of the type of feeding or the presence or absence of bronchopulmonary dysplasia. 31 references.

  18. Measurement of the subcutaneous fat in the distal forearm by single photon absorptiometry

    SciTech Connect

    Hassager, C.; Borg, J.; Christiansen, C.

    1989-02-01

    The influence of subcutaneous fat on single photon (/sup 125/I) absorptiometry (SPA) measurement of bone mineral content of the distal forearm was investigated. A fat correction model was tested by measurements on eight lean subjects with different amounts of porcine fat around their forearm, and further validated from measurements on 128 females. In addition, it is shown that the fat content in the distal forearm can be measured by SPA with a short-term precision at 1.9% in an obese subject and that it correlates well with total body fat (r2 = .7) measured by dual photon absorptiometry, skinfold thickness (r2 = .5), and body mass index (r2 = .6). By using this method in a double-blind placebo-controlled trial, hormonal substitutional therapy significantly decreased the forearm fat content without affecting the body weight in postmenopausal osteoporotic women.

  19. Measurement of spine and total body mineral by dual-photon absorptiometry

    NASA Technical Reports Server (NTRS)

    Mazess, R. B.; Young, D.

    1983-01-01

    The use of Gd-153 dual-photon absorptiometry at 43 and 100 keV to measure individual-bone and total-body bone minerals is discussed in a survey of recent studies on humans, phantoms, and monkeys. Precision errors of as low as 1 percent have been achieved in vivo, suggesting the use of sequential measurements in studies of immobilization and space-flight effects.

  20. Precision error in dual-photon absorptiometry related to source age

    SciTech Connect

    Ross, P.D.; Wasnich, R.D.; Vogel, J.M.

    1988-02-01

    An average, variable precision error of up to 6% related to source age was observed for dual-photon absorptiometry of the spine in a longitudinal study of bone mineral content involving 393 women. Application of a software correction for source decay compensated for only a portion of this error. The authors conclude that measurement of bone-loss rates using serial dual-photon bone mineral measurements must be interpreted with caution.

  1. Fracture Risk Prediction by Non-BMD DXA Measures: the 2015 ISCD Official Positions Part 1: Hip Geometry.

    PubMed

    Broy, Susan B; Cauley, Jane A; Lewiecki, Michael E; Schousboe, John T; Shepherd, John A; Leslie, William D

    2015-01-01

    Bone mineral density (BMD) measured by dual-energy X-ray absorptiometry is the current imaging procedure of choice to assess fracture risk. However, BMD is only one of the factors that explain bone strength or resistance to fracture. Other factors include bone microarchitecture and macroarchitecture. We now have the ability to assess some of these non-BMD parameters from a dual-energy X-ray absorptiometry image. Available measurements include various measurements of hip geometry including hip structural analysis, hip axis length, and neck-shaft angle. At the 2015 Position Development Conference, the International Society of Clinical Densitometry established official positions for the clinical utility of measurements of hip geometry. We present the official positions approved by an expert panel after careful review of the recommendations and evidence prepared by an independent task force. Each question addressed by the task force is presented followed by the official position with the associated medical evidence and rationale. PMID:26277848

  2. Thyroid scan

    MedlinePlus

    ... thyroid; Radioactive iodine uptake and scan test - thyroid; Nuclear scan - thyroid ... the test. Ask your provider or the radiology/nuclear medicine team performing the scan about taking precautions.

  3. Nuclear Scans

    MedlinePlus

    Nuclear scans use radioactive substances to see structures and functions inside your body. They use a special ... images. Most scans take 20 to 45 minutes. Nuclear scans can help doctors diagnose many conditions, including ...

  4. The effect of extending femur scan length on BMD results on the Hologic Discovery-W scanner.

    PubMed

    Prater, Ginnie L; Jankowski, Lawrence G; Peace, Frederick; Nunnally, Nancy; Burroughs, Leandria; Morgan, Sarah L

    2014-01-01

    A longer dual-energy X-ray absorptiometry scan field of the hip may be useful for the detection of atypical subtrochanteric femur fractures. It has been demonstrated in a Prodigy GE/Lunar scanner that extending the scan length does not affect bone mineral density (BMD) results at the total hip or femoral neck. We hypothesized that extending the scan field on a Hologic Discovery scanner would also have no effect on BMD results at the hip. Thirty subjects who presented for standard of care dual-energy X-ray absorptiometry scans underwent paired default (15.2 cm) and extended (24.1 cm) length hip scans. There was no significant difference in the total hip or any of the component subregions of femoral neck, greater trochanter, or intertrochanteric (shaft) BMD between the default and extended length scans.

  5. Treatment of subclinical hypothyroidism does not affect bone mass as determined by dual-energy X-ray absorptiometry, peripheral quantitative computed tomography and quantitative bone ultrasound in Spanish women

    PubMed Central

    Roncero-Martin, Raul; Calderon-Garcia, Julian F.; Santos-Vivas, Mercedes; Vera, Vicente; Martínez-Alvárez, Mariana; Rey-Sanchez, Purificación

    2015-01-01

    Introduction The results of studies examining the influence of subclinical hypothyroidism (SCH) and levothyroxine (L-T4) replacement therapy on bone have generated considerable interest but also controversy. The present research aims to evaluate the effects of L-T4 treatment on different skeletal sites in women. Material and methods A group of 45 premenopausal (mean age: 43.62 ±6.65 years) and 180 postmenopausal (mean age: 59.51 ±7.90 years) women with SCH who were undergoing L-T4 replacement therapy for at least 6 months were compared to 58 pre- and 180 postmenopausal women with SCH (untreated) matched for age. The mean doses of L-T4 were 90.88 ±42.59 µg/day in the premenopausal women and 86.35 ±34.11 µg/day in the postmenopausal women. Bone measurements were obtained using quantitative bone ultrasound (QUS) for the phalanx, dual-energy X-ray absorptiometry (DXA) for the lumbar spine and hip, and peripheral quantitative computed tomography (pQCT) for the non-dominant distal forearm. Results No differences were observed between patients and untreated controls in these bone measurements except in the bone mineral density (BMD) of the spine (p = 0.0214) in postmenopausal women, which was greater in treated women than in untreated controls. Conclusions Our results indicate that adequate metabolic control through replacement treatment with L-T4 in pre- and postmenopausal women does not affect bone mass. PMID:26528344

  6. Gallium scan

    MedlinePlus

    Liver gallium scan; Bony gallium scan ... You will get a radioactive material called gallium injected into your vein. The gallium travels through the bloodstream and collects in the bones and certain organs. Your health care provider will ...

  7. Bone scanning.

    PubMed

    Greenfield, L D; Bennett, L R

    1975-03-01

    Scanning is based on the uptake of a nuclide by the crystal lattice of bone and is related to bone blood flow. Cancer cells do not take up the tracer. Normally, the scan visualizes the highly vascular bones. Scans are useful and are indicated in metastatic bone disease, primary bone tumors, hematologic malignancies and some non-neoplastic diseases. The scan is more sensitive than x-ray in the detection of malignant diseases of the skeleton. PMID:1054210

  8. Ultrasound-Derived Forearm Muscle Thickness Is a Powerful Predictor for Estimating DXA-Derived Appendicular Lean Mass in Japanese Older Adults.

    PubMed

    Abe, Takashi; Fujita, Eiji; Thiebaud, Robert S; Loenneke, Jeremy P; Akamine, Takuya

    2016-09-01

    To test the validity of published equations, anterior forearm muscle thickness (MT-ulna) of 158 Japanese older adults (72 men and 86 women) aged 50-79 y was measured with ultrasound. Appendicular lean soft tissue mass (aLM) was estimated from MT-ulna using two equations (body height without [eqn 1] and with [eqn 2]) previously published in the literature. Appendicular lean mass was measured using dual-energy X-ray absorption (DXA), and this method served as the reference criterion. There was a strong correlation between DXA-derived and ultrasound-estimated aLM in both equations (r = 0.882 and r = 0.944). Total error was 2.60 kg for eqn (1) and 1.38 kg for eqn (2). A Bland-Altman plot revealed that there was no systematic bias between DXA-derived and ultrasound-estimated aLM; however, eqn (1) overestimated aLM compared with DXA-derived aLM. Our results suggest that an ultrasound MT-ulna equation that includes body height is appropriate and useful for estimating aLM in Japanese adults. PMID:27321173

  9. Techniques for deriving tissue structure from multiple projection dual-energy x-ray absorptiometry

    NASA Technical Reports Server (NTRS)

    Charles, Jr., Harry K. (Inventor); Beck, Thomas J. (Inventor); Feldmesser, Howard S. (Inventor); Magee, Thomas C. (Inventor)

    2004-01-01

    Techniques for deriving bone properties from images generated by a dual-energy x-ray absorptiometry apparatus include receiving first image data having pixels indicating bone mineral density projected at a first angle of a plurality of projection angles. Second image data and third image data are also received. The second image data indicates bone mineral density projected at a different second angle. The third image data indicates bone mineral density projected at a third angle. The third angle is different from the first angle and the second angle. Principal moments of inertia for a bone in the subject are computed based on the first image data, the second image data and the third image data. The techniques allow high-precision, high-resolution dual-energy x-ray attenuation images to be used for computing principal moments of inertia and strength moduli of individual bones, plus risk of injury and changes in risk of injury to a patient.

  10. Body Composition Comparison: Bioelectric Impedance Analysis with Dual-Energy X-Ray Absorptiometry in Adult Athletes

    ERIC Educational Resources Information Center

    Company, Joe; Ball, Stephen

    2010-01-01

    The primary purpose of this study was to investigate the accuracy of the DF50 (ImpediMed Ltd, Eight Mile Plains, Queensland, Australia) bioelectrical impedance analysis device using dual-energy x-ray absorptiometry as the criterion in two groups: endurance athletes and power athletes. The secondary purpose was to develop accurate body fat…

  11. Assessing Body Composition of Children and Adolescents Using Dual-Energy X-Ray Absorptiometry, Skinfolds, and Electrical Impedance

    ERIC Educational Resources Information Center

    Mooney, Angela; Kelsey, Laurel; Fellingham, Gilbert W.; George, James D.; Hager, Ron L.; Myrer, J. William; Vehrs, Pat R.

    2011-01-01

    To determine the validity and reliability of percent body fat estimates in 177 boys and 154 girls between 12-17 years of age, percent body fat was assessed once using dual-energy X-ray absorptiometry and twice using the sum of two skinfolds and three bioelectrical impedance analysis devices. The assessments were repeated on 79 participants on a…

  12. Friend or foe: high bone mineral density on routine bone density scanning, a review of causes and management

    PubMed Central

    Hardcastle, Sarah A.; Cooper, Cyrus; Tobias, Jonathan H.

    2013-01-01

    A finding of high BMD on routine DXA scanning is not infrequent and most commonly reflects degenerative disease. However, BMD increases may also arise secondary to a range of underlying disorders affecting the skeleton. Although low BMD increases fracture risk, the converse may not hold for high BMD, since elevated BMD may occur in conditions where fracture risk is increased, unaffected or reduced. Here we outline a classification for the causes of raised BMD, based on identification of focal or generalized BMD changes, and discuss an approach to guide appropriate investigation by clinicians after careful interpretation of DXA scan findings within the context of the clinical history. We will also review the mild skeletal dysplasia associated with the currently unexplained high bone mass phenotype and discuss recent advances in osteoporosis therapies arising from improved understanding of rare inherited high BMD disorders. PMID:23445662

  13. Standards and measurements for assessing bone health-workshop report co-sponsored by the International Society for Clinical Densitometry (ISCD) and the National Institute of Standards and Technology (NIST).

    PubMed

    Bennett, Herbert S; Dienstfrey, Andrew; Hudson, Lawrence T; Oreskovic, Tammy; Fuerst, Thomas; Shepherd, John

    2006-01-01

    This article reports and discusses the results of the recent ISCD-NIST Workshop on Standards and Measurements for Assessing Bone Health. The purpose of the workshop was to assess the status of efforts to standardize and compare results from dual-energy X-ray absorptiometry (DXA) scans, and then to identify and prioritize ongoing measurement and standards needs.

  14. MRI Scans

    MedlinePlus

    Magnetic resonance imaging (MRI) uses a large magnet and radio waves to look at organs and structures inside your body. Health care professionals use MRI scans to diagnose a variety of conditions, from torn ...

  15. WBC scan

    MedlinePlus

    Leukocyte scan ... will be taken from one of your veins. White blood cells are separated from the rest of the blood ... 111. These cells are considered tagged. The tagged white blood cells are injected back into your body through a ...

  16. New segmental long bone defect model in sheep: quantitative analysis of healing with dual energy x-ray absorptiometry.

    PubMed

    den Boer, F C; Patka, P; Bakker, F C; Wippermann, B W; van Lingen, A; Vink, G Q; Boshuizen, K; Haarman, H J

    1999-09-01

    An appropriate animal model is required for the study of treatments that enhance bone healing. A new segmental long bone defect model was developed for this purpose, and dual energy x-ray absorptiometry was used to quantify healing of this bone defect. In 15 sheep, a 3-cm segmental defect was created in the left tibia and fixed with an interlocking intramedullary nail. In seven animals, the defect was left empty for the assessment of the spontaneous healing response. In eight animals serving as a positive control, autologous bone grafting was performed. After 12 weeks, healing was evaluated with radiographs, a torsional test to failure, and dual energy x-ray absorptiometry. The mechanical test results were used for the assessment of unions and nonunions. Radiographic determination of nonunion was not reliably accomplished in this model. By means of dual energy x-ray absorptiometry, bone mineral density and content were measured in the middle of the defect. Bone mineral density was 91+/-7% (mean +/- SEM) and 72+/-6% that of the contralateral intact tibia in, respectively, the autologous bone-grafting and empty defect groups (p = 0.04). For bone mineral content, the values were, respectively, 117+/-18 and 82+/-9% (p = 0.07). Torsional strength and stiffness were also higher, although not significantly, in the group with autologous bone grafting than in that with the empty defect. Bone mineral density and content were closely related to the torsional properties (r2 ranged from 0.76 to 0.85, p < or = 0.0001). Because interlocking intramedullary nailing is a very common fixation method in patients, the newly developed segmental defect model has clinical relevance. The interlocking intramedullary nail provided adequate stability without implant failure. This model may be useful for the study of treatments that affect bone healing, and dual energy x-ray absorptiometry may be somewhat helpful in the analysis of healing of this bone defect.

  17. Double-energy X-ray absorptiometry in the diagnosis of osteopenia in ancient skeletal remains.

    PubMed

    González-Reimers, E; Velasco-Vázquez, J; Arnay-de-la-Rosa, M; Santolaria-Fernández, F; Gómez-Rodríguez, M A; Machado-Calvo, M

    2002-06-01

    Bone mineral density (BMD) assessed by double-energy X-ray absorptiometry (DEXA) accurately estimates the bone mass in living individuals, and is thus the method usually employed in the diagnosis and follow-up of osteopenia. It is preferred, in clinical settings, to the more invasive and destructive histomorphometrical assessment of trabecular bone mass in undecalcified bone samples. This study was performed in order to examine the value of DEXA-assessed BMD at the proximal end of the right tibia, either alone or in combination with the cortico-medullary index at the midshaft point of the right tibia (CMI), in the diagnosis of osteopenia in a prehistoric sample composed of 95 pre-Hispanic individuals from Gran Canaria. Age at death could be estimated in 34 cases. Diagnosis of osteopenia was performed by histomorphometrical assessment of trabecular bone mass (TBM) in an undecalcified bone section of a small portion of the proximal epiphysis of the right tibia. A high prevalence of osteopenia was found among the population of Gran Canaria. Both TBM and BMD were significantly lower in the older individuals than in younger ones, and BMD was also significantly lower in female individuals. BMD was moderately correlated with TBM (r = +0.51); the correlation was higher if CMI was included (multiple r = +0.615). BMD values lower than 0.7 g/cm2 showed a high specificity (>93%) at excluding normal TBM values. These methods were prospectively applied in a further sample of 21 right tibiae from Gran Canaria, Tenerife, and El Hierro. The results were similar to those obtained in the larger sample. Thus, DEXA-assessed BMD combined with CMI (noninvasive procedures) may be useful in detecting osteopenia in ancient populations.

  18. Accuracy of lumbar spine bone mineral content by dual photon absorptiometry

    SciTech Connect

    Gotfredsen, A.; Podenphant, J.; Norgaard, H.; Nilas, L.; Nielsen, V.A.; Christiansen, C.

    1988-02-01

    The accuracy of measurement of the bone mineral content (BMC, g) and bone mineral density (BMD, g/cm/sup 2/) of the lumbar spine by dual photon absorptiometry (DPA) was estimated by means of two different spine scanners (a Nuclear Data 2100 and a Lunar Radiation DP3). The lumbar spines of 13 cadavers were used. BMC and BMD were measured in situ and on the excised vertebrae in a solution of water/ethanol; and covered with ox muscle/porcine muscle/lard. The actual mineral weight and areal density were determined after chemical maceration, fat extraction, drying to a constant weight, ashing for 24 hr at 600 degrees C, and correction for the transverse processes. The true are was measured by parallax free X rays and planimetry. All measurements of BMC or BMD were highly interrelated (r = 0.94-0.99). The standard error of estimate (s.e.e.) of BMC in situ versus BMC in water/ethanol was 5.2%. The agreement between the BMD values of the two scanners was very good (s.e.e. = 2.9%). BMC in situ predicted the actual vertebral mineral mass with an s.e.e. of 8.1%. BMD in situ and BMD in water/ethanol predicted the actual area density with s.e.e.s of 10.3% and 5.0%, respectively. This study discloses the correlation and accuracy error of spinal DPA measurements in situ in whole cadavers versus the actual BMC and BMD. The error, which is underestimated in in vitro studies, amounts to 10%.

  19. Perineal scanning.

    PubMed

    Jeanty, P; d'Alton, M; Romero, R; Hobbins, J C

    1986-10-01

    Although various techniques have been described to aid in the ultrasound diagnosis of placenta previa and incompetent cervix, these maneuvers depend on the precise identification of the internal cervical os, a feat which is notoriously difficult to accomplish consistently. In an attempt to get a closer view of the cervix we tried another approach. This simple technique of perineal scanning has the potential to help considerably with these problems. PMID:3530265

  20. Study of sex differences in the association between hip fracture risk and body parameters by DXA-based biomechanical modeling.

    PubMed

    Nasiri, Masoud; Luo, Yunhua

    2016-09-01

    There is controversy about whether or not body parameters affect hip fracture in men and women in the same way. In addition, although bone mineral density (BMD) is currently the most important single discriminator of hip fracture, it is unclear if BMD alone is equally effective for men and women. The objective of this study was to quantify and compare the associations of hip fracture risk with BMD and body parameters in men and women using our recently developed two-level biomechanical model that combines a whole-body dynamics model with a proximal-femur finite element model. Sideways fall induced impact force of 130 Chinese clinical cases, including 50 males and 80 females, were determined by subject-specific dynamics modeling. Then, a DXA-based finite element model was used to simulate the femur bone under the fall-induced loading conditions and calculate the hip fracture risk. Body weight, body height, body mass index, trochanteric soft tissue thickness, and hip bone mineral density were determined for each subject and their associations with impact force and hip fracture risk were quantified. Results showed that the association between impact force and hip fracture risk was not strong enough in both men (r=-0.31,p<0.05) and women (r=0.42,p<0.001) to consider the force as a sole indicator of hip fracture risk. The correlation between hip BMD and hip fracture risk in men (r=-0.83,p<0.001) was notably stronger than that in women (r=-0.68,p<0.001). Increased body mass index was not a protective factor against hip fracture in men (r=-0.13,p>0.05), but it can be considered as a protective factor among women (r=-0.28,p<0.05). In contrast to men, trochanteric soft tissue thickness can be considered as a protective factor against hip fracture in women (r=-0.50,p<0.001). This study suggested that the biomechanical risk/protective factors for hip fracture are sex-specific. Therefore, the effect of body parameters should be considered differently for men and women in hip

  1. Head CT scan

    MedlinePlus

    Brain CT; Cranial CT; CT scan - skull; CT scan - head; CT scan - orbits; CT scan - sinuses; Computed tomography - cranial; CAT scan - brain ... conditions: Birth (congenital) defect of the head or brain Brain infection Brain tumor Buildup of fluid inside ...

  2. Pelvic CT scan

    MedlinePlus

    CAT scan - pelvis; Computed axial tomography scan - pelvis; Computed tomography scan - pelvis; CT scan - pelvis ... creates detailed pictures of the body, including the pelvis and areas near the pelvis. The test may ...

  3. Leg CT scan

    MedlinePlus

    CAT scan - leg; Computed axial tomography scan - leg; Computed tomography scan - leg; CT scan - leg ... on film. Three-dimensional (3D) models of the leg can be created by adding the slices together. ...

  4. Abscess scan - radioactive

    MedlinePlus

    Radioactive abscess scan; Abscess scan; Indium Scan; Indium-labelled white blood cell scan ... the white blood cells are tagged with a radioactive substance called indium. The cells are then injected ...

  5. A comparison of dual energy x-ray absorptiometry and two bioelectrical impedance analyzers to measure body fat percentage and fat-free mass index in a group of Mexican young women.

    PubMed

    Velazquez-Alva, Maria Del Consuelo; Irigoyen-Camacho, Maria Esther; Huerta-Huerta, Raquel; Delgadillo-Velazquez, Jaime

    2014-05-01

    Introducción: Los estudios de obesidad requieren estimación de masa grasa (FM) y masa libre de grasa (FFM). Objetivo: Comparar dos equipos de impedancia bioeléctrica (BIA) para estimar FM y FFM usando absorciometría de rayos X de energía dual (DXA) como referencia. Métodos: Estudio transversal. FM y FFM fueron evaluados por DXA y BIA: sistema pie-pie (FFS) y sistema mano-pie (HFS). Se realizaron pruebas t pareadas, coeficientes de correlación y análisis de Bland y Altman. Limites de acuerdo fueron calculados (CL). Resultados: Fueron estudiadas 175 mujeres (22,9 ± 2,2 años). Hubo diferencias significativas entre el promedio del porcentaje de grasa estimado por los equipos de BIA en comparación con DXA (FFS = 28,7%, HFS = 34,4% y DXA = 35,3%). La diferencia de medias del porcentaje de grasa entre HFS y DXA fue -0.96, (CL -5,29, 7,21). La diferencia de medias para FFS fue de -6,69,(CL -0,29, - 13.09) Hubo diferencias significativas entre las estimaciones de FFMI por BIA y DXA (FFS = 16,29, HFS = 14,95, DXA = 14,18). La diferencia de medias entre HFS y DXA fue = 0,78, (CL -2,27, 0,72) y la diferencia de medias de FFS fue -2,11: (CL -3,73 , -0,49). Conclusiones: Niveles diferentes de sesgo se observaron entre los equipos de BIA. El HFS parece ser más confiable que el FFS, sobre todo en la obtención de FFMI en mujeres jóvenes.

  6. Bone mineral measurements: a comparison of delayed gamma neutron activation, dual-energy X-ray absorptiometry and direct chemical analysis.

    PubMed

    Economos, C D; Nelson, M E; Fiatarone Singh, M A; Kehayias, J J; Dallal, G E; Heymsfield, S B; Wang, J; Yasumura, S; Ma, R; Pierson, R N

    1999-01-01

    A system in vitro consisting of a femur from a cadaver and soft-tissue equivalent material was used to test the agreement between several techniques for measuring bone mineral. Calcium values measured by delayed gamma neutron activation (DGNA) and bone mineral content (BMC) by Lunar, Hologic and Norland dual-energy X-ray absorptiometers (DXA) were compared with calcium and ash content determined by direct chemical analysis. To assess the effect of soft-tissue thickness on measurements of bone mineral, we had three phantom configurations ranging from 15.0 to 26.0 cm in thickness, achieved by using soft-tissue equivalent overlays. Chemical analysis of the femur gave calcium and ash content values of 61.83 g +/- 0.51 g and 154.120 +/- 0.004 g, respectively. Calcium measured by DGNA did not differ from the ashed amount of calcium at any of the phantom configurations. The BMC measured by DXA was significantly higher, by 3-5%, than the amount determined by chemical analysis for the Lunar densitometer and significantly lower, by 3-6%, for the Norland densitometer (p<0.001-0.024), but only 1% lower (not significant) for the Hologic densitometer. DXA instruments showed a decreasing trend in BMC as the thickness increased from 20.5 to 26.0 cm (p<0.05). However, within the entire thickness range (15.0-26.0 cm), the overall influence of thickness on BMC by DXA was very small. These findings offer insight into the differences in these currently available methods for bone mineral measurement and challenge the comparability of different methods. PMID:10525711

  7. Dual-energy X-ray absorptiometry–based body volume measurement for 4-compartment body composition123

    PubMed Central

    Wilson, Joseph P; Mulligan, Kathleen; Fan, Bo; Sherman, Jennifer L; Murphy, Elizabeth J; Tai, Viva W; Powers, Cassidy L; Marquez, Lorena; Ruiz-Barros, Viviana

    2012-01-01

    Background: Total body volume (TBV), with the exclusion of internal air voids, is necessary to quantify body composition in Lohman's 4-compartment (4C) model. Objective: This investigation sought to derive a novel, TBV measure with the use of only dual-energy X-ray absorptiometry (DXA) attenuation values for use in Lohman's 4C body composition model. Design: Pixel-specific masses and volumes were calculated from low- and high-energy attenuation values with the use of first principle conversions of mass attenuation coefficients. Pixel masses and volumes were summed to derive body mass and total body volume. As proof of concept, 11 participants were recruited to have 4C measures taken: DXA, air-displacement plethysmography (ADP), and total body water (TBW). TBV measures with the use of only DXA (DXA-volume) and ADP-volume measures were compared for each participant. To see how body composition estimates were affected by these 2 methods, we used Lohman's 4C model to quantify percentage fat measures for each participant and compared them with conventional DXA measures. Results: DXA-volume and ADP-volume measures were highly correlated (R2 = 0.99) and showed no statistically significant bias. Percentage fat by DXA volume was highly correlated with ADP-volume percentage fat measures and DXA software-reported percentage fat measures (R2 = 0.96 and R2 = 0.98, respectively) but were slightly biased. Conclusions: A novel method to calculate TBV with the use of a clinical DXA system was developed, compared against ADP as proof of principle, and used in Lohman's 4C body composition model. The DXA-volume approach eliminates many of the inherent inaccuracies associated with displacement measures for volume and, if validated in larger groups of participants, would simplify the acquisition of 4C body composition to a single DXA scan and TBW measure. PMID:22134952

  8. Regional variation in the denial of reimbursement for bone mineral density testing among US Medicare beneficiaries.

    PubMed

    Curtis, Jeffrey R; Laster, Andrew J; Becker, David J; Carbone, Laura; Gary, Lisa C; Kilgore, Meredith L; Matthews, Robert; Morrisey, Michael A; Saag, Kenneth G; Tanner, S Bobo; Delzell, Elizabeth

    2008-01-01

    Although the Bone Mass Measurement Act outlines the indications for central dual-energy X-ray absorptiometry (DXA) testing for US Medicare beneficiaries, the specifics regarding the appropriate ICD-9 codes to use for covered indications have not been specified by Medicare and are sometimes ambiguous. We describe the extent to which DXA reimbursement was denied by gender and age of beneficiary, ICD-9 code submitted, time since previous DXA, whether the scan was performed in the physician's office and local Medicare carrier. Using Medicare administrative claims data from 1999 to 2005, we studied a 5% national sample of beneficiaries age > or =65 yr with part A+B coverage who were not health maintenance organization enrollees. We identified central DXA claims and evaluated the relationship between the factors listed above and reimbursement for central DXA (CPT code 76075). Multivariable logistic regression was used to evaluate the independent relationship between DXA reimbursement, ICD-9 diagnosis code, and Medicare carrier. For persons who had no DXA in 1999 or 2000 and who had 1 in 2001 or 2002, the proportion of DXA claims denied was 5.3% for women and 9.1% for men. For repeat DXAs performed within 23 mo, the proportion denied was approximately 19% and did not differ by sex. Reimbursement varied by more than 6-fold according to the ICD-9 diagnosis code submitted. For repeat DXAs performed at <23 mo, the proportion of claims denied ranged from 2% to 43%, depending on Medicare carrier. Denial of Medicare reimbursement for DXA varies significantly by sex, time since previous DXA, ICD-9 diagnosis code submitted, place of service (office vs facility), and local Medicare carrier. Greater guidance and transparency in coding policies are needed to ensure that DXA as a covered service is reimbursed for Medicare beneficiaries with the appropriate indications.

  9. Description and performance comparison of commercial and prototype dual photon absorptiometry (DPA) systems

    SciTech Connect

    Dunn, W.L.; Wahner, H.W.

    1985-05-01

    DPA has become of major interest for clinical measurements of bone mineral (BM) in the axial skeleton. Several commercial instruments are now available. The objective of this paper is a description and comparison of these instruments with some of the instruments used in clinical research laboratories. /sup 153/Gd is almost exclusively used as a source (1-1.5Ci). All instruments use NaI(T1) detectors. Detector collimator sizes vary from about 0.6 to 1.3 cm diameter. Linearity, accuracy and reproducibility of BM measurements were evaluated by scanning a series of ashed bones in 20 cm of water. Reproducibility was studied by performing multiple scans of ashed bones and a cadaver spine, CV being less than 2.1% for the spine. Minimum performance criteria for a clinical bone mineral test is a reproducibility of less than 3%. Dosimetry studies conducted to date show a peak skin dose of 18 mrad (0.18mGy). Additional dosimetry measurements are presently being performed. The authors conclude that the commercial DPA units provide results which are clinically acceptable and comparable to the prototype systems.

  10. Gallbladder radionuclide scan

    MedlinePlus

    Radionuclide - gallbladder; Gallbladder scan; Biliary scan; Cholescintigraphy: HIDA; Hepatobiliary nuclear imaging scan ... small amount of morphine. This can help the radionuclide get into the gallbladder. The morphine may cause ...

  11. Coronary Calcium Scan

    MedlinePlus

    ... the NHLBI on Twitter. What Is a Coronary Calcium Scan? A coronary calcium scan is a test ... you have calcifications in your coronary arteries. Coronary Calcium Scan Figure A shows the position of the ...

  12. A DXA study of muscle-bone relationships in the whole body and limbs of 2512 normal men and pre- and post-menopausal women.

    PubMed

    Capozza, R F; Cointry, G R; Cure-Ramírez, P; Ferretti, J L; Cure-Cure, C

    2004-07-01

    A whole-body DXA study of 1450 healthy Caucasian individuals [Bone 22 (1998) 683] found that mineral mass, either crude (BMC) or statistically adjusted to fat mass (FM-adjusted BMC), correlated linearly with lean mass (LM, proportional to muscle mass). The results showed similar slopes but decreasing intercepts (ordinate values) in the order: pre-MP women > men > post-MP women > children. This supports the hypothesis that sex hormones influence the control of bone status by muscle strength in all species. Now we further study those relationships in 2512 healthy Hispanic adults (307 men, 753 pre-MP women, 1452 post-MP women), including separate determinations in their upper and lower limbs. The slopes of the BMC or FM-adjusted BMC vs. LM relationships were parallel in all the studied regions. However, region-related differences were found between the ordinates of the curves. In the whole body, the crude-BMC/LM relationships showed the same ordinate differences as previously observed. In the lower limbs, those differences were smaller in magnitude but highly significant, showing the order: pre-MP women > men = post-MP women. In the upper limbs, the decreasing ordinate order was: men > pre-MP women > post-MP women. After fat adjustment of the BMC, order in both limbs was: men > pre-MP women > post-MP women. Parallelism of the curves was maintained in all cases. LM had a larger independent influence on these results than FM, body weight, or age. The parallelism of the curves supports the idea that a common biomechanical control of bones by muscles occurs in humans. Results suggest that sex-hormone-associated differences in DXA-assessed muscle-bone proportionality in humans could vary according to the region studied. This could be related to the different weight-bearing nature of the musculoskeletal structures studied. Besides the obvious anthropometric associations, FM would exert a mechanical effect as a component of body weight, evident in the lower limbs, while

  13. Correspondence between theoretical models and dual energy x-ray absorptiometry measurements of femoral cross-sectional growth during adolescence.

    PubMed

    van der Meulen, M C; Marcus, R; Bachrach, L K; Carter, D R

    1997-05-01

    We have developed an analytical model of long bone cross-sectional ontogeny in which appositional growth of the diaphysis is primarily driven by mechanical stimuli associated with increasing body mass during growth and development. In this study, our goal was to compare theoretical predictions of femoral diaphyseal structure from this model with measurements of femoral bone mineral and geometry by dual energy x-ray absorptiometry. Measurements of mid-diaphyseal femoral geometry and structure were made previously in 101 Caucasian adolescents and young adults 9-26 years of age. The data on measured bone mineral content and calculated section modulus were compared with the results of our analytical model of cross-sectional development of the human femur over the same age range. Both bone mineral content and section modulus showed good correspondence with experimental measurements when the relationships with age and body mass were examined. Strong linear relationships were evident for both parameters when examined as a function of body mass.

  14. Dual-photon absorptiometry: Comparison of bone mineral and soft tissue mass measurements in vivo with established methods

    SciTech Connect

    Heymsfield, S.B.; Wang, J.; Heshka, S.; Kehayias, J.J.; Pierson, R.N.

    1989-06-01

    This study extended initial observations that indicated the potential of dual-photon absorptiometry (DPA) to measure total-body bone mineral (TBBM) and fat in vivo. DPA-derived TBBM and fat were compared with established methods in 13 subjects (aged 24-94 y) who underwent measurement of body density (Db), total-body water (TBW), potassium (TBK), calcium (TBCa, delayed-gamma neutron activation), and nitrogen (prompt-gamma neutron activation). TBBM was highly correlated with TBCa (r = 0.95, p less than 0.001) and the slope of TBCa vs TBBM (0.34) was similar to Ca content of ashed skeleton (0.34-0.38). DPA-measured fat (means +/- SD, 16.7 +/- 4.9 kg) correlated significantly (r = 0.79-0.94; p less than 0.01-0.001) with fat established by Db (16.3 +/- 5.4 kg), TBW (16.0 +/- 4.3 kg), TBK (17.7 +/- 4.6 kg), combined TBW-neutron activation (17.6 +/- 5.9 kg), and means of all four methods (16.9 +/- 4.8 kg). DPA thus offers a new opportunity to study human skeleton in vivo and to quantify fat by a method independent from the classical assumption that bone represents a fixed fraction of fat-free body mass.

  15. Quick benefits of interval training versus continuous training on bone: a dual-energy X-ray absorptiometry comparative study.

    PubMed

    Boudenot, Arnaud; Maurel, Delphine B; Pallu, Stéphane; Ingrand, Isabelle; Boisseau, Nathalie; Jaffré, Christelle; Portier, Hugues

    2015-12-01

    To delay age-related bone loss, physical activity is recommended during growth. However, it is unknown whether interval training is more efficient than continuous training to increase bone mass both quickly and to a greater extent. The aim of this study was to compare the effects of a 10-week interval training regime with a 14-week continuous training regime on bone mineral density (BMD). Forty-four male Wistar rats (8 weeks old) were separated into four groups: control for 10 weeks (C10), control for 14 weeks (C14), moderate interval training for 10 weeks (IT) and moderate continuous training for 14 weeks (CT). Rats were exercised 1 h/day, 5 day/week. Body composition and BMD of the whole body and femur respectively were assessed by dual-energy X-ray absorptiometry at baseline and after training to determine raw gain and weight-normalized BMD gain. Both trained groups had lower weight and fat mass gain when compared to controls. Both trained groups gained more BMD compared to controls when normalized to body weight. Using a 30% shorter training period, the IT group showed more than 20% higher whole body and femur BMD gains compared to the CT. Our data suggest that moderate IT was able to produce faster bone adaptations than moderate CT.

  16. Quantitative computed tomographic evaluation of femoral bone mineral content in renal osteodystrophy compared with radial photon absorptiometry

    SciTech Connect

    Sakurai, K.; Marumo, F.; Iwanami, S.; Uchida, H.; Matsubayashi, T.

    1989-05-01

    The computed tomography (CT) numbers of cortical bone at the level of 20 cm (CT20) and of spongiosa in the lateral condyle at the level of 2 cm (CT02) from the distal end of the femur were obtained by a quantitative CT method and compared with the bone mineral density of mostly cortical bone within the radius (BMD) by photon absorptiometry. The study included 47 patients with chronic renal failure not dialyzed or induced to regular hemodialysis within 4 weeks of the study (group 1), 28 patients on regular hemodialysis for more than one month (group 2), and ten healthy volunteers (group 3). The measures of bone mineral content (BMC), namely CT20, CT02, and BMD, were compared in terms of their abilities to distinguish members in the various groups. For group 1 and group 3, the greatest variation in BMC was in the difference in CT02, which was primarily a measurement of the BMC of spongiosa. For groups 1 and 2, the greatest variation was in the difference in BMD, which was primarily a measurement of the BMC of cortex. The reproducibility of CT02 was estimated as almost equal to the difference in CT02 values at intervals of 10 months' duration of hemodialysis. The results indicated that CT02 was a useful measurement for evaluating the progress in the early stage of the renal osteodystrophy, and it is recommended that the bone mineral measurement with this QCT method should be performed once or twice a year.

  17. Correspondence between theoretical models and dual energy x-ray absorptiometry measurements of femoral cross-sectional growth during adolescence

    NASA Technical Reports Server (NTRS)

    van der Meulen, M. C.; Marcus, R.; Bachrach, L. K.; Carter, D. R.

    1997-01-01

    We have developed an analytical model of long bone cross-sectional ontogeny in which appositional growth of the diaphysis is primarily driven by mechanical stimuli associated with increasing body mass during growth and development. In this study, our goal was to compare theoretical predictions of femoral diaphyseal structure from this model with measurements of femoral bone mineral and geometry by dual energy x-ray absorptiometry. Measurements of mid-diaphyseal femoral geometry and structure were made previously in 101 Caucasian adolescents and young adults 9-26 years of age. The data on measured bone mineral content and calculated section modulus were compared with the results of our analytical model of cross-sectional development of the human femur over the same age range. Both bone mineral content and section modulus showed good correspondence with experimental measurements when the relationships with age and body mass were examined. Strong linear relationships were evident for both parameters when examined as a function of body mass.

  18. Magnetic resonance imaging and dual energy X-ray absorptiometry of the lumbar spine in professional wrestlers and untrained men.

    PubMed

    Hu, M; Sheng, J; Kang, Z; Zou, L; Guo, J; Sun, P

    2014-08-01

    The aim of this study was to examine the relation between bone marrow adipose tissue (BMAT) and bone mineral density (BMD) of lumbar spine in male professional wrestlers and healthy untrained men. A total of 14 wrestlers (22.9±3.4 years) and 11 controls (24.4±1.6 years) were studied cross-sectionally. Body composition and BMD were measured by dual-energy X-ray absorptiometry. Magnetic resonance imaging of the lumbar spine was examined in a sagittal T1-weighted (T1-w) spin-echo (SE) sequence. The averaged bone marrow signal intensity (SI) of L2-L4 was related to the signal of an adjacent nondegenerative disk. Mean SI of T1-w SE in wrestlers was lower than controls (P=0.001), indicating L2-L4 BMAT in wrestlers was lower compared to controls. L2-L4 BMD in wrestlers was higher than controls (P<0.001). In the total subject population, L2-L4 BMD was inversely correlated with mean SI of T1-w SE (r=-0.62, P=0.001). This association remained strong after adjusting for body mass and whole lean mass, but became weaker after adjusting for whole body or trunk fat percentage. The inverse relationship between BMAT and BMD was confirmed in this relatively small subject sample with narrow age range, which implies that exercise training is an important determinant of this association.

  19. Magnetic resonance imaging of the calcaneus: preliminary assessment of trabecular bone-dependent regional variations in marrow relaxation time compared with dual X-ray absorptiometry

    NASA Technical Reports Server (NTRS)

    Guglielmi, G.; Selby, K.; Blunt, B. A.; Jergas, M.; Newitt, D. C.; Genant, H. K.; Majumdar, S.

    1996-01-01

    RATIONALE AND OBJECTIVES: Marrow transverse relaxation time (T2*) in magnetic resonance (MR) imaging may be related to the density and structure of the surrounding trabecular network. We investigated regional variations of T2* in the human calcaneus and compared the findings with bone mineral density (BMD), as measured by dual X-ray absorpiometry (DXA). Short- and long-term precisions were evaluated first to determine whether MR imaging would be useful for the clinical assessment of disease status and progression in osteoporosis. METHODS: Gradient-recalled echo MR images of the calcaneus were acquired at 1.5 T from six volunteers. Measurements of T2* were compared with BMD and (for one volunteer) conventional radiography. RESULTS: T2* values showed significant regional variation; they typically were shortest in the superior region of the calcaneus. There was a linear correlation between MR and DXA measurements (r = .66 for 1/T2* versus BMD). Differences in T2* attributable to variations in analysis region-of-interest placement were not significant for five of the six volunteers. Sagittal MR images had short- and long-term precision errors of 4.2% and 3.3%, respectively. For DXA, the precision was 1.3% (coefficient of variation). CONCLUSION: MR imaging may be useful for trabecular bone assessment in the calcaneus. However, given the large regional variations in bone density and structure, the choice of an ROI is likely to play a major role in the accuracy, precision, and overall clinical efficacy of T2* measurements.

  20. Digital X-ray radiogrammetry in the study of osteoporotic fractures: Comparison to dual energy X-ray absorptiometry and FRAX.

    PubMed

    Kälvesten, Johan; Lui, Li-Yung; Brismar, Torkel; Cummings, Steven

    2016-05-01

    Osteoporosis is often underdiagnosed and undertreated. Screening of post-menopausal women for clinical risk factors and/or low bone mineral density (BMD) has been proposed to overcome this. Digital X-ray radiogrammetry (DXR) estimates hand BMD from standard hand X-ray images and have shown to predict fractures and osteoporosis. Recently, digital radiology and the internet have opened up the possibility of conducting automated opportunistic screening with DXR in post-fracture care or in combination with mammography. This study compared the performance of DXR with FRAX® and DXA in discriminating major osteoporotic fracture (MOF) (hip, clinical spine, forearm or shoulder), hip fracture and femoral neck osteoporosis. This prospective cohort study was conducted on 5278 women 65years and older in the Study of Osteoporotic Fractures (SOF) cohort. Baseline hand X-ray images were analyzed and fractures were ascertained during 10years of follow up. Age-adjusted area under receiver operating characteristic curve (AUC) for MOF and hip fracture and for femoral neck osteoporosis (DXA FN BMD T-score ≤-2.5) was used to compare the methods. Sensitivity to femoral neck osteoporosis at equal selection rates was tabulated for FRAX and DXR. DXR-BMD, FRAX (no BMD) and lumbar spine DXA BMD were all similar in fracture discriminative performance with an AUC around 0.65 for MOF and 0.70 for hip fractures for all three methods. As expected femoral neck DXA provided fracture discrimination superior both to other BMD measurements and to FRAX. AUC for selection of patients with femoral neck osteoporosis was higher with DXR-BMD, 0.76 (0.74-0.77), than with FRAX, 0.69 (0.67-0.71), (p<0.0001). In conclusion, DXR-BMD discriminates incident fractures to a similar degree as FRAX and predicts femoral neck osteoporosis to a larger degree than FRAX. DXR shows promise as a method to automatically flag individuals who might benefit from an osteoporosis assessment. PMID:26921822

  1. Body composition in neonates: relationship between measured and derived anthropometry with dual-energy X-ray absorptiometry measurements.

    PubMed

    Koo, Winston W K; Walters, Jocelyn C; Hockman, Elaine M

    2004-11-01

    This study examined the relationship between measured and derived anthropometric measurements with dual-energy X-ray absorptiometry measured lean and fat mass at 3.0 +/- 2.8 (SD) days in 120 neonates with birth weights appropriate (AGA; n=74), large (LGA; n=30); or small (SGA, n=16) for gestational age. Anthropometric measurements, including total body weight and length, and regional measurements, including circumferences of head, chest, abdomen, midarm, and midthigh and dynamic skinfold thickness (15 and 60 s) at tricep, subscapular, suprailiac, and midthigh, were performed. Derived anthropometry included muscle and fat areas, and ratios were calculated from direct measurements. The skinfold thickness measurements between 15 and 60 s were highly correlated (r=0.973-0.996, p <0.001 for all comparisons). Strong correlations existed within the four circumferences of trunk and extremities, the four skinfolds, and the ratios of weight to length and its higher powers. Weight and length accounted for >97% of the variance of lean mass in AGA and SGA infants and 46% of the variance in LGA infants and for 80, 82, and 84% of the variance of fat mass in SGA, AGA, and LGA infants, respectively, whereas midarm:head circumference ratio and arm muscle and fat areas are the most important derived anthropometry in the prediction for body composition. They independently accounted for up to 16.5 and 10.2%, respectively, of the variance in body composition depending on the state of in utero growth. Thus, total body weight and length and some selected regional and derived anthropometry accounted for the vast majority of the variance of body composition. PMID:15371563

  2. Effects of Exemestane and Tamoxifen treatment on bone texture analysis assessed by TBS in comparison with bone mineral density assessed by DXA in women with breast cancer.

    PubMed

    Kalder, Matthias; Hans, Didier; Kyvernitakis, Ioannis; Lamy, Olivier; Bauer, Martina; Hadji, Peyman

    2014-01-01

    We performed an analysis of a substudy of the randomized Tamoxifen Exemestane Adjuvant Multinational trial to determine the effects of exemestane (EXE) and tamoxifen (TAM) adjuvant treatment on bone mineral density (BMD) measured by dual-energy X-ray absorptiometry compared with the trabecular bone score, a novel grey-level texture measurement that correlates with 3-dimensional parameters of bone texture in postmenopausal women with hormone receptor-positive breast cancer for the first time. In total, 36 women were randomized to receive TAM (n = 17) or EXE (n = 19). Patients receiving TAM showed a mean increase of BMD in lumbar spine from baseline of 1.0%, 1.5%, and 1.9% and in trabecular bone score of 2.2%, 3.5%, and 3.3% at 6-, 12-, and 24-mo treatment, respectively. Conversely, patients receiving EXE showed a mean decrease from baseline in lumbar spine BMD of -2.3%, -3.6%, and -5.3% and in trabecular bone score of -0.9%, -1.7%, and -2.3% at 6-, 12-, and 24-mo treatment, respectively. Changes in trabecular bone score from baseline at spine were also significantly different between EXE and TAM: p = 0.05, 0.007, and 0.006 at 6, 12, and 24 mo, respectively. TAM induced an increase in BMD and bone texture analysis, whereas EXE resulted in decreases. The results were independent from each other.

  3. Abdominal CT scan

    MedlinePlus

    Computed tomography scan - abdomen; CT scan - abdomen; CT abdomen and pelvis ... 2016:chap 133. Radiologyinfo.org. Computed tomography (CT) - abdomen and pelvis. Updated June 16, 2016. www.radiologyinfo. ...

  4. RBC nuclear scan

    MedlinePlus

    ... page: //medlineplus.gov/ency/article/003835.htm RBC nuclear scan To use the sharing features on this page, please enable JavaScript. An RBC nuclear scan uses small amounts of radioactive material to ...

  5. Experimental studies on the bone metabolism of male rats chronically exposed to cadmium intoxication using dual-energy X-ray absorptiometry.

    PubMed

    Yokota, H; Tonami, H

    2008-04-01

    Cadmium (Cd) has been identified as the etiologic agent of itai-itai disease. The purpose of this study was to investigate whether chronic Cd exposure affects bone metabolism in a male rat model and to estimate the bone mineral density (BMD) differences in lumbar and femoral bone because of Cd exposure. Six-week-old male Hos Donryu rats were used in this experiment. Cadmium was administered at a dose of 200 ppm to rats in the diet to produce experimental chronic Cd poisoning. Bone mineral density was measured using dual-energy X-ray absorptiometry (DEXA) with a high-resolution scan collimator (0.25 mm diameter) (Hologic QDR-2000). The Cd content in renal tissue reached a critical concentration of 128.42 +/- 14.38 microg/g 10 months after the administration of the element (Table 3). The average blood urea nitrogen (BUN) value was increased throughout the period of the experiment, and the serum creatinine value of the experimental group showed an increase after 2 months of Cd administration (0.46 +/- 0.09 mg/dL). The concentration of urinary calcium changed in the experimental group after exposure to Cd for 12 months (15.4 +/- 0.13 mg/dL). DEXA showed a greater reduction in the bone mineral density of the 5th vertebral body (L5) in rats that had ingested Cd for 4 months (0.359 +/- 0.013 g/cm2) than in control rats (0.372 +/- 0.012 g/cm2, P < 0.01). On the contrary, the difference in bone mineral content between rats ingesting Cd for 6-8 months and control rats was not significant. However, significant reductions in bone mineral content were again noted in rats that had ingested Cd for 12 months (0.339 +/- 0.023 g/cm2) compared with the control group (0.385 +/- 0.012 g/cm2, P < 0.01). The bone mineral density of the right femoral bone in control rats was 0.328 +/- 0.018 g/cm2 and that in experimental rats was 0.306 +/- 0.012 g/cm2, and a meaningful difference was recognized (P < 0.05). Histological examination of the rats exposed to Cd for 12 months showed that the 5

  6. Scanning Seismic Intrusion Detector

    NASA Technical Reports Server (NTRS)

    Lee, R. D.

    1982-01-01

    Scanning seismic intrusion detector employs array of automatically or manually scanned sensors to determine approximate location of intruder. Automatic-scanning feature enables one operator to tend system of many sensors. Typical sensors used with new system are moving-coil seismic pickups. Detector finds uses in industrial security systems.

  7. Multipurpose binocular scanning apparatus

    NASA Technical Reports Server (NTRS)

    Chamberlain, F. R.; Parker, G. L.

    1969-01-01

    Optical gimballing apparatus directs narrow fields of view throughout solid angle approaching 4 pi steradians. Image rotation produced by scanning can be eliminated or altered by gear trains directly linked to the scanning drive assembly. It provides the basis for a binocular scanning capability.

  8. Pulmonary ventilation/perfusion scan

    MedlinePlus

    V/Q scan; Ventilation/perfusion scan; Lung ventilation/perfusion scan ... A pulmonary ventilation/perfusion scan is actually two tests. They may be done separately or together. During the perfusion scan, a health care ...

  9. Line-scanning, stage scanning confocal microscope

    NASA Astrophysics Data System (ADS)

    Carucci, John A.; Stevenson, Mary; Gareau, Daniel

    2016-03-01

    We created a line-scanning, stage scanning confocal microscope as part of a new procedure: video assisted micrographic surgery (VAMS). The need for rapid pathological assessment of the tissue on the surface of skin excisions very large since there are 3.5 million new skin cancers diagnosed annually in the United States. The new design presented here is a confocal microscope without any scanning optics. Instead, a line is focused in space and the sample, which is flattened, is physically translated such that the line scans across its face in a direction perpendicular to the line its self. The line is 6mm long and the stage is capable of scanning 50 mm, hence the field of view is quite large. The theoretical diffraction-limited resolution is 0.7um lateral and 3.7um axial. However, in this preliminary report, we present initial results that are a factor of 5-7 poorer in resolution. The results are encouraging because they demonstrate that the linear array detector measures sufficient signal from fluorescently labeled tissue and also demonstrate the large field of view achievable with VAMS.

  10. MRI-measured pelvic bone marrow adipose tissue is inversely related to DXA-measured bone mineral in younger and older Adults

    PubMed Central

    Shen, Wei; Chen, Jun; Gantz, Madeleine; Punyanitya, Mark; Heymsfield, Steven B; Gallagher, Dympna; Albu, Jeanine; Engelson, Ellen; Kotler, Donald; Pi-Sunyer, Xavier; Gilsanz, Vicente

    2012-01-01

    Background/Objective Recent research has shown an inverse relationship between bone marrow adipose tissue (BMAT) and bone mineral density (BMD). There is a lack of evidence at the macro-imaging level to establish whether increased BMAT is a cause or effect of bone loss. This cross-sectional study compared the BMAT and BMD relationship between a younger adult group at or approaching peak bone mass (PBM) (age 18.0-39.9 yrs) and an older group with potential bone loss (PoBL) (age 40.0-88 yrs). Subjects/Methods Pelvic BMAT was evaluated in 560 healthy men and women with T1-weighted whole body magnetic resonance imaging. BMD was measured using whole body dual-energy x-ray absorptiometry. Results An inverse correlation was observed between pelvic BMAT and pelvic, total, and spine BMD in the younger PBM group (r=-0.419 to -0.461, P<0.001) and in the older PoBL group (r=-0.405 to -0.500, P<0.001). After adjusting for age, sex, ethnicity, menopausal status, total body fat, skeletal muscle, subcutaneous and visceral adipose tissue, neither subject group (younger PBM vs. older PoBL) nor its interaction with pelvic BMAT significantly contributed to the regression models with BMD as dependent variable and pelvic BMAT as independent variable (P=0.434 to 0.928). Conclusion Our findings indicate that an inverse relationship between pelvic BMAT and BMD is present both in younger subjects who have not yet experienced bone loss and also in older subjects. These results provide support at the macro-imaging level for the hypothesis that low BMD may be a result of preferential differentiation of mesenchymal stem cells from osteoblasts to adipocytes. PMID:22491495

  11. Skeletal status and soft tissue composition in astronauts. Tissue and fluid changes by radionuclide absorptiometry in vivo

    NASA Technical Reports Server (NTRS)

    Cameron, J. R.; Mazess, R. B.; Wilson, C. R.

    1973-01-01

    A device has been constructed and tested which provides immediate readout of bone mineral content and bone width from absorptiometric scans with low energy radionuclides. The basis of this analog system is a logarithmic converter-integrator coupled with a precision linear ratemeter. The system provided accurate and reliable results on standards and ashed bone sections. Clinical measurements were made on about 100 patients with the direct readout system, and these were highly correlated with the results from digital scan data on the same patients. The direct readout system has been used successfully in field studies and surveys as well as for clinical observations.

  12. Getting a CAT Scan

    MedlinePlus

    ... Here's Help White House Lunch Recipes Getting a CAT Scan (Video) KidsHealth > For Kids > Getting a CAT Scan (Video) A A A en español Obtención de una tomografía computada (video) CAT stands for "computerized axial tomography." Translated, that means ...

  13. Optical Scanning Applications.

    ERIC Educational Resources Information Center

    Wagner, Hans

    The successful use of optical scanning at the University of the Pacific (UOP) indicates that such techniques can simplify a number of administrative data processing tasks. Optical scanning is regularly used at UOP to assist with data processing in the areas of admissions, registration and grade reporting and also has applications for other tasks…

  14. Multiline radar scan

    NASA Technical Reports Server (NTRS)

    Levinson, S.

    1977-01-01

    Scanning scheme is more efficient than conventional scanning. Originally designed for optical radar in space vehicles, scheme may also find uses in site-surveillance security systems and in other industrial applications. It should be particularly useful when system must run on battery energy, as would be case in power outages.

  15. Virtual slit scanning microscopy.

    PubMed

    Fiolka, Reto; Stemmer, Andreas; Belyaev, Yury

    2007-12-01

    We present a novel slit scanning confocal microscope with a CCD camera image sensor and a virtual slit aperture for descanning that can be adjusted during post-processing. A very efficient data structure and mathematical criteria for aligning the virtual aperture guarantee the ease of use. We further introduce a method to reduce the anisotropic lateral resolution of slit scanning microscopes. System performance is evaluated against a spinning disk confocal microscope on identical specimens. The virtual slit scanning microscope works as the spinning disk type and outperforms on thick specimens. PMID:17891411

  16. The Scanning Optical Microscope.

    ERIC Educational Resources Information Center

    Sheppard, C. J. R.

    1978-01-01

    Describes the principle of the scanning optical microscope and explains its advantages over the conventional microscope in the improvement of resolution and contrast, as well as the possibility of producing a picture from optical harmonies generated within the specimen.

  17. Leg MRI scan

    MedlinePlus

    ... resonance imaging) scan of the leg uses strong magnets to create pictures of the leg. This may ... in your eyes) Because the MRI contains strong magnets, metal objects are not allowed into the room ...

  18. Slow Scan Telemedicine

    NASA Technical Reports Server (NTRS)

    1984-01-01

    Originally developed under contract for NASA by Ball Bros. Research Corporation for acquiring visual information from lunar and planetary spacecraft, system uses standard closed circuit camera connected to a device called a scan converter, which slows the stream of images to match an audio circuit, such as a telephone line. Transmitted to its destination, the image is reconverted by another scan converter and displayed on a monitor. In addition to assist scans, technique allows transmission of x-rays, nuclear scans, ultrasonic imagery, thermograms, electrocardiograms or live views of patient. Also allows conferencing and consultation among medical centers, general practitioners, specialists and disease control centers. Commercialized by Colorado Video, Inc., major employment is in business and industry for teleconferencing, cable TV news, transmission of scientific/engineering data, security, information retrieval, insurance claim adjustment, instructional programs, and remote viewing of advertising layouts, real estate, construction sites or products.

  19. Pediatric CT Scans

    Cancer.gov

    The Radiation Epidemiology Branch and collaborators have initiated a retrospective cohort study to evaluate the relationship between radiation exposure from CT scans conducted during childhood and adolescence and the subsequent development of cancer.

  20. Fiber-Scanned Microdisplays

    NASA Technical Reports Server (NTRS)

    Crossman-Bosworth, Janet; Seibel, Eric

    2010-01-01

    Helmet- and head-mounted display systems, denoted fiber-scanned microdisplays, have been proposed to provide information in an "augmented reality" format (meaning that the information would be optically overlaid on the user's field of view).

  1. Brain PET scan

    MedlinePlus

    ... tests, such as magnetic resonance imaging ( MRI ) and computed tomography ( CT ) scans only reveal the structure of the ... a PET/CT. Alternative Names ... PT, Rijntjes M, Weiller C. Neuroimaging: Functional neuroimaging. In: Daroff RB, Fenichel GM, Jankovic ...

  2. The conical scan radiometer

    NASA Astrophysics Data System (ADS)

    Prosch, T.; Hennings, D.

    1982-07-01

    A satellite-borne conical scan radiometer (CSR) is proposed, offering multiangular and multispectral measurements of Earth radiation fields, including the total radiances, which are not available from conventional radiometers. Advantages of the CSR for meteorological studies are discussed. In comparison to conventional cross track scanning instruments, the CSR is unique with respect to the selected picture element size which is kept constant by means of a specially shaped detector matrix at all scan angles. The conical scan mode offers the chance to improve angular sampling. Angular sampling gaps of previous satellite-borne radiometers can be interpolated and complemented by CSR data. Radiances are measured through 10 radiometric channels which are selected to study cloudiness, water vapor, ozone, surface albedo, ground and mean stratospheric temperature, and aerosols.

  3. Scanning Mueller polarimetric microscopy.

    PubMed

    Le Gratiet, Aymeric; Dubreuil, Matthieu; Rivet, Sylvain; Le Grand, Yann

    2016-09-15

    A full Mueller polarimeter was implemented on a commercial laser-scanning microscope. The new polarimetric microscope is based on high-speed polarization modulation by spectral coding using a wavelength-swept laser as a source. Calibration as well as estimation of the measurement errors of the device are reported. The acquisition of Mueller images at the speed of a scanning microscope is demonstrated for the first time. Mueller images of mineral and biological samples illustrate this new polarimetric microscopy. PMID:27628391

  4. Wide scanning spherical antenna

    NASA Technical Reports Server (NTRS)

    Shen, Bing (Inventor); Stutzman, Warren L. (Inventor)

    1995-01-01

    A novel method for calculating the surface shapes for subreflectors in a suboptic assembly of a tri-reflector spherical antenna system is introduced, modeled from a generalization of Galindo-Israel's method of solving partial differential equations to correct for spherical aberration and provide uniform feed to aperture mapping. In a first embodiment, the suboptic assembly moves as a single unit to achieve scan while the main reflector remains stationary. A feed horn is tilted during scan to maintain the illuminated area on the main spherical reflector fixed throughout the scan thereby eliminating the need to oversize the main spherical reflector. In an alternate embodiment, both the main spherical reflector and the suboptic assembly are fixed. A flat mirror is used to create a virtual image of the suboptic assembly. Scan is achieved by rotating the mirror about the spherical center of the main reflector. The feed horn is tilted during scan to maintain the illuminated area on the main spherical reflector fixed throughout the scan.

  5. Comparison of Methods for Assessing Body Composition Changes during Weight Loss.

    ERIC Educational Resources Information Center

    Weyers, Anna M.; Mazzetti, Scott A.; Love, Dawn M.; Gomez, Ana L.; Kraemer, William J.; Volek, Jeff S.

    2002-01-01

    Investigated whether dual-energy x-ray absorptiometry (DXA) and air displacement plethysmography (ADP) would detect similar changes in body composition after moderate weight loss. Twenty adults had their body composition measured using DXA and ADP before and after an 8-week weight loss program. Overall, both DXA and ADP detected similar changes in…

  6. Dual-energy X-ray performs as well as clinical computed tomography for the measurement of visceral fat.

    PubMed

    Micklesfield, Lisa K; Goedecke, Julia H; Punyanitya, Mark; Wilson, Kevin E; Kelly, Thomas L

    2012-05-01

    Visceral adipose tissue (VAT) is associated with adverse health effects including cardiovascular disease and type 2 diabetes. We developed a dual-energy X-ray absorptiometry (DXA) measurement of visceral adipose tissue (DXA-VAT) as a low cost and low radiation alternative to computed tomography (CT). DXA-VAT was compared to VAT assessed using CT by an expert reader (E-VAT). In addition, the same CT slice was also read by a clinical radiographer (C-VAT) and a best-fit anthropomorphic and demographic VAT model (A-VAT) was developed. Whole body DXA, CT at L4-L5, and anthropometry were measured on 272 black and white South African women (age 29 ± 8 years, BMI 28 ± 7 kg/m(2), waist circumference (WC) 89 ± 16 cm). Approximately one-half of the dataset (n = 141) was randomly selected and used as a training set for the development of DXA-VAT and A-VAT, which were then used to estimate VAT on the remaining 131 women in a blinded fashion. DXA-VAT (r = 0.93, standard error of the estimate (SEE) = 16 cm(2)) and C-VAT (r = 0.93, SEE = 16 cm(2)) were strongly correlated to E-VAT. These correlations with E-VAT were significantly stronger (P < 0.001) than the correlations of individual anthropometry measurements and the A-VAT model (WC + age, r = 0.79, SEE = 27 cm(2)). The inclusion of anthropometric and demographic measurements did not substantially improve the correlation between DXA-VAT and E-VAT. DXA-VAT performed as well as a clinical read of VAT from a CT scan and better than anthropomorphic and demographic models. PMID:22240726

  7. [Laser scanning in ophthalmology].

    PubMed

    Jean, B; Frohn, A; Thiel, H J

    1990-01-01

    The current state of the art for the major laser scanning methods, laser scanning ophthalmoscopy (LSO) and laser tomographic scanning (LTS) is discussed and the function principles are described. Experience with a prototype of each instrument from Rodenstock (LSO) and Heidelberg Instruments (LTS) is reported. LSO imaging of the cornea, vitreous, retina, and optic disc, as well as on-line processing is demonstrated with examples (nerve fibre colour coding and histograms). Measurement of the cornea, optic disc and retinal topography with LTS is also demonstrated with examples. An example of polarization optical imaging of the cornea's assumed interferometric "tension patterns" is shown. The current status and future possibilities of laser scanning, its expanded diagnostic potential with microperimetry, IR scanning angiography and polarization optic imaging and measurement (eg. nerve fibre thickness) is discussed extensively. The safety aspects of laser light exposure of the macula are also mentioned. Laser scanners as imaging and measuring sensors of unknown accuracy open a new area of possibly revolutionary diagnostic possibilities.

  8. [In vivo measurement of the mineral content of renal calculi by dual-photon absorptiometry. Correlation with its fragility to extracorporeal shockwave lithotripsy].

    PubMed

    Zanchetta, J R; Bogado, C E; Sánchez, T V; Gigler, C; Ghirlanda, J

    1995-01-01

    After a few years of experience with extracorporeal shock wave lithotripsy (ESWL) and other fragmentation techniques, it has become apparent that stone fragility is a significant clinical distinction that should be taken into consideration when selecting a treatment program. In 30 unselected patients, stone mineral content, density and area were measured in vivo by dual-photon absorptiometry prior to perform ESWL treatment. Stone area determinations showed a median of 4.21 with a range of 0.46 to 49.7 cm2. Stone mineral content (g) and stone density (g/cm2) values were 2.47 and 0.46 with ranges of 0.37 to 13.7 and 0.167 to 1.203 respectively. The number of shocks needed for total fragmentation were 2375 with a range of 1200 to 7800. No correlation could be found between the number of shocks needed for fragmentation and the stone area or density. On the other hand, a strong linear correlation (r = 0.81, p < 0.001) (Fig. 1) could be demonstrated between stone mineral content and the number of shocks needed for fragmentation. Our results support the concept that size alone is not always a suitable criterion for selecting a stone as appropiate for ESWL, since no correlation could be found between stone area and the number of shocks needed for total fragmentation. We were also unable to find any correlation between in vivo stone density measured by dual-photon absorptiometry and the number of shocks required for stone fragmentation. Instead, a strong linear correlation between stone mineral content and its resistance to shock wave fragmentation was found. Therefore, calculation of mineral content appears to be the determinant of the amount of energy required for total fragmentation. Our results strongly suggest that in vivo stone mineral content measurement provides helpful information for predicting the fragmentation prospect of a stone.

  9. Vector generator scan converter

    DOEpatents

    Moore, J.M.; Leighton, J.F.

    1988-02-05

    High printing speeds for graphics data are achieved with a laser printer by transmitting compressed graphics data from a main processor over an I/O channel to a vector generator scan converter which reconstructs a full graphics image for input to the laser printer through a raster data input port. The vector generator scan converter includes a microprocessor with associated microcode memory containing a microcode instruction set, a working memory for storing compressed data, vector generator hardware for drawing a full graphic image from vector parameters calculated by the microprocessor, image buffer memory for storing the reconstructed graphics image and an output scanner for reading the graphics image data and inputting the data to the printer. The vector generator scan converter eliminates the bottleneck created by the I/O channel for transmitting graphics data from the main processor to the laser printer, and increases printer speed up to thirty fold. 7 figs.

  10. Vector generator scan converter

    DOEpatents

    Moore, James M.; Leighton, James F.

    1990-01-01

    High printing speeds for graphics data are achieved with a laser printer by transmitting compressed graphics data from a main processor over an I/O (input/output) channel to a vector generator scan converter which reconstructs a full graphics image for input to the laser printer through a raster data input port. The vector generator scan converter includes a microprocessor with associated microcode memory containing a microcode instruction set, a working memory for storing compressed data, vector generator hardward for drawing a full graphic image from vector parameters calculated by the microprocessor, image buffer memory for storing the reconstructed graphics image and an output scanner for reading the graphics image data and inputting the data to the printer. The vector generator scan converter eliminates the bottleneck created by the I/O channel for transmitting graphics data from the main processor to the laser printer, and increases printer speed up to thirty fold.

  11. Vector generator scan converter

    SciTech Connect

    Moore, J.M.; Leighton, J.F.

    1990-04-17

    This patent describes high printing speeds for graphics data that are achieved with a laser printer by transmitting compressed graphics data from a main processor over an I/O (input/output) channel to a vector generator scan converter which reconstructs a full graphics image for input to the laser printer through a raster data input port. The vector generator scan converter includes a microprocessor with associated microcode memory containing a microcode instruction set, a working memory for storing compressed data, vector generator hardware for drawing a full graphic image from vector parameters calculated by the microprocessor, image buffer memory for storing the reconstructed graphics image and an output scanner for reading the graphics image data and inputting the data to the printer. The vector generator scan converter eliminates the bottleneck created by the I/O channel for transmitting graphics data from the main processor to the laser printer, and increases printer speed up to thirty fold.

  12. Adaptive Optical Scanning Holography

    PubMed Central

    Tsang, P. W. M.; Poon, Ting-Chung; Liu, J.-P.

    2016-01-01

    Optical Scanning Holography (OSH) is a powerful technique that employs a single-pixel sensor and a row-by-row scanning mechanism to capture the hologram of a wide-view, three-dimensional object. However, the time required to acquire a hologram with OSH is rather lengthy. In this paper, we propose an enhanced framework, which is referred to as Adaptive OSH (AOSH), to shorten the holographic recording process. We have demonstrated that the AOSH method is capable of decreasing the acquisition time by up to an order of magnitude, while preserving the content of the hologram favorably. PMID:26916866

  13. Tomographic scanning imager.

    PubMed

    Hovland, Harald

    2009-07-01

    In tomographic scanning (TOSCA) imaging, light from a scene is focused onto a reticle mask using conical scan optics, and collected on a single element detector. Alternatively, one or several detectors replace the reticle. Tomographic processing techniques are then applied to the one-dimensional signal to reproduce a two-dimensional image. The TOSCA technique is presented in detail, including its mathematical foundations and some of its limitations. It is shown how TOSCA imaging can be used in a multispectral configuration, and compares well with more conventional alternatives both in simplicity and performance. Examples of image reconstruction using TOSCA techniques are shown. PMID:19582052

  14. Scanning computed confocal imager

    DOEpatents

    George, John S.

    2000-03-14

    There is provided a confocal imager comprising a light source emitting a light, with a light modulator in optical communication with the light source for varying the spatial and temporal pattern of the light. A beam splitter receives the scanned light and direct the scanned light onto a target and pass light reflected from the target to a video capturing device for receiving the reflected light and transferring a digital image of the reflected light to a computer for creating a virtual aperture and outputting the digital image. In a transmissive mode of operation the invention omits the beam splitter means and captures light passed through the target.

  15. Ultrafast scanning probe microscopy

    DOEpatents

    Weiss, Shimon; Chemla, Daniel S.; Ogletree, D. Frank; Botkin, David

    1995-01-01

    An ultrafast scanning probe microscopy method for achieving subpicosecond-temporal resolution and submicron-spatial resolution of an observation sample. In one embodiment of the present claimed invention, a single short optical pulse is generated and is split into first and second pulses. One of the pulses is delayed using variable time delay means. The first pulse is then directed at an observation sample located proximate to the probe of a scanning probe microscope. The scanning probe microscope produces probe-sample signals indicative of the response of the probe to characteristics of the sample. The second pulse is used to modulate the probe of the scanning probe microscope. The time delay between the first and second pulses is then varied. The probe-sample response signal is recorded at each of the various time delays created between the first and second pulses. The probe-sample response signal is then plotted as a function of time delay to produce a cross-correlation of the probe sample response. In so doing, the present invention provides simultaneous subpicosecond-temporal resolution and submicron-spatial resolution of the sample.

  16. Ultrafast scanning probe microscopy

    DOEpatents

    Weiss, S.; Chemla, D.S.; Ogletree, D.F.; Botkin, D.

    1995-05-16

    An ultrafast scanning probe microscopy method is described for achieving subpicosecond-temporal resolution and submicron-spatial resolution of an observation sample. In one embodiment of the present claimed invention, a single short optical pulse is generated and is split into first and second pulses. One of the pulses is delayed using variable time delay means. The first pulse is then directed at an observation sample located proximate to the probe of a scanning probe microscope. The scanning probe microscope produces probe-sample signals indicative of the response of the probe to characteristics of the sample. The second pulse is used to modulate the probe of the scanning probe microscope. The time delay between the first and second pulses is then varied. The probe-sample response signal is recorded at each of the various time delays created between the first and second pulses. The probe-sample response signal is then plotted as a function of time delay to produce a cross-correlation of the probe sample response. In so doing, the present invention provides simultaneous subpicosecond-temporal resolution and submicron-spatial resolution of the sample. 6 Figs.

  17. Environmental Scanning Report, 1992.

    ERIC Educational Resources Information Center

    Yao, Min

    In response to the change in the provincial economy from natural-resource-based industries to service-oriented industries, Vancouver Community College (VCC) in British Columbia (BC) conducted an environmental scan of the social and economic trends in the college's service region that will most likely affect prospective students' educational and…

  18. THE 2016 ENVIRONMENTAL SCAN.

    PubMed

    O'Dell, Gene

    2015-09-01

    Every year, the American Hospital Association compiles the Environmental Scan to provide hospital leaders with insight and information about market forces that are likely to affect the health care field. One common theme this year is the pace of change. PMID:26495611

  19. Teaching the SCANS Competencies.

    ERIC Educational Resources Information Center

    Department of Labor, Washington, DC. Secretary's Commission on Achieving Necessary Skills.

    SCANS (the Secretary's Commission on Achieving Necessary Skills) provides definitions of the knowledge students and workers need for workplace success and methods for applying these principles in communities throughout the United States. This document contains six articles that give education and training practitioners practical suggestions for…

  20. Heel Ultrasound Scan in Detecting Osteoporosis in Low Trauma Fracture Patients.

    PubMed

    Hashmi, Faiz R; Elfandi, Khaled O

    2016-06-27

    Osteoporosis is the most common metabolic disease with significant impact on the morbidity and mortality of affected patients. Osteoporosis has a significant impact on the economy worldwide. The aim of this study was to find out whether heel ultrasound is as good as central bone densitometry scanning in diagnosing osteoporosis in patients who are at high risk of osteoporosis. This was a prospective study of patients comparing heel ultrasound to central bone densitometry scanning (dual X-ray absorptiometry, DEXA) in patients. The recruited patients attended for a DEXA scan of the left hip and lumbar spine. All subjects had an ultrasound of the left heel using the quantitative heel ultrasound machine. The results of DEXA scan were blinded from the results of ultrasound and vice versa. There were 59 patients who took part in the study, 12 men and 47 women. The mean age was 66 years (SD 11.9) and mean weight was 62.5 kg (SD 10.7). The sensitivity and specificity of the ultrasound heel test to predict osteoporosis were 53% (95%CI: 29-77) and 86% (95%CI: 75-96) respectively. Specificity for predicting bone mineral density (BMD)-defined osteoporosis was high (86%), but sensitivity was low (53%). A heel ultrasound result in the osteoporotic range was highly predictive of BMD-defined osteoporosis. A positive ultrasound heel test in high risk patients is more useful in ruling in osteoporosis than a negative test to rule out osteoporosis. PMID:27433300

  1. Heel Ultrasound Scan in Detecting Osteoporosis in Low Trauma Fracture Patients

    PubMed Central

    Hashmi, Faiz R.; Elfandi, Khaled O.

    2016-01-01

    Osteoporosis is the most common metabolic disease with significant impact on the morbidity and mortality of affected patients. Osteoporosis has a significant impact on the economy worldwide. The aim of this study was to find out whether heel ultrasound is as good as central bone densitometry scanning in diagnosing osteoporosis in patients who are at high risk of osteoporosis. This was a prospective study of patients comparing heel ultrasound to central bone densitometry scanning (dual X-ray absorptiometry, DEXA) in patients. The recruited patients attended for a DEXA scan of the left hip and lumbar spine. All subjects had an ultrasound of the left heel using the quantitative heel ultrasound machine. The results of DEXA scan were blinded from the results of ultrasound and vice versa. There were 59 patients who took part in the study, 12 men and 47 women. The mean age was 66 years (SD 11.9) and mean weight was 62.5 kg (SD 10.7). The sensitivity and specificity of the ultrasound heel test to predict osteoporosis were 53% (95%CI: 29-77) and 86% (95%CI: 75-96) respectively. Specificity for predicting bone mineral density (BMD)-defined osteoporosis was high (86%), but sensitivity was low (53%). A heel ultrasound result in the osteoporotic range was highly predictive of BMD-defined osteoporosis. A positive ultrasound heel test in high risk patients is more useful in ruling in osteoporosis than a negative test to rule out osteoporosis. PMID:27433300

  2. Lung Ventilation/Perfusion Scan

    MedlinePlus

    ... from the NHLBI on Twitter. What Is a Lung Ventilation/Perfusion Scan? A lung ventilation/perfusion scan, or VQ scan, is a ... that measures air and blood flow in your lungs. A VQ scan most often is used to ...

  3. Scanning thermal plumes

    NASA Technical Reports Server (NTRS)

    Scarpace, F. L.; Madding, R. P.; Green, T., III

    1975-01-01

    Over a three-year period 800 thermal line scans of power plant plumes were made by an airborne scanner, with ground truth measured concurrently at the plants. Computations using centered finite differences in the thermal scanning imagery show a lower bound in the horizontal temperature gradient in excess of 1.6 C/m. Gradients persist to 3 m below the surface. Vector plots of the velocity of thermal fronts are constructed by tracing the front motion in successive thermal images. A procedure is outlined for the two-point ground calibration of a thermal scanner from an equation describing the scanner signal and the voltage for two known temperatures. The modulation transfer function is then calculated by input of a thermal step function and application of digital time analysis techniques using Fast Fourier Transforms to the voltage output. Field calibration tests are discussed. Data accuracy is limited by the level of ground truth effort chosen.

  4. Fly-scan ptychography

    PubMed Central

    Huang, Xiaojing; Lauer, Kenneth; Clark, Jesse N.; Xu, Weihe; Nazaretski, Evgeny; Harder, Ross; Robinson, Ian K.; Chu, Yong S.

    2015-01-01

    We report an experimental ptychography measurement performed in fly-scan mode. With a visible-light laser source, we demonstrate a 5-fold reduction of data acquisition time. By including multiple mutually incoherent modes into the incident illumination, high quality images were successfully reconstructed from blurry diffraction patterns. This approach significantly increases the throughput of ptychography, especially for three-dimensional applications and the visualization of dynamic systems. PMID:25766519

  5. Scanning micro-sclerometer

    DOEpatents

    Oliver, Warren C.; Blau, Peter J.

    1994-01-01

    A scanning micro-sclerometer measures changes in contact stiffness and correlates these changes to characteristics of a scratch. A known force is applied to a contact junction between two bodies and a technique employing an oscillating force is used to generate the contact stiffness between the two bodies. As the two bodies slide relative to each other, the contact stiffness changes. The change is measured to characterize the scratch.

  6. Fly-scan ptychography

    DOE PAGES

    Huang, Xiaojing; Lauer, Kenneth; Clark, Jesse N.; Xu, Weihe; Nazaretski, Evgeny; Harder, Ross; Robinson, Ian K.; Chu, Yong S.

    2015-03-13

    We report an experimental ptychography measurement performed in fly-scan mode. With a visible-light laser source, we demonstrate a 5-fold reduction of data acquisition time. By including multiple mutually incoherent modes into the incident illumination, high quality images were successfully reconstructed from blurry diffraction patterns. This approach significantly increases the throughput of ptychography, especially for three-dimensional applications and the visualization of dynamic systems.

  7. Scanning micro-sclerometer

    DOEpatents

    Oliver, W.C.; Blau, P.J.

    1994-11-01

    A scanning micro-sclerometer measures changes in contact stiffness and correlates these changes to characteristics of a scratch. A known force is applied to a contact junction between two bodies and a technique employing an oscillating force is used to generate the contact stiffness between the two bodies. As the two bodies slide relative to each other, the contact stiffness changes. The change is measured to characterize the scratch. 2 figs.

  8. Scanning ultrafast electron microscopy

    PubMed Central

    Yang, Ding-Shyue; Mohammed, Omar F.; Zewail, Ahmed H.

    2010-01-01

    Progress has been made in the development of four-dimensional ultrafast electron microscopy, which enables space-time imaging of structural dynamics in the condensed phase. In ultrafast electron microscopy, the electrons are accelerated, typically to 200 keV, and the microscope operates in the transmission mode. Here, we report the development of scanning ultrafast electron microscopy using a field-emission-source configuration. Scanning of pulses is made in the single-electron mode, for which the pulse contains at most one or a few electrons, thus achieving imaging without the space-charge effect between electrons, and still in ten(s) of seconds. For imaging, the secondary electrons from surface structures are detected, as demonstrated here for material surfaces and biological specimens. By recording backscattered electrons, diffraction patterns from single crystals were also obtained. Scanning pulsed-electron microscopy with the acquired spatiotemporal resolutions, and its efficient heat-dissipation feature, is now poised to provide in situ 4D imaging and with environmental capability. PMID:20696933

  9. Scanning holographic lidar telescope

    NASA Technical Reports Server (NTRS)

    Schwemmer, Geary K.; Wilkerson, Thomas D.

    1993-01-01

    We have developed a unique telescope for lidar using a holographic optical element (HOE) as the primary optic. The HOE diffracts 532 nm laser backscatter making a 43 deg angle with a normal to its surface to a focus located 130 cm along the normal. The field of view scans a circle as the HOE rotates about the normal. The detector assembly and baffling remain stationary, compared to conventional scanning lidars in which the entire telescope and detector assembly require steering, or which use a large flat steerable mirror in front of the telescope to do the pointing. The spectral bandpass of our HOE is 50 nm (FWHM). Light within that bandpass is spectrally dispersed at 0.6 nm/mm in the focal plane. An aperture stop reduces the bandpass of light reaching the detector from one direction to 1 nm while simultaneously reducing the field of view to 1 mrad. Wavelengths outside the 50 nm spectral bandpass pass undiffracted through HOE to be absorbed by a black backing. Thus, the HOE combines three functions into one optic: the scanning mirror, the focusing mirror, and a narrowband filter.

  10. Forensic Scanning Electron Microscope

    NASA Astrophysics Data System (ADS)

    Keeley, R. H.

    1983-03-01

    The scanning electron microscope equipped with an x-ray spectrometer is a versatile instrument which has many uses in the investigation of crime and preparation of scientific evidence for the courts. Major applications include microscopy and analysis of very small fragments of paint, glass and other materials which may link an individual with a scene of crime, identification of firearms residues and examination of questioned documents. Although simultaneous observation and chemical analysis of the sample is the most important feature of the instrument, other modes of operation such as cathodoluminescence spectrometry, backscattered electron imaging and direct x-ray excitation are also exploited. Marks on two bullets or cartridge cases can be compared directly by sequential scanning with a single beam or electronic linkage of two instruments. Particles of primer residue deposited on the skin and clothing when a gun is fired can be collected on adhesive tape and identified by their morphology and elemental composition. It is also possible to differentiate between the primer residues of different types of ammunition. Bullets may be identified from the small fragments left behind as they pass through the body tissues. In the examination of questioned documents the scanning electron microscope is used to establish the order in which two intersecting ink lines were written and to detect traces of chemical markers added to the security inks on official documents.

  11. Descreening of scanned images

    NASA Astrophysics Data System (ADS)

    Kurilin, Ilya V.; Safonov, Ilia V.; Lee, HoKeun; Kim, Sang Ho

    2010-01-01

    Screen or halftone pattern appears on the majority of images printed on electrophotographic and ink-jet printers as well as offset machines. When such halftoned image is scanned, a noisy effect called a Moiré pattern often appears on the image. There are plenty of methods proposed for descreening of images. Common way is adaptive smoothing of scanned images. However the descreening techniques face the following dilemma: deep screen reduction and restoration of contone images leads to blurring of sharp edges of text and other graphics primitives, on the other hand insufficient smoothing keeps screen in halftoned areas. We propose novel descreening algorithm that is primarily intended for preservation of sharpness and contrast of text edges and for restoration contone images from halftone ones accurately. Proposed technique for descreening of scanned images comprises five steps. The first step is decrease of edge transition slope length via local tone mapping with ordering; it is carried out before adaptive smoothing, and it allows better preservation of edges. Adaptive low-pass filter applies simplified idea of Non-Local Means filter for area classification; similarity is calculated between central block of window and different adjacent block that is selected randomly. If similarity is high then current pixel relates to flat region, otherwise pixel relates to edge region. For prevention of edges blurring, flat regions are smoothed stronger than edge regions. By random selection of blocks we avoid the computational overhead related to excessive directional edge detection. Final three stages include additional decrease of edge transition slope length using local tone mapping, increase of local contrast via modified unsharp mask filter, that uses bilateral filter with special edge-stop function for modest smoothing of edges, and global contrast stretching. These stages are intended to compensate decreasing of sharpness and contrast due to low-pass filtering, it allows

  12. Novel single x-ray absorptiometry method to solve for volumetric breast density in mammograms with paddle tilt

    NASA Astrophysics Data System (ADS)

    Malkov, Serghei; Wang, Jeff; Shepherd, John

    2007-03-01

    We report on the design and validation of a breast tissue equivalent phantom for automated measurement of breast composition in film/screen and digital mammography systems. This phantom is a multi-step phantom made of a single material and containing nine lead positioning markers around its periphery. The markers allow for the phantom position to be solved relative to the x-ray gantry. The phantom was adhered to the top of the mammographic compression paddle such that it projected an attenuation image onto the unused corner of the image without overlapping with CC- nor MLO-view breast edges. The markers and their centroids were identified using automatic morphological image processing operations. The phantom, and thus the paddle, orientation is then obtained by minimizing a simple least-square error function of the difference between a pseudo projection image of the phantom markers at known coordinates and the actual marker image. Fibroglandular-equivalent breast attenuation values were found directly from step phantom projections. Fat attenuation values were derived from the attenuation coefficient ratios of fat to fibroglandular tissue. Finally, breast density was calculated by comparing image pixel values to the fat/fibroglandular references at the same thickness. Multiple scans of a test object (a density step phantom with 7 densities) at nine different compression thicknesses and six paddle-tilt angles were acquired. We found the precision for determining the breast thickness to be 0.015 cm (standard deviation) and for determining individual paddle angles to be 0.05 degrees. Multiple clinical studies using the technique on film/screen and digital mammography machines are also currently under way.

  13. Marked disparity between trabecular and cortical bone loss with age in healthy men. Measurement by vertebral computed tomography and radial photon absorptiometry

    SciTech Connect

    Meier, D.E.; Orwoll, E.S.; Jones, J.M.

    1984-11-01

    To define age-related changes in bone mineral content in normal men, we measured radial (proximal and distal) and vertebral bone mineral content in 62 men aged 30 to 92 years. Radial bone mineral content (largely cortical bone) was measured by single photon absorptiometry, and trabecular vertebral content (T12, L1 to L3) by computed tomography. Radial bone mineral content fell gradually (2% to 3.4% per decade) with age, but vertebral trabecular content fell more rapidly (12% per decade). Body size was not associated with the rate of bone loss from the distal radial and vertebral sites, but men with lower surface areas lost bone more rapidly at the predominantly cortical proximal radial site. The fact that radial cortical bone mineral content falls much less rapidly than vertebral trabecular content with age and is also associated with surface area indicates that trabecular and cortical bone compartments may be independently modulated. Age-related bone loss should not be considered a homogeneous process.

  14. Comparison of Body Composition Assessed by Dual-Energy X-Ray Absorptiometry and BMI in Current and Former U.S. Navy Service Members

    PubMed Central

    Gasier, Heath G.; Hughes, Linda M.; Young, Colin R.; Richardson, Annely M.

    2015-01-01

    Background Little is known of the diagnostic accuracy of BMI in classifying obesity in active duty military personnel and those that previously served. Thus, the primary objectives were to determine the relationship between lean and fat mass, and body fat percentage (BF%) with BMI, and assess the agreement between BMI and BF% in defining obesity. Methods Body composition was measured by dual-energy X-ray absorptiometry in 462 males (20–91 years old) who currently or previously served in the U.S. Navy. A BMI of ≥ 30 kg/m2 and a BF% ≥ 25% were used for obesity classification. Results The mean BMI (± SD) and BF% were 28.8 ± 4.1 and 28.9 ± 6.6%, respectively, with BF% increasing with age. Lean mass, fat mass, and BF% were significantly correlated with BMI for all age groups. The exact agreement of obesity defined by BMI and BF% was fair (61%), however, 38% were misclassified by a BMI cut-off of 30 when obesity was defined by BF%. Conclusions From this data we determined that there is a good correlation between body composition and BMI, and fair agreement between BMI and BF% in classifying obesity in a group of current and former U.S. Navy service members. However, as observed in the general population, a significant proportion of individuals with excess fat are misclassified by BMI cutoffs. PMID:26197480

  15. A phantom based study on the effect of subject positioning on morphometric X-ray absorptiometry using the Lunar Expert-XL.

    PubMed

    Thorpe, J A; Steel, S A; Langton, C M

    1998-11-01

    Morphometric X-ray absorptiometry (MXA) relies on accurate measurement of vertical dimensions of vertebrae from a lateral perspective. Deviations resulting from scoliotic curvature or poor patient positioning produce distortions of visible vertebral dimensions and may lead to analysis error. This study utilized a phantom developed at this centre to assess the effect of vertebral malalignment on the accuracy of the MXA technique on the Lunar Expert-XL. Measured vertebral heights were found to be consistently underestimated by an average of 3.7%. Precision ranged from 0.79% for anterior height measurement to 1.03% for middle height measurement. Vertebral malalignment was investigated as the effect of rotation around the anteroposterior, lateral and superoinferior axes. Rotation around the lateral axis produced little discernible effect. However, superoinferior axial rotation showed a change of more than two standard deviations in the mid/posterior ratios of biconcave vertebrae at comparatively small angles of rotation. Anteroposterior axial rotation produced an increase in observed height at small angles of rotation, and a rapid decrease in vertebral height as rotation increased. The results suggest that whilst kyphosis or lordosis of up to at least 5.8 degrees has a minimal effect on MXA, scoliosis of 4.6 degrees or above produces a distinctive effect on the defining crush height ratios.

  16. Evaluation of the effects of hypergravity exposure and caging restraint on bone mineralization in the Beagle by in vivo photon absorptiometry

    NASA Technical Reports Server (NTRS)

    Fisher, G. L.; Berding, K. L.; Goldman, M.

    1975-01-01

    Photon absorptiometry was used to evaluate bone mineral kinetics associated with normal development and the possible perturbations to bone development resulting from hypergravity exposure over a period of six months in developing Beagles. A series of seven measurements were performed at specific times with the first measurement prior to treatment and subsequent measurements at 2, 5, 9, 14, 20 and 26 weeks from the onset of the experiment. Four groups of six male Beagle pups, ranging in age from 85 to 92 days were studied. Two groups were chronically exposed to hypergravity treatments by centrifugation of 2.0 G (18.0 RPM, 11.7 ft radius) and 2.6 G (18.0 RPM, 19.8 ft radius) for the 26 week period. A third group of six dogs served as a caged control to evaluate possible changes due to confinement in small plexiglass cages similar to those of the centrifuge. Thus this control group was subjected to limited exercise due to caging restraint. The fourth group of animals was housed in open runs to allow exercise without the spatial confinement of the smaller plexiglass cages. Results show highly significant differences in body weight, bone length, increase in bone density of control group relative to other groups, and a decrease in bone mineral content in the two gravity treated groups.

  17. Free motion scanning system

    DOEpatents

    Sword, Charles K.

    2000-01-01

    The present invention relates to an ultrasonic scanner system and method for the imaging of a part system, the scanner comprising: a probe assembly spaced apart from the surface of the part including at least two tracking signals for emitting radiation and a transmitter for emitting ultrasonic waves onto a surface in order to induce at least a portion of the waves to be reflected from the part, at least one detector for receiving the radiation wherein the detector is positioned to receive the radiation from the tracking signals, an analyzer for recognizing a three-dimensional location of the tracking signals based on the emitted radiation, a differential converter for generating an output signal representative of the waveform of the reflected waves, and a device such as a computer for relating said tracking signal location with the output signal and projecting an image of the resulting data. The scanner and method are particularly useful to acquire ultrasonic inspection data by scanning the probe over a complex part surface in an arbitrary scanning pattern.

  18. Ultrafast scanning tunneling microscopy

    SciTech Connect

    Botkin, D.A. |

    1995-09-01

    I have developed an ultrafast scanning tunneling microscope (USTM) based on uniting stroboscopic methods of ultrafast optics and scanned probe microscopy to obtain nanometer spatial resolution and sub-picosecond temporal resolution. USTM increases the achievable time resolution of a STM by more than 6 orders of magnitude; this should enable exploration of mesoscopic and nanometer size systems on time scales corresponding to the period or decay of fundamental excitations. USTM consists of a photoconductive switch with subpicosecond response time in series with the tip of a STM. An optical pulse from a modelocked laser activates the switch to create a gate for the tunneling current, while a second laser pulse on the sample initiates a dynamic process which affects the tunneling current. By sending a large sequence of identical pulse pairs and measuring the average tunnel current as a function of the relative time delay between the pulses in each pair, one can map the time evolution of the surface process. USTM was used to measure the broadband response of the STM`s atomic size tunnel barrier in frequencies from tens to hundreds of GHz. The USTM signal amplitude decays linearly with the tunnel junction conductance, so the spatial resolution of the time-resolved signal is comparable to that of a conventional STM. Geometrical capacitance of the junction does not appear to play an important role in the measurement, but a capacitive effect intimately related to tunneling contributes to the measured signals and may limit the ultimate resolution of the USTM.

  19. A-Scan Echoencephalography

    PubMed Central

    White, D. Naldrett

    1966-01-01

    The technique of A-scan echoencephalography is criticized in so far as it lacks objectivity and reproducibility. In the author's laboratory, the M-echo, being of higher amplitude than other intracranial echoes, is distinguished from other echoes by an averaging technique—a time exposure. Double transmission pulses indicate the theoretical position of echoes from the true mid-line and superimposition of far-side echoes ensures that the transducers are correctly aligned. The very considerable difficulties in identifying the anatomical structures giving rise to other echoes seen within the skull are outlined. They are largely due to variations in the reflected energy, depending upon the shape and orientation and position of the various interfaces with respect to the ultrasonic beam. Despite these difficulties and limitations, A-scan echoencephalography appears to have an important part to play as a simple, safe and quick form of neurological examination, if the technique can be made truly objective. ImagesFig. 1Fig. 9Fig. 10 PMID:5901162

  20. Quadrature wavelength scanning interferometry.

    PubMed

    Moschetti, Giuseppe; Forbes, Alistair; Leach, Richard K; Jiang, Xiang; O'Connor, Daniel

    2016-07-10

    A novel method to double the measurement range of wavelength scanning interferometery (WSI) is described. In WSI the measured optical path difference (OPD) is affected by a sign ambiguity, that is, from an interference signal it is not possible to distinguish whether the OPD is positive or negative. The sign ambiguity can be resolved by measuring an interference signal in quadrature. A method to obtain a quadrature interference signal for WSI is described, and a theoretical analysis of the advantages is reported. Simulations of the advantages of the technique and of signal errors due to nonideal quadrature are discussed. The analysis and simulation are supported by experimental measurements to show the improved performances. PMID:27409307

  1. Scanning electrochemical microscopy.

    PubMed

    Amemiya, Shigeru; Bard, Allen J; Fan, Fu-Ren F; Mirkin, Michael V; Unwin, Patrick R

    2008-01-01

    This review describes work done in scanning electrochemical microscopy (SECM) since 2000 with an emphasis on new applications and important trends, such as nanometer-sized tips. SECM has been adapted to investigate charge transport across liquid/liquid interfaces and to probe charge transport in thin films and membranes. It has been used in biological systems like single cells to study ion transport in channels, as well as cellular and enzyme activity. It is also a powerful and useful tool for the evaluation of the electrocatalytic activities of different materials for useful reactions, such as oxygen reduction and hydrogen oxidation. SECM has also been used as an electrochemical tool for studies of the local properties and reactivity of a wide variety of materials, including metals, insulators, and semiconductors. Finally, SECM has been combined with several other nonelectrochemical techniques, such as atomic force microscopy, to enhance and complement the information available from SECM alone.

  2. Scanning quantum decoherence microscopy

    NASA Astrophysics Data System (ADS)

    Cole, Jared H.; Hollenberg, Lloyd C. L.

    2009-12-01

    The use of qubits as sensitive nanoscale magnetometers has been studied theoretically and recently demonstrated experimentally. In this paper we propose a new concept, in which a scanning two-state quantum system is used to probe a sample through the subtle effects of decoherence. Mapping both the Hamiltonian and decoherence properties of a qubit simultaneously provides a unique image of the magnetic (or electric) field properties at the nanoscale. The resulting images are sensitive to the temporal as well as spatial variation in the fields created by the sample. As examples we theoretically study two applications; one from condensed matter physics, the other biophysics. The individual components required to realize the simplest version of this device (characterization and measurement of qubits, nanoscale positioning) have already been demonstrated experimentally.

  3. A scanning cavity microscope.

    PubMed

    Mader, Matthias; Reichel, Jakob; Hänsch, Theodor W; Hunger, David

    2015-01-01

    Imaging the optical properties of individual nanosystems beyond fluorescence can provide a wealth of information. However, the minute signals for absorption and dispersion are challenging to observe, and only specialized techniques requiring sophisticated noise rejection are available. Here we use signal enhancement in a high-finesse scanning optical microcavity to demonstrate ultra-sensitive imaging. Harnessing multiple interactions of probe light with a sample within an optical resonator, we achieve a 1,700-fold signal enhancement compared with diffraction-limited microscopy. We demonstrate quantitative imaging of the extinction cross-section of gold nanoparticles with a sensitivity less than 1 nm(2); we show a method to improve the spatial resolution potentially below the diffraction limit by using higher order cavity modes, and we present measurements of the birefringence and extinction contrast of gold nanorods. The demonstrated simultaneous enhancement of absorptive and dispersive signals promises intriguing potential for optical studies of nanomaterials, molecules and biological nanosystems. PMID:26105690

  4. Metrological scanning probe microscope

    NASA Astrophysics Data System (ADS)

    Dorozhovets, N.; Hausotte, T.; Manske, E.; Jäger, G.; Hofmann, N.

    2006-04-01

    Today's technological progress calls for metrologically accurate object measurement, positioning and scanning with nanometre precision and over large measuring ranges. In order to meet that requirement a nanopositioning and nanomeasuring machine (NPM machine) was developed at the Institute of Process Measurement and Sensor Technology of the Technische Universitaet Ilmenau. This device is capable of highly exact long-range positioning and measurement of objects with a resolution of less than 0.1 nm. Due to the structure of the machine many different probe systems can be installed, including scanning probe microscopes (SPMs). A few SPMs have outstanding metrological characteristics and many commercial microscopes only perform as image acquisition tools. Commercial SPMs use piezoelectric actuators in order to move either the sample or the probe. The position measurement sometimes results from the applied voltage to the piezoelectric actuators or from the strain gauge or capacitive displacement sensor data. This means that they suffer from hysteresis, creep, nonlinear characteristics and Abbe offsets. For an accurate measurement the position of the cantilever must be measured in addition to the torsion and bending. The best solution is a combined detection system with a single laser beam. This system has been realized with a special interferometer system, in which the measuring beam is focused on the cantilever backside using a lens. The reflected beam is split with a part being detected by a quadrant photo-diode and the other part being fed back into the interferometer for position measurement. The quadrant photo-diode is used to detect the cantilever torsion and bending.

  5. Rapid scanning mass spectrometer

    SciTech Connect

    Leckey, J.H.; Boeckmann, M.D.

    1996-11-25

    Mass spectrometers and residual gas analyzers (RGA) are used in a variety of applications for analysis of volatile and semi-volatile materials. Analysis is performed by detecting fragments of gas molecules, based on their mass to charge ratio, which are generated in the mass spectrometer. When used as a detector for a gas chromatograph, they function as a means to quantitatively identify isolated volatile species which have been separated from other species via the gas chromatograph. Vacuum Technology, Inc., (VTI) produces a magnetic sector mass spectrometer/RGA which is used in many industrial and laboratory environments. In order to increase the utility of this instrument, it is desirable to increase the mass scanning speed, thereby increasing the number of applications for which it is suited. This project performed the following three upgrades on the computer interface. (1) A new electrometer was designed and built to process the signal from the detector. This new electrometer is more sensitive, over 10 times faster, and over 100 times more stable than the electrometer it will replace. (2) The controller EPROM was reprogrammed with new firmware. This firmware acts as an operating system for the interface and is used to shuttle communications between the PC and the AEROVAC mass spectrometer. (3) The voltage regulator which causes the ion selector voltage to ramp to allow ions of selected mass to be sequentially detected was redesigned and prototyped. The redesigned voltage regulator can be ramped up or down more than 100 times faster than the existing regulator. These changes were incorporated into a prototype unit and preliminary performance testing conducted. Results indicated that scanning speed was significantly increased over the unmodified version.

  6. Scan mirrors relay for high resolution laser scanning systems

    NASA Astrophysics Data System (ADS)

    Kessler, David

    2014-09-01

    Two dimensional beam deflection is often required in medical laser scanning systems such as OCT or confocal microscopy. Commonly two linear galvo mirrors are used for performance in terms of their large apertures and scan angles. The galvo mirrors are placed at the vicinity of entrance pupil of the scan lens with a "displacement distance" separating them. This distance limits the scan fields and/or reduces the effective aperture of the scan lens. Another option is to use a beam or pupil relay, and image one galvo mirror onto the other. However, beam (or pupil) relays are notoriously complicated, expensive and can add significant aberrations. This paper discusses a simple, all reflective, diffraction limited, color corrected, beam relay, capable of large scan angles and large deflecting mirrors. The design is based on a unique combination of an Offner configuration with a Schmidt aspheric corrector. The design is highly corrected up to large scan mirrors and large scan angles down to milliwaves of aberrations. It allows significantly larger scan field and or scan lenses with higher numerical aperture as compared with scanners using galvos separated by the displacement distance. While this relay is of exceptionally high performance, it has one element located where the beam is focused which may present a problem for high power lasers. Thus modifications of the above design are introduced where the beam is focused in mid air thus making it usable for high power systems such including laser marking and fabrication systems.

  7. Earth observing scanning polarimeter

    NASA Technical Reports Server (NTRS)

    Travis, Larry

    1993-01-01

    Climate forcing by tropospheric aerosols is receiving increased attention because of the realization that the climate effects may be large, while our knowledge of global aerosol characteristics and temporal changes is very poor. Tropospheric aerosols cause a direct radiative forcing due simply to their scattering and absorption of solar radiation, as well as an indirect effect as cloud condensation nuclei which can modify the shortwave reflectivity of clouds. Sulfate aerosols tend to increase planetary albedo through both the direct and indirect effects; a cooling due to anthropogenic sulfate aerosols has been estimated of order 1 W/sq m, noting that this is similar in magnitude to the present anthropogenic greenhouse gas warming. Other aerosols, including those from biomass burning and wind-blown desert dust are also of potential climatic importance. At present, the only global monitoring of tropospheric aerosols is a NOAA operational product, aerosol optical thickness, obtained using channel-1 (0.58-0.68 mu m) radiances from the AVHRR. With this single channel radiance data, one must use an approach which is based on the inferred excess of reflected radiance owing to scattering by the aerosols over that expected from theoretical calculations. This approach is suited only for situations where the surface has a low albedo that is well known a priori. Thus, the NOAA operational product is restricted to coverage over the ocean at AVHRR scan angles well away from sun glint, and aerosol changes are subject to confusion with changes caused by either optically thin or subpixel clouds. Because optically thin aerosols have only a small effect on the radiance, accurate measurements for optical thickness less than 0.1 (which is a typical background level) are precluded. Moreover, some of the largest and most important aerosol changes are expected over land. The Earth Observing Scanning Polarimeter (EOSP) instrument, based upon design heritage and analysis techniques

  8. Measurement of bone mineral density by dual-energy x-ray absorptiometry in patients with the Wisconsin hip, an uncemented femoral stem.

    PubMed

    Kiratli, B J; Checovich, M M; McBeath, A A; Wilson, M A; Heiner, J P

    1996-02-01

    Although qualitative evidence of femoral bone remodeling, secondary to total hip arthroplasty (THA), is apparent on radiographs, quantification of change in bone mass from radiographs is limited. Dual-energy x-ray absorptiometry overcomes many of the limitations and yields accurate and precise bone mineral density (BMD) data. In this study, regional changes in femoral BMD were examined in 89 THA patients with a 2-year follow-up period. Thirty-two patients were evaluated initially before surgery and followed through the first 2 postoperative years. A second group was comprised of 57 patients whose surgery had been performed 1 to 6 years prior to entry into the study; they were also followed for 2 years hence. Thus, both immediate and later bone responses were evaluated prospectively. Maximal bone remodeling was seen in the first 6 months after THA and with a near plateau by the end of the first year. A slow yearly decline in BMD appeared to occur as long as 8 years after THA, thus demonstrating the long-term effects of the introduction of a femoral stem. Variance in preoperative BMD was explained by disease only; no other factors (age, weight, sex) showed significant associations, and body weight was the only variable that affected rate of remodeling after THA (not age, weight, sex, prosthesis size, nor disease). All patients were healthy, relatively young individuals who were good candidates for uncemented implantation, and none showed evidence of clinical complications or surgical failure. It is therefore suggested that the patterns and results reported here be viewed as normative data, that is, the typical skeletal adaptation to THA. In future application, observation of disparate BMD results as compared with these "normal" data may be predictive of abnormal response to surgery and potential for later problems.

  9. LANL Robotic Vessel Scanning

    SciTech Connect

    Webber, Nels W.

    2015-11-25

    Los Alamos National Laboratory in J-1 DARHT Operations Group uses 6ft spherical vessels to contain hazardous materials produced in a hydrodynamic experiment. These contaminated vessels must be analyzed by means of a worker entering the vessel to locate, measure, and document every penetration mark on the vessel. If the worker can be replaced by a highly automated robotic system with a high precision scanner, it will eliminate the risks to the worker and provide management with an accurate 3D model of the vessel presenting the existing damage with the flexibility to manipulate the model for better and more in-depth assessment.The project was successful in meeting the primary goal of installing an automated system which scanned a 6ft vessel with an elapsed time of 45 minutes. This robotic system reduces the total time for the original scope of work by 75 minutes and results in excellent data accumulation and transmission to the 3D model imaging program.

  10. GPR scan assessment

    NASA Astrophysics Data System (ADS)

    Abbas, Abbas M.; Salah, Hany; Massoud, Usama; Fouad, Mona; Abdel-Hafez, Mahmoud

    2015-06-01

    Mekaad Radwan monument is situated in the neighborhood of Bab Zuweila in the historical Cairo, Egypt. It was constructed at the middle XVII century (1635 AD). The building has a rectangle shape plan (13 × 6 m) with the longitudinal sides approximately WNW-ESE. It comprises three storages namely; the ground floor; the opened floor (RADWAN Bench) and the living floor with a total elevation of 15 m above the street level. The building suffers from severe deterioration phenomena with patterns of damage which have occurred over time. These deterioration and damages could be attributed to foundation problems, subsoil water and also to the earthquake that affected the entire Greater Cairo area in October 1992. Ground Penetrating Radar (GPR) scan was accomplished against the walls of the opened floor (RADWAN Bench) to evaluate the hazard impact on the walls textures and integrity. The results showed an anomalous feature through the southern wall of RADWAN Bench. A mathematical model has been simulated to confirm the obtained anomaly and the model response exhibited a good matching with the outlined anomaly.

  11. Laser Scanning Cytometry

    PubMed Central

    Pozarowski, Piotr; Holden, Elena; Darzynkiewicz, Zbigniew

    2013-01-01

    Summary The laser scanning cytometer (LSC) is the microscope-based cytofluorometer that offers a plethora of analytical capabilities. Multilaser-excited fluorescence emitted from individual cells is measured at several wavelength ranges, rapidly (up to 5000 cells/min), with high sensitivity and accuracy. The following applications of LSC are reviewed: (1) identification of cells that differ in degree of chromatin condensation (e.g., mitotic or apoptotic cells or lymphocytes vs granulocytes vs monocytes); (2) detection of translocation between cytoplasm vs nucleus or nucleoplasm vs nucleolus of regulatory molecules such as NF- κB, p53, or Bax; (3) semiautomatic scoring of micronuclei in mutagenicity assays; (4) analysis of fluorescence in situ hybridization; (5) enumeration and morphometry of nucleoli; (6) analysis of phenotype of progeny of individual cells in clonogenicity assay; (7) cell immunophenotyping; (8) visual examination, imaging, or sequential analysis of the cells measured earlier upon their relocation, using different probes; (9) in situ enzyme kinetics and other time-resolved processes; (10) analysis of tissue section architecture; (11) application for hypocellular samples (needle aspirate, spinal fluid, etc.); (12) other clinical applications. Advantages and limitations of LSC are discussed and compared with flow cytometry. PMID:16719355

  12. Use of prediction equations to determine the accuracy of whole-body fat and fat-free mass and appendicular skeletal muscle mass measurements from a single abdominal image using computed tomography in advanced cancer patients.

    PubMed

    Kilgour, Robert D; Cardiff, Katrina; Rosenthall, Leonard; Lucar, Enriqueta; Trutschnigg, Barbara; Vigano, Antonio

    2016-01-01

    Measurements of body composition using dual-energy X-ray absorptiometry (DXA) and single abdominal images from computed tomography (CT) in advanced cancer patients (ACP) have important diagnostic and prognostic value. The question arises as to whether CT scans can serve as surrogates for DXA in terms of whole-body fat-free mass (FFM), whole-body fat mass (FM), and appendicular skeletal muscle (ASM) mass. Predictive equations to estimate body composition for ACP from CT images have been proposed (Mourtzakis et al. 2008; Appl. Physiol. Nutr. Metabol. 33(5): 997-1006); however, these equations have yet to be validated in an independent cohort of ACP. Thus, this study evaluated the accuracy of these equations in estimating FFM, FM, and ASM mass using CT images at the level of the third lumbar vertebrae and compared these values with DXA measurements. FFM, FM, and ASM mass were estimated from the prediction equations proposed by Mourtzakis and colleagues (2008) using single abdominal CT images from 43 ACP and were compared with whole-body DXA scans using Spearman correlations and Bland-Altman analyses. Despite a moderate to high correlation between the actual (DXA) and predicted (CT) values for FM (rho = 0.93; p ≤ 0.001), FFM (rho = 0.78; p ≤ 0.001), and ASM mass (rho = 0.70; p ≤ 0.001), Bland-Altman analyses revealed large range-of-agreement differences between the 2 methods (29.39 kg for FFM, 15.47 kg for FM, and 3.99 kg for ASM mass). Based on the magnitude of these differences, we concluded that prediction equations using single abdominal CT images have poor accuracy, cannot be considered as surrogates for DXA, and may have limited clinical utility. PMID:26695688

  13. Radioisotope scanning in osseous sarcoidosis

    SciTech Connect

    Rohatgi, P.K.

    1980-01-01

    Technetium-99m (/sup 99m/Tc)-labeled pyrophosphate or diphosphonate compounds and gallium-67 citrate (/sup 67/Ga) are two radionuclide scanning agents that are in widespread use in clinical practice. Technetium-99m pyrophosphate is used extensively for bone scanning to detect metastatic bone disease, benign bone tumors, osteomyelitis, benign hypertrophic osteoarthropathy, and Paget's disease. Only two reports describe abnormal /sup 99m/Tc/ pyrophosphate bone scans in four patients with osseous sarcoidosis. Gallium-67 scans are used primarily to localize neoplastic or inflammatory lesions anywhere in the body. In recent years /sup 67/Ga scans have also been used to detect the presence of both pulmonary and extrapulmonary sarcoidosis, but there are no reports describing abnormal uptake of gallium in patients with osseous sarcoidosis. This report describes experience with radioisotope scanning in two patients with osseous sarcoidosis.

  14. Stochastic scanning multiphoton multifocal microscopy.

    PubMed

    Jureller, Justin E; Kim, Hee Y; Scherer, Norbert F

    2006-04-17

    Multiparticle tracking with scanning confocal and multiphoton fluorescence imaging is increasingly important for elucidating biological function, as in the transport of intracellular cargo-carrying vesicles. We demonstrate a simple rapid-sampling stochastic scanning multifocal multiphoton microscopy (SS-MMM) fluorescence imaging technique that enables multiparticle tracking without specialized hardware at rates 1,000 times greater than conventional single point raster scanning. Stochastic scanning of a diffractive optic generated 10x10 hexagonal array of foci with a white noise driven galvanometer yields a scan pattern that is random yet space-filling. SS-MMM creates a more uniformly sampled image with fewer spatio-temporal artifacts than obtained by conventional or multibeam raster scanning. SS-MMM is verified by simulation and experimentally demonstrated by tracking microsphere diffusion in solution. PMID:19516485

  15. The bone scan.

    PubMed

    Brenner, Arnold I; Koshy, June; Morey, Jose; Lin, Cheryl; DiPoce, Jason

    2012-01-01

    Bone imaging continues to be the second greatest-volume nuclear imaging procedure, offering the advantage of total body examination, low cost, and high sensitivity. Its power rests in the physiological uptake and pathophysiologic behavior of 99m technetium (99m-Tc) diphosphonates. The diagnostic utility, sensitivity, specificity, and predictive value of 99m-Tc bone imaging for benign conditions and tumors was established when only planar imaging was available. Currently, nearly all bone scans are performed as a planar study (whole-body, 3-phase, or regional), with the radiologist often adding single-photon emission computed tomography (SPECT) imaging. Here we review many current indications for planar bone imaging, highlighting indications in which the planar data are often diagnostically sufficient, although diagnosis may be enhanced by SPECT. (18)F sodium fluoride positron emission tomography (PET) is also re-emerging as a bone agent, and had been considered interchangeable with 99m-Tc diphosphonates in the past. In addition to SPECT, new imaging modalities, including (18)F fluorodeoxyglucose, PET/CT, CT, magnetic resonance, and SPECT/CT, have been developed and can aid in evaluating benign and malignant bone disease. Because (18)F fluorodeoxyglucose is taken up by tumor cells and Tc diphosphonates are taken up in osteoblastic activity or osteoblastic healing reaction, both modalities are complementary. CT and magnetic resonance may supplement, but do not replace, bone imaging, which often detects pathology before anatomic changes are appreciated. We also stress the importance of dose reduction by reducing the dose of 99m-Tc diphosphonates and avoiding unnecessary CT acquisitions. In addition, we describe an approach to image interpretation that emphasizes communication with referring colleagues and correlation with appropriate history to significantly improve our impact on patient care.

  16. Nuclear Medicine Scans for Cancer

    MedlinePlus

    ... are the possible complications? For the most part, nuclear scans are safe tests. The doses of radiation are very small, and the radionuclides have a ... else should I know about these tests? The radiation exposure from a nuclear scan comes from the radionuclides used – the scanner ...

  17. An interchangeable scanning Hall probe/scanning SQUID microscope

    SciTech Connect

    Tang, Chiu-Chun; Lin, Hui-Ting; Wu, Sing-Lin; Chen, Tse-Jun; Wang, M. J.; Ling, D. C.; Chi, C. C.; Chen, Jeng-Chung

    2014-08-15

    We have constructed a scanning probe microscope for magnetic imaging, which can function as a scanning Hall probe microscope (SHPM) and as a scanning SQUID microscope (SSM). The scanning scheme, applicable to SHPM and SSM, consists of a mechanical positioning (sub) micron-XY stage and a flexible direct contact to the sample without a feedback control system for the Z-axis. With the interchangeable capability of operating two distinct scanning modes, our microscope can incorporate the advantageous functionalities of the SHPM and SSM with large scan range up to millimeter, high spatial resolution (⩽4 μm), and high field sensitivity in a wide range of temperature (4.2 K-300 K) and magnetic field (10{sup −7} T-1 T). To demonstrate the capabilities of the system, we present magnetic images scanned with SHPM and SSM, including a RbFeB magnet and a nickel grid pattern at room temperature, surface magnetic domain structures of a La{sub 2/3}Ca{sub 1/3}MnO{sub 3} thin film at 77 K, and superconducting vortices in a striped niobium film at 4.2 K.

  18. An interchangeable scanning Hall probe/scanning SQUID microscope.

    PubMed

    Tang, Chiu-Chun; Lin, Hui-Ting; Wu, Sing-Lin; Chen, Tse-Jun; Wang, M J; Ling, D C; Chi, C C; Chen, Jeng-Chung

    2014-08-01

    We have constructed a scanning probe microscope for magnetic imaging, which can function as a scanning Hall probe microscope (SHPM) and as a scanning SQUID microscope (SSM). The scanning scheme, applicable to SHPM and SSM, consists of a mechanical positioning (sub) micron-XY stage and a flexible direct contact to the sample without a feedback control system for the Z-axis. With the interchangeable capability of operating two distinct scanning modes, our microscope can incorporate the advantageous functionalities of the SHPM and SSM with large scan range up to millimeter, high spatial resolution (⩽4 μm), and high field sensitivity in a wide range of temperature (4.2 K-300 K) and magnetic field (10(-7) T-1 T). To demonstrate the capabilities of the system, we present magnetic images scanned with SHPM and SSM, including a RbFeB magnet and a nickel grid pattern at room temperature, surface magnetic domain structures of a La(2/3)Ca(1/3)MnO3 thin film at 77 K, and superconducting vortices in a striped niobium film at 4.2 K. PMID:25173276

  19. An interchangeable scanning Hall probe/scanning SQUID microscope.

    PubMed

    Tang, Chiu-Chun; Lin, Hui-Ting; Wu, Sing-Lin; Chen, Tse-Jun; Wang, M J; Ling, D C; Chi, C C; Chen, Jeng-Chung

    2014-08-01

    We have constructed a scanning probe microscope for magnetic imaging, which can function as a scanning Hall probe microscope (SHPM) and as a scanning SQUID microscope (SSM). The scanning scheme, applicable to SHPM and SSM, consists of a mechanical positioning (sub) micron-XY stage and a flexible direct contact to the sample without a feedback control system for the Z-axis. With the interchangeable capability of operating two distinct scanning modes, our microscope can incorporate the advantageous functionalities of the SHPM and SSM with large scan range up to millimeter, high spatial resolution (⩽4 μm), and high field sensitivity in a wide range of temperature (4.2 K-300 K) and magnetic field (10(-7) T-1 T). To demonstrate the capabilities of the system, we present magnetic images scanned with SHPM and SSM, including a RbFeB magnet and a nickel grid pattern at room temperature, surface magnetic domain structures of a La(2/3)Ca(1/3)MnO3 thin film at 77 K, and superconducting vortices in a striped niobium film at 4.2 K.

  20. Large aperture scanning airborne lidar

    NASA Technical Reports Server (NTRS)

    Smith, J.; Bindschadler, R.; Boers, R.; Bufton, J. L.; Clem, D.; Garvin, J.; Melfi, S. H.

    1988-01-01

    A large aperture scanning airborne lidar facility is being developed to provide important new capabilities for airborne lidar sensor systems. The proposed scanning mechanism allows for a large aperture telescope (25 in. diameter) in front of an elliptical flat (25 x 36 in.) turning mirror positioned at a 45 degree angle with respect to the telescope optical axis. The lidar scanning capability will provide opportunities for acquiring new data sets for atmospheric, earth resources, and oceans communities. This completed facility will also make available the opportunity to acquire simulated EOS lidar data on a near global basis. The design and construction of this unique scanning mechanism presents exciting technological challenges of maintaining the turning mirror optical flatness during scanning while exposed to extreme temperatures, ambient pressures, aircraft vibrations, etc.

  1. Re-scan confocal microscopy: scanning twice for better resolution.

    PubMed

    De Luca, Giulia M R; Breedijk, Ronald M P; Brandt, Rick A J; Zeelenberg, Christiaan H C; de Jong, Babette E; Timmermans, Wendy; Azar, Leila Nahidi; Hoebe, Ron A; Stallinga, Sjoerd; Manders, Erik M M

    2013-01-01

    We present a new super-resolution technique, Re-scan Confocal Microscopy (RCM), based on standard confocal microscopy extended with an optical (re-scanning) unit that projects the image directly on a CCD-camera. This new microscope has improved lateral resolution and strongly improved sensitivity while maintaining the sectioning capability of a standard confocal microscope. This simple technology is typically useful for biological applications where the combination high-resolution and high-sensitivity is required.

  2. Lidar arc scan uncertainty reduction through scanning geometry optimization

    NASA Astrophysics Data System (ADS)

    Wang, H.; Barthelmie, R. J.; Pryor, S. C.; Brown, G.

    2015-10-01

    Doppler lidars are frequently operated in a mode referred to as arc scans, wherein the lidar beam scans across a sector with a fixed elevation angle and the resulting measurements are used to derive an estimate of the n minute horizontal mean wind velocity (speed and direction). Previous studies have shown that the uncertainty in the measured wind speed originates from turbulent wind fluctuations and depends on the scan geometry (the arc span and the arc orientation). This paper is designed to provide guidance on optimal scan geometries for two key applications in the wind energy industry: wind turbine power performance analysis and annual energy production. We present a quantitative analysis of the retrieved wind speed uncertainty derived using a theoretical model with the assumption of isotropic and frozen turbulence, and observations from three sites that are onshore with flat terrain, onshore with complex terrain and offshore, respectively. The results from both the theoretical model and observations show that the uncertainty is scaled with the turbulence intensity such that the relative standard error on the 10 min mean wind speed is about 30 % of the turbulence intensity. The uncertainty in both retrieved wind speeds and derived wind energy production estimates can be reduced by aligning lidar beams with the dominant wind direction, increasing the arc span and lowering the number of beams per arc scan. Large arc spans should be used at sites with high turbulence intensity and/or large wind direction variation when arc scans are used for wind resource assessment.

  3. Experimental tomographic scanning (TOSCA) imagers

    NASA Astrophysics Data System (ADS)

    Hovland, H.

    2014-06-01

    The tomographic scanner (TOSCA) detects signals using line detectors scanning a scene at regularly distributed angles. These line scan signals are then processed to reconstruct 2-dimensional images. In the simplest form, a 1-axis rotating conical scan optics scans across a simple patterned reticle, the signal collection being done with a single pixel detector. Experimental mono- and multispectral cameras using this approach are demonstrated under varying illumination conditions. Of particular interest is the TOSCA system's ability to handle and compensate for light sources modulated with a frequency higher than that of the frame rate. We also demonstrate for the first time a TOSCA imager operating in the infrared region. The device is put together using 3D-printed key parts and low cost optical components, leading to a very economical infrared camera.

  4. Transverse section radionuclide scanning system

    DOEpatents

    Kuhl, David E.; Edwards, Roy Q.

    1976-01-01

    This invention provides a transverse section radionuclide scanning system for high-sensitivity quantification of brain radioactivity in cross-section picture format in order to permit accurate assessment of regional brain function localized in three-dimensions. High sensitivity crucially depends on overcoming the heretofore known raster type scanning, which requires back and forth detector movement involving dead-time or partial enclosure of the scan field. Accordingly, this invention provides a detector array having no back and forth movement by interlaced detectors that enclose the scan field and rotate as an integral unit around one axis of rotation in a slip ring that continuously transmits the detector data by means of laser emitting diodes, with the advantages that increased amounts of data can be continuously collected, processed and displayed with increased sensitivity according to a suitable computer program.

  5. Scans as primitive parallel operations

    SciTech Connect

    Blelloch, G.E. . Dept. of Computer Science)

    1989-11-01

    In most parallel random access machine (PRAM) models, memory references are assumed to take unit time. In practice, and in theory, certain scan operations, also known as prefix computations, can execute in no more time than these parallel memory references. This paper outlines an extensive study of the effect of including, in the PRAM models, such scan operations as unit-time primitives. The study concludes that the primitives improve the asymptotic running time of many algorithms by an O(log n) factor greatly simplify the description of many algorithms, and are significantly easier to implement than memory references. The authors argue that the algorithm designer should feel free to use these operations as if they were as cheap as a memory reference. This paper describes five algorithms that clearly illustrate how the scan primitives can be used in algorithm design. These all run on an EREW PRAM with the addition of two scan primitives.

  6. Eddy current scanning at Fermilab

    SciTech Connect

    Boffo, C.; Bauer, P.; Foley, M.; Brinkmann, A.; Ozelis, J.; /Jefferson Lab

    2005-07-01

    In the framework of SRF cavity development, Fermilab is creating the infrastructure needed for the characterization of the material used in the cavity fabrication. An important step in the characterization of ''as received'' niobium sheets is the eddy current scanning. Eddy current scanning is a non-destructive technique first adopted and further developed by DESY with the purpose of checking the cavity material for sub-surface defects and inclusions. Fermilab has received and further upgraded a commercial eddy current scanner previously used for the SNS project. The upgrading process included developing new filtering software. This scanner is now used daily to scan the niobium sheets for the Fermilab third harmonic and transverse deflecting cavities. This paper gives a status report on the scanning results obtained so far, including a discussion of the typology of signals being detected. We also report on the efforts to calibrate this scanner, a work conducted in collaboration with DESY.

  7. 3D light scanning macrography.

    PubMed

    Huber, D; Keller, M; Robert, D

    2001-08-01

    The technique of 3D light scanning macrography permits the non-invasive surface scanning of small specimens at magnifications up to 200x. Obviating both the problem of limited depth of field inherent to conventional close-up macrophotography and the metallic coating required by scanning electron microscopy, 3D light scanning macrography provides three-dimensional digital images of intact specimens without the loss of colour, texture and transparency information. This newly developed technique offers a versatile, portable and cost-efficient method for the non-invasive digital and photographic documentation of small objects. Computer controlled device operation and digital image acquisition facilitate fast and accurate quantitative morphometric investigations, and the technique offers a broad field of research and educational applications in biological, medical and materials sciences. PMID:11489078

  8. Lidar arc scan uncertainty reduction through scanning geometry optimization

    NASA Astrophysics Data System (ADS)

    Wang, Hui; Barthelmie, Rebecca J.; Pryor, Sara C.; Brown, Gareth.

    2016-04-01

    Doppler lidars are frequently operated in a mode referred to as arc scans, wherein the lidar beam scans across a sector with a fixed elevation angle and the resulting measurements are used to derive an estimate of the n minute horizontal mean wind velocity (speed and direction). Previous studies have shown that the uncertainty in the measured wind speed originates from turbulent wind fluctuations and depends on the scan geometry (the arc span and the arc orientation). This paper is designed to provide guidance on optimal scan geometries for two key applications in the wind energy industry: wind turbine power performance analysis and annual energy production prediction. We present a quantitative analysis of the retrieved wind speed uncertainty derived using a theoretical model with the assumption of isotropic and frozen turbulence, and observations from three sites that are onshore with flat terrain, onshore with complex terrain and offshore, respectively. The results from both the theoretical model and observations show that the uncertainty is scaled with the turbulence intensity such that the relative standard error on the 10 min mean wind speed is about 30 % of the turbulence intensity. The uncertainty in both retrieved wind speeds and derived wind energy production estimates can be reduced by aligning lidar beams with the dominant wind direction, increasing the arc span and lowering the number of beams per arc scan. Large arc spans should be used at sites with high turbulence intensity and/or large wind direction variation.

  9. The frequency of low muscle mass and its overlap with low bone mineral density and lipodystrophy in individuals with HIV--a pilot study using DXA total body composition analysis.

    PubMed

    Buehring, Bjoern; Kirchner, Elizabeth; Sun, Zhiyuan; Calabrese, Leonard

    2012-01-01

    As a result of the advances in antiretroviral therapy, the life span of human immunodeficiency virus (HIV)-infected patients has increased dramatically. Attendant to these effects are signs of premature aging with notable changes in the musculoskeletal system. Although changes in bone and fat distribution have been studied extensively, far less is known about changes in muscle. This study examined the extent of low muscle mass (LMM) and its relationship with low bone mineral density (BMD) and lipodystrophy (LD) in HIV-positive males. As such, HIV-positive males on therapy or treatment naive underwent dual-energy X-ray absorptiometry total body composition measurements. Appendicular lean mass/(height)2 and lowest 20% of residuals from regression analysis were used to define LMM. BMD criteria defined osteopenia/osteoporosis, and the percent central fat/percent lower extremity ratio defined LD. Several potential risk factors were assessed through chart review. Sixty-six males (57 with treatment and 9 treatment naive) volunteered. Treated individuals were older than naive (44 vs 34 yr) and had HIV longer (108 vs 14 mo). When definitions for sarcopenia (SP) in elderly individuals were applied, the prevalence of LMM was 21.9% and 18.8% depending on the definition used. Low BMD was present in 68.2% of participants. LD with a cutoff of 1.5 and 1.961 was present in 54.7% and 42.2% of participants, respectively. LMM and LD were negatively associated. In conclusion, this study shows that LMM is common in males with HIV and that SP affecting muscle function could be present in a substantial number of individuals. Future research needs to examine what impact decreased muscle mass and function has on morbidity, physical function, and quality of life in individuals with HIV. PMID:22169198

  10. Body shape and size in 6-year old children: assessment by three-dimensional photonic scanning

    PubMed Central

    Santos, L P; Ong, K K; Day, F; Wells, J C K; Matijasevich, A; Santos, I S; Victora, C G; Barros, A J D

    2016-01-01

    Background: Body shape and size are typically described using measures such as body mass index (BMI) and waist circumference, which predict disease risks in adults. However, this approach may underestimate the true variability in childhood body shape and size. Objective: To use a comprehensive three-dimensional photonic scan approach to describe variation in childhood body shape and size. Subjects/Methods: At age 6 years, 3350 children from the population-based 2004 Pelotas birth cohort study were assessed by three-dimensional photonic scanner, traditional anthropometry and dual X-ray absorptiometry. Principal component analysis (PCA) was performed on height and 24 photonic scan variables (circumferences, lengths/widths, volumes and surface areas). Results: PCA identified four independent components of children's body shape and size, which we termed: Corpulence, Central:peripheral ratio, Height and arm lengths, and Shoulder diameter. Corpulence showed strong correlations with traditional anthropometric and body composition measures (r>0.90 with weight, BMI, waist circumference and fat mass; r>0.70 with height, lean mass and bone mass); in contrast, the other three components showed weak or moderate correlations with those measures (all r<0.45). There was no sex difference in Corpulence, but boys had higher Central:peripheral ratio, Height and arm lengths and Shoulder diameter values than girls. Furthermore, children with low birth weight had lower Corpulence and Height and arm lengths but higher Central:peripheral ratio and Shoulder diameter than other children. Children from high socio-economic position (SEP) families had higher Corpulence and Height and arm lengths than other children. Finally, white children had higher Corpulence and Central:peripheral ratio than mixed or black children. Conclusions: Comprehensive assessment by three-dimensional photonic scanning identified components of childhood body shape and size not captured by traditional anthropometry or

  11. Environmental Scanning and the Information Manager.

    ERIC Educational Resources Information Center

    Newsome, James; McInerney, Claire

    1990-01-01

    Discusses nine components of an environmental scanning model: selecting the scanning team; selecting resources to scan; choosing criteria for scanning; scanning the resources; identifying signals of new issues; selecting key events/issues; monitoring and analyzing events/issues; disseminating information; and deciding on appropriate organizational…

  12. Electronic scanning of 2-channel monopulse patterns

    NASA Technical Reports Server (NTRS)

    Schmidt, R. F.

    1970-01-01

    Scanning method involves separation of scanning capability into two independent degrees of freedom. One degree of freedom corresponds to azimuthal scanning and other to elevation scanning on spiral coordinate axes. Scanning of both prime-feed and mirrored patterns is accomplished with reduction of mechanical vibration damage to large antennas.

  13. Scanning laser polarimetry - a review.

    PubMed

    Da Pozzo, Stefano; Marchesan, Roberta; Ravalico, Giuseppe

    2009-01-01

    Glaucoma is a leading cause of irreversible blindness worldwide. Retinal ganglion cells and their axons represent the selective target of the disease. When visual function is still intact on standard automated perimetry and optic disc appearance is suspicious, an early diagnosis may be supported by the identification of a retinal nerve fibre layer (RNFL) defect in the peripapillary area. At present days, computer-based, real-time imaging of the peripapillary RNFL is available through instruments of easy use and with high levels of accuracy and reproducibility. Scanning laser polarimetry is performed by a confocal scanning laser ophthalmoscope with an integrated polarimeter (GDx-VCC). There is a considerable amount of scientific evidence about the role of this imaging technique for glaucoma diagnosis. The aim of this review is to describe the principles of operation, the examination procedure, the clinical role, the results of main diagnostic studies and the future development of the software for the scanning laser polarimetry. PMID:19138311

  14. Scanning Terahertz Heterodyne Imaging Systems

    NASA Technical Reports Server (NTRS)

    Siegel, Peter; Dengler, Robert

    2007-01-01

    Scanning terahertz heterodyne imaging systems are now at an early stage of development. In a basic scanning terahertz heterodyne imaging system, (see Figure 1) two far-infrared lasers generate beams denoted the local-oscillator (LO) and signal that differ in frequency by an amount, denoted the intermediate frequency (IF), chosen to suit the application. The LO beam is sent directly to a mixer as one of two inputs. The signal beam is focused to a spot on or in the specimen. After transmission through or reflection from the specimen, the beams are focused to a spot on a terahertz mixer, which extracts the IF outputs. The specimen is mounted on a translation stage, by means of which the focal spot is scanned across the specimen to build up an image.

  15. Spiral scan peripheral nerve stimulation.

    PubMed

    King, K F; Schaefer, D J

    2000-07-01

    Time-varying magnetic fields induce electric fields that can cause physiological stimulation. Stimulation has been empirically characterized as a function of dB/dt and duration based on experiments using trapezoidal and sinusoidal gradient waveforms with constant ramp time, amplitude, and direction. For two-dimensional (2D) spiral scans, the readout gradient waveforms are frequency- and amplitude-modulated sinusoids on two orthogonal axes in quadrature. The readout gradient waveform therefore rotates with amplitude and angular velocity that are generally not constant. It does not automatically follow that spiral stimulation thresholds can be predicted using available stimulation models. We scanned 18 normal volunteers with a 2D spiral scan and measured global thresholds for axial, sagittal, and coronal planes. We concluded that the stimulation model evaluated accurately predicts slew rate-limited spiral mean stimulation thresholds, if the effective ramp time is chosen to be the half-period at the end of the spiral readout.

  16. A novel digital scanning microscope

    NASA Astrophysics Data System (ADS)

    Lyu, Hong-Chou; Yu, Hsing-Cheng; Cheng, Kuen-Chiuan; Lee, Yuan-Chin; Ju, Jau-Jiu

    2011-06-01

    A novel digital scanning microscope (DSM) for observing cellular fluorescent micro-images is proposed and manufactured in this study. DSM applied in the biomedical field has been designed based on a concept of fast access time of an optical pick-up head (PUH) in optical disc devices; hence, DSM has been developed based on a blue-ray PUH module with a triaxial scanning actuator (TSA) system. High-resolution and high-speed scanning is effectively realized by TSA system instead of utilizing high-precision transpose stage mechanism. In consequent, a PUH module can work with a time-correlated single photon counting (TCSPC) module and serve as DSM for detecting fluorescent signals on samples.

  17. What Is a Nuclear Heart Scan?

    MedlinePlus

    ... from the NHLBI on Twitter. What Is a Nuclear Heart Scan? A nuclear heart scan is a test that provides important ... use it to create pictures of your heart. Nuclear heart scans are used for three main purposes: ...

  18. Spin scan imaging at Jupiter

    NASA Technical Reports Server (NTRS)

    Sinclair, K. F.

    1973-01-01

    The general feasibility of spin scan imaging from spinning platforms in outer planet orbiters was investigated. The study was limited to consideration of a typical orbiter mission to Jupiter with an orbit designed to provide repetitive close approaches to the Galilean satellites. Discussed are: (1) data requirements for imaging experiments at Jupiter and its satellites; (2) spin scan camera and baseline camera selection; and (3) operational considerations bearing on imager performance. A physical camera model including relationships identifying the supporting requirements was developed and used to determine the characteristics of the baseline camera.

  19. Scanning color optical tomography (SCOT)

    PubMed Central

    Hosseini, Poorya; Sung, Yongjin; Choi, Youngwoon; Lue, Niyom; Yaqoob, Zahid; So, Peter

    2015-01-01

    We have developed an interferometric optical microscope that provides three-dimensional refractive index map of a specimen by scanning the color of three illumination beams. Our design of the interferometer allows for simultaneous measurement of the scattered fields (both amplitude and phase) of such a complex input beam. By obviating the need for mechanical scanning of the illumination beam or detection objective lens; the proposed method can increase the speed of the optical tomography by orders of magnitude. We demonstrate our method using polystyrene beads of known refractive index value and live cells. PMID:26367632

  20. Conically scanned holographic lidar telescope

    NASA Technical Reports Server (NTRS)

    Schwemmer, Geary (Inventor)

    1993-01-01

    An optical scanning device utilizing a source of optical energy such as laser light backscattered from the earth's atmosphere or transmitted outward as in a lidar, a rotating holographic optical element having an axis of rotation perpendicular to the plane of its substrate, and having a stationary focus which may or may not be located on its axis of rotation, with the holographic optical element diffracting the source of optical energy at an angle to its rotation axis enabling a conical scanning area and a motor for supporting and rotating the rotating holographic optical element, is described.

  1. Scanning color optical tomography (SCOT).

    PubMed

    Hosseini, Poorya; Sung, Yongjin; Choi, Youngwoon; Lue, Niyom; Yaqoob, Zahid; So, Peter

    2015-07-27

    We have developed an interferometric optical microscope that provides three-dimensional refractive index map of a specimen by scanning the color of three illumination beams. Our design of the interferometer allows for simultaneous measurement of the scattered fields (both amplitude and phase) of such a complex input beam. By obviating the need for mechanical scanning of the illumination beam or detection objective lens; the proposed method can increase the speed of the optical tomography by orders of magnitude. We demonstrate our method using polystyrene beads of known refractive index value and live cells. PMID:26367632

  2. Lidar arc scan uncertainty reduction through scanning geometry optimization

    DOE PAGES

    Wang, Hui; Barthelmie, Rebecca J.; Pryor, Sara C.; Brown, Gareth.

    2016-04-13

    Doppler lidars are frequently operated in a mode referred to as arc scans, wherein the lidar beam scans across a sector with a fixed elevation angle and the resulting measurements are used to derive an estimate of the n minute horizontal mean wind velocity (speed and direction). Previous studies have shown that the uncertainty in the measured wind speed originates from turbulent wind fluctuations and depends on the scan geometry (the arc span and the arc orientation). This paper is designed to provide guidance on optimal scan geometries for two key applications in the wind energy industry: wind turbine power performance analysis and annualmore » energy production prediction. We present a quantitative analysis of the retrieved wind speed uncertainty derived using a theoretical model with the assumption of isotropic and frozen turbulence, and observations from three sites that are onshore with flat terrain, onshore with complex terrain and offshore, respectively. The results from both the theoretical model and observations show that the uncertainty is scaled with the turbulence intensity such that the relative standard error on the 10 min mean wind speed is about 30 % of the turbulence intensity. The uncertainty in both retrieved wind speeds and derived wind energy production estimates can be reduced by aligning lidar beams with the dominant wind direction, increasing the arc span and lowering the number of beams per arc scan. Large arc spans should be used at sites with high turbulence intensity and/or large wind direction variation.« less

  3. Infrared Scanning For Electrical Maintenance

    NASA Astrophysics Data System (ADS)

    Eisenbath, Steven E.

    1983-03-01

    Given the technological age that we have now entered, the purpose of this paper is to relate how infrared scanning can be used for an electrical preventative maintenance program. An infrared scanner is able to produce an image because objects give off infrared radiation in relationship to their temperature. Most electrical problems will show up as an increase in temperature, thereby making the infrared scanner a useful preventative maintenance tool. Because of the sensitivity of most of the scanners, .1 to .2 of a degree, virtually all electrical problems can be pinpointed long before they become a costly failure. One of the early uses of infrared scanning was to check the power company's electrical distribution system. Most of this was performed via aircraft or truck mounted scanning devices which necessitated its semi-permanent mounting. With the advent of small hand held infrared imagers, along with more portability of the larger systems, infrared scanning has gained more popularity in checking electrical distribution systems. But the distribution systems are now a scaled down model, mainly the in-plant electrical systems. By in-plant, I mean any distribution of electricity; once it leaves the power company's grid. This can be in a hospital, retail outlet, warehouse or manufacturing facility.

  4. Scanning tunneling microscope nanoetching method

    DOEpatents

    Li, Yun-Zhong; Reifenberger, Ronald G.; Andres, Ronald P.

    1990-01-01

    A method is described for forming uniform nanometer sized depressions on the surface of a conducting substrate. A tunneling tip is used to apply tunneling current density sufficient to vaporize a localized area of the substrate surface. The resulting depressions or craters in the substrate surface can be formed in information encoding patterns readable with a scanning tunneling microscope.

  5. Technical aspects of CT scanning.

    PubMed

    Maravilla, K R; Pastel, M S

    1978-01-01

    The advent of computed tomography (CT) has initiated a technological revolution which continues to the present time. A brief review of basic principles of CT scanning is presented, and the evolution of modern CT scanner systems is traced. Some early indications of future trends are also presented.

  6. Environmental Scanning, Vancouver Community College.

    ERIC Educational Resources Information Center

    Yao, Min

    This 1994 environmental scanning report from Vancouver Community College (VCC) reviews the expected effects of the separation of VCC into a new Vancouver Community College and Langara College (LC). The report examines the projected service area student-intake capacity; student characteristics; population growth trends; other postsecondary…

  7. Improvement of CAT scanned images

    NASA Technical Reports Server (NTRS)

    Roberts, E., Jr.

    1980-01-01

    Digital enhancement procedure improves definition of images. Tomogram is generated from large number of X-ray beams. Beams are collimated and small in diameter. Scanning device passes beams sequentially through human subject at many different angles. Battery of transducers opposite subject senses attenuated signals. Signals are transmitted to computer where they are used in construction of image on transverse plane through body.

  8. Line-scanning laser ophthalmoscope

    NASA Astrophysics Data System (ADS)

    Hammer, Daniel X.; Ferguson, R. Daniel; Ustun, Teoman E.; Bigelow, Chad E.; Iftimia, Nicusor V.; Webb, Robert H.

    2006-07-01

    Scanning laser ophthalmoscopy (SLO) is a powerful imaging tool with specialized applications limited to research and ophthalmology clinics due in part to instrument size, cost, and complexity. Conversely, low-cost retinal imaging devices have limited capabilities in screening, detection, and diagnosis of diseases. To fill the niche between these two, a hand-held, nonmydriatic line-scanning laser ophthalmoscope (LSLO) is designed, constructed, and tested on normal human subjects. The LSLO has only one moving part and uses a novel optical approach to produce wide-field confocal fundus images. Imaging modes include multiwavelength illumination and live stereoscopic imaging with a split aperture. Image processing and display functions are controlled with two stacked prototype compact printed circuit boards. With near shot-noise limited performance, the digital LSLO camera requires low illumination power (<500 µW) at near-infrared wavelengths. The line-scanning principle of operation is examined in comparison to SLO and other imaging modes. The line-scanning approach produces high-contrast confocal images with nearly the same performance as a flying-spot SLO. The LSLO may significantly enhance SLO utility for routine use by ophthalmologists, optometrists, general practitioners, and also emergency medical personnel and technicians in the field for retinal disease detection and other diverse applications.

  9. A CAT scan for cells

    SciTech Connect

    2009-01-01

    Recently, a team of scientists from Berkeley Lab, Stanford University, and the University of California, San Francisco used Berkeley Lab's National Center for X-ray Tomography to capture the changes that occur when Candida albicans is exposed to a new and promising antifungal therapy. http://newscenter.lbl.gov/feature-stories/2009/12/10/cat-scan-cells/

  10. Children, CT Scan and Radiation

    PubMed Central

    Bajoghli, Morteza; Bajoghli, Farshad; Tayari, Nazila; Rouzbahani, Reza

    2010-01-01

    Children are more sensitive to radiation than adults. Computerized tomography (CT) consists of 25 % of all medical imaging. It was estimated that more than 2% of all carcinomas in the USA are due to CT scans. There is an ongoing focus on the reduction of CT scan radiation dose. Awareness about risk-benefits of CT has increased. Reduction of radiological exam is an important issue because the accumulation effects of radiation can be hazardous. In addition, proper protocol should be followed for diagnostic procedures of ionization radiation and computerized tomography. Effective radiation dose should range from 0.8 to 10.5 millisievert. The same protocol should be followed in different hospitals as well. Basic principles of radiation protection should be monitored. As much as possible, both technician and radiologist must be present during computerized tomography for children, and MRI and ultrasound should be replaced if possible. PMID:21566776

  11. Vertically scanned laser sheet microscopy.

    PubMed

    Dong, Di; Arranz, Alicia; Zhu, Shouping; Yang, Yujie; Shi, Liangliang; Wang, Jun; Shen, Chen; Tian, Jie; Ripoll, Jorge

    2014-01-01

    Laser sheet microscopy is a widely used imaging technique for imaging the three-dimensional distribution of a fluorescence signal in fixed tissue or small organisms. In laser sheet microscopy, the stripe artifacts caused by high absorption or high scattering structures are very common, greatly affecting image quality. To solve this problem, we report here a two-step procedure which consists of continuously acquiring laser sheet images while vertically displacing the sample, and then using the variational stationary noise remover (VSNR) method to further reduce the remaining stripes. Images from a cleared murine colon acquired with a vertical scan are compared with common stitching procedures demonstrating that vertically scanned light sheet microscopy greatly improves the performance of current light sheet microscopy approaches without the need for complex changes to the imaging setup and allows imaging of elongated samples, extending the field of view in the vertical direction.

  12. Scanning phononic lattices with ultrasound

    SciTech Connect

    Vines, R.E.; Wolfe, J.P.; Every, A.V.

    1999-11-01

    A method for probing the elastic properties of newly developed periodic structures using acoustic waves is introduced. Highly anisotropic transmission of surface acoustic waves is observed by continuously scanning the wave vector angle. Preliminary models of wave propagation through multilayers and two-dimensional lattices explain some of the experimental features, while other features can be attributed to the resonant excitation of interface waves. {copyright} {ital 1999} {ital The American Physical Society}

  13. Cloud Top Scanning radiometer (CTS)

    NASA Technical Reports Server (NTRS)

    1978-01-01

    A scanning radiometer to be used for measuring cloud radiances in each of three spectral regions is described. Significant features incorporated in the Cloud Top Scanner design are: (1) flexibility and growth potential through use of easily replaceable modular detectors and filters; (2) full aperture, multilevel inflight calibration; (3) inherent channel registration through employment of a single shared field stop; and (4) radiometric sensitivity margin in a compact optical design through use of Honeywell developed (Hg,Cd)Te detectors and preamplifiers.

  14. Differential scanning calorimetry of coal

    NASA Technical Reports Server (NTRS)

    Gold, P. I.

    1978-01-01

    Differential scanning calorimetry studies performed during the first year of this project demonstrated the occurrence of exothermic reactions associated with the production of volatile matter in or near the plastic region. The temperature and magnitude of the exothermic peak were observed to be strongly affected by the heating rate, sample mass and, to a lesser extent, by sample particle size. Thermal properties also were found to be influenced by oxidation of the coal sample due to weathering effects.

  15. Mechanically scanned deployable antenna study

    NASA Astrophysics Data System (ADS)

    1983-03-01

    The conceptual design of a Mechanically Scanned Deployable Antenna which is launched by the STS (Space Shuttle) to provide radiometric brightness temperature maps of the Earth and oceans at selected frequency bands in the frequency range of 1.4 GHz to 11 GHz is presented. Unlike previous scanning radiometric systems, multiple radiometers for each frequency are required in order to fill in the resolution cells across the swath created by the 15 meter diameter spin stabilized system. This multiple beam radiometric system is sometimes designated as a ""whiskbroom'' system in that it combines the techniques of the scanning and ""pushbroom'' type systems. The definition of the feed system including possible feed elements and location, determination of the fundamental reflector feed offset geometry including offset angles and f/D ratio, preliminary estimates of the beam efficiency of the feed reflector system, a summary of reflector mesh losses at the proposed radiometric frequency bands, an overall conceptual configuration design and preliminary structural and thermal analyses are included.

  16. Mechanically scanned deployable antenna study

    NASA Technical Reports Server (NTRS)

    1983-01-01

    The conceptual design of a Mechanically Scanned Deployable Antenna which is launched by the STS (Space Shuttle) to provide radiometric brightness temperature maps of the Earth and oceans at selected frequency bands in the frequency range of 1.4 GHz to 11 GHz is presented. Unlike previous scanning radiometric systems, multiple radiometers for each frequency are required in order to fill in the resolution cells across the swath created by the 15 meter diameter spin stabilized system. This multiple beam radiometric system is sometimes designated as a ""whiskbroom'' system in that it combines the techniques of the scanning and ""pushbroom'' type systems. The definition of the feed system including possible feed elements and location, determination of the fundamental reflector feed offset geometry including offset angles and f/D ratio, preliminary estimates of the beam efficiency of the feed reflector system, a summary of reflector mesh losses at the proposed radiometric frequency bands, an overall conceptual configuration design and preliminary structural and thermal analyses are included.

  17. Preoperative nuclear scans in patients with melanoma

    SciTech Connect

    Au, F.C.; Maier, W.P.; Malmud, L.S.; Goldman, L.I.; Clark, W.H. Jr.

    1984-05-15

    One hundred forty-one liver scans, 137 brain scans, and 112 bone scans were performed in 192 patients with clinical Stage 1 melanoma. One liver scan was interpreted as abnormal; liver biopsy of that patient showed no metastasis. There were 11 suggestive liver scans; three of the patients with suggestive liver scans had negative liver biopsies. The remaining eight patients were followed from 4 to 6 years and none of those patients developed clinical evidence of hepatic metastases. All of the brain scans were normal. Five patients had suggestive bone scans and none of those patients had manifested symptoms of osseous metastases with a follow-up of 2 to 4.5 years. This study demonstrates that the use of preoperative liver, brain and bone scan in the evaluation of patients with clinical Stage 1 melanoma is virtually unproductive.

  18. Scanning tunneling and scanning transmission electron microscopy of biological membranes

    NASA Astrophysics Data System (ADS)

    Stemmer, A.; Reichelt, R.; Engel, A.; Rosenbusch, J. P.; Ringger, M.; Hidber, H. R.; Güntherodt, H. J.

    1987-03-01

    The feasibility of imaging porin membrane, which is a reconstituted biological membrane consisting of phospholipid and protein, was studied by scanning tunneling microscopy (STM). Due to detailed knowledge of its composition from biochemical and its three-dimensional (3D) structure from electron microscopical analysis, porin vesicles seem to be a suitable model specimen for exploring the application of STM in biology. Unstained vesicles adsorbed onto a thin amorphous carbon film supported by a finder grid were localized using a scanning transmission electron microscope (STEM) at low irradiation doses ( < 100 {e -}/{nm 2}). Suitable areas of the sample were then positioned in the STM by a light optical telescope. STM images taken under ambient pressure from empty amorphous carbon films exhibited corrugations in the range of ⩽ 1 nm, whereas steps having a height of 5 nm were reproducibly observed on grids with porin vesicles. Since this value is in good agreement with that obtained from air-dried metal shadowed vesicles, we interpret these steps as the edges of porin membranes.

  19. Aperture scanning Fourier ptychographic microscopy

    PubMed Central

    Ou, Xiaoze; Chung, Jaebum; Horstmeyer, Roarke; Yang, Changhuei

    2016-01-01

    Fourier ptychographic microscopy (FPM) is implemented through aperture scanning by an LCOS spatial light modulator at the back focal plane of the objective lens. This FPM configuration enables the capturing of the complex scattered field for a 3D sample both in the transmissive mode and the reflective mode. We further show that by combining with the compressive sensing theory, the reconstructed 2D complex scattered field can be used to recover the 3D sample scattering density. This implementation expands the scope of application for FPM and can be beneficial for areas such as tissue imaging and wafer inspection. PMID:27570705

  20. Scanning Miniature Microscopes without Lenses

    NASA Technical Reports Server (NTRS)

    Wang, Yu

    2009-01-01

    The figure schematically depicts some alternative designs of proposed compact, lightweight optoelectronic microscopes that would contain no lenses and would generate magnified video images of specimens. Microscopes of this type were described previously in Miniature Microscope Without Lenses (NPO - 20218), NASA Tech Briefs, Vol. 22, No. 8 (August 1998), page 43 and Reflective Variants of Miniature Microscope Without Lenses (NPO 20610), NASA Tech Briefs, Vol. 26, No. 9 (September 1999), page 6a. To recapitulate: In the design and construction of a microscope of this type, the focusing optics of a conventional microscope are replaced by a combination of a microchannel filter and a charge-coupled-device (CCD) image detector. Elimination of focusing optics reduces the size and weight of the instrument and eliminates the need for the time-consuming focusing operation. The microscopes described in the cited prior articles contained two-dimensional CCDs registered with two-dimensional arrays of microchannels and, as such, were designed to produce full two-dimensional images, without need for scanning. The microscopes of the present proposal would contain one-dimensional (line image) CCDs registered with linear arrays of microchannels. In the operation of such a microscope, one would scan a specimen along a line perpendicular to the array axis (in other words, one would scan in pushbroom fashion). One could then synthesize a full two-dimensional image of the specimen from the line-image data acquired at one-pixel increments of position along the scan. In one of the proposed microscopes, a beam of unpolarized light for illuminating the specimen would enter from the side. This light would be reflected down onto the specimen by a nonpolarizing beam splitter attached to the microchannels at their lower ends. A portion of the light incident on the specimen would be reflected upward, through the beam splitter and along the microchannels, to form an image on the CCD. If the

  1. High Resolution Scanning Reflectarray Antenna

    NASA Technical Reports Server (NTRS)

    Romanofsky, Robert R. (Inventor); Miranda, Felix A. (Inventor)

    2000-01-01

    The present invention provides a High Resolution Scanning Reflectarray Antenna (HRSRA) for the purpose of tracking ground terminals and space craft communication applications. The present invention provides an alternative to using gimbaled parabolic dish antennas and direct radiating phased arrays. When compared to a gimbaled parabolic dish, the HRSRA offers the advantages of vibration free steering without incurring appreciable cost or prime power penalties. In addition, it offers full beam steering at a fraction of the cost of direct radiating arrays and is more efficient.

  2. Schistosomiasis collection at NHM (SCAN)

    PubMed Central

    2012-01-01

    Background The Natural History Museum (NHM) is developing a repository for schistosomiasis-related material, the Schistosomiasis Collection at NHM (SCAN) as part of its existing Wolfson Wellcome Biomedical Laboratory (WWBL). This is timely because a major research and evaluation effort to understand control and move towards elimination of schistosomiasis in Africa has been initiated by the Schistosomiasis Consortium for Operational Research and Evaluation (SCORE), resulting in the collection of many important biological samples, including larval schistosomes and snails. SCAN will collaborate with a number of research groups and control teams and the repository will acquire samples relevant to both immediate and future research interest. The samples collected through ongoing research and field activities, WWBL’s existing collections, and other acquisitions will be maintained over the long term and made available to the global research community for approved research purposes. Goals include: · Consolidation of the existing NHM schistosome and snail collections and transfer of specimens into suitable long-term storage systems for DNA retrieval, · Long-term and stable storage of specimens collected as part of on going field programmes initially in Africa especially relating to the SCORE research programmes, · Provision of access to snail and schistosome collections for approved research activities. PMID:22943137

  3. Breast ultrasound scans - surgeons' expectations.

    PubMed

    Bednarski, Piotr; Dobruch-Sobczak, Katarzyna; Chrapowicki, Eryk; Jakubowski, Wiesław

    2015-06-01

    Recent years have witnessed a dynamic development of mammary gland imaging techniques, particularly ultrasonography and magnetic resonance imaging. A challenge related to these studies is the increase in the precision of the anatomical assessment of breast, particularly for early detection of subclinical lesions, performance of ultrasound- guided biopsy procedures, and accurate preoperative location of pathological lesions so as to optimize the surgical treatment. Ultrasound imaging is a primary and baseline diagnostic procedure the patient with suspected pathological lesions within breast is referred to by the surgeon. Lesions visualized in ultrasound scans are classified according to the BI-RADS US assessment categories. The successive categories (2 through 6) encompass individual pathological lesions, estimating the risk of malignancy and provide guidelines for further diagnostic and therapeutic management. This article described the important aspects of ultrasonographic imaging of focal lesions within the breasts as significant from the standpoint of surgical treatment of patients falling within BI-RADS US categories 3, 4, 5, and 6. Attention is drawn to the importance of ultrasound scans in the assessment of axillary fossa lymph nodes before the decision regarding the surgical treatment.

  4. Scanning laser ophthalmoscopy. Clinical applications.

    PubMed

    Mainster, M A; Timberlake, G T; Webb, R H; Hughes, G W

    1982-07-01

    The scanning laser ophthalmoscope (SLO) provides a high-quality television image of the retina using less than 1/1000 of the light required for conventional indirect ophthalmoscopy. The SLO employs a new ophthalmoscopic principle in which a dim laser beam scans across the fundus, and light is collected only from one retinal point at a time. Since the instrument is highly light efficient, illumination levels are comfortable for the patient, and fluorescein angiography can be performed with one tenth of the usual fluorescein dose. Since a continuous, large depth of field view is displayed on the SLO screen and stored on video tape, repeated dynamic inspection of the vitreous, retina and vitreoretinal interface is afforded. In addition, any graphical material that can be displayed on a microcomputer monitor (such as text of video games) can also be impressed on the retinal pattern formed by the sweeping laser beam. The graphical material is thus observed directly by the patient and on the patient's retina by the clinician. Since the exact retinal locus of each point in the graphical material is viewed directly, it is possible to perform perimetry directly on the retina, to measure acuity at arbitrary retinal loci, to study how patients with macular disease use residual functional retina for reading, and to perform distortometry with a retinal (Amsler-type) grid.

  5. Three-dimensional scanning confocal laser microscope

    DOEpatents

    Anderson, R. Rox; Webb, Robert H.; Rajadhyaksha, Milind

    1999-01-01

    A confocal microscope for generating an image of a sample includes a first scanning element for scanning a light beam along a first axis, and a second scanning element for scanning the light beam at a predetermined amplitude along a second axis perpendicular to the first axis. A third scanning element scans the light beam at a predetermined amplitude along a third axis perpendicular to an imaging plane defined by the first and second axes. The second and third scanning element are synchronized to scan at the same frequency. The second and third predetermined amplitudes are percentages of their maximum amplitudes. A selector determines the second and third predetermined amplitudes such that the sum of the percentages is equal to one-hundred percent.

  6. Electronically-Scanned Fourier-Transform Spectrometer

    NASA Technical Reports Server (NTRS)

    Breckinridge, J. B.; Ocallaghan, F. G.

    1984-01-01

    Instrument efficient, lightweight, and stable. Fourier-transform spectrometer configuration uses electronic, instead of mechanical, scanning. Configuration insensitive to vibration-induced sampling errors introduced into mechanically scanned systems.

  7. Preoperative bone quality as a factor in dual-energy X-ray absorptiometry analysis comparing bone remodelling between two implant types

    PubMed Central

    Rahmy, Ali; Grimm, Bernd; Heyligers, Ide; Tonino, Alphons

    2006-01-01

    Recently it was shown that the design changes from the ABG-I to ABG-II hip stem resulted in a better, although not significant, proximal bone preservation. Our hypothesis was that by matching patients for preoperative bone quality, statistical power would increase and that the trend of better proximal bone preservation in ABG-II might become significant. Twenty-four ABG-II patients were compared to two different ABG-I groups: (1) 25 patients from our earlier prospective study and (2) a group of 24 patients selected to perfectly match the ABG-II group regarding gender, age and preoperative bone quality. Postoperative changes in periprosthetic bone mineral density (BMD) were quantified at 2 years postoperatively using DEXA scanning. Bone preservation (less BMD loss) was better for the ABG-II than the ABG-I (all two groups) in the proximal zones 1 and 7. In Gruen zone 7, a statistically significant difference was found for group B (p = 0.03). By matching patients for preoperative bone quality and gender, a statistical significant difference was found in proximal bone preservation in favour of ABG-II. In future comparative bone remodelling studies using DEXA, patients should be matched for preoperative bone quality and gender. PMID:17086429

  8. Laser scanning by rotating polarization gratings.

    PubMed

    Zhou, Yuan; Fan, Dapeng; Fan, Shixun; Chen, Ying; Liu, Guangcan

    2016-07-01

    Laser beam scanning can be realized using two independently rotating, inline polarization gratings, termed Risley gratings, in a fashion similar to Risley prisms. The analytical formulas of pointing position as well as their inverse solutions are described. On this basis, the beam scanning is investigated and the performance of scanning imaging is evaluated. It is shown that the scanning function in 1D scanning evolves from a sinusoidal to triangular scan and the duty cycle increases rapidly as the ratio of grating period to wavelength is reduced toward 2. The scan pattern in 2D scanning is determined by the ratio k of the gratings' rotatory frequency. In imaging applications, when k tends toward 1 or -1, the scan pattern becomes dense and is inclined to be spiral or rose-like, respectively, which is desirable for the purpose of enhancing spatial resolution. There is a direct trade-off between spatial resolution and frame rate. The spiral and rose scanning enable multiresolution imaging, providing a preview of the scanned area in a fraction of the overall scan time, which is extremely useful for fast, real-time imaging applications. PMID:27409203

  9. Improving cranial ultrasound scanning strategy in neonates

    PubMed Central

    Bray, Lisa

    2016-01-01

    Cranial ultrasound scans are undertaken in this tertiary neonatal intensive care unit by the doctors within the department. A quality improvement project was undertaken by means of two PDSA cycles to determine adherence to neonatal cranial ultrasound scanning schedule, assess the quality of scan reporting, and formulate a comprehensive guideline outlining best practice. The baseline measurements assessed 93 scans of preterm infants and 9 of term infants. The results of this prompted intradepartmental education (PDSA cycle 1) then creation and implementation of a documentation template, a local guideline, and education via presentations, posters, and email (PDSA cycle 2). These encompassed 77 preterm and 5 term scans. In our baseline measurements, 52% of preterm infant scans and 44% of term infant scans were performed to schedule. Of premature baby scan reports, 75% had the time documented and 92% the name of the scanning doctor. After implementing changes PDSA cycle 2 data showed that 74% of preterm infant scans and all term infant scans were performed according to schedule, with 100% having the doctor's name and time of scan documented. We successfully introduced a guideline and documentation template, improving performance to schedule and documentation in most areas. It remains an ongoing challenge to adhere to basic standards of documentation; a template can assist in achieving this. Rotating trainees may offer insight into areas that could benefit from quality improvement. This enthusiasm can be successfully harnessed to implement changes to improve quality of patient care. PMID:27096095

  10. Scanning laser polarimetry in glaucoma

    PubMed Central

    Dada, Tanuj; Sharma, Reetika; Angmo, Dewang; Sinha, Gautam; Bhartiya, Shibal; Mishra, Sanjay K; Panda, Anita; Sihota, Ramanjit

    2014-01-01

    Glaucoma is an acquired progressive optic neuropathy which is characterized by changes in the optic nerve head and retinal nerve fiber layer (RNFL). White-on-white perimetry is the gold standard for the diagnosis of glaucoma. However, it can detect defects in the visual field only after the loss of as many as 40% of the ganglion cells. Hence, the measurement of RNFL thickness has come up. Optical coherence tomography and scanning laser polarimetry (SLP) are the techniques that utilize the evaluation of RNFL for the evaluation of glaucoma. SLP provides RNFL thickness measurements based upon the birefringence of the retinal ganglion cell axons. We have reviewed the published literature on the use of SLP in glaucoma. This review elucidates the technological principles, recent developments and the role of SLP in the diagnosis and monitoring of glaucomatous optic neuropathy, in the light of scientific evidence so far. PMID:25494244

  11. UAVSAR Active Electronically Scanned Array

    NASA Technical Reports Server (NTRS)

    Sadowy, Gregory, A.; Chamberlain, Neil F.; Zawadzki, Mark S.; Brown, Kyle M.; Fisher, Charles D.; Figueroa, Harry S.; Hamilton, Gary A.; Jones, Cathleen E.; Vorperian, Vatche; Grando, Maurio B.

    2011-01-01

    The Uninhabited Airborne Vehicle Synthetic Aperture Radar (UAVSAR) is a pod-based, L-band (1.26 GHz), repeatpass, interferometric, synthetic aperture radar (InSAR) used for Earth science applications. Repeat-pass interferometric radar measurements from an airborne platform require an antenna that can be steered to maintain the same angle with respect to the flight track over a wide range of aircraft yaw angles. In order to be able to collect repeat-pass InSAR data over a wide range of wind conditions, UAVSAR employs an active electronically scanned array (AESA). During data collection, the UAVSAR flight software continuously reads the aircraft attitude state measured by the Embedded GPS/INS system (EGI) and electronically steers the beam so that it remains perpendicular to the flight track throughout the data collection

  12. Scanning ARM Cloud Radar Handbook

    SciTech Connect

    Widener, K; Bharadwaj, N; Johnson, K

    2012-06-18

    The scanning ARM cloud radar (SACR) is a polarimetric Doppler radar consisting of three different radar designs based on operating frequency. These are designated as follows: (1) X-band SACR (X-SACR); (2) Ka-band SACR (Ka-SACR); and (3) W-band SACR (W-SACR). There are two SACRs on a single pedestal at each site where SACRs are deployed. The selection of the operating frequencies at each deployed site is predominantly determined by atmospheric attenuation at the site. Because RF attenuation increases with atmospheric water vapor content, ARM's Tropical Western Pacific (TWP) sites use the X-/Ka-band frequency pair. The Southern Great Plains (SGP) and North Slope of Alaska (NSA) sites field the Ka-/W-band frequency pair. One ARM Mobile Facility (AMF1) has a Ka/W-SACR and the other (AMF2) has a X/Ka-SACR.

  13. Scanning Electrochemical Microscopy in Neuroscience

    NASA Astrophysics Data System (ADS)

    Schulte, Albert; Nebel, Michaela; Schuhmann, Wolfgang

    2010-07-01

    This article reviews recent work involving the application of scanning electrochemical microscopy (SECM) to the study of individual cultured living cells, with an emphasis on topographical and functional imaging of neuronal and secretory cells of the nervous and endocrine system. The basic principles of biological SECM and associated negative amperometric-feedback and generator/collector-mode SECM imaging are discussed, and successful use of the methodology for screening soft and fragile membranous objects is outlined. The drawbacks of the constant-height mode of probe movement and the benefits of the constant-distance mode of SECM operation are described. Finally, representative examples of constant-height and constant-distance mode SECM on a variety of live cells are highlighted to demonstrate the current status of single-cell SECM in general and of SECM in neuroscience in particular.

  14. Comparison of Gross Body Fat-Water Magnetic Resonance Imaging at 3 Tesla to Dual Energy X-Ray Absorptiometry in Obese Women

    PubMed Central

    Silver, HJ; Niswender, KD; Kullberg, J; Berglund, J; Johansson, L; Bruvold, M; Avison, MJ; Welch, EB.

    2012-01-01

    Improved understanding of how depot-specific adipose tissue mass predisposes to obesity-related comorbidities could yield new insights into the pathogenesis and treatment of obesity as well as metabolic benefits of weight loss. We hypothesized that three-dimensional contiguous “fat-water” MR imaging (FWMRI) covering the majority of a whole-body field of view (FOV) acquired at 3 Tesla (3T) and coupled with automated segmentation and quantification of amount, type and distribution of adipose and lean soft tissue would show great promise in body composition methodology. Precision of adipose and lean soft tissue measurements in body and trunk regions were assessed for 3T FWMRI and compared to DEXA. Anthropometric, FWMRI and DEXA measurements were obtained in twelve women with BMI 30–39.9 kg/m2. Test-retest results found coefficients of variation for FWMRI that were all under 3%: gross body adipose tissue (GBAT) 0.80%, total trunk adipose tissue (TTAT) 2.08%, visceral adipose tissue (VAT) 2.62%, subcutaneous adipose tissue (SAT) 2.11%, gross body lean soft tissue (GBLST) 0.60%, and total trunk lean soft tissue (TTLST) 2.43%. Concordance correlation coefficients between FWMRI and DEXA were 0.978, 0.802, 0.629, and 0.400 for GBAT, TTAT, GBLST and TTLST, respectively. While Bland Altman plots demonstrated agreement between FWMRI and DEXA for GBAT and TTAT, a negative bias existed for GBLST and TTLST measurements. Differences may be explained by the FWMRI FOV length and potential for DEXA to overestimate lean soft tissue. While more development is necessary, the described 3T FWMRI method combined with fully-automated segmentation is fast (<30 minutes total scan and post-processing time), noninvasive, repeatable and cost effective. PMID:23712980

  15. Laser Scanning Applications in Fluvial Geomorphology

    NASA Astrophysics Data System (ADS)

    Alho, P.

    2014-12-01

    During recent decades, the use of high-resolution laser scanning data in fluvial studies has rapidly increased. Airborne laser scanning (ALS) can be used to extensively map riverine topography. Laser scanning data have great potential to improve the effectiveness of topographical data acquisition and the accuracy and resolution of DTMs (Digital Terrain Models) needed in fluvial geomorphology. Airborne Laser Scanning (ALS) is applicable for mapping areas varying from reach to catchment scale and these data are, therefore, particularly suitable, especially for hydraulic modelling, mapping of flood inundation, and the detection of macro-scale fluvial geomorphology. With Terrestrial Laser Scanning (TLS) a spatial resolution of less than 1 mm and a range accuracy of few millimetres can be achieved. Mobile Laser Scanning (MLS) enables a remarkably faster survey approach compared to the conventional TLS method. One of the newest applications of MLS approaches involves a boat/cart/backpack -based mobile mapping system. This set-up includes laser scanning and imaging from a platform moving along a river course or floodplain and may be used to expand the spatial extent of terrestrial scanning. Detailed DTMs derived from laser scanning data can be used to improve the recognition of fluvial landforms, the geometric data of hydraulic modelling, and the estimation of flood inundation extents and the associated fluvial processes. Fluvial environments also offer challenges for the application of laser scanning techniques. Factors such as vegetation cover, terrain undulation, coarse surface materials and water surfaces may distort a laser scanning survey.

  16. Bone scanning in severe external otitis

    SciTech Connect

    Levin, W.J.; Shary, J.H. 3d.; Nichols, L.T.; Lucente, F.E.

    1986-11-01

    Technetium99 Methylene Diphosphate bone scanning has been considered an early valuable tool to diagnose necrotizing progressive malignant external otitis. However, to our knowledge, no formal studies have actually compared bone scans of otherwise young, healthy patients with severe external otitis to scans of patients with clinical presentation of malignant external otitis. Twelve patients with only severe external otitis were studied with Technetium99 Diphosphate and were compared to known cases of malignant otitis. All scans were evaluated by two neuroradiologists with no prior knowledge of the clinical status of the patients. Nine of the 12 patients had positive bone scans with many scans resembling those reported with malignant external otitis. Interestingly, there was no consistent correlation between the severity of clinical presentation and the amount of Technetium uptake. These findings suggest that a positive bone scan alone should not be interpreted as indicative of malignant external otitis.

  17. An Advanced Quantitative Echosound Methodology for Femoral Neck Densitometry.

    PubMed

    Casciaro, Sergio; Peccarisi, Marco; Pisani, Paola; Franchini, Roberto; Greco, Antonio; De Marco, Tommaso; Grimaldi, Antonella; Quarta, Laura; Quarta, Eugenio; Muratore, Maruizio; Conversano, Francesco

    2016-06-01

    The aim of this paper was to investigate the clinical feasibility and the accuracy in femoral neck densitometry of the Osteoporosis Score (O.S.), an ultrasound (US) parameter for osteoporosis diagnosis that has been recently introduced for lumbar spine applications. A total of 377 female patients (aged 61-70 y) underwent both a femoral dual X-ray absorptiometry (DXA) and an echographic scan of the proximal femur. Recruited patients were sub-divided into a reference database used for ultrasound spectral model construction and a study population for repeatability assessments and accuracy evaluations. Echographic images and radiofrequency signals were analyzed through a fully automatic algorithm that performed a series of combined spectral and statistical analyses, providing as a final output the O.S. value of the femoral neck. Assuming DXA as a gold standard reference, the accuracy of O.S.-based diagnoses resulted 94.7%, with k = 0.898 (p < 0.0001). Significant correlations were also found between O.S.-estimated bone mineral density and corresponding DXA values, with r(2) up to 0.79 and root mean square error = 5.9-7.4%. The reported accuracy levels, combined with the proven ease of use and very good measurement repeatability, provide the adopted method with a potential for clinical routine application in osteoporosis diagnosis.

  18. Body Composition, Muscle Quality and Scoliosis in Female Collegiate Gymnasts: A Pilot Study.

    PubMed

    Trexler, E T; Smith-Ryan, A E; Roelofs, E J; Hirsch, K R

    2015-11-01

    Research has demonstrated an elevated prevalence of body weight concerns and scoliosis among female gymnasts. The purpose of the current pilot study was to evaluate the utility of ultrasonography and dual-energy X-ray absorptiometry (DXA) as practical imaging modalities to measure body composition and spinal curvature variables that may correlate with performance in female collegiate gymnasts (n=15). DXA was used to evaluate body composition and lateral spinal curvature, utilizing a modified Ferguson method. Echo intensity (EI) and cross-sectional area (CSA) of the vastus lateralis were determined from a panoramic cross-sectional ultrasound image. For returning athletes (n=9), performance scores from the previous season were averaged to quantify performance. The average performance score was correlated with lean mass of the arms (R=0.714; P=0.03) and right leg (R=0.680; P=0.04). Performance was not correlated with total mass, fat mass or body fat percentage (P>0.10). Scoliosis was identified in 3 of 15 scans (20%). Echo intensity and CSA of the vastus lateralis were inversely correlated with each other (R=-0.637, P=0.01), but not with other measures of body composition or performance. Results suggest that limb LBM may be a determinant of gymnastics performance, and DXA may provide important health and performance-related information for female collegiate gymnasts. PMID:26332905

  19. Are patients with newly diagnosed breast cancer getting appropriate DEXA scans? A District General Hospital experience.

    PubMed

    Dong, Huan; Dayananda, Pete; Preece, Shay-Anne; Carmichael, Amtul

    2015-01-01

    Breast cancer patients are often at high risk of fragility fractures partly due to adjuvant endocrine therapy such as aromatase inhibitors and chemotherapy. Baseline dual energy X-ray absorptiometry (DEXA) scanning is recommended as a standard of care in identifying patients who are at risk so they can be commenced on bone protective therapy. NICE guideline 80 - "Early and locally advanced breast cancer"[1] states that patients with early invasive breast cancer should have a baseline DEXA scan to assess BMD before the commencement of aromatase inhibitor treatment; if patients have treatment-induced menopause or are starting ovarian ablation/suppression therapy. We have audited the performance of a DGH against these guidelines with a target of 100% concordance. During a one year period (April 2012-April 2013), 100 patients with a new diagnosis of breast cancer were selected at random from the hospital coding database. 100 patients were chosen as this was a convenient sample size. We gathered information for these patients using electronic records, letters, and imaging. This showed a poor compliance of 38% against NICE guidelines. This in turn means that patients with low BMD at diagnosis of breast cancer are being under diagnosed and under treated, resulting in increased potential morbidity associated with fragility fractures. The interventions that resulted from this audit were: dissemination of these results to surgical and oncology departments, posters summarising the guidelines put up in breast clinics, and breast MDTs to discuss the need for DEXA scans for patients with breast cancer. A re-audit was performed for patients diagnosed with early, invasive breast cancer in January 2014 where a compliance of 90% was achieved. This represents a huge improvement in compliance from the baseline measure of 38%. In order to show that this improvement could be sustained, two further cycles were performed in February and March 2014, where the compliance was 92% and 100

  20. A 4-compartment model based validation of air displacement plethysmography, dual energy X-ray absorptiometry, skinfold technique & bio-electrical impedance for measuring body fat in Indian adults

    PubMed Central

    Kuriyan, Rebecca; Thomas, Tinku; Ashok, Sangeetha; J, Jayakumar; Kurpad, Anura V.

    2014-01-01

    Background & objectives: Many methods are available for measuring body fat of an individual, each having its own advantages and limitations. The primary objective of the present study was to validate body fat estimates from individual methods using the 4-compartment (4C) model as reference. The second objective was to obtain estimates of hydration of fat free mass (FFM) using the 4C model. Methods: The body fat of 39 adults (19 men and 20 women) aged 20-40 yr was estimated using air displacement plethysmography (ADP), dual energy X-ray absorptiometry (DEXA), 4-skinfold technique and bio-electrical impedance (BIA). Total body water was estimated using isotope dilution method. Results: All the methods underestimated body fat when compared to 4C model, except for DEXA and the mean difference from the reference was lowest for DEXA and ADP. The precision of the fat mass estimated from 4C model using the propagation of error was 0.25 kg, while the mean hydration factor obtained by the 4C model was found to be 0.74 ± 0.02 in the whole group of men and women. Interpretations & conclusion: The results of the present study suggest that DEXA and ADP methods can provide reasonably accurate estimates of body fat, while skinfold and bio-electrical impedance methods require the use of population specific equations. PMID:25027079

  1. Excitation-scanning hyperspectral imaging microscope.

    PubMed

    Favreau, Peter F; Hernandez, Clarissa; Heaster, Tiffany; Alvarez, Diego F; Rich, Thomas C; Prabhat, Prashant; Leavesley, Silas J

    2014-04-01

    Hyperspectral imaging is a versatile tool that has recently been applied to a variety of biomedical applications, notably live-cell and whole-tissue signaling. Traditional hyperspectral imaging approaches filter the fluorescence emission over a broad wavelength range while exciting at a single band. However, these emission-scanning approaches have shown reduced sensitivity due to light attenuation from spectral filtering. Consequently, emission scanning has limited applicability for time-sensitive studies and photosensitive applications. In this work, we have developed an excitation-scanning hyperspectral imaging microscope that overcomes these limitations by providing high transmission with short acquisition times. This is achieved by filtering the fluorescence excitation rather than the emission. We tested the efficacy of the excitation-scanning microscope in a side-by-side comparison with emission scanning for detection of green fluorescent protein (GFP)-expressing endothelial cells in highly autofluorescent lung tissue. Excitation scanning provided higher signal-to-noise characteristics, as well as shorter acquisition times (300  ms/wavelength band with excitation scanning versus 3  s/wavelength band with emission scanning). Excitation scanning also provided higher delineation of nuclear and cell borders, and increased identification of GFP regions in highly autofluorescent tissue. These results demonstrate excitation scanning has utility in a wide range of time-dependent and photosensitive applications. PMID:24727909

  2. Excitation-scanning hyperspectral imaging microscope

    PubMed Central

    Favreau, Peter F.; Hernandez, Clarissa; Heaster, Tiffany; Alvarez, Diego F.; Rich, Thomas C.; Prabhat, Prashant; Leavesley, Silas J.

    2014-01-01

    Abstract. Hyperspectral imaging is a versatile tool that has recently been applied to a variety of biomedical applications, notably live-cell and whole-tissue signaling. Traditional hyperspectral imaging approaches filter the fluorescence emission over a broad wavelength range while exciting at a single band. However, these emission-scanning approaches have shown reduced sensitivity due to light attenuation from spectral filtering. Consequently, emission scanning has limited applicability for time-sensitive studies and photosensitive applications. In this work, we have developed an excitation-scanning hyperspectral imaging microscope that overcomes these limitations by providing high transmission with short acquisition times. This is achieved by filtering the fluorescence excitation rather than the emission. We tested the efficacy of the excitation-scanning microscope in a side-by-side comparison with emission scanning for detection of green fluorescent protein (GFP)-expressing endothelial cells in highly autofluorescent lung tissue. Excitation scanning provided higher signal-to-noise characteristics, as well as shorter acquisition times (300  ms/wavelength band with excitation scanning versus 3  s/wavelength band with emission scanning). Excitation scanning also provided higher delineation of nuclear and cell borders, and increased identification of GFP regions in highly autofluorescent tissue. These results demonstrate excitation scanning has utility in a wide range of time-dependent and photosensitive applications. PMID:24727909

  3. Correcting nonlinear drift distortion of scanning probe and scanning transmission electron microscopies from image pairs with orthogonal scan directions.

    PubMed

    Ophus, Colin; Ciston, Jim; Nelson, Chris T

    2016-03-01

    Unwanted motion of the probe with respect to the sample is a ubiquitous problem in scanning probe and scanning transmission electron microscopies, causing both linear and nonlinear artifacts in experimental images. We have designed a procedure to correct these artifacts by using orthogonal scan pairs to align each measurement line-by-line along the slow scan direction, by fitting contrast variation along the lines. We demonstrate the accuracy of our algorithm on both synthetic and experimental data and provide an implementation of our method.

  4. Correlation-steered scanning for scanning probe microscopes to overcome thermal drift for ultra-long time scanning.

    PubMed

    Zhang, Liansheng; Long, Qian; Liu, Yongbin; Zhang, Jie; Feng, Zhihua

    2016-07-01

    The thermal effect is one of the most important factors that influence the accuracy of nanoscale measurement and the surface topography of samples in scanning probe microscopes (SPMs). We propose a method called correlation-steered scanning, which is capable of overcoming three-dimensional thermal drifts in real time for ultra-long time scanned images. The image is scanned band by band with overlapping parts between adjacent bands. The vertical drift can be considered as linear and can thus be eliminated together with the tilt of the sample by applying the flattening method. Each band is artificially divided into several blocks for conveniently calculating lateral drifts on the basis of the overlapping area of adjacent bands through digital image correlation. The calculated lateral drifts are compensated to steer the scanning of the subsequent blocks, thus ensuring that all bands are parallel to one another. Experimental results proved that images scanned by the proposed method exhibited less distortions than those obtained from the traditional raster scanning method. The nanoscale measurement results based on the image obtained by the proposed method also showed high accuracy, with an error of less than 1.5%. By scanning as many bands as needed, the correlation-steered scanning method can obtain a highly precise SPM image of an ultra-large area.

  5. Disparities in Osteoporosis Screening Between At-Risk African-American and White Women

    PubMed Central

    Miller, Redonda G; Ashar, Bimal H; Cohen, Jennifer; Camp, Melissa; Coombs, Carmen; Johnson, Elizabeth; Schneyer, Christine R

    2005-01-01

    Background Despite a lower prevalence of osteoporosis in African-American women, they remain at risk and experience a greater mortality than white women after sustaining a hip fracture. Lack of recognition of risk factors may occur in African-American women, raising the possibility that disparities in screening practices may exist. Objective To determine whether there is a difference in physician screening for osteoporosis in postmenopausal, at-risk African-American and white women. Methods We conducted a retrospective chart review at an urban academic hospital and a suburban community hospital. Subjects included 205 African-American and white women, age ≥65 years and weight ≤127 pounds, who were seen in Internal Medicine clinics. The main outcome was dual-energy x-ray absorptiometry (DXA) scan referral. We investigated physician and patient factors associated with referral. Secondary outcomes included evidence of discussion of osteoporosis and prescription of medications to prevent osteoporosis. Results Significantly fewer African-American than white women were referred for a DXA scan (OR 0.39%, 95% confidence interval (CI): 0.22 to 0.68). Physicians were also less likely to mention consideration of osteoporosis in medical records (0.27, 0.15 to 0.48) and to recommend calcium and vitamin D supplementation for this population (0.21, 0.11 to 0.37). If referred, African-American women had comparable DXA completion rates when compared with white women. No physician characteristics were significantly associated with DXA referral patterns. Conclusions Our study found a significant disparity in the recommendation for osteoporosis screening for African-American versus white women of similar risk, as well as evidence of disparate osteoporosis prevention and treatment, confirming results of other studies. Future educational and research initiatives should target this inequality. PMID:16117754

  6. Analytical scanning electron microscopy for solid surface.

    PubMed

    Ichinokawa, T

    1989-07-01

    A scanning electron microscope of ultra-high-vacuum (UHV-SEM) with a field emission gun (FEG) is operated at the primary electron energies of from 100 eV to 3 keV. The instrument can form the images that contain information on surface chemical composition, chemical bonding state (electronic structure), and surface crystal structure in a microscopic resolution of several hundred angstroms (A) using the techniques of scanning Auger electron microscope, scanning electron energy loss microscope, and scanning low-energy electron diffraction (LEED) microscope. A scanning tunneling microscope (STM) also has been combined with the SEM in order to obtain the atomic resolution for the solid surface. The instrumentation and examples of their applications are presented both for scanning LEED microscopy and STM.

  7. Data acquisition and control for gamma scanning

    SciTech Connect

    Barnes, B.K.; Murray, A.S.; Quintana, J.N.

    1980-01-01

    A new computer-based data acquisition and control unit has been installed in the Los Alamos Scientific Laboratory (LASL) system for scanning irradiated reactor fuel pins. The scanning mechanism is controlled by a commercial multichannel analyzer via a CAMAC link with an intelligent crate controller. The scanning and control unit consists of three linked LSI-11 computers. The multitasking capability of the commercial operation system allows control decisions to be based upon currently acquiring data.

  8. Radiogallium scan in P. carinii pneumonia

    SciTech Connect

    Parthasarathy, K.L.; Bakshi, S.P.; Bender, M.A.

    1982-02-01

    A gallium scan performed on a patient with fever of unknown origin (FUO) revealed an abnormal uptake of radiotracer in the lungs despite negative chest roentgenographic examination and other routine diagnostic studies. Subsequent lung biopsy results confirmed the presence of Pneumocystis (P.) carinii infection. A repeat gallium scan obtained following appropriate antibiotic therapy was essentially normal. The importance of radiogallium scanning in an immunosuppressed patient with FUO is emphasized.

  9. Ion Implantation with Scanning Probe Alignment

    SciTech Connect

    Persaud, A.; Liddle, J.A.; Schenkel, T.; Bokor, J.; Ivanov, Tzv.; Rangelow, I.W.

    2005-07-12

    We describe a scanning probe instrument which integrates ion beams with the imaging and alignment function of a piezo-resistive scanning probe in high vacuum. The beam passes through several apertures and is finally collimated by a hole in the cantilever of the scanning probe. The ion beam spot size is limited by the size of the last aperture. Highly charged ions are used to show hits of single ions in resist, and we discuss the issues for implantation of single ions.

  10. Selected papers on laser scanning and recording

    NASA Astrophysics Data System (ADS)

    Beiser, L.

    Previously published papers concerned with laser scanning and recording techniques are presented. Subjects treated include laser beam information scanning and recording, laser scanning techniques, system design considerations for laser scanning, laser noise, reliability, resolution, and dynamic range, and optical data storage systems. Consideration is given to the components and media for developing laser scanning and recording systems, in particular the laser, the optics, the scanner, and the storage media. Topics discussed include basic and operational multichannel acoustooptic operation; galvanometer and analog compensations; motor and control systems; angle measurement of scanner by interferometry, preheat-aided laser recording, creating multidimensional scan using a single rotating component, digital techniques in high resolution analog scanning and recording; laser scanning parameters and latitudes in laser xerography; optical video disc technology; focus error detection in optical data storage systems, holographic laser scanners for nonimpact printing; and techniques in optical strobe recording. Laser beam recording, techniques, film recorder systems, laser scanner applicaations, the optimization of printing speed and printout quality of laser beam printers, an internal drum laser scanning plate exposure system, and an ultra-high resolution graphic data terminal are described.

  11. Influence of scanning strategies on the accuracy of digital intraoral scanning systems.

    PubMed

    Ender, A; Mehl, A

    2013-01-01

    The digital intraoral impression is a central part in today's CAD/CAM dentistry. With its possibilities, new treatment options for the patient is provided and the prosthetic workflow is accelerated. Nowadays, the major issue with intraoral scanning systems is to gain more accuracy especially for larger scan areas and to simplify clinical handling for the dentist. The aim of this study was to investigate different scanning strategies regardingtheir accuracy with full arch scans in an in-vitro study design. A reference master model was used for the digital impressions with the Lava COS, the Cerec Bluecam and a powderfree intraoral scanning system, Cadent iTero. The trueness and precision of each scanning protocol was measured. Lava COS provides the a trueness of 45.8 microm with the scanning protocol recommended from the manufacturer. A different scanning protocol shows significantly lower accuracy (trueness +/- 90.2 microm). Cerec Bluecam also benefits from an optimal scanning protocol with a trueness of +/- 23.3 microm compared to +/- 52.5 microm with a standard protocol. The powderfree impression system Cadent iTero shows also a high accurate full-arch scan with a trueness of +/- 35.0 microm and a precision of +/- 30.9 microm. With the current intraoral scanning systems, full arch dental impressions are possible with a high accuracy, if adequate scan strategies are used. The powderfree scanning system provides the same level of accuracy compared to scanning systems with surface pretreatment.

  12. Vertebral shape: automatic measurement with dynamically sequenced active appearance models.

    PubMed

    Roberts, M G; Cootes, T F; Adams, J E

    2005-01-01

    The shape and appearance of vertebrae on lateral dual x-ray absorptiometry (DXA) scans were statistically modelled. The spine was modelled by a sequence of overlapping triplets of vertebrae, using Active Appearance Models (AAMs). To automate vertebral morphometry, the sequence of trained models was matched to previously unseen scans. The dataset includes a significant number of pathologies. A new dynamic ordering algorithm was assessed for the model fitting sequence, using the best quality of fit achieved by multiple sub-model candidates. The accuracy of the search was improved by dynamically imposing the best quality candidate first. The results confirm the feasibility of substantially automating vertebral morphometry measurements even with fractures or noisy images.

  13. A Student-Built Scanning Tunneling Microscope

    ERIC Educational Resources Information Center

    Ekkens, Tom

    2015-01-01

    Many introductory and nanotechnology textbooks discuss the operation of various microscopes including atomic force (AFM), scanning tunneling (STM), and scanning electron microscopes (SEM). In a nanotechnology laboratory class, students frequently utilize microscopes to obtain data without a thought about the detailed operation of the tool itself.…

  14. Live ultrasound volume reconstruction using scout scanning

    PubMed Central

    Meyer, Amelie; Lasso, Andras; Ungi, Tamas; Fichtinger, Gabor

    2015-01-01

    INTRODUCTION Ultrasound-guided interventions often necessitate scanning of deep-seated anatomical structures that may be hard to visualize. Visualization can be improved using reconstructed 3D ultrasound volumes. High-resolution 3D reconstruction of a large area during clinical interventions is challenging if the region of interest is unknown. We propose a two-stage scanning method allowing the user to perform quick low-resolution scouting followed by high-resolution live volume reconstruction. METHODS Scout scanning is accomplished by stacking 2D tracked ultrasound images into a low-resolution volume. Then, within a region of interest defined in the scout scan, live volume reconstruction can be performed by continuous scanning until sufficient image density is achieved. We implemented the workflow as a module of the open-source 3D Slicer application, within the SlicerIGT extension and building on the PLUS toolkit. RESULTS Scout scanning is performed in a few seconds using 3 mm spacing to allow region of interest definition. Live reconstruction parameters are set to provide good image quality (0.5 mm spacing, hole filling enabled) and feedback is given during live scanning by regularly updated display of the reconstructed volume. DISCUSSION Use of scout scanning may allow the physician to identify anatomical structures. Subsequent live volume reconstruction in a region of interest may assist in procedures such as targeting needle interventions or estimating brain shift during surgery. PMID:26005249

  15. Camera Systems Rapidly Scan Large Structures

    NASA Technical Reports Server (NTRS)

    2013-01-01

    Needing a method to quickly scan large structures like an aircraft wing, Langley Research Center developed the line scanning thermography (LST) system. LST works in tandem with a moving infrared camera to capture how a material responds to changes in temperature. Princeton Junction, New Jersey-based MISTRAS Group Inc. now licenses the technology and uses it in power stations and industrial plants.

  16. The white blood cell scan in orthopedics

    SciTech Connect

    Propst-Proctor, S.L.; Dillingham, M.F.; McDougall, I.R.; Goodwin, D.

    1982-08-01

    A new nuclear scanning technique was found more specific for bone, joint, and soft tissue infections than any previously described scanning technique. The leukocyte scan, whereby a patient's own cells are labeled with a radioactive tagging agent (/sup 111/In oxine), can distinguish an active infectious process from other pain-inducing conditions. Ninety-seven /sup 111/In labeled autologous leukocyte scans were performed in 88 patients. The findings in 17 of 40 patients scanned for possible acute osteomyelitis, six of nine for suspected septic arthritis, and six for possible soft tissue infections, were positive. Subsequent clinical courses verified the infectious nature of these processes in all patients. Patients who had chronic osteomyelitis (14), bony metastases (four patients), heterotopic ossification (three), and degenerative arthritis (two) demonstrated negative findings. Of the seven patients scanned for acute long-bone fractures, one demonstrated positive findings. Nine scans demonstrated positive findings without determined causes. The leukocyte scan is a useful addition to the diagnostic tools of the orthopedic surgeon.

  17. Implementing SCANS. Highlight Zone: Research @ Work.

    ERIC Educational Resources Information Center

    Packer, Arnold C.; Brainard, Scott

    Foremost among efforts over the last decade to improve the work-related skills required of all young people to meet the demands of American's workplaces was the Secretary's Commission on Achieving Necessary Skills Commission (SCANS). Integral to SCANS were its three-part foundation (basic skills, thinking skills, and personal qualities) and these…

  18. Live ultrasound volume reconstruction using scout scanning

    NASA Astrophysics Data System (ADS)

    Meyer, Amelie; Lasso, Andras; Ungi, Tamas; Fichtinger, Gabor

    2015-03-01

    Ultrasound-guided interventions often necessitate scanning of deep-seated anatomical structures that may be hard to visualize. Visualization can be improved using reconstructed 3D ultrasound volumes. High-resolution 3D reconstruction of a large area during clinical interventions is challenging if the region of interest is unknown. We propose a two-stage scanning method allowing the user to perform quick low-resolution scouting followed by high-resolution live volume reconstruction. Scout scanning is accomplished by stacking 2D tracked ultrasound images into a low-resolution volume. Then, within a region of interest defined in the scout scan, live volume reconstruction can be performed by continuous scanning until sufficient image density is achieved. We implemented the workflow as a module of the open-source 3D Slicer application, within the SlicerIGT extension and building on the PLUS toolkit. Scout scanning is performed in a few seconds using 3 mm spacing to allow region of interest definition. Live reconstruction parameters are set to provide good image quality (0.5 mm spacing, hole filling enabled) and feedback is given during live scanning by regularly updated display of the reconstructed volume. Use of scout scanning may allow the physician to identify anatomical structures. Subsequent live volume reconstruction in a region of interest may assist in procedures such as targeting needle interventions or estimating brain shift during surgery.

  19. Nuclear Scans - Multiple Languages: MedlinePlus

    MedlinePlus

    ... Bone Scan (Arabic) العربية Bilingual PDF Health Information Translations PET (Positron Emission Tomography) Scan (Arabic) العربية Bilingual PDF Health Information Translations Stress Muga (Arabic) العربية Bilingual PDF Health Information ...

  20. Means for Positioning and Repositioning Scanning Instruments

    NASA Technical Reports Server (NTRS)

    Polites, Michael E. (Inventor); Alhorn, Dean C. (Inventor)

    1996-01-01

    A method is presented for positioning a scanning instrument to point toward the center of the desired scan wherein the scan is achieved by rotating unbalanced masses (RUMs) rotating about fixed axes of rotation relative to and associated with the instrument, the RUMs being supported on drive shafts spaced from the center of the mass of the instrument and rotating 180 degrees out-of-phase with each other and in planes parallel to each other to achieve the scan. The elevation and cross-elevation angles of the instrument are sensed to determine any offset and offset time rate-of-change, and the magnitude and direction are converted to a RUM cycle angular velocity component to be superimposed on the nominal velocity of the RUMs. This RUM angular velocity component modulates the RUM angular velocity to cause the speed of the RUMs to increase and decrease during each revolution to drive the instrument toward the desired center of the scan.

  1. Scanning tunneling microscope assembly, reactor, and system

    SciTech Connect

    Tao, Feng; Salmeron, Miquel; Somorjai, Gabor A

    2014-11-18

    An embodiment of a scanning tunneling microscope (STM) reactor includes a pressure vessel, an STM assembly, and three spring coupling objects. The pressure vessel includes a sealable port, an interior, and an exterior. An embodiment of an STM system includes a vacuum chamber, an STM reactor, and three springs. The three springs couple the STM reactor to the vacuum chamber and are operable to suspend the scanning tunneling microscope reactor within the interior of the vacuum chamber during operation of the STM reactor. An embodiment of an STM assembly includes a coarse displacement arrangement, a piezoelectric fine displacement scanning tube coupled to the coarse displacement arrangement, and a receiver. The piezoelectric fine displacement scanning tube is coupled to the coarse displacement arrangement. The receiver is coupled to the piezoelectric scanning tube and is operable to receive a tip holder, and the tip holder is operable to receive a tip.

  2. Laser beam scanning by rotary mirrors. I. Modeling mirror-scanning devices.

    PubMed

    Li, Y; Katz, J

    1995-10-01

    Avector approach to tracing the path of a laser beam through an optical system containing movable plane mirrors is described, which permits a unified treatment of a number of basic mirror-scanning devices. We show that the scan field produced by the mirror-scanning system is a curved surface with a straight line as its generating element. The cross section of the scan field can be a circle, an ellipse, or a curve in the shape of an egg. Based on this understanding, some advanced topics are addressed, e.g., the relationship between the scan field and the scan pattern, the dependence of the scan pattern on the location and orientation of the observation surface, optical distortions in a scan pattern, spot-size enlargement caused by non-normal incidence of the scan beam on the observation plane, and so on. Design equations and curves are derived for the mirror-scanning devices that most frequently exist in linear and circular scan technology. Part II contains an analysis of the galvanometer-based optical scanner paddle scanner and the regular polygon. In Part III, X-Y scanning systems are studied. PMID:21060488

  3. Evaluation of scanning methodology in bimanual coordination.

    PubMed

    Maslovat, Dana; Bredin, Shannon S D; Chua, Romeo; Franks, Ian M

    2005-07-01

    A major component of a dynamical paradigm involves a "scanning" procedure in an attempt to determine an individual's intrinsic coordination tendencies before learning, as well as subsequent changes in the coordination landscape after practice. The purpose of the present study was to evaluate two methods of the scanning procedure. Scans were performed before and after 75 trials of a 90 degrees bimanual-coordination pattern and were compared with early and late acquisition trials. Four groups of participants performed scanning and acquisition trials using a combination of either concurrent visual feedback in the form of Lissajous figures, paced by an auditory metronome, or visual metronomes in the form of flashing stimuli. Analyses revealed that all groups improved performance of the 90 degrees pattern with practice. As predicted by the theory of practice specificity, scanning via the same method as acquisition appears to be valid. Scanning via Lissajous figures when the acquisition procedure was flashing squares was also found to be valid, but not the opposite condition. Reasons for this unidirectional transfer are given with these results suggesting that the sensitivity of a given scanning method might be influenced by the method of acquiring the coordination pattern.

  4. HEAO-A nominal scanning observation schedule

    NASA Technical Reports Server (NTRS)

    Fishman, G. J.; Stone, R. L.

    1977-01-01

    The HEAO-A observatory, scheduled for launch in late June 1977, will spend most of its orbital lifetime in a scanning mode, spining from 0.03 to 0.1 rpm about an axis aligned with the sun. The dates of availability in the scan band are given for a list of 248 X-ray sources. Celestial maps of source locations and scan planes, and examples of the nighttime elevation of available sources are presented. This document is intended to aid ground-based observers in planning coordinated observations with HEAO-A.

  5. Scanning-Pencil-Beam Radar Scatterometer

    NASA Technical Reports Server (NTRS)

    Long, David G.; Freilich, Michael H.; Leotta, Daniel F.; Noon, Don E.

    1992-01-01

    SCANSCAT conceptual scanning radar scatterometer placed in nearly polar orbit around Earth at altitude of 705 km aboard Spacecraft B of NASA's Earth Observing System. Measures radar backscattering from surface of ocean. Data processed on ground into normalized radar-backscattering cross sections, then processed into velocities of winds near surface of ocean by use of empirical mathematical model of relationship between normalized backscattering cross section, wind vector at scanned spot, and angle of incidence and azimuth angle of radar beam. Accuracy and coverage exceeds those of fan-beam scatterometer. Modified versions of scanning plan useful in laser inspection of surface finishes on machined parts.

  6. Clinical applications of Genome Polymorphism Scans

    PubMed Central

    Weber, James L

    2006-01-01

    Applications of Genome Polymorphism Scans range from the relatively simple such as gender determination and confirmation of biological relationships, to the relatively complex such as determination of autozygosity and propagation of genetic information throughout pedigrees. Unlike nearly all other clinical DNA tests, the Scan is a universal test – it covers all people and all genes. In balance, I argue that the Genome Polymorphism Scan is the most powerful, affordable clinical DNA test available today. Reviewers: This article was reviewed by Scott Weiss (nominated by Neil Smalheiser), Roberta Pagon (nominated by Jerzy Jurka) and Val Sheffield (nominated by Neil Smalheiser). PMID:16756678

  7. The false-negative Meckel's scan

    SciTech Connect

    Wilton, G.; Froelich, J.W.

    1982-10-01

    A case is presented of a 17-month-old girl who underwent two Meckel's scans with /sup 99m/Tc pertechnetate. The initial study was interpreted as normal while a subsequent study five days later was definitely positive. Surgery immediately following the positive Meckel's scan demonstrated a Meckel's diverticulum containing gastric mucosa without evidence of active hemorrhage. This prompted a review of the literature in reference to false-negative Meckel's scans which revealed a wide variance in the reported incidence of false-negative examinations. Repeat scintigraphy in the face of a strong clinical suspicion after an initial normal study may decrease the indicence of false-negative imaging series.

  8. Scanning and georeferencing historical USGS quadrangles

    USGS Publications Warehouse

    Davis, Larry R.; Allord, G.J.

    2011-01-01

    The USGS Historical Quadrangle Scanning Project (HQSP) is scanning all scales and all editions of approximately 250,000 topographic maps published by the U.S. Geological Survey (USGS) since the inception of the topographic mapping program in 1884. This scanning will provide a comprehensive digital repository of USGS topographic maps, available to the public at no cost. This project serves the dual purpose of creating a master catalog and digital archive copies of the irreplaceable collection of topographic maps in the USGS Reston Map Library as well as making the maps available for viewing and downloading from the USGS Store and The National Map Viewer.

  9. A microprocessor controlled pressure scanning system

    NASA Technical Reports Server (NTRS)

    Anderson, R. C.

    1976-01-01

    A microprocessor-based controller and data logger for pressure scanning systems is described. The microcomputer positions and manages data from as many as four 48-port electro-mechanical pressure scanners. The maximum scanning rate is 80 pressure measurements per second (20 ports per second on each of four scanners). The system features on-line calibration, position-directed data storage, and once-per-scan display in engineering units of data from a selected port. The system is designed to be interfaced to a facility computer through a shared memory. System hardware and software are described. Factors affecting measurement error in this type of system are also discussed.

  10. Comparison of full-scan and half-scan for cone beam breast CT imaging

    NASA Astrophysics Data System (ADS)

    Chen, Lingyun; Shaw, Chris C.; Lai, Chao-jen; Altunbas, Mustafa C.; Wang, Tianpeng; Tu, Shu-ju; Liu, Xinming

    2006-03-01

    The half-scan cone beam technique, requiring a scan for 180° plus detector width only, can help achieve both shorter scan time as well as higher exposure in each individual projection image. This purpose of this paper is to investigate whether half-scan cone beam CT technique can provide acceptable images for clinical application. The half-scan cone beam reconstruction algorithm uses modified Parker's weighting function and reconstructs from slightly more than half of the projection views for full-scan, giving out promising results. A rotation phantom, stationary gantry bench top system was built to conduct experiments to evaluate half-scan cone beam breast CT technique. A post-mastectomy breast specimen, a stack of lunch meat slices embedded with various sizes of calcifications and a polycarbonate phantom inserted with glandular and adipose tissue equivalents are imaged and reconstructed for comparison study. A subset of full-scan projection images of a mastectomy specimen were extracted and used as the half-scan projection data for reconstruction. The results show half-scan reconstruction algorithm for cone beam breast CT images does not significantly degrade image quality when compared with the images of same or even half the radiation dose level. Our results are encouraging, emphasizing the potential advantages in the use of half-scan technique for cone beam breast imaging.

  11. Laser beam scanning by rotary mirrors. II. Conic-section scan patterns.

    PubMed

    Li, Y

    1995-10-01

    Part II of this study is an application of the general theory of Part I to the following scanners: the galvanometer-based scanner, the paddle scanner, and the regular polygon. The scan field produced by these scanners is (or approximates) a circular cone. Therefore the scan pattern on the plane of observation can be one of the following curves, circle, ellipse, parabola, or hyperbola, depending on the position and orientation of the plane. Special topics to be addressed are (1) the effect of input offset, (2) the locus of the instantaneous scan center and the waist of the scan field, (3) the scanning on curved surfaces, and (4) the generalization of the scan-field expression. In Part III, X-Y scanning will be studied. PMID:21060489

  12. Normative Data for Bone Mass in Healthy Term Infants from Birth to 1 Year of Age

    PubMed Central

    Gallo, Sina; Vanstone, Catherine A.; Weiler, Hope A.

    2012-01-01

    For over 2 decades, dual-energy X-ray absorptiometry (DXA) has been the gold standard for estimating bone mineral density (BMD) and facture risk in adults. More recently DXA has been used to evaluate BMD in pediatrics. However, BMD is usually assessed against reference data for which none currently exists in infancy. A prospective study was conducted to assess bone mass of term infants (37 to 42 weeks of gestation), weight appropriate for gestational age, and born to healthy mothers. The group consisted of 33 boys and 26 girls recruited from the Winnipeg Health Sciences Center (Manitoba, Canada). Whole body (WB) as well as regional sites of the lumbar spine (LS 1–4) and femur was measured using DXA (QDR 4500A, Hologic Inc.) providing bone mineral content (BMC) for all sites and BMD for spine. During the year, WB BMC increased by 200% (76.0 ± 14.2 versus 227.0 ± 29.7 g), spine BMC by 130% (2.35 ± 0.42 versus 5.37 ± 1.02 g), and femur BMC by 190% (2.94 ± 0.54 versus 8.50 ± 1.84 g). Spine BMD increased by 14% (0.266 ± 0.044 versus 0.304 ± 0.044 g/cm2) during the year. This data, representing the accretion of bone mass during the first year of life, is based on a representative sample of infants and will aid in the interpretation of diagnostic DXA scans by researchers and health professionals. PMID:23091773

  13. Prevalent Morphometric Vertebral Fractures in Professional Male Rugby Players

    PubMed Central

    Hind, Karen; Birrell, Fraser; Beck, Belinda

    2014-01-01

    There is an ongoing concern about the risk of injury to the spine in professional rugby players. The objective of this study was to investigate the prevalence of vertebral fracture using vertebral fracture assessment (VFA) dual energy X-ray absorptiometry (DXA) imaging in professional male rugby players. Ninety five professional rugby league (n = 52) and union (n = 43) players (n = 95; age 25.9 (SD 4.3) years; BMI: 29.5 (SD 2.9) kg.m2) participated in the research. Each participant received one VFA, and one total body and lumbar spine DXA scan (GE Lunar iDXA). One hundred and twenty vertebral fractures were identified in over half of the sample by VFA. Seventy four were graded mild (grade 1), 40 moderate (grade 2) and 6 severe (grade 3). Multiple vertebral fractures (≥2) were found in 37 players (39%). There were no differences in prevalence between codes, or between forwards and backs (both 1.2 v 1.4; p>0.05). The most common sites of fracture were T8 (n = 23), T9 (n = 18) and T10 (n = 21). The mean (SD) lumbar spine bone mineral density Z-score was 2.7 (1.3) indicating high player bone mass in comparison with age- and sex-matched norms. We observed a high number of vertebral fractures using DXA VFA in professional rugby players of both codes. The incidence, aetiology and consequences of vertebral fractures in professional rugby players are unclear, and warrant timely, prospective investigation. PMID:24846310

  14. New perspectives in echographic diagnosis of osteoporosis on hip and spine.

    PubMed

    Casciaro, Sergio; Conversano, Francesco; Pisani, Paola; Muratore, Maurizio

    2015-01-01

    Currently, the accepted "gold standard" method for bone mineral density (BMD) measurement and osteoporosis diagnosis is dual-energy X-ray absorptiometry (DXA). However, actual DXA effectiveness is limited by several factors, including intrinsic accuracy uncertainties and possible errors in patient positioning and/or post-acquisition data analysis. DXA employment is also restricted by the typical issues related to ionizing radiation employment (high costs, need of dedicated structures and certified operators, unsuitability for population screenings). The only commercially-available alternative to DXA is represented by "quantitative ultrasound" (QUS) approaches, which are radiation-free, cheaper and portable, but they cannot be applied on the reference anatomical sites (lumbar spine and proximal femur). Therefore, their documented clinical usefulness is restricted to calcaneal applications on elderly patients (aged over 65 y), in combination with clinical risk factors and only for the identification of healthy subjects at low fracture risk. Literature-reported studies performed some QUS measurements on proximal femur, but their clinical translation is mostly hindered by intrinsic factors (e.g., device bulkiness). An innovative ultrasound methodology has been recently introduced, which performs a combined analysis of B-mode images and corresponding "raw" radiofrequency signals acquired during an echographic scan of the target reference anatomical site, providing two novel parameters: Osteoporosis Score and Fragility Score, indicative of BMD level and bone strength, respectively. This article will provide a brief review of the available systems for osteoporosis diagnosis in clinical routine contexts, followed by a synthesis of the most promising research results on the latest ultrasound developments for early osteoporosis diagnosis and fracture prevention. PMID:26604940

  15. Use of Strontium Chloride for the Treatment of Osteoporosis: A Case Report.

    PubMed

    Westberg, Sarah M; Awker, Amy; Torkelson, Carolyn J

    2016-03-01

    Context • Strontium ranelate is an approved prescription medication for the treatment of osteoporosis in Europe. In the United States, the only available forms of strontium are those that are nonprescription, dietary supplements. Some patients with osteoporosis use those products because they prefer an alternate treatment to conventional therapy. Currently, no controlled trials have been conducted on the effectiveness of the supplements for treating osteoporosis. Objective • The study intended to examine how one woman responded to the use of strontium chloride. Design • This was a retrospective case study. Setting • The woman in the case study was a patient in an academic urban women's health clinic in Minneapolis, MN, USA. Participant • The participant was a postmenopausal woman with a history of vertebral fracture. Intervention • The participant took 680 mg daily of strontium chloride for 2.5 y. Outcome Measures • The patient had begun receiving dual-energy X-ray absorptiometry (DXA) scans in 2004 and continued to receive follow-up scans every 2 y. After beginning strontium therapy in December 2011, she received DXA scans in March 2012 and May 2014. Results • During the study, the analysis of the patient's DXA scans showed a positive increase in the bone mineral density (BMD) of her vertebrae and her right hip and maintenance of her BMD in her left hip. Conclusions • Although the current case report does not provide enough evidence to conclude that US dietary supplements of strontium are effective in preventing fractures, it demonstrates a positive experience for one patient. PMID:27228273

  16. Indium-111 leukocyte scanning and fracture healing

    SciTech Connect

    Mead, L.P.; Scott, A.C.; Bondurant, F.J.; Browner, B.D. )

    1990-01-01

    This study was undertaken to determine the specificity of indium-111 leukocyte scans for osteomyelitis when fractures are present. Midshaft tibial osteotomies were performed in 14 New Zealand white rabbits, seven of which were infected postoperatively with Staphylococcus aureus per Norden's protocol. All 14 rabbits were scanned following injection with 75 microCi of indium 111 at 72 h after osteotomy and at weekly intervals for 4 weeks. Before the rabbits were killed, the fracture sites were cultured to document the presence or absence of infection. The results of all infected osteotomy sites were positive, whereas no positive scans were found in the noninfected osteotomies. We concluded from this study that uncomplicated fracture healing does not result in a positive indium-111 leukocyte scan.

  17. The design of laser scanning galvanometer system

    NASA Astrophysics Data System (ADS)

    Sun, Xiaoling; Zhou, Bin; Xie, Weihao; Zhang, Yuangeng

    2015-02-01

    In this paper, we designed the laser scanning galvanometer system according to our requirements. Based on scanning range of our laser scanning galvanometer system, the design parameters of this system were optimized. During this work, we focused on the design of the f-θ field lens. An optical system of patent lens in the optical manual book, which had three glasses structure, was used in our designs. Combining the aberration theory, the aberration corrections and image quality evaluations were finished using Code V optical design software. An optimum f-θ field lens was designed, which had focal length of 434 mm, pupil diameter of 30 mm, scanning range of 160 mm × 160 mm, and half field angle of 18°×18°. At the last, we studied the influences of temperature changes on our system.

  18. Nanoscale thermometry by scanning thermal microscopy

    NASA Astrophysics Data System (ADS)

    Menges, Fabian; Riel, Heike; Stemmer, Andreas; Gotsmann, Bernd

    2016-07-01

    Measuring temperature is a central challenge in nanoscience and technology. Addressing this challenge, we report the development of a high-vacuum scanning thermal microscope and a method for non-equilibrium scanning probe thermometry. The microscope is built inside an electromagnetically shielded, temperature-stabilized laboratory and features nanoscopic spatial resolution at sub-nanoWatt heat flux sensitivity. The method is a dual signal-sensing technique inferring temperature by probing a total steady-state heat flux simultaneously to a temporally modulated heat flux signal between a self-heated scanning probe sensor and a sample. Contact-related artifacts, which so far limit the reliability of nanoscopic temperature measurements by scanning thermal microscopy, are minimized. We characterize the microscope's performance and demonstrate the benefits of the new thermometry approach by studying hot spots near lithographically defined constrictions in a self-heated metal interconnect.

  19. SCAN secure processor and its biometric capabilities

    NASA Astrophysics Data System (ADS)

    Kannavara, Raghudeep; Mertoguno, Sukarno; Bourbakis, Nikolaos

    2011-04-01

    This paper presents the design of the SCAN secure processor and its extended instruction set to enable secure biometric authentication. The SCAN secure processor is a modified SparcV8 processor architecture with a new instruction set to handle voice, iris, and fingerprint-based biometric authentication. The algorithms for processing biometric data are based on the local global graph methodology. The biometric modules are synthesized in reconfigurable logic and the results of the field-programmable gate array (FPGA) synthesis are presented. We propose to implement the above-mentioned modules in an off-chip FPGA co-processor. Further, the SCAN-secure processor will offer a SCAN-based encryption and decryption of 32 bit instructions and data.

  20. Noncontact dimensional measurement system using holographic scanning

    NASA Astrophysics Data System (ADS)

    Sagan, Stephen F.; Rosso, Robert S.; Rowe, David M.

    1997-07-01

    Holographic scanning systems have been used for years in point-of-sale bar code scanners and other low resolution applications. These simple scanning systems could not successfully provide the accuracy and precision required to measure, inspect and control the production of today's high tech optical fibers, medical extrusions and electrical cables. A new class of instruments for the precision measurement of industrial processes has been created by the development of systems with a unique combination of holographic optical elements that can compensate for the wavelength drift in laser diodes, the application of proprietary post-processing algorithms, and the advancements in replication methods to fabricate low cost holographic scanning discs. These systems have improved upon the performance of traditional polygon mirror scanners. This paper presents the optical configuration and design features that have been incorporated into a holographic scanning inspection system that provides higher productivity, increased product quality and lower production costs for many manufacturers.

  1. Diagnosis of thyroid disease on bone scans

    SciTech Connect

    Peterdy, A.E.

    1985-03-01

    Three cases are reported in which visualization of the thyroid occurred during Tc-99m pyrophosphate bone scans. All were found to be hyperthyroid with elevated serum thyroid hormone and two patients also had elevated 4-hour radioactive iodine uptakes.

  2. Electron Beam Scanning in Industrial Applications

    NASA Astrophysics Data System (ADS)

    Jongen, Yves; Herer, Arnold

    1996-05-01

    Scanned electron beams are used within many industries for applications such as sterilization of medical disposables, crosslinking of wire and cables insulating jackets, polymerization and degradation of resins and biomaterials, modification of semiconductors, coloration of gemstones and glasses, removal of oxides from coal plant flue gasses, and the curing of advanced composites and other molded forms. X-rays generated from scanned electron beams make yet other applications, such as food irradiation, viable. Typical accelerators for these applications range in beam energy from 0.5MeV to 10 MeV, with beam powers between 5 to 500kW and scanning widths between 20 and 300 cm. Since precise control of dose delivery is required in many of these applications, the integration of beam characteristics, product conveyance, and beam scanning mechanisms must be well understood and optimized. Fundamental issues and some case examples are presented.

  3. Intelligent Classification and Visualization of Network Scans

    SciTech Connect

    Chen, L; Muelder, C; Ma, K; Bartoletti, A

    2007-03-01

    Network scans are a common first step in a network intrusion attempt. In order to gain information about a potential network intrusion, it is beneficial to analyze these network scans. Statistical methods such as wavelet scalogram analysis have been used along with visualization techniques in previous methods. However, applying these statistical methods to reduce the data causes a substantial amount of data loss. This paper presents a study of using associative memory learning techniques to directly compare network scans in order to create a classification which can be used by itself or in conjunction with existing visualization techniques to better characterize the sources of these scans. This produces an integrated system of visual and intelligent analysis which is applicable to real world data.

  4. Scanning tunneling microscopy imaging of nanotubes

    SciTech Connect

    Antonenko, S. V. Malinovskaya, O. S.; Mal'tsev, S. N.

    2007-07-15

    Samples of carbon paper containing multiwalled carbon nanotube films are produced by current annealing. A scanning tunneling microscope is used to examine the structure of the modified carbon paper. X-, Y-, and V-shaped nanotubes are found.

  5. Nanoscale thermometry by scanning thermal microscopy.

    PubMed

    Menges, Fabian; Riel, Heike; Stemmer, Andreas; Gotsmann, Bernd

    2016-07-01

    Measuring temperature is a central challenge in nanoscience and technology. Addressing this challenge, we report the development of a high-vacuum scanning thermal microscope and a method for non-equilibrium scanning probe thermometry. The microscope is built inside an electromagnetically shielded, temperature-stabilized laboratory and features nanoscopic spatial resolution at sub-nanoWatt heat flux sensitivity. The method is a dual signal-sensing technique inferring temperature by probing a total steady-state heat flux simultaneously to a temporally modulated heat flux signal between a self-heated scanning probe sensor and a sample. Contact-related artifacts, which so far limit the reliability of nanoscopic temperature measurements by scanning thermal microscopy, are minimized. We characterize the microscope's performance and demonstrate the benefits of the new thermometry approach by studying hot spots near lithographically defined constrictions in a self-heated metal interconnect. PMID:27475585

  6. Breadboard linear array scan imager program

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The performance was evaluated of large scale integration photodiode arrays in a linear array scan imaging system breadboard for application to multispectral remote sensing of the earth's resources. Objectives, approach, implementation, and test results of the program are presented.

  7. Scanning probe microscopy on new dental alloys

    NASA Astrophysics Data System (ADS)

    Reusch, B.; Geis-Gerstorfer, J.; Ziegler, C.

    Surface analytical methods such as scanning force microscopy (SFM), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were used to determine the surface properties of amalgam substitutes as tooth filling materials. In particular the corrosion and the passivation behavior of new gallium restorative materials were studied. To give relevant practical data, the measurements were performed with and without the alloys being stored in artificial saliva to simulate physiological oral conditions.

  8. Scanning fluorescent microthermal imaging apparatus and method

    DOEpatents

    Barton, D.L.; Tangyunyong, P.

    1998-01-06

    A scanning fluorescent microthermal imaging (FMI) apparatus and method is disclosed, useful for integrated circuit (IC) failure analysis, that uses a scanned and focused beam from a laser to excite a thin fluorescent film disposed over the surface of the IC. By collecting fluorescent radiation from the film, and performing point-by-point data collection with a single-point photodetector, a thermal map of the IC is formed to measure any localized heating associated with defects in the IC. 1 fig.

  9. Holographic Optical Elements as Scanning Lidar Telescopes

    NASA Technical Reports Server (NTRS)

    Schwemmer, Geary K.; Rallison, Richard D.; Wilkerson, Thomas D.; Guerra, David V.

    2003-01-01

    We have investigated and developed the use of holographic optical elements (HOE) and holographic transmission gratings for scanning lidar telescopes. By rotating a flat HOE in its own plane with the focal spot on the rotation axis, a very simple and compact conical scanning telescope is possible. We developed and tested transmission and reflection HOES for use with the first three harmonics of Nd:YAG lasers, and designed, built, and tested two lidar systems based on this technology.

  10. Scanning fluorescent microthermal imaging apparatus and method

    DOEpatents

    Barton, Daniel L.; Tangyunyong, Paiboon

    1998-01-01

    A scanning fluorescent microthermal imaging (FMI) apparatus and method is disclosed, useful for integrated circuit (IC) failure analysis, that uses a scanned and focused beam from a laser to excite a thin fluorescent film disposed over the surface of the IC. By collecting fluorescent radiation from the film, and performing point-by-point data collection with a single-point photodetector, a thermal map of the IC is formed to measure any localized heating associated with defects in the IC.

  11. CT Scans - Multiple Languages: MedlinePlus

    MedlinePlus

    ... الأشعة المقطعية الحاسوبية - العربية Bilingual PDF Health Information Translations Chinese - Simplified (简体中文) CT (Computerized Tomography) Scan CT ( ... 扫描 - 简体中文 (Chinese - Simplified) Bilingual PDF Health Information Translations Chinese - Traditional (繁體中文) CT (Computerized Tomography) Scan CT ( ...

  12. Feature Adaptive Sampling for Scanning Electron Microscopy

    PubMed Central

    Dahmen, Tim; Engstler, Michael; Pauly, Christoph; Trampert, Patrick; de Jonge, Niels; Mücklich, Frank; Slusallek, Philipp

    2016-01-01

    A new method for the image acquisition in scanning electron microscopy (SEM) was introduced. The method used adaptively increased pixel-dwell times to improve the signal-to-noise ratio (SNR) in areas of high detail. In areas of low detail, the electron dose was reduced on a per pixel basis, and a-posteriori image processing techniques were applied to remove the resulting noise. The technique was realized by scanning the sample twice. The first, quick scan used small pixel-dwell times to generate a first, noisy image using a low electron dose. This image was analyzed automatically, and a software algorithm generated a sparse pattern of regions of the image that require additional sampling. A second scan generated a sparse image of only these regions, but using a highly increased electron dose. By applying a selective low-pass filter and combining both datasets, a single image was generated. The resulting image exhibited a factor of ≈3 better SNR than an image acquired with uniform sampling on a Cartesian grid and the same total acquisition time. This result implies that the required electron dose (or acquisition time) for the adaptive scanning method is a factor of ten lower than for uniform scanning. PMID:27150131

  13. Radionuclide bone scanning of medullary chondrosarcoma

    SciTech Connect

    Hudson, T.M.; Chew, F.S.; Manaster, B.J.

    1982-12-01

    /sup 99m/Tc methylene diphosphonate bone scans of 18 medullary chondrosarcomas of bone were correlated with pathologic macrosections of the resected tumors. There was increased scan uptake by all 18 tumors, and the uptake in 15 scans corresponded accurately to the anatomic extent of the tumors. Only three scans displayed increased uptake beyond the true tumor margins; thus, the extended pattern of uptake beyond the true tumor extent is much less common in medullary chondrosarcomas than in many other primary bone tumors. Therefore, increased uptake beyond the apparent radiographic margin of the tumor suggests possible occult tumor spread. Pathologically, there was intense reactive new bone formation and hyperemia around the periphery of all 18 tumors, and there were foci of enchondral ossification, hyperemia, or calcification within the tumor itself in nearly every tumor. Three scans displayed less uptake in the center of the tumors than around their peripheries. One of these tumors was necrotic in the center, but the other two were pathologically no different from tumors that displayed homogeneous uptake on the scan.

  14. Scan path entropy and arrow plots: capturing scanning behavior of multiple observers.

    PubMed

    Hooge, Ignace; Camps, Guido

    2013-01-01

    Designers of visual communication material want their material to attract and retain attention. In marketing research, heat maps, dwell time, and time to AOI first hit are often used as evaluation parameters. Here we present two additional measures (1) "scan path entropy" to quantify gaze guidance and (2) the "arrow plot" to visualize the average scan path. Both are based on string representations of scan paths. The latter also incorporates transition matrices and time required for 50% of the observers to first hit AOIs (T50). The new measures were tested in an eye tracking study (48 observers, 39 advertisements). Scan path entropy is a sensible measure for gaze guidance and the new visualization method reveals aspects of the average scan path and gives a better indication in what order global scanning takes place. PMID:24399993

  15. Special raster scanning for reduction of charging effects in scanning electron microscopy.

    PubMed

    Suzuki, Kazuhiko; Oho, Eisaku

    2014-01-01

    A special raster scanning (SRS) method for reduction of charging effects is developed for the field of SEM. Both a conventional fast scan (horizontal direction) and an unusual scan (vertical direction) are adopted for acquiring raw data consisting of many sub-images. These data are converted to a proper SEM image using digital image processing techniques. About sharpness of the image and reduction of charging effects, the SRS is compared with the conventional fast scan (with frame-averaging) and the conventional slow scan. Experimental results show the effectiveness of SRS images. By a successful combination of the proposed scanning method and low accelerating voltage (LV)-SEMs, it is expected that higher-quality SEM images can be more easily acquired by the considerable reduction of charging effects, while maintaining the resolution.

  16. Scan path entropy and arrow plots: capturing scanning behavior of multiple observers

    PubMed Central

    Hooge, Ignace; Camps, Guido

    2013-01-01

    Designers of visual communication material want their material to attract and retain attention. In marketing research, heat maps, dwell time, and time to AOI first hit are often used as evaluation parameters. Here we present two additional measures (1) “scan path entropy” to quantify gaze guidance and (2) the “arrow plot” to visualize the average scan path. Both are based on string representations of scan paths. The latter also incorporates transition matrices and time required for 50% of the observers to first hit AOIs (T50). The new measures were tested in an eye tracking study (48 observers, 39 advertisements). Scan path entropy is a sensible measure for gaze guidance and the new visualization method reveals aspects of the average scan path and gives a better indication in what order global scanning takes place. PMID:24399993

  17. Effects of scanning orientation on outlier formation in 3D laser scanning of reflective surfaces

    NASA Astrophysics Data System (ADS)

    Wang, Yutao; Feng, Hsi-Yung

    2016-06-01

    Inspecting objects with reflective surfaces using 3D laser scanning is a demanded but challenging part inspection task due to undesirable specular reflections, which produce extensive outliers in the scanned point cloud. These outliers need to be removed in order to alleviate subsequent data processing issues. Many existing automatic outlier removal methods do not detect outliers according to the outlier formation properties. As a result, these methods only offer limited capabilities in removing extensive and complex outliers from scanning objects with reflective surfaces. This paper reports an empirical study which experimentally investigates the outlier formation characteristics in relation to the scanning orientation of the laser probe. The objective is to characterize the scanning orientation effects on outlier formation in order to facilitate the development of an effective outlier detection and removal method. Such an experimental investigation was hardly done before. It has been found in this work that scanning orientation can directly affect outlier extensity and occurrence in 3D laser scanning. A general guidance on proper scan path planning can then be provided with an aim to reduce the occurrence of outliers. Further, the observed dependency of outlier formation on scanning orientation can be exploited to facilitate effective and automatic outlier detection and removal.

  18. CT Scan of NASA Booster Nozzle

    SciTech Connect

    Schneberk, D; Perry, R; Thompson, R

    2004-07-27

    We scanned a Booster Nozzle for NASA with our 9 meV LINAC, AmSi panel scanner. Three scans were performed using different filtering schemes and different positions of the nozzle. The results of the scan presented here are taken from the scan which provided the best contrast and lowest noise of the three. Our inspection data shows a number of indications of voids in the outer coating of rubber/carbon. The voids are mostly on the side of the nozzle, but a few small voids are present at the ends of the nozzle. We saw no large voids in the adhesive layer between the Aluminum and the inner layer of carbon. This 3D inspection data did show some variation in the size of the adhesive layer, but none of the indications were larger than 3 pixels in extent (21 mils). We have developed a variety of contour estimation and extraction techniques for inspecting small spaces between layers. These tools might work directly on un-sectioned nozzles since the circular contours will fit with our tools a little better. Consequently, it would be useful to scan a full nozzle to ensure there are no untoward degradations in data quality, and to see if our tools would work to extract the adhesive layer.

  19. Simple Cassegrain scanning system for infrared astronomy

    NASA Technical Reports Server (NTRS)

    Apt, J.; Goody, R.; Mertz, L.

    1980-01-01

    To meet the need for a reliable, fast imaging system capable of being taken rapidly on and off the telescope, a simple, inexpensive, and compact Cassegrain reimaging system for scanning IR images was constructed. Using commercially available components without requiring close mechanical tolerances, the design solves the problem of beam stability pointed out by Koornneef and van Overbeeke (1976). For the moving-iron galvanometer scanner, it is noted that at the imaging frequency of 0.5 Hz, hysteresis in image plane motion was found to be less than 0.2 arc sec for a 64-arc sec scan, and the deviation from linearity with a triangular wave input was found to be less than 0.3 arc sec. This system and a scanning secondary were used to image Venus at 11.5 microns, and compared with the scanning secondary, the reimaging system did not appear to contribute any additional noise, considerably improved mechanical reliability, and eliminated cross-scan motion

  20. Scanning-time evaluation of Digimarc Barcode

    NASA Astrophysics Data System (ADS)

    Gerlach, Rebecca; Pinard, Dan; Weaver, Matt; Alattar, Adnan

    2015-03-01

    This paper presents a speed comparison between the use of Digimarc® Barcodes and the Universal Product Code (UPC) for customer checkout at point of sale (POS). The recently introduced Digimarc Barcode promises to increase the speed of scanning packaged goods at POS. When this increase is exploited by workforce optimization systems, the retail industry could potentially save billions of dollars. The Digimarc Barcode is based on Digimarc's watermarking technology, and it is imperceptible, very robust, and does not require any special ink, material, or printing processes. Using an image-based scanner, a checker can quickly scan consumer packaged goods (CPG) embedded with the Digimarc Barcode without the need to reorient the packages with respect to the scanner. Faster scanning of packages saves money and enhances customer satisfaction. It reduces the length of the queues at checkout, reduces the cost of cashier labor, and makes self-checkout more convenient. This paper quantifies the increase in POS scanning rates resulting from the use of the Digimarc Barcode versus the traditional UPC. It explains the testing methodology, describes the experimental setup, and analyzes the obtained results. It concludes that the Digimarc Barcode increases number of items per minute (IPM) scanned at least 50% over traditional UPC.

  1. Optical scanning system for laser velocimeter

    NASA Technical Reports Server (NTRS)

    Rhodes, D. B.

    1977-01-01

    An optical system was developed to provide fast incremental scanning of a backscattered laser velocimeter focus point over a 36-cm distance. The system is used to measure flow velocities at 16 positions along its optical axis and to scan these 16 positions up to 30 times a second. Dwell time at each location is approximately 2 milliseconds. Sample volumes typically are 0.2 mm in diameter by 1.4 cm in length. The optical scanning system consists of a wheel containing plane parallel quartz windows of various thicknesses. The laser velocimeter beams are imaged to a primary focus within the dead airspace of an optical cell. The beams emerging from the cell pass through the windows of the scanning wheel. The refraction of the beams passing through the windows causes an apparent shift of the focus within the optical cell and hence in the test zone. Light scattered from the secondary focus within the test zone is concurrently collected and reimaged through the same optical path which originally projected the primary focus. The reimaged backscattered light containing the velocity information is then collected and focused onto a photomultiplier detector system to complete the scanned laser velocimeter optical system.

  2. GT-Scan: identifying unique genomic targets

    PubMed Central

    O’Brien, Aidan; Bailey, Timothy L.

    2014-01-01

    Summary: A number of technologies, including CRISPR/Cas, transcription activator-like effector nucleases and zinc-finger nucleases, allow the user to target a chosen locus for genome editing or regulatory interference. Specificity, however, is a major problem, and the targeted locus must be chosen with care to avoid inadvertently affecting other loci (‘off-targets’) in the genome. To address this we have created ‘Genome Target Scan’ (GT-Scan), a flexible web-based tool that ranks all potential targets in a user-selected region of a genome in terms of how many off-targets they have. GT-Scan gives the user flexibility to define the desired characteristics of targets and off-targets via a simple ‘target rule’, and its interactive output allows detailed inspection of each of the most promising candidate targets. GT-Scan can be used to identify optimal targets for CRISPR/Cas systems, but its flexibility gives it potential to be adapted to other genome-targeting technologies as well. Availability and implementation: GT-Scan can be run via the web at: http://gt-scan.braembl.org.au. Contact: t.bailey@uq.edu.au PMID:24860161

  3. About infrared scanning of photovoltaic solar plant

    NASA Astrophysics Data System (ADS)

    Kauppinen, T.; Panouillot, P.-E.; Siikanen, S.; Athanasakou, E.; Baltas, P.; Nikopoulous, B.

    2015-05-01

    The paper is discussing about infrared scanning of PV solar plants. It is important that the performance of each solar panel and cell is verified. One new possibility compared to traditional ground-based scanning (handheld camera) is the utilization of UAV (Unmanned Aerial Vehicle). In this paper results from a PV solar Plant in Western Greece are introduced. The nominal power of the solar plants were 0, 9 MW and 2 MW and they were scanned both by a ground-controlled drone and by handheld equipment. It is essential to know all the factors effecting to results and also the time of scanning is important. The results done from the drone and from ground-based scanning are compared; also results from various altitudes and time of day are discussed. The UAV (Unmanned Aerial Vehicle/RPAS (Remote Piloted Aircraft Systems) will give an excellent opportunity to monitor various targets which are impossible or difficult to access from the ground. Compared to fixed-wing and helicopter-based platforms it will give advantages but also this technology has limitations. One limitation is the weight of the equipment and the short operational range and short flight time. Also valid procedures must be created for different solutions in the future. The most important thing, as in all infrared thermography applications, is the proper interpretation of results.

  4. Association between Bone Mass and Dental Hypomineralization.

    PubMed

    van der Tas, J T; Elfrink, M E C; Vucic, S; Heppe, D H M; Veerkamp, J S J; Jaddoe, V W V; Rivadeneira, F; Hofman, A; Moll, H A; Wolvius, E B

    2016-04-01

    The aim of this study was to examine the association between the bone mass (bone mineral content [BMC]) and hypomineralized second primary molars (HSPMs)/molar incisor hypomineralization (MIH) in 6-y-old children. This cross-sectional study was embedded in the Generation R Study, a population-based prospective cohort study, starting from fetal life until adulthood in Rotterdam, Netherlands. The European Academy of Pediatric Dentistry criteria were used to score the intraoral photographs on the presence or absence of HSPMs and MIH. Bone mass was measured with a dual-energy x-ray absorptiometry (DXA) scan. Intraoral photographs and DXA scans were available in 6,510 6-y-old children. Binary logistic regression models were used to study the association between the bone mass and HSPMs/MIH. In total, 5,586 children had their second primary molars assessed and a DXA scan made; 507 children were diagnosed with HSPM. Of 2,370 children with data on their permanent first molars, 203 were diagnosed with MIH. In the fully adjusted model, children with lower BMC (corrected for bone area) were more likely to have HSPMs (odds ratio, 1.13; 95% confidence interval, 1.02 to 1.26 per 1-standard deviation decrease). A lower BMC (corrected for bone area) was not associated with MIH (odds ratio, 1.02; 95% confidence interval, 0.87 to 1.20 per 1-standard deviation decrease). We observed a negative association between BMC (corrected for bone area) and HSPMs. No association was found between BMC (corrected for bone area) and MIH. Future research should focus on investigating the mechanism underlying the negative association between the bone mass and HSPMs. Our study, in a large population of 6-y-old children, adds the finding that BMC (corrected for bone size) is associated with HSPMs but not with MIH in childhood. PMID:26747420

  5. Quantification of pilot workload via instrument scan

    NASA Technical Reports Server (NTRS)

    Tole, J. R.; Stephens, A. T.; Harris, R. L., Sr.; Ephrath, A.

    1982-01-01

    The use of visual scanning behavior as an indicator of pilot workload is described. The relationship between level of performance on a constant piloting task under simulated IFR conditions, the skill of the pilot the level of mental workload induced by an additional verbal task imposed on the basic control task, and visual scanning behavior is investigated. An increase in fixation dwell times, especially on the primary instrument with increased mental loading is indicated. Skilled subjects 'stared' less under increased loading than did novice pilots. Sequences of instrument fixations were also examined. The percentage occurrence of the subject's most used sequences decreased with increased task difficulty for novice subjects but not for highly skilled subjects. Entropy rate (bits/sec) of the sequence of fixations was also used to quantify the scan pattern. It consistently decreased for most subjects as the four loading levels used increased.

  6. Visual scanning behavior and pilot workload

    NASA Technical Reports Server (NTRS)

    Harris, R. L., Sr.; Tole, J. R.; Stephens, A. T.; Ephrath, A. R.

    1982-01-01

    This paper describes an experimental paradigm and a set of results which demonstrate a relationship between the level of performance on a skilled man-machine control task, the skill of the operator, the level of mental difficulty induced by an additional task imposed on the basic control task, and visual scanning performance. During a constant, simulated piloting task, visual scanning of instruments was found to vary with the difficulty of a verbal mental loading task. The average dwell time of each fixation on the pilot's primary instrument increased with the estimated skill level of the pilots, with novices being affected by the loading task much more than experts. The results suggest that visual scanning of instruments in a controlled task may be an indicator of both workload and skill.

  7. Conductivity map from scanning tunneling potentiometry

    NASA Astrophysics Data System (ADS)

    Zhang, Hao; Li, Xianqi; Chen, Yunmei; Durand, Corentin; Li, An-Ping; Zhang, X.-G.

    2016-08-01

    We present a novel method for extracting two-dimensional (2D) conductivity profiles from large electrochemical potential datasets acquired by scanning tunneling potentiometry of a 2D conductor. The method consists of a data preprocessing procedure to reduce/eliminate noise and a numerical conductivity reconstruction. The preprocessing procedure employs an inverse consistent image registration method to align the forward and backward scans of the same line for each image line followed by a total variation (TV) based image restoration method to obtain a (nearly) noise-free potential from the aligned scans. The preprocessed potential is then used for numerical conductivity reconstruction, based on a TV model solved by accelerated alternating direction method of multiplier. The method is demonstrated on a measurement of the grain boundary of a monolayer graphene, yielding a nearly 10:1 ratio for the grain boundary resistivity over bulk resistivity.

  8. Dynamic CT scanning of spinal column trauma

    SciTech Connect

    Brown, B.M.; Brant-Zawadzki, M.; Cann, C.E.

    1982-12-01

    Dynamic sequential computed tomographic scanning with automatic table incrementation uses low milliampere-second technique to eliminate tube cooling delays between scanning slices and, thus, markedly shortens examination times. A total of 25 patients with spinal column trauma involving 28 levels were studied with dynamic scans and retrospectively reviewed. Dynamic studies were considerably faster than conventional spine examinations and yielded reliable diagnosis. Bone disruption and subluxation was accurately evaluated, and the use of intrathecal metrizamide in low doses allowed direct visualization of spinal cord or radicular compromise. Multiplanar image reformation was aided by the dynamic incrementation technique, since motion between slices (and the resulting misregistration artifact on image reformation) was minimized. A phantom was devised to test spatial resolution of computed tomography for objects 1-3 mm in size and disclosed minimal differences for dynamic and conventional computed tomographic techniques in resolving medium-to-high-contrast objects.

  9. Human performance in radiological survey scanning

    SciTech Connect

    Brown, W.S.; Abelquist, E.W.

    1998-03-01

    The probability of detecting residual contamination in the field using portable radiological survey instruments depends not only on the sensitivity of the instrumentation used in scanning, but also on the surveyor`s performance. This report provides a basis for taking human performance into account in determining the minimum level of activity detectable by scanning. A theoretical framework was developed (based on signal detection theory) which allows influences on surveyors to be anticipated and understood, and supports a quantitative assessment of performance. The performance of surveyors under controlled yet realistic field conditions was examined to gain insight into the task and to develop means of quantifying performance. Then, their performance was assessed under laboratory conditions to quantify more precisely their ability to make the required discriminations. The information was used to characterize surveyors` performance in the scanning task and to provide a basis for predicting levels of radioactivity that are likely to be detectable under various conditions by surveyors using portable survey instruments.

  10. Conductivity map from scanning tunneling potentiometry.

    PubMed

    Zhang, Hao; Li, Xianqi; Chen, Yunmei; Durand, Corentin; Li, An-Ping; Zhang, X-G

    2016-08-01

    We present a novel method for extracting two-dimensional (2D) conductivity profiles from large electrochemical potential datasets acquired by scanning tunneling potentiometry of a 2D conductor. The method consists of a data preprocessing procedure to reduce/eliminate noise and a numerical conductivity reconstruction. The preprocessing procedure employs an inverse consistent image registration method to align the forward and backward scans of the same line for each image line followed by a total variation (TV) based image restoration method to obtain a (nearly) noise-free potential from the aligned scans. The preprocessed potential is then used for numerical conductivity reconstruction, based on a TV model solved by accelerated alternating direction method of multiplier. The method is demonstrated on a measurement of the grain boundary of a monolayer graphene, yielding a nearly 10:1 ratio for the grain boundary resistivity over bulk resistivity.

  11. RADSCAN - A novel conically scanning tracking feed

    NASA Astrophysics Data System (ADS)

    Sullivan, A.

    The SCR-584 radar, which was developed as one of the first tracking systems at the beginning of 1942, used a conically scanning technique. A unique conically scanned feed, called RADSCAN, which has but one moving part and no rotary joint, has now been developed by an American company. A pair of stationary orthogonal printed circuit dipoles are used to excite the TE11 mode in the rotating circular waveguide. The displacement of the phase center of the circular waveguide from the boresight axis causes the conical scanning. The single-channel monopulse technique is discussed, and a comparison of RADSCAN and the single channel monopulse is conducted. Attention is given to aspects of reliability, low-angle tracking, beam crossover variation with frequency, cross talk, error modulation, and boresight shift with frequency.

  12. Conductivity map from scanning tunneling potentiometry.

    PubMed

    Zhang, Hao; Li, Xianqi; Chen, Yunmei; Durand, Corentin; Li, An-Ping; Zhang, X-G

    2016-08-01

    We present a novel method for extracting two-dimensional (2D) conductivity profiles from large electrochemical potential datasets acquired by scanning tunneling potentiometry of a 2D conductor. The method consists of a data preprocessing procedure to reduce/eliminate noise and a numerical conductivity reconstruction. The preprocessing procedure employs an inverse consistent image registration method to align the forward and backward scans of the same line for each image line followed by a total variation (TV) based image restoration method to obtain a (nearly) noise-free potential from the aligned scans. The preprocessed potential is then used for numerical conductivity reconstruction, based on a TV model solved by accelerated alternating direction method of multiplier. The method is demonstrated on a measurement of the grain boundary of a monolayer graphene, yielding a nearly 10:1 ratio for the grain boundary resistivity over bulk resistivity. PMID:27587126

  13. A radiographic scanning technique for cores

    USGS Publications Warehouse

    Hill, G.W.; Dorsey, M.E.; Woods, J.C.; Miller, R.J.

    1979-01-01

    A radiographic scanning technique (RST) can produce single continuous radiographs of cores or core sections up to 1.5 m long and up to 30 cm wide. Changing a portable industrial X-ray unit from the normal still-shot mode to a scanning mode requires simple, inexpensive, easily constructed, and highly durable equipment. Additional components include a conveyor system, antiscatter cylinder-diaphragm, adjustable sample platform, developing tanks, and a contact printer. Complete cores, half cores, sample slabs or peels may be scanned. Converting the X-ray unit from one mode to another is easy and can be accomplished without the use of special tools. RST provides the investigator with a convenient, continuous, high quality radiograph, saves time and money, and decreases the number of times cores have to be handled. ?? 1979.

  14. Visual scanning behavior and pilot workload

    NASA Technical Reports Server (NTRS)

    Harris, R. L., Sr.; Tole, J. R.; Stephens, A. T.; Ephrath, A. R.

    1981-01-01

    An experimental paradigm and a set of results which demonstrate a relationship between the level of performance on a skilled man-machine control task, the skill of the operator, the level of mental difficulty induced by an additional task imposed on the basic control task, and visual scanning performance. During a constant, simulated piloting task, visual scanning of instruments was found to vary as a function of the level of difficulty of a verbal mental loading task. The average dwell time of each fixation on the pilot's primary instrument increased as a function of the estimated skill level of the pilots, with novices being affected by the loading task much more than the experts. The results suggest that visual scanning of instruments in a controlled task may be an indicator of both workload and skill.

  15. Scanning microfluorometry in intravital microvascular research.

    PubMed

    Witte, S

    1989-01-01

    Our own development of fluorometric scanning techniques in intravital microscopy of the microcirculation is described. Very tiny amount of fluorometric substances are detected with a high temporal and locational resolution. The everted small intestinal mesentery of the rat serves as a model. We have given a detailed description of the microscopes used, the optical systems, the conditions of measurement of the microfluorometry, the scanning techniques and the evaluation of the measurement data. The present state of technical development detects 10(-12) g of a fluorochromed plasma protein in 8 ms in a measurement field of 2 microns 2. The four-digit measurement data of a scanning line of 200 microns length in 0.25 micron locational resolution are registered in about 2 s.

  16. Lateral scanning white-light interferometer.

    PubMed

    Olszak, A

    2000-08-01

    White-light vertical scanning interferometry is a well-established technique for retrieving the three-dimensional shapes of small objects, but it can measure only areas as big as the field of view of the instrument. For bigger fields a stitching algorithm must be applied, which often can be a source of errors. A technique in which the object is scanned laterally in front of an instrument with a tilted coherence plane is described. It permits measurements at higher speeds while measurement accuracy is retained and eliminates the need for stitching in one direction. Experimental confirmation is provided.

  17. Optically Detected Scanned Probe Magnetic Resonance Imaging

    NASA Astrophysics Data System (ADS)

    Wolfe, Christopher; Bhallamudi, Vidya; Wang, Hailong; Du, Chunhui; Manuilov, Sergei; Adur, Rohan; Yang, Fengyuan; Hammel, P. Chris

    2014-03-01

    Magnetic resonance is a powerful tool for studying magnetic properties and dynamics of spin systems. Scanned magnetic probes can induce spatially localized resonance due to the strong magnetic field and gradient near the magnetic tip., Nitrogen vacancy centers (NV) in diamond provide a sensitive means of measuring magnetic fields at the nanoscale. We report preliminary results towards using the high sensitivity of NV detection with a scanned magnetic probe to study local magnetic phenomena. This work is supported by the Center for Emergent Materials at The Ohio State University, a NSF Materials Research Science and Engineering Center (DMR-0820414).

  18. Scanning and storage of electrophoretic records

    DOEpatents

    McKean, Ronald A.; Stiegman, Jeff

    1990-01-01

    An electrophoretic record that includes at least one gel separation is mounted for motion laterally of the separation record. A light source is positioned to illuminate at least a portion of the record, and a linear array camera is positioned to have a field of view of the illuminated portion of the record and orthogonal to the direction of record motion. The elements of the linear array are scanned at increments of motion of the record across the field of view to develop a series of signals corresponding to intensity of light at each element at each scan increment.

  19. MEMS scanning micromirror for optical coherence tomography.

    PubMed

    Strathman, Matthew; Liu, Yunbo; Keeler, Ethan G; Song, Mingli; Baran, Utku; Xi, Jiefeng; Sun, Ming-Ting; Wang, Ruikang; Li, Xingde; Lin, Lih Y

    2015-01-01

    This paper describes an endoscopic-inspired imaging system employing a micro-electromechanical system (MEMS) micromirror scanner to achieve beam scanning for optical coherence tomography (OCT) imaging. Miniaturization of a scanning mirror using MEMS technology can allow a fully functional imaging probe to be contained in a package sufficiently small for utilization in a working channel of a standard gastroesophageal endoscope. This work employs advanced image processing techniques to enhance the images acquired using the MEMS scanner to correct non-idealities in mirror performance. The experimental results demonstrate the effectiveness of the proposed technique.

  20. Lens based adaptive optics scanning laser ophthalmoscope.

    PubMed

    Felberer, Franz; Kroisamer, Julia-Sophie; Hitzenberger, Christoph K; Pircher, Michael

    2012-07-30

    We present an alternative approach for an adaptive optics scanning laser ophthalmoscope (AO-SLO). In contrast to other commonly used AO-SLO instruments, the imaging optics consist of lenses. Images of the fovea region of 5 healthy volunteers are recorded. The system is capable to resolve human foveal cones in 3 out of 5 healthy volunteers. Additionally, we investigated the capability of the system to support larger scanning angles (up to 5°) on the retina. Finally, in order to demonstrate the performance of the instrument images of rod photoreceptors are presented.

  1. High resolution obtained by photoelectric scanning techniques.

    NASA Technical Reports Server (NTRS)

    Hall, J. S.

    1972-01-01

    Several applications of linear scanning of different types of objects are described; examples include double stars, satellites, the Red Spot of Jupiter and a landing site on the moon. This technique allows one to achieve a gain of about an order of magnitude in resolution over conventional photoelectric techniques; it is also effective in providing sufficient data for removing background effects and for the application of deconvolution procedures. Brief consideration is given to two-dimensional scanning, either at the telescope or of electronographic images in the laboratory. It is suggested that some of the techniques described should be given serious consideration for space applications.

  2. Scanning evanescent electro-magnetic microscope

    DOEpatents

    Xiang, Xiao-Dong; Gao, Chen; Schultz, Peter G.; Wei, Tao

    2003-01-01

    A novel scanning microscope is described that uses near-field evanescent electromagnetic waves to probe sample properties. The novel microscope is capable of high resolution imaging and quantitative measurements of the electrical properties of the sample. The inventive scanning evanescent wave electromagnetic microscope (SEMM) can map dielectric constant, tangent loss, conductivity, complex electrical impedance, and other electrical parameters of materials. The quantitative map corresponds to the imaged detail. The novel microscope can be used to measure electrical properties of both dielectric and electrically conducting materials.

  3. Scanning evanescent electro-magnetic microscope

    DOEpatents

    Xiang, Xiao-Dong; Gao, Chen

    2001-01-01

    A novel scanning microscope is described that uses near-field evanescent electromagnetic waves to probe sample properties. The novel microscope is capable of high resolution imaging and quantitative measurements of the electrical properties of the sample. The inventive scanning evanescent wave electromagnetic microscope (SEMM) can map dielectric constant, tangent loss, conductivity, complex electrical impedance, and other electrical parameters of materials. The quantitative map corresponds to the imaged detail. The novel microscope can be used to measure electrical properties of both dielectric and electrically conducting materials.

  4. Dexter: Data Extractor for scanned graphs

    NASA Astrophysics Data System (ADS)

    Demleitner, Markus

    2011-12-01

    The NASA Astrophysics Data System (ADS) now holds 1.3 million scanned pages, containing numerous plots and figures for which the original data sets are lost or inaccessible. The availability of scans of the figures can significantly ease the regeneration of the data sets. For this purpose, the ADS has developed Dexter, a Java applet that supports the user in this process. Dexter's basic functionality is to let the user manually digitize a plot by marking points and defining the coordinate transformation from the logical to the physical coordinate system. Advanced features include automatic identification of axes, tracing lines and finding points matching a template.

  5. Radionuclide scanning in children with rhabdomyosarcoma

    SciTech Connect

    Weinblatt, M.E.; Miller, J.H.

    1981-01-01

    Radionuclide scintigraphy was performed in 46 children with rhabdomyosarcoma. Of the 63 radiologically confirmed sites of bone disease, 76% were detected by /sup 99m/Tc-labeled phosphate uptake. All 15 sites of hepatic involvement and eight of the nine cranial sites of disease exhibited isotope accumulation. Gallium 67 scans showed 57% of the 43 proven sites of disease, including four previously unsuspected areas. Twelve false-positive sites were obtained with gallium. Radionuclide scanning is a valuable aid in the diagnostic evaluation and management of childhood rhabdomyosarcoma.

  6. DepositScan, a Scanning Program to Measure Spray Deposition Distributions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    DepositScan, a scanning program was developed to quickly measure spray deposit distributions on water sensitive papers or Kromekote cards which are widely used for determinations of pesticide spray deposition quality on target areas. The program is installed in a portable computer and works with a ...

  7. The Scanning Theremin Microscope: A Model Scanning Probe Instrument for Hands-On Activities

    ERIC Educational Resources Information Center

    Quardokus, Rebecca C.; Wasio, Natalie A.; Kandel, S. Alex

    2014-01-01

    A model scanning probe microscope, designed using similar principles of operation to research instruments, is described. Proximity sensing is done using a capacitance probe, and a mechanical linkage is used to scan this probe across surfaces. The signal is transduced as an audio tone using a heterodyne detection circuit analogous to that used in…

  8. Scanning probe image wizard: a toolbox for automated scanning probe microscopy data analysis.

    PubMed

    Stirling, Julian; Woolley, Richard A J; Moriarty, Philip

    2013-11-01

    We describe SPIW (scanning probe image wizard), a new image processing toolbox for SPM (scanning probe microscope) images. SPIW can be used to automate many aspects of SPM data analysis, even for images with surface contamination and step edges present. Specialised routines are available for images with atomic or molecular resolution to improve image visualisation and generate statistical data on surface structure.

  9. Scanning probe image wizard: A toolbox for automated scanning probe microscopy data analysis

    NASA Astrophysics Data System (ADS)

    Stirling, Julian; Woolley, Richard A. J.; Moriarty, Philip

    2013-11-01

    We describe SPIW (scanning probe image wizard), a new image processing toolbox for SPM (scanning probe microscope) images. SPIW can be used to automate many aspects of SPM data analysis, even for images with surface contamination and step edges present. Specialised routines are available for images with atomic or molecular resolution to improve image visualisation and generate statistical data on surface structure.

  10. High-speed Lissajous-scan atomic force microscopy: Scan pattern planning and control design issues

    NASA Astrophysics Data System (ADS)

    Bazaei, A.; Yong, Yuen K.; Moheimani, S. O. Reza

    2012-06-01

    Tracking of triangular or sawtooth waveforms is a major difficulty for achieving high-speed operation in many scanning applications such as scanning probe microscopy. Such non-smooth waveforms contain high order harmonics of the scan frequency that can excite mechanical resonant modes of the positioning system, limiting the scan range and bandwidth. Hence, fast raster scanning often leads to image distortion. This paper proposes analysis and design methodologies for a nonlinear and smooth closed curve, known as Lissajous pattern, which allows much faster operations compared to the ordinary scan patterns. A simple closed-form measure is formulated for the image resolution of the Lissajous pattern. This enables us to systematically determine the scan parameters. Using internal model controllers (IMC), this non-raster scan method is implemented on a commercial atomic force microscope driven by a low resonance frequency positioning stage. To reduce the tracking errors due to actuator nonlinearities, higher order harmonic oscillators are included in the IMC controllers. This results in significant improvement compared to the traditional IMC method. It is shown that the proposed IMC controller achieves much better tracking performances compared to integral controllers when the noise rejection performances is a concern.

  11. Apparatus for controlling the scan width of a scanning laser beam

    DOEpatents

    Johnson, G.W.

    1996-10-22

    Swept-wavelength lasers are often used in absorption spectroscopy applications. In experiments where high accuracy is required, it is desirable to continuously monitor and control the range of wavelengths scanned (the scan width). A system has been demonstrated whereby the scan width of a swept ring-dye laser, or semiconductor diode laser, can be measured and controlled in real-time with a resolution better than 0.1%. Scan linearity, or conformity to a nonlinear scan waveform, can be measured and controlled. The system of the invention consists of a Fabry-Perot interferometer, three CAMAC interface modules, and a microcomputer running a simple analysis and proportional-integral control algorithm. With additional modules, multiple lasers can be simultaneously controlled. The invention also includes an embodiment implemented on an ordinary PC with a multifunction plug-in board. 8 figs.

  12. Apparatus for controlling the scan width of a scanning laser beam

    DOEpatents

    Johnson, Gary W.

    1996-01-01

    Swept-wavelength lasers are often used in absorption spectroscopy applications. In experiments where high accuracy is required, it is desirable to continuously monitor and control the range of wavelengths scanned (the scan width). A system has been demonstrated whereby the scan width of a swept ring-dye laser, or semiconductor diode laser, can be measured and controlled in real-time with a resolution better than 0.1%. Scan linearity, or conformity to a nonlinear scan waveform, can be measured and controlled. The system of the invention consists of a Fabry-Perot interferometer, three CAMAC interface modules, and a microcomputer running a simple analysis and proportional-integral control algorithm. With additional modules, multiple lasers can be simultaneously controlled. The invention also includes an embodiment implemented on an ordinary PC with a multifunction plug-in board.

  13. Autofocus method for scanning remote sensing cameras.

    PubMed

    Lv, Hengyi; Han, Chengshan; Xue, Xucheng; Hu, Changhong; Yao, Cheng

    2015-07-10

    Autofocus methods are conventionally based on capturing the same scene from a series of positions of the focal plane. As a result, it has been difficult to apply this technique to scanning remote sensing cameras where the scenes change continuously. In order to realize autofocus in scanning remote sensing cameras, a novel autofocus method is investigated in this paper. Instead of introducing additional mechanisms or optics, the overlapped pixels of the adjacent CCD sensors on the focal plane are employed. Two images, corresponding to the same scene on the ground, can be captured at different times. Further, one step of focusing is done during the time interval, so that the two images can be obtained at different focal plane positions. Subsequently, the direction of the next step of focusing is calculated based on the two images. The analysis shows that the method investigated operates without restriction of the time consumption of the algorithm and realizes a total projection for general focus measures and algorithms from digital still cameras to scanning remote sensing cameras. The experiment results show that the proposed method is applicable to the entire focus measure family, and the error ratio is, on average, no more than 0.2% and drops to 0% by reliability improvement, which is lower than that of prevalent approaches (12%). The proposed method is demonstrated to be effective and has potential in other scanning imaging applications.

  14. Energy conservation, using remote thermal scanning

    NASA Technical Reports Server (NTRS)

    Bowman, R. L.; Jack, J. R.

    1978-01-01

    Airborne thermal infrared scans and thermal maps utilized in NASA's energy conservation program have proven to be efficient cost-effective method for identifying heat losses from building roofs and heating system distribution lines. Method employs commercially available equipment in highly developed way.

  15. Vertically aligned nanostructure scanning probe microscope tips

    DOEpatents

    Guillorn, Michael A.; Ilic, Bojan; Melechko, Anatoli V.; Merkulov, Vladimir I.; Lowndes, Douglas H.; Simpson, Michael L.

    2006-12-19

    Methods and apparatus are described for cantilever structures that include a vertically aligned nanostructure, especially vertically aligned carbon nanofiber scanning probe microscope tips. An apparatus includes a cantilever structure including a substrate including a cantilever body, that optionally includes a doped layer, and a vertically aligned nanostructure coupled to the cantilever body.

  16. 2006 Environmental Scan. ACAATO Archive Document

    ERIC Educational Resources Information Center

    Colleges Ontario, 2006

    2006-01-01

    The Association of Colleges of Applied Arts and Technology of Ontario (ACAATO) is pleased to present this report. The 2006 Environmental Scan provides an aggregate synopsis of the key trends which will impact on Ontario's Colleges of Applied Arts and Technology in the future and will assist colleges in their advocacy and strategic planning…

  17. Scanning tunneling microscopy: Energetics from statistical analysis

    SciTech Connect

    Feibelman, P.J.

    1995-10-15

    The attraction between two Fe atoms adsorbed on Fe(100) should be much too weak to produce the 0.5--0.7-eV bond that has been deduced by analyzing scanning tunneling micrographs. The assumption that adatom diffusion proceeds by the same mechanism at high and low temperatures may be the source of the discrepancy.

  18. The scanning mechanism of eukaryotic translation initiation.

    PubMed

    Hinnebusch, Alan G

    2014-01-01

    In eukaryotes, the translation initiation codon is generally identified by the scanning mechanism, wherein every triplet in the messenger RNA leader is inspected for complementarity to the anticodon of methionyl initiator transfer RNA (Met-tRNAi). Binding of Met-tRNAi to the small (40S) ribosomal subunit, in a ternary complex (TC) with eIF2-GTP, is stimulated by eukaryotic initiation factor 1 (eIF1), eIF1A, eIF3, and eIF5, and the resulting preinitiation complex (PIC) joins the 5' end of mRNA preactivated by eIF4F and poly(A)-binding protein. RNA helicases remove secondary structures that impede ribosome attachment and subsequent scanning. Hydrolysis of eIF2-bound GTP is stimulated by eIF5 in the scanning PIC, but completion of the reaction is impeded at non-AUG triplets. Although eIF1 and eIF1A promote scanning, eIF1 and possibly the C-terminal tail of eIF1A must be displaced from the P decoding site to permit base-pairing between Met-tRNAi and the AUG codon, as well as to allow subsequent phosphate release from eIF2-GDP. A second GTPase, eIF5B, catalyzes the joining of the 60S subunit to produce an 80S initiation complex that is competent for elongation.

  19. The Scanning Electron Microscope and the Archaeologist

    ERIC Educational Resources Information Center

    Ponting, Matthew

    2004-01-01

    Images from scanning electron microscopy are now quite common and they can be of great value in archaeology. Techniques such as secondary electron imaging, backscattered electron imaging and energy-dispersive x-ray analysis can reveal information such as the presence of weevils in grain in Roman Britain, the composition of Roman coins and the…

  20. Interval scanning photomicrography of microbial cell populations.

    NASA Technical Reports Server (NTRS)

    Casida, L. E., Jr.

    1972-01-01

    A single reproducible area of the preparation in a fixed focal plane is photographically scanned at intervals during incubation. The procedure can be used for evaluating the aerobic or anaerobic growth of many microbial cells simultaneously within a population. In addition, the microscope is not restricted to the viewing of any one microculture preparation, since the slide cultures are incubated separately from the microscope.

  1. Visual scanning behavior and pilot workload

    NASA Technical Reports Server (NTRS)

    Tole, J. R.; Stephens, A. T.; Vivaudou, M.; Ephrath, A. R.; Young, L. R.

    1983-01-01

    Sophisticated man machine interaction often requires the human operator to perform a stereotyped scan of various instruments in order to monitor and/or control a system. For situations in which this type of stereotyped behavior exists, such as certain phases of instrument flight, scan pattern was shown to be altered by the imposition of simultaneous verbal tasks. A study designed to examine the relationship between pilot visual scan of instruments and mental workload is described. It was found that a verbal loading task of varying difficulty causes pilots to stare at the primary instrument as the difficulty increases and to shed looks at instruments of less importance. The verbal loading task also affected the rank ordering of scanning sequences. By examining the behavior of pilots with widely varying skill levels, it was suggested that these effects occur most strongly at lower skill levels and are less apparent at high skill levels. A graphical interpretation of the hypothetical relationship between skill, workload, and performance is introduced and modelling results are presented to support this interpretation.

  2. Atypical Saccadic Scanning in Autistic Spectrum Disorder

    ERIC Educational Resources Information Center

    Benson, Valerie; Piper, Jenna; Fletcher-Watson, Sue

    2009-01-01

    Saccadic scanning was examined for typically developing (TD) adults and those with autistic spectrum disorder (ASD) during inspection of the "Repin" picture (Yarbus, A. (1967). "Eye movements and vision". New York: Plenum) under two different viewing instructions: (A) material instructions ("Estimate the material circumstances of the family"); and…

  3. High-pressure differential scanning microcalorimeter.

    PubMed

    Senin, A A; Dzhavadov, L N; Potekhin, S A

    2016-03-01

    A differential scanning microcalorimeter for studying thermotropic conformational transitions of biopolymers at high pressure has been designed. The calorimeter allows taking measurements of partial heat capacity of biopolymer solutions vs. temperature at pressures up to 3000 atm. The principles of operation of the device, methods of its calibration, as well as possible applications are discussed. PMID:27036806

  4. Out-of-Print Digital Scanning.

    ERIC Educational Resources Information Center

    Kellerman, L. Suzanne

    2002-01-01

    Describes the in-house operational procedures developed at the Penn State University libraries to produce facsimiles of hard-to-locate, out-of-print titles using digital scanning technologies. Highlights include identification and selection, costs, copyright issues, interlibrary loan, materials preparation, and future trends. (Author/LRW)

  5. Multiplatform Mobile Laser Scanning: Usability and Performance

    PubMed Central

    Kukko, Antero; Kaartinen, Harri; Hyyppä, Juha; Chen, Yuwei

    2012-01-01

    Mobile laser scanning is an emerging technology capable of capturing three-dimensional data from surrounding objects. With state-of-the-art sensors, the achieved point clouds capture object details with good accuracy and precision. Many of the applications involve civil engineering in urban areas, as well as traffic and other urban planning, all of which serve to make 3D city modeling probably the fastest growing market segment in this field. This article outlines multiplatform mobile laser scanning solutions such as vehicle- and trolley-operated urban area data acquisition, and boat-mounted equipment for fluvial environments. Moreover, we introduce a novel backpack version of mobile laser scanning equipment for surveying applications in the field of natural sciences where the requirements include precision and mobility in variable terrain conditions. In addition to presenting a technical description of the systems, we discuss the performance of the solutions in the light of various applications in the fields of urban mapping and modeling, fluvial geomorphology, snow-cover characterization, precision agriculture, and in monitoring the effects of climate change on permafrost landforms. The data performance of the mobile laser scanning approach is described by the results of an evaluation of the ROAMER on a permanent MLS test field. Furthermore, an in situ accuracy assessment using a field of spherical 3D targets for the newly-introduced Akhka backpack system is conducted and reported on.

  6. Sewer Lateral Electro Scan Field Verification Pilot

    EPA Science Inventory

    Abstract:WERF selected a proposed research project to field test an emerging technology for inspecting sanitary sewer lateral pipes. The technology is called Electro Scan and is used to find defects in laterals that allow the infiltration of groundwater into the lateral. Electro ...

  7. Scanning and focusing mechanisms of METEOSAT radiometer

    NASA Technical Reports Server (NTRS)

    Jouan, J.

    1977-01-01

    Two mechanisms, both of screw-jack type are described. The scanning mechanism, an oil lubricated and sealed unit drives and accurately positions the telescope of the METEOSAT radiometer. The dry lubricated focusing mechanism is used to adjust the focus of this telescope. The METEOSAT program is nearly completed, and the first flight model will be launched at the end of the year.

  8. Compact high-speed scanning lidar system

    NASA Astrophysics Data System (ADS)

    Dickinson, Cameron; Hussein, Marwan; Tripp, Jeff; Nimelman, Manny; Koujelev, Alexander

    2012-06-01

    The compact High Speed Scanning Lidar (HSSL) was designed to meet the requirements for a rover GN&C sensor. The eye-safe HSSL's fast scanning speed, low volume and low power, make it the ideal choice for a variety of real-time and non-real-time applications including: 3D Mapping; Vehicle guidance and Navigation; Obstacle Detection; Orbiter Rendezvous; Spacecraft Landing / Hazard Avoidance. The HSSL comprises two main hardware units: Sensor Head and Control Unit. In a rover application, the Sensor Head mounts on the top of the rover while the Control Unit can be mounted on the rover deck or within its avionics bay. An Operator Computer is used to command the lidar and immediately display the acquired scan data. The innovative lidar design concept was a result of an extensive trade study conducted during the initial phase of an exploration rover program. The lidar utilizes an innovative scanner coupled with a compact fiber laser and high-speed timing electronics. Compared to existing compact lidar systems, distinguishing features of the HSSL include its high accuracy, high resolution, high refresh rate and large field of view. Other benefits of this design include the capability to quickly configure scan settings to fit various operational modes.

  9. Vitamin D status is associated with bone mineral density and bone mineral content in preschool-aged children.

    PubMed

    Hazell, Tom J; Pham, Thu Trang; Jean-Philippe, Sonia; Finch, Sarah L; El Hayek, Jessy; Vanstone, Catherine A; Agellon, Sherry; Rodd, Celia J; Weiler, Hope A

    2015-01-01

    This study examined the associations between vitamin D status, bone mineral content (BMC), areal bone mineral density (aBMD), and markers of calcium homeostasis in preschool-aged children. Children (n=488; age range: 1.8-6.0 y) were randomly recruited from Montreal. The distal forearm was scanned using a peripheral dual-energy X-ray absorptiometry scanner (Lunar PIXI; GE Healthcare, Fairfield, CT). A subset (n=81) had clinical dual-energy X-ray absorptiometry (cDXA) scans (Hologic 4500A Discovery Series) of lumbar spine (LS) 1-4, whole body, and ultradistal forearm. All were assessed for plasma 25-hydroxyvitamin D [25(OH)D] and parathyroid hormone concentrations (Liaison; Diasorin), ionized calcium (ABL80 FLEX; Radiometer Medical A/S), and dietary vitamin D and calcium intakes by survey. Age (p<0.001) and weight-for-age Z-score (p<0.001) were positively associated with BMC and aBMD in all regression models, whereas male sex contributed positively to forearm BMC and aBMD. Having a 25(OH)D concentration of >75 nmol/L positively associated with forearm and whole body BMC and aBMD (p<0.036). Sun index related to (p<0.029) cDXA forearm and LS 1-4 BMC and whole-body aBMD. Nutrient intakes did not relate to BMC or aBMD. In conclusion, higher vitamin D status is linked to higher BMC and aBMD of forearm and whole body in preschool-aged children.

  10. Carbon studies by scanning probe microscopy

    SciTech Connect

    Hendricks, S.A.

    1992-01-01

    Applications of in situ and ex situ scanning probe microscopy (SPM) are described. Scanning probe microscopic methods are based on monitoring the interaction between a tip and substrate. SPM has been used to study various aspects of carbon behavior, including modification of the highly-oriented pyrolytic graphite (HOPG) surface and its users as an electrode. The surface morphology of other forms of carbon, such as carbon black, carbon fibrils, and coal are also studied. Pit formation by thermal gasification of HOPG occurs by a nucleation and lateral growth mechanism. Effects of different surface treatments on pit nucleation are studied by SPM and other methods for reproducible pit production. Characterization of surface properties on the basal and edge planes show effects of thermal treatment. Measurements of the monolayer pit depth show variation with experimental conditions. The electrodeposition and stripping of lead on pitted HOPG has been studied by in situ and ex situ scanning tunneling microscopy (STM) and in situ atomic force microscopy (AFM). Pb deposits preferentially formed at step and pit edges and resembles crystallite growth on a microelectrode disk. The author discusses effects of tip potential on deposition during in situ STM. After stripping, scanning microscopy and XPS indicated that residual Pb species remained on the surface. The selective etching of recessed features of various shapes in HOPG in air was accomplished using STM. Etching of the surface was restricted to the scan area and only occurred with positive biases. Lines with widths as small as 10 nm and squares 25 [times] 25 nm could be formed with monolayer depth (0.34 nm) in the HOPG. Electrochemical STM was used to study in situ the early stages of polyaniline film growth on pitted HOPG. The mechanism of polymerization was studied using three different potential schemes. A growth mechanism for polyaniline on an HOPG electrode is proposed.

  11. Metrological large range scanning probe microscope

    NASA Astrophysics Data System (ADS)

    Dai, Gaoliang; Pohlenz, Frank; Danzebrink, Hans-Ulrich; Xu, Min; Hasche, Klaus; Wilkening, Guenter

    2004-04-01

    We describe a metrological large range scanning probe microscope (LR-SPM) with an Abbe error free design and direct interferometric position measurement capability, aimed at versatile traceable topographic measurements that require nanometer accuracy. A dual-stage positioning system was designed to achieve both a large measurement range and a high measurement speed. This dual-stage system consists of a commercially available stage, referred to as nanomeasuring machine (NMM), with a motion range of 25 mm×25 mm×5 mm along x, y, and z axes, and a compact z-axis piezoelectric positioning stage (compact z stage) with an extension range of 2 μm. The metrological LR-SPM described here senses the surface using a stationary fixed scanning force microscope (SFM) head working in contact mode. During operation, lateral scanning of the sample is performed solely by the NMM. Whereas the z motion, controlled by the SFM signal, is carried out by a combination of the NMM and the compact z stage. In this case the compact z stage, with its high mechanical resonance frequency (greater than 20 kHz), is responsible for the rapid motion while the NMM simultaneously makes slower movements over a larger motion range. To reduce the Abbe offset to a minimum the SFM tip is located at the intersection of three interferometer measurement beams orientated in x, y, and z directions. To improve real time performance two high-end digital signal processing (DSP) systems are used for NMM positioning and SFM servocontrol. Comprehensive DSP firmware and Windows XP-based software are implemented, providing a flexible and user-friendly interface. The instrument is able to perform large area imaging or profile scanning directly without stitching small scanned images. Several measurements on different samples such as flatness standards, nanostep height standards, roughness standards as well as sharp nanoedge samples and 1D gratings demonstrate the outstanding metrological capabilities of the instrument.

  12. Scanning Ion Conductance Microscopy of Live Keratinocytes

    NASA Astrophysics Data System (ADS)

    Hegde, V.; Mason, A.; Saliev, T.; Smith, F. J. D.; McLean, W. H. I.; Campbell, P. A.

    2012-07-01

    Scanning ion conductance microscopy (SICM) is perhaps the least well known technique from the scanning probe microscopy (SPM) family of instruments. As with its more familiar counterpart, atomic force microscopy (AFM), the technique provides high-resolution topographic imaging, with the caveat that target structures must be immersed in a conducting solution so that a controllable ion current may be utilised as the basis for feedback. In operation, this non-contact characteristic of SICM makes it ideal for the study of delicate structures, such as live cells. Moreover, the intrinsic architecture of the instrument, incorporating as it does, a scanned micropipette, lends itself to combination approaches with complementary techniques such as patch-clamp electrophysiology: SICM therefore boasts the capability for both structural and functional imaging. For the present observations, an ICnano S system (Ionscope Ltd., Melbourn, UK) operating in 'hopping mode' was used, with the objective of assessing the instrument's utility for imaging live keratinocytes under physiological buffers. In scans employing cultured HaCaT cells (spontaneously immortalised, human keratinocytes), we compared the qualitative differences of live cells imaged with SICM and AFM, and also with their respective counterparts after chemical fixation in 4% paraformaldehyde. Characteristic surface microvilli were particularly prominent in live cell imaging by SICM. Moreover, time lapse SICM imaging on live cells revealed that changes in the pattern of microvilli could be tracked over time. By comparison, AFM imaging on live cells, even at very low contact forces (scanning speed, however, the intrinsic non-obtrusive nature of

  13. Correcting scan-to-scan response variability for a radiochromic film-based reference dosimetry system

    SciTech Connect

    Lewis, David; Devic, Slobodan

    2015-10-15

    Purpose: In radiochromic film dosimetry systems, measurements are usually obtained from film images acquired on a CCD-based flatbed scanner. The authors investigated factors affecting scan-to-scan response variability leading to increased dose measurement uncertainty. Methods: The authors used flatbed document scanners to repetitively scan EBT3 radiochromic films exposed to doses 0–1000 cGy, together with three neutral density filters and three blue optical filters. Scanning was performed under two conditions: scanner lid closed and scanner lid opened/closed between scans. The authors also placed a scanner in a cold room at 9 °C and later in a room at 22 °C and scanned EBT3 films to explore temperature effects. Finally, the authors investigated the effect of altering the distance between the film and the scanner’s light source. Results: Using a measurement protocol to isolate the contribution of the CCD and electronic circuitry of the scanners, the authors found that the standard deviation of response measurements for the EBT3 film model was about 0.17% for one scanner and 0.09% for the second. When the lid of the first scanner was opened and closed between scans, the average scan-to-scan difference of responses increased from 0.12% to 0.27%. Increasing the sample temperature during scanning changed the RGB response values by about −0.17, −0.14, and −0.05%/°C, respectively. Reducing the film-to-light source distance increased the RBG response values about 1.1, 1.3, and 1.4%/mm, respectively. The authors observed that films and film samples were often not flat with some areas up to 8 mm away from the scanner’s glass window. Conclusions: In the absence of measures to deal with the response irregularities, each factor the authors investigated could lead to dose uncertainty >2%. Those factors related to the film-to-light source distance could be particularly impactful since the authors observed many instances where the curl of film samples had the

  14. Comparison of dimensional accuracy of digital dental models produced from scanned impressions and scanned stone casts

    NASA Astrophysics Data System (ADS)

    Subeihi, Haitham

    Introduction: Digital models of dental arches play a more and more important role in dentistry. A digital dental model can be generated by directly scanning intraoral structures, by scanning a conventional impression of oral structures or by scanning a stone cast poured from the conventional impression. An accurate digital scan model is a fundamental part for the fabrication of dental restorations. Aims: 1. To compare the dimensional accuracy of digital dental models produced by scanning of impressions versus scanning of stone casts. 2. To compare the dimensional accuracy of digital dental models produced by scanning of impressions made of three different materials (polyvinyl siloxane, polyether or vinyl polyether silicone). Methods and Materials: This laboratory study included taking addition silicone, polyether and vinyl polyether silicone impressions from an epoxy reference model that was created from an original typodont. Teeth number 28 and 30 on the typodont with a missing tooth number 29 were prepared for a metal-ceramic three-unit fixed dental prosthesis with tooth #29 being a pontic. After tooth preparation, an epoxy resin reference model was fabricated by duplicating the typodont quadrant that included the tooth preparations. From this reference model 12 polyvinyl siloxane impressions, 12 polyether impressions and 12 vinyl polyether silicone impressions were made. All 36 impressions were scanned before pouring them with dental stone. The 36 dental stone casts were, in turn, scanned to produce digital models. A reference digital model was made by scanning the reference model. Six groups of digital models were produced. Three groups were made by scanning of the impressions obtained with the three different materials, the other three groups involved the scanning of the dental casts that resulted from pouring the impressions made with the three different materials. Groups of digital models were compared using Root Mean

  15. Pointed science scan platforms. [for remote directional satellite instrumentation systems

    NASA Technical Reports Server (NTRS)

    Ward, R. S.

    1978-01-01

    Two examples of science scan platform mechanization concepts are presented to familiarize the reader with today's planetary scan platform technology. The first example is the Voyager scan platform, which will demonstrate the traditional approach to scan pointing from planetary vehicles. Although this conventional approach may be familiar to many, the control law implemented in the scan positioning loop is a new and interesting one. It is called 'Zero Crosser + Terminal Control'. The other example marks the beginning of a new generation of planetary scan pointing systems. It is the Galileo scan platform which will be inertially stabilized and decoupled from spacecraft motion.

  16. Council Approves Scanning All Back Issues

    NASA Astrophysics Data System (ADS)

    2004-07-01

    At its last meeting, the 2002-2004 Council, which oversaw the first 2 years of electronic publishing by the Union, authorized funds to scan all back issues of journals, books, and the archival material from Eos and Transactions. In accepting the proposal of the Publications Committee, Council noted that providing the means to deliver all back issues is a fitting conclusion to the transition to electronic publishing. Expenditures of up to $1.1 million were authorized for the scanning project, and for creating searchable abstracts of all back material, and for several other smaller projects. The money comes from the Electronic Publishing Development Fund, which had been built in the 1990s specifically to assure the financial underpinning for the electronic publishing transition. Members should start seeing the fruits of this work in 2006.

  17. Environmental scanning electron microscope (ESEM). Final report

    SciTech Connect

    Marder, A.; Barmak, K.; Williams, D.

    1998-11-01

    The Environmental Scanning Electron Microscope (ESEM) was acquired by a grant from the Department of Energy University Research Instrumentation Program and matching funds from Lehigh University and industry. The equipment is installed as part of the electron microscopy laboratories and is being utilized on a regular basis. Over 20 graduate and undergraduate students from the Department of Materials Science and Engineering as well as other department in the University have included this instrument in their research. In addition, the ESEM has been used in several courses including MAT 427 -- Advanced Scanning Electron Microscopy, a graduate course offered every other year. Examples are given of how the ESEM has been included in the research programs.

  18. Hardware for digitally controlled scanned probe microscopes

    NASA Astrophysics Data System (ADS)

    Clark, S. M.; Baselt, D. R.; Spence, C. F.; Youngquist, M. G.; Baldeschwieler, J. D.

    1992-10-01

    The design and implementation of a flexible and modular digital control and data acquisition system for scanned probe microscopes (SPMs) is presented. The measured performance of the system shows it to be capable of 14-bit data acquisition at a 100-kHz rate and a full 18-bit output resolution resulting in less than 0.02-Å rms position noise while maintaining a scan range in excess of 1 μm in both the X and Y dimensions. This level of performance achieves the goal of making the noise of the microscope control system an insignificant factor for most experiments. The adaptation of the system to various types of SPM experiments is discussed. Advances in audio electronics and digital signal processors have made the construction of such high performance systems possible at low cost.

  19. Scanning gate imaging in confined geometries

    NASA Astrophysics Data System (ADS)

    Steinacher, R.; Kozikov, A. A.; Rössler, C.; Reichl, C.; Wegscheider, W.; Ensslin, K.; Ihn, T.

    2016-02-01

    This article reports on tunable electron backscattering investigated with the biased tip of a scanning force microscope. Using a channel defined by a pair of Schottky gates, the branched electron flow of ballistic electrons injected from a quantum point contact is guided by potentials of a tunable height well below the Fermi energy. The transition from injection into an open two-dimensional electron gas to a strongly confined channel exhibits three experimentally distinct regimes: one in which branches spread unrestrictedly, one in which branches are confined but the background conductance is affected very little, and one where the branches have disappeared and the conductance is strongly modified. Classical trajectory-based simulations explain these regimes at the microscopic level. These experiments allow us to understand under which conditions branches observed in scanning gate experiments do or do not reflect the flow of electrons.

  20. Microprocessor-controlled scanning densitometer system

    SciTech Connect

    Shurtliff, R.W.

    1980-04-01

    An Automated Scanning Densitometer System has been developed by uniting a microprocessor with a low energy x-ray densitometer system. The microprocessor controls the detector movement, provides self-calibration, compensates raw readings to provide time-linear output, controls both data storage and the host computer interface, and provides measurement output in engineering units for immediate reading. The densitometer, when used in a scanning mode, is a precision reference instrument that provides chordal average density measurements over the cross section of a pipe under steady-state flow conditions. Results have shown an improvement over the original densitometer in reliability and repeatability of the system, an a factor-of-five improvement in accuracy.

  1. Preliminary design study. Shuttle modular scanning spectroradiometer

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Fundamental concepts on which to base a detailed design for a Shuttle Modular Scanning Spectroradiometer were developed, and a preliminary design is presented. The recommended design features modularity and flexibility. It includes a 75-cm f/1.7-telescope assembly in an all-reflective Schmidt configuration, a solid state scan system (pushbroom) with high resolution over a 15 deg field of view, and ten detector channels covering the spectral range from 0.45 to 12.5 micrometers. It uses charge transfer device techniques to accommodate a large number of detector elements for earth observation measurements. Methods for in-flight radiometric calibration, for image motion compensation, and for data processing are described. Recommendations for ground support equipment are included, and interfaces with the shuttle orbiter vehicle are illustrated.

  2. Radionuclide bone scanning in giant cell tumor

    SciTech Connect

    Van Nostrand, D.; Madewell, J.E.; McNiesh, L.M.; Kyle, R.W.; Sweet, D.

    1986-03-01

    Radionuclide bone scan findings are described and correlated with pathology in 23 patients with giant cell tumor (GCT) of the bone. The degree of radionuclide activity was markedly increased in 20 (87%), minimally increased in three (13%), and decreased in none of the patients. Of the 23 patients with increased radioactivity, the pattern was diffuse in 11 (48%) and doughnut in 12 (52%). Extended patterns of radioactivity were present in 19 of 22 patients; however, none were associated with true tumor extension. Bone scanning did not aid in the detection of GCT, was nonspecific, and did not differentiate benign from malignant GCT. Although radioactivity extended beyond the radiographic abnormality in the majority of patients, this was most likely secondary to other bony abnormalities or local and/or regional hyperemia, and caution should be taken in ascribing this extension to either tumor or metastasis.

  3. High-speed massively parallel scanning

    DOEpatents

    Decker, Derek E.

    2010-07-06

    A new technique for recording a series of images of a high-speed event (such as, but not limited to: ballistics, explosives, laser induced changes in materials, etc.) is presented. Such technique(s) makes use of a lenslet array to take image picture elements (pixels) and concentrate light from each pixel into a spot that is much smaller than the pixel. This array of spots illuminates a detector region (e.g., film, as one embodiment) which is scanned transverse to the light, creating tracks of exposed regions. Each track is a time history of the light intensity for a single pixel. By appropriately configuring the array of concentrated spots with respect to the scanning direction of the detection material, different tracks fit between pixels and sufficient lengths are possible which can be of interest in several high-speed imaging applications.

  4. Environmental scanning electron microscopy in cell biology.

    PubMed

    McGregor, J E; Staniewicz, L T L; Guthrie Neé Kirk, S E; Donald, A M

    2013-01-01

    Environmental scanning electron microscopy (ESEM) (1) is an imaging technique which allows hydrated, insulating samples to be imaged under an electron beam. The resolution afforded by this technique is higher than conventional optical microscopy but lower than conventional scanning electron microscopy (CSEM). The major advantage of the technique is the minimal sample preparation needed, making ESEM quick to use and the images less susceptible to the artifacts that the extensive sample preparation usually required for CSEM may introduce. Careful manipulation of both the humidity in the microscope chamber and the beam energy are nevertheless essential to prevent dehydration and beam damage artifacts. In some circumstances it is possible to image live cells in the ESEM (2).In the following sections we introduce the fundamental principles of ESEM imaging before presenting imaging protocols for plant epidermis, mammalian cells, and bacteria. In the first two cases samples are imaged using the secondary electron (topographic) signal, whereas a transmission technique is employed to image bacteria.

  5. Scanning Josephson spectroscopy on the atomic scale

    NASA Astrophysics Data System (ADS)

    Randeria, Mallika T.; Feldman, Benjamin E.; Drozdov, Ilya K.; Yazdani, Ali

    2016-04-01

    The Josephson effect provides a direct method to probe the strength of the pairing interaction in superconductors. By measuring the phase fluctuating Josephson current between a superconducting tip of a scanning tunneling microscope and a BCS superconductor with isolated magnetic adatoms on its surface, we demonstrate that the spatial variation of the pairing order parameter can be characterized on the atomic scale. This system provides an example where the local pairing potential suppression is not directly reflected in the spectra measured via quasiparticle tunneling. Spectroscopy with such superconducting tips also shows signatures of previously unexplored Andreev processes through individual impurity-bound Shiba states. The atomic resolution achieved here establishes scanning Josephson spectroscopy as a promising technique for the study of novel superconducting phases.

  6. A spatial scan statistic for multinomial data

    PubMed Central

    Jung, Inkyung; Kulldorff, Martin; Richard, Otukei John

    2014-01-01

    As a geographical cluster detection analysis tool, the spatial scan statistic has been developed for different types of data such as Bernoulli, Poisson, ordinal, exponential and normal. Another interesting data type is multinomial. For example, one may want to find clusters where the disease-type distribution is statistically significantly different from the rest of the study region when there are different types of disease. In this paper, we propose a spatial scan statistic for such data, which is useful for geographical cluster detection analysis for categorical data without any intrinsic order information. The proposed method is applied to meningitis data consisting of five different disease categories to identify areas with distinct disease-type patterns in two counties in the U.K. The performance of the method is evaluated through a simulation study. PMID:20680984

  7. Voice coil-based scanning probe microscopy

    PubMed Central

    2012-01-01

    We present a novel system for large-area scanning probe microscopy (SPM) measurements based on minimum counter-force linear guidance mechanisms, voice coils, interferometers and fuzzy logic-based feedback loop electronics. It is shown that voice coil-based actuation combined with interferometry can be a good alternative to piezoceramic positioning systems, providing fast and still sufficient, precise displacements which range from nanometers to millimeters. Using fuzzy logic feedback control, it can be actuated even with only a few low-cost components, like a cheap single-chip microcontroller. As the final positioning resolution can be made independent on the electronics output resolution, the system can reach high positioning resolution even on very large scan sizes. This is a key prerequisite for developing novel generations of SPMs that would combine, in a very large range, with high-speed imaging. PMID:22720756

  8. Macroscopic model of scanning force microscope

    DOEpatents

    Guerra-Vela, Claudio; Zypman, Fredy R.

    2004-10-05

    A macroscopic version of the Scanning Force Microscope is described. It consists of a cantilever under the influence of external forces, which mimic the tip-sample interactions. The use of this piece of equipment is threefold. First, it serves as direct way to understand the parts and functions of the Scanning Force Microscope, and thus it is effectively used as an instructional tool. Second, due to its large size, it allows for simple measurements of applied forces and parameters that define the state of motion of the system. This information, in turn, serves to compare the interaction forces with the reconstructed ones, which cannot be done directly with the standard microscopic set up. Third, it provides a kinematics method to non-destructively measure elastic constants of materials, such as Young's and shear modules, with special application for brittle materials.

  9. Laser scanning system for object monitoring

    DOEpatents

    McIntyre, Timothy James [Knoxville, TN; Maxey, Lonnie Curtis [Powell, TN; Chiaro, Jr; John, Peter [Clinton, TN

    2008-04-22

    A laser scanner is located in a fixed position to have line-of-sight access to key features of monitored objects. The scanner rapidly scans pre-programmed points corresponding to the positions of retroreflecting targets affixed to the key features of the objects. The scanner is capable of making highly detailed scans of any portion of the field of view, permitting the exact location and identity of targets to be confirmed. The security of an object is verified by determining that the cooperative target is still present and that its position has not changed. The retroreflecting targets also modulate the reflected light for purposes of returning additional information back to the location of the scanner.

  10. Quaternions for Galileo scan platform control

    NASA Technical Reports Server (NTRS)

    Breckenridge, W. G.; Man, G. K.

    1984-01-01

    The application of quaternions for the articulation control of the Galileo scan platform is presented in this paper. The purpose of selecting quaternions is to minimize onboard computation time and program size. Attention has been focused on performing inertial pointing while the spacecraft is in a dual spin configuration. Target quaternion and relative target quaternion are introduced and used to specify the target position of the scan platform for point-to-point absolute slews and mosaic relative slews, respectively. The pointing error of the platform is represented by an error quaternion which is converted into gimbal angular errors defining the attitude change. For path control, a moving target quaternion is generated; the corresponding tracking error quaternion and the related spacecraft motion compensation capability are also addressed. A sample slew case is used to demonstrate the implementation of these concepts.

  11. Soft stylus probes for scanning electrochemical microscopy.

    PubMed

    Cortés-Salazar, Fernando; Träuble, Markus; Li, Fei; Busnel, Jean-Marc; Gassner, Anne-Laure; Hojeij, Mohamad; Wittstock, Gunther; Girault, Hubert H

    2009-08-15

    A soft stylus microelectrode probe has been developed to carry out scanning electrochemical microscopy (SECM) of rough, tilted, and large substrates in contact mode. It is fabricated by first ablating a microchannel in a polyethylene terephthalate thin film and filling it with a conductive carbon ink. After curing the carbon track and lamination with a polymer film, the V-shaped stylus was cut thereby forming a probe, with the cross section of the carbon track at the tip being exposed either by UV-photoablation machining or by blade cutting followed by polishing to produce a crescent moon-shaped carbon microelectrode. The probe properties have been assessed by cyclic voltammetry, approach curves, and line scans over electrochemically active and inactive substrates of different roughness. The influence of probe bending on contact mode imaging was then characterized using simple patterns. Boundary element method simulations were employed to rationalize the distance-dependent electrochemical response of the soft stylus probes. PMID:19630394

  12. CS-Studio Scan System Parallelization

    SciTech Connect

    Kasemir, Kay; Pearson, Matthew R

    2015-01-01

    For several years, the Control System Studio (CS-Studio) Scan System has successfully automated the operation of beam lines at the Oak Ridge National Laboratory (ORNL) High Flux Isotope Reactor (HFIR) and Spallation Neutron Source (SNS). As it is applied to additional beam lines, we need to support simultaneous adjustments of temperatures or motor positions. While this can be implemented via virtual motors or similar logic inside the Experimental Physics and Industrial Control System (EPICS) Input/Output Controllers (IOCs), doing so requires a priori knowledge of experimenters requirements. By adding support for the parallel control of multiple process variables (PVs) to the Scan System, we can better support ad hoc automation of experiments that benefit from such simultaneous PV adjustments.

  13. Kinematic analysis of conically scanned environmental properties

    NASA Technical Reports Server (NTRS)

    Wilkerson, Thomas D. (Inventor); Sanders, Jason A. (Inventor); Andrus, Ionio Q. (Inventor)

    2003-01-01

    A method for determining the velocity of features such as wind. The method preferably includes producing sensor signals and projecting the sensor signals sequentially along lines lying on the surface of a cone. The sensor signals may be in the form of lidar, radar or sonar for example. As the sensor signals are transmitted, the signals contact objects and are backscattered. The backscattered sensor signals are received to determine the location of objects as they pass through the transmission path. The speed and direction the object is moving may be calculated using the backscattered data. The data may be plotted in a two dimensional array with a scan angle on one axis and a scan time on the other axis. The prominent curves that appear in the plot may be analyzed to determine the speed and direction the object is traveling.

  14. Correlates of Use of Antifracture Therapy in Older Women with Low Bone Mineral Density

    PubMed Central

    Ryder, Kathryn M; Shorr, Ronald I; Tylavsky, Frances A; Bush, Andrew J; Bauer, Douglas C; Simonsick, Eleanor M; Strotmeyer, Elsa S; Harris, Tamara B

    2006-01-01

    BACKGROUND Guidelines exist for treatment of low bone mineral density (BMD). Little is known about patient characteristics associated with use of treatment. OBJECTIVES To determine patient-related correlates of medication use following screening dual x-ray absorptiometry (DXA) of older adults. DESIGN Secondary analysis of a prospective cohort study. SETTING Pittsburgh, PA and Memphis, TN. PARTICIPANTS Community-dwelling women between the ages 70 and 79 years enrolled in the Health, Aging, and Body Composition (Health ABC) Study. MEASUREMENTS Risk factors for fracture and BMD of the hip were assessed at baseline. Patients and their community physicians were supplied the results of the DXA scan. Prescription and over-the-counter medication use was collected at annual exams for 2 years. RESULTS Of 1,584 women enrolled in Health ABC, 378 had an indication for antifracture therapy and were not receiving such treatment at baseline. By the second annual follow-up examination, prescription antiresorptive medication was reported in 49 (13.0%), whereas 65 (17.2%) received calcium and/or vitamin D supplementation. In adjusted models, the strongest predictor for use of any antifracture medicine was presence of osteoporosis [vs osteopenia, odds ratio (OR), 2.9 (1.7 to 4.7)], white race [OR, 2.6 (1.5 to 4.8)], and receipt of the flu shot [OR, 2.2 (1.3 to 3.8)]. Neither a history of falls nor prior fracture was associated with use of antifracture medications. CONCLUSION Even when physicians of study participants were provided with DXA scan results, 70% of older high-functioning women with an indication for therapy did not start or remain on an antifracture therapy. Substantial room for improvement exists in fracture prevention following a diagnosis of low BMD—especially among women with a history of falls, prior fractures, and among black women. PMID:16808749

  15. Body composition in human infants at birth and postnatally.

    PubMed

    Koo, W W; Walters, J C; Hockman, E M

    2000-09-01

    The predictive values of anthropometric measurements, race, gender, gestational and postnatal ages, and season at birth and at study for the total body dual energy X-ray absorptiometry (DXA)-derived lean mass (LM), fat mass (FM) and fat mass as a percentage of body weight (%FM) were determined in 214 singleton appropriate birth weight for gestational age infants [101 Caucasian (60 boys, 41 girls) and 113 African American (55 boys, 58 girls)]. Gestational ages were 27-42 wk and the infants were studied between birth and 391 d, weighing between 851 and 13446 g. In addition, predictive value of body weight, LM and FM for DXA bone measurements was also determined. Scan acquisition used Hologic QDR 1000/W densitometer and infant platform and scans without significant movement artifacts were analyzed using software 5.64p. Body weight, length, gender and postnatal age were significant predictors of LM (adjusted R:(2) >0. 94) and FM (adjusted R:(2) >0.85). Physiologic variables had little predictive value for %FM except in the newborns (adjusted R:(2) 0. 69). Body weight was the dominant predictor of LM and FM, although length had similar predictive value for LM with increasing postnatal age. Female infants had less LM and more FM throughout infancy (P: < 0.01). LM or FM offered no advantage over body weight in the prediction of bone mass measurements. DXA is a useful means with which to determine body composition, and our data are important in the design and assessment of nutritional intervention studies.

  16. 47 CFR 15.121 - Scanning receivers and frequency converters used with scanning receivers.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...; replacing a plug-in semiconductor chip; or programming a semiconductor chip using special access codes or an external device, such as a personal computer. Scanning receivers, and frequency converters designed for...

  17. 47 CFR 15.121 - Scanning receivers and frequency converters used with scanning receivers.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...; replacing a plug-in semiconductor chip; or programming a semiconductor chip using special access codes or an external device, such as a personal computer. Scanning receivers, and frequency converters designed for...

  18. 47 CFR 15.121 - Scanning receivers and frequency converters used with scanning receivers.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...; replacing a plug-in semiconductor chip; or programming a semiconductor chip using special access codes or an external device, such as a personal computer. Scanning receivers, and frequency converters designed for...

  19. 47 CFR 15.121 - Scanning receivers and frequency converters used with scanning receivers.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...; replacing a plug-in semiconductor chip; or programming a semiconductor chip using special access codes or an external device, such as a personal computer. Scanning receivers, and frequency converters designed for...

  20. 47 CFR 15.121 - Scanning receivers and frequency converters used with scanning receivers.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...; replacing a plug-in semiconductor chip; or programming a semiconductor chip using special access codes or an external device, such as a personal computer. Scanning receivers, and frequency converters designed for...