The Experts below are selected from a list of 180 Experts worldwide ranked by ideXlab platform
Shawn K Davison - One of the best experts on this subject based on the ideXlab platform.
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Densitometer specific differences in the correlation between body mass index and lumbar spine trabecular bone score
Journal of Clinical Densitometry, 2017Co-Authors: Gillian Mazzetti, Claudie Berger, William D Leslie, Didier Hans, Lisa Langsetmo, David A Hanley, Christopher S Kovacs, Jerrilyn C Prior, Stephanie M Kaiser, Shawn K DavisonAbstract:Trabecular bone score (TBS) is a gray-level texture measure derived from lumbar spine dual-energy X-ray absorptiometry (DXA) images that predicts fractures independent of bone mineral density (BMD). Increased abdominal soft tissue in individuals with elevated body mass index (BMI) absorbs more X-rays during image acquisition for BMD measurement and must be accommodated by the TBS algorithm. We aimed to determine if the relationship between BMI and TBS varied between 2 major manufacturers' Densitometers, because different Densitometers accommodate soft tissues differently. We identified 1919 women and 811 men, participants of the Canadian Multicentre Osteoporosis Study, aged ≥40 yr with lumbar spine DXA scans acquired on GE Lunar (4 centers) or Hologic (3 centers) Densitometers at year 10 of follow-up. TBS was calculated for L1-L4 (TBS iNsight® software, version 2.1). A significant negative correlation between TBS and BMI was observed when TBS measurements were performed on Hologic Densitometers in men (Pearson r = -0.36, p <0.0001) and in women (Pearson r = -0.33, p <0.0001); significant correlations were not seen when TBS was measured on GE Lunar Densitometers (Pearson r = 0.00 in men, Pearson r = -0.02 in women). Age-adjusted linear regression models confirmed significant interactions between BMI and Densitometer manufacturer for both men and women (p < 0.0001). In contrast, comparable positive correlations were observed between BMD and BMI on both Hologic and GE Lunar Densitometers in men and women. In conclusion, BMI significantly affects TBS values in men and women when measured on Hologic but not GE Lunar Densitometers. This finding has implications for clinical and research applications of TBS, especially when TBS is measured sequentially on DXA Densitometers from different manufacturers or when results from different machines are pooled for analysis.
Richard Eastell - One of the best experts on this subject based on the ideXlab platform.
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comparison of rates of bone loss from the spine measured using two manufacturers Densitometers
Journal of Bone and Mineral Research, 2009Co-Authors: N F A Peel, Richard EastellAbstract:: Measurements of bone mineral density of the lumbar spine (LS-BMD) by dual-energy X-ray absorptiometry (DXA), made using different manufacturers' Densitometers, differ by approximately 15%. The aim of this study was to compare the rate of bone loss from the lumbar spine measured using two manufacturers' Densitometers. LS-BMD (vertebrae L2-L4) was measured using both a Lunar DPX and a Hologic QDR 1000/W in 17 postmenopausal women at baseline and 2 years. The mean rate of change of LS-BMD made using the two Densitometers did not differ (DPX -0.54% per year; QDR -0.17% per year). although rates of change of LS-BMD measured using the two Densitometers correlated (r = 0.47, p = 0.05), the variance of the rates of loss differed such that, in individual subjects, the difference between the rates of loss of LS-BMD, measured using the two Densitometers, was related to the average rate of loss (r = 0.61, p = 0.009). For both Densitometers, as bone mineral content (BMC) increased, the measured area also increased, leading to an underestimate of change in bone mineral density (BMD). This relation differed between the two Densitometers such that the change in BMD was underestimated to a greater extent by QDR. We conclude that in the context of multicenter studies it may not be possible to directly combine data on the rate of bone loss acquired using different manufacturers' Densitometers.
Gillian Mazzetti - One of the best experts on this subject based on the ideXlab platform.
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Densitometer specific differences in the correlation between body mass index and lumbar spine trabecular bone score
Journal of Clinical Densitometry, 2017Co-Authors: Gillian Mazzetti, Claudie Berger, William D Leslie, Didier Hans, Lisa Langsetmo, David A Hanley, Christopher S Kovacs, Jerrilyn C Prior, Stephanie M Kaiser, Shawn K DavisonAbstract:Trabecular bone score (TBS) is a gray-level texture measure derived from lumbar spine dual-energy X-ray absorptiometry (DXA) images that predicts fractures independent of bone mineral density (BMD). Increased abdominal soft tissue in individuals with elevated body mass index (BMI) absorbs more X-rays during image acquisition for BMD measurement and must be accommodated by the TBS algorithm. We aimed to determine if the relationship between BMI and TBS varied between 2 major manufacturers' Densitometers, because different Densitometers accommodate soft tissues differently. We identified 1919 women and 811 men, participants of the Canadian Multicentre Osteoporosis Study, aged ≥40 yr with lumbar spine DXA scans acquired on GE Lunar (4 centers) or Hologic (3 centers) Densitometers at year 10 of follow-up. TBS was calculated for L1-L4 (TBS iNsight® software, version 2.1). A significant negative correlation between TBS and BMI was observed when TBS measurements were performed on Hologic Densitometers in men (Pearson r = -0.36, p <0.0001) and in women (Pearson r = -0.33, p <0.0001); significant correlations were not seen when TBS was measured on GE Lunar Densitometers (Pearson r = 0.00 in men, Pearson r = -0.02 in women). Age-adjusted linear regression models confirmed significant interactions between BMI and Densitometer manufacturer for both men and women (p < 0.0001). In contrast, comparable positive correlations were observed between BMD and BMI on both Hologic and GE Lunar Densitometers in men and women. In conclusion, BMI significantly affects TBS values in men and women when measured on Hologic but not GE Lunar Densitometers. This finding has implications for clinical and research applications of TBS, especially when TBS is measured sequentially on DXA Densitometers from different manufacturers or when results from different machines are pooled for analysis.
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Densitometer-Specific Differences in the Correlation Between Body Mass Index and Lumbar Spine Trabecular Bone Score
Journal of clinical densitometry : the official journal of the International Society for Clinical Densitometry, 2016Co-Authors: Gillian Mazzetti, Claudie Berger, William D Leslie, Didier Hans, Lisa Langsetmo, David A Hanley, Christopher S Kovacs, Jerrilyn C Prior, Stephanie M Kaiser, K. Shawn DavisonAbstract:Trabecular bone score (TBS) is a gray-level texture measure derived from lumbar spine dual-energy X-ray absorptiometry (DXA) images that predicts fractures independent of bone mineral density (BMD). Increased abdominal soft tissue in individuals with elevated body mass index (BMI) absorbs more X-rays during image acquisition for BMD measurement and must be accommodated by the TBS algorithm. We aimed to determine if the relationship between BMI and TBS varied between 2 major manufacturers' Densitometers, because different Densitometers accommodate soft tissues differently. We identified 1919 women and 811 men, participants of the Canadian Multicentre Osteoporosis Study, aged ≥40 yr with lumbar spine DXA scans acquired on GE Lunar (4 centers) or Hologic (3 centers) Densitometers at year 10 of follow-up. TBS was calculated for L1-L4 (TBS iNsight® software, version 2.1). A significant negative correlation between TBS and BMI was observed when TBS measurements were performed on Hologic Densitometers in men (Pearson r = -0.36, p
Neil Binkley - One of the best experts on this subject based on the ideXlab platform.
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spine trabecular bone score precision a comparison between ge lunar standard and high resolution Densitometers
Journal of Clinical Densitometry, 2015Co-Authors: Diane Krueger, Jessie Libber, Neil BinkleyAbstract:Abstract Trabecular bone score (TBS) is related to microarchitecture and fracture risk independently of bone mineral density (BMD) and clinical risk factors. Widespread clinical TBS use requires documentation of reproducibility and ideally comparability across scanners. This study evaluated TBS reproducibility and explored differences between Lunar Prodigy and iDXA Densitometers. Reproducibility was assessed from replicate scans in 210 men and women participating in various dual-energy X-ray absorptiometry (DXA) precision assessments. iDXA-to-Prodigy comparability was evaluated using 155 participants from 3 study groups. L1–L4 BMD and TBS precision was similar on iDXA and Prodigy (BMD coefficient of variation = 1.9% and 1.5% and TBS coefficient of variation = 1.4% and 1.6%, respectively). Precision did not differ between men and women; however, between-technologist differences ( p R 2 = 0.85 with bias of −0.010 TBS units). Agreement was less robust comparing Prodigy with iDXA instruments (TBS R 2 : 0.72–0.81 with biases of 0.012–0.034 TBS units). In conclusion, TBS precision is comparable to that of BMD and does not differ between men and women. Additionally, in these cohorts, slight TBS differences were observed between iDXA and Prodigy scans. These data suggest a potential difference between Densitometer models perhaps due to higher iDXA image resolution.
G R Gluckman - One of the best experts on this subject based on the ideXlab platform.
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predicting optical Densitometer response as a function of light source characteristics for radiochromic film dosimetry
Medical Physics, 1997Co-Authors: L E Reinstein, G R Gluckman, Howard I AmolsAbstract:Various forms of GAFChromic (GC) film have been used for several years as radiographic media for measuring dose distributions of brachytherapysources and small radiation fields. In order to optimize the measurement sensitivity and thus improve precision, we describe a method to calculate the dose response curves (net optical density at a give wavelength or spectrum versus absorbed dose) for different Densitometer light sources using measured GC film absorption spectra. Comparison with measurements on the latest version of GC film (model MD-55-2) using four types of Densitometers [He-Ne laser, broadband (white light) Densitometer, and two LED (red-light) filtered Densitometers] confirm the accuracy of this predictive model. The linearity and sensitivity of the dose response curves are found to be highly dependent on the light sourcespectrum. Initial slope is a function of the average weighted absorbance. Early saturation and decreased linearity of the dose response curves are ascribed to the nonuniform transmission of the light source through the GC film. We found that an LED (red-light) source with a narrow bandpass filter centered at 671 nm near the major absorption peak achieves nearly the maximum possible sensitivity (almost four times more sensitive than He-Ne laser, 632.8 nm) and may be suitable for in vivodosimetry.
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comparison of dose response of radiochromic film measured with he ne laser broadband and filtered light Densitometers
Medical Physics, 1997Co-Authors: Lawrence E. Reinstein, G R GluckmanAbstract:Dose response curves for GAFChromic MD-55-2 film were measured using three different Densitometer systems: a He-Ne laser Densitometer, a broadband (white light) Densitometer, and a filtered red light Densitometer. These were found to differ significantly; the dose needed to achieve a net optical density of 1 (DNOD1) was greater than 100 Gy for the white light Densitometer, 56 Gy for the He-Ne Densitometer, and only 14.8 Gy for the filtered red light Densitometer. This represents approximately a fourfold increase in response for the filtered red light versus the He-Ne laser Densitometer, which is a significant improvement. For some patient prescriptions this enables us to achieve an accuracy and precision sufficient to verify daily dose to within 5%.