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End Ones CHIR-99021 Difficulties Permanently|Once And For All|For Good}

For femoral scans, the superior margin of the fat layering bags was positioned 1 inch below the iliac crest. The study was approved by the institutional review board of Massachusetts General Hospital and all subjects provided written informed consent. DXA scans were performed on a Hologic Discovery A densitometer (Hologic Inc., Waltham, MA, USA). Enhanced mode was used during scan acquisition, which involves slower acquisition of images to improve image quality. Least significant change (LSC) was calculated as follows: LSC?=?1.96 CV, where CV represents the coefficient of variation. Based on prior measurements, our short-term precision CV for in vivo measurements is 1.6% for the Selleck CHIR 99021 posterior�Canterior lumbar spine, 2.4% for the femoral neck, and 1.1% for the total hip,13 corresponding to an LSC of 4.4%, 6.7%, and 3.0%, respectively. Coverage of the area of interest by fat bags was confirmed during postprocessing analysis. Analysis of lumbar spine scans in human subjects was restricted to L2�CL4 because of inconsistent coverage of L1 by the fat bags. Trabecular BMD of the lumbar spine was measured by QCT (General Electric LightSpeed Pro scanner, General Electric Healthcare, Waukesha, WI, USA). Scans were performed with helical acquisition at settings of 120?kV and 100?mA, with 2.5?mm slice thickness through L1 and L2 vertebrae. 3D reconstructive analysis was performed using QCT PRO software version 4.2 (Mindways Software, Inc., Austin, TX, USA). Coverage of the area of interest by fat bags was confirmed by anterior�Cposterior and lateral scout scans. The density of trabecular bone was determined BKM120 by means of comparison with an internal aqueous K2HPO4 standard, and the values obtained for the vertebrae were then averaged. The precision for this technique is 1.5%,11, 12, 14 corresponding to an LSC of 4.2%. For Y-27632 molecular weight analyses involving the anthropomorphic phantom, linear regression was used to compare change in BMD after sequential fat layering at each of the three vertebral density levels. For the human studies, pair-wise t tests were used to evaluate differences in BMD before and after fat layering. Correlation coefficients were calculated for BMD, and Bland-Altman plots were used to compare measurement errors before and after fat layering. The effect of fat layering on the precision of DXA and QCT was determined by calculating the root-mean-square coefficient of variation (RMS CV%) of the change in BMD between the baseline and simulated fat scans.15 All statistical analyses were performed using SAS 9.2 (SAS software Inc., Cary, NC, USA). Data are reported as mean?��?standard deviation (SD). DXA BMD increased linearly with successive fat layers for phantom vertebral densities in the normal (r2?=?0.64, p?<?0.01) and osteopenic range (r2?=?0.55, p?<?0.01), but at the osteoporotic level there were erratic and bidirectional changes in BMD that did not fit a linear trend.</div>
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