AIM： To report our experience with computed tomography colonography （CTC） systematically performed in subjects with positive faecal occult blood test （FOBT） and an incomplete colonoscopy in the setting of a popul...AIM： To report our experience with computed tomography colonography （CTC） systematically performed in subjects with positive faecal occult blood test （FOBT） and an incomplete colonoscopy in the setting of a population-based screening for colorectal cancer （CRC）. METHODS： From April 2006 to April 2007, 43 290 individuals （age range 50-70） who adhered to the regional screening program for the prevention of CRC underwent immunochemical FOBT. FOBT was positive in 1882 subjects （4.3%）. 1463 （77.7%） of these subjects underwent colonoscopy, 903 performed in a single center. Of 903 colonoscopies 65 （7.2%） were incomplete. Forty-two of these subjects underwent CTC. CTC was performed with a 16-MDCT scanner after standard bowel prep （polyethyleneglycole） in both supine and prone position. Subjects whose CTC showed polyps or masses were referred to the endoscopist for repeat colonoscopy under sedation or underwent surgery. Perlesion and per-segment positive predictive values （PPV） were calculated. RESULTS： Twenty-one （50%） of 42 CTCs showed polyps or masses. Fifty-five of these subjects underwent a repeat colonoscopy, whereas 2 subjects underwent surgery for colonic masses of indeterminate nature. Four subjects refused further examinations. CTC correctly identified 2 colonic masses and 20 polyps. PPV for masses or polyps greater than 9 mm was of 87.5%. Per-lesion and per-segment PPV were, respectively, 83.3% and 83.3% for polyps greater or equal to 10 mm, and 77.8% and 85.7% for polyps of 6-9 mm. CONCLUSION： In the context of a screening program for CRC based on FOBT, CTC shows high per-segment and per-lesion PPV for colonic masses and polyps greater than 9 mm. Therefore, CTC has the potential to become a useful technique for evaluation of the non visualized part of the colon after incomplete colonoscopy.展开更多
Deformation and failure of deep clay samples are closely related to energy changes.Investigating the energy conversion and damage behavior of deep clay during loading and unloading tests has important significance for...Deformation and failure of deep clay samples are closely related to energy changes.Investigating the energy conversion and damage behavior of deep clay during loading and unloading tests has important significance for prevention-control of soil destabilization damage caused by mine shaft excavation.In the present work,triaxial tests of consolidated clay under different stress paths and stress rates were conducted.The results reveal that the mechanical properties of soils have strong stress rate effects and the samples mainly experience energy storage in the elastic stage,after that,the energy conversion mainly undergoes an increase of dissipative energy and release of elastic energy,which is also confirmed by the results of the analysis in the subsequent CT tests.Two damage indicators were compared,finding that the indicator based on dissipative energy has more obvious differences in two stress paths and can be used as a better indicator to describe the damage evolution of soils.Finally,in the triaxial shear test,due to the unloading effect of confining pressure,the damage of soils increased more rapidly near breaking than in the triaxial compression test,which indicates that the damage caused by unloading on deep soil is more abrupt than that caused by loading.展开更多
DSA images show vessels with clarity and CT images show bones distinctly. In this paper, we present an experimental research on the frameless registration of DSA/CT images based on localization algorithm. With four ex...DSA images show vessels with clarity and CT images show bones distinctly. In this paper, we present an experimental research on the frameless registration of DSA/CT images based on localization algorithm. With four external markers, the vessels and bones in human brain can be integrated. The mean accuracy of simulated experiment is about 2.0 mm. The experiment proved that the 3D images composed cerebral anatomy and vasculature could help neurosurgeons perform accurate diagnosis and make right operation planning.展开更多
文摘AIM： To report our experience with computed tomography colonography （CTC） systematically performed in subjects with positive faecal occult blood test （FOBT） and an incomplete colonoscopy in the setting of a population-based screening for colorectal cancer （CRC）. METHODS： From April 2006 to April 2007, 43 290 individuals （age range 50-70） who adhered to the regional screening program for the prevention of CRC underwent immunochemical FOBT. FOBT was positive in 1882 subjects （4.3%）. 1463 （77.7%） of these subjects underwent colonoscopy, 903 performed in a single center. Of 903 colonoscopies 65 （7.2%） were incomplete. Forty-two of these subjects underwent CTC. CTC was performed with a 16-MDCT scanner after standard bowel prep （polyethyleneglycole） in both supine and prone position. Subjects whose CTC showed polyps or masses were referred to the endoscopist for repeat colonoscopy under sedation or underwent surgery. Perlesion and per-segment positive predictive values （PPV） were calculated. RESULTS： Twenty-one （50%） of 42 CTCs showed polyps or masses. Fifty-five of these subjects underwent a repeat colonoscopy, whereas 2 subjects underwent surgery for colonic masses of indeterminate nature. Four subjects refused further examinations. CTC correctly identified 2 colonic masses and 20 polyps. PPV for masses or polyps greater than 9 mm was of 87.5%. Per-lesion and per-segment PPV were, respectively, 83.3% and 83.3% for polyps greater or equal to 10 mm, and 77.8% and 85.7% for polyps of 6-9 mm. CONCLUSION： In the context of a screening program for CRC based on FOBT, CTC shows high per-segment and per-lesion PPV for colonic masses and polyps greater than 9 mm. Therefore, CTC has the potential to become a useful technique for evaluation of the non visualized part of the colon after incomplete colonoscopy.
基金Project(2016YFC0600904)supported by the National Key Research and Development Program of ChinaProject(BK20200653)supported by the Natural Science Foundation of Jiangsu,ChinaProject(2020M681768)supported by the China Postdoctoral Science Foundation。
文摘Deformation and failure of deep clay samples are closely related to energy changes.Investigating the energy conversion and damage behavior of deep clay during loading and unloading tests has important significance for prevention-control of soil destabilization damage caused by mine shaft excavation.In the present work,triaxial tests of consolidated clay under different stress paths and stress rates were conducted.The results reveal that the mechanical properties of soils have strong stress rate effects and the samples mainly experience energy storage in the elastic stage,after that,the energy conversion mainly undergoes an increase of dissipative energy and release of elastic energy,which is also confirmed by the results of the analysis in the subsequent CT tests.Two damage indicators were compared,finding that the indicator based on dissipative energy has more obvious differences in two stress paths and can be used as a better indicator to describe the damage evolution of soils.Finally,in the triaxial shear test,due to the unloading effect of confining pressure,the damage of soils increased more rapidly near breaking than in the triaxial compression test,which indicates that the damage caused by unloading on deep soil is more abrupt than that caused by loading.
基金Supported by NSF(No.30570511) and National Fund for the Doctoral Program(No.200350)
文摘DSA images show vessels with clarity and CT images show bones distinctly. In this paper, we present an experimental research on the frameless registration of DSA/CT images based on localization algorithm. With four external markers, the vessels and bones in human brain can be integrated. The mean accuracy of simulated experiment is about 2.0 mm. The experiment proved that the 3D images composed cerebral anatomy and vasculature could help neurosurgeons perform accurate diagnosis and make right operation planning.
