目的探讨高分辨磁共振血管壁成像(high-resolution magnetic resonance vessel wall imaging,HRMR-VWI)在椎-基底动脉病变诊断中的应用价值。方法对52例经CTA/MRA/DSA确诊椎-基底动脉管腔病变的患者,行HRMR-VWI T 1-VISTA序列平扫加增...目的探讨高分辨磁共振血管壁成像(high-resolution magnetic resonance vessel wall imaging,HRMR-VWI)在椎-基底动脉病变诊断中的应用价值。方法对52例经CTA/MRA/DSA确诊椎-基底动脉管腔病变的患者,行HRMR-VWI T 1-VISTA序列平扫加增强检查,评估病变段血管壁改变及病因探究。结果52例椎-基底动脉管腔病变患者中,发现24例动脉粥样硬化改变,占46.2%,均表现为偏心性管壁增厚,增强扫描管壁轻度或明显强化;9例原发性中枢神经系统血管炎,占17.3%,表现为管壁向心性增厚,明显强化;12例椎基底动脉夹层,占23.1%,可见内膜瓣,双腔征,夹层开口位置;7例动脉瘤,占13.4%,5例发生于椎动脉,2例发生于基底动脉,HRMR-VWI清晰可见瘤壁厚度及强化特点。结论HRMR-VWI能够为椎-基底动脉病变病因探究、治疗方案制定提供重要信息,是椎-基底动脉病变的重要检查方法。展开更多
BACKGROUND Automated,accurate,objective,and quantitative medical image segmentation has remained a challenging goal in computer science since its inception.This study applies the technique of convolutional neural netw...BACKGROUND Automated,accurate,objective,and quantitative medical image segmentation has remained a challenging goal in computer science since its inception.This study applies the technique of convolutional neural networks(CNNs)to the task of segmenting carotid arteries to aid in the assessment of pathology.AIM To investigate CNN’s utility as an ancillary tool for researchers who require accurate segmentation of carotid vessels.METHODS An expert reader delineated vessel wall boundaries on 4422 axial T2-weighted magnetic resonance images of bilateral carotid arteries from 189 subjects with clinically evident atherosclerotic disease.A portion of this dataset was used to train two CNNs(one to segment the vessel lumen and the other to segment the vessel wall)with the remaining portion used to test the algorithm’s efficacy by comparing CNN segmented images with those of an expert reader.Overall quantitative assessment between automated and manual segmentations was determined by computing the DICE coefficient for each pair of segmented images in the test dataset for each CNN applied.The average DICE coefficient for the test dataset(CNN segmentations compared to expert’s segmentations)was 0.96 for the lumen and 0.87 for the vessel wall.Pearson correlation values and the intra-class correlation coefficient(ICC)were computed for the lumen(Pearson=0.98,ICC=0.98)and vessel wall(Pearson=0.88,ICC=0.86)segmentations.Bland-Altman plots of area measurements for the CNN and expert readers indicate good agreement with a mean bias of 1%-8%.CONCLUSION Although the technique produces reasonable results that are on par with expert human assessments,our application requires human supervision and monitoring to ensure consistent results.We intend to deploy this algorithm as part of a software platform to lessen researchers’workload to more quickly obtain reliable results.展开更多
In this paper,blood flow in artery was treated as the flow under equilibrium state (the steady flow under mean pressure) combined with the periodically small sulsatile flow.Based on vascular zero stress state ,t...In this paper,blood flow in artery was treated as the flow under equilibrium state (the steady flow under mean pressure) combined with the periodically small sulsatile flow.Based on vascular zero stress state ,the pulsatile strains according to the radial and axial displacements of blood vessel were obtained.With the use of Hooke's law,the pulsatile strains and the corresponding Cauchy stresses were connected,so the corresponding wall motion equations could be established here.By solving the linearized Navier Stokes equations,the analytic expressions of the blood flow velocities and the vascular displacements could be obtained,and the in fluence of the circumferential and axial stretch ratio on pulsatile blood flow and vascular motion was discussed in details.展开更多
A problem of couple motion between vessel wall and blood in the entrance regionof a tapered vessel is considered in this paper A mathematical model of co-coupleaction is formed for both motion of vessel wall and blood...A problem of couple motion between vessel wall and blood in the entrance regionof a tapered vessel is considered in this paper A mathematical model of co-coupleaction is formed for both motion of vessel wall and blood flow in the entrance regance regionof elastic vessel with tapered angle. Under the situation that the relative boundary conditions are satisfied a.set of velocity distribution formula. pressure distributionformula for the blood flow in a tapered elastic vessel are derived. Some importantconclusions are obtained.展开更多
文摘目的探讨高分辨磁共振血管壁成像(high-resolution magnetic resonance vessel wall imaging,HRMR-VWI)在椎-基底动脉病变诊断中的应用价值。方法对52例经CTA/MRA/DSA确诊椎-基底动脉管腔病变的患者,行HRMR-VWI T 1-VISTA序列平扫加增强检查,评估病变段血管壁改变及病因探究。结果52例椎-基底动脉管腔病变患者中,发现24例动脉粥样硬化改变,占46.2%,均表现为偏心性管壁增厚,增强扫描管壁轻度或明显强化;9例原发性中枢神经系统血管炎,占17.3%,表现为管壁向心性增厚,明显强化;12例椎基底动脉夹层,占23.1%,可见内膜瓣,双腔征,夹层开口位置;7例动脉瘤,占13.4%,5例发生于椎动脉,2例发生于基底动脉,HRMR-VWI清晰可见瘤壁厚度及强化特点。结论HRMR-VWI能够为椎-基底动脉病变病因探究、治疗方案制定提供重要信息,是椎-基底动脉病变的重要检查方法。
基金Supported by American Heart Association Grant in Aid Founders Affiliate No.17GRNT33420119(Mani V)NIH NHLBI 2R01HL070121(Fayad ZA)and NIH NHLBI 1R01HL135878(Fayad ZA)
文摘BACKGROUND Automated,accurate,objective,and quantitative medical image segmentation has remained a challenging goal in computer science since its inception.This study applies the technique of convolutional neural networks(CNNs)to the task of segmenting carotid arteries to aid in the assessment of pathology.AIM To investigate CNN’s utility as an ancillary tool for researchers who require accurate segmentation of carotid vessels.METHODS An expert reader delineated vessel wall boundaries on 4422 axial T2-weighted magnetic resonance images of bilateral carotid arteries from 189 subjects with clinically evident atherosclerotic disease.A portion of this dataset was used to train two CNNs(one to segment the vessel lumen and the other to segment the vessel wall)with the remaining portion used to test the algorithm’s efficacy by comparing CNN segmented images with those of an expert reader.Overall quantitative assessment between automated and manual segmentations was determined by computing the DICE coefficient for each pair of segmented images in the test dataset for each CNN applied.The average DICE coefficient for the test dataset(CNN segmentations compared to expert’s segmentations)was 0.96 for the lumen and 0.87 for the vessel wall.Pearson correlation values and the intra-class correlation coefficient(ICC)were computed for the lumen(Pearson=0.98,ICC=0.98)and vessel wall(Pearson=0.88,ICC=0.86)segmentations.Bland-Altman plots of area measurements for the CNN and expert readers indicate good agreement with a mean bias of 1%-8%.CONCLUSION Although the technique produces reasonable results that are on par with expert human assessments,our application requires human supervision and monitoring to ensure consistent results.We intend to deploy this algorithm as part of a software platform to lessen researchers’workload to more quickly obtain reliable results.
文摘In this paper,blood flow in artery was treated as the flow under equilibrium state (the steady flow under mean pressure) combined with the periodically small sulsatile flow.Based on vascular zero stress state ,the pulsatile strains according to the radial and axial displacements of blood vessel were obtained.With the use of Hooke's law,the pulsatile strains and the corresponding Cauchy stresses were connected,so the corresponding wall motion equations could be established here.By solving the linearized Navier Stokes equations,the analytic expressions of the blood flow velocities and the vascular displacements could be obtained,and the in fluence of the circumferential and axial stretch ratio on pulsatile blood flow and vascular motion was discussed in details.
文摘A problem of couple motion between vessel wall and blood in the entrance regionof a tapered vessel is considered in this paper A mathematical model of co-coupleaction is formed for both motion of vessel wall and blood flow in the entrance regance regionof elastic vessel with tapered angle. Under the situation that the relative boundary conditions are satisfied a.set of velocity distribution formula. pressure distributionformula for the blood flow in a tapered elastic vessel are derived. Some importantconclusions are obtained.
