A finite element solution for the Navier-Stokes equations for steady flow under the porosity effects through a double branched two-dimensional section of a three-dimensional model of a canine aorta was obtained. The n...A finite element solution for the Navier-Stokes equations for steady flow under the porosity effects through a double branched two-dimensional section of a three-dimensional model of a canine aorta was obtained. The numerical solution involves transforming a physical coordinates to a curvilinear boundary fitted coordinate system.The steady flow,branch flow and shear stress under the porous effects were discussed in detail. The shear stress at the wall was calculated for Reynolds number of 1 000 with branch to main aortic flow rate ratio as a parameter. The results are compared with earlier works involving experimental data and it has been observed that our results are very close to the exact solutions.This work is in fact an improvement of the work of Sharma et al. (2001) in the sense that computational technique is economic and (Reynolds) number is large.展开更多
Objective： To discuss the feasibility and clinical value of high-resolution magnetic resonance vessel wall imaging （HRMR VWI） for intracranial arterial stenosis. Date Sources： We retrieved information from PubMed ...Objective： To discuss the feasibility and clinical value of high-resolution magnetic resonance vessel wall imaging （HRMR VWI） for intracranial arterial stenosis. Date Sources： We retrieved information from PubMed database up to December 2015, using various search terms including vessel wall imaging （VWI）, high-resolution magnetic resonance imaging, intracranial arterial stenosis, black blood, and intracranial atherosclerosis. Study Selection： We reviewed peer-reviewed articles printed in English on imaging technique of VWI and characteristic findings of various intracranial vasculopathies on VWI. We organized this data to explain the value of VWI in clinical application. Results： VWI with black blood technique could provide high-quality images with submillimeter voxel size, and display both the vessel wall and lumen of intracranial artery simultaneously. Various intracranial vasculopathies （atherosclerotic or nonatherosclerotic） had differentiating features including pattern of wall thickening, enhancement, and vessel remodeling on VWI. This technique could be used for determining causes of stenosis, identification of stroke mechanism, risk-stratifying patients, and directing therapeutic management in clinical practice. In addition, a new morphological classification based on VWI could be established for predicting the efficacy of endovascular therapy. Conclusions： This review highlights the value of HRMR VWI for discrimination of different intracranial vasculopathies and directing therapeutic management.展开更多
目的:分析并探讨3D高分辨率磁共振血管壁成像技术对脑血管病变的评估价值,用以提升脑血管疾病检出率。方法:以2019年1月—12月在我院脑内科进行治疗的50例存在颅内动脉粥样硬化的脑血管病变患者作为研究组,另外选择50例同时期在我院进...目的:分析并探讨3D高分辨率磁共振血管壁成像技术对脑血管病变的评估价值,用以提升脑血管疾病检出率。方法:以2019年1月—12月在我院脑内科进行治疗的50例存在颅内动脉粥样硬化的脑血管病变患者作为研究组,另外选择50例同时期在我院进行体检的健康人员组成对照组,对所有人员实施3D高分辨率磁共振血管壁成像技术检测,对比两组动脉狭窄率、斑块面积、增强指数、LSA深度以及LSA数量等影像学特征,分析该技术在脑血管病变评估中的应用价值。结果:研究组受检人员增强指数为(0.89±0.22)%,明显高于对照组的(0.70±0.29)%(t=3.540,P=0.001);LSA深度为(16.72±1.51)mm,较之对照组的(20.78±4.69)mm则明显较低(t=5.589,P=0.000);两组狭窄率、斑块面积、L S A数量等指标则无明显差异(P>0.05)。结论:3D高分辨率磁共振血管壁成像技术对于颅内动脉粥样硬化的检出有关键意义,可以帮助医师准确判断患者病情,通过及时有效干预降低严重脑血管疾病发生概率,具有临床推广价值。展开更多
目的探讨7.0 T磁共振上三维血管壁成像技术(DANTE-FLASH)进行ApoE-/-小鼠颈动脉粥样硬化斑块成像的可行性。方法通过数值仿真优化成像参数,实现血管腔-壁对比度最大化。6只ApoE-/-小鼠和3只野生型小鼠在7.0 T MRI均行DANTEFLASH和流入...目的探讨7.0 T磁共振上三维血管壁成像技术(DANTE-FLASH)进行ApoE-/-小鼠颈动脉粥样硬化斑块成像的可行性。方法通过数值仿真优化成像参数,实现血管腔-壁对比度最大化。6只ApoE-/-小鼠和3只野生型小鼠在7.0 T MRI均行DANTEFLASH和流入流出饱和带的多层2D RARE(2D-IOSB-RARE)两种扫描。在管壁信噪比(SNRwall)、管腔信噪比(SNRlumen)、壁-腔对比噪声比(CNR)、管腔面积(LA)、和管壁面积(WA)方面分别对2D-IOSB-RARE和DANTE-FLASH序列进行比较。对于LA与WA,使用线性回归分析评估MR图像与病理图像测量结果的相关性。结果根据数值仿真结果,小鼠实验的DANTE模块采用了15°翻转角与150脉冲链。相较于2D-IOSB-RARE,DANTE-FLASH的CNR轻微降低(P<0.001),但层分辨率显著提高。组内相关系数(LA:ICC=0.94,P<0.001;WA:ICC=0.93,P<0.001)和Bland-Altman图显示出DANTE-FLASH和2DIOSB-RARE在评估LA和WA测量结果方面具有良好的一致性。MR图像与病理图像在定量测量LA(P<0.0001)和WA(P<0.0001)中呈现较强相关性。结论在7.0 T磁共振上,三维DANTE-FLASH黑血MR序列,可实现各向同性高空间分辨率成像,有利于ApoE-/-小鼠颈动脉粥样硬化病变的灵活显示和定量评估。展开更多
文摘A finite element solution for the Navier-Stokes equations for steady flow under the porosity effects through a double branched two-dimensional section of a three-dimensional model of a canine aorta was obtained. The numerical solution involves transforming a physical coordinates to a curvilinear boundary fitted coordinate system.The steady flow,branch flow and shear stress under the porous effects were discussed in detail. The shear stress at the wall was calculated for Reynolds number of 1 000 with branch to main aortic flow rate ratio as a parameter. The results are compared with earlier works involving experimental data and it has been observed that our results are very close to the exact solutions.This work is in fact an improvement of the work of Sharma et al. (2001) in the sense that computational technique is economic and (Reynolds) number is large.
文摘Objective： To discuss the feasibility and clinical value of high-resolution magnetic resonance vessel wall imaging （HRMR VWI） for intracranial arterial stenosis. Date Sources： We retrieved information from PubMed database up to December 2015, using various search terms including vessel wall imaging （VWI）, high-resolution magnetic resonance imaging, intracranial arterial stenosis, black blood, and intracranial atherosclerosis. Study Selection： We reviewed peer-reviewed articles printed in English on imaging technique of VWI and characteristic findings of various intracranial vasculopathies on VWI. We organized this data to explain the value of VWI in clinical application. Results： VWI with black blood technique could provide high-quality images with submillimeter voxel size, and display both the vessel wall and lumen of intracranial artery simultaneously. Various intracranial vasculopathies （atherosclerotic or nonatherosclerotic） had differentiating features including pattern of wall thickening, enhancement, and vessel remodeling on VWI. This technique could be used for determining causes of stenosis, identification of stroke mechanism, risk-stratifying patients, and directing therapeutic management in clinical practice. In addition, a new morphological classification based on VWI could be established for predicting the efficacy of endovascular therapy. Conclusions： This review highlights the value of HRMR VWI for discrimination of different intracranial vasculopathies and directing therapeutic management.
文摘目的:分析并探讨3D高分辨率磁共振血管壁成像技术对脑血管病变的评估价值,用以提升脑血管疾病检出率。方法:以2019年1月—12月在我院脑内科进行治疗的50例存在颅内动脉粥样硬化的脑血管病变患者作为研究组,另外选择50例同时期在我院进行体检的健康人员组成对照组,对所有人员实施3D高分辨率磁共振血管壁成像技术检测,对比两组动脉狭窄率、斑块面积、增强指数、LSA深度以及LSA数量等影像学特征,分析该技术在脑血管病变评估中的应用价值。结果:研究组受检人员增强指数为(0.89±0.22)%,明显高于对照组的(0.70±0.29)%(t=3.540,P=0.001);LSA深度为(16.72±1.51)mm,较之对照组的(20.78±4.69)mm则明显较低(t=5.589,P=0.000);两组狭窄率、斑块面积、L S A数量等指标则无明显差异(P>0.05)。结论:3D高分辨率磁共振血管壁成像技术对于颅内动脉粥样硬化的检出有关键意义,可以帮助医师准确判断患者病情,通过及时有效干预降低严重脑血管疾病发生概率,具有临床推广价值。
