目的对比分析磁共振3D BRAVO序列与TRICKS序列对脑静脉血栓检出的优劣,探讨脑静脉血栓的MR检查方法.方法回顾性分析云南省第二人民医院2011年1月至2014年6月临床确诊脑静脉血栓的40例,所有患者均先行TRICKS序列扫描,结束后再进行3D BRAV...目的对比分析磁共振3D BRAVO序列与TRICKS序列对脑静脉血栓检出的优劣,探讨脑静脉血栓的MR检查方法.方法回顾性分析云南省第二人民医院2011年1月至2014年6月临床确诊脑静脉血栓的40例,所有患者均先行TRICKS序列扫描,结束后再进行3D BRAVO序列扫描,扫描结果分为静脉窦、深静脉及浅静脉组3组进行对比分析,分别评价2种序列对静脉血栓的检出率并对结果进行统计分析.结果 3D BRAVO及TRICKS序列对静脉窦组血栓的检出率分别为48例(98.0%)及49例(100%),深静脉组血栓检出率13例(92.9%)及14例(100%),2组中两种方法无明显统计学差异(P>0.05),浅静脉组血栓检出率12例(66.7%)及18例(100%),2种方法有明显差异(P<0.05).结论 3D BRAVO序列可以精确显示血栓的静脉部位、累及范围,尤其对浅静脉组的血栓显示更具优势,具有较好临床应用价值,结合TRICKS序列3D重建显示更为直观.展开更多
目的探讨时间分辨对比剂动态显像技术(TRICKS)对于脑动静脉畸形的诊断价值。方法收集笔者所在医院25例脑动脉畸形(AVM)患者资料,使用GE公司超导Signa HD 1.5T MR扫描仪,应用椭圆中心TRICKS,对病灶区进行连续不间断扫描,利用多平面重建...目的探讨时间分辨对比剂动态显像技术(TRICKS)对于脑动静脉畸形的诊断价值。方法收集笔者所在医院25例脑动脉畸形(AVM)患者资料,使用GE公司超导Signa HD 1.5T MR扫描仪,应用椭圆中心TRICKS,对病灶区进行连续不间断扫描,利用多平面重建及最大强度投影技术对原始图像进行血管重建。结果 TRICKS清楚显示大小不等的畸形血管巢及供血动脉和引流静脉。畸形血管巢位于颞叶7例,顶叶6例,额叶5例、枕叶6例和小脑半球1例。发现供血动脉37支,其中单支供血动脉15例,多支供血动脉10例;引流静脉33支,单只引流10例,多支引流15例。结论 TRICKS显示AVM的供血动脉、畸形血管巢和引流静脉,为临床治疗方案的制定提供可靠的依据,值得在临床上推广使用。展开更多
Large-eddy simulation(LES) with fully resolved rotor method(FRM) is applied to explore the turbulent wake flow characteristics and vortex evolution laws of a two-bladed horizontal-axis wind turbine. Relevant wind tunn...Large-eddy simulation(LES) with fully resolved rotor method(FRM) is applied to explore the turbulent wake flow characteristics and vortex evolution laws of a two-bladed horizontal-axis wind turbine. Relevant wind tunnel experiments have been done based on time resolved particle image velocimetry(TRPIV) technique. The simulation results are validated by the experimental data and they are in good agreement. The axial average velocity, turbulent kinetic energy, shear Reynolds stress, and vortex structure of the wind turbine wake are analyzed based on the comparison of LES results and experimental data. It is observed that the wake diameter of wind turbine enlarges with the increase of tip speed ratio(TSR). Turbulent kinetic energy meets its minimum value when x/R=2.0. Shear Reynolds stress appears a positive peak in the near wake when x/R<2.0, and the value of shear Reynolds stress decreases along the axial direction. The blade tip vortex dissipates more quickly than the central vortex in the wind turbine wake, and the gradient of the relationship curve between the blade tip vortex core position and the vortex age decreases as the TSR increases. With the increase of TSR, the thrust coefficient increases, and the power coefficient increases first and then decreases.The present work proves that LES with FRM could calculate wind turbine turbulent wake flow with a high accuracy.展开更多
文摘目的对比分析磁共振3D BRAVO序列与TRICKS序列对脑静脉血栓检出的优劣,探讨脑静脉血栓的MR检查方法.方法回顾性分析云南省第二人民医院2011年1月至2014年6月临床确诊脑静脉血栓的40例,所有患者均先行TRICKS序列扫描,结束后再进行3D BRAVO序列扫描,扫描结果分为静脉窦、深静脉及浅静脉组3组进行对比分析,分别评价2种序列对静脉血栓的检出率并对结果进行统计分析.结果 3D BRAVO及TRICKS序列对静脉窦组血栓的检出率分别为48例(98.0%)及49例(100%),深静脉组血栓检出率13例(92.9%)及14例(100%),2组中两种方法无明显统计学差异(P>0.05),浅静脉组血栓检出率12例(66.7%)及18例(100%),2种方法有明显差异(P<0.05).结论 3D BRAVO序列可以精确显示血栓的静脉部位、累及范围,尤其对浅静脉组的血栓显示更具优势,具有较好临床应用价值,结合TRICKS序列3D重建显示更为直观.
基金supported by the Foundation of Key Laboratory for Wind and Solar Power Energy Utilization Technology,Ministry of Education and Inner Mongolia Construction(Grant No.201503)the National Natural Science Foundation of China(Grant No.51346006)
文摘Large-eddy simulation(LES) with fully resolved rotor method(FRM) is applied to explore the turbulent wake flow characteristics and vortex evolution laws of a two-bladed horizontal-axis wind turbine. Relevant wind tunnel experiments have been done based on time resolved particle image velocimetry(TRPIV) technique. The simulation results are validated by the experimental data and they are in good agreement. The axial average velocity, turbulent kinetic energy, shear Reynolds stress, and vortex structure of the wind turbine wake are analyzed based on the comparison of LES results and experimental data. It is observed that the wake diameter of wind turbine enlarges with the increase of tip speed ratio(TSR). Turbulent kinetic energy meets its minimum value when x/R=2.0. Shear Reynolds stress appears a positive peak in the near wake when x/R<2.0, and the value of shear Reynolds stress decreases along the axial direction. The blade tip vortex dissipates more quickly than the central vortex in the wind turbine wake, and the gradient of the relationship curve between the blade tip vortex core position and the vortex age decreases as the TSR increases. With the increase of TSR, the thrust coefficient increases, and the power coefficient increases first and then decreases.The present work proves that LES with FRM could calculate wind turbine turbulent wake flow with a high accuracy.
