目的:研究正常胎儿大脑后动脉(posterior cerebral artery,PCA)两个解剖节段的血流参数随孕周变化规律。方法:用多普勒检测132例正常单胎胎儿PCA两个解剖节段,PCA由基底动脉发出至后交通动脉之前节段(the first segment of posterior ce...目的:研究正常胎儿大脑后动脉(posterior cerebral artery,PCA)两个解剖节段的血流参数随孕周变化规律。方法:用多普勒检测132例正常单胎胎儿PCA两个解剖节段,PCA由基底动脉发出至后交通动脉之前节段(the first segment of posterior cerebral artery,PCAS1)和PCA与后交通动脉汇合之后节段(the second segment of posterior cerebral artery,PCAS2)的速度参数[收缩期峰值流速(peak systolic velocity,PSV)、舒张末期流速(end diastolic velocity,EDV)、时间-平均最大速度(time-average maximum velocity,TAMAXV)、速度时间积分(velocity time integral,VTI)]以及阻力参数[收缩期峰值流速与舒张末期流速比值(systolic peak velocity and end diastolic velocity ratio,S/D)、搏动指数(pulsatility index,PI)、阻力指数(resistance index,RI)]。将PCAS1和PCAS2血流参数分别与孕周行Pearson相关分析及多种曲线拟合,并对比分析两节段间的血流参数差异。结果:PCAS1和PCAS2速度参数随孕周增长而增加(P<0.0001),速度参数与孕周均以Quadratic曲线拟合度最高(P<0.0001)。PCAS1和PCAS2阻力参数与孕周无明显相关性(P>0.05)。PCAS1阻力明显高于PCAS2(P<0.05)。结论:正常胎儿PCA两个节段速度参数均与孕周存在正相关关系,阻力参数与孕周不存在相关关系,两节段存在阻力差异。对正常胎儿PCA血流参数的研究可完善胎儿脑循环的评估,为高危妊娠的监测提供有力的根据及补充。展开更多
The original nonlinear chirp scaling(NCS) algorithm was extended for high precision processing of the highly squinted curvilinear trajectory synthetic aperture radar(CTSAR).Based on the analysis of slant range model a...The original nonlinear chirp scaling(NCS) algorithm was extended for high precision processing of the highly squinted curvilinear trajectory synthetic aperture radar(CTSAR).Based on the analysis of slant range model and the frequency spectrum characteristics of the echo signal,a novel nonlinear chirp scaling function and more complex phase compensation factors with both velocity and acceleration parameters were proposed in the new algorithm for accommodation to curvilinear trajectory.The processing flow and computational complexity of modified NCS algorithm were fundamentally the same as the original NCS algorithm.However,the higher order phase compensation,range cell migration correction(RCMC) and range-variant secondary range compression(SRC) caused by the non-linear aperture and the severe range-azimuth coupling were accomplished accurately and efficiently without interpolation.Simulation results show that data acquired with a curvilinear aperture and a squint angle up to about 50° for X-band can be processed with no evident degradation of impulse response function.展开更多
文摘目的:研究正常胎儿大脑后动脉(posterior cerebral artery,PCA)两个解剖节段的血流参数随孕周变化规律。方法:用多普勒检测132例正常单胎胎儿PCA两个解剖节段,PCA由基底动脉发出至后交通动脉之前节段(the first segment of posterior cerebral artery,PCAS1)和PCA与后交通动脉汇合之后节段(the second segment of posterior cerebral artery,PCAS2)的速度参数[收缩期峰值流速(peak systolic velocity,PSV)、舒张末期流速(end diastolic velocity,EDV)、时间-平均最大速度(time-average maximum velocity,TAMAXV)、速度时间积分(velocity time integral,VTI)]以及阻力参数[收缩期峰值流速与舒张末期流速比值(systolic peak velocity and end diastolic velocity ratio,S/D)、搏动指数(pulsatility index,PI)、阻力指数(resistance index,RI)]。将PCAS1和PCAS2血流参数分别与孕周行Pearson相关分析及多种曲线拟合,并对比分析两节段间的血流参数差异。结果:PCAS1和PCAS2速度参数随孕周增长而增加(P<0.0001),速度参数与孕周均以Quadratic曲线拟合度最高(P<0.0001)。PCAS1和PCAS2阻力参数与孕周无明显相关性(P>0.05)。PCAS1阻力明显高于PCAS2(P<0.05)。结论:正常胎儿PCA两个节段速度参数均与孕周存在正相关关系,阻力参数与孕周不存在相关关系,两节段存在阻力差异。对正常胎儿PCA血流参数的研究可完善胎儿脑循环的评估,为高危妊娠的监测提供有力的根据及补充。
基金Project(61171133) supported by the National Natural Science Foundation of ChinaProject(61101182) supported by the National Natural Science Foundation for Young Scientists of ChinaProject(11JJ1010) supported by the Natural Science Foundation for Distinguished Young Scholars of Hunan Province,China
文摘The original nonlinear chirp scaling(NCS) algorithm was extended for high precision processing of the highly squinted curvilinear trajectory synthetic aperture radar(CTSAR).Based on the analysis of slant range model and the frequency spectrum characteristics of the echo signal,a novel nonlinear chirp scaling function and more complex phase compensation factors with both velocity and acceleration parameters were proposed in the new algorithm for accommodation to curvilinear trajectory.The processing flow and computational complexity of modified NCS algorithm were fundamentally the same as the original NCS algorithm.However,the higher order phase compensation,range cell migration correction(RCMC) and range-variant secondary range compression(SRC) caused by the non-linear aperture and the severe range-azimuth coupling were accomplished accurately and efficiently without interpolation.Simulation results show that data acquired with a curvilinear aperture and a squint angle up to about 50° for X-band can be processed with no evident degradation of impulse response function.
