心电图门控和周围门控技术相位对比脉冲序列扫描的对比分析

Analysis of phase-contrast pulse sequence scanning with ECG trigger and PPU trigger

目的探讨采用不同门控技术对相位对比脉冲序列扫描的影响。方法应用飞利浦公司产GyroscanNT1.5T磁共振成像仪,对21例正常健康志愿者的左肺动脉进行流动补偿相位对比脉冲序列扫描。其中15例采用心电图(ECG)门控技术,6例采用周围(PPU)门控技术。结果两种扫描方式均可重建出3种图像,即快速梯度回波解剖图(FFE/M)、相位模数图(PCA/M)和相位速度图(PCA/P),并由相位速度图获得左肺动脉的时间-速度模式图。采用PPU门控技术扫描测得左肺动脉的最大血流速度为80.6cm/s±17.3cm/s,左肺动脉平均速度为45.4cm/s±7.2cm/s;采用ECG门控技术获得的左肺动脉最大血流速度为82.0cm/s±12.8cm/s,平均速度为46.0cm/s±6.0cm/s。两者间无统计学差异。结论采用相位对比脉冲序列,加心电图门控方式获得的图像与心脏的心动周期相一致,而加周围门控方式获得图像的时相与前者相比有一段时间的延迟,但获得的左肺动脉血流速度最大值和平均值没有显著差别。

Objective To investigate the different effects of phase-contras t pulse sequence scanning with different cardiac trigger. Methods Twenty one heal thy volunteers underwent MRI scanning with flow compensation phase contrast pul se sequence at a Philips Gyroscan NT 1.5 T MR scanner.Among them,cardiac synchro nization was used with ECG trigger in 15 healthy volunteers and with PPU trigger in 6 healthy volunteers.Results FFE/M,PCA/M and PCA/P images were reconstructed ,and the time velocity profile was obtained by analysis of PCA/P image.The max imum blood flow velocity and mean velocity of left pulmonary artery(LPA)with PPU were 80.6±17.3(cm/s)and 45.4±7.2(cm/s);and with ECG they were 82.0±12.8(cm/s )and 46.0±6.0(cm/s)respectively.Conclusion Images obtained by phase contrast p ulse sequence scanning with ECG trigger are matched with heart cycles,however,im ages obtained by phase contrast pulse sequence scanning with PPU trigger are no t matched with heart cycles,there is a delay between them.