目的 探讨编码速率(Venc)对 基底动脉(BA)相位对比磁共振成像(PC MRI)测量结果的影响。方法 对36例健康 成年志愿者行BA PCMRI测量，选用TOFMRI垂直BA中间段定位扫描，在PCA/M幅 度像上沿边缘绘制感兴趣区。每例预置 Venc 40、80、120、160、200 cm/s行5 次扫描。取峰值流速(PV)、平均流速(MV) 及平均流量(MF)进行分析。结果 Venc预 置40cm/s均出现相位混淆现象。Venc预 置80-160cm/s各指标均数间无统计学差 异(FPV=0.46，FMV=0.07，F MF=0.17； P值均>0.05)；Venc预置40-160cm/s 、 Venc80-200cm/s各指标均数间存在差异 (FPV=37.22，FMV=57.92，FMV=34.72； FPV=11.81，FMV=7.23，FMF=9.01；P值均 <0.01)。结论 BA PCMRI测量可行Venc区 间为80-160cm/s。

Objective To evaluate the normal flow velocity measurements of Basilar Artery (BA) utilizing phase contrast magnetic resonance imaging(PCMRI), and explore the influences of different Velocity encoding(Venc) on the PCMR flow measurements of BA. Methods 36 healthy volunteers were recruited for research. For every volunteer, the localizer was placed perpendicular to ampulla region of the BA on TOF-MRA image with the Venc of 40, 80, 120, 160, 200 cm/s. The region of interest was drew in the PCA/M amplitude image when the BA could be seen optimally. The evaluated parameters were the peak velocity (PV), mean velocity (MV), and the mean flow (MF). Using SPSS17.0 statistical analysis, P<0.05 was considered statistically significant. Results When Venc was set 40cm/s, all phase images appeared phase confusion. When Venc was set 80~200cm/s, all parameters did not show any statistical difference(FPV=0.46, FMV=0.07, FMF=0.17, P>0.05). When Venc was set 40~200cm/s and 80~200cm/ s, all parameters showed prominent statistical difference(FPV =37.22, FMV=57.92, FMV=34.72, FPV=11.81, FMV=7.23, FMF=9.01, P<0.01). Conclusion The feasible Venc district was 80~160cm/s.