心率波动对16层CT冠脉成像图像质量的影响及对策(心脏体模模拟实验)

目的 研究心率波动对16层螺旋CT冠状动脉成像质量的影响及心率波动情况下最佳扫描条件.方法 采用GE Light-Speed 16层螺旋CT,以心脏冠脉扫描模式对心脏体模进行扫描.心率设置为以60次/min、85次/min为中心上下波动2组,每组分别设置波幅为2.5次/min、5次/min和10次/min各3小组,分别对6组心率波动情况下的心脏体模以心脏冠脉扫描模式进行扫描,所有扫描数据在R-R间期5%、15%、25%、35%、45%、55%、65%、75%、85%、95%相位分别进行单扇区(Segment)、双扇区(Burst-2)和四扇区重建(Burst-4).重建数据传至AW4.1工作站后处理成像.后处理方法采用容积再现(VR)、多平面重组(MPR)模式.由1名高年资医师和1名技师分别对不同重组图像进行评分.统计学处理采用析因分析.结果 (1)方差分析显示,总模型具有显著意义(F=22.58,P《0.0001),各变量(心率、波幅、算法和相位)具有显著意义,均对冠状动脉成像质量有影响;(2)不同心率之间比较心率为60次/min者图像质量评分均数显著高于心率为85次/min者(P《0.05);(3)不同波动范围之间比较波幅为2.5次/min和5次/min者,图像质量评分均数高于波幅为10次/min者(P《0.05),但波幅为2.5次/min和5次/min无显著差异(P》0.05);(4)不同重建算法之间比较算法为Burst-4和Burst-2者图像质量评分均数显著高于算法为Segment(P《0.05),但Burst-4和Burst-2之间无显著差异(P》0.05);(5)不同相位之间比较相位为45%,95%显著高于其他相位(P《0.05),但上述二者相位之间无显著差异(P》0.05).相位为15%者,图像质量最差.结论 新型心脏动态体模评价心率波动对16层螺旋CT冠状动脉成像质量的影响及心率波动情况下最佳扫描条件分析,能够为临床应用和基础研究提供帮助.

Influence of Fluctuation of Heart Rate on Image Quality of 16-slice Spiral CT Coronary Angiography and Optimization of Scanning Parameters:Cardiac Phantom Study

Objective To study the influence of fluctuation of heart rate on image quality of 16-slice spiral CT coronary angiography and optimization of scanning parameters.Methods An adjustable pulsating cardiac phantom containing predetermined simulated coronary arteries was scanned using a 16-slice spiral CT(GE LightSpeed 16)with cardiac pulsating rates at 60 and 85 beats per minute(bpm)and fluctuation amplitude as 2.5,5 and 10 bpm respectively.The raw data were reconstructed using one-sector(Snapshot segment),two-sector(burst-2)and four-sector(burst-4)reconstruction algorithm at 5%~95% of the R-R interval with an increment of 10%.Reconstruction images were transmitted to workstation(ADW4.1)and post-processed using a pattern of volume rendering(VR)and multi-planar reformation(MPR).According to the same evaluation standard of reformatted image,the image quality was scored by a radiologist and a technician.The correlation between heart rate(HR),fluctuation amplitude of HR,reconstruction algorithm,phase(R-R interval)and the score of image quality were analyzed.Results ANOVA suggests that all variables including HR,fluctuation amplitude of HR,reconstruction algorithm,phase(R-R interval)had significant influence on the image quality score.The average score in the 60 bpm groups was much higher than that in the 85 bpm groups(P<0.05).The average score in the groups(fluctuation amplitude of 2.5 bpm and 5 bpm)was higher than that in the groups(fluctuation amplitude of 10 bpm)(P< 0.05),while there was no significant difference between the former two groups(P>0.05).The average score of the two-sector and four-sector reconstruction algorithm groups was significantly higher than that in the one-sector reconstruction alg-orithm groups(P<0.05),while there was no significant difference between the former two groups(P>0.05).The average scores in the groups with phase at 45% and 95% R-R interval were significantly higher than that in other groups(P<0.05),while there was no significant difference between the former two groups(P>0.05).The image quality in the groups with phase at 15% R-R interval was the worst.Conclusion The Influence of fluctuation of heart rate on image quality of spiral CT coronary angiography and optimization of scanning parameters can be evaluated with 16-slice spiral CT using a pulsating cardiac phantom.It plays an important role in clinical research and application.