中等心率下前瞻性心电门控冠状动脉成像的初步研究

THE INITIAL STUDY OF COMPUTED TOMOGRAPHIC CORONARY ANGIOGRAPHY WITH PROSPECTIVE ECG GATING AT INTE RMEDIATE HEART RATE

目的:采用前瞻性心电门控技术行中等心率病人冠状动脉CT成像,探讨其临床应用价值。方法:本研究回顾性分析76例病人[曝光心率(69.30±2.87)次/min(范围65次/min^75次/min)]影像资料,所有病人采用前门控技术成像,采集期相60%,padding time设置200 ms。对病人图像质量及辐射剂量进行统计描述。绘制ROC曲线推断不同心率下冠脉节段可评估性的切点。采用两独立样本秩和检验及χ2检验比较切点前后冠脉节段评分及可评估率差异;分析心率与冠脉评分的相关性。结果:共有972个冠状动脉节段参与评分,冠脉评分4.18±0.86分,可评估率为97.50%,辐射剂量6.37±2.13 m Sv;ROC曲线显示不同心率下冠脉节段可评估性的切点为70次/min,≤70次/min与>70次/min者冠脉节段评分比较:4.32 vs 3.94(Z=-6.701,P=0.00),差异具有统计学意义;≤70次/min与>70次/min者冠脉节段可评估率比较:0.8%vs 5.1%(χ2=17.210,P=0.00),差异具有统计学意义;pearson相关分析示R=-0.37,P=0.001,心率与图像质量呈负相关。结论:在中等心率下前瞻性心电门控技术可通过修改参数获得满足诊断的图像,推荐心率为62~70次/min时采用。

Objective：To evaluate the value of coronary artery computed tomographic angiography with prospectively gated axial（ PGA） CT technique at intermediate heart rate（65~75 beats per minute, bpm） using 64-slice spiral CT. Methods：This study was approved by institutional review board without informed consent. 76 patients with heart rates （ HR） 69. 30±2. 87 bpm （ range：65 ~75 bpm） was evaluated in this retrospective study. All patients used PGA CT technique（ tube voltage was 120 kV and tube current tailored to BMI ） . Image acquisition was performed at 60%of the RR interval, and the padding time setting was 200ms. The HR of ≤70 bpm and〉70 bpm was compared with image quality score and the percentage of assessable coronary artery segments by Mann-Whitney U-test and Chi-Square test. To evaluate the relationship between HR and image quality by pearson correlation analysis.Results：There were 972 coronary artery segments to be evaluated. Image quality score was 4. 18±0 . 86 . The percentage of assessable coronary artery segments was 97 . 50%, radiation dose was 6 . 37±2. 13 mSv. Below a HR of 70 bpm,as determined by receiver operator characteristic（ ROC） curve,the mean image quality score was 4. 32 compared with 3. 94 with HR of〉70 bpm（Z=-6. 701,P=0. 00）, 0 . 8%of coronary segments were non-diagnostic compared with 5 . 1%with HR of〉70 bpm （χ2=17. 210, P = 0. 00 ）. The relationship between HR and image quality was negative correlation. Conclusion：PGA coronary CT angiography using 60%acquisition phase and 200 ms padding time settings could offer assessable image quality at intermediate HR.