双源CT心脏“一站式”检查低剂量扫描方案在低心率患者中的应用

The Application of Low Dose "One Stop Shop" Cardiac Examination with Dual Source CT in Patients with Low Heart Rates

目的探讨双源CT(dual-source CT,DSCT)前瞻性心电门控"一站式"低剂量扫描方案在低心率患者冠状动脉成像及左心室功能分析中的应用价值。方法 33例临床怀疑或确诊为冠心病的患者1周内同时行冠状动脉DSCT和超声心动图检查。入组条件:心律规则且心率≤70次/分。DSCT采用管电流调制,前瞻性心电触发序列扫描,扫描窗宽为30%～80%R-R间期,全电流采集时相为70%R-R间期,其余时相使用全电流的20%。冠状动脉依据美国心脏学会冠状动脉16分段法,图像质量用4级法进行评估,1～3级图像为可评估,能用于影像诊断,4级为不可评估。采用手动矫正Simpson法计算DSCT所测得的左心室射血分数(LVEF),并以超声心动图测得的LVEF值为对照进行配对t检验和Pearson相关性检验。结果 30例患者顺利完成检查及左心室功能分析,1例心脏扫描失败,2例左心室功能分析失败。平均辐射剂量为(3.08±0.40)mSv。共评价冠状动脉409段,其中可用于诊断的节段占96.82%。双侧配对t检验结果显示DSCT与超声心动图测得的LVEF值差别无统计学意义(P=0.14),且有很高的相关性(r=0.74)。结论 DSCT前瞻性心电触发序列扫描低剂量"一站式"心脏检查方法可以用于低心率患者的冠状动脉成像和左心室功能分析。冠状动脉图像质量较好,左心室功能分析结果可靠,平均辐射剂量较低。

Objective To explore the application value of the low does ＂One stop shop＂ cardiac scan method with prospective ECG triggered dual source CT for coronary angiography and analysis of left ventricular function in patient with low heart rate.Methods 33 patients suspected or diagnosed with coronary disease were examined by cardiac DSCT and 2D echocardiography within one week.The criterion of selected patients were regular rhythm and low heart rates（≤70 bpm）.Prospective ECG trigger and adaptive sequential tube current modulation were used in DSCT with 30%-80% R R interval width scan window.Full tube current output at 70% phase and 20% full current output at other phase.Coronary artery was divided into 16 segments according to the American Heart Association.Image quality of coronary arteries were graded with 4 point scale（grade 1 ~ 3 can be used）.Manual correction Simpson method was used in LVEF calculation in DSCT. The LVEF of 2D echocardiography was used as control in paired t test and Pearson correlation analysis.Results 30 cases accomplished the examination and left ventricular analysis successfully.1 patient failed in scan and 2 cases failed in left ventricular analysis.The average radiation does was（3.08±0.40）mSv.In 409 evaluated coronary segments,96.82% could be used in diagnosis.Two tailed Paired t test indicated that the LVEF of DSCT and 2D echocardiography had no significant statistically differences（P=0.14）and the correlation was high（r = 0.74）.Conclusion The low does ＂One stop shop＂ cardiac scan method with prospective ECG triggered dual source CT can be used in coronary angiography and analysis of left ventricular function in patients with low heart rates.The image quality of coronary artery is higher and the left ventricular function analysis is reliable with average low dose radiation.