第三代双源CT冠状动脉成像三低扫描方案的初步经验

A protocol of low tube voltage,less contrast medium dosage and low flow rate for coronary angiography using 3^(rd)-generation dual-source CT:initial experience

目的:探究第三代双源CT(DSCT)前瞻性心电门控大螺距CT冠状动脉成像(CTCA)扫描模式下,应用70kv低管电压联合20mL低对比剂用量和3.0mL/s低注射流率的三低方案的可行性。方法:应用第三代双源CT对100例体质量指数(BMI)≤30kg/m^2、心率(HR)≤75次/分的患者行前瞻性心电门控大螺距CTCA检查。所有患者随机分为两组,采用2种扫描方案:A组48例,管电压80kVp,对比剂总量及流率分别为40mL和4.0mL/s;B组52例,管电压70kVp,对比剂总量及流率分别为20mL和3.0mL/s。测量动脉腔内CT值、图像噪声、信噪比(SNR)和对比噪声比(CNR)等客观指标以及Likert 4级主观评分法比较两组的图像质量,记录并比较两组的辐射剂量。结果:B组的图像噪声显著高于A组,但动脉(主动脉、左冠脉主干和前降支、右冠状动脉)腔内CT值均显著高于A组(P<0.05)。两组间SNR和CNR的差异无统计学意义(P>0.05),两组间图像质量评分的差异无统计学意义(P>0.05)。与A组相比,B组的有效辐射剂量减少了40%。结论:使用第三代DSCT结合三低扫描方案行前瞻性心电门控大螺距冠状动脉成像,可获得较为满意的图像质量,且辐射剂量、对比剂用量和流率均较常规扫描方案显著降低。

Objective：The aim of the present study was to explore the feasibility of a ＂triple-low＂ protocol [i. e. ,low tube voltage （TV） of 70kVp,less contrast medium （CM） of 20mL and injection rate （IR） of 3.0mL/s] for prospectively ECG-triggered high-pitch CT coronary angiography （CTCA） on a 3rd generation dual-source CT （DSCT） scanner. Methods：One-hundred patients with body mass index （BMI） 430.0kg/m2 and heart rate （HR）475 beats per minute （bpm） underwent prospectively ECG-triggered high-pitch CTCA using a 3r〈generation DSCT. All patients were randomly divided into 2 groups： group A, 48 patients, of conventional scan protocol with 80kVp, 40mL CM, and 4.0mL/s IR; group B, 52 patients,of a ＂triple-low＂ scan protocol with 70kVp,20mL CM and 3.0mL/s IR. Image quality was evaluated and com- pared by four objective parameters of intraluminal CT value [including aorta, left main coronary （LM）, left anterior descending branch （LAD） and RCA] ,image noise,signal-to-noise ratio （SNR） and contrast-to-noise ratio （CNR） as well as a subjective score （four-point Likert scale）. Radiation dose was also recorded and compared. Results： In group B,image noise was significantly higher than that of group A （P〈0.05） ; However, the intraluminal CT values of arota, LM, LAD and RCA in group B were significantly higher than those in group A （P〈0.05）. There was no significant difference in SNRs and CNRs between the two groups （P〉0.05）. Subjective image quality evaluation showed that no significant difference existed between the two groups （P〉0.05）. Compared with group A,the effective dose （ED） of group B was reduced by 40M. Conclusion：With 3ra-generation DSCT, prospectively ECG-triggered high-pitch CTCA with ＂triple-low＂ protocol can obtain satisfactory image quality. Meanwhile, the radiation dose,CM dosage and injection rate were significant decreased compared to the conventional protocol.