低剂量冠状动脉CTA:前瞻性与回顾性心电门控扫描的对比分析

摘要

目的：对比分析前瞻和回顾性心电门控双源CT冠状动脉成像时辐射剂量及图像质量的差异，为临床低剂量冠状动脉CT成像扫描方案的制定提供参考依据。方法：回顾性分析105例双源CT冠脉成像资料，前瞻性门控扫描组55例，应用自动管电流调制技术(ATCM)40例，未应用ATCM技术15例。回顾性扫描组50例均采用ATCM技术、ECG管电流自动调制技术及螺距-心率自动匹配技术。计算所有患者CTA检查的辐射剂量，对所有冠脉节段(直径≥1 mm)进行图像质量评分(采用4分法，1～3分能用于诊断，4分不能用于诊断)。结果：①未应用ATCM前瞻组、应用ATCM前瞻组、回顾扫描组的有效辐射剂量分别为(6.02±0.61)、(4.46±1.04)和(6.61±2.26)mSv，三组间两两比较，应用ATCM前瞻组与未应用ATCM前瞻组及回顾组间差异有极显著性意义(P＜0.001)，未应用ATCM前瞻扫描与回顾组比较差异无统计学意义(P＝0.24)。②前瞻扫描-ATCM组15例患者共评价冠脉197段，能够满足诊断的图像(≤3分)比例为100％，评价为优的冠脉节段比例为95.93％。前瞻扫描+ATCM组40例患者共评价冠脉554段，能够满足诊断的图像(≤3分)比例为99.27％，评价为优的冠脉节段比例为96.93％。回顾扫描组共评价冠脉645段，能够满足诊断的图像(≤3分)比例为98.76％，评价为优的冠脉节段比例为88.99％。结论：前瞻扫描与回顾扫描均可提供优秀的、可供临床诊断的图像。前瞻扫描是减少辐射剂量的最有效方式，但较低且平稳的心率仍是其获得优质图像的有力保证。应用各种降低辐射剂量的措施，回顾扫描在不控制心率的情况下一样能达到较低的辐射剂量。%Objective:To analyze the differences of radiation dose and image quality of prospectively ECG-gated versus retrospectively ECG-gated coronary angiography with dual source CT,in order to provide a desirable scanning procedure for the clinical application of low dose coronary CT angiography. Methods: 105 patients who were referred for coronary CT angiography with dual source CT scanner were enrolled, with prospective group (PG,55 cases) including application of automatic tube current modulation (ATCM) scanning technique (40 cases) and without application of ATCM (15 cases). For the retrospective group (RG),all of them had ATCM technique applied, with ECG automatic tube current modulation and pitch-rate matching technology. The radiation dosages were calculated and the image quality of all coronary segments (diameter ≥1mm) was evaluated and scored. Results:①The mean radiation dosage of PG without ATCM, with ATCM and RG was (6. 02±0. 61),(4. 46±1. 04) and (6. 61 ±2. 26)mSv,respectively, with significant statistical difference (P<0. 001) between PG group with ATCM and PG group without ATCM and RG group, whereas,no statistical difference was existed between PG without ATCM and RG (P=0. 24). ②Of the 15 cases in PG without ATCM, 197 segments of coronary artery were showed,the percentage of assessed coronary artery segments with the image quality fulfilled the requirement of diagnosis (≤3 points) was 100%,and scored as excellent was 95. 93%. As for PG with ATCM (40 cases),554 segments of coronary artery were showed,the image quality was satisfactory for diagnosis (≤3 points) was 99. 27% and scored as excellent was 96. 93%. 645 segments of coronary artery were revealed in RG,98. 7% could fulfill the requirement of diagnosis and 88. 99% were excellent. Conclusion: Excellent/satisfactory image quality for clinical diagnosis could be provide by PG or RG scanning. PG is the most effective approach for the reduction of dosage,yet low and stable heart rate were indispensable for high image quality. With various procedures of radiation dosage reduction,low radiation dose could also be achieved with RG without heart rate control.