320排CT单心跳冠状动脉成像的图像质量及辐射剂量分析

摘要

目的:探讨320排CT低心率患者单心跳冠状动脉血管成像的图像质量及辐射剂量.方法:将241例临床可疑或确诊冠状动脉疾病的患者分为三组:A组122例,心率＜65bpm;B组62例,65≤心率＜80bpm;C组57例,心率≥80bpm.扫描完成后选用最佳的时相,对冠状动脉进行容积重组(VR)、多平面重组(MPR)、曲面重组(CPR).按照4分法将图像质量分类并统计分析,用卡方检验比较冠状动脉血管段的优良率、可评价比例的差异；记录各组的辐射剂量,用秩和检验比较辐射剂量的差异.结果:A、B、C三组冠状动脉血管段优良率差异有统计学意义(x2=87.46,P＜0.05),可评价比例差异无统计学意义(x2 =3.99,P＞0.05).所有病例共有5段冠状动脉不可评价.A、B、C三组的平均辐射剂量分别为(3.79±2.32) mSv、(11.60±5.05)mSv、(16.52±6.36) mSv,其差异具有统计学意义(x2=149.11,P＜0.05).A组与B组、A组与C组、B组与C组辐射剂量两两比较差异均有统计学意义(Z值分别为-11.39、-8.47、-4.32,P值均＜0.017).结论:320排CT冠状动脉成像对于心率＜65bpm的患者可提供高质量的图像,且显著降低辐射剂量.%Objective:To evaluate the image quality and radiation dose for patients with heart rate (HR) below 65 beats per minnute (bpm) with prospective electrocardiogram (ECG)-triggering using 320-detector CT scanner. Methods: A total of 241 patients suspected or known coronary artery disease, who underwent coronary CT angiography using 320-detector CT scanner, were assigned three groups:group A (122 cases) with HR<65 bpm; group B (62 cases), with HR from 65 to 80 bpm; and group C (57 cases) with HR≥80 bpm. Following data acquisition, dataset with best phase were transferred to a workstation for further processing by means of VR, MPR, CPR. Based on 4-point likert scale, image quality was scored and categorized. Chi-square test was made for grade of image quality. Kruskal-Wallis test was performed to compare radiation dose. Results:Significant difference was found for good and excellent image quality among three groups (X2 =87. 46. P <0. 05). No significant difference was found for the rate of assessable image, (χ2 = 3. 99, P >0. 05). A sum of five segments of coronary artery were found not to be assessable. The effective dose of group A, B and C was on average (3. 79 + 2. 32) mSv. (11. 60±5. 05) mSv and (16. 52±6. 36) mSv, a significant difference showed in them (χ2 149. 11, P <0. 05). A significant difference was found between group A and B, A and C, B and C ( Z =-11. 39, -8. 47 , -4. 32, P <0. 017). Conclusion:Image quality is excellent and low radiation dose, which can be achieved for patients with HR<65 bpm using 320-detector CT scanner.