冠状动脉搭桥术后低剂量CTA成像的初步研究

Study on the low- dose CTA after coronary artery bypass grafts

目的探讨i Dose4迭代重建算法结合前瞻性心电门控技术在冠状动脉搭桥术后低剂量CTA成像中的应用价值。方法采用256层螺旋CT,选取26例拟行冠状动脉CTA检查的搭桥术后患者,随机分为2组,即回顾性心电门控扫描组(37支桥血管)和前瞻门控扫描组(34支桥血管),图像重建均采用i Dose4迭代重建算法。对图像质量进行主观评价,测量2组左右冠状动脉及桥血管的CT值、噪声、SNR和CNR,对比分析2组冠状动脉及桥血管的客观图像质量与辐射剂量。结果前瞻性心电门控组及回顾性心电门控组CT值、图像噪声、左右冠状动脉及桥血管的SNR、CNR差异均无统计学意义(P>0.05);前瞻性心电门控组与回顾性心电门控组主观图像质量比较,差异亦无统计学意义(P>0.05)。回顾性心电门控组及前瞻性心电门控组辐射剂量,分别为(10.0±2.1)ms V、(2.1±0.4)ms V,2组间差异有统计学意义(P<0.05),前瞻性心电门控组较回顾性心电门控组辐射剂量降低79.0%。结论采用256层螺旋CT前瞻性心电门控技术,应用i Dose4迭代重建技术,既保证了桥血管可评估率及图像质量,又可显著降低辐射剂量,是冠脉搭桥术后随访的有效方法。

Objective To investigate the application value of iDose4 iteration reconstruction and prospective ECG-gated scanning in low radiation dose scanning of computed tomography angiography （CTA） after coronary artery bypass grafts （CAGA）. Methods Using 256-slice CT,26 patients were collected and randomly divided the retrospective ECG-gated scanning and prospective ECG-gated scanning, and iDose4 iterative reconstruction. The difference between prospective ECG-gated and retrospective ECG-gated image quality and radiation were compared;the difference of image noise,CT values,CNR,SNR between ECG-gated iDose4 iterative reconstruction and the FBP recon？struction were studied prospectively. Results There was no significant difference between prospectively ECG-gated group and retrospective ECG-gated group on image quality （P〉0. 05）,as well as the image noise,CT values,SNR,CNR of left and right coronary artery. The effective radiation dose for the retrospective and prospective ECG-gated group was （10. 0 ± 2. 1） msV and （2. 1 ± 0. 4） msV,and there was significant difference between the two groups （P〈0. 05）,and ECG gated group radiation decreased 79. 0% prospectively. Conclusion 256-slice CT an？giography with prospective ECG-gated scanning and iDose4 iterative reconstruction can reduce radiation doses and maintain optimal image quality substantially.