迭代重建算法在低剂量冠状动脉成像中的初步应用

Initial Application of Iterative Reconstruction (iDose) in Coronary Computed Tomography Angiography with Low-Dose

目的对比低剂量冠状动脉成像使用迭代重建算法(iDose)与标准剂量冠状动脉成像使用滤过反投影法(FBP)的剂量与图像质量。方法采用256层螺旋CT,选取120例临床拟诊为冠心病的患者,对于心率≤65次/min的患者采用前瞻性门控扫描方式,心率>65次/min的患者采用回顾性门控扫描方式。将120例随机分为低剂量组和常规剂量组。对比分析两种扫描方式下低剂量和常规剂量的图像质量及辐射剂量。低剂量组均使用迭代重建算法(iDose)行图像重建,常规剂量组均使用FBP行图像重建。将冠状动脉主要分支分为9个节段评价,采用4分法评价图像质量,图像质量、噪声和有效剂量(ED)测量记录用于图像评价。结果回顾性门控扫描常规剂量组与低剂量组平均ED分别为8.29±1.22和4.29±1.22,低剂量组较常规剂量组剂量降低了49%(P<0.01);前瞻性门控扫描常规剂量组与低剂量组平均ED分别为3.03±0.53和1.40±0.13,低剂量组较常规剂量组剂量降低了54%(P<0.01);回顾性门控扫描方式和前瞻性门控扫描方式下常规剂量组和低剂量组图像的主观评分、图像信噪比、对比信噪比及降主动脉噪声差异均无统计学意义(P>0.05)。结论使用iDose可以在保证图像质量的同时进一步降低辐射剂量。

Objective To investigate the image quality and radiation dose of low radiation dose CT coronary angiogra- phy（CCTA） using iterative reconstruction（iDose） compared with standard dose CTCA using filtered back-projection（FBP）. Methods Image quality and radiation exposure were systematically analyzed in 120 patients. Patients with heart rate lower than 65bpm were used prospective CCTA ,while patients with heart rate higher than 65bpm were used retrospective CCTA. All of the patients were randomly divided into low-dose group and conventional dose group, each of the group had 30 pa- tients. Iterative reconstructions were used for reconstruction in low-dose group and filtered back projection（FBP） were used in conventional dose group. Image quality was assessed using a 4-grade scale（4 = best to 1 = worse） in consensus of 2 expe-rienced observers, and signal-and contrast-to-noise ratios （SNR and CNR）were quantified. Results For retrospective CCTA scanning, the effective radiation dose of low-dose group and conventional-dose group were 8.29 ± 1.22 and 4.29 ± 1.22, by 49% of radiation dose decreased. For prospective CCTA scanning, the effective radiation dose of low-dose group and conventional-dose group were 3.03 ± 0.53 and 1.40 ± 0.13, by 54% of radiation dose decreased . The coronary artery image quality scores, image noise, SNR and CNR had no significantly different between 2 groups （ P 〉 0.05 ） . Conclusion Compared with standard dose CCTA using FBP,low dose CCTA using iDose can get high quality imagings, meanwhile re-duce radiation dose.