前瞻心电门控大螺距低千伏扫描联合原始数据迭代重建冠状动脉CTA成像质量分析

目的：采用低千伏前瞻性心电门控大螺距（Flash spiral）扫描冠状动脉CTA成像，原始数据采用迭代重建，评价该扫描模式获得具有诊断价值图像质量的冠状动脉CTA的可行性。方法50例患者，体质量指数（body mass index BMI）＜30kg/m^2，心率≤60次/min。冠状动脉CTA成像采用前瞻性心电门控Flash spiral模式采集。原始图像重建采用两种重建方式，分别为反投影滤过重建及迭代重建。图像质量评分采用4分法。结果平均有效辐射剂量为（0.85±0.37） mSv。迭代重建的图像噪声降低，与反投影滤过重建比较具有统计学差异，数值分别为（26.4±5.2）和（20.6±4.1）HU。迭代重建的图像质量评分（1.9±1.1）降低，与反投影滤过重建（2.2±1.0）比较差异具有统计学意义（P〈0.0001）。728段冠状动脉段，反投影滤过重建有61段，迭代重建有38段被评为4分（P=0.07）。BMI指数为24-30 kg/m^2的患者，迭代重建的可评价图像噪声低，血管段SNR和CNR均比FBP重建高，且具有统计学意义。结论对于选择性人群，前瞻性心电门控大螺距低千伏扫描模式联合原始数据迭代重建可以提供充足的冠状动脉CTA图像质量。

Image Quality of Coronary CT Angiography Using High-Pitch Spiral Acquisition and Raw Data-Based Iterative Reconstruction

Objective To evaluate the potential of acquiring the diagnostic images of coronary CT angiography with prospective ECG-triggered high pitch flash spiral acquisition in low tube voltage combined with iterative reconstruction. Methods There were fitty patients whose BMI （ body mass index ） 〈30 kg/m^2 and heart rate ≤ 60/min, and their coronary CT angiography images were collected with prospective ECG-triggered high pitch flash spiral mode. The images reconstruction adopted the raw data-based filtered back projection （FBP） and iterative reconstruction （IR）. Image quality was assessed with a 4-point scale standard. Results The average effective dose was 0.85 ± 0.37 mSv. The noise of iterative reconstruction was significantly reduced, which is statistically different from the FBP. The data were （26.4 ± 5.2）HU and （20.6 ± 4.1） HU. The image quality score was lower for IR （1.9 ± 1.1）, which is statistically different from that of FBP（2.2 ± 1.0）（ P〈0.0001 ）. Among 728 coronary segments, there were 61 coronary segments of FBP and 38 segments of IR were scored 4 （P=0.07）. For patients whose BMI = 24 kg/m^2, the noise of evaluable image of IR was low. The SNR and CNR of coronary segments of IR were higher than those of FBP, which was statically important. Conclusion Prospective ECG-triggered high pitch flash spiral acquisition in low tube voltage combined with iterative reconstruction can provide sufficient image quality for selected patients.