第二代双源CT Flash Spiral模式高心率冠状动脉成像的图像质量及准确性评价

目的评价第二代双源CT大螺距前瞻性螺旋扫描（Flash Spiral）高心率冠脉成像的图像质量、准确性及有效射线剂量。方法前瞻性入选心率〉65次／min的连续性患者268例，随机分为两组。A组134例，采用Flash Spiral模式扫描，采集图像时间为RR间期20％-30％；B组134例，采用回顾性心电门控扫描模式（Spiral）扫描。30d内A组有47例行冠状动脉造影术（CCA）检查（A1组），B组中有45例行CCA检查（B1组）。比较两组患者一般情况、图像质量评分、图像噪声、对比信噪比（CNR）和有效射线剂量。以CCA结果为金标准，分别计算A1、B1两组FlashDSCT显示冠脉病变的敏感性、特异性、准确率、阳性预测值和阴性预测值。结果①两组患者一般情况比较差异无统计学意义。②两组不可诊断节段基于血管节段评价分别为1．52％和1．74％，基于患者评价分别为7．5％和6．7％，差异均无统计学意义（P=0．345，P=0．812）。两组图像质量评分均数分别为1．064±0．306和1．084±0．327，差异无统计学意义（P=0．063）。A组平均图像噪声19±27（21．4±4．5）HU，CNR6．4-25．3（12．1±4．2）：B组分别为19±28（20．9±4.3）HU和7．1-28．2（13．8±5．1），两组比较差异无统计学意义。③心率变异性：A组图像质量评分3分的病例平均心率变异性明显小于B组。④与CCA比较，两组患者评价冠状动脉狭窄的敏感性、特异性差异均无统计学意义。⑤射线剂量：A组平均有效射线剂量显著低于B组（1．04±0．16）mSv比（7．05±1．05）mSv，P=0．001]。结论高心率患者（心率〉65次／min）采用Flash双源CT大螺距前瞻性心电门控螺旋扫描在RR间期20％±30％成像，图像质量、准确性与回顾性心电门控扫描接近，而有效射线剂量显著减低。心率变异性对高心率患者FlashSpiral模式扫描图像质量的影响较大。

The image quality and diagnostic accuracy of high-pitch dual-source coronary angiography using flash spiral mode in patients with high heart rates

Objective To investigate the image quality, diagnostic accuracy and radiation doses of prospectively ECG-triggered spiral acquisition mode（Flash Spiral mode）coronary computed tomography angiography （CCTA） using high-pitch dual-source CT in patients with high heart rates, compared with retrospectively ECG- gated spiral acquisition mode（Spiral mode） and catheter coronary angiography（CCA）. Methods Two hundred and sixty-eight consecutive patients with mean HR〉65 beats per minute （bpm） were prospectively included in this study. The patients were divided into two groups. Collection in group A （134 patients） was performed CTCA usingflash mode setting at 20%-30% of the R-R interval, while group B （134 patients ） used retrospectively ECG-gat- ed spiral acquisition mode to acquire data. Among them, there were 47 cases in group A （as group A1） and 45 cases in group B （as group B1 ） were underwent CCA. The general characteristics, image quality scores, the image noise, contrast-to-noise ratio （CNR） and effective radiation dose between two groups were assessed. Considered CCA as the standard of reference, the sensitivity, specificity, positive predictive value and negative predictive val- ue of two groups were calculated. Results （1）There were no significant differences in general characteristics between the two groups （all P〉0.05）. （2）The non-diagnostic coronary artery segments were no significant differences between group A and group B （segment-based analysis 1.52% vs 1.74%, P=0.345, patients-based analysis 7.5% vs 6.7%, P=0.812）. There were no significant differences in the image quality scores 1.064±0.306 （group A） vs 1.084±0.327 （group B）, P=0.063±. The average image noise was 19-27 ±range （21.4±4.5）HU] and CNR was 6.4-25.3（range： 12.1±4.2） in group A, and the corresponding numbers were 19-28range： （20.9_±4.3）HU] and 7.1-28.2 （range： 13.8±5.1） in group B. There were no significant differences in image noise or CNR between the two groups. （3）The average HRV of score 3 in group A was significantly lower than that in group B. （4）The sensitivity, specificity and positive and negative predictive values of two groups were no significant differences. （5）The average effective radiation doses of groups A was significantly lower than that of group B. Conclusion In pa- tients with high heart rates（ 〉65 bpm）, compared with the retrospectively ECG-gated spiral acquisition mode, the prospectively high-pitch spiral acquisition mode with image acquired timing set at 20%-30% of the R-R interval provides a similar image quality and diagnostic accuracy, while being associated with significant reduction of radia- tion exposure in patients with high heart rates. The HRV is a considerable factor which affects the image quality of high-pitch dual-source CCTA in patients with high heart rates.