目的:比较第二代双源CT前门控大螺距螺旋扫描(FLASH扫描)与序列扫描模式在冠状动脉CT成像中的图像质量及辐射剂量。方法:回顾性分析采用第二代双源CT行前门控FIASH扫描(A组)与序列扫描(B组)冠状动脉CTA连续各50例患者,入组标准为心率70次/min以下,窦性心律,心率波动范围在10次/min以内。评价这2种成像模式的图像质量及辐射剂量。扫描参数:2组均采用Z轴飞焦点技术采集,探测器准直宽度0.6 mm,重建层厚0.75 mm,扫描时间0.28 s/r,单扇区时间分辨率75 ms,根据患者体质量指数(BMI)值设定管电压:100kV(BMI<24 kg/m~2)、120 kV(BMI≥24 kg/m~2),参考管电流370 mAs,采用管电流调制方案;FLASH扫描前门控心电触发选在60%R-R间期,螺距3.4;序列扫描采集时相为35%～75%R-R间期,步进采集宽度34.5 mm。冠状动脉图像质量分为4级(1级为优异,1～3级为可评价血管,4级为不可评价血管),相应评为1～4分。应用秩和检验比较2组患者冠状动脉段图像质量评分,应用两独立样本t检验比较2组患者所接受的辐射剂量。结果:A、B 2组患者的年龄及BMI差异无统计学意义。A、B 2组可评价的冠状动脉节段百分比分别为98.21%和98.56%,差异无统计学意义(χ~2=0.244,P=0.621),平均图像质量评分分别为1.30±0.60和1.28±0.56,差异无统计学意义(Z=-0.489,P=0.625)。A、B 2组扫描的平均有效辐射剂量分别为(0.99±0.34)mSv和(4.80±2.21)mSv,差异有统计学意义(t=-12.048,P=0.000),FLASH扫描剂量明显低于序列扫描。结论:在心率低于70次/min、心律稳定的情况下,第二代双源CT前门控FLASH扫描可获得与序列扫描相似的高质量图像,但辐射剂量明显降低。 Objective: To compare the image quality and radiation dose of second-generation dual-source CT front-gate large-pitch helical scan (FLASH scan) and sequential scan mode in coronary CT imaging. Methods: A retrospective analysis of 50 consecutive patients with coronary artery CTA using the second-generation dual-source CT scan with frontal gated FIASH scanning (group A) and sequential scanning (group B) was performed. The standard was 70 beats / min, Heart rate, heart rate fluctuations in the range of 10 times / min. The image quality and radiation dose of these two imaging modes were evaluated. Scan parameters: Both groups were collected by Z-axis fly-focus technique. The collimation width of the detector was 0.6 mm, the reconstruction layer thickness was 0.75 mm, the scan time was 0.28 s / r, the single sector time resolution was 75 ms. According to the patient’s body mass index BMI) set the tube voltage: 100kV (BMI <24 kg / m ~ 2), 120 kV (BMI≥24 kg / m ~ 2), reference tube current 370 mAs, using tube current modulation scheme; Electrical triggering was selected at 60% RR interval with a pitch of 3.4; 35% -75% RR interval was acquired during the sequence scan acquisition, and the acquisition width was 34.5 mm. Coronary artery image quality was divided into 4 grades (Grade 1 was excellent, grade 1 to grade 3 were evaluable blood vessels and grade 4 was not evaluable blood vessels), and the corresponding scores were 1 to 4 points. Rank rank test was used to compare the image quality score of coronary artery in two groups of patients. The two groups were compared by two independent samples t-test. Results: There was no significant difference in age and BMI between group A and group B 2. The percentages of coronary artery segments that can be evaluated in group A and group B were 98.21% and 98.56% respectively, with no significant difference (χ ~ 2 = 0.244, P = 0.621). The mean image quality scores were 1.30 ± 0.60 and 1.28 ± 0.56, the difference was not statistically significant (Z = -0.489, P = 0.625). The average effective dose of scanning in group A and group B was (0.99 ± 0.34) mSv and (4.80 ± 2.21) mSv respectively, with statistical significance (t = -12.048, P = 0.000) scanning. CONCLUSION: In the case of stable heart rate at 70 beats / min and heart rate, the second-generation dual-source CT front-gate FLASH scan can obtain high-quality images similar to the sequence scan, but the radiation dose is obviously reduced.