能谱 CT 冠状动脉成像中双低技术的应用研究

目的：探讨能谱 CT 低辐射剂量结合低浓度对比剂在冠状动脉血管成像中的应用。方法60例疑诊冠心病患者随机分为 A、B 2组,每组30例。A 组使用350 mg I/mL 对比剂、行常规 CT 扫描,B 组使用300 mg I/mL 对比剂、行宝石能谱低剂量 CT扫描。均采用前瞻性心电门控扫描模式。扫描后 A 组常规重建40%ASiR 序列,B 组重建单能量65 keV、40%ASiR 序列轴面图像,传入 AW4.6工作站重建分析。由2名有经验的医师进行双盲法主观评分；测量主动脉窦部(AS)、左主干(LMA)、左前降支近端(LAD-p)、左回旋支近端(LCX-p)、右冠状动脉近端(RCA-p)CT 值,AS 的噪声(SD)、心包内脂肪 CT 值及 SD,计算信噪比(SNR)、对比噪声比(CNR)。记录 CTDI、DLP,计算有效辐射剂量(ED)。记录碘摄入量。采用两独立样本 t 检验比较2组患者的ED、碘摄入量、平均 CT 值、SD、SNR、CNR。结果2组间图像质量主观评分差异和冠状动脉测量段 CT 值差异均无统计学意义。B 组的 ED 较 A 组降低约29%,差异有统计学意义。碘摄入量 B 组较 A 组减少了约16%。结论冠状动脉 CT 血管成像时,应用能谱低辐射剂量扫描,重建最佳单能量图像,能有效降低辐射剂量和碘摄入量,可获得与常规扫描相当的图像质量。

Application research on low radiation dose and low concentration of contrast medium of energy spectrum CT in the imaging of the coronary arteries

Objective To explore the application of low dose of radiation combined with low concentration of contrast medium in the energy spectrum CT of the coronary artery angiography.Methods 60 patients with suspected diagnosis of coronary heart disease were randomly divided into A,B two groups,30 cases in each group.Group A with 350 mg I/mL contrast agent,undergoing conventional CT scanning;Group B using 300 mg I/mL contrast agent,the gems energy spectrum CT scanning with low-dose.Two groups both adopted forward-looking heart switch control scanning mode.After scanning,group A reconstructed conventional images of 40% ASiR sequence,group B rebuilded axial surface images of single energy 65 keV and 40% ASiR sequence,all the reconstruction images were introduced to AW4.6 workstations used for analysis.Double-blind subjective rating was done by two experienced doctors to measure CT values and SD of aortic sinus (AS),left main (LMA),the left anterior descending branch proximal (LAD-p),left circumflex branch proximal (LCX-p), right coronary artery proximal (RCA-p)and pericardial fat,AS the noise (SD),to calculate the signal-to-noise ratio (SNR)and contrast to noise ratio (CNR),to calculate the effective doses of radiation(ED)by recording CTDI and DLP,and to record iodine intake.By using two independent samples t test to compare two groups of patients’the effective radiation doses,iodine intake,the average CT value,SD,SNR and CNR.Results The subjective image quality score differences and coronary measuring section CT values between the two groups had no statistical significance.In the aspects of effective radiation dose,group B reduced about 29% compared to group A,the difference was statistically significant.Iodine intake in group B decreased about 16% than in group A.Conclusion In coronary artery CT imaging, spectral scanning with low dose of radiation and reconstruction images with single energy can effectively reduce the radiation dose and iodine intake,at the same time it can obtain the approximate image quality like conventional scanning.