多层螺旋CT双低技术扫描在肺动脉血管成像中的应用

Application of multi-slice spiral CT double-low technique scan in pulmonary angiography

目的:探讨多层螺旋CT低辐射和低对比剂浓度(双低技术)扫描在肺动脉血管成像中应用的可行性。方法:①体模实验:分别用生理盐水将碘海醇稀释成16.0、11.1、7.7和5.4 g/L的碘溶液5 mL置于4个塑料软管中,管外包裹新鲜猪肉,制备成肺部血管模型;模型定位后采用西门子双源256排CT扫描仪进行扫描,管电压分别设置为80、120 kV,管电流分别设置为100、150、200、300 mA,采用iDose^(4)技术进行图像重建;计算重建图像的对比信噪比(CNR)、信号噪声比(SNR)。②人体试验:将60例临床高度疑似肺动脉栓塞患者分为对照组和观察组各30例,对照组采用常规扫描(管电压120 kV、管电流300 mA、碘海醇350 g/L),观察组采用双低技术扫描(管电压80 kV、管电流300 mA、碘海醇270 g/L),均采用iDose^(4)进行图像重建。比较两组重建图像的质量。结果:相同管电流不同管电压、不同碘浓度扫描图像CNR、SNR的差异均无统计学意义(P>0.05)。观察组与对照组比较,图像质量评分,肺动脉主干、左右肺动脉和左上叶肺动脉CT值,肺动脉主干CNR和SNR差异均无统计学意义(P>0.05);观察组静脉污染评分高于对照组,容积CT剂量指数、剂量长度乘积和碘摄入量均低于对照组(P<0.05)。结论:管电压80 kV、管电流300 mA、碘海醇270 g/L结合iDose^(4)重建可获得较满意的肺血管图像,安全性更好,可用于肺动脉栓塞的诊断。

Aim:To discuss the feasibility of multi-slice spiral CT low-radiation and low-concentration contrast medium(double-low technique)in pulmonary angiography.Methods:Firstly,the phantom experiment was carried out.Iohexol was diluted into four different concentrations of iodine solutions(16.0,11.1,7.7 and 5.4 g/L).The pulmonary vascular model was scanned with Somaton definition flash 256-row CT and iDose^(4) iterative reconstruction technology were applied.The tube voltage was set at 80 kV and 120 kV,and tube current was 100,150,200,300 mA.The contrast-to-noise ratio(CNR),signal-to-noise ratio(SNR)of the reconstructed image were calculated.Sixty patients with clinically highly suspected pulmonary embolism were allocated into control group and observation group,with 30 in each group.The control group was conventionally scanned(tube voltage 120 kV,tube current 300 mA,iohexol concentration 350 g/L),and the observation group was scanned with double-low technique(tube voltage 80 kV,tube current 300 mA,iohexol concentration 270 g/L),iDose^(4) was used for image reconstruction.The reconstructed image quality were compared.Results:There was no significant difference in CNR or SNR of plumonary vascular model under the same tube current with different iodine concentrations and tube voltage(P>0.05).Compared with the control group,there were no differences in image quality score,CT value of main pulmonary artery,left and right pulmonary artery and left upper lobe pulmonary artery,or CNR and SNR in the observation group(P>0.05).While the score of venous pollution in the observation group was higher than that of the control group(P<0.05),and CTDIvol,DLP and iodine uptake volume in the observation group were significantly lower than those in the control group(P<0.05).Conclusion:Multi-slice spiral CT double-low techniqne(tube voltage 80 kV,tube current 300 mA,iohexol concentration 270 g/L)combined with iDose^(4) reconstruction can obtain satisfactory pulmonary angiography,with a better safety and important application potential in pulmonary embolism diagnosis.