能谱CT肠系膜静脉成像技术优化研究

Optimization study of spectral computed tomography venography on mesenteric vein

目的:探讨肠系膜静脉能谱CT增强扫描技术的优化方案。方法:前瞻性搜集2019年12月-2020年12月昆明医科大学第一附属医院行腹部增强CT检查的280例患者,根据扫描方式(常规组与能谱组,各50例)、对比剂注射速率(3.0 mL/s、3.5 mL/s、4.0 mL/s组,各30例)、动脉期后延迟时间(15 s、20 s、25 s组,各30例)将280例患者分为8组。图像质量客观评价为测量每组图像同一层面SMV-CT值、竖脊肌CT值和SD,并分别计算各组图像的CNR。主观评价为2名诊断经验丰富的影像科医师对每例受检者的VR、MIP及TSMIP重建图像进行5分评分法。常规组与能谱组图像质量比较采用两独立样本t检验。不同注射速率组、不同延迟时间组图像质量比较采用方差分析,两两比较采用LSD法。结果:能谱组与常规组的SMV-CT值、SD差异有统计学意义(P<0.05)。不同注射速率组SMV-CT值、竖脊肌CT值、SD、CNR差异无统计学意义(P>0.05)。不同延迟时间组SMV-CT值、SD、CNR差异有统计学意义(P<0.05)。结论:肠系膜静脉CT成像中能谱扫描优于常规参数扫描,且对比剂注射速率推荐3.0~4.0 mL/s,动脉期后延迟时间为20~25 s。

Objective:Explore the optimization scheme of spectral CT scanning technology on mesenteric vein.Methods:A prospective analysis of abdominal enhanced CT data from 280 patients at the First Affiliated Hospital of Kunming Medical University.280 patients were divided into 8 groups based on the scanning method(50 cases in the conventional group and spectral group,respectively),injection rate of contrast agents(30 cases in the 3.0mL/s,3.5mL/s,and 4.0mL/s groups,respectively),and delay time after arterial phase(30 cases in the 15s,20s,and 25s groups,respectively).The objective evaluation of image quality was to measure the SMV-CT values,CT values,and SD of images at the same level in each group,and to calculate the CNR of images separately.Subjective evaluation was performed by two experienced radiologists,who made the image quality scores on the VR,MIP,and TSMIP reconstructed images independently.Independent sample t-tests were used to compare the image quality between conventional and spectral groups.The comparison of image quality among different injection rate groups and different delay time groups was conducted by using analysis of variance,LSD was used for pairwise comparison.Results:CT value of the superior mesenteric vein,image noise and subjective scores of the spectral group are higher than that of the conventional group,which shows significant differences(P<0.05).While,there is no significant difference between the different injection rate groups(P>0.05).There were significant differences in SMV-CT values,SD,and CNR among different delay time groups(P<0.05).Conclusion:In mesenteric vein CT imaging,spectral scanning is superior to conventional scanning,and the recommended injection rate of contrast agents is 3.0~4.0mL/s,with delay time of post-arterial phase is 20~25s.