双能CT成像在分次团注双期CTU中的临床应用

Application of dual energy CT in split-bolus 2-phase CT urography

目的:探讨分次团注双期CTU检查时双能CT成像的临床应用价值。方法:48例血尿待查患者分为两组,试验组24例,行全泌尿系CT平扫及分两次团注对比剂后行肾实质-肾盂期CTU扫描;对照组24例,行全泌尿系CT平扫及单次团注对比剂后行实质期和肾盂期双期增强扫描。实验组的肾实质-肾盂期图像的采集采用高低压瞬切双能CT扫描模式(GSI),其它所有期相的图像采集均采用普通CT扫描模式。在工作站上使用GSI后处理软件获得实质-肾盂期最佳keV图像。将CTU图像中集合系统分段,测量实验组的肾实质-肾盂期最佳keV图像和对照组的肾盂期图像中集合系统各段管腔内的CT值,并计算对比噪声比(CNR)。记录所有病例完成CTU全部检查序列的有效辐射量。两组病例CT值、CNR和有效辐射量的比较使用非参数秩和检验。结果:分次团注CTU实质-肾盂期最佳keV图像各段集合系统腔内CT值均高于常规CTU肾盂期图像,其差异有统计学意义(P<0.05)。分次团注CTU实质-肾盂期最佳keV图像与常规CTU肾盂期图像各段集合系统CNR差异没有统计学意义(P>0.05)。分次团注CTU完成全部检查的有效辐射量(平均17.6mSv)明显低于常规CTU(平均25.8mSv),差异有统计学意义(P<0.05)。结论:双能CT成像用于分次团注双期CTU在降低辐射量同时,可获得与常规单次团注双期CTU相同的泌尿系成像质量。

Objective：To evaluate the effect of fast kVp switching dual energy CT in split-bolus 2-phase CT urography.Methods：Forty-eight patients with hematuria were recruited in this study.Group A：Twenty-four of them underwent split-bolus 2-phase CTU examination.The images of nephrographic-pyelographic phase were acquired with fast kVp switching dual-energy CT mode（gemstone spectral imaging mode,GSI）.Images of optimal keV were calculated by the workstation.Group B：The other twenty-four patients underwent single-bolus 3-phase CTU examination as a control.The CT value in the lumen of collecting system of each patient was measured segmentally.The CT values and CNR of each segment of different collecting system segments were compared between the two groups.The radiation dose of each examination was recorded.Mann-Whitney rank sum test was used for statistical analysis.Results：There was significant difference in CT values in lumen of each segment between the two groups（P0.05）.The CT values of every segment of Group A were significantly higher than those of Group B.There was no significant difference in CNR of each segment of urinary tract between the two groups（P0.05）.Effective radiation doses of split-bolus 2-phase CTU on fast kVp switching dual energy CT were less than those of single-bolus 3-phase CTU（P0.05）.Conclusion：Images acquired by the two techniques are the same in imaging quality,while the new split-bolus 2-phase examination on fast kVp switching dual energy CT can reduce the efficient radiation exposure but does not need more iodinated contrast agent.