双源CT低电压迭代重建联合分次注射法低辐射泌尿系造影的可行性研究

The feasibility of dual-source CT using low voltage scan and iterative reconstruction combine with split-bolus injection to reduce radiation dose in urography

目的评估双源CT（DSCT）低电压迭代重建联合分次注射法（SBI）行CT泌尿系造影（CTU）的辐射剂量、图像质量和影像诊断准确率。方法连续80例临床初诊为泌尿道疾病而准备行CTU检查的患者依据随机数字表法分为对照组和试验组两组。对照组40例采用常规注射，常规电压（120kV），滤波反投影法（filtered back—project，FBP）重建，试验组40例采用分次注射法，低电压扫描（80kV），正弦迭代重建（sinogram affirmed iterative reconstruction，SAFIRE），评估两组的有效剂量E、图像质量及影像诊断准确率。结果共77例患者顺利完成检查和图像评估，其中对照组39例，试验组38例。试验组的平均有效剂量E为（3．93±0．85）mSv，低于对照组的（26．68±4．07）rosy（t=-33．78，P〈0．05）。两组图像质量主观评分分别为（4．49±0．79）分和（4．39±1．53）分，差异无统计学意义（P〉0．05）。试验组的信噪比（SNR）为127．3±15．9，明显高于对照组的109．6±13．2，差异有统计学意义（t=4．49，P〈0．05），但对比噪声比（CNR）分别为100．84±12．92和108．96±14．42，差异无统计学意义（P〉0．05）。两组最终诊断准确率分别为84．62％和81．58％，差异无统计学意义（P〉0．05）。结论双源CT低电压扫描迭代重建联合分次注射法CTU检查可大幅度降低辐射剂量，但图像质量主观评分、CNR值和影像诊断准确率未受明显影响。

Objective To evaluate the image quality, diagnosis accuracy and dose reduction of split-bolus CT urography （CTU） with low vohage scan and sinogram affirmed iterative reconstruction （SAFIRE）. Methods A total of 80 cases of consecutive patients with confirmed or suspected urinary system disease needed CTU examination were divided into two groups （control group and test group） by using random number table. In control group, convention scan （ 120 kV） with one time injection was used. But low voltage scan （80 kV） with SAFIRE algorithm and split-bolus injection （SBI） was used in experiment group. The radiation dose, image quality and diagnosis accuracy were compared. Results A total of 77 cases completed CTU examination successfully in the two groups, including 39 cases in control group and 38 cases in test group. The effective dose reduced from （26.68 ±4.07） in control group to （3.93 ± 0. 85 ） mSv in test group （ t = - 33.78, P 〈 0. 05 ）. Subjective image quality score was （4.49 ± 0. 79） in control group and （4. 39 ± 1.53） in test group , with no significantly statistical difference （Z = 2. 71, P 〉 0. 05 ）. Signal-to-noise ratio （SNR） of objective image quality in test group was higher than that in control group （127.3±15.9 vs. 109.6 ± 13.2,t =4.49, P〈0.05）. But there was no significantly statistical difference in contrast-to-noise ratio （CNR） between control group（ 100.8 ±12.9） and test group （ 109. 0 ±14. 4, P 〉 0. 05 ） . For diagnosis accuracy, no statistical difference were found between two groups（ 84. 62% and 81.58% , P 〉 0. 05 ）. Conclusions The combination of low voltage scan with SAFIRE algorithm and split-bolus injection CTU could reduce the radiation dose significantly, but the objective image quality, CNR （except SNR） of subjective image quality and diagnosis accuracy were all unaffected obviously.