320层容积CT超低剂量扫描在冠状动脉成像中的应用

Application value of low radiation dose coronary angiography using 320-slice volume CT

目的评价320层CT冠状动脉成像中前瞻性轴面容积扫描不同kV设置对辐射剂量及图像质量的影响，探讨〈1mSv冠状动脉检查的可行性及应用价值。方法从拟行冠状动脉成像的患者中连续选取80例，随机分成A、B两组各40例，A组扫描时管电压为100kV，B组为120kV。A组经AIDR软件重建后成为A1组。比较A、B两组升主动脉根部平均强化CT值（sI）、噪声（SD）、信噪比（SNR）、对比信噪比（CNR）、有效辐射剂量（E）及图像质量评分。分别比较A、A1和B、A1组间患者SI、SD、SNR、CNR及图像质量评分。结果A组有效辐射剂量为（0．67±0．18）mSv，B组为（3．08±1．04）mSv（t=-14．30，P〈0．05），平均减少了78％。A、B两组的图像质量评分分别为（4．57±0．57）和（4．59±0．59）分（t=-1．17，P〉0．05）。A、B组SI、SD、SNR、CNR分别为（570．8±131．5）HU、25．1±6．9、24．5±9．1、19．8±6．1和（460．6±14．3）HU、15．1±3．6、31．7±7．7、29．3±6．8。两组SI、SD比较，A组大于B组，差异有统计学意义（t=4．49、8．18，P〈0．05）；SNR、CNRA组小于B组，差异有统计学意义（t=-4．24、-6．19，P〈0．05）。A1组SI、SD、SNR、CNR、图像质量评分为（557．9±24．5）HU、21．1±6．0、27．7±10．0、23．4±7．8、（4．60±0．56）分，与A组相比，sI、图像质量评分差异无统计学意义（t=1．09、-1．90，P〉0．05）；SD、SNR、CNR差异有统计学意义（江-5．97、-4．18、-6．22，P〈0．05）。结论320层CT冠状动脉成像前瞻性轴面容积扫描中，采用100kV管电压扫描，其辐射剂量可降到1roSy以下，并且图像质量达到诊断要求。

Objective To evaluate the image quality and radiation dose of prospective electrocardiography-triggered coronary 320-slice volume CT angiography with different kV, and the feasibility of coronary scan with 〈 1 rosy radiation dose. Methods Eighty consecutive patients were randomly divided into two groups equally. The tube voltage according to paradigm was 100 kV in group A and 120 kV in group B. All raw data in group A was reconstructed by the software AIDR in CT system to create a new group named as A1. Such parameters as the mean intraluminal attenuation （SI）, noise （SD） , signal-to-noise ratio （SNR） , contrast-to-noise ratio （CNR） ,effective radiation dose（E） and image quality score measured in group A were compared with those in group B. The values such as SI, SD, SNR, CNR, image quality scores were compared between group A and group A1. The significance of group B and group A1 was compared in SI, SD, SNR, CNR, image quality scores as well. Results E in group A was significantly lower than that in group B[ E = （0. 67 ± 0. 18） mSv in group A vs. E = （3.08 ± 1.04） mSv in group B]. The value of E in group A was decreased by 78% compared to group B（t = - 14. 30, P 〈 0. 05 ）. There was no significant difference in mean image quality scores between two groups（4. 57 ± 0. 57 in group A vs. 4.59 ± 0.59 in group B, t= -1.17, P〉0.05）. The values ofSI, SD, SNR, CNR in group A were （570.8 ± 131.5）HU, 25.1 ±6.9, 24.5 ±9.1, 19.8 ±6.1. And the values of SI, SD,SNR, CNRin group B were （460.6 ± 14.3） HU, 15.1 ±3.6, 31.7±7.7, 29.3 ±6.8. The values of SI and SD in group A were significantly higher than those in group B（t =4.49,8. 18, P 〈0.05）. The values of SNR and CNR in group A were lower than those in group B （t = -4.24, -6. 19, P〈0.05）. The values of SI, SD, SNR, CNR,image quality scores in group A1 were （557.9 ± 24.5 ） HU, 21.1 ± 6.0, 27.7 ±10.0, 23.4±7.8, 4. 60 ± 0.56. There was no difference in the SI and the image quality scores between group A and group A1 （t = 1.09, - 1.90, P 〉 0, 05）. Conclusions 320-slice volume CT with 100 kV tube voltage and prospective ECG-triggered technique can reduce the radiation dose to less than 1 mSv and obtain optimal images in diagnosis of coronary arterial diseases.