低浓度对比剂联合低管电压在CT肺动脉成像中的应用

The application of low concentration of contrast agent combined with low tube voltage in CT pulmonary angiography

目的探讨低碘浓度对比剂联合低管电压在CT肺动脉血管成像（CTPA）中的应用价值。方法60例临床怀疑肺动脉栓塞而行CTPA检查的患者纳入前瞻性研究，按随机数字表法分为3组（每组20例），A组：管电压120kV，对比剂碘含量350mgI／ml，滤波反投影（VBP）算法重建；B组：管电压100kV，对比剂碘含量280mgI／ml，三维自适应迭代剂量降低重建（AIDR3D）标准水平重建；C组：管电压80kV，对比剂碘含量245mgI／ml，AID3D高水平重建。记录各组CT容积剂量指数（CTDIvol）；测量各组图像的肺动脉强化CT值和背景噪声；计算信噪比（SNR）、对比噪声比（CNR），并对图像质量主观评分。比较3组间的CTDIvol、SNR、CNR和主观评分。结果肺动脉主干及各叶肺动脉平均CT值A组明显低于C组（F=2．65，P〈0．05），但B组与A、C组间差异无统计学意义（P〉0．05）；背景噪声A组明显高于B、C组（F=16．38，P〈0．001），但B、C组间差异无统计学意义（P〉0．05）；A组SNR和CNR均明显低于B、C两组（F=17．17、19．13，P〈0．001），但B、C组问差异无统计学意义（P〉0．05）。3组间CTDIvol，及图像质量主观评分差异均无统计学意义（P〉0．05）。结论针对非过度肥胖患者，在CTPA成像中，注射稀释低碘浓度对比剂，并联合低管电压扫描和迭代重建算法，可以在保证图像质量的同时，控制辐射剂量水平，具有较好的临床应用价值。临床试验注册北京协和医院，PUMCH．PULMONARYDISEASES2011BA11B17。

Objective To evaluate the feasibility and value of using dilute iodine contrast agent combined with low tube voltage in CT pulmonary angiography （CTPA）. Methods A total of 60 patients with clinically suspected pulmonary embolism were enrolled in this prospective study. All of them were divided into three groups（n = 20） using a table of random numbers method, and then underwent CTPA （group A： 120 kV, auto mA, 350 mgI/ml, FBP algorithm; group B： 100 kV, auto mA,280 mgI/ml, AIDR3D standard algorithm; group C：80 kV, auto mA,245 mgI/ml,A1DR3D strong algorithm）. In these three groups, CT volume dose index （ CTDIvol ） , pulmonary artery enhanced CT values, background noise, signal to noise ratio （SNR）, and the contrast to noise ratio （CNR） in each group were calculated. All of the data and the subjective scores of image quality for each group were compared. Results The average CT value in group A was significantly lower than that in group C （F = 2. 65, P 〈0. 05 ）. However, there was no significant difference between other groups （ P 〉 0.05 ）. The noise in group A was much higher than that in groups B and C （ F = 16. 38, P 〈 0. 001 ）, there was no statistically significant difference between group B and group C （P 〉 0. 05）. Compared with groups B and C, SNR and CNR were lower in group A with statistically significant differences （ F = 17.17, 19. 13, P 〈 0. 001 ）. There was no statistical difference of the CTDIvol and image quality scores among three groups. Conclusions In CTPA, the application of dilute iodine contrast agent combined with low tube voltage and AIDR3D reconstruction algorithm for all except obese patients can decrease radiation dose while meeting the diagnostic requirements of image quality, which has a good clinical application value. Trial registration Peking Union Medical College Hospital, PUMCH-PULMONARY DISEASES 2011BA11B17.