第3代双源CT非线性融合技术在低对比剂用量及低注射流率注射条件下在腹主动脉成像中的应用研究

Application of non-linear blending technique in abdominal aortic angiography involving novel injection protocol with reduced contrast medium dose and low flow rate

摘要:

目的：探讨第3代双源CT非线性融合技术（non-linear blending，NLB）在低对比剂总量及低注射流率个性化注射条件下提高腹主动脉CT血管成像（CT angiography，CTA）图像质量的可行性。方法：收集30例拟行双能量腹主动脉CTA扫描的患者，使用70/Sn150kVp管电压结合CARE Dose 4D智能管电流调节技术，根据患者体质量乘以0.5计算造影剂总量，根据造影剂总量除以检查时间（扫描时间及达到触发阈值后的延迟时间之和）计算注射流速。重建NLB图像及融合系数为0.5的常规线性融合（linear blending，LB）图像。通过配对t检验比较两组图像腹主动脉及其主要分支血管起始部CT值、信噪比（signal to noise ratio，SNR）、对比噪声比（contrast to noise ratio，CNR）等。采用Mann-Whitney U检验比较两组图像主观质量评分，通过Kappa检验对两组图像主观质量评分做一致性分析。结果：患者平均有效辐射剂量为（4.80±0.77） mSv，平均碘摄入量为（12.30±1.71） g，平均对比剂用量为（35.30±4.91） mL，平均注射流速为（3.30±0.47） mL/s。NLB组各组血管CT值、SNR及CNR均较LB组大幅度提高（P<0.05），而NLB组血管层面背部肌肉平均CT值和SD值与LB组相比，差异无统计学意义（P>0.05）。2组图像评价结果一致性较好（?资=0.618，P<0.05），NLB组图像主观评分高于LB组，主观评分提高0.55分（P<0.05）。结论：第3代双源CT的NLB技术在低对比剂总量及低注射流率的个体化扫描条件下可以大幅度提高腹主动脉CTA的图像质量。

Abstract:

Objective：To investigate the feasibility of enhancing image quality of abdominal aorta Computed Tomography Angiography （CTA） under low contrast agent and individualized injection of low injection rate with non-linear blending（NLB） of third-generation dual-resource CT device. Methods：A total of 30 patients who were likely to undergo dual-energy abdominal aorta CTA were enrolled. The third-generation dual-source CT device with a tube voltage at 70/sn150 kVp combined with intelligent tube current adjustment technology of CARE Dose 4D was used. The dose of contrast medium was obtained in accordance with patients’ weight plus 0.5，and then the injection velocity was defined by contrast agent/examining time（scanning time + delay time after achieving the trigger threshold value）. NLB image and regular linear blending（LB） with a fusion coefficient of 0.5 were re-constructed. Images’ CT values，signal to noise ratio（SNR） and contrast to noise ratio（CNR） on abdominal aorta and initial part of its main branches in two groups were evaluated by using paired t-test. Subjective quality score of images in two group was compared via Mann-Whitney U test and consistency of the score was analyzed by Kappa test. Results：The average effective radiation dose was （4.80±0.77） mSv，the average iodine intake was （12.30±1.71） g，the average contrast volume was （35.3±4.91） mL，and the average injection velocity was （3.30±0.47） mL/s. Vascular CT value，SNR and CNR in the NLB group were significantly increased than those in LB group（P<0.05）. Average CT value and SD value of muscles at the back of chest in two groups had no statistically significant difference（P>0.05）. Subjective score of images in two groups had good consistency（?资=0.618，P<0.05），and it in the NLB group was higher than that in the LB group，with an improvement of 0.55（P<0.05）. Conclusion：NLB of third-generation dual-source CT device under low contrast agent and individualized injection of low injec－tion rate can significantly improve the image quality of abdominal aorta CTA.