低碘浓度对比剂结合Z-dom及iDose4技术在颈部CT血管造影中的应用

目的：探讨低碘浓度对比剂结合Z轴自动管电流调制（Z-dom）及第四代高级迭代重建（iDose4）技术在颈部CT血管造影（CTA）中的应用价值，以降低对比剂及电离辐射伤害。方法：收集2018 年10月至2019年9月温州医科大学附属第二医院行颈部CTA检查患者100例，随机分成2组：常规组50例，行常规扫描，即120 kV、250 mAs、碘海醇（350 mgI/mL）及滤波反投影法（FBP）重建；低剂量组50例，120 kV、Z-dom自动管电流、碘克沙醇（270 mgI/mL）及iDose4迭代重建。比较2组碘注射量及辐射剂量，在颈总动脉和颈内动脉起始层面进行客观评价，并对图像进行主观评价。结果：碘注射量低剂量组[（16.61±2.87）g]比常规组[（22.82±3.81）g]低（P ＜0.01）；管电流低剂量组[（149.22±70.49）mAs]比常规组（250 mAs）低（P ＜0.01）；低剂量组容积CT剂量指数（CTDIvol）、剂量长度乘积（DLP）及有效剂量（ED）均较常规组低（均P ＜0.01）。2组图像客观评价：低剂量组两层面血管CT值和背景噪声均低于常规组，颈总动脉起始层面信噪比（SNR）、对比噪声比（CNR）均高于常规组（均P ＜0.001）；主观评价：2名医师主观评分Kappa值为0.765，一致性良好，常规组评分为（3.44±0.48）分，低剂量组为（3.60±0.47）分，2组差异无统计学意义（t>1.676，P =0.097），2组图像均可满足诊断需要。结论：低碘浓度对比剂结合Z-dom及iDose4 技术在颈部CTA检查中，其图像质量优于常规组，能够满足诊断需要，同时可降低患者碘注射量及电离辐射剂量。

Application of low iodine concentration contrast agent combined with Z-dom and iDose4 technology in carotid CT angiography

Objective: To explore the value of low iodine contrast agent combined with Z-dom and iDose4 in carotid CT angiography (CTA) to reduce contrast agent and ionizing radiation damage.Methods: A total of 100 patients with CTA examination from the Second Affiliated Hospital of Wenzhou Medical University between January 2018 and September 2019 were randomly divided as the routine group (n=50), with routine scanning, 120 kV, 250 mAs, iohexol (350 mgI/mL) and filtered back projection (FBP) reconstruction, and the low-dose group (n=50), with 120 kV, Z-dom automatic tube current, iodixanol (270 mgI/mL) and iDose4 reconstruction.The iodine injection amount and radiation dose were compared between the two groups. Objective evaluation was performed on the upper edge of the aortic arch and the bifurcation of the carotid artery, followed by subjective evaluation of the images. Results: The amount of iodine injection in the low-dose group was (16.61±2.87)g,lower than that in the routine group (22.82±3.81)g (P<0.001). The tube current in the low-dose group was(149.22±70.49)mAs, lower than that in the routine group (250 mAs) (P<0.001). The CT dose index volume(CTDIvol), dose length product (DLP), and effective dose (ED) of the low-dose group were lower than those of routine group (P<0.001). Objective evaluation of two groups of images showed the CT value of blood vessels and background noise of the two levels in the low-dose group lower than the routine group, and the SNR and CNR of the initial level of the common carotid artery were higher than the routine group (P<0.001).The subjectiveevaluation showed no significant difference (t=-1.676, P=0.097) in the scores of the routine group (3.44±0.48)and the low-dose group (3.60±0.47), both images could meet the diagnostic needs. Conclusion: Low-iodine contrast agent combined with Z-dom and iDose4 technology can reduce the amount of iodine injection and ionizing radiation dose in carotid CT angiography. Its image quality is better than that of the conventional group, though both can meet the diagnostic needs.