L-LWiDose4技术在新生儿先天性心脏病CT血管成像中的临床应用

目的：探讨低X线辐射剂量及低碘浓度等渗对比剂联合iDose4迭代重建技术（L-LWiDose4）在新生儿先天性心脏病CT血管成像（CTA）中的可行性。方法：前瞻性收集2015年1月至2018年3月温州医科大学附属第二医院育英儿童医院新生儿科需行心脏CTA检查的连续102例患者，随机分为2组，采用不同的扫描方案：常规组（A组）53例，采用100 kVp、100 mAs、碘海醇（350 mg I/mL），重建方式为滤波反投影（FBP）算法；实验组49例，采用80 kVp、80 mAs、碘克沙醇（270 mg I/mL），根据iDose4迭代算法可以得到iDose4-1～iDose4-7 7组图像，选取iDose4-2～iDose4-6 5组图像，分别记为B组、C组、D组、E组、F组。依据新生儿体质量采取不同的对比剂注射剂量并计算碘摄入量。测量主动脉弓、气管分叉水平降主动脉、肺动脉干及主动脉弓层面两侧胸大肌和竖脊肌CT值，测量气管分叉层面周围空气CT值的标准差（SD），记为背景噪声，计算信噪比（SNR）和对比噪声比（CNR），并对图像质量进行主观评价。记录容积CT剂量指数（CTDIvol）和剂量长度乘积（DLP），并计算有效剂量（ED）和体型特异性剂量评估（SSDE）。以手术或心导管造影为“金标准”，统计并比较各组CTA检查的诊断符合率。结果：实验组CTDIvol、SSDE、DLP、ED较常规组分别降低了57.08%、56.62%、58.31%、56.97%（P＜0.05）。常规组、实验组对比剂碘摄入量分别为（1.83±1.27）g和（1.61± 1.36）g，差异有统计学意义（P＜0.05）。B组、F组图像客观评价不及A组、C组、D组、E组（P＜0.05）。A组、D组、E组图像主观评价差异无统计学意义。常规组、实验各组诊断符合率分别为98.6%、81.6%、87.7%、97.9%、97.9%、96.9%，差异无统计学意义（P＞0.05）。结论：80 kVp、80 mAs、碘克沙醇（270 mg I/mL）联合iDose4迭代重建技术新生儿先天性心脏病CTA检查，在降低患者的电离辐射剂量和对比剂碘剂量的同时，其图像质量能够满足临床诊断需要。

Clinical application of CT angiography of neonatal congenital heart disease by using low radiation and isotonic contrast agents with low iodine doses combined with iDose4 iterative reconstruction technique

Objective: To evaluate the feasibility of CT angiography of neonatal congenital heart disease by using low radiation and isotonic contrast agents with low iodine doses combined with iDose4 iterative reconstruction technique. Methods: Prospectively, a total of 102 continuous patients from department of neonatology of our hospital between January 2015 and March 2018 who needed CT angiography of heart were divided into 2 groups randomly. Different scan protocols were adopted. Routine group (group A) included 53 patients using 100 kVp, 100 mAs, Iohexol (350 mg I/mL) and filtered back projection algorithm. Experimental group included 49 patients using 80 kVp, 80 mAs, Iodixanol (270 mg I/mL) and seven groups of images were acquired according to iDose4 iterative reconstruction algorithm (iDose4-1-iDose4-7), of which 5 groups (iDose4-2-iDose4-6) were selected and recorded as group B, group C, group D, group E, and group F. Individualized injections were given according to the weight of newborns and their iodine intake was calculated. CT value of aortic arch, descending aorta at the level of tracheal bifurcation, pulmonary trunk, pectoralis major and erector spinae on both sides at the level of aortic arch were measured. The standard deviation (SD) of CT value of the air around at the tracheal bifurcation level was recorded as background noise, and signal to noise ratio (SNR) and contrast to noise ratio (CNR) were calculated, and the quality of images was evaluated subjectively. Volume CT dose index (CTDIvol) and dose-length-product (DLP) were recorded, and the effective dose (ED) and size-specific dose estimate (SSDE) were calculated. The diagnostic coincidence rate for CTA examinations of these six groups was calculated and compared with the surgery or cardiac catheterization examination as the “gold standard”. Results: Compared with routine group, CTDIvol, SSDE, DLP, ED of experimental group descended by 57.08%, 56.62%, 58.31%, 56.97%, respectively (P<0.05). The iodine intake of experimental group and routine group was (1.83±1.27)g, (1.61±1.36)g respectively, with significant statistical difference (t=2.124, P<0.05). The objective evaluation of group B and group F was not as good as that of group A, group C, group D and group E (P<0.05). Subjective evaluation of group A and group E was better than the other groups. Subjective evaluation of group C and group D was better than group B and group F. The diagnostic coincidence rate of the six groups was 98.6%, 81.6%, 87.7%, 97.9%, 97.9%, 96.9%, respectively (P>0.05). Conclusion: Using 80 kVp, 80 mAs and Iodixanol (270 mg I/mL) combined with iDose4 iterative reconstruction technique for CT angiography of neonatal congenital heart disease, the image quality could meet the requirement for clinical diagnosis, and the radiation dose and the iodine dose of contrast medium could be lowered.