双源CT Flash扫描在心血管源性气道狭窄患儿诊断中的临床应用

Application of flash spiral acquisition by dual-source CT in children with cardiovascular airway constriction

目的探讨双源CT Flash扫描模式在诊断先天性心脏病(先心病)引起气道狭窄病变中的应用价值。方法回顾性收集2013年1月至2015年12月行双源CT Flash扫描,经心脏大血管CTA结果诊断为心脏大血管直接压迫引起的气道狭窄患儿99例。其中男40例,女59例,1个月~16岁,平均22个月,平均体质量(10±7.7)kg。根据机器自动生成的剂量长度乘积(DLP),计算有效辐射剂量(ED)。由两名放射科医生采用5分法对图像质量进行总体评估。气管狭窄诊断标准指支气管管腔口径小于正常支气管管腔口径,利用多平面重组(MPR)及曲面重组(VR)图像准确显示狭窄段气道周围的解剖结构关系,明确造成气道狭窄的心外大血管畸形的责任病灶。按照引起小儿心血管源性气道狭窄的不同血管畸形类型进行归纳总结。同时,在肺窗和最小密度投影(Min IP)上观察患儿肺内继发病变的特点。结果 99例患儿平均DLP(7.32±6.19)m Gy·cm,平均ED(0.39±0.20)m Sv。图像质量均满足诊断要求;两名放射科医师对图像质量的总体评价具有较高一致性(K=0.754,P<0.05)。各年龄段心血管源性气道狭窄患儿中,肺部病变发生率呈随年龄增加而降低的趋势(Z=-3.83,P<0.001)。99例共计104处狭窄被诊断为心血管源性气道狭窄,在造成气道狭窄的心血管畸形中,因肺动脉高压引起38例(36.5%)、主动脉缩窄引起32例(30.8%)、右位主动脉弓引起14例(13.5%)、无名动脉压迫12例(11.5%)、肺动脉吊带6例(5.8%)、双主动脉弓1例(1.0%)、左房大1例(1.0%)。并发肺内病变,包括肺磨玻璃样变36例,肺实变19例,肺不张7例,肺气肿66例。不同类型先心病引起的气道狭窄部位不同,差异有统计学意义(P<0.001)。其中先心病引起的气道狭窄以发生于Ⅲ段,即左主支气管较多。结论双源CT Flash一站式扫描能够同时对心血管和气管支气管情况准确诊断,为临床诊治提供依据。

Objective To explore the application of flash spiral acquisition by dual-source CT in the diagnosis of congenital heart disease complicated with cardiovascular airway constriction. Methods Children suspected with cardiovascular airway compression underwent flash spiral acquisition by dual-source CT during Jan. 2013 and Dec. 2015,and 99 children were finally included in this study,including 40 males and 59 females. The mean age was 22 months and mean body weight was（ 10 ± 7. 7） kg. The dose length product（ DLP） was recorded to calculate effective dose（ ED）. Images were analyzed by two experienced radiologists using a 5-grade scoring system subjectively with post-processing technique. The diagnostic criteria were adopted to determine airway constriction. Multiple planar reformation（ MPR） and volume rendering（ VR） were used to showthe anatomic structures around the narrowsegment,and to define the responsible anomalies and location of the airway constriction. The characteristics of pulmonary lesions were observed in lung windowand minimum intensity projection（ Min IP）. Results The average DLP was（ 7. 32 ± 6. 19） m Gy ·cm,and average ED was（ 0. 39 ± 0. 20） m Sv. All images were diagnosable. The two radiologists made good agreement（ K= 0. 754,P〈0. 05）. With different age groups,the younger the patients,the higher proportion of cardiovascular airway constriction and pulmonary anomalies（ Z =-3. 83,P〈0. 001）. Of all 99 children,a total of 104 constrictions were diagnosed as tracheobronchial compression caused by vascular abnormalities,including pulmonary arterial hypertension in 38 cases（ 36. 5%）,coarctation of aorta in 32 cases（ 30. 8%）,right-sided aortic arch in 14 cases（ 13. 5%）,innominate artery tracheal compression in 12 cases（ 11. 5%）,pulmonary artery sling in 6 cases（ 5. 8%）,double aortic arch in 1 case（ 1. 0%） and left atrial enlargement in 1 case（ 1. 0%）. Secondary pulmonary lesions were also detected,including ground glass opacity in 36 cases,consolidation in 19 cases,emphysema in 66 cases and post-obstructive pulmonary atelectasis in 7 cases. The difference between the different types of primary heart diseases and the locations of the airway constriction was statistically significant（ P〈0. 001）. Airway constrictions caused by congenital heart disease were most likely to occur on the left main bronchus. Conclusion Flash spiral acquisition by dual-source CT can diagnose congenital heart disease with airway compression simultaneously,and provide information for clinical diagnosis and treatment.