双时相3D SSFP 成像技术在先天性心脏病诊断中的应用初探

目的：探讨双时相三维稳态进动快速成像序列（3DSSFP）对先天心脏病的诊断价值。方法：60例平均心率108次／分的先天性心脏病患儿行收缩末期和舒张中晚期的双时相3D SSFP成像，对图像质量及对比噪声比进行分析比较。结果：心电触发收缩期延迟时间为180～300ms，平均（235．41士35．59）ms；舒张期延迟时间为384～550ms，平均（443．77土50．81）ms。3DSSFP收缩期图像上显示心内结构及肺静脉、上下腔静脉的清晰度优于舒张期，两者间图像质量的差异有统计学意义（P〈o．05）。舒张期图像上对无狭窄主动脉及肺动脉的显示清晰度高于收缩期，但两者间差异无统计学意义（P〉o．05）。收缩期图像上心内结构的对比噪声比（CNR）均高于舒张期，且两者比较差异有统计学意义（P〈0．05）。上腔静脉及下腔静脉在收缩期图像上的CNR均高于舒张期，但仅下腔静脉CNR的差异有统计学意义（P〈0．05）；主动脉和肺总动脉则在舒张期图像上的CNR高于收缩期，但两者比较差异无统计学意义（P〉0．05）。伴有肺动脉辫及辫下狭窄的肺动脉分支在收缩期的显示率（39．1％）明显低于舒张期（73．9％）。结论：双时相3DSSFP综合利用收缩期和舒张期不同时相的成像优势，能更准确地诊断先天性心脏病患儿的心内及心外大血管结构的畸形。

Preliminary study of three dimensional dual-phase steady state free precession imaging technique in the diagnosis of congenital Children s Medical heart diseases

Objective：To evaluate the value of MRI dual phase three dimensional steady state free precession （dual- phase 3D SSFP） sequence in the diagnosis of congenital heart disease iCHD）. Methods;60 pediatric patients of CHD with the average heart rate as 108 beats/min underwent MRI dual-phase 3D SSFP sequence,the acquired images were at the end systolic phase and mid-late diastolic phase. The image quality and contrast-to-noise ratio （CNR） were analyzed and com- pared. Results.. The ECG trigger delay time was 180 ～300ms [mean= （235.41 ± 35. 59） ms] in systole and 384 ～ 550ms [m=（443.77 q±50.81）ms] in diastole. The image qualities of intra-cardiac structures, pulmonary veins, superior and inferior vena cava in 3D SSFP systole were significantly better than that in diastole, with statistical difference （P〈0.05）. However, the distinctness of aorta with no stenosis and main pulmonary artery was better in diastole compared with that of systole, yet with no statistical difference （P〉O. 05）. The CNR of intra-cardiac structures was significantly higher in 3D SSFP systo- le than in diastole,with statistic difference （P〈0.05）. The CNR of SVC and IVC was higher in systole,but only the CNR of 1VC showed statistical difference （P〈0.05）. The CNR of aorta and main pulmonary artery was lower in systole than in diastole,but there was no statistieal difference （P〉0.05）. In patients with pulmonary stenosis and subvalvuular pulmonary stenosis,the percentage of visibility of pulmonary artery branches in systole was only 39. 1%, but was higher in diastole （73.9 %）. Conclusion; Dual-phase 3D SSFP sequence had the advantages of showing images in systole and diastole and ulti- mately can provide more accurate diagnosis of intra-/ extra-cardiac great vessel abnormalities in pediatric patients with CHD.