MR冠脉成像靶容积与全心扫描方法的优势探讨

目的探讨自由呼吸导航三维采样磁共振冠脉成像靶容积和全心扫描方法的特点与优势。方法对21例志愿者进行1.5T自由呼吸磁共振冠脉成像扫描,包括右冠状动脉和左旋支的靶容积及全心扫描,两种方法的基本扫描参数相同,扫描完成进行后处理,得到靶容积和全心扫描的右冠状动脉及左旋支图像,对右冠脉及左旋支各节段的图像质量进行评分,测量右冠脉及左旋支的长度,观察右冠脉后降支的显示情况,评价两种方法的特点和优势。结果全心扫描的时间明显长于单次冠脉靶容积扫描的时间,两种方法在显示右冠状动脉和左冠脉旋支的长度上无明显差别,对于右冠状动脉后降支的显示而言,全心扫描较靶容积扫描具有明显的优势,在图像质量方面,靶容积扫描优于全心扫描方法。结论自由呼吸导航三维采样磁共振冠脉成像靶容积和全心扫描方法具有各自的优势,在临床中可根据具体情况进行选择应用或联合应用。

Comparison of free-breathing 3D coronary MR angiography using the volume-targeted and whole-heart methods

Objective：To make a comparison between the RCA-and LCX-targeted and whole-heart 3D coronary MR angiography using a T2-prepared SSFP sequence with real-time navigation.Materials and Methods：Twenty-one volunteers underwent free-breathing navigator-gated 3D coronary MR angiography,including both RCA-and LCX-targeted MR angiography and whole-heart coronary MR angiography with comparable imaging parameters on a 1.5 T whole-body MR system.We compared the acquisition time,the overall image quality of each segments of RCA and LCX,measured the length of the RCA and LCX,and assessed the posterior descending arterial branches of the RCA obtained with the volume-targeted and whole-heart approaches.Statistical analysis was performed with P value less than 0.05 considered signifi cant.Results：The imaging time required for whole-heart acquisition was signifi cantly longer than the RCA-and LCX-targeted acquisition （whole-heart,9.82±2.62 vs volume-targeted,4.31±0.87 minutes;P0.05）.The depicted length of the coronary arteries were not significantly different between the whole-heart and volume-targeted coronary MR angiography （whole-heart,RCA/LCX=12.2±3.4/7.81±1.5 vs volume-targeted,RCA/LCX= 11.9±3.2/7.59±1.2 cm;P0.05）.Whole-heart method had advantages for the visualization of posterior descending artery branches derived from the RCA.However,volume-targeted method yields higher vessel sharpness and overall image quality in comparison with whole-heart acquisition （volume-targeted,RCA/LCX = 4.33±0.97/4.29±0.89 vs whole-heart,RCA/LCX= 3.84±1.03/3.59±0.86;P0.05）.Conclusion：Volume-targeted and whole-heart navigator-assisted coronary MR angiography had its own advantages respectively,and the combined use of the two methods could be potentially helpful for clinical applications.