基于单方向和多方向FSD准备的三维非增强磁共振血管成像在足动脉的应用价值比较

Comparison of 3D non-contrast enhanced foot MR angiography using steady-state free precession with single and multi-directional FSD modules preparation

目的使用基于流动敏感散相(flow-sensitive dephasing,FSD)准备的稳态自由进动(steady-state free precession,SSFP)序列对足动脉进行三维非增强磁共振血管成像(non-contrast enhanced magnetic resonance angiography,NCE-MRA),比较分别在单方向和多方向施加FSD准备模块的图像质量。材料与方法共32名健康志愿者和3例糖尿病患者参与了本项前瞻性研究。在1.5 T磁共振扫描仪上使用心电图(electrocardiograph,ECG)触发的SSFP序列对足动脉实施NCE-MRA,在单方向施加FSD模块和两个方向同时施加FSD模块进行了两次扫描。分别从三个主要动脉节段(足背动脉、足底外侧动脉和足弓动脉)的可诊断节段数、信噪比(signal-to-noise ratio,SNR)、与周围肌肉之间的对比度噪声比(contrast-to-noise ratio,CNR)、血管锐利度和图像质量对这两次扫描进行了评估和比较。结果仅在读出方向上施加FSD模块以及在读出和选层编码两个方向上都施加FSD模块进行的两次SSFP扫描获得的NCE-MRA图像在可诊断动脉节段数、SNR、CNR和血管锐利度这几个指标上没有显著差异(P>0.05)。仅在单方向施加FSD模块采集的NCE-MRA图像质量评分(3.61±0.54)高于在两个方向都施加FSD模块采集的图像质量评分(3.55±0.61)。但是,仅在单方向施加FSD模块采集的NCE-MRA图像中,有些足弓动脉未能完全显示,而在两个方向都施加FSD模块采集的图像中,这些足弓动脉能被很好地勾画。结论基于多方向FSD准备的NCE-MRA成像比基于单方向FSD准备的NCE-MRA能更好地显示足动脉节段。

Objective: To compare the image quality of pedal arteries acquired from three- dimensional (3D) non-contrast enhanced magnetic resonance angiography (NCE-MRA) using steady-state free precession (SSFP) sequence with single directional and multi-directional flow- sensitive dephasing (FSD) modules preparation, respectively. Materials and Methods: A total of 32 healthy volunteers and 3 patients with diabetes prospectively underwent 3D NCE- MRA applying ECG (Electrocardiograph)-triggered SSFP sequence with single directional and two directional FSD modules successively in pedal arteries at a 1.5 T MR scanner. Number of diagnostic arterial segments, signal-to-noise ratio (SNR) of pedal artery, contrast-to-noise ratio (CNR) between pedal artery and surrounding muscle, vessel sharpness, and image quality on a four point score of three main segments (dorsal artery, lateral plantar artery, and pedal arch) were statistically compared for the two techniques. Results: No signi ficant difference existed in number of diagnostic arterial segments, SNR, CNR, and vessel sharpness of NCE-MRA images acquired from SSFP sequence with one FSD module applied in only readout direction and two FSD modules applied in both readout and partition-encoding directions (P>0.05). The image quality scores of NCE-MRA with single directional FSD module was higher than that with two directional FSD modules. However, pedal arch not displayed completely in full length in some images acquired with single directional FSD module was delineated well in images acquired with two directional FSD modules. Conclusions: NCE-MRA using SSFP with multi-directional FSD module could display the pedal arterial segments better than that with only single directional FSD module.