Ribot Emeline J, Wecker Didier, Trotier Aurélien J, Dallaudière Benjamin, Lefrançois William, Thiaudière Eric, Franconi Jean-Michel, Miraux Sylvain
Centre de Résonance Magnétique des Systèmes Biologiques, UMR 5536, CNRS/University Bordeaux, Bordeaux, France.
Bruker Biospin MRI GMBH, Ettlingen, Germany.
PLoS One. 2015 Oct 1;10(10):e0139249. doi: 10.1371/journal.pone.0139249. eCollection 2015.
The purpose of this paper is to develop an easy method to generate both fat signal and banding artifact free 3D balanced Steady State Free Precession (bSSFP) images at high magnetic field.
In order to suppress fat signal and bSSFP banding artifacts, two or four images were acquired with the excitation frequency of the water-selective binomial radiofrequency pulse set On Resonance or shifted by a maximum of 3/4TR. Mice and human volunteers were imaged at 7 T and 3 T, respectively to perform whole-body and musculoskeletal imaging. "Sum-Of-Square" reconstruction was performed and combined or not with parallel imaging.
The frequency selectivity of 1-2-3-2-1 or 1-3-3-1 binomial pulses was preserved after (3/4TR) frequency shifting. Consequently, whole body small animal 3D imaging was performed at 7 T and enabled visualization of small structures within adipose tissue like lymph nodes. In parallel, this method allowed 3D musculoskeletal imaging in humans with high spatial resolution at 3 T. The combination with parallel imaging allowed the acquisition of knee images with ~500 μm resolution images in less than 2 min. In addition, ankles, full head coverage and legs of volunteers were imaged, demonstrating the possible application of the method also for large FOV.
In conclusion, this robust method can be applied in small animals and humans at high magnetic fields. The high SNR and tissue contrast obtained in short acquisition times allows to prescribe bSSFP sequence for several preclinical and clinical applications.
本文的目的是开发一种简便方法，以在高磁场下生成无脂肪信号和带状伪影的三维稳态自由进动（bSSFP）图像。
为了抑制脂肪信号和bSSFP带状伪影，采用水选择性二项式射频脉冲，以共振激发频率或最多偏移3/4TR的频率采集两幅或四幅图像。分别在7T和3T磁场下对小鼠和人类志愿者进行成像，以进行全身和肌肉骨骼成像。采用“平方和”重建，并结合或不结合并行成像。
1-2-3-2-1或1-3-3-1二项式脉冲在（3/4TR）频率偏移后仍保持频率选择性。因此，在7T磁场下对全身小动物进行了三维成像，能够可视化脂肪组织内的小结构，如淋巴结。同时，该方法允许在3T磁场下对人类进行具有高空间分辨率的三维肌肉骨骼成像。与并行成像相结合，能够在不到2分钟的时间内采集分辨率约为500μm的膝关节图像。此外，还对志愿者的脚踝、全脑覆盖区域和腿部进行了成像，证明了该方法在大视野成像中的应用潜力。
总之，这种稳健的方法可应用于高磁场下的小动物和人类。在短采集时间内获得的高信噪比和组织对比度，使得bSSFP序列可用于多种临床前和临床应用。
