Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands.
Magn Reson Med. 2012 Sep;68(3):662-70. doi: 10.1002/mrm.23288. Epub 2011 Dec 12.
Proton MR spectroscopic imaging of the human brain at ultra-high field (≥7 T) is challenging due to increased radio frequency power deposition, increased magnetic field B(0) inhomogeneity, and increased radio frequency magnetic field inhomogeneity. In addition, especially for multislice sequences, these effects directly inhibit the potential gains of higher magnetic field and can even cause a reduction in data quality. However, recent developments in dynamic B(0) magnetic field shimming and dynamic multitransmit radio frequency control allow for new acquisition strategies. Therefore, in this work, slice-by-slice B(0) and B(1) shimming was developed to optimize both B(0) magnetic field homogeneity and nutation angle over a large portion of the brain. Together with a low-power water and lipid suppression sequence and pulse-acquire spectroscopic imaging, a multislice MR spectroscopic imaging sequence is shown to be feasible at 7 T. This now allows for multislice metabolic imaging of the human brain with high sensitivity and high chemical shift resolution at ultra-high field.
由于射频功率沉积增加、磁场 B(0)不均匀性增加和射频磁场不均匀性增加，在超高场（≥7T）下进行人体大脑的质子磁共振波谱成像是具有挑战性的。此外，特别是对于多切片序列，这些效应直接抑制了更高磁场的潜在增益，甚至可能导致数据质量下降。然而，动态 B(0)磁场匀场和动态多发射射频控制的最新发展允许采用新的采集策略。因此，在这项工作中，开发了逐片 B(0)和 B(1)匀场，以优化大脑大部分区域的 B(0)磁场均匀性和旋进角。结合低功率水和脂质抑制序列和脉冲采集波谱成像，在 7T 下展示了一种多切片磁共振波谱成像序列的可行性。这使得在超高场下进行高灵敏度和高化学位移分辨率的人类大脑多切片代谢成像成为可能。
