Esmaeili Morteza, Bathen Tone F, Rosen Bruce R, Andronesi Ovidiu C
Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA.
Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Trondheim, Norway.
Magn Reson Med. 2017 Feb;77(2):490-497. doi: 10.1002/mrm.26115. Epub 2016 Feb 2.
Large lipid and water signals in MR spectroscopic imaging (MRSI) complicate brain metabolite quantification. In this study, we combined adiabatic hypergeometric dual-band (HGDB) lipid and water suppression with gradient offset independent adiabatic (GOIA) spin echo to improve three-dimensional (3D) MRSI of the entire brain.
3D MRSI was acquired at 3T with a 32-channel coil. HGDB pulses were used before excitation and during echo time. A brain slab was selected with GOIA-W(16,4) pulses, weighted phase encoded stack of spirals, and real-time motion/shim correction. HGDB alone or in combination with OVS and MEGA (MEscher-GArwood) was compared with OVS only and no suppression.
The combined HGDB pulses suppressed lipids to 2%-3% of their full unsuppressed signal. The HGDB lipid suppression was on average 5 times better than OVS suppression. HGDB+MEGA provided 30% more suppression compared with a previously described HGDB+OVS scheme. The number of voxels with good metabolic fits was significantly larger in the HGDB data (91%-94%) compared with the OVS data (59%-80%).
HGDB pulses provided efficient lipid and water suppression for full brain 3D MRSI. The HGDB suppression is superior to traditional OVS, and it can be combined with adiabatic spin echo to provide a sequence that is robust to B inhomogeneity. Magn Reson Med 77:490-497, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
磁共振波谱成像（MRSI）中较大的脂质和水信号使脑代谢物定量变得复杂。在本研究中，我们将绝热超几何双频（HGDB）脂质和水抑制与梯度偏移无关绝热（GOIA）自旋回波相结合，以改善全脑的三维（3D）MRSI。
使用32通道线圈在3T下采集3D MRSI。在激发前和回波时间期间使用HGDB脉冲。通过GOIA-W(16,4)脉冲、加权相位编码螺旋堆叠和实时运动/匀场校正选择脑层面。将单独的HGDB或与OVS和MEGA（Mescher-Garwood）联合使用的情况与仅使用OVS和不进行抑制的情况进行比较。
联合HGDB脉冲将脂质抑制至其完全未抑制信号的2%-3%。HGDB脂质抑制平均比OVS抑制好5倍。与先前描述的HGDB+OVS方案相比，HGDB+MEGA提供了多30%的抑制。与OVS数据（59%-80%）相比，HGDB数据中具有良好代谢拟合的体素数量显著更多（91%-94%）。
HGDB脉冲为全脑3D MRSI提供了有效的脂质和水抑制。HGDB抑制优于传统的OVS，并且它可以与绝热自旋回波相结合，以提供对B不均匀性具有鲁棒性的序列。《磁共振医学》77:490-497, 2017。© 2016国际磁共振医学学会。
