利用椭圆脉冲二阶场（ECLIPSE）对人脑质子磁共振波谱成像进行稳健的外容积抑制
Robust outer volume suppression utilizing elliptical pulsed second order fields (ECLIPSE) for human brain proton MRSI.
作者信息
Kumaragamage Chathura, De Feyter Henk M, Brown Peter, McIntyre Scott, Nixon Terence W, de Graaf Robin A
机构信息
Department of Radiology and Biomedical Imaging, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut.
Department of Biomedical Engineering, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut.
出版信息
Magn Reson Med. 2020 May;83(5):1539-1552. doi: 10.1002/mrm.28047. Epub 2019 Nov 19.
PURPOSE
The robust and reliable utilization of proton magnetic resonance spectroscopic imaging (MRSI) at high fields is hampered by several key technical difficulties, including contamination from extracranial lipids. To that end, this work presents novel lipid suppression sequences for proton MRSI in the human brain utilizing elliptical localization with pulsed second-order fields (ECLIPSE).
METHODS
Two lipid suppression methods were implemented with the ECLIPSE gradient insert. One method is a variable power, 4-pulse sequence optimized to achieve outer volume suppression (OVS) and compared against a standard, 8-slice OVS method. The second ECLIPSE method is implemented as an inversion recovery (IR) sequence with elliptical inner volume selection (IVS) and compared against a global IR method.
RESULTS
The ECLIPSE-OVS sequence provided a 116-fold mean lipid suppression (range, 104-134), whereas an optimized 8-slice OVS sequence achieved 15-fold suppression (range, 13-18). Furthermore, the superior ECLIPSE-OVS suppression was achieved at 30% of the radiofrequency (RF) power required by 8-slice OVS. The ECLIPSE-based IR sequence suppressed skull lipids by 155-fold (range, 122-257), compared to 16-fold suppression (range, 14-19) achieved with IR.
CONCLUSION
OVS and IVS executed with ECLIPSE provide robust and effective lipid suppression at reduced RF power with high immunity to variations in B and T .
目的
高场强下质子磁共振波谱成像（MRSI）的稳健可靠应用受到几个关键技术难题的阻碍，包括来自颅外脂质的污染。为此，本研究提出了一种利用椭圆定位和脉冲二阶场（ECLIPSE）的新型脂质抑制序列，用于人脑质子MRSI。
方法
采用ECLIPSE梯度插入件实现了两种脂质抑制方法。一种方法是可变功率4脉冲序列，优化以实现外容积抑制（OVS），并与标准的8层OVS方法进行比较。第二种ECLIPSE方法实现为具有椭圆内容积选择（IVS）的反转恢复（IR）序列，并与全局IR方法进行比较。
结果
ECLIPSE-OVS序列提供了116倍的平均脂质抑制（范围为104-134），而优化的8层OVS序列实现了15倍的抑制（范围为13-18）。此外，ECLIPSE-OVS在8层OVS所需射频（RF）功率的30%时实现了更高的抑制效果。基于ECLIPSE的IR序列将颅骨脂质抑制了155倍（范围为122-257），相比之下，IR实现的抑制倍数为16倍（范围为14-19）。
结论
通过ECLIPSE执行的OVS和IVS在降低RF功率的情况下提供了稳健有效的脂质抑制，对B和T的变化具有高度抗性。
Zotero 插件