采用瞬态饱和转移磁共振成像快速测量脑大分子质子分数
Rapid measurement of brain macromolecular proton fraction with transient saturation transfer MRI.
作者信息
van Gelderen Peter, Jiang Xu, Duyn Jeff H
机构信息
Advanced MRI Section, Laboratory of Functional and Molecular Imaging, National Institutes of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA.
出版信息
Magn Reson Med. 2017 Jun;77(6):2174-2185. doi: 10.1002/mrm.26304. Epub 2016 Jun 25.
PURPOSE
To develop an efficient MRI approach to estimate the nonwater proton fraction (f) in human brain.
METHODS
We implement a brief, efficient magnetization transfer (MT) pulse that selectively saturates the magnetization of the (semi-) solid protons, and monitor the transfer of this saturation to the water protons as a function of delay after saturation.
RESULTS
Analysis of the transient MT effect with two-pool model allowed robust extraction of f at both 3 and 7 T. This required estimating the longitudinal relaxation rate constant (R and R ) for both proton pools, which was achieved with the assumption of uniform R and R across brain tissues. Resulting values of f were approximately 50% higher than reported previously, which is partly attributed to MT-pulse efficiency and R being higher than assumed previously.
CONCLUSION
Experiments performed on human brain in vivo at 3 and 7 T demonstrate the ability of the method to robustly determine f in a scan time of approximately 5 min. Magn Reson Med 77:2174-2185, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
目的
开发一种高效的磁共振成像（MRI）方法来估计人脑的非水质子分数（f）。
方法
我们实施了一个简短、高效的磁化传递（MT）脉冲，该脉冲选择性地使（半）固体质子的磁化饱和，并监测这种饱和向水质子的转移，作为饱和后延迟时间的函数。
结果
用双池模型对瞬态MT效应进行分析，能够在3T和7T场强下可靠地提取f。这需要估计两个质子池的纵向弛豫速率常数（R和R），通过假设脑组织中R和R均匀来实现。得到的f值比先前报道的大约高50%，这部分归因于MT脉冲效率以及R高于先前假设的值。
结论
在3T和7T场强下对人脑进行的体内实验表明，该方法能够在大约5分钟的扫描时间内可靠地测定f。《磁共振医学》77:2174 - 2185, 2017。© 2016国际磁共振医学学会。
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