High-resolution creatine mapping of mouse brain at 11.7 T using non-steady-state chemical exchange saturation transfer
High-resolution creatine mapping of mouse brain at 11.7 T using non-steady-state chemical exchange saturation transfer
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DOI：
10.1002/nbm.4168
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发表时间：
2019-08-28
影响因子：
2.9
通讯作者：
Xu, Jiadi
中科院分区：
文献类型：
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作者：
Chen, Lin;Wei, Zhiliang;Xu, Jiadi
本研究旨在优化存在强磁化传递对比（MTC）的11.7 T小鼠大脑肌酸化学交换饱和转移加权（CrCESTw）信号的采集方案，并进一步开发利用非稳态（NSS）采集方案量化CrCESTw信号的多项式和洛伦兹线形拟合（PLOF）方法。对交联牛血清白蛋白 (BSA) 的 Cr 模型以及小鼠大脑的研究表明，通过 MTC 池的旋转框架弛豫时间而不是稳态饱和时间确定的短饱和时间即可达到最大 CrCESTw 信号。对于具有 20% 交联 BSA 的 Cr 和体内应用，最大信号的饱和功率约为 1-1.5 μT，但发现 2 μT 对于信号稳定性最实用。对于强MTC干扰的CrCEST采集，最佳饱和功率和长度与单独Cr解的完全不同。通过结合强 MTC 池，使用 R-1 rho 理论可以很好地解释这一观察结果。最后，使用 PLOF 方法结合 NSS CEST 采集和低温线圈获得了小鼠大脑的高分辨率 Cr 图。通过 CEST 获得的 Cr 图显示，除有脑脊液的区域外，整个小鼠大脑的强度均一。
The current study aims to optimize the acquisition scheme for the creatine chemical exchange saturation transfer weighted (CrCESTw) signal on mouse brain at 11.7 T, in which a strong magnetization transfer contrast (MTC) is present, and to further develop the polynomial and Lorentzian line-shape fitting (PLOF) method for quantifying CrCESTw signal with a non-steady-state (NSS) acquisition scheme. Studies on a Cr phantom with cross-linked bovine serum albumin (BSA) as well as on mouse brain demonstrated that the maximum CrCESTw signal was reached with a short saturation time determined by the rotating frame relaxation time of the MTC pool instead of the steady-state saturation. The saturation power for the maximal signal was around 1-1.5 mu T for Cr with 20% cross-linked BSA and in vivo applications, but 2 mu T was found to be most practical for signal stability. For the CrCEST acquisition with strong MTC interference, the optimal saturation power and length are completely different from those on Cr solution alone. This observation could be explained well using R-1 rho theory by incorporating the strong MTC pool. Finally, a high-resolution Cr map was obtained on mouse brain using the PLOF method with the NSS CEST acquisition and a cryogenic coil. The Cr map obtained by CEST showed homogenous intensity across the mouse brain except for regions with cerebrospinal fluid.