Fast quantitative MRI using controlled saturation magnetization transfer.
Fast quantitative MRI using controlled saturation magnetization transfer.
复制标题
使用受控饱和磁化转移的快速定量MRI。
DOI：
10.1002/mrm.27442
复制
发表时间：
2019-03
影响因子：
3.3
通讯作者：
Hajnal JV
中科院分区：
文献类型：
--
作者：
A G Teixeira RP;Malik SJ;Hajnal JV
本研究证明了磁化转移（MT）效应直接影响弛豫测量，并开发了一个框架，使单池模型在2池MT系统中有效。本文提出了一个理论框架，在该框架中，如果RMS射频磁场（{\text{B}}_{1}^{{\text{RMS}}}}）在所有测量中保持固定，则2‐pool MT系统有效地表现为单个池。提出了一种利用多波段射频脉冲实现可控饱和磁化转移的实用方法。数值验证、幻影验证和体内验证直接比较了在正确的单池假设下的稳态（SS）估计方法，这些方法在精度上而不是准确性上应该有所不同。数值模拟预测，从MT模型生成的数据中获得的单池估计值对于不同的SS估计方法是不一致的，并且预计会系统性地低估T2。在提出的CSMT方法下，这两种效应都不会发生。模拟实验和体内实验都证实了数值预测。实验数据强调，即使使用相同的松弛测量方法，如果不使用CSMT方法，则根据使用翻转角（FAs）和TRs的组合获得不同的估计。利用CSMT，得到了T1和T2的稳定测量值。测量的T1)依赖于{\text{B}}_{1}^{{\text{rms}}}}，因此这是一个需要指定的重要参数。这项工作表明，传统的单池弛缓测量在人体研究中非常有效，但由于MT效应，在生物组织中导致参数估计不可靠。所提出的CSMT框架被证明允许单池假设是有效的，从而能够进行可靠和有效的定量成像。
This study demonstrates magnetization transfer (MT) effects directly affect relaxometry measurements and develops a framework that allows single‐pool models to be valid in 2‐pool MT systems. A theoretical framework is developed in which a 2‐pool MT system effectively behaves as a single‐pool if the RMS RF magnetic field ({\text{B}}_{1}^{{{\text{rms}}}}) is kept fixed across all measurements. A practical method for achieving controlled saturation magnetization transfer (CSMT) using multiband RF pulses is proposed. Numerical, Phantom, and in vivo validations were performed directly comparing steady state (SS) estimation approaches that under correct single‐pool assumptions would be expected to vary in precision but not accuracy. Numerical simulations predict single‐pool estimates obtained from MT model generated data are not consistent for different SS estimation methods, and a systematic underestimation of T2 is expected. Neither effect occurs under the proposed CSMT approach. Both phantom and in vivo experiments corroborate the numerical predictions. Experimental data highlights that even when using the same relaxometry method, different estimates are obtained depending on which combination of flip angles (FAs) and TRs are used if the CSMT approach is not used. Using CSMT, stable measurements of both T1 and T2 are obtained. The measured T1 ) depends on {\text{B}}_{1}^{{{\text{rms}}}}, which is therefore an important parameter to specify. This work demonstrates that conventional single pool relaxometry, which is highly efficient for human studies, results in unreliable parameter estimates in biological tissues because of MT effects. The proposed CSMT framework is shown to allow single‐pool assumptions to be valid, enabling reliable and efficient quantitative imaging to be performed.
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影响因子：
3.3
作者：
Hurley, Samuel A.;Yarnykh, Vasily L.;Samsonov, Alexey A.
通讯作者：
Samsonov, Alexey A.
影响因子：
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作者：
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影响因子：
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作者：
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通讯作者：
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影响因子：
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作者：
Girard, Olivier M.;Prevost, Valentin H.;Duhamel, Guillaume
通讯作者：
Duhamel, Guillaume