Investigating exchange and multicomponent relaxation in fully-balanced steady-state free precession imagaing
Investigating exchange and multicomponent relaxation in fully-balanced steady-state free precession imagaing
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DOI：
10.1002/jmri.21079
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发表时间：
2008-06-01
影响因子：
4.4
通讯作者：
Jones, Derek K.
中科院分区：
文献类型：
--
作者：
Deoni, Sean C. L.;Rutt, Brian K.;Jones, Derek K.
目的：研究化学交换和多组分弛豫对快速T-2映射方法、DESPOT 2（T-2的驱动平衡单脉冲观测）及其所依据的稳态自由进动（SSFP）序列的影响。虽然能够快速T-2测定，该方法隐含的假设是单组分弛豫。在许多生物组织（如白色和灰质），它是公认的T-2衰减曲线是更准确地描述了一个以上的弛豫species.Materials和方法的总和：交换的影响，首先纳入一般SSFP磁化表达式和测量SSFP信号的影响，使用布洛赫-麦康奈尔模拟研究。结果：模拟结果表明，在通常的成像条件下，当重复时间远小于T-2时，多组分SSFP信号可以表示为各组分信号的线性和。使用奶油进行成像实验表明，与所提出的理论强一致。最后，使用牛奶奶油模型，我们证明了量化的多组分松弛从多角度SSFP数据的第一次，显示良好的协议与参考自旋回波values.Conclusion：SSFP和DESPOT 2可能提供一种新的方法调查多组分系统，如人脑，和疾病的过程，如多发性硬化症。
Purpose: To investigate the effect of chemical exchange and multicomponent relaxation on the rapid T-2, mapping method, DESPOT2 (driven equilibrium single pulse observation of T-2) and the steady-state free precession (SSFP) sequence upon which it is based. Although capable of rapid T-2 determination, an assumption implicit of the method is single-component relaxation. In many biological tissues (such as white and gray matter), it is well established that the T-2 decay curve is more accurately described by the summation of more than one relaxation species.Materials and Methods: The effects of exchange were first incorporated into the general SSFP magnetization expressions and its effect on the measured SSFP signal investigated using Bloch-McConnell simulations. Corresponding imaging experiments were performed to support the presented theory.Results: Simulations show the measured multicomponent SSFP signal maybe expressed as a linear summation of signal from each species under usual imaging conditions where the repetition time is much less than T-2. Imaging experiments performed using dairy cream demonstrate strong agreement with the presented theory. Finally, using a dairy cream model, we demonstrate quantification of multicomponent relaxation from multiangle SSFP data for the first time, showing good agreement with reference spin-echo values.Conclusion: SSFP and DESPOT2 may provide a new method for investigating multicomponent systems, such as human brain, and disease processes, such as multiple sclerosis.