A comparison between equations describing in vivo MT:: The effects of noise and sequence parameters
A comparison between equations describing in vivo MT:: The effects of noise and sequence parameters
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DOI：
10.1016/j.jmr.2007.12.012
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发表时间：
2008-04-01
影响因子：
2.2
通讯作者：
Barker, Gareth J.
中科院分区：
文献类型：
--
作者：
Cercignani, Mara;Barker, Gareth J.
磁化传递（MT）的定量模型允许估计组织的物理特性，这些物理特性被认为反映了髓鞘形成，因此可能对临床应用有用。虽然描述连续波饱和下的双池系统的模型已经有二十年了，将这样的模型推广到脉冲MT，并因此推广到体内应用，并不是简单的，并且直到最近才提出了一系列预测脉冲MT实验结果的方程。两个资源库模型的这些解决方案基于不同的假设，涉及不同程度的复杂性，因此其各自的优势和局限性并不总是显而易见的。本文对三种不同的信号方程进行了比较。在回顾了它们背后的理论之后，在可变的实验条件下使用数值模拟研究了它们的准确度和精度，例如采集序列和SNR的T-1加权程度，并使用体内数据测试了数值结果的一致性。我们表明，虽然在最小的T-1加权，高信噪比，和大占空比的条件下，这三个方程的解决方案是一致的，他们有不同的容忍偏差的基本假设背后的发展，这应该考虑到在设计一个定量MT协议。(c)2008年爱思唯尔公司All rights reserved.
Quantitative models of magnetization transfer (MT) allow the estimation of physical properties of tissue which are thought to reflect myelination, and are therefore likely to be useful for clinical application. Although a model describing a two-pool system under continuous wave-saturation has been available for two decades, generalizing such a model to pulsed MT, and therefore to in vivo applications, is not straightforward, and only recently have a range of equations predicting the outcome of pulsed MT experiments been proposed. These solutions of the 2-pool model are based on differing assumptions and involve differing degrees of complexity, so their individual advantages and limitations are not always obvious. This paper is concerned with the comparison of three differing signal equations. After reviewing the theory behind each of them, their accuracy and precision is investigated using numerical simulations under variable experimental conditions such as degree of T-1-weighting of the acquisition sequence and SNR, and the consistency of numerical results is tested using in vivo data. We show that while in conditions of minimal T-1-weighting, high SNR, and large duty cycle the solutions of the three equations are consistent, they have a different tolerance to deviations from the basic assumptions behind their development, which should be taken into account when designing a quantitative MT protocol. (c) 2008 Elsevier Inc. All rights reserved.