Fast macromolecular proton fraction mapping from a single off-resonance magnetization transfer measurement.
Fast macromolecular proton fraction mapping from a single off-resonance magnetization transfer measurement.
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DOI：
10.1002/mrm.23224
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发表时间：
2012-07
影响因子：
3.3
通讯作者：
Yarnykh, Vasily L.
中科院分区：
文献类型：
--
作者：
Yarnykh, Vasily L.
提出了一种新的磁化转移（MT）双池模型中大分子质子分数（MPF）的快速定量作图方法。该方法利用具有非共振饱和度的单个图像、用于数据归一化的参考图像以及用于全脑成像的总采集时间约为10 min的T1、B 0和B1图。MPF图是通过迭代求解矩阵脉冲MT方程与其他模型参数的约束值重建。基于误差传播规律，建立了描述噪声方差和约束参数偏离实际值偏差的理论误差模型。该方法进行了验证，通过比较与传统的多参数多点拟合的脉冲MT模型的基础上，从两个健康受试者和两个多发性硬化症患者的数据。理论和实验表明，该方法的精度取决于饱和脉冲的偏移频率和翻转角，这两个参数的最佳范围分别为4-7 kHz和600-900°。在最佳采样条件下，单点法能够实现<10%的相对MPF误差。与多参数拟合方法的比较显示了非常好的一致性，无显著偏倚，一致性限度约为± 0.7%。
A new method was developed for fast quantitative mapping of the macromolecular proton fraction (MPF) defined within the two-pool model of magnetization transfer (MT). The method utilizes a single image with off-resonance saturation, a reference image for data normalization, and T1, B0, and B1 maps with the total acquisition time ~10 min for whole-brain imaging. MPF maps are reconstructed by iterative solution of the matrix pulsed MT equation with constrained values of other model parameters. Theoretical error model describing the variance due to noise and the bias due to deviations of constrained parameters from their actual values was formulated based on error propagation rules. The method was validated by comparison with the conventional multi-parameter multi-point fit of the pulsed MT model based on data from two healthy subjects and two multiple sclerosis patients. It was demonstrated theoretically and experimentally that accuracy of the method depends on the offset frequency and flip angle of the saturation pulse, and optimal ranges of these parameters are 4-7 kHz and 600-900°, respectively. At optimal sampling conditions, the single-point method enables <10% relative MPF errors. Comparison with the multi-parameter fitting method revealed very good agreement with no significant bias and limits of agreement around ±0.7%.
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