Three-dimensional fast single-point macromolecular proton fraction mapping of the human brain at 0.5 Tesla
Three-dimensional fast single-point macromolecular proton fraction mapping of the human brain at 0.5 Tesla
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DOI：
10.21037/qims-19-1057
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发表时间：
2020-07-01
影响因子：
2.8
通讯作者：
Yarnykh, Vasily L.
中科院分区：
文献类型：
--
作者：
Anisimov, Nikolay V.;Pavlova, Olga S.;Yarnykh, Vasily L.
快速单点大分子质子分数（MPF）成像是一种新的磁共振成像（MRI）方法，能够定量评估神经组织中的髓鞘含量。迄今为止，所报告的MPF标测的技术实现使用了高场MRI设备（1.5 T或更高），而低场应用可能会因信噪比（SNR）限制和短T-1而带来挑战。本研究的目的是评价0.5T下人脑MPF标测的可行性。三维MPF标测方案根据单点合成参考方法实施，该方法包括提供质子密度、T1和磁化转移对比度权重的三个扰相梯度回波序列。从三名健康志愿者获得全脑MPF图，空间分辨率为1.5x1.5x2 mm（3），总扫描时间为19分钟。在一系列白色和灰质结构中测量MPF值，并与3 T磁场的文献数据进行比较。MPF图使白色和灰质之间的对比度高，对富铁结构（如苍白球、黑质和齿状核）中的顺磁效应显著不敏感。0.5 T时的MPF值与3 T时的MPF值非常一致。本研究证明了低场MRI快速MPF标测的可行性和脑MPF值与磁场的独立性。所呈现的结果证实了MPF作为基于MRI的髓磷脂含量测量的绝对尺度在宽范围的磁场强度上的实用性，并将快速MPF映射的适用性扩展到廉价的低场MRI硬件。
Fast single- point macromolecular proton fraction (MPF) mapping is a recent magnetic resonance imaging (MRI) method enabling quantitative assessment of myelin content in neural tissues. To date, the reported technical implementations of MPF mapping utilized high-field MRI equipment (1.5 T or higher), while low-field applications might pose challenges due to signal-to-noise ratio (SNR) limitations and short T-1. This study aimed to evaluate the feasibility of MPF mapping of the human brain at 0.5 T. The three-dimensional MPF mapping protocol was implemented according to the single-point syntheticreference method, which includes three spoiled gradient-echo sequences providing proton density, T1, and magnetization transfer contrast weightings. Whole-brain MPF maps were obtained from three healthy volunteers with spatial resolution of 1.5x1.5x2 mm(3) and the total scan time of 19 minutes. MPF values were measured in a series of white and gray matter structures and compared with literature data for 3 T magnetic field. MPF maps enabled high contrast between white and gray matter with notable insensitivity to paramagnetic effects in iron-rich structures, such as globus pallidus, substantia nigra, and dentate nucleus. MPF values at 0.5 T appeared in close agreement with those at 3 T. This study demonstrates the feasibility of fast MPF mapping with low-field MRI equipment and the independence of brain MPF values of magnetic field. The presented results confirm the utility of MPF as an absolute scale for MRI-based myelin content measurements across a wide range of magnetic field strengths and extend the applicability of fast MPF mapping to inexpensive low-field MRI hardware.