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扩散张量磁共振成像体模表现出反常扩散。

Diffusion tensor MRI phantom exhibits anomalous diffusion.

作者信息

Ye Allen Q, Hubbard Cristinacce Penny L, Zhou Feng-Lei, Yin Ziying, Parker Geoff J M, Magin Richard L

出版信息

Annu Int Conf IEEE Eng Med Biol Soc. 2014;2014:746-9. doi: 10.1109/EMBC.2014.6943698.

Abstract

This paper reports diffusion weighted MRI measurements of cyclohexane in a novel diffusion tensor MRI phantom composed of hollow coaxial electrospun fibers (average diameter 10.2 μm). Recent studies of the phantom demonstrated its potential as a calibration standard at low b values (less than 1000 s/mm<;sup>2<;/sup>) for mean diffusivity and fractional anisotropy. In this paper, we extend the characterization of cyclohexane diffusion in this heterogeneous, anisotropic material to high b values (up to 5000 s/mm<;sup>2<;/sup>), where the apparent diffusive motion of the cyclohexane exhibits anomalous behavior (i.e., the molecular mean squared displacement increases with time raised to the fractional power 2α/β). Diffusion tensor MRI was performed at 9.4 T using an Agilent imaging scanner and the data fit to a fractional order Mittag-Leffler (generalized exponential) decay model. Diffusion along the fibers was found to be Gaussian (2α/β=l), while diffusion across the fibers was sub-diffusive (2α/β<;l). Fiber tract reconstruction of the data was consistent with scanning electron micrograph images of the material. These studies suggest that this phantom material may be used to calibrate MR systems in both the normal (Gaussian) and anomalous diffusion regimes.

摘要

本文报道了在一种由中空同轴电纺纤维(平均直径10.2μm)组成的新型扩散张量磁共振成像体模中对环己烷的扩散加权磁共振成像测量。近期对该体模的研究表明,在低b值(小于1000 s/mm²)下,它有潜力作为平均扩散率和分数各向异性的校准标准。在本文中,我们将环己烷在这种非均质、各向异性材料中的扩散特性研究扩展到高b值(高达5000 s/mm²),在该高b值下,环己烷的表观扩散运动表现出异常行为(即分子均方位移随时间以分数幂2α/β增加)。使用安捷伦成像扫描仪在9.4 T下进行扩散张量磁共振成像,并将数据拟合到分数阶米塔格 - 莱夫勒(广义指数)衰减模型。发现沿纤维的扩散是高斯型的(2α/β = 1),而跨纤维的扩散是次扩散型的(2α/β < 1)。对数据进行的纤维束重建与该材料的扫描电子显微镜图像一致。这些研究表明,这种体模材料可用于在正常(高斯)和异常扩散区域校准磁共振系统。

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