Minati Ludovico, Aquino Domenico, Rampoldi Stefano, Papa Sergio, Grisoli Marina, Bruzzone Maria Grazia, Maccagnano Elio
Scientific Direction Unit, Fondazione Istituto Nazionale Neurologico Carlo Besta, via Celoria 11, Milan, Italy.
MAGMA. 2007 Dec;20(5-6):241-53. doi: 10.1007/s10334-007-0091-1. Epub 2007 Nov 29.
Clinical diffusion imaging is based on two assumptions of limited validity: that the radial projections of the diffusion propagator are Gaussian, and that a single directional diffusivity maximum exists in each voxel. The former can be removed using the biexponential and diffusional kurtosis models, the latter using generalised diffusion-tensor imaging. This study provides normative data for these three models.
Eighteen healthy subjects were imaged. Maps of the biexponential parameters D (fast), D (slow) and f (slow), of D and K from the diffusional kurtosis model, and of diffusivity D' were obtained. Maps of generalised anisotropy (GA) and scaled entropy(SE) were also generated, for second and fourth rank tensors. Normative values were obtained for 26 regions.
In grey versus white matter, D (slow) and D' were higher and D (fast), f (slow) and K were lower. With respect to maps of D', anatomical contrast was stronger in maps of D (slow) and K. Elevating tensor rank increased SE, generally more significantly than GA, in: anterior limb of internal capsule, corpus callosum, deep frontal and subcortical white matter, along superior longitudinal fasciculus and cingulum.
The values reported herein can be used for reference in future studies and in clinical settings.
临床扩散成像基于两个有效性有限的假设：扩散传播子的径向投影是高斯分布的，并且每个体素中存在一个单一的最大方向扩散率。前者可以使用双指数和扩散峰度模型去除，后者可以使用广义扩散张量成像去除。本研究提供了这三种模型的规范数据。
对18名健康受试者进行成像。获得了双指数参数D（快）、D（慢）和f（慢）的图谱，扩散峰度模型的D和K图谱，以及扩散率D'的图谱。还生成了二阶和四阶张量的广义各向异性（GA）和缩放熵（SE）图谱。获得了26个区域的规范值。
在灰质与白质中，D（慢）和D'较高，而D（快）、f（慢）和K较低。关于D'图谱，D（慢）和K图谱中的解剖对比度更强。在以下区域，提高张量阶数会增加SE，通常比GA更显著：内囊前肢、胼胝体、额叶深部和皮质下白质、沿上纵束和扣带。
本文报告的值可用于未来研究和临床环境中的参考。
