Whole-brain susceptibility mapping at high field: A comparison of multiple- and single-orientation methods
Whole-brain susceptibility mapping at high field: A comparison of multiple- and single-orientation methods
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DOI：
10.1016/j.neuroimage.2010.06.070
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发表时间：
2010-11-01
期刊：
影响因子：
5.7
通讯作者：
Bowtell, Richard
中科院分区：
文献类型：
--
作者：
Wharton, Sam;Bowtell, Richard
对从7T采集的梯度回波(相位和模数)图像数据计算全脑三维磁化率图的三种不同方法的性能进行了优化和比较。所研究的方法是多方位方法，其中组合了与主场成几个不同角度的头部采集的图像数据，以及使用在单一方向上获取的数据的两种方法，第一种方法基于从计算中排除一些k空间数据(通过对偶极场核进行阈值处理)，而第二种方法结合了基于使用来自模数图像的信息的正则化方法。通过分析来自包含已知磁化率的不同隔室的体模的数据，对该方法进行了初始优化。作为这项工作的一部分，引入了一种新的高通滤波方法来去除基于相位数据的场图中的背景场。优化的方法被成功地应用于高分辨率(0.7 mm各向同性)全脑模数和在体采集的五名健康男性受试者的相位数据，年龄在25-30岁。多方位方法获得了高质量的磁化率图。相对于周围组织，静脉血管以及黑质和苍白球脑区表现出特别高的正磁化率偏移量，分别与高脱氧血红蛋白和非血红素铁含量一致。为了比较不同方法的性能，在深部灰质结构和皮质灰质和白质中绘制感兴趣区域。基于阈值的方法快速且简单使用，但低估了敏感度差异，并由于在k空间的困难区域中的噪声放大而显示出显著的伪影。规则化的单方向方法产生依赖于空间先验选择的对比度，但展示了产生与使用在场的多个方向获得的数据计算的磁化率图具有类似质量的磁化率图的潜力。(C)2010 Elsevier Inc.保留所有权利
Optimisation and comparison of the performance of three different methods for calculating three-dimensional susceptibility maps of the whole brain from gradient-echo (phase and modulus) image data acquired at 7 T is described. The methods studied are a multiple-orientation method in which image data acquired with the head at several different angles to the main field are combined and two methods which use data acquired at a single orientation the first of these is based on exclusion of some k-space data from the calculation (through thresholding of the dipolar field kernel), while the second incorporates a regularisation method that is based on using information from the modulus images The methods were initially optimised via analysis of data from a phantom containing different compartments of known susceptibility. As part of this work, a novel high-pass filtering methodology was introduced to remove background fields from field maps based on phase data The optimised methods were successfully applied to high-resolution (0 7 mm isotropic) whole-brain modulus and phase data acquired in vivo from five healthy male subjects, 25-30 years of age The multiple-orientation method yielded high quality susceptibility maps. out-performing the single-orientation methods Venous blood vessels as well as the substantia nigra and globus pallidus brain regions showed particularly high positive susceptibility offsets relative to surrounding tissue, consistent with high deoxyhemoglobin and non-heme iron content, respectively To compare the performance of the different methods, regions of interest were drawn in deep grey matter structures and in cortical grey and white matter The threshold-based approach was fast and simple to use, but underestimated susceptibility differences and showed significant artefacts due to noise amplification in difficult regions of k-space The regularised single-orientation method yielded contrast dependent on the choice of spatial priors, but demonstrated the potential to yield susceptibility maps of a similar quality to those calculated using data acquired at multiple orientations to the field. (C) 2010 Elsevier Inc. All rights reserved