Automated 3-D extraction and evaluation of the inner and outer cortical surfaces using a Laplacian map and partial volume effect classification
Automated 3-D extraction and evaluation of the inner and outer cortical surfaces using a Laplacian map and partial volume effect classification
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DOI：
10.1016/j.neuroimage.2005.03.036
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发表时间：
2005-08-01
期刊：
影响因子：
5.7
通讯作者：
Evans, AC
中科院分区：
文献类型：
--
作者：
Kim, JS;Singh, V;Evans, AC
精确重建人脑皮层内外表面是神经成像分析的重要目标，包括可视化、形态测量和脑映射。我们小组以前开发的使用邻近度的解剖分割（ASP）算法提供了一种拓扑保持的皮质表面变形方法，该方法已被广泛用于上述目的。然而，由于灰色物质表面和白色物质表面之间的允许距离范围的限制，算法中用于确保拓扑保持的约束条件偶尔会产生不正确的厚度测量。这个问题在具有紧密折叠的脑回的小儿脑图像中特别突出。本文提出了一种新的方法，用于改进传统的ASP算法，利用部分体积信息，通过概率分类，以允许拓扑结构保存在一个较小的限制范围内的皮质厚度值。新算法还通过掩盖皮层下组织来纠正岛叶皮层的分类。对于70个儿童大脑，通过三种方法进行了改进算法约束拉普拉斯ASP（CLASP）的验证实验：（i）表面掩蔽灰质（GM）和传统组织分类GM之间的体积匹配，（ii）模拟和CLASP提取表面之间的表面匹配，以及（iii）同一受试者16次MRI扫描之间表面重建的可重复性。在基于体积的评估中，CLASP WM和GM表面所包围的体积与分类的GM体积相匹配，比使用传统ASP精确13%。在基于表面的评估中，使用合成厚皮质，模拟和提取表面之间的平均差异为4.6 +/- 1.4个单位（对于传统ASP）和0.5 +/- 0.4个单位（对于CLASP）。在一项重复性研究中，与ASP相比，CLASP对GM表面产生的RMS误差降低了30%，对WM表面产生的RMS误差降低了8%。(c)2005年爱思唯尔公司All rights reserved.
Accurate reconstruction of the inner and outer cortical surfaces of the human cerebrum is a critical objective for a wide variety of neuroimaging analysis purposes, including visualization, morphometry, and brain mapping. The Anatomic Segmentation using Proximity (ASP) algorithm, previously developed by our group, provides a topology-preserving cortical surface deformation method that has been extensively used for the aforementioned purposes. However, constraints in the algorithm to ensure topology preservation occasionally produce incorrect thickness measurements due to a restriction in the range of allowable distances between the gray and white matter surfaces. This problem is particularly prominent in pediatric brain images with tightly folded gyri. This paper presents a novel method for improving the conventional ASP algorithm by making use of partial volume information through probabilistic classification in order to allow for topology preservation across a less restricted range of cortical thickness values. The new algorithm also corrects the classification of the insular cortex by masking out subcortical tissues. For 70 pediatric brains, validation experiments for the modified algorithm, Constrained Laplacian ASP (CLASP), were performed by three methods: (i) volume matching between surface-masked gray matter (GM) and conventional tissue-classified GM, (ii) surface matching between simulated and CLASP-extracted surfaces, and (iii) repeatability of the surface reconstruction among 16 MRI scans of the same subject. In the volume-based evaluation, the volume enclosed by the CLASP WM and GM surfaces matched the classified GM volume 13% more accurately than using conventional ASP. In the surface-based evaluation, using synthesized thick cortex, the average difference between simulated and extracted surfaces was 4.6 +/- 1.4 unit for conventional ASP and 0.5 +/- 0.4 unit for CLASP. In a repeatability study, CLASP produced a 30% lower RMS error for the GM surface and a 8% lower RMS error for the WM surface compared with ASP. (c) 2005 Elsevier Inc. All rights reserved.