Li Gang, Nie Jingxin, Wang Li, Shi Feng, Gilmore John H, Lin Weili, Shen Dinggang
Department of Radiology and BRIC, University of North Carolina at Chapel Hill, NC, USA.
Department of Radiology and BRIC, University of North Carolina at Chapel Hill, NC, USA; School of Psychology, South China Normal University, Guangdong, China.
Neuroimage. 2014 Apr 15;90:266-79. doi: 10.1016/j.neuroimage.2013.12.038. Epub 2013 Dec 27.
Quantitative measurement of the dynamic longitudinal cortex development during early postnatal stages is of great importance to understand the early cortical structural and functional development. Conventional methods usually reconstruct the cortical surfaces of longitudinal images from the same subject independently, which often generate longitudinally-inconsistent cortical surfaces and thus lead to inaccurate measurement of cortical changes, especially for vertex-wise mapping of cortical development. This paper aims to address this problem by presenting a method to reconstruct temporally-consistent cortical surfaces from longitudinal infant brain MR images, for accurate and consistent measurement of the dynamic cortex development in infants. Specifically, the longitudinal development of the inner cortical surface is first modeled by a deformable growth sheet with elasto-plasticity property to establish longitudinally smooth correspondences of the inner cortical surfaces. Then, the modeled longitudinal inner cortical surfaces are jointly deformed to locate both inner and outer cortical surfaces with a spatial-temporal deformable surface method. The method has been applied to 13 healthy infants, each with 6 serial MR scans acquired at 2 weeks, 3 months, 6 months, 9 months, 12 months and 18 months of age. Experimental results showed that our method with the incorporated longitudinal constraints can reconstruct the longitudinally-dynamic cortical surfaces from serial infant MR images more consistently and accurately than the previously published methods. By using our method, for the first time, we can characterize the vertex-wise longitudinal cortical thickness development trajectory at multiple time points in the first 18 months of life. Specifically, we found the highly age-related and regionally-heterogeneous developmental trajectories of the cortical thickness during this period, with the cortical thickness increased most from 3 to 6 months (16.2%) and least from 9 to 12 months (less than 0.1%). Specifically, the central sulcus only underwent significant increase of cortical thickness from 6 to 9 months and the occipital cortex underwent significant increase from 0 to 9 months, while the frontal, temporal and parietal cortices grew continuously in this first 18 months of life. The adult-like spatial patterns of cortical thickness were generally present at 18 months of age. These results provided detailed insights into the dynamic trajectory of the cortical thickness development in infants.
定量测量出生后早期阶段动态纵向皮质发育对于理解早期皮质结构和功能发育非常重要。传统方法通常独立重建同一受试者纵向图像的皮质表面，这常常产生纵向不一致的皮质表面，从而导致皮质变化测量不准确，特别是对于皮质发育的顶点映射。本文旨在通过提出一种从婴儿脑纵向磁共振图像重建时间上一致的皮质表面的方法来解决这个问题，以准确一致地测量婴儿动态皮质发育。具体而言，首先通过具有弹塑性性质的可变形生长片对皮质内表面的纵向发育进行建模，以建立皮质内表面的纵向平滑对应关系。然后，使用时空可变形表面方法对建模的纵向皮质内表面进行联合变形，以定位皮质内表面和外表面。该方法已应用于13名健康婴儿，每名婴儿在2周、3个月、6个月、9个月、12个月和18个月龄时进行了6次连续磁共振扫描。实验结果表明，与先前发表的方法相比，我们结合纵向约束的方法能够更一致、准确地从婴儿磁共振序列图像重建纵向动态皮质表面。通过使用我们的方法，我们首次能够描绘出生命最初18个月内多个时间点的顶点纵向皮质厚度发育轨迹。具体而言，我们发现在此期间皮质厚度的发育轨迹与年龄高度相关且区域异质性，皮质厚度在3至6个月增加最多（16.2%），在9至12个月增加最少（小于0.1%）。具体来说，中央沟仅在6至9个月时皮质厚度有显著增加，枕叶皮质在0至9个月时有显著增加，而额叶、颞叶和顶叶皮质在生命的最初18个月持续生长。皮质厚度的成人样空间模式通常在18个月龄时出现。这些结果为婴儿皮质厚度发育的动态轨迹提供了详细的见解。
