Biomedical Imaging Lab, Agency for Science Technology and Research, 30 Biopolis Street, #07-01 Matrix, Singapore.
Int J Comput Assist Radiol Surg. 2011 Jul;6(4):489-505. doi: 10.1007/s11548-010-0538-0. Epub 2010 Dec 16.
Although the brain has been extensively studied, relationships of gray (GM) to white (WM) matters in individual sections as typically acquired and read radiologically have not yet been examined. A novel GM/WM-based approach with a compact whole brain representation is introduced and applied to study the brain and perform neuroimage processing.
The gray to white matter ratio GWR defined as GM/(GM+WM) was calculated for 3T T1-weighted axial, coronal, and sagittal sections of 75 normal subjects. The mean (normative) GWR curves were employed to describe the normal brain and quantify aging and to illustrate pathology detection and characterization.
The mean GWR curves characterize the normal brain by only six, neuroanatomy-related numbers. The regions with a significant GWR decline with age surround the ventricular system. The GWR decline rate in males is higher (-0.17%/year) than females (-0.14%/year); moreover, males show a significantly higher decline in middle to elder group. The GWR decline from young (≤25 years) to middle (26-40 years) age group (males/females -0.31%/-0.34%/year) is significantly higher than that from middle to elder (>40 years) group (males/females -0.13/-0.07%/year).
The GWR-based analysis is useful to characterize normal brain, determine significant regions of interest, and quantify healthy aging. It has potential applications in brain compression, comparison, morphometry, normalization, and detecting and quantifying pathologies, which open new avenues in computer-assisted neuroradiology from screening to large brain databases searching.
尽管大脑已经得到了广泛的研究，但个体层面上典型获取和放射学阅读的灰质（GM）与白质（WM）之间的关系尚未得到研究。本文提出并应用了一种基于 GM/WM 的新方法，以紧凑的全脑表示形式来研究大脑并进行神经影像学处理。
在 75 名正常受试者的 3T T1 加权轴位、冠状位和矢状位切片上计算 GM 与（GM+WM）的比值 GWR。采用平均（正常）GWR 曲线来描述正常大脑并量化衰老，以及说明病理检测和特征描述。
平均 GWR 曲线仅用六个与神经解剖学相关的数字来描述正常大脑。与年龄相关的 GWR 下降的区域环绕着脑室系统。男性的 GWR 下降率（-0.17%/年）高于女性（-0.14%/年）；此外，男性在中年到老年组的下降速度明显更高。从年轻（≤25 岁）到中年（26-40 岁）年龄组的 GWR 下降率（男性/女性-0.31%/-0.34%/年）明显高于从中年到老年（>40 岁）年龄组（男性/女性-0.13/-0.07%/年）。
基于 GWR 的分析可用于描述正常大脑、确定有意义的感兴趣区域并量化健康衰老。它在大脑压缩、比较、形态计量学、归一化以及检测和量化病理方面具有潜在的应用，为计算机辅助神经放射学开辟了新的途径，从筛查到大型大脑数据库搜索。
