Free S L, Sisodiya S M, Cook M J, Fish D R, Shorvon S D
Epilepsy Research Group, Institute of Neurology, London, UK.
Cereb Cortex. 1996 Nov-Dec;6(6):830-6. doi: 10.1093/cercor/6.6.830.
The convolutions of the cerebral cortex are difficult to describe and delineate. Our understanding of the development of the brain and its associated maldevelopment would be assisted by quantitative analysis of the cortex. Volumetric magnetic resonance (MR) imaging provides high-resolution anatomical data from which we can reconstruct the white matter as a three-dimensional object and extract its surface (the grey/white matter interface). Three-dimensional fractal analysis of this surface is a method of quantifying the surface complexity dependent upon the variation of the surface area under different scales of inspection. We estimate the fractal dimension of the white matter surface for each hemisphere and 10 coronal blocks of each hemisphere in 30 normal adult subjects. These values are tightly distributed and have been used to define a normal range of fractal dimensions. Abnormal fractal dimensions were found in 8/16 subjects with epilepsy and a gyral abnormality observed on routine MR imaging; and in 9/23 subjects with epilepsy and normal routine MR imaging. These analytical techniques offer additional information about the structure of the cortex in normal brains and about abnormalities of structure in subjects with suspected but unobserved structural abnormalities.
大脑皮层的脑回很难描述和勾勒。对大脑发育及其相关发育异常的理解可通过对皮层的定量分析来辅助。容积磁共振（MR）成像提供了高分辨率的解剖数据，我们可以从中将白质重建为三维物体并提取其表面（灰质/白质界面）。对该表面进行三维分形分析是一种量化表面复杂性的方法，它取决于在不同检查尺度下表面积的变化。我们估计了30名正常成年受试者每个半球以及每个半球的10个冠状切片的白质表面分形维数。这些值分布紧密，并已用于定义分形维数的正常范围。在16名患有癫痫且在常规MR成像中观察到脑回异常的受试者中，有8名发现分形维数异常；在23名患有癫痫且常规MR成像正常的受试者中，有9名发现分形维数异常。这些分析技术提供了有关正常大脑皮层结构以及疑似但未观察到结构异常的受试者结构异常的额外信息。
