Esteban Francisco J, Sepulcre Jorge, de Mendizábal Nieves Vélez, Goñi Joaquín, Navas Juan, de Miras Juan Ruiz, Bejarano Bartolome, Masdeu Jose C, Villoslada Pablo
Department of Experimental Biology, Systems Biology and Neurodynamics Unit, Faculty of Experimental and Health Sciences, University of Jaén, Campus Las Lagunillas s/n, 23071, Jaén, Spain.
Neuroimage. 2007 Jul 1;36(3):543-9. doi: 10.1016/j.neuroimage.2007.03.057. Epub 2007 Apr 10.
The brain white matter (WM) in multiple sclerosis (MS) suffers visible and non-visible (normal-appearing WM (NAWM)) changes in conventional magnetic resonance (MR) images. The fractal dimension (FD) is a quantitative parameter that characterizes the morphometric variability of a complex object. Our aim was to assess the usefulness of FD analysis in the measurement of WM abnormalities in conventional MR images in patients with MS, particularly to detect NAWM changes. First, we took on a voxel-based morphometry approach optimized for MS to obtain the segmented brain. Then, the FD of the whole grey-white matter interface (WM border) and skeletonized WM was calculated in patients with MS and healthy controls. To assess the FD of the NAWM, we focused our analysis on single sections without lesions at the centrum semiovale level. We found that patients with MS had a significant decrease in the FD of the entire brain WM compared with healthy controls. Such a decrease of the FD was detected not only on MR image sections with MS lesions but also on single sections with NAWM. Taken together, the results showed that FD identifies changes in the brain of patients with MS, including in NAWM, even at an early phase of the disease. Thus, FD might become a useful marker of diffuse damage of the central nervous system in MS.
在多发性硬化症（MS）中，大脑白质（WM）在传统磁共振（MR）图像中会出现可见和不可见（外观正常的白质，NAWM）变化。分形维数（FD）是一个定量参数，用于表征复杂物体的形态测量变异性。我们的目的是评估FD分析在测量MS患者传统MR图像中WM异常方面的有用性，特别是检测NAWM变化。首先，我们采用了一种针对MS优化的基于体素的形态测量方法来获取分割后的大脑。然后，计算了MS患者和健康对照者全灰白质界面（WM边界）和骨架化WM的FD。为了评估NAWM的FD，我们将分析重点放在半卵圆中心水平无病变的单个切片上。我们发现，与健康对照者相比，MS患者全脑WM的FD显著降低。这种FD的降低不仅在有MS病变的MR图像切片上被检测到，而且在有NAWM的单个切片上也被检测到。综上所述，结果表明FD能够识别MS患者大脑中的变化，包括NAWM中的变化，即使在疾病的早期阶段也是如此。因此，FD可能成为MS中枢神经系统弥漫性损伤的一个有用标志物。
