Kunicki A C B, Araújo L S, Sá F B, Stosic B, Barbosa C T F, Nogueira R A
Department of Animal Morphology and Physiology, Rural Federal University of Pernambuco, Recife, Pernambuco, Brazil.
Vet Ophthalmol. 2008 Jan-Feb;11(1):2-6. doi: 10.1111/j.1463-5224.2007.00589.x.
To study the applicability of the fractal dimension as a parameter for describing retinal vessel patterns in ophthalmically normal dogs.
The following strategy was adopted: (i) development of an experimental procedure to obtain digitalized photographs of the fundus; (ii) development of software to segment retinal vessel images and calculate the box-counting and radius of gyration fractal dimensions of the retinal vessels and diffusion-limited aggregation (DLA), a process with similar characteristics to retinal vessel morphology, and (iii) establishment of a standard curve for the fractal dimensions of segmented vessels.
Digitalized photographs of the fundus showed an adequate contrast between the vessels and the rest of the fundus for numerical analysis. The software developed produced a binary image of the retinal vessels permitting calculation of the fractal dimension. The mean values of the fractal dimensions calculated by the methods of box-counting and radius of gyration for the DLA were significantly different (t = -40.33, P approximately 0). The radius of gyration method was found to be more suitable for documenting the dimension of the DLA and, consequently, of the dog's retinal vessels.
This methodology may be useful to differentiate between normal and pathologic states of canine retinal vascularization.
研究分形维数作为描述眼科正常犬视网膜血管形态参数的适用性。
采用以下策略：（i）开发一种实验程序以获取眼底数字化照片；（ii）开发软件以分割视网膜血管图像，并计算视网膜血管的盒计数分形维数和回转半径分形维数以及扩散受限聚集（DLA），这是一个与视网膜血管形态具有相似特征的过程，以及（iii）建立分割血管分形维数的标准曲线。
眼底数字化照片显示血管与眼底其他部分之间有足够的对比度用于数值分析。所开发的软件生成了视网膜血管的二值图像，从而能够计算分形维数。通过盒计数法和回转半径法计算的DLA分形维数平均值有显著差异（t = -40.33，P约为0）。发现回转半径法更适合记录DLA的维数，进而适合记录犬视网膜血管的维数。
该方法可能有助于区分犬视网膜血管化的正常和病理状态。
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