Quantification of age-related changes in the elastic texture of the human aortic wall by directional fractal curve

A new fractal feature, the Directional Fractal Curve (DFC), defined over an arc of 180° and composed of 90 fractal dimensions determined at intervals of arc of 2°, was developed to account for the anisotropic property of a fractal texture. The DFC of images with directional preference shows a periodic pattern; while the DFC of images with no definite directional preference tends to be a horizontal line. The DFC of the elastic texture exhibits a single peak and can be characterized by a sinusoidal function. The DFC was applied to examine an age-related structural change in the elastin network of the aortic wall exposed by scanning electron microscopy. Aortic samples were obtained from 44 human subjects with age range of 3 months to 103 years. Results show that the DFCs of these subjects decay significantly as age increases. This suggests that the elastin network may be characterized in terms of DFC which can be used to quantify structural modifications due to physiological changes such as ageing.