Fractal Dimension Analysis of PET-MRI Liver Images for Various ROI’s Sizes

Abstract

In this study, a fractal analysis is applied to Magnetic Resonance Images (MRI) of the liver simultaneously to PET imaging. The analysis was performed to examine the influence of the size of the region of interest (ROI) in calculating the fractal dimension. MRI from 31 healthy subjects were used for analysis, several or a dozen frames from each, giving a total of 426 images. Five different algorithms of fractal dimension calculation (box-counting, rectangular prism surface area, power spectral density, triangular prism surface area and the intensity difference scaling) are tested. Two sizes of ROI’s were analyzed: 128 x 128 pixels and 64 x 64 pixels. The greatest similarities in the analyzed ROIs were obtained using the intensity difference scaling algorithm but others gave acceptable results.