An extended image force model of snakes for medical image segmentation and smoothing

A scheme of the image force for Snakes, named the eSnake Model, has been introduced based on the electrostatic theory. To improve the ability for segmenting medical images with uneven grayscale intensity, a novel extended eSnake model, eeSnake, is developed to get the desirable image force distribution for Snakes. Breaking through the limitation of the Coulomb law, it can work better with the elasticity and balloon forces of Snakes than eSnake. The pre-calculated data stencil of distance functions is adopted to accelerate the computing speed of the potential field. The analysis points out that the eeSnake model can also function as a smoothing filter. Experiments show that the proposed eeSnake model is satisfactory in both segmentation and noise reduction applications. ? 2006 IEEE.EI

Diffusion characteristic analysis in human visual cortex

Since the birth of diffusion tensor imaging (DTI), diffusion characteristic has become a powerful tool to probe the internal structure of the subject. The diffusion anisotropy indices (DAIs) are parameters derived from DTI data which describe the morphological characteristics of diffusion tensor within specific range. It is of great importance to select a proper DAI for the analysis and interpretation of DTI data. In this work, the diffusion characteristic in human visual cortex is analysed with three DAIs: the commonly used fractional anisotropy (FA), ellipsoidal geometric ratio (EAR) proposed lately and ellipsoidal geometric ratio (EGR) that we proposed. The retinotopic mapping and surface-based analysis methods were applied to increase the power and precision studying longitudinal DAI changes in different visual fields (V1, V2, V3 et al). All three DAIs show the similar trend in visual fields, however, EGR and EAR both have higher magnitude and better contrast than FA. In addition, since EGR makes full use of the ellipsoidal volume information, its application result shows a certain improvement compared with EAR.Medical InformaticsPhysics, AppliedRadiology, Nuclear Medicine & Medical ImagingEICPCI-S(ISTP)