Ali K. Hamou and Mahmoud R. El-Sakka, "Optical Flow Active 
                  Contours with Primitive Shape Priors for Echocardiography", 
                  EURASIP Journal on Advances in Signal Processing, Vol. 2010, 
                  (10 pages).
               
               
               
               Abstract
               
               
               
                  Accurate delineation of object borders is a highly desirable 
                  in echocardiography, especially at the left ventricle. Among
                  other model-based techniques, active contours (or snakes) 
                  provide a unique and powerful approach to image analysis. In 
                  this work, we propose the use of a new external energy for a 
                  gradient vector flow (GVF) snake, being the optical flow of a
                  moving sequence (modeling the mechanical movement of the 
                  heart). This external energy can provide additional 
                  information to the active contour model garnering adequate 
                  results for moving sequences. An automatic iterative primitive
                  shape prior was also applied in order to further improve the 
                  results of a GVF snake, when dealing with especially noisy 
                  echocardiographic images. Results were compared with 
                  expert-defined segmentations yielding acceptable sensitivity, 
                  precision rate and overlap ratio performance.