1. A method for tracking position of features of a moving organ from at least one sequence of image frames of the moving organ, comprising: a) identifying at least a first feature and a second feature of the organ in a reference image frame of the at least one sequence of image frames; b) tracking position of the first and second features in other image frames of the at least one sequence of image frames in order to learn motion patterns of the first and second features; c) determining a dynamic geometric relation between the first and second features; and d) in the event that the first feature of the organ is obscured in a given image frame of the at least one sequence of image frames, determining position of the first feature in the given image frame using position of the second feature in the given image frame and the dynamic geometric relation between the first and second features as determined in step c).