1. A method of coronary vessel segmentation and visualization, comprising the steps of: providing a digitized coronary image, said image comprising a plurality of intensities associated with a 3-dimensional grid of voxels; placing a plurality of seed points along an estimated centerline of a coronary vessel; selecting a seed point and constructing a cyclic graph around said seed point in a plane perpendicular to the centerline at the seed point; performing a multi-scale-mean shift filtering in said perpendicular plane to estimate image gradient values; detecting a boundary of said vessel using a minimum-mean-cycle optimization that minimizes a ratio of a cost of a cycle in said graph to a length of said cycle; constructing a sub-voxel accurate vessel boundary about a point on said centerline; and refining the location of said centerline point from said sub-voxel accurate boundary, wherein said steps of constructing a sub-voxel accurate vessel boundary and refining the centerline point location are repeated until convergence.