1. A method for use in registering medical images in a medical imaging system, comprising: obtaining a fixed first image; obtaining a second image; normalizing the intensity of said first and second images; calculating gradient magnitudes of said first and second images; applying control point grids to said first and second images, wherein control points of said grids define regions of said first and second images; identifying said regions between said images having larger differences in at least one of intensity and gradient magnitude in relation to regions having smaller differences in corresponding intensity or gradient; and deforming the fixed first image to the second image, wherein regions having larger differences are utilized to drive deformation between the images, wherein said control points are classified as one that drive deformation and ones that are fixed, wherein said classification is based on at least one of intensity differences and gradient magnitude differences between corresponding control points of said first and second images.