A method includes obtaining first and second ultrasound image data andcomputing a coarse transverse flow field by applying an optical flow technique to compare the second ultrasound image data to the first ultrasound image data at a coarse scale. The method further includes computing a fine transverse flow field by applying optical flow technique to compare the second ultrasound image data to the first ultrasound image data at a scale that is finer than the coarse scale and superimposing the fine transverse flow field onto the coarse transverse flow field to form a first combined flow field.
