Display of 3-D Ultrasonic Images

Abstract

Three-dimensional (3-D) ultrasonic images made up of a “stack” of adjacent digitized B-scans are displayed as a volume image using the method of numerical projection. This display method involves the generation by a computer, of two-dimensional digital projection images of the display volume viewed from any desired direction. They are formed by summing the “intensity” values of the individual volume picture elements (voxels) of the 3-D B-scan along the set of paths which project the 3-D image array onto a plane. Stereo-pair projection images generated at two angles of “view” differing by 2° to 8° are utilized to visualize the volume image in three dimensions. The 3-D display of a “stack” of B-scans may result in the obscuring of some portions of the image due to superposed “bright” structures unless this undesirable effect is overcome by selective enhancement of features of interest in the 3-D B-scan. These enhancement methods are selective “tissue dissolution” and “numerical dissection” whereby portions of the 3-D B-scan are either partially “dissolved” or totally eliminated from the volume before projection to enhance the visibility of desired structure. Because they operate on the 3-D image array before projection and not on the resulting projection image, they are both effective and highly selective as visual enhancement methods.