Medical Community: Abstracts




ARRS, American Roentgen Ray Society:

Virtual colonoscopy (VC) uses CT images and a computer visualization system to virtually navigate within a reconstructed 3-D model of the colon, searching for polyps. There are currently two approaches for VC. The first utilizes the actual 2-D images with direct 3-D correlation for problem areas. The problem with this approach is that it is frequently difficult to differentiate oblique and longitudinally oriented folds from small polyps. The second approach uses 3-D endoscopic navigation of the colon with the 2-D images used for problem solving. This latter approach mimics actual colonoscopy. However, as with actual colonoscopy, it is difficult for VC to ensure that all areas of the mucosa have been evaluated. This is particularly true in and around the haustral folds and around sharp turns or bends.

This exhibit displays a novel approach to solving this latter problem utilizing automatic field of view monitoring. During fly-through guided navigation the visualized colon surface can be marked and measured. Counting the visible surface voxels and comparing this number to the total of all surface voxels yields the percentage of lumen surface visualized. After antegrade and retrograde fly-throughs, all "patches" of connected surface area not yet seen are identified, measured and sorted by size. Clinically significant patches, the smallest diameter defined being > 5mm, are presented to the viewer, who quickly reviews each by direct visualization by sequentially stepping through the sorted list.

This exhibit will demonstrate how this approach to CT colonoscopy ensures a near 100% direct visualization of the mucosal surface. In addition, it will be shown that this system's ease of use adds little to the procedure time. This method of performing VC may provide better direct visualization of the entire colon than actual colonoscopy.

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