Fantastic Voyage of the Virtual Colon

Abstract

We pioneered a visualization-based alternative to conventional optical colonoscopy, called virtual colonoscopy (VC), for screening patients for colonic polyps, the precursor of colon cancer. Unlike optical colonoscopy, VC is patient friendly since the patient undergoes a less rigorous bowel preparation. VC is also a fast, non-invasive, more accurate, and cost-effective procedure for mass screening of colon polyps. In VC, the patient’s abdomen is imaged by a helical or multi-slice computed tomography (CT) scanner during a 40-second singlebreath-hold. Supine and prone scans are acquired, each typically consists of 350 to 700 axial 512×512 images of sub-millimeter resolution. A 3D model of the colon is then reconstructed from the CT scan by automatically segmenting the colon out of the rest of the abdomen and employing an electronic cleansing algorithm for computer-based removal of the residual material and accurate reconstruction of the soft surface behind the removed material. This is accomplished using a novel segmentation rays algorithm. The visualization software, running on a PC, allows the physician to interactively navigate through the colon using a physically-based navigation system with fast volume rendering for visualization and the center line of the colon as a guide for the navigation. An intuitive user interface with customized tools supports measurements and virtual biopsy to inspect suspicious regions.