Spiral CT colonography (virtual colonoscopy): Current status and future directions

CT colonography is a novel technique which provides a noninvasive examination of the colon for the detection of colorectal polyps. Following the acquisition of CT data within a single breath-hold, 3D images are created which provide an endoscopic visualization of the mucosal surface. The interactive use of 2D multiplanar reformations provide an extraluminal orientation. Edge-enhanced views, which simulate a barium enema, can provide an overview of the colonic anatomy and demarcate the focal findings. Sensitivity per polyp to detect 10 mm and greater lesions has ranged from 50% to 90%, with sensitivity per patient ranging from 80% to 90%. Key technical areas of investigation are computed aided diagnosis, novel 3D visualizations to unfold the colon, and stool tagging with digital stool subtraction. As further validation in more general patient cohorts is achieved, standardization and appropriate implementation will be important.