CT colonography: data acquisition and patient preparation techniques.

The success of a virtual endoscopy is essentially dependent on the image quality of the corresponding 3-dimensional reconstructions. Before loading image data on a post-processing computer, certain prerequisites concerning the source data must be met. To carry out a CT colonography, the source data must be of good quality. High spatial resolution in all geometrical directions, continuous data acquisition without gaps, and artefact-free images are pivotal factors influencing source data. A generally applicable rule is that the size of the smallest detectable polyp is limited by the nominal slice thickness, emphasizing the ultimate importance of the initially chosen primary slice collimation. Furthermore, calculation of an endoluminal view is impossible without sufficient distension of the bowels. Thorough patient preparation that accommodates the technical circumstances for post-processing is also required for attaining a high sensitivity in polyp detection.