Guiding navigation in colonoscopy.
BACKGROUND: Nonrigid environments such as the human colon present unique challenges for the navigator in maintaining spatial orientation. Conventional wisdom suggests that a navigational aid, similar to a map, that provides critical shape information would be useful. This article presents a design concept for a colonoscopy navigational aid and the results of an experiment conducted to evaluate the display for supporting navigation and spatial orientation in simulated colonoscopy. METHODS: A navigational aid was designed to present shape information in an augmented reality display. A total of 14 untrained subjects performed a colonoscopy procedure in rigid and nonrigid colon models, with and without the navigational aid display, in a Latin square design. Performance measures such as time, distance or efficiency of travel, and location and direction error were recorded, together with subjective measures of confidence and workload. RESULTS: The results showed that, unlike navigating in rigid environments, the subjects spent more time navigating in the nonrigid environment (p < 0.01) and traveled a longer total distance (p = 0.01). The navigational aid had no effect on performance, as compared with the no aid condition. However, subjective measures showed that the subjects were more confident about their determination of location and direction (p < 0.01). They also preferred having the aid during navigation. CONCLUSION: A navigational aid or map that provides shape information does not seem to improve performance in colonoscopy. In fact, it may lead to a false sense of security about location and orientation in the colon. The value of a map for training purposes remains to be examined.