Biopsy site re-localisation based on the computation of epipolar lines from two previous endoscopic images.

Tracking biopsy sites in endoscopic images can be useful to provide a visual aid for the guidance of surgical tools, for example when endoscopic guided biopsy is required. A new method for re-localisation of these sites is presented in this paper. It makes use of epipolar geometry properties between three images of the same site observed from different viewpoints with an endoscope. Two epipolar lines are derived from the two first images in the third image where the site needs to be re-localised. Their intersection corresponds to the location of the biopsy site. This method was tested with gastroscopic data from 2 patients with 9 series of three images of the oesophagus. The re-localisation error was estimated at less than 1.5 millimetres by a clinical endoscopist, which is sufficient for most clinical endoscopic applications.