title: Re-localisation of a biopsy site in endoscopic images and characterisation of its uncertainty.
abstract: Endoscopy guided probe-based optical biopsy is a new method for detecting sites for tissue biopsy and treatment. After detection, it can be useful to provide a visual aid in the endoscopic images to the endoscopist for example for guidance of forceps to the biopsy sites detected optically. A new method for re-localisation of these sites during the endoscopic examination is presented in this paper. It makes use of a sequence of endoscopic images, where the biopsy site location is known, in order to derive the same number of epipolar lines as images in the sequence projected onto a subsequent target image where the re-localised biopsy site needs to be computed. The location of the re-localised biopsy site is found by minimisation of the sum of squared distances to the epipolar lines. The method also determines analytically the uncertainty of the re-localised biopsy site. This provides the endoscopist with a confidence region around the re-localised biopsy site and a measure of the re-localisation precision. Simulations confirmed that the analytical uncertainty has the potential to be a good estimation of the experimental uncertainty. The method was tested on a physical phantom and on real data from four patients with eight sequences of images acquired during gastroscopy. The re-localisation precision and accuracy were estimated at 1 millimetre or better, which is sufficient for re-localisation of optical biopsy sites.
authors.affiliation: Centre for Medical Image Computing, University College London, Gower Street, London, UK. b.allain@ucl.ac.uk
authors.forename: Baptiste
authors.initials: B
authors.lastname: Allain
authors.forename: Mingxing
authors.initials: M
authors.lastname: Hu
authors.forename: Laurence B
authors.initials: LB
authors.lastname: Lovat
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Cook
authors.forename: Tom
authors.initials: T
authors.lastname: Vercauteren
authors.forename: Sebastien
authors.initials: S
authors.lastname: Ourselin
authors.forename: David J
authors.initials: DJ
authors.lastname: Hawkes
mesh_terms: D000465:Algorithms; D001471:Barrett Esophagus / Q000473:pathology*; D001706:Biopsy / Q000379:methods*; D003627:Data Interpretation, Statistical; D016099:Endoscopy, Gastrointestinal / Q000379:methods*; D004947:Esophagus / Q000473:pathology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D010363:Pattern Recognition, Automated / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity