title: Feasibility of automated matching of supine and prone CT-colonography examinations.
abstract: Matching of prone and supine positions in CT colonography may improve accuracy of polyp detection. The purpose of this study was to investigate the feasibility of automatic prone-supine matching in CT-colonography using proven polyps as fixed points of reference. The method is based on similarities in the direction of centre-lines and allows for compression and extraction of the centre-lines in both positions. To illustrate the impact of the match error of the new method in practice, the visibility of the matched polyps in a primary three-dimensional unfolded cube setting was determined as well. The method was compared with a method that relies on the normalized distance along the centre-line (NDAC method). The median absolute match error was 14 mm (range 0-59 mm, average 20 mm) either proximal or distal from the actual polyp in prone position. In the observer study, 70% (26/37) of the polyps were directly visible in prone view. The overall difference in median absolute match error between both methods was small (2 mm), although half way along the centre-line there were polyps with substantial differences in match error (larger with NDAC). We concluded that automated prone-supine matching of CT-colonography studies is feasible and has a low match error. The difference with the NDAC method was small and not significant, although half way along the centre-line some differences were seen.
authors.affiliation: Department of Radiology, Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: A H
authors.initials: AH
authors.lastname: de Vries
authors.forename: R
authors.initials: R
authors.lastname: Truyen
authors.forename: J
authors.initials: J
authors.lastname: van der Peijl
authors.forename: J
authors.initials: J
authors.lastname: Florie
authors.forename: R E
authors.initials: RE
authors.lastname: van Gelder
authors.forename: F
authors.initials: F
authors.lastname: Gerritsen
authors.forename: J
authors.initials: J
authors.lastname: Stoker
mesh_terms: D000465:Algorithms; D001331:Automation; D003111:Colonic Polyps / Q000000981:diagnostic imaging*; D023881:Colonography, Computed Tomographic / Q000379:methods*; D005240:Feasibility Studies; D006801:Humans; D016684:Prone Position; D016683:Supine Position