title: A navigation system for flexible endoscopes using abdominal 3D ultrasound.
abstract: A navigation system for flexible endoscopes equipped with ultrasound (US) scan heads is presented. In contrast to similar systems, abdominal 3D-US is used for image fusion of the pre-interventional computed tomography (CT) to the endoscopic US. A 3D-US scan, tracked with an optical tracking system (OTS), is taken pre-operatively together with the CT scan. The CT is calibrated using the OTS, providing the transformation from CT to 3D-US. Immediately before intervention a 3D-US tracked with an electromagnetic tracking system (EMTS) is acquired and registered intra-modal to the preoperative 3D-US. The endoscopic US is calibrated using the EMTS and registered to the pre-operative CT by an intra-modal 3D-US/3D-US registration. Phantom studies showed a registration error for the US to CT registration of 5.1 mm±2.8 mm. 3D-US/3D-US registration of patient data gave an error of 4.1 mm compared to 2.8 mm with the phantom. From this we estimate an error on patient experiments of 5.6 mm.
authors.affiliation: Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, 1090 Wien, Austria.
authors.forename: R
authors.initials: R
authors.lastname: Hoffmann
authors.forename: M
authors.initials: M
authors.lastname: Kaar
authors.forename: Amon
authors.initials: A
authors.lastname: Bathia
authors.forename: Amar
authors.initials: A
authors.lastname: Bathia
authors.forename: A
authors.initials: A
authors.lastname: Lampret
authors.forename: W
authors.initials: W
authors.lastname: Birkfellner
authors.forename: J
authors.initials: J
authors.lastname: Hummel
authors.forename: M
authors.initials: M
authors.lastname: Figl
mesh_terms: D002138:Calibration; D019723:Endoscopes / Q000592:standards*; D019160:Endosonography / Q000295:instrumentation* / Q000379:methods; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000295:instrumentation* / Q000379:methods; D019047:Phantoms, Imaging; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods