title: [Orientation of endoscopic images: rectification by gravity].
abstract: A known problem in endoscopic surgery (especially with flexible video endoscopes) is the absence of a stable horizon in endoscopic images displayed on a monitor. With our "ENDOrientation" approach, image rectification, even in non-rigid endoscopic surgery (particularly NOTES), can be realized with a tiny MEMS tri-axial inertial sensor placed on the tip of an endoscope. This sensor measures the impact of gravity on each of the three orthogonal accelerometer axes in real time. After an initial calibration and temporal filtering of these three data steams, the rotation angle of an endoscope can be estimated directly. The achievable sampling rate of the inertial sensor is above the usual endoscopic video frame rate of 25 Hz; the rotation accuracy is approximately one degree. The image rectification can be performed in real time by digitally rotating the endoscopic video signal. Improvements and benefits have been evaluated in animal studies: coordination and movement of different instruments was rated to be much more intuitive with a stable horizon on endoscopic images. The recorded time stamps and position tracks clearly support this observation.
authors.affiliation: Zentralinstitut für Medizintechnik und Lehrstuhl für Mustererkennung, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Deutschland. hoeller@zimt.uni-erlangen.de
authors.forename: Kurt
authors.initials: K
authors.lastname: Höller
authors.forename: Armin
authors.initials: A
authors.lastname: Schneider
authors.forename: Jasper
authors.initials: J
authors.lastname: Jahn
authors.forename: Javier
authors.initials: J
authors.lastname: Gutierrez
authors.forename: Thomas
authors.initials: T
authors.lastname: Wittenberg
authors.forename: Alexander
authors.initials: A
authors.lastname: Meining
authors.forename: Stefan
authors.initials: S
authors.lastname: von Delius
authors.forename: Joachim
authors.initials: J
authors.lastname: Hornegger
authors.forename: Hubertus
authors.initials: H
authors.lastname: Feussner
mesh_terms: D019723:Endoscopes; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006112:Gravitation; D007089:Image Enhancement / Q000295:instrumentation*; D055617:Micro-Electrical-Mechanical Systems / Q000295:instrumentation*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014159:Transducers