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Proceedings Paper

Image guidance system for flexible endoscopes considering tissue deformation
Author(s): Rainer Hoffmann; Michael Figl; Amar Bhatia; Marcus Kaar; Wolfgang Birkfellner; Andreas Püspök; Alfred Kratochwil; Johann B. Hummel
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Paper Abstract

This paper describes a navigation system for flexible endoscopes equipped with ultrasound scan heads. In contrast to similar systems additional abdominal 3D ultrasound images are used to achieve the required image fusion. An abdominal 3D US image has to be taken preoperatively before the CT scan. The CT is calibrated by means of the optical tracking system (OTS) and the transformation between CT and the calibrated 3D US can be calculated without image registration. Immediately before intervention takes place, a pre-interventional 3D US tracked with an electromagnetic tracking system (EMTS) is acquired and registered intra-modal to the preoperative US. Therefore, we can replace a direct 2D/3D registration from the endoscopic US to the pre-operative CT by an intra-modal USUS registration and tracker calibrations. To consider tissue deformation we implemented an approach using leading points. First, the US images were pre-processed by calculating importance images. The whole information of the image is then reduced to a set of expressive leading points calculated from the importance image. Once the vector field of corresponding leading points is found, a deformation field can be calculated. We found a target registration error for the whole transformation chain from a US pixel to a CT voxel of 4:34 ± 2:56mm (ten targets) on a phantom without deformation.

Paper Details

Date Published: 8 March 2013
PDF: 8 pages
Proc. SPIE 8671, Medical Imaging 2013: Image-Guided Procedures, Robotic Interventions, and Modeling, 867104 (8 March 2013); doi: 10.1117/12.2007410
Show Author Affiliations
Rainer Hoffmann, Medizinische Univ. Wien (Austria)
Michael Figl, Medizinische Univ. Wien (Austria)
Amar Bhatia, Medizinische Univ. Wien (Austria)
Marcus Kaar, Medizinische Univ. Wien (Austria)
Wolfgang Birkfellner, Medizinische Univ. Wien (Austria)
Andreas Püspök, Medizinische Univ. Wien (Austria)
Alfred Kratochwil, Medizinische Univ. Wien (Austria)
Johann B. Hummel, Medizinische Univ. Wien (Austria)
Wilhelminenspital Vienna (Austria)

Published in SPIE Proceedings Vol. 8671:
Medical Imaging 2013: Image-Guided Procedures, Robotic Interventions, and Modeling
David R. Holmes; Ziv R. Yaniv, Editor(s)

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