Paper
8 March 2013 Image guidance system for flexible endoscopes considering tissue deformation
Rainer Hoffmann, Michael Figl, Amar Bhatia, Marcus Kaar, Wolfgang Birkfellner, Andreas Püspök, Alfred Kratochwil, Johann B. Hummel
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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.
© (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Rainer Hoffmann, Michael Figl, Amar Bhatia, Marcus Kaar, Wolfgang Birkfellner, Andreas Püspök, Alfred Kratochwil, and Johann B. Hummel "Image guidance system for flexible endoscopes considering tissue deformation", Proc. SPIE 8671, Medical Imaging 2013: Image-Guided Procedures, Robotic Interventions, and Modeling, 867104 (8 March 2013); https://doi.org/10.1117/12.2007410
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KEYWORDS
Computed tomography

Image registration

3D image processing

Calibration

Endoscopy

Optical tracking

3D acquisition

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