T Lueth

Publications of T Lueth

• Automatic correction of registration errors in surgical navigation systems.

  Authors: Wolfgang Wittmann, Thomas Wenger, Benjamin Zaminer, Tim C Lueth

  IEEE transactions on bio-medical engineering. 07/2011; 58(10):2922-30.

  Surgical navigation systems are used widely among all fields of modern medicine, including, but not limited to ENT- and maxillofacial surgery. As a fundamental prerequisite for image-guided surgery,Surgical navigation systems are used widely among all fields of modern medicine, including, but not limited to ENT- and maxillofacial surgery. As a fundamental prerequisite for image-guided surgery, intraoperative registration, which maps image to patient coordinates, has been subject to many studies and developments. While registration methods have evolved from invasive procedures like fixed stereotactic frames and implanted fiducial markers toward surface-based registration and noninvasive markers fixed to the patient's skin, even the most sophisticated registration techniques produce an imperfect result. Due to errors introduced during the registration process, the projection of navigated instruments into image data deviates up to several millimeter from the actual position, depending on the applied registration method and the distance between the instrument and the fiducial markers. We propose a method that allows to automatically and continually improve registration accuracy during intraoperative navigation after the actual registration process has been completed. The projections of navigated instruments into image data are inspected and validated by the navigation software. Errors in image-to-patient registration are identified by calculating intersections between the virtual instruments' axes and surfaces of hard bone tissue extracted from the patient's image data. The information gained from the identification of such registration errors is then used to improve registration accuracy by adding an additional pair of registration points at every location where an error has been detected. The proposed method was integrated into a surgical navigation system based on paired points registration with anatomical landmarks. Experiments were conducted, where registrations with deliberately misplaced point pairs were corrected with automatic error correction. Results showed an improvement in registration quality in all cases.

• Experimental validation of a tissue-joining implant providing flexible adaptation to the thickness of the stomach wall.

  Authors: Heba Aguib, Daniel Roppenecker, Tim C Lueth

  IEEE transactions on bio-medical engineering. 10/2010; 58(2):429-34.

  Endoscopy is gradually replacing open surgery in the gastrointestinal tract. Therefore, novel medical devices and instrumentation are required, such as flexible miniaturized mechanisms for tissueEndoscopy is gradually replacing open surgery in the gastrointestinal tract. Therefore, novel medical devices and instrumentation are required, such as flexible miniaturized mechanisms for tissue joining and manipulation. In this paper, an absorbable implant for the purpose of long-term tissue fixation is presented. An experimental validation of the implant design and functionality is introduced. The implant achieves tissue penetration and provides flexible adaptation according to the thickness of two stomach walls. This mechanism is easy as it is based on push-pull principle using unidirectional forces. The shape optimization of each implant part occurs by varying design-influencing factors. The load transmission on postmortem porcine tissue was measured in the frame of the experimental setup. The feasibility of the implant was tested, and the forces needed for the intended application quantified. The implant successfully achieves tissue penetration, load transmission, adjustment, and fixation. It is a new alternative to conventional tissue-joining mechanisms.