Biomedical Engineering Reference
In-Depth Information
Quadratic Corotated Finite Elements
for Real-Time Soft Tissue Registration
Stefan Suwelack, Sebastian R
€
ohl, R
€
udiger Dillmann, Anna-Laura Wekerle,
Hannes Kenngott, Beat M
€
uller-Stich, C´line Alt, and Stefanie Speidel
Abstract Organ motion due to respiration and contact with surgical instruments can
significantly degrade the accuracy of image-guided surgery. In most applications, the
ensuing soft tissue deformations have to be compensated in order to register preoper-
ative planning data to the patient. Biomechanical models can be used to perform
registration based on sparse intraoperative sensor data. Using elasticity theory, the
approach can be formulated as a boundary value problemwith displacement boundary
conditions. In this paper, we propose to use corotated finite elements (FE) with
quadratic shape functions as a robust and accurate model for real-time soft-tissue
registration. A detailed numerical analysis reveals that quadratic FE perform signifi-
cantly better than linear corotated FE for high resolution meshes. We also show that
the method achieves nearly the same registration accuracy as a complex nonlinear
viscoelastic material model. Furthermore, a phantom experiment demonstrates how
the model can be used for intraoperative liver registration.
1
Introduction
Computer-assisted surgery (CAS) systems rely on preoperative planning data to
provide the surgeon with important information such as the position of risk and
target structures during the intervention. The accuracy of the registration can be
severely degraded by soft tissue deformations caused by respiratory motion and
surgical instruments. Most intraoperative imaging modalities (e.g., endoscopes,
S. Suwelack (
*
) • S. Rohl • R. Dillmann • S. Speidel
Department for Computer Science, Institute for Anthropomatics, Karlsruhe Institute
of Technology, Karlsruhe, Germany
e-mail:
suwelack@kit.edu
A.-L. Wekerle • H. Kenngott • B. M
uller-Stich • C. Alt
Department of General, Visceral and Transplantation Surgery, Heidelberg University Hospital,
Heidelberg, Germany
€
