Liver Tissue Analysis

Our goal is to search accurate liver tissue deformation models and to validate these models for surgical simulation using high resolution Micro Computed Tomography (Micro-CT) or medium resolution Cone-Beam CT (CBCT) images. The liver tissue deformation details in the contact region between the tissue and the probe can be detected and rendered for small force loads using high resolution Micro-CT images or medium resolution CBCT images. We have validated the linear elastic model, the linear viscous model and the hyperelastic neo-Hooke's model. More efforts will be made to search more accurate liver tissue deformation models and their validations. Topological changes in the contact region of the probe with the tissue are addressed and rendered.
Research Team
Aly A. Farag CVIP Director farag@cvip.uofl.edu
Hongjian Shi Research Assistant hshi@cairo.spd.uofl.edu
Rachid Fahmi Research Assistant rachid@cvip.uofl.edu
Dongqing Chen Research Assistant dqchen@cvip.uofl.edu
Methods
The finite element method incorporating the material mechanical properties is used in liver tissue deformation modeling. Different models will yield different results. Search accurate models and validation of these models are main tasks in realization of accurate modeling. Our validation is realized by scanning the undeformed tissue and the deformed tissue using high resolution Micro-CT images or medium resolution Cone-beam CT images for different force loads. Evaluation of the probe displacement and the volume difference of the deformed volume from experiments and the deformed volume from simulation are performed in validation process. Superimposing of the deformed volumes from experiments and simulations are rendered in both solid and zoomed wire frame.

Results

Some superimposing results achieved of the deformed volumes from experiments and simulations are rendered in both solid and zoomed wire frame. The listed are the results for the linear elastic model, the linear viscous model, and the neo-Hooke's hyperelastic model:

Publications
1. H. Shi, Aly A. Farag, R. Fahmi and D. Chen “Validation of Finite Element Models of Liver Tissue using Micro-CT and CBCT,” IEEE Transactions on Biomedical Engineering – Vol. 55, No. 3, pp. 978-984, March 2008
2. A. Farag, D. Chen, H. Hassan, "3D colon object reconstruction framework in CT colonography,” Proceedings of the 22nd International Conference on Computer-Assisted Radiology and Surgery (CARS-08), June 25-28, 2008. Barcelona, Spain.
3. Hongjian Shi, and Aly A. Farag, "Validating Linear Elastic and Linear Viscoelastic Models of Lamb Liver using Cone-Beam CT", Proc. of Computer Assisted Radiology and Surgery, 2005.
4. Aly A. Farag, Hongjian Shi, Rachid Fahmi, and M. Voor, "Basic Experiments and Finite Element Analysis of Soft Tissues'', Book chapter in Biomechanics applied to Computer Assisted Surgery, 2005.

Acknowledgement / Sponsors
We would like to thank the University of Louisville for its sponsorship. We also would like to thank all people who gave help during the manufacturing of the device as well as during the experimental setup, especially the other members in the medical group.