Determining the Mechanical Properties of Excised and Whole Organ Soft Tissues
A.E. Kerdok, R. Howe*, T. Maeno**, CIMIT SImulations group ***
*Biorobotics Laboratory, Harvard University
**BioRobotics Laboratory, Keio University
***CIMIT Simulations Group, Massachusetts General Hospital
Support provided by United States Army Medical Research and Material Command
Graduate Student Support provided by the Whitaker Foundation
Access to the physical standard database for validating real-time simulation of soft tissues: Truth Cube
Motivation
Realistic medical simulations can aid in surgical training and planning given that an accurate biomechanical understanding of the body's internal make-up exists. The aim of this research is to accurately determine the complex behavior of soft tissues via imaging, indentation, implanted devices, boundary condition measurement methods, and mathematical modeling. Ultimately, a tissue atlas of the representative organs chosen (liver, kidney, and spleen) will be produced that can serve as a ground truth for numerous modeling and feedback applications.
Validation and Standards
We are developing a silicone rubber model that will serve as the foundation on which new models of soft tissues will be validated. A 10 x 10 x 10 cm cube with CT fiducial markers is being developed for testing in indentation, compression, shear, tension, and rotation. The resulting force, strain and displacement fields will be made available via the web and will serve as a standard over which soft tissue models can be compared and validated.
Access to the physical standard database for validating real-time simulation of soft tissues: Truth Cube
Devices
The research will focus on in-vivo, in-situ characterization of the liver, kidney and spleen under slow deformation as in therapeutic manipulation (on the order of 1 to 10 Hz). Devices have been and will be further developed that measure the force and displacement of both excised tissues and in-vivo whole organs as a function of velocity.
![[pic]](kerdok_device1.gif) ![[pic]](kerdok_device2.gif) Takashi Maeno's T-needle device for internal local tissue measurements, 2001 |
| The indentation and implanted devices will be used to obtain both ex-vivo and in-vivo measurements of the organ components (parenchyma, capsule, and vessels). In addition, applying small displacements via a robotic arm and measuring the resulting reaction forces and torques will determine the in-situ boundary conditions of the whole kidney. |
![[pic]](kerdok_model.gif) |
Modeling Whole Organs Imaging modalities such as CT and MR tagging as well as finite methods will be used in conjunction with the testing devices to obtain accurate strain field displacements of the organs to correlate the 3D geometry with material property information for use in developing accurate mathematical models. |
| The models will be used to validate both the non-linear constitutive relation chosen and the testing devices themselves. Lastly, these models will be optimized to provide real time simulation of the slow deformation of the liver, kidney, and spleen in-situ. |
Related Research
Karol Miller from the University of Western Australia and his research on very soft tissue mechanical properties .
Frank Tendick from the University of California at San Francisco and his research on surgical robotics and abdominal organ tissue measurements.
Stanford University Medical Center's National Biocomputation Center
Stanford University Center for Advanced Technology in Surgery (CATSS)
University of Teubingen Germany lab
For more information contact Amy E. Kerdok, kerdok@fas.harvard.edu
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