The objective of this research is to combine the numerical, analytic, experimental, and medical expertise of the three investigators in order to produce an improved diagnostic technique for measuring thermal conductivity, thermal diffusivity, and perfusion using miniature self-heated thermistor probes. The proposed research will have four major efforts. The first task will use finite element numerical analysis to optimize the thermistor probe design, and measurement protocol. The second task will be an exhaustive experimental error analysis using an isolated rat liver preparation. The third task will be the collection of an in vitro thermal property data base. The thermal conductivity and diffusivity of human biopsy, and autopsy tissue will be measured. The fourth task will be to implement a clinical version of the existing microcomputer based instrument. Institutional Review Board approval of this instrument, with surface thermistor probes, will be requested in order to conduct future clinical studies. A combination of steady state and sinusoidal thermal power is delivered to a spherical thermistor positioned invasively within a tissue or noninvasively on the surface of a tissue. The heat is carried away from the probe into the tissue by thermal conduction, and perfusion. The finite element method is used to numerically solve the heat transfer between the heated thermistor and the perfused tissue. The electrical power and the resulting temperature rise are measured by the microcomputer instrument. These measurements are used to calculate the effective thermal conductivity which represents both the conductive and convective components of bioheat transfer. Because tissue blood flow strongly affects local heat transfer, the instrument is quite sensitive to perfusion. The funding of this proposal will translate into a long lasting improvement in patient care.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM031931-02
Application #
3280361
Study Section
Surgery and Bioengineering Study Section (SB)
Project Start
1986-09-08
Project End
1989-08-31
Budget Start
1987-09-01
Budget End
1989-08-31
Support Year
2
Fiscal Year
1987
Total Cost
Indirect Cost
Name
University of Texas Austin
Department
Type
DUNS #
City
Austin
State
TX
Country
United States
Zip Code
78713
Valvano, J W; Nho, S; Anderson, G T (1994) Analysis of the Weinbaum-Jiji model of blood flow in the canine kidney cortex for self-heated thermistors. J Biomech Eng 116:201-7
Anderson, G T; Valvano, J W (1994) A small artery heat transfer model for self-heated thermistor measurements of perfusion in the kidney cortex. J Biomech Eng 116:71-8
Anderson, G T; Valvano, J W; Santos, R R (1992) Self-heated thermistor measurements of perfusion. IEEE Trans Biomed Eng 39:877-85
Patel, P A; Valvano, J W; Pearce, J A et al. (1987) A self-heated thermistor technique to measure effective thermal properties from the tissue surface. J Biomech Eng 109:330-5