A novel microthermal probe for the measurement of perfusion

Using micro-fabrication techniques a micro thermal probe has been developed in our laboratory to measure the thermal conductivity of biological tissues. This paper presents our latest experimental results which demonstrate the usefulness of the micro thermal probe in mapping the complicated perfusion field inside biological tissues. A perfused pig liver model has been constructed to simulate in vivo conditions. The portal vein and hepatic artery of a porcine liver were intubated and connected to a perfusion circuit. Saline water was perfused through the liver driven by a peristaltic pump. By varying the pumping rate of the perfused model, we measured the effective thermal conductivity at different perfusion rates in different locations. The results show that the effective thermal conductivity varies with the square root of the perfusion rate. Also, by rotating the micro probes, we observed a strong directional dependence of the effective thermal conductivity, revealing that perfusion is not a scalar but a vector field.

[1]  K. Kuroda,et al.  Effects of blood perfusion rate on the optimization of RF-capacitive hyperthermia , 1998, IEEE Transactions on Biomedical Engineering.

[2]  H. H. Pennes.  Analysis of tissue and arterial blood temperatures in the resting human forearm. 1948. , 1948, Journal of applied physiology.

[3]  J A Pearce,et al.  A self-heated thermistor technique to measure effective thermal properties from the tissue surface. , 1987, Journal of biomechanical engineering.

[4]  R L Mahajan,et al.  Temperature dependence of thermal conductivity of biological tissues , 2003, Physiological measurement.

[5]  Ming Yi,et al.  Micromachined Hot-Wire Thermal Conductivity Probe for Biomedical Applications , 2009, IEEE Transactions on Biomedical Engineering.

[6]  H. F. Bowman,et al.  Thermal diffusion probe and instrument system for tissue blood flow measurements: validation in phantoms and in vivo organs , 1994, IEEE Transactions on Biomedical Engineering.

[7]  R K Jain,et al.  Blood flow and heat transfer in Walker 256 mammary carcinoma. , 1979, Journal of the National Cancer Institute.

[8]  S. Weinbaum,et al.  A theoretical model for peripheral tissue heat transfer using the bioheat equation of Weinbaum and Jiji. , 1987, Journal of biomechanical engineering.

[9]  Leon Shargel,et al.  Applied biopharmaceutics and pharmacokinetics , 1980 .

[10]  M. Knudsen,et al.  Estimation of tissue blood flow from hyperthermia treatment data. , 1989, International journal of hyperthermia : the official journal of European Society for Hyperthermic Oncology, North American Hyperthermia Group.

[11]  X G Liang,et al.  A convenient method of measuring the thermal conductivity of biological tissue. , 1991, Physics in medicine and biology.

[12]  F. Prinzen,et al.  Blood flow distributions by microsphere deposition methods. , 2000, Cardiovascular research.

[13]  J.W. Valvano,et al.  Self-heated thermistor measurements of perfusion , 1992, IEEE Transactions on Biomedical Engineering.

[14]  B. Wood,et al.  Effects of perfusion on radiofrequency ablation in swine kidneys. , 2004, Radiology.

[15]  S. Goldberg,et al.  Improved tumor destruction with arsenic trioxide and radiofrequency ablation in three animal models. , 2006, Radiology.

[16]  Kenneth R. Holmes,et al.  MICROVASCULAR CONTRIBUTIONS IN TISSUE HEAT TRANSFER , 1980, Annals of the New York Academy of Sciences.

[17]  J. C. Jaeger,et al.  Conduction of Heat in Solids , 1952 .

[18]  H. F. Bowman,et al.  The simultaneous measurement of thermal conductivity, thermal diffusivity, and perfusion in small volumes of tissue. , 1984, Journal of biomechanical engineering.

[19]  Hong Cao,et al.  Measurement of directional thermal properties of biomaterials , 2001, IEEE Transactions on Biomedical Engineering.