NONINVASIVE THERMAL METHOD FOR QUANTIFYING TISSUE PERFUSION.

A noninvasive thermal probe has been constructed from two flake thermistors. A spherical heat transfer model of the heated flake thermistors was verified using numerical methods. Probe calibration is discussed. The ability to quantify accurately thermal conductivity with the noninvasive probe was demonstrated by testing with materials of known thermal properties. The ability to quantify accurately perfusion with the noninvasive probe was evaluated using an isolated rat liver perfusion technique. The isolated perfused liver technique allows for independent quantification of the true perfusion by collection of total venous flow and the use of radiolabeled microspheres for determination of the proportional distribution of total flow. Experimental results demonstrate that the noninvasive probe is quite sensitive to changes in the level of perfusion within the surface region of tissues.