Methods of thermal blood flow measurement.

All techniques for measuring thermal blood flow have in common a small heat source and two temperature difference sensors placed in or on the tissue. The measured temperature difference can be quasistationary, nonstationary or constant, depending upon the heating pattern. Its extent and course, respectively the heating output in the case of pulse fluvography, are dependent upon blood flow. Conversion of the heat transport coefficient into specific blood flow is possible only if the vessels in the temperature field are predominantly capillaries. Both the sink and the pore theory make it possible to draw conclusions about specific blood flow from the measurement values obtained.