Anderson G T, Valvano J W, Santos R R
Department of Electronics and Instrumentation, University of Arkansas, Little Rock 72204.
IEEE Trans Biomed Eng. 1992 Sep;39(9):877-85. doi: 10.1109/10.256420.
A microcomputer-based control system applies a combination of steady state and sinusoidal power to a thermistor probe which is inserted into the tissue of interest. The steady-state temperature response is an indication of the effective thermal conductivity (keff), which includes a component due to intrinsic conduction plus a convective component due to the tissue blood flow near the probe. By careful choice of the excitation frequency, the sinusoidal temperature response can be used to measure intrinsic thermal conductivity (km) in the presence of blood flow. Optimal sinusoidal heating frequency depends on the thermistor size. Experimental results in the alcohol-fixed canine kidney cortex show that perfusion is linearly related to the difference keff minus km. The instrument can measure tissue thermal conductivity with an accuracy of 2%. The instrument can resolve changes in perfusion of 10 mL/100g-min with a Thermometrics P60DA102M thermistor. The maximum error in measured perfusion is about 30%. When tissue trauma due to probe insertion is minimized, the self-heated thermistor method gives a reliable indication of local tissue blood flow.
基于微型计算机的控制系统将稳态和正弦功率的组合施加到插入到感兴趣组织中的热敏电阻探头。稳态温度响应是有效热导率（keff）的指示，其包括由于固有传导引起的分量以及由于探头附近组织血流引起的对流分量。通过仔细选择激励频率，正弦温度响应可用于在存在血流的情况下测量固有热导率（km）。最佳正弦加热频率取决于热敏电阻的尺寸。在酒精固定的犬肾皮质中的实验结果表明，灌注与keff减去km的差值呈线性相关。该仪器能够以2％的精度测量组织热导率。使用Thermometrics P60DA102M热敏电阻，该仪器能够分辨出10 mL/100g-min的灌注变化。测量灌注的最大误差约为30％。当由于探头插入引起的组织创伤最小化时，自热式热敏电阻方法可给出局部组织血流的可靠指示。
