[Evaluation of regional cortical blood flow by thermal diffusion using a Peltier stack].

The possibility of quantitative evaluation of cerebral blood flow (CBF) by thermal diffusion has been reported, when the thermal gradient was created by a Peltier stack. We already described the linear relationship between the CBF and the inverse of thermal gradient elsewhere when the CBF measured by hydrogen clearance (Hydrogen CBF) was compared to the values estimated by thermal diffusion. In this paper, the correlation of linear relationship between the thermal CBF and hydrogen CBF in each animal was first investigated. Secondary, the possibility of in vitro calibration for quantitative evaluation was discussed. Two kinds of probes were manufactured. One was treated not to leak the heat from the Peltier stack except the sensors for the experimental or intraoperative use, and the other was not treated to minimize the size of probe for the long-term use by implantation into the subdural space. When the thermal CBF was compared to hydrogen CBF in each of 3 cats, a linear relationship was obtained in each and the values showing gradient and constant of the regression line were similar in each cat. Moreover, a good linear relationship was also observed when all measurements in 3 cats were included. These results suggested that there is no difference between each animal in the relationship of thermal and hydrogen CBF when the same probe is employed. In addition, the probe can be characterized with two values, and these are gradient and constant of the linear relationship. The fact that the blood flow is proportional to the heat conductivity indicates that the heat conductivity of some material is equivalent to some CBF value in the brain tissue.(ABSTRACT TRUNCATED AT 250 WORDS)