[Determination of local brain blood flow by means of switched heating]

It is demonstrated by model experiments that the determination of stationary and instationary data (amplitude and shape of the heating signal) allows the two components of local brain perfusion (flow rate and volume flux) to be measured separately. Since perfusion and temperature are measured at the same site, the convection data are free of variations of the local brain temperature. The dependence of the amplitude of the heating signal on the flow rate is described by the equation Ao = a - e-bv + c, with the parameters a, b, c being represented as a function of the convection-free space around the sensing probe. It is shown by animal-experimental data that the magnitude of the convection-free space around the sensing probe is variable. A tentative algorithm is proposed for practical application of the method.