Two Methods for Calculating Regional Cerebral Blood Flow from Emission Computed Tomography of Inert Gas Concentrations

Abstract

Two methods were described for calculation of [human] regional cerebral blood flow from completed tomographic data of radioactive inert gas distribution in a slice of [human] brain tissue. The tomographic picture apparently gives the average inert gas concentration in each pixel over data collection periods of 30-60 s. In the early picture method a single picture taken during maximum inert gas concentration (by intraarterial injection or by inhalation) was analyzed. In the sequence of pictures method the alterations in local inert gas concentration were followed over time. The proposed methods were implemented using synthetic data of xenon-133 emission computed tomography and some of the difficulties likely to be encountered in practice were stressed.