Measurement of regional cerebral blood flow by intravenous injection of Xe133.

Clearance of Xenon 133 following intravenous injection has been used to perform atraumatic measurements of regional cerebral blood flow (rCBF). rCBF was computed by a two-compartmental analysis of the clearance curves associated with a correction for Xenon recirculation based on the end-tidal tracer concentration. Direct comparison was made between the results of this method and those obtained from the reference intracarotid method. A systematic analysis has shown that the results of the non-invasive method depend on the part of the clearance curves chosen for computation of rCBF. The best concordance with the intra-carotid method was found when the analysed part of the curve was situated between 3 and 11 min. after the beginning of the injection. Under these conditions, the differences between the results from the two methods did not exceed 10% of the flow values even for low flows. Such precision makes the atraumatic measurements of rCBF by intravenous injection of Xenon valuable for clinical applications.