Comparison of quantitative autoradiographic and xenon-133 clearance methods: correlation of gray and white matter cerebral blood flow with compartmental blood flow indices.

The relationships between CBF in gray and white matter to those of the fast and slow components of xenon-133 clearance curves remain uncertain. CBF was measured in 13 anaesthetized baboons under a variety of conditions, using both the xenon-133 clearance technique and [14C]iodoantipyrine quantitative autoradiography. There was a linear relationship between CBF, as determined by the stochastic (height/area) analysis of the clearance curve, and mean CBF determined from the autoradiograms (r = 0.94, p less than 0.001, slope = 0.86 +/- 0.09). There was also a linear correlation between the fast-flow component (measured with xenon-133) and blood flow in the cerebral gray matter (measured with [14C]iodoantipyrine) (r = 0.92, p less than 0.001, slope = 0.69 +/- 0.15) and between the slow-flow component (with xenon-133) and blood flow in white matter (with [14C]iodoantipyrine) (r = 0.79, p less than 0.01, slope = 0.81 +/- 0.10). In the primate brain, the fast- and slow-flow indices therefore appear to be representative of CBF in gray matter and white matter, respectively, whereas the stochastic analysis provides a stable measure of mean CBF within the tissue monitored.