Correlation between cerebral blood volume and cerebral blood flow in the cat

Blood flow and blood volume were measured simultaneously in the same cerebral region in anaesthetized cats with controlled respiration. The measurements were made with the same scintillation-detector, using the freely diffusible indicator 133 Xenon for flow determinations and the intra-vascular indicator RISA (131I) for volume recordings. A very high correlation was found between volume and flow changes (r = .96, p < 0.001). This finding indicates that variations of regional cerebral blood volume are accompanied by proportional blood flow changes.