The C15O2 Build-up Technique to Measure Regional Cerebral Blood Flow and Volume of Distribution of Water

Abstract

A new method to measure regional CBF (rCBF) and volume of distribution of water is presented. It centres on recording the tissue build-up and retention of ¹⁵O-labelled water during the continuous inhalation of ¹⁵O-labelled carbon dioxide. Simultaneously, the arterial concentration is continuously monitored, and corrections for delay and dispersion in the recorded response are made by curve fitting. The values for the volume of distribution of water obtained in four normal subjects were close to reported in vitro values. Using the same fixed distribution volumes for both build-up and steady-state studies resulted in comparable rCBF values for both techniques.