Measurement of cerebral blood flow in rat brain by 19F-NMR detection of trifluoromethane washout

✍ Scribed by John A. Detre; Clifford J. Eskey; Alan P. Koretskyp

• Publisher: John Wiley and Sons
• Year: 1990
• Tongue: English
• Weight: 676 KB
• Volume: 15
• Category: Article
• ISSN: 0740-3194
• DOI: 10.1002/mrm.1910150106

✦ Synopsis

Abstract

The washout of trifluoromethane (CHF~3~) from rat cerebral cortex was monitored by ^19^F NMR. After 15 min of inhalation of 67% CHF~3~/33% O2 the fluorine signal detected was in a steady state. The CHF~3~ was switched off rapidly at the endotracheal tube and the washout detected with 12‐s time resolution. Two models were used to extract flow information, a simple exponential fit and a model which accounts for arterial CHF~3~ recirculation. In both cases, a two‐compartment model fit the data significantly better than a one‐compartment model. In both models, the faster time component varied with increasing __p__CO~2~, but no significant change in the slow component was detected. At control values of __p__CO~2~, there was a small difference in washout rate constants derived from the two models. At high __p__CO~2~, when tissue washout was comparable to arterial washout of CHF~3~, the model which accounted for arterial recirculation gave higher flows. Using this two‐compartment model with correction for recirculation, a control flow (__p__CO~2~ = 35 mm Hg) of 0.73 ± 0.04 ml/min/g was measured. Increasing plasma __p__CO~2~ increased the apparent flow six‐ to sevenfold with a 4.4% increase in flow per millimeter of Hg change in CO~2~. These results are qualitatively in agreement with results found by others using the washout of ^133^Xe. However, this method yields values for flow that are lower than those obtained using ^133^Xe washout, probably because of diffusion limitations of CHF~3~. © 1990 Academic Press, Inc.