Locally applied 133Xenon for the measurement of regional cerebral blood flow (rCBF): an experimental study in the pig.

A method for measuring regional cerebral blood flow has been developed. On pig brain cortex a 1 cm2 size polyester film was placed, under which 0.6-1.3 mCi of 133Xenon in 2-4 microliter of saline was applied atraumatically. The wash-out process was registered with an external detector, and can be described as a sum of monoexponential functions. The first component of the curve, obtained by curve resolution, indicates blood flow in grey matter and the second slow component indicates blood flow in white matter. When total ischaemia was induced, there was no wash-out of the isotope. Freezing the brain after isotope application at different stages during the wash-out showed isotope in both grey and white matter. The isotope did not diffuse into the polyester film. This technique was also used in studies on the spinal medulla where white matter is outermost and grey innermost. The wash-out curve obtained consisted of only one monoexponential function; blood flow from grey matter was not present in the wash-out curve. For calculation of cerebral blood flow a modified two-compartment model was used. It is concluded that this method measures local cerebral blood flow in both grey and white matter. The method can be used clinically to measure the local cerebral blood flow during neurosurgical operations.