Liver blood flow measurement the interpretation of xenon133 clearance curves

Liver tissue perfusion can be measured by analysis of the clearance of the radioactive inert gases Xenon133 and Krypton85 from the liver. The technique commonly gives rise to multiexponential clearance curves which have previously been quoted as evidence of complex intrahepatic blood flow patterns. The clearance of 133Xe from the canine liver was studied in 17 dogs and by screening out extrahepatic radioactivity it was found that the true intrahepatic clearance is monoexponential. The slower components seen in the multiexponential curve recorded without screening represent 133Xe in tissue other than the liver and much of this activity was shown to originate from 133Xe which accumulates in the stomach and intestines. These findings simplify the interpretation of inert gas clearance curves in the measurement of liver blood flow and therefore encourage further application of the technique in both experimental and clinical situations.