Determination of the specific blood flow of the liver by inhalation of radioactive rare gases.

The technique applying the inhalation of radioactive rare gase is a new method to determine the specific blood flow of the liver. After inhalation of 133Xe, the course of activity is registered above liver and spleen as well as in the exspirated air. The perfusion is calculated from the resulting wash-out curves. The average value in healthy persons is 91 +/- 15 ml/100 g min. The reproducibility is 5 +/- 1%. The xenon wash-out is delayed in cirrhotic livers; the blood flow is significantly decreased and amounts to an average of 45 ml/100 g min. A delayed wash-out of xenon was also found in major fatty livers due to the high affinity of xenon to fat. The dependence of the partition coefficient on the fat content was investigated by Kitani and Winkler in homogenized liver tissue of different fat content. The question arises whether these in vitro findings can be transferred to in vivo wash-out curves. We therefore carried out first investigations on patients of known content of fat of the liver, applying a 85MKr-133 Xe-double measurement. According to results which have been achieved up to now, sufficient accuracy can only be obtained up to a fat content of 10%.