Search

In 8 patients with infectious hepatitis and in 10 controls the disappearance rates of 85Kr and 133Xe were measured externally after labeling hepatic tissue by retrograde simultaneous hepatic venous injections of the isotopes. As xenon has a higher affinity for fat than has krypton, the quotient between the halftime for 85Kr and for 133Xe could be used for calculation of hepatic fat content as well as the partition coefficients of the isotopes between hepatic tissue and blood. The estimated hepatic fat content was significantly higher in the patients than in the controls, 5.8 versus 3.6 per cent. The calculated partition coefficients in the controls were 1.09 and 1.13, respectively, for krypton and xenon. The corresponding values in the patients were significantly higher, 1.25 and 1.41, respectively. The clearances of the isotopes seemed to overestimate the average perfusion coefficient by 25 per cent, as judged from total hepatic blood flows and expected liver weights. A possible explanation might be local hyperemia in the injected areas. The present data indicate that this method can be used to estimate partition coefficients and hepatic fat content.

Samples of 133Xe in saline and blood were measured in 2-ml syringes of plastic and glass by different detectors. Good reproducibility with a coefficient of variation of 2% and good accuracy under varying conditions were obtained by a well scintillator with side hole and by a flat end scintillator with 6 cm distance to the sample. Despite the high uptake of xenon in the wall of the plastic syringes and their significant loss of activity of about 0.5 % per hour, they were for other reasons preferred to glass syringes.