부산대학교 도서관

The difference in the values of cerebral blood flow (CBF) as determined by two nonivasive methods, i.e., the 133-xenon inhalation method and the 133-xenon intravenous injection method (IV method), was analyzed in 12 subjects with the mean age of 58 years (range 36-84). Two serial measurements were done on the same day with an interval of 12 to 25 minutes in 11 subjects. The blood flow of the fast compartment (gray matter) of the brain (F1) was calculated as well as the initial slope index (ISI), the relative weight (W1) and the fractional flow (FF1 ) of the fast compartment.The mean value of the hemispheric F1 in the IV method (71.5±10.8ml/100g brain/min) was significantly higher than that in the inhalation method (64.3±7.3), whereas the mena value of the hemispheric W1 in the IV method (39.3±4.2%) was significantly lower than that in the inhalation method (41.3±3.9). In order to clarify whether differences are due to the unreliability in estimating the arterial concentration curve from the exhaled air curve, direct arterial sampling as well as exhaled air counting after the introduction of 133-xenon was done in 4 other subjects with normal arterial gas values. A distinct difference between the two curves was found in 4 out of 4 in the inhalation method and in 3 out of 4 in the IV method. It is concluded that (1) there is a difference between the concentration curves in the arterial blood and in the expired air after 133-xenon inhalation as well as after 133-xenon intravenous injection, even if there is no obvious pulmonary function disturbance and no abnormality in the arterial gas tensions, and (2) the differences in F1 and W1 as determined by the two noninvasive methods may be explained by the observed difference of the two concentration curves.