A measurement of V/V distribution by intravenous injection of Kr-81m and Tc-99m-MAA

Distribution of ventilation per unit lung volume (V/V) was measured by intravenous injection of Kr-81m and Tc-99m-MAA on 10 subjects having various pulmonary diseases. The distribution of V/V (R)Q obtained by this method was compared with that (V/V (R)V) obtained by the inhalation method of Kr-81m (V) and Xe-133 gas (V). The study was performed in sitting position. Kr-81m solution and Tc-99m-MAA was injected continuously to the antecubital vein during tidal breathing. V and V on inhalation study was measured with Kr-81m gas and Xe-133 gas respectively. The lung field was divided in about 30 slices with 6 mm thickness from top to bottom. Relative distribution of V/V was compared between V/V (R)Q and V/V (R)V for each subject. Correlation coefficient was 0.76 - 0.95 in 20 lungs of ten subjects, except for one lung. This result suggests that the distribution of V/V measured by Kr-81m and Tc-99m-MAA represents regional V/V in the lung. This method is useful to measure V/V when Xe-133 is not available. (author)