The Clinical Application Of Cardiopulmonary Nuclear Medicine Research

Objective The pulmonary clearance rate of aerosolized ⁹⁹Tc^m - DTPA is a sensitive index for the measurement of lung epithelial permeability (LEP). It is well established that LEP increases in some pathological conditions. However, little is known about the influence of age on LEP. Accordingly, the aim of this study was to evaluate the relationship between age and LEP in healthy non-smokers.Methods Seventy-nine healthy non-smokers were enrolled. After breathing aerosolized ⁹⁹Tc^m - DTPA for 5 minutes, the counts of pulmonary radioactivity were continuously recorded for 30 minutes in 30 seconds per frame with gamma camera. Then exponential curve of the pulmonary radioactive counts versus time was plotted. The pulmonary clearance index (k) was calculated according to the curve. The following analysis was done: (1) To estimate the best regression model between age and k; (2) To compare the difference of k values between aged (≥ 60 yrs) and younger people (<60 yrs). Results Cubic regression was the best model in description of the relationship between pulmonary clearance index and age. The pulmonary clearance index in aged people is higher than that in younger people, but only on the middle and lower part of the lung. Conclusions LEP changes with age in healthy non-smokers and increases in aged people. It is helpful in investigating senescence and lung disease in aged people.