Effects of corticosteroid inhalation therapy on lung ventilation and alveolar permeability in asthma using TC-99M DTPA radioaerosol inhalation lung scintigraphy.

This study evaluates the effects of steroid inhalation on lung ventilation (LV) and alveolar permeability (AP) in 26 patients with asthma. The homogeneity of LV was evaluated as the inhalated Tc-99m diethylene triamine pentaacetic acid (DTPA) radioaerosol depositing ratios of the central 1/3 over peripheral 1/3 of the left lung. It is shown as a distribution factor (DF) in this study. The damage in AP was measured from the speed of Tc-99m DTPA radioaerosol clearance curves from the peripheral alveoli of the left lung and is represented as a slope in this study. The baseline LV and AP were calculated before an inhalation therapy of 0.05 mg beclomethasone dipropionate four times daily for one week, then the studies were repeated after treatment to evaluate the effects of inhalation therapies. The results revealed a significantly improved homogeneity of LV in 16/26 (62%) cases (DF: 0.79 +/- 0.32 vs 0.59 +/- 0.22, P = 0.0001), but no apparent change in AP (slope: 1.18 +/- 0.78 vs 1.25 +/- 0.88, P = 0.052) after the treatment. In conclusion, a corticosteroid inhalation therapy for asthma can improve the peripheral LV, but can not change the AP according to the findings of Tc-99m DTPA radioaerosol inhalation lung scintigraphy. We suggest that the widely available Tc-99m DTPA radioaerosol inhalation lung scintigraphy, coupled with the evaluation of LV and AP could contribute to any disorder involving both alveoli and airways.