Effect of Inhaled Steroid Therapy on Distribution of Tc-99m DTPA Radioaerosol in Asthmatic Children

The aim of this study was to evaluate the effect of inhaled steroid therapy on the distribution of inhaled Tc-99m DTPA in asthmatic children. Twenty-one asthmatic children and 15 healthy controls were entered in this study. The distribution of radioaerosols was scored by using a modified standardized score system over both lungs and expressed as homogeneity score/patient. The baseline homogeneity score was calculated before the inhalation therapy of budesonide (400 g/day) for six months. The homogeneity score was repeated at the end of the second and sixth months of therapy. Asthmatic symptom scores and peak-flow rate variability, which were observed to improve throughout the study, were also recorded. Although homogeneity scores of the controls demonstrated no abnormality, mean baseline homogeneity scores of asthmatics was significantly high, 1.7 ± 0.4/patient, and decreased to 0.6 ± 0.2 and 0.3 ± 0.1/patient at the end of second and sixth months, respectively (p < 0.05). These results revealed significant improvement in the radioaerosol distribution after inhaled steroid therapy. It was concluded that the lack of homogeneity in the distribution of Tc99m-DTPA in the lung, as an indicator for ventilation defects, may be accepted as a useful, noninvasive tool to monitor the efficacy of the therapy with inhaled agents in childhood asthma.