Dynamic imaging of pulmonary ventilation in children using digital subtraction radiography

Digital subtraction radiography is a sensitive method for imaging changes in pulmonary aeration during the respiratory cycle. The findings of 75 consecutive dynamic pulmonary examinations performed on 49 pediatric patients using this technique were reviewed together with the findings at chest radiography and, in 18 cases, with bronchoscopy. Symmetric diaphragmatic movement and synchronous, homogeneous variation in the attenuation of lung parenchyma indicated normal conditions in 9 (18%) patients. The most common abnormal finding (36 patients) was an asynchronous variation in the attenuation of the lung parenchyma. A greatly diminished or absent variation in attenuation was diagnostic for a serious air passage obstruction in 7 children. Other abnormal findings were a lowered amplitude of diaphragmatic movement, asynchronous diaphragmatic movement and mediastinal shift. In 10 patients (20%) the dynamic study showed parenchymal abnormalities when chest radiography was normal. Bronchoscopy was performed in 4 of these 10 patients and showed abnormalities in each case.