Radioaerosol Inhalation Lung Scan in Pulmonary Emphysema

Perfusion and ventilation imagings of the lung are well established procedure for diagnosing pulmonary embolism, differentiation it from chronic obstructive lung disease, and making an early detection of chronic obstructive lung disease. To evaluate the usefulness of radioaerosol inhalation imaging (RII) in chronic obstructive lung disease, especially pulmonary emphysema, we analyzed RIIs of five normal adult non-smokers, five asymptomatic smokers (age 25-42 years with the mean 36), and 21 patients with pulmonary emphysema (age 59-78 years with the mean 67). Scintigrams were obtained with radioaerosol produced by a BARC nebuliser with 15 mCi of 99mTc-phytate. Scanning was performed in the anterior, posterior, and lateral projections after five to 10-minute inhalation of the radioaerosol on sitting position. The scans were analyzed and correlated with the results of pulmonary function studies and chest radiographs. Also lung perfusion scan with 99mTc-MAA was performed in 12 patients. In five patients, we performed follow-up scans for the evaluation of the effects of a bronchodilator. Based on the X-ray findings and clinical symptoms, pulmonary emphysema was classified into four types: centrilobular (3 patients), panlobular (4 patients), intermediate (10 patients), and combined (4 patients). RII findings were patternized according to the type, extent, and intensity of the aerosol deposition in the central bronchial and bronchopulmonary system and lung parenchyma. 10 controls, normal five non-smokers and three asymptomatic smokers revealed homogeneous parenchymal deposition in the entire lung fields without central bronchial deposition. The remaining two of asymptomatic smokers revealed mild central airway deposition. The great majority of the patients showed either central (9/21) or combined type (10/21) of bronchopulmonary deposition and the remaining two patients peripheral bronchopulmonary deposition. Parenchymal aerosol deposition in pulmonary emphysema was diffuse (6/21), discrete(6/21), intermediate (3/21), or combined (6/21). In 12 patients studied also with perfusion scans, perfusion defects matched closely with ventilation defects in location and configuration. But the size of the ventilation defects was generally larger than the perfusion defects. In all four patients treated with bronchodilators, the follow-up study demonstrated decrease in abnormal of radioaerosol deposition in the central airway with improvement of ventilation defects. RII was useful technique for the evaluation of regional ventilatory abnormality and the effects of treatment with bronchodilators in pulmonary emphysema.