[Evaluation of diffuse lung uptake of 201Tl in bronchopulmonary diseases]

201Tl scintigraphy was performed in various bronchopulmonary diseases. Applying semiquantitative and visual assessments of grade of 201Tl was observed in various broncho-pulmonary diseases with multiple or numerous abnormal shadows in the lung fields, and obvious lung uptake was also shown even in some cases with few or no abnormal shadows. Positive results of moderate and marked lung uptake of 201Tl more than 60.0% were obtained in diffuse interstitial pneumonia, hypersensitivity pneumonitis, silicosis, the disseminated type of pulmonary tuberculosis and primary lung cancer. The ratio of radioactivity of the lung (maximum) to the upper mediastinum was 1.04 +/- 0.24 in healthy controls, and more than 2.0 in diffuse interstitial pneumonia, hypersensitivity pneumonitis and silicosis. The ratio of radioactivity of the right lung to the administered dose of 201Tl was 1.5 +/- 0.9% in healthy controls, and more than 3.0% in diffuse interstitial pneumonia, silicosis, the disseminated type of pulmonary tuberculosis and primary lung cancer. Lung uptake of 201Tl was diffuse, homogeneous and marked in diffuse interstitial pneumonia and hypersensitivity pneumonitis, while it was scattered and slight in chronic obstructive lung diseases. 201Tl scintigraphy seems to be useful for detecting interstitial disorders of the lung including edema, inflammatory and granulomatous changes, especially in cases with slightly abnormal or normal chest X-ray films.