Scintigraphy with 201TlCl and 197HgCl2 was performed in 323 patients with various respiratory diseases. Diffuse, marked bilateral lung uptake of 201Tl or 197Hg was demonstrated in 2 of 3 cases with hypersensitivity pneumonitis, 26 of 29 cases with silicosis and 28 of 29 cases with diffuse interstitial pneumonia, but in diffuse panbronchiolitis, chronic bronchitis and pulmonary emphysema, only slight lung uptake or negative results were obtained in most cases. In diffuse interstitial pneumonia, no close correlation was observed between the grade of the lung uptake and the various clinical findings such as fever, cough, rales, ESR, S-LDH, α1-globulin, %VC, PaO2 and so on. With regard to roentgenological findings, marked lung uptake was observed in cases not only with reticulonodular shadows but also those with ring shadows and those without any shadows. Concerning the microscopic findings of lung biopsy specimens, marked uptake was observed in cases with slight interstitial fibrosis as well as infiltration of mononuclear cells. The right ventricle was visualized in 13 of 19 cases (68.4%) with diffuse interstitial pneumonia. Lung scintigraphy with 201Tl chloride is non-invasive and seems a more sensitive indicator of diffuse intersitial changes such as inflammatory disorders than the clinical findings, chest X-ray and so on.
