Early Clinical Applications of Lung Scintiscanning

Abstract

Scintiscanning of the lungs offers a new approach to the diagnosis of pulmonary disease. Denatured iodinated human serum albumin particles, 10 to 50 microns in diameter, are obtained by adjusting the pH, time, and temperature of incubation (1, 2). Following their intravenous injection, these particles are temporarily delayed in the pulmonary arterial tree (3–5). After one hour, radioactivity increases in the liver and spleen and diminishes over the lung, supporting the thesis that the particles are broken down to smaller aggregates which then localize in the liver and spleen. At twenty-four hours there is little radioactivity over the lungs or abdomen. The technic was found to be useful in outlining experimentally produced pulmonary infarcts in dogs (4, 5). This report contains our initial clinical experience in man. Ten pulmonary scans were performed on 9 patients with various diagnoses. The results are presented in Table I. There were no untoward reactions and the patients noted no unusual feeling attributable to the compound injection. Case I: A 59-year-old male presented with weight loss, cough, and chest pain. A roentgenogram (Fig. 1) demonstrated a mass in the upper lobe of the right lung. A postero-anterior lung scan (Fig. 2) performed immediately after compound injection showed no radioactivity in the tumor region. An exploratory thoracotomy revealed an unresectable poorly differentiated squamous-cell carcinoma of the right upper lobe. The lack of radioactivity in the tumor area suggests that the neoplasm is supplied by bronchial circulation and/or is compromising the pulmonary circulation in the region. Case II: A 68-year-old male had fever and obstructive jaundice. The chest film (Fig. 3) demonstrated nodular and diffuse densities radiating from the hilar regions, more prominent on the right side. An anteroposterior pulmonary scan immediately after compound injection showed two wedge-shaped areas of diminished activity (Fig. 4). These areas were revealed at necropsy thirty-six hours later to be ischemic infarcts. Diffuse bronchopneumonia was also present. Pancreatic carcinoma with hepatic metastases accounted for the patient's obstructive jaundice. Clinical application has demonstrated that in man, as in the dog with the experimentally produced pulmonary infarcts, lung scintiscanning can detect an obstruction of the pulmonary circulation as soon as it is established. Pulmonary angiography can also give an immediate positive demonstration (6), but is technically more difficult and time-consuming. Lung scanning requires no patient preparation-and the scan is performed immediately after compound injection. In acute cor pulmonale the procedure is theoretically hazardous due to the temporary small additional mechanical impediment to pulmonary blood flow.