Inhalation Lung Scanning Evaluation-Radioaerosol Versus Radioxenon Techniques

¹ Pulmonary Trainee, National Heart Institute, National Institutes of Health (HE5655)
² Pulmonary Division, Department of Medicine, and the Radioisotope Unit of the Ceorgetown University Medical School, Washington, D.C.
³ Career Development Investigator of the National Heart Institute, National Institutes of Health; Associate Professor of Medicine, University of California, San Diego School of Medicine

The routine study of regional ventilation of the lungs has been hampered by the lack of safe, simple and accurate methods. Radioisotope techniques have made possible the development of such methods. Two varieties of radioactive scanning have been used: radiolabelled particulate material, and radioactive inert gases. We have performed scans using both inhaled technetium-99m albuminate particles and xenon 133 gas. Normal subjects and patients with pulmonary disease were studied. Particle inhalation in normal controls revealed adequate peripheral filling, although upper airway and gastrointestinal deposition occurred. In patients with pulmonary disease, however, underventilated zones of lung appeared totally unventilated with particle scans, while those with ¹³³Xe gas reflected ventilation disturbances more accurately. Further, a dynamic visualization of ventilation could be obtained using ¹³³Xe, while scans with ^99mTc albuminate indicated the cumulative result of several minutes of positive pressure breathing. It is concluded that both methods can offer important information, but each has its own limitations and advantages which should recognized. Valuable insights into respiratory physiology and pathogenesis of pulmonary diseases can be obtained from these new techniques.