Inhalation lung imaging with radioactive aerosols and gases

Krypton lung-imaging is considered the ventilation procedure of choice when it is available. Aerosol and krypton wash-in images both reveal regional abnormalities of ventilation, but the aerosol images also disclose evidence of major airways disease. Xenon wash-out images are probably the most sensitive indicators of regional abnormalities of ventilation and/or small airways obstruction, whereas xenon wash-in images are far less sensitive and may be frequently misinterpreted. The Tc-DTPA aerosol inhalation procedure is perferred over xenon and krypton ventilation imaging for routine use immediately after a perfusion examination in pulmonary embolism suspects. This combined method provides the referring physician with the necessary diagnostic information quickly and with around-the-clock availability. In our opinion, this new aerosol procedure deserves wider application in the diagnosis and management of pulmonary disease. Lung imaging procedures, performed after th inhalation of 99mTechnetium labeled aerosols, 133Xenon and and 81mKrypton gases, were used to visualize the sites of airway obstruction and regional abnormalities of ventilatory function in normal volunteers, patients with obstructive airway disease and pulmonary embolism suspects. This chapter presents intercomparisons of these three methods regarding their functional significance, diagnostic merits, and limitations. A new nebulizer-radioaerosol delivery system is described. Test agent kits are inexpensive and readily available for on site assembly. Currently, we consider radioaerosol imaging in multiple views as more informative and suitable for routine use than xenon methods to detect regional abnormalities of the airways and ventilatory function. The krypton procedure is preferred in pulmonary embolism suspects because it requires far less patient cooperation than the xenon and aerosol methods and the lung images disclose regional ventilatory impairment quickly and accurately. However, krypton gas is cyclotron-produced and not yet commercially available.