[Pulmonary nuclear medicine].

Pulmonary nuclear medicine dates back to Knipping and West in the late 1950's but practically starts with the successful production of 131I-MAA by GV Taplin in 1963. Not only is the diagnosis of pulmonary embolism greatly facilitated by using 131I-MAA but also studies of regional lung function have made rapid progress. Radioactive gas and aerosol inhalation have been used to study ventilation distribution in the lungs. Using nuclear medicine technology regional hypoxic vasoconstriction was found to play a great role in regulating regional perfusion distribution in the lungs. Ventilation and perfusion mismatch and match indicate organic lung diseases and pulmonary vascular diseases, respectively. Aerosol deposition patterns in the lungs are helpful in the differential diagnosis of chronic obstructive lung diseases (COPD). Technigas is an ultrafine aerosol which is probably more useful for ventilation studies than conventional aerosols produced by either a jet or an ultrasonic nebulizer. Besides respiratory lung function pulmonary nuclear medicine techniques have made it possible to study nonrespiratory lung function. One is mucociliary clearance mechanisms. They can be studied by using a nonabsorbable aerosol like 99mTc-albumin. Dynamic mucociliary clearance function can be visualized in vivo by radioaerosol inhalation lung cine-scintigraphy. Four abnormal mucociliary transport patterns were discernible in COPD. An objective evaluation of a drug effect on mucociliary transport is feasible. Detailed quantitative analysis of mucociliary clearance is also possible by computer techniques. Pulmonary epithelial permeability is studied following inhalation of 99mTc-DTPA aerosol. Inhaled 99mTc-DTPA disappears from the lungs more rapidly in smokers and patients with interstitial lung diseases. Nuclear medicine has great potential to elucidate other functions of the lung which are still not defined yet by the present knowledge of lung function.