Continuous aerosol inhalation scintigraphy in the evaluation of early and advanced airways obstruction.

By means of continuous lung imaging, regional mucociliary removal rates of inhaled 99mTc-labeled human serum albumin minimicrospheres were determined over upper, middle, lower, central, and peripheral anterior lung areas. Additionally, an index was employed for analysis of initial pulmonary radioaerosol distribution in order to quantify the site of particle deposition in various degrees of airways obstruction. The study involved 15 volunteer healthy subjects, 20 asymptomatic smokers with early small airways obstruction, and 30 patients with advanced chronic obstruction of large airways. The healthy group showed evenly distributed lung activity and (normal) clearance rates consistent with data from earlier work. While most uneven lung aerosol distribution was seen in the patients with large airways obstruction, slowest mucociliary clearance velocity was encountered in the smokers with small airways dysfunction. The aerosol technique, if carefully controlled, can be a useful supplement to pulmonary ventilatory function testing, showing reduction of bronchial mucous velocity to be one of the earliest signs of functional impairment in asymptomatic cigarette smokers.