Tracheobronchial mucociliary clearance and alveolar epithelial permeability measured by PET with 18FDG powder

Tracheobronchial mucociliary clearance and alveolar permeability were measured with positron emission tomography using a water-soluble dry aerosol, sodium-N-acetyl-neuraminate tagged with 2-deoxy-2-[18F]fluoro-D-glucose (18FDG powder). Five normal volunteers inhaled 1.5-2.0 mCi of FDG powder by a single deep breath. The distribution of radioactivity, measured by scanning during a period of 120 min, showed that the 18FDG powder deposition progressed from the central airways to the peripheral alveolar areas. In the tracheobronchial system the radioactivity decreased to 24% of the initial deposition at 60 min. In the peripheral alveolar area, where absorption into blood or lymphatic flow crossing the epithelial layer represents a unique mechanism of clearance for water-soluble 18FDG powder, alveolar radioactivity decreased slowly to approximately 70% of the initial deposition at 60 min after inhalation. Positron emission tomography using 18FDG powder provides a regional evaluation of both mucociliary transport in the tracheobronchial system and epithelial permeability in the alveolar area.