Technique for aerosol deposition restricted to the nose in beagle dogs.

A method was developed for exposing the nasal cavity of beagle dogs to a radiolabeled aerosol without exposure of the remainder of the respiratory tract. Deposition efficiency, using a test aerosol of 2.0-micron particles of 99mTc-sulfur colloid delivered to the nose, was 15 +/- 2% (mean +/- SE) of inhaled activity. Gamma camera imaging showed that maximum deposition occurred in the anterior third of the nasal cavity, which contained 78 +/- 4% (mean +/- SE) of the total deposited radioactivity. The middle-third of the nasal cavity received 13 +/- 3% and the posterior third 9 +/- 2% of the deposited radioactivity. Aerosol deposition in regions of the respiratory tract below the larynx was not detectable.