Airway identification within planar gamma camera images using computer models of lung morphology

Quantification of inhaled aerosols by planar gamma scintigraphy could be improved if a more comprehensive assessment of aerosol distribution patterns among lung airways were obtained. The analysis of planar scans can be quite subjective because of overlaying of small, peripheral airways with large, conducting airways. Herein, a computer modeling technique of the three-dimensional (3-D) branching structure of human lung airways was applied to assist in the interpretation of planar gamma camera images. Airway dimensions were derived from morphometric data, and lung boundaries were formulated from scintigraphy protocols. Central, intermediate, and peripheral regions were superimposed on a planar view of the 3-D simulations, and airways were then tabulated by type, number, surface area, and volume in each respective region. These findings indicate that the central region, for example, consists mostly of alveolated airways. Specifically, it was found that alveolated airways comprise over 99% of the total number of airways, over 95% of the total airway surface area, and approximately 80% of the total airway volume in the central region. The computer simulations are designed to serve as templates that can assist in the interpretation of aerosol deposition data from scintigraphy images.