Mapping of PET-measured aerosol deposition: a comparison study

Three-dimensional positron emission tomography (PET) can be used to assess the spatial distribution of inhaled aerosols, and with lung models of airway parameters this data can be converted into aerosol deposition information for each airway generation. Two alternative methods for extracting this generational data, the analytical and the arithmetic reconstruction technique (ART), are investigated in conjunction with two different airway branching models, monopodial and dichotomous, to determine pulmonary deposition in a canine model. All solutions revealed two regions with high deposition: the first 10 generations past the trachea (1-10) and the deepest lung generations (18-23). Post-imaging autoradiographic images were in agreement with the deposition pattern in the larger airway generations (1-10). In comparing the different techniques, the dichotomous lung model yielded large variance in mapped activity but similar concentrations because of variation in generation volumes, while ART showed a greater ability to discern small differences in deposition patterns between subjects.