A Noninvasive [99mTc]DTPA SPECT/CT Imaging Methodology as a Measure of Lung Permeability in a Guinea Pig Model of COPD

Purpose The purposes of this study are (1) to develop an efficient aerosol inhalation system for the delivery of [ 99m Tc]DTPA aerosol into guinea pig airways with high uniformity for measuring lung clearance using SPECT/CT imaging, as a measure of lung permeability, and (2) to use [ 99m Tc]DTPA studies in guinea pig model of chronic obstructive pulmonary disease (COPD) to determine its usefulness in studying pathogenesis of COPD. Procedure We developed an aerosol delivery system and single-photon emission computed tomography (SPECT) imaging method to measure the pulmonary clearance rate in anesthetized guinea pigs. In this system, an 830-cc rebreather exposure chamber was filled with oxygen immediately before a 5 min [ 99m Tc]DTPA (4–5 mCi/mL) aerosol exposure. The rebreather included a top mounted AeroNeb micro pump nebulizer, a nose-only exposure tube, and rear evacuation port. An 830-cc rebreather exposure chamber was filled with oxygen immediately before 5 min [ 99m Tc]DTPA (4 ∼ 5 mCi/mL) aerosol exposure. One control and one cigarette smoking group were studied. Results Images showed high and uniform lung deposition and the mean clearance rate was increased by 37% in smoking group. Conclusions The combined SPECT/CT imaging method developed here can be used for serial evaluation of lung function and its response to drug therapy in guinea pig model of COPD.