Ga-68 EDTA aerosols in evaluation of inhaled-particle deposition and clearance of obstructive pulmonary diseases: A pilot prospective study compared with Galligas.

Purpose 68-gallium (Ga-68) ethylenediaminetetraacetic acid (EDTA) aerosols and Galligas were compared in evaluation of inhaled-particle deposition and clearance in volunteers with or without obstructive pulmonary diseases. Methods Nonsmoking healthy volunteers, healthy smokers, asthma patients and patients with chronic obstructive pulmonary disease (COPD) were recruited to undergo the dynamic lung ventilation positron emission tomography/computerized tomography (PET/CT) scans within two consecutive days. The inhaled particles were Ga-68-labelled carbon nanoparticles (Galligas, 30-60 nm in size) and Ga-68-labelled EDTA aerosols (1-2 μm in size), respectively. The volunteers' lung function parameters were measured for comparison. Results Central deposition and inhomogeneity of both tracers were negatively correlated with lung function parameters, including the ratio of forced expiratory volume at 1 second to forced vital capacity (FEV1 /FVC). The central or hilum deposition of Galligas, but not 68-gallium (Ga-68) EDTA, was negatively correlated with the maximal expiratory flow at 25%, 50% and 75% of the forced vital capacity. Compared with Galligas, Ga-68 EDTA aerosols were more concentrated in the central region in all groups except for the healthy nonsmokers. Ventilation inhomogeneity was more evident when using Ga-68 EDTA aerosols, especially in patients with COPD and asthma patients. In the healthy smokers, the central region accumulated more Ga-68 EDTA at 30 minutes after inhalation than immediately after inhalation. Ga-68 EDTA cleared faster in lungs than Galligas. Conclusions Both Galligas and Ga-68 EDTA aerosols can be used for PET/CT lung ventilation scan. However, Ga-68 EDTA aerosols showed more advantages in diagnosis and evaluation of obstructive airway diseases by revealing the inhaled-particle deposition and clearance.