[Ventilation-perfusion-lungscintigraphy using PET and 68Ga-labeled radiopharmaceuticals]

Imaging of lung perfusion with positron emission tomography (PET) is already possible with 68Ga labeled denaturized albumin. The purpose of our study was to produce and test a 68Ga labeled aerosol (Galligas®) for ventilation and 68Ga labeled albumin particles (microspheres) for perfusion imaging with PET.

Galligas was produced by simmering and burning generator eluted 68Ga solution (100 MBq/0.1 ml) in an ordinary technegas generator. Fifteen patients with suspicion on pulmonary embolism underwent PET/CT (Biograph 16) after inhalation of Galligas and application of 68Ga labeled microspheres. A low dose CT was acquired for attenuation correction (AC). Images were reconstructed with and without AC. The inhaled activity was calculated compared to the activity injected.

Inhaled radioaerosol Galligas demonstrated typical distribution as known from 99mTc-labeled technegas with homogeneous distribution in lung without hilar deposits. Attenuation corrected images resulted in artefacts in the lung base. Therefore, non-corrected images were used for making the results. Three out of fifteen patients showed a deficient perfusion whereas ventilation was normal corresponding to pulmonary embolism.

Lung scintigraphy with PET is feasible. Galligas is simple to produce (analogously to technegas). 68Ga labeled microspheres are available. The method is applicable to daily routine and rendered clinically relevant informations.