Comparison of ventilation with Gallium-68 aerosol (Gallgas) and Technegas in patients with obstructive lung disease

Objectives The aim of this study was to perform an intraindividual comparison of ventilation in chronic obstructive pulmonary lung disease (COPD) patients. We have compared 68Gallium aerosol nanoparticles (Gallgas) using PET/CT to 99mTechnegas SPECT.

Methods Twenty studies were performed in ten patients with moderate to severe COPD after administration of an estimated mean inhaled activity of 27 MBq for Gallgas (n=10) and 70 MBq Technegas (n=10). Eluate from a 68Ge/68Ga generator was purified and concentrated by a QMA cartridge before production of Gallgas nanoparticles. Ventilation SPECT was performed acquiring 120 images in 360°, 15-s per step. Gallgas PET-CT was performed using 2 or 3 bed positions, 3 min each with a 64-slice multidetector component. Low-dose CT was performed for attenuation correction. PET images were reconstructed using an iterative OSEM algorithm with TOF correction.

Results Gallgas and Technegas were able to detect regions of alveolar hypoventilation in all patients. Both tracers discriminated the same number and topography of non segmental defects, but Gallgas PET images gave a more detailed information of the distribution of the ventilation.

Conclusions Gallgas PET-CT and Technegas SPECT scanning can be used for the evaluation of lung ventilation in patients with COPD. Gallgas allowed a better spatial discrimination of the tracer distribution than Technegas. This fact can potentially be used for regional quantitation of lung ventilation.

Research Support PROINBIO, CUDIM