PET lung ventilation scanning with Gallium-68 aerosol (Gallgas) versus Technegas SPECT in patients with obstructive lung disease: A feasibility study

Objectives It is well known that Technegas SPECT images are of good quality with appropriate alveolar retention and lack of hiliar deposits. The objective of this study was to assess the feasibility of performing PET-CT lung ventilation imaging with Gallium-68 aerosol nanoparticles (Gallgas) in patients with chronic obstructive pulmonary lung disease (COPD) in comparison to Technegas.

Methods Six studies were performed to three patients with moderate to severe COPD after the administration of an estimated mean inhaled activity of 27 MBq for Gallgas (n=3) and 70 MBq for Technegas (n=3). Eluate from a Ge-68/Ga-68 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 of 3 min each with a 64-slice multidetector component. Low-dose CT was performed without i.v. contrast and PET images were reconstructed using an iterative OSEM algorithm with TOF correction.

Results The accuracy of both techniques to detect regions of alveolar hypoventilation was similar in all patients, without hot spot depositions. Non-segmental defects were similar in number and distribution for SPECT and PET. However, ventilation distribution on PET images were more detailed and showed more variation than those on SPECT.

Conclusions The results of this exploratory study suggest that Gallgas PET-CT may be a suitable alternative to conventional Technegas SPECT scanning for the evaluation of lung ventilation in patients with COPD. Additionally, PET high-resolution images have the potential of performing a better regional quantitation of lung function