Reply: The Rediscovery of Galligas

REPLY: We thank Drs. Kotzerke and Zöphel for their comments regarding our study (1) on ⁶⁸GaCl₃-labeled pseudogas (“Gallgas”) as a marker of ventilation distribution. We are sorry for not having included their correspondence (2) and report (3) on ⁶⁸Ga for assessing ventilation–perfusion distribution. Both were published after the submission of our manuscript, but an update by us should have revealed their letter from early 2010. However, more important is the full agreement between us and Dr. Kotzerke and coworkers that ⁶⁸Ga can be a useful tracer for studying respiratory function. We also noticed that our studies complement each other. We have done animal experiments under more controlled conditions and have made comparisons with the present reference technique (Technegas), whereas Dr. Kotzerke and coworkers have studied patients with suspected pulmonary emboli, relating their findings to what historically is known as a typical pattern for pulmonary emboli.

We hope that our studies, taken together, will further the interest in using gallium tracers for respiratory function measurements, with the improvement in resolution over traditional technetium-labeled markers and the γ-camera.

• © 2011 by Society of Nuclear Medicine