Use of prospective gating in PET/CT imaging of lung nodules

Objectives Prospective reconstruction respiratory gated PET/CT improves small lesion detectability, minimizes motion artifact and has less radiation exposure then Retrospective reconstruction

Methods 30 lung cancer patients were done on a 16 slice Time of Flight PET/CT scanner. Patients were scanned supine with respiratory bellows around their chest. All patients were scanned in two bed position, covering the lung field, approximately fourteen minutes. CT was gated with a bellow device and was processed at 40-60% of maximum expiration. PET data was acquired at 40-60% of maximum expiration reconstructed at 3 iterations and 33 subsets per manufactures guidelines

Results The gated and non-gated images of both the PET and the CT were compared in all three planes. Sizes of the lesions were drawn on both sets of data for comparison. Activity on the gated images was higher and there was better image resolution on the gated compared to the non-gated.

Conclusions Respiratory gated provides an easy way to see smaller lesions, which allows for more accurate diagnosis of lung lesions. Prospective gating is equal in reconstruction quality as retrospective with out the higher radiation exposure to the patient