Compensating for patient respiration in PET/CT imaging with the registered and summed phases (RASP) procedure

PET/CT imaging has introduced new challenges in accurate quantitation of lung nodules due to respiratory motion and mismatches in CT-based attenuation correction (CTAC). We used Monte Carlo simulations to investigate how respiratory-correlated CTAC can be optimized to account for mis-registration between the AC data and the PET data due to respiratory motion. This step also allows compensating for increased emission noise in respiratory-gated PET images by non-rigid image registration of the CTAC phases. These registration parameters are then applied to the attenuation-corrected PET phase images, which are then summed to reduce noise. A significant increase in the final PET SNR is demonstrated.