Performance Evaluation of Amplitude and Phase Respiratory Gating Methods on Continuous-Bed-Motion Whole-Body PET Studies

Positron emission tomography (PET) scanners with the feature of continuous-bed-motion (CBM) that allows efficient whole-body dynamic scans and customized imaging protocols have been made commercially available in recent years. As the bed motion has to be reasonably slow in order to achieve sufficient count statistics, the blurring effect induced by respiratory motion is inevitable, and adequate gating methods should be applied. The aim of this study is to identify a relatively reliable gating method for CBM whole-body scans with respect to breathing pattern variability. Two methods: 1) equal amplitude gating (EAG) and 2) phase gating (PG) initially developed for the single-bed imaging protocol are evaluated using CBM data for subjects with a regular breathing pattern, irregular breathing pattern with baseline shift, and irregular breathing pattern with prolonged end expiration. The potential influence of the scan duration on the performance of the applied gating methods is taken into account as well. Based on the results, we suggest that the PG method is relatively reliable for all studied breathing patterns, while the EAG method could introduce severe artifacts in the presence of the baseline shift.