Usefulness of respiratory-gated 18F-FDG PET/CT scan protocol in patients having positive myocardial 18F-FDG uptake

OBJECTIVE: The aim of this study were to estimate the influence of respiratory movement on the fluorine-18-fluorodeoxyglucose (F-FDG) PET/computed tomography (CT) imaging of patients having positive myocardial F-FDG uptake and to demonstrate an adequate respiratory-gated F-FDG PET/CT scan protocol. MATERIALS AND METHODS: An anthropomorphic chest phantom containing a cardiac ventricle phantom was filled with an fluorine-18 solution and scanned in both a nonmoving state and a moving state with respiratory gating. In the nonmoving state, PET images were acquired in static mode (static PET), whereas in the moving state, PET images were acquired in a nongated mode (nongated PET), and in a gated mode (gated PET). The gated PET images were divided into 2-10 phases. The standardized uptake value (SUV)nongated ratio and SUVgated ratio (SUVnongated ratio or SUVgated ratio=SUVmean of nongated PET or gated PET/SUVmean of static PET) were calculated. In addition, nongated PET images and gated PET images were created from 12 sets of respiratory-gated clinical F-FDG PET/CT acquisitions. The clinical 12 gated PET data were divided into 2-8 phases. We measured SUVmax of cardiac volume data at each number of phases. RESULTS: In dividing into more than three phases, the SUVgated ratio remarkably improved. In dividing into more than five phases, rate of SUVmax improvement from nongated PET showed 5% in the analysis of clinical data. CONCLUSION: For a F-FDG PET/CT scan for patients with having positive myocardial F-FDG uptake, a respiratory-gated PET protocol divided into five phases is recommended, to minimize the influence of internal motion on cardiac accumulation.