Feasibility of myocardial perfusion imaging with half the radiation dose in obese patients using ordered-subset expectation maximization with resolution recovery software

BackgroundWe previously described the feasibility of myocardial perfusion imaging (MPI) with nearly half the radiation dose using ordered-subset expectation maximization with resolution recovery (OSEM-RR) processing. This study sought to determine if the findings can be expanded to obese patients.MethodsFifty obese patients (>100 kg) referred for MPI underwent stress-rest or rest-stress studies with a half dose of Tc-99m sestamibi in a 1-day protocol using OSEM-RR processing. Image quality and clinical results were compared with matched patients (by age, sex, weight, presence/probability of coronary artery disease) evaluated with standard “full-dose” Tc-99m sestamibi, mostly in a 2-day protocol. Dose activities were adjusted individually by weight.ResultsMean Tc-99m activity was 33.4 ± 13.9 mCi in the half-dose group and 60 ± 10 mCi in the full-dose group (P < .0001). Respective mean effective doses per study were 10 ± 4 and 18 ± 3 mSv (P < .0001). Overall image quality was good-to-excellent in 94% of the half-dose group and 80% of the full-dose group (P < .045). There was no between-group difference in rate or size of ischemia or infarction, except for stress left ventricular ejection fraction.ConclusionsMPI with half the radiation dose is feasible in obese patients. Image quality is better than for full-dose MPI, and the procedure can be performed in 1 day.