Comparison of treadmill exercise versus dipyridamole stress with myocardial perfusion imaging using rubidium-82 positron emission tomography

OBJECTIVES This study assessed the feasibility of treadmill exercise rubidium-82 (Rb-82) positron emission tomography (PET) and compared image quality and diagnostic content with dipyridamole Rb-82 PET in patients referred for evaluation of coronary artery disease (CAD). BACKGROUND Dipyridamole stress Rb-82 PET myocardial perfusion imaging (MPI) is an accurate imaging modality, used to diagnose CAD and determine prognosis. Although pharmacologic stress is used routinely, exercise treadmill stress may be an alternative and provide clinical information helpful to decision making, particularly for patients unwilling or unable to tolerate pharmacologic stress. METHODS Fifty patients (mean age, 60 +/- 10 years; 47 men) underwent treadmill exercise and dipyridamole Rb-82 PET. Images were assessed: 1) qualitatively using a 17-segment model and a semiquantitative visual score on a five-point scale and with calculation of summed stress score (SSS), summed rest score (SRS), and summed difference score (SDS); and 2) quantitatively with a 70% threshold for abnormal perfusion and expressed as extent of abnormal perfusion (% left ventricular). RESULTS Treadmill exercise was preferred by 74% of patients (37 of 50, p < 0.001). The exercise and dipyridamole Rb-82 PET summed scores and quantitative extent of abnormal perfusion were very similar and highly, correlated. Results of Bland-Altman analysis showed no significant bias. Image quality was superior with exercise stress with greater myocardial uptake and higher target to background ratios. CONCLUSIONS Treadmill exercise Rb-82 PET is feasible and provides imaging results of similar diagnostic content and superior image quality compared with dipyridamole stress. Treadmill exercise is a reasonable alternative to pharmacologic stress with Rb-82 PET MPI.