Myocardial 18F-FDG uptake after exercise-induced myocardial ischemia in patients with coronary artery disease

Abstract

We have recently demonstrated the potential of 18F-FDG as an imaging marker of myocardial ischemia if injected at peak exercise. However, how long increased 18F-FDG uptake can be observed after an episode of exercise-induced myocardial ischemia is not known. We performed the current study to determine whether increased regional myocardial 18F-FDG uptake at exercise in patients with coronary artery disease (CAD) persists on rest imaging (24 h later), after an episode of exercise-induced myocardial ischemia. Methods: Twenty-four patients with suspected CAD underwent exercise 99mTc-sestamibi and 18F-FDG imaging. Repeated 18F-FDG imaging was performed 24 h after exercise imaging, after an injection of a second dose of 18F-FDGat rest in 20 patients. Perfusion imaging with 99mTc-sestamibi was simultaneously performed with 18F-FDG imaging. All patients underwent coronary angiography. Results: Eighteen patients had greater than or equal to 70% luminal narrowing of 1 or more coronary vessels. Fifteen patients (83%) showed increased regional 18F-FDG uptake on exercise imaging, but only 11 patients (61%) had perfusion abnormalities. Of these 15 patients with increased regional 18F-FDG uptake on exercise imaging, 8 (53%) had no discernible 18F-FDG uptake, 5 (33%) had decreased 18F-FDG uptake, and only 2 (13%) had persistent 18F-FDG uptake on rest 18F-FDG images. The summed 18F-FDG uptake score significantly decreased, from 14.4 ± 10.3 at exercise to 6.7 ± 9.2 at rest (P = 0.01). Patients with persistent 18F-FDG uptake at rest had more 18F-FDG uptake and lower peak rate-pressure product at exercise, compared with patients with no residual 18F-FDG uptake at rest. Conclusion: Exercise-induced regional myocardial 18F-FDG uptake is highly specific and sensitive for exercise-induced myocardial ischemia. Regional myocardial 18F-FDG uptake may persist 24 h after an episode of exercise-induced myocardial ischemia in some patients. Copyright © 2008 by the Society of Nuclear Medicine, Inc.