Clinical Study Of Myocardial Ischemia And Myocardial Glucose Metabolism Imaging

LI Jia, DOU Ke-fei, YANG Min-fu, HE Zuo-xiang. Department of Cardiology, Cardiovascular Institute and FuWai Hospital,Chinese Academy ofMedical Sciences and PekingUnion MedicalCollege, Beijing, China;[Objective]:To explore whether the increasing ischemic myocardial 18F-FDG uptake can persist for24h or more long time after24 hours of exercise-induced myocardial ischemia.[Method]:24 patients with strong clinical suggestion of CAD underwent exercise "Tc-sestamibi myocardial perfusionimagingand 18F-FDGmetabolismimaging.24 hours after the episode of exercise, the patients were reinjected 18F-FDG and underwent 18F-FDG imaging at rest. All patients underwent coronary angiograph within 1 week.[Result]:Coronary angiograph showed that 20 patients had greater than or equal to 50% luminal narrowing in at least one coronary vessels. On the exercise 18F-FDG imaging,15(83%) patients showed increased regional 18F-FDG uptake, but only 11 patients (61%) showed perfusion abnormalities on 99mTc-sestamibi imaging. On the rest 18F-FDG imagingafter 24 hours of the exercising,7 patients(46%) of the 15 patients who showed increased regional 18F-FDG uptake on exercise imaging showedpersistent 18F-FDG uptake.[Conclusion]:myocardial ischemia by exercise can increase myocardial ischemia 18F-FDG uptake. In some patients, the increasingof myocardial ischemia 18F-FDG uptake can be persisted to 24 hoursafterischemia.[Objective]:Increased myocardial glucose metabolism occurs with the onset of myocardial ischemia and may persist even after the restoration of blood flow, termed as’ischemic memory’. Previous studies have demonstrated that 18F-FDG is a sensitive marker of myocardial ischemia and may have potential utility in diagnosing recent myocardial ischemia. This study aimed to explore the value of 18F-FDG PET/CT in diagnosing recent myocardial ischemia.[Methods]:Thirty-four patients (17 males, mean age 59±6 years) with suspected UA were prospectively recruited. Resting myocardial 18F-FDG PET/CT imaging was performed 21±9 hours (2-46 hours) after the latest onset of angina pectoris. Resting or exercise myocardial perfusion imaging (MPI) as well as coronary angiography were performed.’Focal’or’focal on diffuse’ myocardial 18F-FDG uptake was defined as abnormal, whereas other patterns of myocardial uptake including’focal’uptake on the basal segments were considered as normal. The final diagnosis of recent myocardial ischemia was based on a comprehensive analysis of electrocardiography, MPI, and coronary angiography.[Results]:Of 21 patients with a final diagnosis of UA,18 had increased 18F-FDG uptake (sensitivity 85.7%), whereas, of 13 patients without UA, only 1 had abnormal 18F-FDG uptake (specificity 92.3%). The sensitivity of resting 18F-FDG imaging was higher than that of resting MPI (85.7% vs.52.4%, P=0.016). Moreover,6 patients with only exercise-induced ischemia showed abnormal 18F-FDG uptake at rest.[Conclusion]:This pilot study demonstrated that resting 18F-FDG PET/CT imaging is an accurate and sensitive technique for the identification of recent myocardial ischemia.