Direct Imaging of Exercise-induced Myocardial Ischemia with Fluorine-18-labeled Deoxyglucose and Tc-99m-sestamibi in Coronary Artery Disease

Background: Scintigraphic myocardial perfusion imaging is the most widely used noninvasive modality for the detection of coronary artery disease (CAD). A technique for direct imaging of exercise-induced myocardial ischemia is highly desirable and preferable over perfusion imaging but is presently unavailable. We evaluated the feasibility and diagnostic accuracy of direct imaging of exercise-induced myocardial ischemia with fluorine-18-2-deoxyglucose (18FDG).

Methods And Results: Twenty-six patients with known or suspected CAD and no prior myocardial infarction underwent simultaneous myocardial perfusion and ischemia imaging after the intravenous injection of Tc-99m-sestamibi (99mTc-sestamibi) and 18FDG at peak exercise. Rest perfusion imaging was carried out separately. All patients underwent coronary angiography. Exercise 18FDG myocardial images were compared with exercise-rest 99mTc-sestamibi images and coronary angiography. Of 22 patients with > or =50% narrowing of > or =1 coronary arteries, 18 had perfusion abnormalities (sensitivity 82%) whereas 20 had abnormal myocardial 18FDG uptake (sensitivity 91%, P=NS). Perfusion abnormalities were seen in myocardial segments corresponding to 25 vascular territories of a total of 51 vessels with > or =50% luminal narrowing in 22 patients (sensitivity 49%), whereas increased 18FDG uptake was seen in 34 vascular territories (sensitivity 67%, P=0.008). 18FDG images were of high quality and easy to interpret but required simultaneous perfusion images for localizing abnormal myocardial 18FDG uptake.

Conclusions: Exercise-induced myocardial ischemia can be imaged directly with 18FDG. Combined exercise 18FDG-99mTc-sestamibi imaging provides a better assessment of exercise-induced myocardial ischemia compared with exercise-rest perfusion imaging. Direct ischemia imaging eliminates some of the limitations of presently used myocardial perfusion imaging. Large-scale clinical studies are warranted.