ASSESSMENT OF CORONARY RESERVE IN MAN - COMPARISON BETWEEN POSITRON EMISSION TOMOGRAPHY WITH OXYGEN-15-LABELED WATER AND INTRACORONARY DOPPLER TECHNIQUE

This study compared positron emission tomography (PET) using oxygen-15 -labeled water for measurement of coronary reserve with intracoronary Doppler in patients with left anterior descending artery stenosis and patients with no coronary lesion and a coronary reserve 3 as assessed by the invasive technique To determine whether PET measurement of coro nary reserve is altered by partial volume effect, patients with left v entricular dysfunction due to idiopathic cardiomyopathy were studied w ith both techniques. Direct ultrasonic measurement of coronary reserve was performed the day prior to the PET study: a Doppler catheter was placed in the proximal left anterior descending artery; mean velocity was recorded at baseline and after dipyridamole administration. Using a time-of-flight PET system, patients underwent: (1) an intravenous bo lus of oxygen-15-labeled water at baseline and 4 to 6 min after intrav enous infusion of dipyridamole using the same protocol as for Doppler study and (2) a F-18-fluorodeoxyglucose (FDG) myocardial imaging. Oxyg en-1 5 time-activity curves were recorded in myocardial regions of int erest (ROIs) drawn on a static FDG image Using the left ventricular ti me-activity curve as an input function, a standard model with a single -tissue compartment was fitted to the PET data; myocardial blood flow was estimated as the blood-to-tissue transfer rate constant. Coronary reserve measured by PET was well correlated with that measured by intr acoronary Doppler (r = 0.98, p < 0.001 for global population). This PE T method is an accurate and reliable tool to noninvasively measure cor onary reserve in patients, even in those with left ventricular dysfunc tion.