Washout of 82Rb as a marker of impaired tissue integrity, obtained by list-mode cardiac PET/CT: relationship with perfusion/metabolism patterns of myocardial viability

Purpose Myocardial washout of the potassium analogue 82 Rb may indicate tissue impairment. Few studies have evaluated its usefulness for viability assessment, and controversial results were reported. We revisited this topic using list-mode positron emission tomography (PET)/CT. Methods A total of 22 patients with chronic ischemic cardiomyopathy (ICM) and 11 control subjects with normal CT coronary angiogram were studied. Rest 82 Rb PET/CT studies were acquired in list mode and resampled to static, gated, and dynamic images. Using a 17-segment model, 82 Rb washout was determined by monoexponential fitting of myocardial time-activity curves. In ICM patients, 18 F-fluorodeoxyglucose (FDG) studies were obtained in the same session and segments were classified as normally perfused, mismatch, or matched defect. Results 82 Rb washout was minimal and homogeneous in control subjects. Normally perfused segments of ICM did not differ ( p = 0.33). ICM patients had a left ventricular ejection fraction (LVEF) of 25 ± 12%, 25/353 mismatched, and 46/353 matched defect segments. 82 Rb washout was higher in hypoperfused vs normal segments ( p