THE INCIDENCE OF SCINTIGRAPHICALLY VIABLE AND NONVIABLE TISSUE BY RB-82 AND FLUORINE-18-FLUORODEOXYGLUCOSE POSITRON EMISSION TOMOGRAPHIC IMAGING IN PATIENTS WITH PRIOR INFARCTION AND LEFT-VENTRICULAR DYSFUNCTION

Background. Although reversible perfusion defects, perfusion-metabolis m mismatch and match patterns are important for differentiating viable from nonviable myocardium, the frequency of these scintigraphic patte rns has not been reported. The study objective was to establish the in cidence of these scintigraphic patterns to estimate the clinical need for metabolic positron emission tomography for evaluating tissue viabi lity in patients with prior myocardial infarction (MI). Methods and Re sults. Rb-82 perfusion images were interpreted to identify reversible or irreversible defects, followed by determination of their F-18-fluor odeoxyglucose (F-18-FDG) uptake pattern. In 155 patients with prior MI , analysis of 613 abnormal segments showed reversible perfusion defect s in 13%. The 87% irreversible defects, 18% showed perfusion-metabolis m mismatch, whereas 69% showed the match pattern. Reversible perfusion defects and perfusion-metabolism mismatches were noted in 20% (31/155 ) and 29% (45/155) of patients, respectively, whereas the match patter n was noted in 51% (79/155) of patients. Conclusion. Irreversible perf usion defects were common in our patients with prior MI, and distincti on between viable and nonviable tissue was not possible by perfusion i maging alone. The identification of hibernating myocardium was possibl e only with the additional F-18-FDG imaging in about one third of pati ents. This indicates a significant clinical demand for F-18-FDG imagin g that identifies patients who will benefit from revascularization.