Human pathologic correlation with PET in ischemic and nonischemic cardiomyopathy

To assess the correlation between myocardial perfusion, metabolism and histologic findings in patients with cardiomyopathy, we evaluated myocardial perfusion and metabolism using positron emission tomography (PET) with ¹³NH₃ (ammonia) and ¹⁸FDG (fluoro-2-deoxy-glucose) in nine patients prior to undergoing orthotopic cardiac transplantation. Four patients had ischemic cardiomyopathy (ISCM) and five had nonischemic cardiomyopathy (NISCM). Normalized circumferential profile analyses of representative mid- ventricular perfusion and metabolism PET images were performed for each patient. A corresponding mid-ventricular transaxial slice was obtained from the formalin fixed explanted heart and processed for routine histology. Hematoxylin-eosin stained and Masson trichrome stained sections were evaluated and the percentage of the slice occupied by infarct was determined planimetrically at 10-degree intervals in a circumferential manner. A significant correlation was found between circumferential normalized PET count density profile of perfusion and metabolism in both the ischemic and nonischemic groups (ISCM range r = 0.65-0.75; NISCM range, r = 0.70-0.87). Furthermore, there was a correlation in the ISCM group between the extent of matched perfusion/metabolism defects and transmural infarct involvement (r = 0.66-0.88). PET perfusion and metabolic data closely correlate with pathologic infarction in human hearts of ischemic cardiomyopathy patients.