Histochemical Correlates of 15O-Water–Perfusable Tissue Fraction in Experimental Canine Studies

A method has been proposed to quantitate the myocardial water-perfusable tissue fraction (PTF) in the area of hypoper-fused asynergic segments using 15O-water (H215O) and PET. This study investigated the histochemical correlates of PTF (and perfusable tissue index, PTI) in a canine model of old myocardial infarction. Methods: Myocardial infarction was produced in 12 mongrel dogs, and PET was performed 1 mo later, providing quantitative parametric images of PTF, regional myocardial blood flow (MBF), and extravascular density from H215O, 15O-carbon monoxide, and transmission datasets. At the end of scanning, the myocardium was sectioned, and the PET images were compared directly with the corresponding myocardial sections. Results: The distribution of tissue necrosis identified by histochemical staining corresponded well with the defect in PTF but not in MBF. PTF agreed with the equilibrium images of myocardial H215