PT - JOURNAL ARTICLE AU - Iida, Hidehiro AU - Tamura, Yoshikazu AU - Kitamura, Keishi AU - Bloomfield, Peter M. AU - Eberl, Stefan AU - Ono, Yukihiko TI - Histochemical Correlates of <sup>15</sup>O-Water–Perfusable Tissue Fraction in Experimental Canine Studies of Old Myocardial Infarction DP - 2000 Oct 01 TA - Journal of Nuclear Medicine PG - 1737--1745 VI - 41 IP - 10 4099 - http://jnm.snmjournals.org/content/41/10/1737.short 4100 - http://jnm.snmjournals.org/content/41/10/1737.full SO - J Nucl Med2000 Oct 01; 41 AB - A method has been proposed to quantitate the myocardial water-perfusable tissue fraction (PTF) in the area of hypoperfused 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 H215O distribution, obtained after injection of a large bolus of H215O. The defect surface area identified on PTF agreed well quantitatively with the morphometric estimates of the surface area of myocardial infarction. PTI agreed with the absolute proportion of histochemically defined normal myocardium (0.87 ± 0.09 and 0.83 ± 0.08, respectively; P &lt; 0.01). Both PTF and PTI decreased significantly in segments of myocardial infarction and showed a significant difference between the transmural and nontransmural myocardial infarction. Conclusion: The absolute mass and proportion of histochemically defined noninfarcted tissue may be quantitated with PTF and PTI in the area of myocardial infarction segments.