Myocardial infarct quantification in the dog by single photon emission computed tomography

Radionuclide techniques for sizing acute myocardial infarction have been hampered by the intrinsic limitations of the scintillation camera. Emission computed tomography can overcome these limitations. Single photon emission computed tomograms of the distribution of technetium-99m pyrophosphate in acute anterior and posterior infarcts were obtained in 16 dogs after death. Tomograms were also obtained in 10 dogs during life without gating. The size of the infarcts was determined by staining gross sections of the heart with nitro blue tetrazolium, dissecting out the infarcted tissue and weighing it. Infarct sizes were determined from the tomographic images and compared with the measured infarct sizes. Good images showing the location and three-dimensional extent of the infarcts were obtained in all dogs. The measured and calculated infarct sizes correlated well (r = 0.85). Comparison of the calculated sizes in the living (non-gated) and dead ("physiologically" gated) animals showed reasonable agreement (r = 0.87). Single photon emission computed tomography is a feasible and useful technique for localizing and sizing acute myocardial infarctions.