Washout curves from myocardial infarctions in dogs, studied by contrast-enhanced computed tomography.

Experimental myocardial infarctions appear on CT scans as areas of mixed high and low densities. As the healing of the infarction proceeds, the low-density areas gradually decrease in size and disappear completely within 5 weeks. Healed infarctions appear as a high-density area only. In order to explore the contrast medium transport in the infarcted area, washout curves were constructed from the infarct components, the normal myocardium, and the left ventricular cavity at regular intervals over a period of 145 days. All regions except the low-density zones showed continuous decrease in density during the washout. The low-density zones showed gain in density during the first 10 to 15 min of washout, probably representing slow diffusion of contrast medium into the necrotic tissue. During the first 5 weeks of the healing process, the washout curve from the low-density zones gradually became similar and ultimately conformed to the other curves, concomitant with the ongoing neovascularization of the lesion.