Thallium-201 imaging with color display computer system in old myocardial infarction.

In 13 patients with old myocardial infarction diagnosed with use of the electrocardiogram, coronary angiogram and left ventriculogram and in 11 patients without infarction, thallium-201 imaging with a color display computer system was carried out. In the group without infarction the average ratio of activities in two regions of interest within the myocardial wall, excluding the apex, was 1.14 (1.08 to 1.23). In the group with infarction the average ratio of noninfarcted to infarcted areas was 1.44 (1.23 to 1.78). Objective detection of infarction was possible in 12 patients (92 percent) in the group with infarction. In two patients, the earlier electrocardiographic pattern of infarction had resolved by the time of imaging. These results suggest that the sensitivity of thallium-201 imaging in the diagnosis of old myocardial infarction may be greatly enhanced by objective and quantitative analysis using a color display computer system.