Quantification of severity and redistribution of ischemic and infarcted myocardium by thallium-201 polar map

Quantitative analysis of the polar map obtained from Tl-201 single photon emission computed tomogram was employed to assess regional myocardial viability in 66 patients with single vessel coronary artery disease and 16 control subjects. Counts of region of interest in the stenotic and infarcted lesions and normal reference areas were calculated on the polar map. Severity of hypoperfused myocardium was determined as initial percent uptake (%Ui) and delayed percent uptake (%Ud). Redistribution was analyzed as a ratio of %Ud to %Ui (%Ud/%Ui). In the control group, the average %Ui was 85.8±9.4 and %Ud/%Ui was 1.03±0.04. Twenty five with reversible defect showed reduced %Ui (51.5±13.3) and increased %Ud/%Ui (1.37±0.26). Fourty one cases with non-reversible defect were divided into two groups according to the value of %Ui. In the first group with a high %Ui (n=17), the average %Ui was 74.5±4.7 and %Ud/%Ui was in normal range (1.06±0.06). In the second group (n=24), %Ui was most reduced (31.7±8.7), although %Ud/%Ui was in normal range (1.05±0.17). No significant correlation was shown between %Ui and %Ud/%Ui in the two groups with non-reversible defect. Correlation between %Ui and %Ud/%Ui was high (r=-0.76) in the group of reversible defect and the group of non-reversible defect with minimal reduced %Ui. It is concluded that the quantitative criteria obtained from polar map is valid to assess regional myocardial viability. The quantitative imaging data were also compared with coronary angiographic and left ventriculographic data. (author)