[Quantitative correlation between thallium-201 myocardial emission computed tomography and left ventriculography in...

We evaluated a clinical usefulness of quantitative analysis of myocardial emission computed tomographic (ECT) images in 28 patients with old myocardial infarction and 10 healthy volunteers. Circumferential profile analysis was performed in five or six short-axial images of the left ventricle reconstructed from ECT. Mean regional anterior, inferoposterior, lateral and septal percent thallium uptakes were calculated from three short-axial (basal, central and apical) images. The percent infarct size was evaluated as a percentage of the thallium perfusion defect volume to the total left ventricular myocardial volume. Left ventricular hemiaxis shortening was calculated at three ventricular levels corresponding to the three short-axial ECT images. Mean value of all hemiaxis shortening in RAO and LAO projections (total hemiaxis shortening) and left ventricular ejection fraction (EF) were obtained. There was a significant correlation between mean percent thallium uptake and percent hemiaxis shortening in the left ventricular anterior and inferoposterior segments. On the contrary, no statistically significant correlation was shown between these two parameters in the left ventricular lateral and septal segments. Percent infarct size obtained with ECT significantly correlated with total hemiaxis shortening and EF (r = -0.63 and -0.60, respectively). It was concluded that there is a close relationship between the size of infarcted myocardium evaluated by ECT and either of the regional or global left ventricular dysfunction assessed by LVG.