Quantification of myocardial infarct size by thallium-201 myocardial scintigraphy

We developed a method for quantitative assessment of infarct size by thallium (Tl)-201 myocardial scintigraphy. Infarct size assessed by the method was compared with total CK released from myocardium after infarction (ΣCK) in 43 patients with myocardial infarction. Tomograms were quantified by automatically generating maximum-count circumferential profiles, which were compared with normal limit profiles derived from 60 normal controles. The ''defect volum'' was defined as the percentage of circumferential points falling below normal. The ''defect severity index'' was also defined as the defect volume weited for the relative reduction in count within the defect zone. In all patients both defect volume and defect severity index has no significant relation with ΣCK. However, in antero-septal infarction and in inferior infarction there was a good relation between them. The coefficient of corelation between defect severity index and ΣCK was higher than that between defect volume and ΣCK. In conclusion defect severity index was useful for quantified infarct size in antero-septal and inferior infarction. (author)