1986 Volume 53 Issue 4 Pages 345-355
Clarification of the clinical usefulness of Single Photon Emission Computed Tomography (SPECT) compared to conventional planar Thallium-201 chloride myocardial scintigraphy in terms of its relationship to other clinical examinations was investigated.
Patients consisted of 27 acute myocardial infarctions, 25 male and 2 female. Their average age was 61.2. For 25 patients it was their first attack of acute myocardial infarction, and 2 had suffered previous myocardial infarction.
Myocardial scintigraphy was taken within three weeks after the onset. The left ventricle was divided into 6 anatomical segments in both myocardial images and each segment had a score from 1 to 5 points ; 5 : severe defect, 4 : medium defect, 3 : low defect, 2 : lowered activity sus-pected, 1: normal activity. Other clinical examinations were an electrocardiogram, a coronary angiogram, a left ventriculogram, and a cardiac pool scintigram. Then the score and other clinical information were compared.
The following results were obtained:
1) In the apex, the scores were remarkably higher with SPECT than those with the planar image. However, in the anterior portion or septum, the scores were almost the same. In the inferior, lateral or posterior portions the scores were slightly higher on SPECT than those with the planar image.
2) Eleven out of 27 cases showed a high correspondence between the planar image and SPECT, but the other 16 were different in the identification of infarct sites. In 11 out of 16, SPECT was more accurate, but in another 3 out of 16, the planar image was more accurate because of overdiagnosis by SPECT.
3) The defects of apex might be overdiagnosed by SPECT.
4) SPECT scores showed a good correlation with the severity of wall motion disturbance.
5) Patients with severe broad defects on anteroseptal or anteroseptolateral identified by SPE-CT showed significantly lower ejection fraction than others.
6) The total SPECT score was inversely well correlated with ejection fraction. (r=-0.6948, p<0.01)
From these results, it can be concluded that SPECT is a reliable tool for estimating the localization and extent of acute myocardial infarction. Moreover, the grading score of SPECT is useful for estimating a cardiac function in the acute phase of myocardial infarction.
