Estimation of infarct size by three-dimensional surface display method of myocardial single photon emission CT with 201Tl

To estimate infarct size, we devised three-dimensional (3D) surface display method of 201Tl myocardial single photon emission CT (SPECT). The method was performed with maximum-count circumferential profiles (CPs) of short axis views of 201Tl myocardial SPECT. The counts of maximum-count CP were put into a pixel line with the calculated left ventricular circumferential length on each short axis slice. A 3D-surface display map was created by arrangement of these pixel lines from apex to base of left ventricle in order. The sizes of defects in myocardial phantom were calculated by this method. There was a high correlation between the real defect sizes and the calculated defect sizes. In 6 patients with anterior myocardial infarction, the infarct sizes were calculated by this method. The extent of abnormality was identified by automatic computer comparison of each patient's profiles with corresponding lower limits of normal profiles. The infarct sizes calculated by 3D-surface display method were closely correlated not only with the infarct sizes calculated by summation of defect sizes in short axis views, but also with left ventricular ejection fractions. We concluded that the 3D-surface display method of 201Tl myocardial SPECT is effective for noninvasive assessment of the extent of myocardial infarction. (author)