The new method of evaluation for the regional myocardial function using the regional wall thickening curve obtained by ECG-gated 201Tl planar myocardial scintigraphy

A new method was developed for obtaining an increase rate of regional myocardial systolic wall thickness (%WT) in ECG-gated Tl-201 myocardial scintigraphy. Its value was assessed in the clinical setting in comparison with %WT obtained by echocardiography. The subjects were a total of 18 patients with cardiac diseases, including angina pectoris (7), hypertension (3), dilated cardiomyopathy (4), aortic valve stenosis (2), aortic valve regurgitation (one) and sick sinus syndrome (one). Left ventricular septal and posterolateral segments were defined as regions of interest (ROI) on LAO 45deg planar images to correspond to the sites on echocardiographic left ventricular short axial M mode images. In addition, rectangular ROI, which directly crossed the ventricular wall, was assigned to determine changes in myocardial wall thickness, whereby time-activity curve (TAC) was prepared. TAC obtained so far was analogous to that obtained by ultrasound crystal method in an animal experiment. Thus the TAC was supposed to reflect changes in regional myocardial wall thickness. Furthermore, enddiastolic count (EDC) and endsystolic count (ESC) were obtained. %WT was obtained by a formula of (ESC - EDC)/EDC*100. %WT obtained in this way correlated positively with that obtained by echocardiography, for both septal segment (r=0.78) and posterolateral segment (r=0.77). These findings suggested that the regional wall thickening curve can be used in the clinical setting. (N.K.)