Clinical evaluation of 99mTc-pyrophosphate myocardial emission computed tomography: comparison with planar imaging.

To depict the three-dimensional distribution of 99mTc-pyrophosphate in the heart, emission computed tomography (ECT) was performed, following the conventional planar imaging, in 32 cases with suspected acute myocardial infarction (AMI). There were 23 cases with evidence of AMI, 7 with unstable angina (UA), and 2 with dilated cardiomyopathy (DCM). While the planar images showed discrete cardiac activity in only 11 of the 23 cases (48%) with AMI, the ECT images delineated focal myocardial uptake clearly in 20 of them (87%). On the other hand, the ECT images revealed cardiac blood-pool activity without significant myocardial uptake in all cases with UA and DCM in which the planar images showed diffuse activity. Thus, the ECT imaging of 99mTc-pyrophosphate seems to be a valuable technique for assessing the presence and localization of myocardial necrosis, especially in cases showing diffuse cardiac activity in the planar imaging.