In a series of 62 male patients undergoing exercise TI-201 SPECT myocardial scintigraphy, planar 45 degrees LAO images were acquired before (2-5 minutes postinjection, P1) and after (35 minutes postinjection, P2) the initial SPECT study in order to identify those patients with redistribution during the first 30 minutes after exercise. Consensus interpretation by four readers identified early redistribution (between P1 and P2) in 11 patients (18%), rated major (change of greater than 1.5 scoring unit) in five and minor (change of 1-1.5 scoring unit) in six. Only one patient (2%) showed major early redistribution that could not be appreciated on corresponding SPECT images. In this preliminary investigation, early thallium redistribution sufficient to affect identification of significant exercise-induced ischemia on SPECT imaging was infrequent and of limited clinical importance.
