Assessment Of Myocardial Ischemia/Viability In Patients With Myocardial Infarction Using Single Photon Emission Computed Tomography (SPECT) Technique

Objective: Although the 3~4 hour (h) thallium-201(201Tl) redistribution imaging and the 201Tl re-injection imaging have been widely used for evaluation of myocardial ischemia/viability after myocardial infarction, they underestimated a considerable proportion of ischemic/viable myocardium to a different degree. Previous studies abroad have showed that 201Tl late imaging may enhance the detection of myocardial ischemia/viability, but remains controversial. In addition, it has seen no systematic reports about its clinical values for estimation of myocardial ischemia/viability at home and abroad. The purpose of the present study was to evaluate the potential advantage of the 24h versus the 3h imaging after the resting injection of 201Tl in estimating viable myocardium in patients with myocardial infarction.Methods: Thirty-eighty patients with myocardial infarction underwent the initial, the 3h, and the 24h imaging after intravenous injection of 4~5mCi 201Tl. Image quality analysis was performed using a four-grade model: excellent, good, fair and poor. The initial and the 3h images, the initial and the 24h images, and the 3h and the 24h images were analyzed double-blindedly so as to compare the detection capabilities for ischemic/viable myocardium between the 24h late imaging and the 3h redistribution imaging. Thirty-two patients underwent coronary angiography and successful revascularization of stenotic coronary arteries. The relationship between the severity of coronary artery stenosis and the time to completed redistribution of myocardial perfusion defects following resting injection of 201Tl was investigated. The sensitivity, specificity and accuracy for predicting an improvement in function post revascularization were compared between the 24h late imaging and the 3h redistribution imaging by way of a follow-up echocardiography.