Spect Cardíaco

CUpdating SPECT topics: Cardiac SPECT

Updating SPECT Topics: Cardiac SPECT
Margarita Núñez. Escuela Universitaria de Tecnología Médica, Centro de Medicina Nuclear, Hospital de Clínicas. Av. Italia s/n Montevideo 11200 - Uruguay. Tel: (598 2) 487 1407 Fax: (598 2) 487 0230 Email: margan@hc.edu.uy

Margarita A. Núñez, CNMT. Escuela Universitaria de Tecnología Médica. Montevideo, Uruguay.Updating SPECT topics: Cardiac SPECT

CARDIAC SPECT
1. CLINICAL INDICATIONS Nuclear cardiology is a widely available, cost-effective, non-invasive methodology in use for more than two decades with which a large amount of experience has been accumulated. The technique is in constant development and its application has been growing to constitute nowadays about 30-40% of all nuclear medicineprocedures in an average institution. Most indications are related to coronary artery disease (CAD) evaluation and are supported by large amounts of scientific evidence. The following are some of such indications: a) Diagnosis of CAD. This application was probably the first to demonstrate the efficacy of nuclear cardiology studies, specially the investigation of myocardial perfusion together withstress testing. According to Bayes’ theorem, patients with intermediate pre-test probability of CAD benefit most from the study (i.e., patients with chest pain and negative exercise test, asymptomatic patients with ECG changes or patients with non-diagnostic ECG). b) Prognosis and risk stratification in chronic CAD patients. This is an application of increasing frequency regarding decision-making andrational patient management. Considering the findings of a myocardial perfusion study in terms of number, extension and severity of ischemic defects, the patient can be assigned a low, intermediate or high probability for future cardiac events and the most appropriate therapeutic choice can be selected. This is also useful for non-cardiac preoperative evaluation. c) Unstable angina. Most patientsadmitted with diagnosis of unstable angina are usually derived for immediate invasive evaluation. However, it has been demonstrated that if stabilization is achieved, these patients can be safely submitted for stress myocardial perfusion studies to determine the extent and severity of induced ischemia in order to choose between invasive and non-invasive strategies. d) Myocardial infarction. Thereis strong evidence that patients with the so-called “non-Q wave” myocardial infarction can benefit from non-invasive treatment unless a functional study result indicates high ischemic risk. In patients with transmural, non-complicated myocardial infarction, a non-invasive functional evaluation at discharge is suggested for risk-stratification, which can be done through a stress perfusion studypreferably with gated SPECT, in order to determine the need for cardiac catheterization. e) Evaluation of revascularization procedures. Percutaneous transluminal coronary angioplasty (PTCA) is a minimal-invasive revascularization technique but has a relatively high rate of restenosis, even with stent implantation. In patients with chest pain and/or positive/indeterminate stress tests post-PTCA,myocardial perfusion studies can determine the presence of restenosis or detect a new affected vascular territory, or even rule out significant ischemia. In patients with previous by-pass surgery, perfusion studies are also useful for assessment of graft patency. f) Chest pain evaluation in the emergency department. Margarita A. Núñez, CNMT. Escuela Universitaria de Tecnología Médica. Montevideo,Uruguay.
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Updating SPECT topics: Cardiac SPECT Chest pain is one of the most frequent cause of emergency admissions worldwide. Many patients are really undergoing a cardiac ischemic episode, but many more have non-cardiac causes of pain that would need no hospitalization. Chest pain units have been installed in some institutions to rationally evaluate these patients, and acute rest myocardial...