Scintigraphy and positron emission tomography

Nuclear cardiology provides important non-invasive tools in cardiac diagnostics. The present overview elucidates the impact of nuclear cardiology in the evaluation of patients with coronary artery disease (CAD). In addition to a short description of conventional scintigraphic techniques such as radionuclide angiography, SPECT myocardial scintigraphy and positron-emission tomography (PET) for each technique utility and accuracy for diagnosis, risk assessment and prognosis is considered. Sensitivity and specificity of SPECT myocardial scintigraphy for diagnosis of CAD has been reported to be 80-85% and 75-80%, respectively. Using SPECT for risk stratification it is worth mentioning that negative stress scan results in a patient with coronary artery disease may still be prognostically important because it predicts a low risk for future cardiac events. With the development of the PET-technology accuracy for diagnosis and prognosis has improved. Furthermore PET provides an elegant tool to assess metabolic processes in myocardial cells. This makes it possible to distinguish viable myocardium from non viable left ventricular segments after myocardial infarction. Accurate assessment of the extent of dysfunctional but viable myocardium (hibernating myocardium) is critically important in patients with large myocardial infarction and left ventricular dysfunction. By combining the information from PET images and the coronary angiogram an individualized plan for revascularization can be developed. PET metabolic imaging is considered the gold standard for the assessment of myocardial viability with a positive and negative predictive value of 80-85%.