Assessment of myocardial perfusion by positron emission tomography

Positron emission tomography (PET) represents an advanced imaging technology for the noninvasive evaluation of regional myocardial blood flow. Several blood flow tracers are available, including cyclotron-produced radiopharmaceuticals such as [¹⁵O]H₂O and [¹³N]NH₃ and generator-produced rubidium-82 ([⁸²Rb]-) and copper-62 ([⁶²Cu]-) pyruvaldehyde-bis-(N-4-methylthiosemicarbazone) (PTSM). ⁸²Rb and [¹³N]NH₃ are the most commonly employed tracers for the qualitative evaluation of regional myocardial perfusion. Their use allows the accurate detection of coronary artery disease in combination with pharmacologic stress. Initial comparative studies with thallium-201 (²⁰¹Tl) single-photon emission computed tomography (SPECT) have shown that PET has a higher diagnostic accuracy. Beyond improved diagnostic performance, the quantitative flow measurements provided by PET represent an important advance in nuclear cardiology. The radiopharmaceuticals [¹⁵O]H₂O and [¹³N]NH₃ have been applied for the noninvasive determination of regional coronary reserve. Quantification of blood flow based on tracer kinetic modeling yields blood flow values in close agreement with determinations provided by invasive procedures. The noninvasive quantification of blood flow provides a useful research and clinical tool for the objective assessment of therapeutic interventions as well as pathophysiologic alterations of regional myocardial blood flow in various cardiac diseases.