A welcomed new myocardial perfusion imaging agent for positron emission tomography.

It has been quite some time since a new myocardial perfusion agent for radionuclide imaging was introduced into clinical practice. For more than 30 years, rest and stress myocardial perfusion imaging (MPI), employing first planar and then single photon emission computed tomography (SPECT) technology, have been performed with thallium201, Tc-99m sestamibi and Tc-99m tetrofosmin. MPI with these agents has provided useful diagnostic and prognostic information superior to that attained with exercise electrocardiography alone in patients with suspected or known coronary artery disease (CAD).1 With the exception of diabetic patients1 and patients with advanced chronic kidney disease,2 subjects with normal exercise perfusion scans have a 1.0% death or nonfatal infarction rate per year, whereas patients with abnormal scans have an 6% yearly hard event rate.1 Patients with normal pharmacological stress scans have a slightly higher annual event rate3 because patients who are unable to exercise are at higher clinical risk for CAD. For positron emission tomography (PET) imaging, the dominant perfusion tracers used in the clinical setting are N-13 ammonia and Rb-82, the latter eluted from a generator.4 The short-lived cyclotron-produced radionuclide Oxygen-15 water is another PET perfusion agent that has predominantly been used in the research setting. Sensitivity and specificity of PET myocardial perfusion imaging appear to be higher compared with that reported for SPECT,5 and the prognostic value of PET MPI is similar to that observed with SPECT.6,7 One potential advantage of PET over SPECT MPI is the ability to quantitate myocardial blood flow in mL · min 1 · g 1 and measure coronary flow reserve using dynamic imaging and tracer kinetic models.8,9