Single photon emission computed tomography myocardial imaging: clinical applications and future directions

Single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) has proven to be an invaluable tool in the non-invasive assessment of patients with cardiovascular diseases. Exercise and pharmacologic stress SPECT MPI has been extensively studied and validated in the diagnosis and prognosis of patients with known and suspected coronary artery disease. In addition to the assessment of perfusion, electrocardiography-gated SPECT offers additional functional and volumetric information that can have significant implications on patient care. SPECT also has well-developed applications in systolic heart failure for identifying viable myocardium and predicting response to revascularization. Emerging applications of SPECT imaging include: l) phase analysis for quantitative assessment of LV dyssynchrony that may serve to improve patient selection for CRT; 2) application of heart-to-mediastinal ratio via 123I meta-iodobenzylguanidine (I-MIBG) imaging for the prediction of sudden death in patients with reduced left ventricular function, that may serve to improve patient selection for ICD therapy, and 3) use of metabolic tracers to identify the changes of ''ischemic memory'', which may help with rapid and appropriate triage of patients in the emergency room setting. SPECT MPI remains a cornerstone of clinical care that is evolving with emerging and novel applications that will continue to improve the care of patients with cardiovascular disease in the future.