Myocardial perfusion scintigraphy (MPS) is a well established clinical imaging technique for the diagnostic and prognostic workup of coronary artery disease, and it has been the mainstay of cardiovascular radionuclide applications for decades. The field of cardiovascular imaging, however, is changing. Several alternative imaging methodologies for non-invasive assessment of perfusion have emerged. At the same time, nuclear imaging technology has progressed significantly towards higher sensitivity and resolution, and novel, highly specific radiotracers have been introduced. These developments are indicators of a steady evolution of nuclear cardiology beyond the assessment of myocardial perfusion, towards characterisation of molecular events on the tissue level. As such, radiotracer techniques will take a leading role in the emerging paradigm of personalised medicine, where preventive/therapeutic strategies are based on individual disease biology.

MYOCARDIAL PERFUSION SCINTIGRAPHY: THE CLINICAL MAINSTAY

Since its introduction around 35 years ago,^w1 MPS has evolved into a robust, well established clinical tool to assess myocardial perfusion for diagnosis and prognosis in patients with known or suspected ischaemic heart disease.

Myocardial perfusion SPECT

Tl-201 was the first myocardial perfusion radiotracer, which became commercially available in 1977.^w2 In the early 1980s, Tc-99m labelled perfusion tracers (Tc-99m-sestamibi and -tetrofosmin) were introduced to overcome some limitations of Tl-201.^w3–5 The higher energy of emitted gamma rays (140 keV vs 69–83 keV) reduces attenuation and scatter artefacts, resulting in better image quality. The shorter radioactive half-life (6 h vs 72 h) allows for administration of higher tracer doses with less radiation exposure. Of note, the molecular characteristics determining myocardial uptake and retention of these tracers (Na/K-ATPase for Tl-201, mitochondrial binding for sestamibi and tetrofosmin)—which are proportional to myocardial blood flow within most parts of the physiologic flow range, but underestimate true flow in the higher flow range—are well understood.^{w6 w7}

The diagnostic performance of MPS has been assessed extensively. A recent study of 2560 …