Uses nuclear isotopes to assess LV perfusion and contractile function.
Ventricular Function Assessment 
Contractile function can be assessed during gated single-photon emission computed tomography (SPECT) myocardial perfusion exercise test imaging (see below). Occasionally, blood pool imaging is obtained by injecting IV 99m Tc-labeled albumin or RBCs to quantify LV ejection fraction.
Nuclear Myocardial Perfusion Assessment
SPECT imaging, most commonly using 99m Tc-labeled compounds (sestamibi or tetrofosmin), or PET imaging (82Rb or 13NH3), obtained at peak stress and at rest, depicts zones of prior infarction as fixed defects and regions of inducible myocardial ischemia as reversible defects. Nuclear imaging is more sensitive, but less specific, than stress echocardiography for detection of ischemia.
For pts who cannot exercise, pharmacologic perfusion imaging with adenosine, regadenoson, dipyridamole, or dobutamine is used instead (Chap. 121. Chronic Stable Angina). For pts with LBBB, perfusion imaging with adenosine or dipyridamole is preferred to avoid artifactual septal defects that are common with exercise imaging.
Pharmacologic PET scanning is especially useful in imaging obese pts and to assess myocardial viability. Thallium-201 SPECT imaging can also be utilized to assess viability.
Outline