Myocardial perfusion imaging using single-photon emission computed tomography.

Myocardial perfusion single-photon emission computed tomography (SPECT) provides three-dimensional physiological information to assess myocardial blood flow at stress and rest and myocardial viability. The availability of perfusion agents with different uptake mechanisms, thallium 201, technetium 99m-sestamibi, and 99mTc-teboroxime, has created considerable flexibility in how these agents are imaged and interpreted. The higher photon flux and fixed distribution of 99mTc sestamibi allows for multiple-gated acquisition, which yields the potential for the assessment of myocardial thickening. Pharmacological agents, such as dipyridamole, adenosine, and dobutamine, may be used with myocardial perfusion SPECT as an alternate stress procedure in patients who cannot exercise adequately. SPECT reconstruction is limited by the current lack of clinically implemented algorithms to compensate for photon scatter and attenuation or for finite spatial resolution. Data-based quantification procedures that compare a patient's results to a database of normal patients assist the diagnosticians in circumventing these limitations.