Cardiac tomography

Recently, the demands placed on 201Tl cardiac imaging have become more complex. It is no longer sufficient to merely identify a myocardial scar or to diagnose myocardial ischemia by observing a defect at stress that fills in at equilibrium. Now there is a greater need to identify exactly the ischemic site, to determine how much peri-infarctional ischemic tissue remains, and to address how a specific site has responded after intervention of surgery or angioplasty. This information is difficult to obtain from a planar scan but is considered easier to acquire with transaxial cardiac tomography. Fortunately, these demands have occurred at a time when most of the previous problems with cardiac tomography had been resolved. The computer has become an integral part of the nuclear cardiology so that the only additional cost for tomography would be a rotating gantry. However, successful transaxial measurements are not easily achieved. With the limited dose of 21Tl there would be a minimum of counts available cost for tomography would be a rotation gantry. However, successful transaxial measurements are not easily achieved. With the limited dose of 201Tl there would be a minimum of counts available for tomographic reconstruction so that methods of acquisition, reconstruction, filtering, and display must all be optimized. This chapter discusses some of these technical factors and shows how they relate to clinical results