Figure 18. 53 year old male with a previous history of an inferior MI being considered for revascularization. Both a ventriculogram and an equilibrium radionuclide angiocardiogram showed widespread wall motion abnormalities and global decrease in systolic function (ejection fraction = 28%). The study was performed as a dipyridamole 201Tl stress study with additional images at four hours and following reinjection. Only the stress and reinjection images are shown. There is severe (<50% of peak) fixed reduction of activity in the inferior wall (short arrow), a reversible septal abnormality (long arrow) and a partially reversible anterior wall abnormality (arrowhead). In summary, the examination demonstrates extensive ischemia and, with the exception of the inferior wall, viability of all segments.

probability (Fig. 19). As can be seen the greatest changes in probability occur when applying this test to patients who have an intermediate pre-test probability of disease.

Sequential Bayesian analysis refers to the situation where the post-test probability after a diagnostic test becomes the pre-test probability for the next test. Suppose that on the basis of risk factors a patient is assigned a pre-test probability of 20%. He then undergoes a GXT after which the (post-test) probability is raised to 60%. This 60% probability now becomes the pre-test probability for any subsequent examination such as a myocardial perfusion study.

Why is it necessary to have polar maps based on a normal database? Shouldn't perfusion to all portions of the heart be

Table 5. Derivation of post-test probability of coronary artery disease (CAD) with positive and negative test results from myocardial perfusion imaging (MPI).

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