Adjunctive imaging is part of the ischemic heart disease tests that are carried out to assess risk or progress of ischemic heart disease. The sensitivity and specificity of other methods of assessment is augmented with the addition of noninvasive modalities to image myocardial perfusion or wall motion (by echocardiography). These tests are employed if the patient's resting electrocardiogram has ST segment changes, which would interfere with diagnostic interpretation. They are also utilized in those with nondiagnostic or equivocal treadmill stress tests and in patients who are unable to exercise.
Scintigraphic imaging attempts to image myocardial perfusion, and involves infusing a radioactive isotope intravenously and scanning the heart with a tomographic collimeter (SPECT Camera) to detect radioactive emission. Images acquired at peak exercise are compared with those acquired at rest. A regional reduction in perfusion at peak exercise which normalizes on the rest scan (reversibility) signifies ischemia. Fixed defects revealing no reversibility between stress and rest imaging are generally indicative of regional scarring from a myocardial infarction.