What is the Implication of a nonreversible defect on SMPI?
A nonreversible defect implies that there is a lack of myocardial perfusion during the rest and stress components of the scan (i.e., there is no difference between the two scans). Nonreversible defects can often be caused by artifact, such as when part of the heart is attenuated, or blocked, by a structure between the heart and the scanner. The most common structures that cause nonreversible defects via attenuation include the diaphragm (inferior wall) and breast tissue (anterior wall and apex). When nonreversible defects are associated with an actual cardiac pathologic condition, they are related to scarring, such as from prior myocardial infarction, or chronically ischemic but viable hibernating myocardium. An infarct should have decreased perfusion during stress and rest images because it is dead tissue