How is a multiple gated acquisition (MUGA) scan performed? A MUGA scan involves the radioactive tagging of the patient’s red blood cells (RBCs) so that the blood pool remains radioactive throughout the study. Radiolabeling can be performed either in vitro or in vivo. In vitro labeling requires blood to be drawn from the patient first; …
What is the difference between hibernating and stunned myocardium? Stunned myocardium refers to viable myocardium with relatively preserved perfusion on SPECT or PET imaging, normal or decreased glucose metabolism on FDG PET imaging, and decreased wall motion on echocardiography. Stunning occurs in an acute ischemic event, but by the time the patient undergoes management and …
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How is a 201 Tl resting redistribution scan performed, and how are the results of a resting redistribution scan used clinically? In a resting-redistribution scan, the patient receives an injection of 201 Tl at rest and undergoes scanning approximately 15 minutes later. The patient is scanned again approximately 4 hours later and sometimes 24 hours after injection. …
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How might a left bundle branch block on ECG affect SMPI findings? An LBBB seen on ECG can cause reversible perfusion defects in the septum during an exercise stress test. The cause has not been completely elucidated but may be related to altered depolarization of the septum from the conduction abnormality or related to left …
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Why is transient left ventricular cavity dilation on SMPI a poor prognostic sign? Transient left ventricular cavity dilation refers to the cavity appearing larger on stress images than on resting images. This is in contrast to fixed cavity dilation, which may be associated with cardiomyopathy that could be related to a number of causes including …
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What is the implication of a reversible defect on SMPI? A reversible defect implies a lack of myocardial perfusion during the stress component but normal myocardial perfusion during rest. Reversible defects can be caused by attenuation artifact but must always be assumed to be related to CAD, in which the stenotic artery cannot accommodate the …
How do SMPI studies compare with routine stress ECG studies in the evaluation of patients with CAD? Generally, a routine stress ECG is sensitive, with positive ECG stress test results indicating a high likelihood for CAD. The accuracy is significantly reduced, however, in patients with abnormal baseline ECGs or a previous history of CAD, or …