Potential and limitations of Tc-99m sestamibi scintigraphy for the diagnosis of myocardial viability
Cornel, J.H.; Arnese, M.; Forster, T.; Postma-Tjoa, J.; Reijs, A.E.; Fioretti, P.M.
Herz 19(1): 19-27
1994
ISSN/ISBN: 0340-9937 PMID: 8150411 Document Number: 428640
Sestamibi is a Tc labeled radiotracer particularly suitable for myocardial perfusion studies, providing similar information as thallium scintigraphy for the diagnosis of coronary artery disease. In comparison with thallium, sestamibi has the advantage of improved imaging properties due to its higher gamma emission. This is particularly relevant when SPECT imaging is considered. The myocardial uptake of sestamibi is partially passively, related to the myocardial flow, and is also related to the metabolic cellular activity, as it is proportional to the electrochemical gradient generated at cell membrane level. While the role for sestamibi in diagnosing coronary artery disease is well accepted, it is still controversial for the assessment of myocardial viability. Clinical studies reported by others and results from our own institution will be described both in the setting of a recent myocardial infarction (myocardial stunning) and of long-standing left ventricular dysfunction (hibernating myocardium). The results concordantly suggest that sestamibi underestimates myocardial viability, compared to the Accepted standards of thallium (rest-redistribution or stress-reinjection protocols), 18-F FDG PET and also in the prediction of left ventricular functional recovery after revascularization. However, the data available at present arye very limited, particularly after revascularization. Furthermore, according to new promising results, the role of sestamibi in the setting of myocardial viability has potential for improvement, if the injection at rest will be performed during nitrates. It is also foreseen that the combined use of sestamibi perfusion/wall motion scan (first pass and/or gated perfusion studies) and the development of new softwares for attenuation correction might improve the results in the setting of myocardial viability.