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99mTc-sestamibi: its clinical role as a viability agent
1CNR Institute of Clinical Physiology, Pisa, Italy.
Insights
99mTc-sestamibi uptake in myocardial segments is sensitive to blood flow reduction but less accurate than thallium-201 for assessing myocardial viability, especially in dyssynergic segments.
Area of Science:
- Nuclear cardiology
- Cardiovascular imaging
Background:
- The relationship between viable myocardium and 99mTc-sestamibi uptake requires further definition.
- Preliminary data suggest reduced uptake isn't always scar, and it correlates with coronary stenosis severity.
Purpose of the Study:
- To define the relationship between rest thallium-201 and 99mTc-sestamibi uptake in dyssynergic segments.
- To evaluate 99mTc-sestamibi as a viability agent in patients with ventricular dysfunction.
Main Methods:
- Studied 10 patients with ventricular dysfunction.
- Compared rest thallium-201 and 99mTc-sestamibi uptake in myocardial segments.
- Assessed post-revascularization regional wall motion and predictive accuracy.
Main Results:
- 99mTc-sestamibi uptake was higher in normal segments than thallium-201.
- Uptake was reduced similarly in segments with stenotic arteries, regardless of wall motion abnormalities.
- 99mTc-sestamibi had lower positive (88%) and negative (69%) predictive accuracy for viability than thallium-201 post-revascularization.
Conclusions:
- 99mTc-sestamibi is a sensitive perfusion agent for detecting resting blood flow reduction.
- It can be cautiously used as a viability agent in segments with wall motion abnormalities.
- Thallium-201 remains superior for assessing myocardial viability in these contexts.
Abstract:
The correlation between the presence of viable myocardium and 99mTc-sestamibi uptake is still to be defined. Preliminary studies indicate that: 1) reduced 99mTc-sestamibi uptake at rest is not necessarily evidence of scar tissue, and 2) its uptake is correlated to the severity of coronary stenosis. To define the relationship between rest thallium-201 and 99mTc-sestamibi uptake in dyssynergic segments, we studied 10 patients with ventricular dysfunction. 99mTc-sestamibi uptake was higher than thallium-201 uptake in normal segments but was similarly reduced in segments perfused by stenotic coronary arteries with or without wall motion abnormalities. Post-revascularization studies of regional wall motion showed that 99mTc-sestamibi had a positive and a negative predictive accuracy in identifying viable segments of 88 and 69%, respectively; these values were significantly lower than that provided by Thallium-201. 99mTc-sestamibi appears to be a primary perfusion agent with a high sensitivity to blood flow reduction at rest; it can be cautiously used as a viability agent in segments with wall motion abnormalities at rest.