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Enhanced thallium-201 uptake after reinjection: relation to regional ventricular function, myocardial perfusion and
Insights
Enhanced thallium-201 uptake after reinjection in myocardial segments with irreversible defects indicates viable myocardium. This finding is associated with better wall motion and coronary collateralization in patients with coronary artery disease.
Area of Science:
- Cardiology
- Nuclear Medicine
- Diagnostic Imaging
Background:
- Coronary artery disease (CAD) often leads to left ventricular (LV) dysfunction.
- Assessing myocardial viability is crucial for guiding treatment decisions in patients with CAD.
- Thallium-201 (201Tl) scintigraphy with reinjection is used to evaluate myocardial perfusion and viability.
Purpose of the Study:
- To clarify the significance of enhanced 201Tl uptake after reinjection in segments with irreversible defects on initial imaging.
- To correlate reinjection findings with myocardial viability, wall motion, and coronary anatomy.
Main Methods:
- Exercise-redistribution (ER) 201Tl scintigraphy with reinjection was performed in 34 patients with CAD and LV dysfunction.
- Resting technetium-99m methoxy isobutyl isonitrile (MIBI) imaging, 2D-echocardiography, and coronary angiography were also conducted.
- Myocardial segments were quantitatively analyzed for 201Tl uptake, wall motion, and MIBI uptake.
Main Results:
- Of irreversible defects (ID) on ER 201Tl images, 44% showed enhanced uptake after reinjection (Re+).
- Re+ segments had significantly less severe wall motion abnormalities and higher MIBI uptake compared to segments with no reinjection enhancement (Re-).
- The severity of coronary artery stenosis was similar between Re+ and Re- segments, but collaterals were more frequent in Re+.
Conclusions:
- Enhanced 201Tl uptake after reinjection in segments with ID on ER images signifies viable myocardium in patients with CAD and LV dysfunction.
- This viability is associated with preserved or less impaired wall motion, higher MIBI uptake, and the presence of coronary collaterals.
Abstract:
The aim of this study was to clarify the significance of enhanced thallium-201 (201Tl) uptake after reinjection following 4-hour redistribution imaging. Thirty-four patients with coronary artery disease (CAD) and left ventricular (LV) dysfunction (ejection fraction 32 +/- 10%) underwent exercise-redistribution (ER) 201Tl scintigraphy with rest injection, resting technetium-99m methoxy isobutyl isonitrile (MIBI) imaging, 2D-echocardiography, and coronary angiography. Wall motion (WM) was graded on echocardiographic images. A total of 510 myocardial segments were quantitatively analyzed. A total of 267 (52%) segments had normal (N) 201Tl uptake, 53 (10%) reversible (RD), and 190 (37%) irreversible (ID) 201Tl defects on ER images. Of these 190 ID, 84 (44%) showed enhanced 201Tl uptake after reinjection (Re+) and 106 (56%) remained unchanged after reinjection (Re-). MIBI uptake was significantly higher in RD compared to Re+ and Re- (both p < 0.01), and in Re+ compared to Re- (p < 0.01). The WM score was significantly lower in RD and Re+ compared to Re- (p < 0.01), while no difference was observed between RD and Re+. The severity of coronary artery stenosis was significantly lower in RD compared to Re+ and Re- (both p < 0.01), but no difference was observed between Re+ and Re-. The occurrence of collaterals was significantly higher (p < 0.01) in Re+ (69%) compared to Re- (38%). In conclusion, in patients with CAD and impaired LV function, enhanced 201Tl uptake after reinjection in myocardial segments with ID on ER images was associated with less severe WM abnormalities, higher MIBI uptake and the presence of collaterals.(ABSTRACT TRUNCATED AT 250 WORDS)