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Comparison of persistent thallium perfusion defects by quantitative washout analysis with thallium reinjection in
M J Garcia1, D Neumann, R T Go
1Cardiovascular Imaging Center, Cleveland Clinic Foundation, Ohio 44195.
Insights
Quantitative analysis of thallium-201 washout predicts outcomes of thallium reinjection in patients with coronary artery disease. This method avoids extra imaging and radiation, offering a simpler alternative for assessing myocardial viability.
Area of Science:
- Cardiology
- Nuclear Medicine
- Medical Imaging
Background:
- Thallium reinjection enhances detection of ischemic myocardium but requires extra imaging and radiotracer.
- Quantitative analysis of thallium-201 washout offers an alternative without additional patient burden.
Purpose of the Study:
- To evaluate if quantitative regional thallium washout analysis can predict the success of thallium reinjection.
Main Methods:
- Analyzed thallium-201 images from 31 patients with persistent perfusion defects who underwent reinjection.
- Calculated the delayed/initial ratio of radioactive counts in myocardial segments with initial defects.
Main Results:
- A delayed/initial ratio >= 0.75 accurately predicted improvement after reinjection (98% sensitivity, 91% specificity).
- The ratio of 1.06 +/- 0.22 in improved segments contrasted with 0.58 +/- 0.18 in non-improved segments (p < 0.001).
Conclusions:
- Quantitative thallium washout analysis is a reliable predictor of thallium reinjection outcomes.
- This method can guide treatment decisions for patients with coronary artery disease and persistent perfusion defects.
Abstract:
Thallium reinjection can improve the detection of severely ischemic viable myocardium in patients with coronary artery disease. However, a disadvantage of this method is that it requires the acquisition of 3 separate sets of images and the administration of an additional dose of the radiotracer. Alternatively, quantitative analysis of the regional myocardial washout of thallium-201 can be easily obtained from the conventional postexercise and redistribution images without additional imaging time or radiation exposure to the patient. To determine whether this method can predict the results of thallium reinjection, this study analyzed thallium-201 images of 31 patients who had persistent perfusion defects in qualitative exercise/delayed redistribution single-photon emission computed tomographic thallium studies and who underwent thallium reinjection. The quantitative mean radioactive counts of each myocardial segment that had a persistent perfusion defect in the initial and delayed redistribution on 4-hour short-axis tomographic slices were measured to derive a delayed/initial ratio, and these values were compared with the results of thallium reinjection. The delayed/initial ratio was 1.06 +/- 0.22 in 39 segments that improved, versus 0.58 +/- 0.18 in 43 segments without improvement after reinjection (p < 0.001). Thirty-eight of the 39 segments that improved had a ratio of > or = 0.75, versus only 3 of the 43 segments that showed no improvement (sensitivity, 98%; specificity, 91%). The correlation between the delayed/initial ratio and reinjection results was equally high at any segment location or severity. It is concluded that quantitative regional thallium washout analysis predicts the results of thallium reinjection in segments with persistent thallium defects.(ABSTRACT TRUNCATED AT 250 WORDS)