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Delayed redistribution in thallium 201 SPECT myocardial perfusion studies
H A Ziessman1, J W Keyes, L M Fox
1Department of Radiology, Georgetown University Medical Center, Washington, D.C. 20007.
Chest
|November 1, 1989
Summary
Delayed redistribution in thallium-201 myocardial perfusion imaging is common, occurring in 31% of patients. This finding suggests viability in areas with initially fixed defects, impacting treatment decisions for coronary artery disease.
Area of Science:
- Cardiology
- Nuclear Medicine
- Diagnostic Imaging
Background:
- Stress thallium-201 (201Tl) myocardial perfusion imaging differentiates ischemic from infarcted myocardium.
- Redistribution at 2-4 hours indicates ischemia; fixed defects suggest infarction.
- Delayed redistribution at 24 hours can occur in some patients with fixed defects.
Purpose of the Study:
- Evaluate the frequency and significance of delayed redistribution with SPECT 201Tl.
- Assess the utility of delayed imaging in patients with non-redistributing defects at 4 hours.
Main Methods:
- Patients with no or incomplete redistribution at 4-hour SPECT 201Tl imaging underwent repeat imaging 18-48 hours later.
- Analysis focused on identifying delayed redistribution in these selected patient groups.
Main Results:
- Delayed redistribution was observed in 8 out of 26 patients (31%).
- This included four patients with incomplete and four with no redistribution at the 4-hour scan.
- Delayed redistribution is more frequent than typically recognized.
Conclusions:
- Delayed redistribution with SPECT 201Tl is a significant finding, suggesting myocardial viability.
- Recommend delayed imaging (18-48 hours) for patients with fixed or incomplete perfusion defects at 4 hours.
- This is particularly important for patients with prior infarctions considered for revascularization.