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[Noninvasive identification of collateralized myocardium by 201 thallium tomography in vasodilation and
C A Nienaber1, R P Spielmann, D Salge
1Division of Nuclear Medicine & Biophysics, UCLA School of Medicine.
Insights
Dipyridamole thallium-201 SPECT imaging can identify collateral circulation in postinfarction patients. This technique helps quantify jeopardized myocardium, aiding diagnostic and therapeutic decisions for coronary artery disease.
Area of Science:
- Cardiology
- Nuclear Medicine
- Medical Imaging
Background:
- Coronary collateral channels play a crucial role in supplying blood flow to jeopardized myocardium, especially after myocardial infarction.
- Assessing the functional significance of these collateral channels is vital for understanding myocardial viability and guiding treatment strategies.
Purpose of the Study:
- To evaluate the physiological significance of coronary collateral channels in postinfarction patients.
- To determine if vasodilatation/redistribution thallium-201 SPECT imaging can identify and quantify collateral-dependent myocardium.
Main Methods:
- Eighty postinfarction patients underwent dipyridamole thallium-201 SPECT imaging.
- Circumferential profile analysis quantified transient and persistent perfusion defects.
- Correlations were made with cineangiography and collateral circulation assessment.
Main Results:
- Patients with visible collaterals showed larger distant reversible defects and greater overall redistribution compared to those without collaterals.
- The size of persistent perfusion defects was similar between groups.
- The tomographic perfusion pattern demonstrated 85% sensitivity and 78% specificity for detecting significant collateral circulation.
Conclusions:
- Vasodilatation/redistribution thallium-201 tomography is a valuable tool for identifying and quantifying collateral-dependent myocardium.
- This imaging modality has potential in guiding diagnostic and therapeutic decision-making for patients with coronary artery disease.
Abstract:
Coronary arteriolar vasodilatation may provoke the redistribution of flow to collateral-dependent jeopardized myocardium. To assess the physiologic significance of collateral channels, 80 consecutive postinfarction patients (aged: 58 +/- 8 years) underwent vasodilatation/redistribution thallium-201 tomographic (SPECT) imaging using 0.56 mg dipyridamole/kg body weight. Circumferential profile analysis of redistribution and slow washout in representative left ventricular tomograms provided quantitative evaluation of transient and persistent defects and a separation between a periinfarctional and distant inducible hypoperfusion. Tomographic perfusion data were correlated to subsequent cineangiographic analysis of wall motion and to the extent of collateral circulation between two distinct anatomic perfusion areas, one of which involved the infarct zone. Patients were grouped according to the presence (59%) or absence (41%) of angiographically visible collateral channels to the jeopardized myocardium. In the presence of collaterals, distant reversible defects were larger than in the absence of collaterals (p less than 0.05); the extent of combined periinfarctional and distant redistribution was also larger in collateralized patients (p less than 0.025), whereas the size of the persistent perfusion defect was similar in both groups. In a prospective analysis, the tomographic perfusion pattern of combined periinfarctional and distant ischemia revealed a sensitivity of 85% and a specificity of 78% for the detection of significant collateral circulation in this group of patients. Thus, using the limited collateral flow reserve as a diagnostic tool, vasodilatation/redistribution thallium-201 tomography has some potential for identifying and quantifying collateral-dependent myocardium and may guide diagnostic and therapeutic decision-making.