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Thallium scintigraphy compared with 18F-fluorodeoxyglucose positron emission tomography for assessing myocardial
J A Marin-Neto1, V Dilsizian, J A Arrighi
1Cardiology Branch, National Heart, Lung, and Blood Institute, Bethesda, Maryland, USA.
Insights
Thallium-201 reinjection imaging shows high concordance with PET for assessing myocardial viability in coronary artery disease patients with moderate to severe left ventricular dysfunction. Concordance decreases for severe perfusion defects in severely impaired ventricles.
Area of Science:
- Cardiology
- Nuclear Medicine
- Medical Imaging
Background:
- Assessing myocardial viability is crucial for managing coronary artery disease (CAD) with left ventricular (LV) dysfunction.
- Thallium-201 SPECT and Positron Emission Tomography (PET) are used to evaluate myocardial viability.
- Previous studies suggest concordance between these methods, but data in severe LV dysfunction are limited.
Purpose of the Study:
- To compare the concordance of Thallium-201 reinjection SPECT and PET for assessing myocardial viability.
- To investigate if concordance differs between moderate and severe LV dysfunction in patients with chronic CAD.
Main Methods:
- 44 patients with chronic CAD and LV dysfunction were studied.
- Patients were subgrouped into moderate (n=23) and severe (n=21) LV dysfunction.
- Exercise Thallium-201 SPECT with redistribution and reinjection, and 18-fluorodeoxyglucose/15O-water PET were performed.
- Quantitative analysis of aligned tomograms was conducted.
Main Results:
- Thallium SPECT and PET showed high concordance (98% moderate LV dysfunction, 93% severe LV dysfunction) in assessing myocardial viability.
- Lower concordance was observed for regions with severe irreversible thallium perfusion defects (86% moderate, 78% severe LV dysfunction).
- Discordance exceeded 20% in severely impaired LV regions with irreversible defects.
Conclusions:
- Thallium-201 SPECT with reinjection provides information on regional myocardial viability similar to PET.
- This concordance holds for both moderate and severe LV dysfunction.
- Caution is advised when interpreting severe irreversible thallium defects in patients with severely reduced LV function due to potential discordance.
Abstract:
Thallium-201 reinjection imaging and positron emission tomography provide concordant information regarding myocardial viability in many patients with coronary artery disease and left ventricular (LV) dysfunction. It is unclear whether this concordance applies to patients with severe, as well as those with moderate, LV dysfunction. We studied 44 patients with chronic coronary artery disease and LV dysfunction, subgrouped on the basis of severity of dysfunction: 23 patients had moderate and 21 had severe dysfunction (ejection fractions 34 +/- 6% and 19 +/- 6%). Patients underwent exercise thallium single-photon emission computed tomography (SPECT) with 3- to 4-hour redistribution and reinjection imaging, as well as positron emission tomography (PET) imaging with 18fluorodeoxyglucose and 15O-water. Data were analyzed quantitatively in aligned transaxial PET and SPECT tomograms. A myocardial region was considered nonviable by PET if 18fluorodeoxyglucose activity was <50% of that in a normal region, associated with proportional reduction in blood flow. Similarly, regions were considered nonviable by thallium if activity was <50% of activity in normal regions on redistribution and reinjection studies. Thallium SPECT and PET data were concordant regarding viability in 98% and 93% of myocardial regions, respectively, in patients with moderate and with severe LV dysfunction. Lower concordance was observed only when regions with severe irreversible thallium perfusion defects on redistribution images were considered in both groups: 86% and 78%, respectively (p <0.01). Thus, thallium SPECT with reinjection yields information regarding regional myocardial viability that is similar to that provided by PET in patients with severe as well as moderate LV dysfunction. However, there is discordance in >20% of regions manifesting severe irreversible thallium defects in patients with severely reduced LV function.