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Updated: Jun 28, 2026
In Vivo Quantitative Assessment of Myocardial Structure, Function, Perfusion and Viability Using Cardiac Micro-computed Tomography
Published on: February 16, 2016
Comparison of thallium deposition with segmental perfusion in pigs with chronic hibernating myocardium
Sunil Baldwa1, Muzamil Rana, John M Canty
1Veterans Affairs Western New York Health Care System at Buffalo, Buffalo, NY 14214, USA.
Insights
Thallium-201 imaging may overestimate myocardial viability in hibernating heart muscle within one hour. This imaging technique may not distinguish hibernating myocardium from dysfunctional myocardium with normal resting flow, impacting clinical decisions.
Area of Science:
- Cardiology
- Nuclear Medicine
- Medical Imaging
Background:
- Hibernating myocardium, viable but dysfunctional heart muscle with reduced resting flow, is a key prognostic factor in ischemic heart disease.
- Thallium-201 (Tl-201) scintigraphy is commonly used to assess myocardial viability, but its deposition patterns in hibernating myocardium require further investigation.
- Existing data suggest potentially supernormal Tl-201 retention in hibernating myocardium compared to controls.
Purpose of the Study:
- To evaluate the deposition characteristics of thallium-201 in chronically dysfunctional, hibernating myocardium in a porcine model.
- To compare thallium-201 uptake with myocardial perfusion and glucose metabolism (FDG) in hibernating versus remote myocardium.
- To determine the temporal dynamics of thallium-201 redistribution within the first hour in hibernating myocardium.
Main Methods:
- A porcine model of chronic hibernating myocardium was created using a left anterior descending coronary artery stenosis.
- Myocardial viability was assessed using thallium-201 and [18F]-2-fluoro-2-deoxyglucose (FDG) uptake over 1 hour.
- Myocardial perfusion was quantified using microspheres, and wall motion was assessed via contrast ventriculography.
- Histology was used to confirm myocardial viability.
Main Results:
- Thallium-201 deposition showed only a weak correlation with regional myocardial perfusion (r2=0.20).
- Thallium-201 was more homogeneously distributed in hibernating myocardium compared to microsphere-measured flow.
- Within 1 hour, relative thallium-201 uptake overestimated relative perfusion, suggesting near-complete redistribution and potentially masking flow deficits.
Conclusions:
- Under resting conditions, thallium-201 redistribution in hibernating myocardium is largely complete within 1 hour.
- Thallium-201 deposition at 1 hour may not reliably differentiate hibernating myocardium from dysfunctional myocardium with normal resting flow.
- This limitation in thallium-201 imaging could have significant clinical implications for prognostic assessment in ischemic heart disease.
Abstract:
Viable, chronically dysfunctional myocardium with reduced resting flow (or hibernating myocardium) is an important prognostic factor in ischemic heart disease. Although thallium-201 imaging is frequently used to assess myocardial viability in patients with ischemic cardiomyopathy, there are limited data regarding its deposition in hibernating myocardium, and this data suggest that thallium retention may be supernormal compared with control myocardium. Accordingly, pigs (n=7) were chronically instrumented with a 1.5 mm Delrin stenosis on the proximal left anterior descending coronary artery (LAD) to produce hibernating myocardium. Four months later, severe anteroapical hypokinesis was documented with contrast ventriculography (wall motion score, 0.7+/-0.8; normal=3), and microsphere measurements confirmed reduced resting flow (LAD subendocardium, 0.78+/-0.34 vs. 0.96+/-0.24 ml.min(-1).g(-1) in remote; P<0.001). Absolute deposition of thallium-201 and insulin-stimulated [18F]-2 fluoro-2-deoxyglucose (FDG) were assessed over 1 h and compared with resting flow (n=704 samples). Thallium-201 deposition was only weakly correlated with perfusion (r2=0.20; P<0.001) and was more homogeneously distributed (relative dispersion, 0.12+/-0.03 vs. 0.29+/-0.10 for microsphere flow; P<0.01). Thus after 1 h relative thallium-201 (subendocardium LAD/remote, 0.96+/-0.16) overestimated relative perfusion (0.78+/-0.32; P<0.0001) and underestimated the relative reduction in flow. Viability was confirmed by both histology and preserved FDG uptake. We conclude that under resting conditions, thallium-201 redistribution in hibernating myocardium is nearly complete within 1 h, with similar deposition to remote myocardium despite regional differences in flow. These data suggest that in this time frame thallium-201 deposition may not discriminate hibernating myocardium from dysfunction myocardium with normal resting flow. Since hibernating myocardium has been associated with a worse prognosis, this limitation could have significant clinical implications.
