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Relation between myocardial thallium-201 kinetics during exercise and quantitative coronary angiography in patients
S Hadjimiltiades1, R Watson, A H Hakki
1Philadelphia Heart Institute, Presbyterian-University of Pennsylvania Medical Center 19104.
Insights
Thallium-201 kinetics accurately reflect coronary artery stenosis severity in patients with one-vessel disease. Myocardial thallium concentration and washout ratios correlate better with minimal diameter and area stenosis, especially without collateral vessels.
Area of Science:
- Cardiology
- Nuclear Medicine
- Medical Imaging
Background:
- Coronary artery disease (CAD) diagnosis relies on assessing stenosis severity.
- Thallium-201 (Tl-201) scintigraphy is used to evaluate myocardial perfusion.
- The relationship between Tl-201 kinetics and coronary stenosis severity requires further elucidation, particularly concerning collateral flow.
Purpose of the Study:
- To investigate the correlation between Tl-201 kinetics and coronary stenosis in patients with one-vessel CAD.
- To determine if collateral vessels influence the relationship between Tl-201 kinetics and stenosis severity.
- To compare the correlation of Tl-201 ratios with different measures of coronary stenosis.
Main Methods:
- Thirty patients with one-vessel CAD underwent Tl-201 scintigraphy post-exercise.
- Myocardial Tl-201 concentration and washout ratios were calculated for diseased and normal vessels.
- Coronary stenosis was quantified using minimal diameter, minimal area, and percent diameter stenosis.
Main Results:
- Correlations between Tl-201 ratios and stenosis descriptors improved in patients without collateral vessels.
- Significant correlations were found between myocardial concentration ratio and minimal diameter (r=0.73) and area stenosis (r=0.72).
- Washout ratio also correlated significantly with minimal diameter (r=0.50) and area stenosis (r=0.45).
Conclusions:
- Tl-201 kinetics, specifically myocardial concentration and washout ratios, are reliable indicators of perfusion deficits in one-vessel CAD.
- These kinetic parameters correlate better with minimal diameter and area stenosis than percent diameter stenosis.
- The presence of collateral vessels can influence the assessment of stenosis severity using Tl-201 kinetics.
Abstract:
This study examined the relation between the kinetics of thallium-201 and coronary stenosis in 30 patients with one vessel coronary artery disease; 25 patients had no visible collateral vessels. The myocardial thallium concentration in the postexercise images and percent washout were determined in the distribution of the diseased vessel and a normal vessel, and each was expressed as a ratio. Coronary stenosis was assessed as minimal diameter stenosis, minimal area stenosis and percent diameter stenosis. The correlations between the myocardial concentration ratio or washout ratio and the descriptors of coronary stenosis improved when the patients with collateral vessels were excluded. There were significant correlations between the myocardial thallium concentration ratio and minimal diameter stenosis (r = 0.73, p less than 0.001), minimal area stenosis (r = 0.72, p less than 0.001) and, to a lesser degree, percent diameter stenosis (r = -0.51, p less than 0.01). Similarly, there were significant correlations between washout ratio and minimal diameter stenosis (r = 0.50, p less than 0.01) and minimal area stenosis (r = 0.45, p less than 0.02) but not percent diameter stenosis (r = 0.37, p = 0.06). Thus, variation in thallium kinetics in relation to the severity of coronary stenosis can be demonstrated with conventional imaging in patients with one vessel disease. The myocardial thallium concentration and washout are physiologic expressions of the severity of perfusion deficit and are dependent on collateral flow. The myocardial thallium concentration ratio and washout ratio correlate better with minimal diameter and area stenosis than with percent diameter stenosis.