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Quantitative severity of stress thallium-201 myocardial perfusion single-photon emission computed tomography defects
L Matzer1, H Kiat, K Van Train
1Department of Medicine (Division of Cardiology), Cedars-Sinai Medical Center, Los Angeles, California 90048.
Insights
Exercise thallium-201 SPECT (single-photon emission computed tomography) effectively quantifies myocardial perfusion defect severity. This score strongly correlates with coronary artery stenosis, aiding in noninvasive assessment of functionally significant blockages.
Area of Science:
- Cardiovascular Imaging
- Nuclear Cardiology
- Coronary Artery Disease
Background:
- Coronary artery stenosis assessment often relies on invasive coronary angiography.
- Noninvasive methods are sought to complement or guide angiographic evaluation.
- Exercise thallium-201 SPECT is a nuclear imaging technique used to assess myocardial perfusion.
Purpose of the Study:
- To examine the relationship between quantitative myocardial perfusion defect severity on exercise thallium-201 SPECT and the degree of coronary stenosis.
- To determine if thallium-201 SPECT can noninvasively characterize the functional severity of coronary artery stenosis.
Main Methods:
- 18 patients with 1-vessel disease and abnormal thallium-201 SPECT were analyzed.
- Quantitative defect severity score derived from thallium-201 SPECT by measuring pixel counts below normal mean.
- Comparison of SPECT scores with quantitative angiographic indexes of stenosis (percent diameter and area narrowing).
Main Results:
- Thallium-201 SPECT defect severity score showed significant correlation with maximal percent luminal diameter narrowing (r=0.93) and percent area narrowing (r=0.89).
- Strongest correlations were observed at low and high ranges of stenosis; moderate ranges (50-80% diameter stenosis) showed more variability.
- Findings suggest thallium-201 SPECT defect severity can characterize functional severity of coronary stenosis.
Conclusions:
- Quantitative thallium-201 SPECT defect severity is a valuable noninvasive tool for assessing coronary artery stenosis.
- This technique may complement coronary angiography in identifying functionally significant stenotic lesions.
- Further research may explore its utility in select patient populations.
Abstract:
The relation between the quantitative myocardial perfusion defect severity of exercise thallium-201 single-photon emission computed tomography (SPECT) and the quantitative degree of coronary stenosis was examined in 18 patients with 1-vessel disease (> or = 50% diameter stenosis), and abnormal thallium-201 SPECT. A total of 26 vessels were analyzed. Thallium-201 SPECT quantitative defect severity score was derived by summing the number of pixels in a coronary territory in which counts fell below the normal mean and multiplied by the number of SDs by which they fell below the normal mean. The thallium-201 defect severity score was significantly (p < 0.001) related to the maximal percent luminal diameter narrowing (r = 0.93), percent area narrowing (r = 0.89), absolute stenotic area (r = 0.79), and absolute stenotic diameter (r = 0.81). As expected, the strongest relation between thallium-201 defect severity and quantitative angiographic indexes was in the low and high ranges of coronary stenosis, with more variability and lower correlation coefficients (percent diameter: r = 0.75, p < 0.02, percent area stenosis: r = 0.63, p < 0.05) in the middle ranges (50 to 80% diameter stenosis). This observation is likely to be due to the complex flow characteristics across stenotic lesions. The findings suggest that in a select population, thallium-201 defect severity is potentially useful for noninvasive characterization of the functional severity of coronary artery stenosis and may complement coronary angiography in predicting functionally significant stenosis.