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Updated: Feb 22, 2026
High-Resolution Cardiac Positron Emission Tomography/Computed Tomography for Small Animals
Published on: December 16, 2022
CT-based SPECT attenuation correction and assessment of infarct size: results from a cardiac phantom study
Alexander Stephan Kroiss1,2, Stephan Gerhard Nekolla3, Georg Dobrozemsky4
1Department of Nuclear Medicine, Medical University Innsbruck, Innsbruck, Austria. alexander.kroiss@i-med.ac.at.
Insights
Attenuation Correction (AC) in Cardiac SPECT/CT improves the accuracy of myocardial infarct size quantification. This phantom study demonstrates AC
Area of Science:
- Nuclear medicine imaging
- Cardiovascular diagnostics
- Medical physics
Background:
- Myocardial perfusion SPECT is crucial for coronary artery disease management.
- Photon attenuation in SPECT hinders accurate infarct size quantification.
- CT-Attenuation Correction (AC) offers a potential solution to improve SPECT accuracy.
Purpose of the Study:
- To investigate the impact of CT-Attenuation Correction (AC) on infarct size delineation in myocardial perfusion SPECT.
- To determine optimal thresholding parameters for accurate defect size quantification with and without AC.
- To evaluate the effect of AC on reducing variability in infarct size estimation.
Main Methods:
- Utilized a thorax phantom with simulated myocardial defects (5-20% LV) and varying 99mTc activity.
- Acquired SPECT/CT data using different view/orbit configurations.
- Reconstructed images with scatter correction and resolution recovery, generating polar maps.
- Calculated defect sizes using variable thresholds (40-60%) and identified optimal settings for AC and non-AC data.
Main Results:
- AC enabled accurate estimation of transmural defect extents with a 50% threshold (vs. 40% for non-AC).
- For non-transmural defects, AC yielded optimal results at 55% threshold (vs. 45% for non-AC).
- AC reduced defect size variability due to location by 50%, highlighting its benefit.
Conclusions:
- Cardiac SPECT/CT with attenuation correction significantly enhances quantitative assessment of myocardial defect sizes.
- AC improves the reliability and accuracy of infarct size measurements in phantom studies.
- The findings support the clinical utility of AC in SPECT/CT for improved cardiac diagnostics.
Rationale:
Myocardial perfusion SPECT is a commonly performed, well established, clinically useful procedure for the management of patients with coronary artery disease. However, the attenuation of photons from myocardium impacts the quantification of infarct sizes. CT-Attenuation Correction (AC) potentially resolves this problem. This contention was investigated by analyzing various parameters for infarct size delineation in a cardiac phantom model.
Methods:
A thorax phantom with a left ventricle (LV), fillable defects, lungs, spine and liver was used. The defects were combined to simulate 6 infarct sizes (5-20% LV). The LV walls were filled with 100120 kBq/ml 99mTc and the liver with 10-12 kBq/ml 99mTc. The defects were filled with water of 50% LV activity to simulate transmural and non-transmural infarction, respectively. Imaging of the phantom was repeated for each configuration in a SPECT/CT system. The defects were positioned in the anterior as well as in the inferior wall. Data were acquired in two modes: 32 views, 30 s/view, 180° and 64 views, 15 s/view, 360° orbit. Images were reconstructed iteratively with scatter correction and resolution recovery. Polar maps were generated and defect sizes were calculated with variable thresholds (40-60%, in 5% steps). The threshold yielding the best correlation and the lowest mean deviation from the true extents was considered optimal.
Results:
AC data showed accurate estimation of transmural defect extents with an optimal threshold of 50% [non attenuation correction (NAC): 40%]. For the simulation of non-transmural defects, a threshold of 55% for AC was found to yield the best results (NAC: 45%). The variability in defect size due to the location (anterior versus inferior) of the defect was reduced by 50% when using AC data indicating the benefit from using AC. No difference in the optimal threshold was observed between the different orbits.
Conclusion:
Cardiac SPECT/CT shows an improved capability for quantitative defect size assessment in phantom studies due to the positive effects of attenuation correction.
