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Quantifying transient ischemic dilation using gated SPECT.
Thomas F Heston1, Daniel M Sigg
1Northwest Molecular, Kellogg, Idaho 83837, USA. heston@nwmolecular.com
Summary
Transient ischemic dilation (TID) is a key indicator of coronary artery disease. This study found that combining end-systolic volume and end-diastolic volume ratios in a novel stress-induced volume ratio (SIVR) best correlates with myocardial ischemia.
Area of Science:
- Cardiology
- Nuclear Cardiology
- Medical Imaging
Background:
- Transient ischemic dilation (TID) is a sensitive indicator of triple-vessel coronary artery disease, typically assessed using ungated SPECT.
- Gated SPECT allows for detailed measurements of end-diastolic volume (EDV) and end-systolic volume (ESV), enabling a more nuanced analysis of TID.
Purpose of the Study:
- To quantify the relative contributions of EDV and ESV to TID.
- To develop an optimized stress-induced volume ratio (SIVR) for improved correlation with myocardial ischemia.
Main Methods:
- Retrospective review of 422 patients undergoing gated SPECT myocardial perfusion imaging.
- Calculation of post-stress-to-rest ratios for EDV, ESV, and LVEF.
- Empirical assignment of weights to EDV and ESV to derive an SIVR with the strongest correlation to ischemia.
Main Results:
- Significant correlations were found between ischemia and ESV ratio, EDV ratio, and LVEF ratio.
- The ESV ratio demonstrated the strongest correlation with myocardial ischemia when controlling for clinical factors.
- An optimized SIVR, calculated as the stress-to-rest ratio of (ESVx5.0+EDV), showed a stronger correlation with ischemia than individual ratios.
Conclusions:
- Combining ESV and EDV ratios into an SIVR provides a stronger correlation with myocardial ischemia than using either ratio alone.
- The end-systolic volume (ESV) contributes approximately five times more than the end-diastolic volume (EDV) to the SIVR for detecting stress-induced myocardial perfusion defects.