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Multislice first-pass cardiac perfusion MRI: validation in a model of myocardial infarction
Frederick H Epstein1, James F London, Dana C Peters
1Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA. fhe6b@virginia.edu
Abstract:
The purpose of this study was to validate a first-pass MRI method for imaging myocardial perfusion with multislice coverage and relatively small analyzable regions of interest (ROIs). A fast gradient-echo (FGRE) sequence with an echo-train (ET) readout was used to achieve multislice coverage, and a high dose of a contrast agent (CA) was used to achieve a high signal-to-noise ratio (SNR). Dogs (N = 6) were studied 1 day after reperfused myocardial infarction, and fluorescent microspheres were used as a standard for perfusion. First-pass MRI correlated well vs. microsphere flow, achieving mean R values of 0.87 (range = 0.82-0.93), 0.71 (range = 0.46-0.85), and 0.72 (range = 0.49-0.95) for subendocardial ROIs, transmural ROIs, and the endocardial-epicardial ratio, respectively. Additionally, analysis of myocardial time-intensity curves (TICs) indicated that 15.8 +/- 6 sectors, corresponding to 260 microl of endocardium, can be analyzed (R(2) > 0.95).
Insights
This study validates a first-pass MRI method for assessing myocardial perfusion. The technique accurately measures blood flow in small regions, offering a reliable tool for diagnosing heart conditions.
Area of Science:
- Cardiovascular Imaging
- Magnetic Resonance Imaging
- Myocardial Perfusion Assessment
Background:
- Assessing myocardial perfusion is crucial for diagnosing and managing ischemic heart disease.
- Existing methods for myocardial perfusion imaging may have limitations in resolution or coverage.
- First-pass MRI offers potential for rapid, multislice assessment of blood flow.
Purpose of the Study:
- To validate a first-pass MRI technique for imaging myocardial perfusion.
- To assess the method's ability to provide multislice coverage and analyze small regions of interest (ROIs).
- To compare MRI-derived perfusion measurements with a gold standard method.
Main Methods:
- Utilized a fast gradient-echo (FGRE) sequence with echo-train (ET) readout for multislice coverage.
- Administered a high dose of contrast agent (CA) to enhance signal-to-noise ratio (SNR).
- Studied 6 dogs 1 day after reperfused myocardial infarction, using fluorescent microspheres as the standard for perfusion.
Main Results:
- First-pass MRI showed strong correlation with microsphere flow measurements.
- Mean R values were 0.87 for subendocardial ROIs, 0.71 for transmural ROIs, and 0.72 for the endocardial-epicardial ratio.
- Analysis of myocardial time-intensity curves (TICs) demonstrated that 15.8 ± 6 sectors (260 μl of endocardium) could be reliably analyzed (R² > 0.95).
Conclusions:
- The validated first-pass MRI method provides accurate and reliable assessment of myocardial perfusion.
- The technique enables multislice coverage and analysis of small myocardial regions.
- This method holds promise for improved diagnosis and management of myocardial perfusion abnormalities.