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Contrast-enhanced magnetic resonance imaging of hypoperfused myocardium
S Schaefer1, R A Lange, D P Gutekunst
1Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas.
Abstract:
Contrast-enhanced magnetic resonance (MR) imaging can define myocardial perfusion defects due to acute coronary occlusion. However, since most clinically important diagnostic examinations involve coronary arteries with subtotal stenoses, we investigated the ability of MR imaging with a manganese contrast agent to detect perfusion abnormalities in a canine model of partial coronary artery stenosis. The contrast agent was administered after the creation of a partial coronary artery stenosis with the addition of the coronary vasodilator dipyridamole in six of 12 animals. The hearts were imaged ex situ using gradient reversal and spin-echo sequences, and images were analyzed to determine differences in signal intensity between hypoperfused and normally perfused myocardium. Comparison of MR images with regional blood flow and thallium-201 measurements showed good concordance of hypoperfused segments in those animals given dipyridamole, with 75% of the abnormal segments correctly identified. In those animals not given dipyridamole, 48% of segments were correctly identified. Thus, ex vivo MR imaging with a paramagnetic contrast enhancement can be used to detect acute regional myocardial perfusion abnormalities due to severe partial coronary artery stenoses.
Insights
Magnetic resonance (MR) imaging with manganese contrast agents can detect myocardial perfusion defects. This study shows MR imaging effectively identifies abnormalities in partial coronary artery stenosis, aiding diagnosis.
Area of Science:
- Cardiovascular imaging
- Medical physics
- Diagnostic radiology
Background:
- Contrast-enhanced magnetic resonance (MR) imaging is valuable for identifying myocardial perfusion defects caused by acute coronary occlusion.
- Clinically significant diagnoses often involve coronary arteries with subtotal stenoses, necessitating methods to detect these specific conditions.
Purpose of the Study:
- To investigate the efficacy of MR imaging with a manganese contrast agent in detecting perfusion abnormalities in a canine model.
- To assess MR imaging's ability to identify perfusion defects in cases of partial coronary artery stenosis.
Main Methods:
- A canine model of partial coronary artery stenosis was established.
- A manganese contrast agent was administered, with dipyridamole (a coronary vasodilator) used in half the animals.
- Ex vivo hearts were imaged using gradient reversal and spin-echo sequences.
- MR image signal intensities were analyzed to differentiate hypoperfused from normally perfused myocardium.
Main Results:
- MR imaging showed good concordance with regional blood flow and thallium-201 measurements.
- In animals given dipyridamole, 75% of abnormal myocardial segments were correctly identified.
- In animals without dipyridamole, 48% of abnormal segments were correctly identified.
Conclusions:
- Ex vivo MR imaging utilizing paramagnetic contrast enhancement can detect acute regional myocardial perfusion abnormalities.
- This technique is effective in identifying perfusion issues associated with severe partial coronary artery stenoses.