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Updated: May 29, 2026
In Vivo Quantitative Assessment of Myocardial Structure, Function, Perfusion and Viability Using Cardiac Micro-computed Tomography
Published on: February 16, 2016
MRI study on volume effects of coronary emboli on myocardial function, perfusion and viability
Maythem Saeed1, Steven W Hetts, Loi Do
1Interventional Radiology Laboratory, Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA, United States. Maythem.saeed@ucsf.edu
Background:
Coronary filtration devices showed inadequate protection during PCI due to the inability to filter microemboli <120 μm in diameter. The purpose of this study was to determine the impact of two volumes of <120 μm microemboli on LV function, perfusion and viability using magnetic resonance imaging (MRI).
Methods:
Under X-ray guidance, pigs (n = 18) received two different volumes (16 mm(3) or 32 mm(3)) of 40-120 μm microemboli (intracoronary). At 3 days, regional myocardial perfusion and LV function were assessed using first pass perfusion and cine MRI. Viability MRI was performed in beating and non-beating hearts to delineate microinfarcts and compare with histochemical triphenyltetrazolium chloride stain, using semi-automatic threshold method. Histology and cardiac injury enzymes were used to confirm the presence of microinfarcts and characterize cellular and vascular changes.
Results:
Microinfarcts were visible as enhanced specks on DE-MRI in all animals that received 32 mm(3), but only two-third of the animals that received 16 mm(3), volume. The decline in ejection fraction and increase in LV volumes and microinfarcts were volume dependent. Regional perfusion and contractility were significantly reduced in the LAD territory compared with remote myocardium. Histology showed apoptosis, edema, inflammation and vascular thrombosis.
Conclusions:
Microemboli of <120 μm have deleterious effects on LV function, perfusion and viability and the effects are dependent on microemboli volume. Microinfarct visualization is crucial to ensure that myocardial dysfunction is related to dislodged microemboli and not only to pre-procedural stunning or hibernation. This noninvasive MRI method may help in evaluating the effectiveness of coronary filtration devices in protecting myocardium from microemboli.
Insights
Microemboli smaller than 120 μm negatively impact left ventricular (LV) function and perfusion. The severity of these effects, including microinfarcts, is directly related to the volume of microemboli administered.
Area of Science:
- Cardiovascular Research
- Medical Imaging
- Interventional Cardiology
Background:
- Coronary filtration devices offer inadequate protection against microemboli <120 μm during percutaneous coronary intervention (PCI).
- Understanding the impact of small microemboli on cardiac function is crucial for improving PCI safety.
Purpose of the Study:
- To determine the impact of two volumes of <120 μm microemboli on left ventricular (LV) function, perfusion, and viability.
- To assess the utility of magnetic resonance imaging (MRI) in visualizing microinfarcts.
Main Methods:
- Pigs (n=18) received intracoronary infusions of 16 mm³ or 32 mm³ of 40-120 μm microemboli.
- LV function, perfusion, and viability were assessed using MRI at 3 days.
- Histology and cardiac enzymes were used for confirmation and characterization of microinfarcts.
Main Results:
- Microinfarcts were visualized on DE-MRI in all animals receiving 32 mm³ and two-thirds receiving 16 mm³.
- A volume-dependent decline in ejection fraction and increase in LV volumes and microinfarcts were observed.
- Regional perfusion and contractility were reduced in the left anterior descending (LAD) territory; histology revealed apoptosis, edema, inflammation, and thrombosis.
Conclusions:
- Microemboli <120 μm have detrimental, volume-dependent effects on LV function, perfusion, and viability.
- MRI visualization of microinfarcts is essential for attributing myocardial dysfunction to microemboli.
- This noninvasive MRI approach can aid in evaluating coronary filtration device efficacy.
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