Superparamagnetic iron oxide MION as a contrast agent for sodium MRI in myocardial infarction

Area of Science:

• Cardiovascular Imaging
• Magnetic Resonance Imaging
• Biomedical Engineering

Background:

• Sodium-23 Magnetic Resonance Imaging (23Na MRI) offers unique insights into tissue physiology.
• Suppressing blood signal in 23Na MRI is crucial for visualizing myocardial tissue, especially in infarction.
• Iron-based contrast agents are being explored for their relaxivity properties.

Purpose of the Study:

• To evaluate an iron-based contrast agent as a sodium (23Na) MRI T2 relaxant.
• To suppress blood signal in ventricular cavities of normal and infarcted canine myocardium in vivo.
• To assess the agent's efficacy in delineating myocardial infarction.

Main Methods:

• Intravascular administration of an iron-based contrast agent in canine models.
• Sodium-23 (23Na) MRI T2 relaxometry was performed at varying doses and echo times (TE).
• Signal decreases in blood were quantified, and contrast-to-noise ratios were compared pre- and post-contrast injection.

Main Results:

• Significant decreases in 23Na MRI blood signal (up to 65%) were observed with 10 mg/kg dose and 5 ms TE.
• Signal reduction was attributed to changes in fast (T2f) and slow (T2s) transverse relaxation components.
• Clear delineation of infarcted tissue was achieved, with up to a 3.3-fold improvement in contrast-to-noise ratio.

Conclusions:

• Iron-based contrast agents can serve as effective 23Na MRI T2 relaxants.
• This approach successfully suppresses blood signal, enhancing visualization of myocardial infarction.
• The method improves diagnostic accuracy by increasing contrast between blood and infarcted tissue.