Sodium MRI in human heart: a review

Area of Science:

• Cardiovascular Magnetic Resonance Imaging
• Biophysical Chemistry

Background:

• Sodium-23 (23Na) MRI is a developing technique for assessing heart tissue.
• The low signal-to-noise ratio and complex relaxation properties of 23Na present significant technical challenges for cardiac imaging.
• Conventional hydrogen-1 (1H) MRI has limitations in quantifying tissue sodium concentration.

Purpose of the Study:

• To critically review the properties, methods, and clinical applications of sodium-23 MRI in the human heart.
• To evaluate the potential of 23Na MRI for diagnosing and monitoring cardiac diseases.

Main Methods:

• Utilizes specialized, ultra-short echo-time MRI sequences to overcome rapid relaxation times of 23Na.
• Studies conducted across a range of magnetic field strengths (1.5 to 7 T).
• Measures volume-weighted intra- and extra-cellular sodium concentrations.

Main Results:

• Demonstrated increases in tissue sodium concentration in human myocardial infarction, consistent with animal studies.
• Identified potential for detecting sodium changes in ischemia and cardiomyopathies.
• Current methods measure a combined intra- and extra-cellular sodium signal without unambiguous resolution.

Conclusions:

• Cardiac 23Na MRI shows promise for detecting myocardial infarction and other heart conditions involving sodium transport defects.
• Technical hurdles in implementation and signal acquisition need to be overcome.
• The clinical utility hinges on providing unique information not accessible through conventional methods like 1H MRI.