Myocardial Approximate Spin-lock Dispersion Mapping using a Simultaneous T₂ and T_RAFF2 Mapping at 3T MRI

Area of Science:

• Cardiovascular Magnetic Resonance Imaging
• Biomarker Development
• Medical Physics

Background:

• Ischemic heart disease (IHD) is a leading cause of death, with myocardial infarction (MI) accounting for a third of cases.
• Cardiac MRI, particularly Late Gadolinium Enhancement (LGE), assesses MI damage but gadolinium contrast agents have limitations.
• Spin-lock (SL) dispersion is a promising non-contrast alternative, but current methods face challenges at 3T, including Specific Absorption Rate (SAR) limitations and artifacts.

Purpose of the Study:

• To develop and validate a novel, single breath-hold, simultaneous T_RAFF2 and T₂ mapping sequence for spin-lock (SL) dispersion mapping at 3T.
• To overcome SAR limitations and off-resonance artifacts associated with traditional SL preparations.
• To provide a non-contrast MRI method for assessing myocardial viability and fibrosis in patients with MI.

Main Methods:

• Development of a simultaneous T_RAFF2 and T₂ mapping sequence for 3T MRI.
• Acquisition and analysis of data in phantom experiments to assess reproducibility and map quality.
• Comparison of results with reference methods for T_RAFF2, T₂, and SL dispersion values.
• In vivo imaging to evaluate clinical applicability and artifact levels.

Main Results:

• The proposed sequence demonstrated excellent reproducibility in phantom studies (coefficient of variations < 10%).
• Myocardial T_RAFF2, T₂, and SL dispersion values obtained were comparable to reference methods.
• High-quality T₂, T_RAFF2, and SL dispersion maps were achieved in phantoms and in vivo, free from major artifacts.

Conclusions:

• The developed single breath-hold sequence enables accurate and reproducible SL dispersion mapping at 3T.
• This non-contrast approach offers a promising alternative to LGE for assessing MI-related myocardial damage and fibrosis.
• The technique has significant potential for clinical application in MI assessment, improving patient safety and accessibility.