Simultaneous T₁ and T₂ mapping of hyperpolarized ¹³C compounds using the bSSFP sequence

Area of Science:

• Magnetic Resonance Imaging
• Biomedical Engineering
• Nuclear Magnetic Resonance

Background:

• T1 and T2 relaxation times of hyperpolarized (HP) 13C nuclei offer vital biomedical insights, similar to conventional 1H MRI.
• Accurate mapping of these relaxation times is crucial for quantitative HP 13C MRI.
• Existing methods may not provide simultaneous T1 and T2 information efficiently.

Purpose of the Study:

• To develop and validate novel methods for simultaneous T1 and T2 mapping of HP 13C probes.
• To assess the feasibility of these methods in simulations, phantoms, and in vivo studies.
• To enable comprehensive metabolic imaging in a single acquisition.

Main Methods:

• Two novel approaches for simultaneous T1 and T2 mapping using balanced steady state free precession (bSSFP) acquisitions were developed.
• Method 1: Sequential T1 and T2 mapping modules.
• Method 2: Model-based joint T1/T2 approach (MR fingerprinting analog).

Main Results:

• Both developed methods demonstrated good agreement with literature values and comparative acquisitions.
• Simultaneous T1 and T2 maps were successfully acquired for multiple HP 13C compounds.
• Relaxation parameters were measured in the heart, liver, kidneys, and vasculature in a single acquisition.

Conclusions:

• The developed bSSFP-based methods enable efficient and simultaneous T1 and T2 mapping of HP 13C probes.
• This advancement allows for comprehensive in vivo metabolic characterization of multiple compounds across various organs.
• These techniques represent a significant step forward for quantitative HP 13C MRI applications.