Clinically constrained optimization of flexTPI acquisition parameters for the tissue sodium concentration bioscale

Area of Science:

• Magnetic Resonance Imaging
• Biophysics
• Medical Physics

Background:

• Sodium magnetic resonance imaging (MRI) signal experiences T(2)-blurring during spatial encoding, reducing image resolution.
• Conventional approaches prioritize minimizing readout duration to combat T(2)-blurring.
• Flexible twisted projection imaging (FTPI) with ultrashort echo time is effective for quantitative sodium MRI.

Purpose of the Study:

• To investigate the optimal acquisition parameters for maximizing spatial resolution in quantitative sodium FTPI within clinically practical time limits.
• To challenge the conventional wisdom of minimizing readout duration for maximal spatial resolution.

Main Methods:

• Simulations and experimental data were used to determine resolution-optimized acquisition parameters for FTPI.
• Quantitative sodium MRI was performed on the human brain at 9.4T and 3.0T.
• Acquisition parameters were optimized considering a limited total acquisition time (e.g., 10 minutes).

Main Results:

• Maximal spatial resolution in FTPI is not achieved by minimizing readout duration when total acquisition time is clinically constrained.
• Optimal parameters were identified for quantitative sodium FTPI of brain parenchyma and cerebrospinal fluid.
• The study discusses the impact of signal loss on sodium quantification bias and image signal-to-noise ratio.

Conclusions:

• For clinically relevant acquisition times, the shortest readout duration is not necessarily optimal for spatial resolution in sodium MRI.
• Resolution-optimized FTPI parameters are crucial for accurate quantitative sodium imaging in the brain.
• Understanding signal loss effects is important for reliable sodium quantification and SNR in MRI.