³¹P MRSI Coil Combination Using ²³Na Sensitivity Information

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Spectroscopy
• Biophysics

Background:

• ³¹P MRSI is crucial for metabolic imaging but suffers from low signal-to-noise ratio (SNR).
• Optimal combination of multi-channel receiver data is essential for improving ³¹P MRSI quality.
• Traditional methods rely on low-SNR ³¹P data for sensitivity estimation, potentially introducing bias.

Purpose of the Study:

• To develop and validate a novel method for combining ³¹P MRSI receive channels.
• To leverage high-SNR ²³Na sensitivity maps for improved ³¹P MRSI signal combination.
• To overcome limitations of traditional self-weighting methods in low-SNR ³¹P MRSI.

Main Methods:

• Utilized a 15-channel X-nuclei head coil for simultaneous ²³Na and ³¹P imaging.
• Acquired low-SNR ³¹P MRSI and high-SNR ²³Na sensitivity data.
• Combined ³¹P MRSI signals using ²³Na sensitivity maps, validated via simulations, Monte Carlo studies, and in vivo experiments.

Main Results:

• Electromagnetic simulations showed <5% SNR loss with ²³Na sensitivities.
• ²³Na-based combination improved SNR in simulated and in vivo ³¹P spectra.
• The proposed method avoided the SNR overestimation bias inherent in self-weighting.

Conclusions:

• ³¹P MRSI channel combination using ²³Na sensitivities offers superior performance.
• This approach enhances SNR and reduces bias in low-SNR ³¹P MRSI.
• The method is effective when using the same receiver array for both nuclei.