Multidimensional compressed sensing to advance ²³ Na multi-quantum coherences MRI

Area of Science:

• Medical Imaging
• Magnetic Resonance Imaging
• Biophysics

Background:

• Sodium (²³ Na) multi-quantum coherences (MQC) MRI is crucial for in vivo human brain imaging.
• Accelerating 3D MQC MRI acquisition is essential for clinical feasibility.
• Compressed sensing (CS) offers a promising approach for MRI acceleration.

Purpose of the Study:

• To accelerate 3D ²³ Na MQC MRI using a novel five-dimensional (5D) CS framework.
• To enable simultaneous Cartesian single (SQ) and triple quantum (TQ) sodium imaging.
• To evaluate the performance of 5D CS at 3.0 T and 7.0 T for in vivo human brain imaging.

Main Methods:

• Developed a 5D CS framework extending conventional 3D CS to exploit sparsity in all imaging dimensions.
• Acquired 3D ²³ Na MQC MRI data from simulated brain, phantom, and healthy volunteers at 3.0 T and 7.0 T.
• Retrospectively and prospectively undersampled data, analyzing performance using SSIM, RMSE, SNR, and sodium concentration quantification.

Main Results:

• Achieved three-fold acceleration with scan times under 5 minutes and high resolution at 3.0 T.
• 5D CS improved SSIM and reduced RMSE for in vivo SQ, TQ, and TQ/SQ ratio maps.
• Demonstrated unprecedented high-resolution MQC images of the in vivo human brain at 7.0 T via prospective undersampling without extending acquisition time.

Conclusions:

• 5D CS enables up to three-fold retrospective acceleration on 3.0 T data.
• Demonstrated two-fold prospective acceleration at 7.0 T, achieving higher spatial resolution for ²³ Na MQC MRI.