Two-dimensional radial acquisition technique with density adaption in sodium MRI

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Medical Imaging Physics

Background:

• Conventional 2D radial projections in MRI exhibit suboptimal signal-to-noise ratio (SNR) efficiency due to non-uniform k-space sampling.
• This inefficiency can lead to image artifacts and reduced diagnostic accuracy, particularly in applications requiring high SNR.

Purpose of the Study:

• To develop and evaluate a novel 2D projection reconstruction method using variable gradient amplitudes for uniform k-space coverage.
• To enhance SNR efficiency and reduce artifacts in MRI by adapting sampling density.

Main Methods:

• A density-adapted 2D radial trajectory was designed with variable gradient amplitudes to maintain constant average sampling density.
• The performance of this new trajectory was compared against conventional 2D radial projection reconstruction methods.
• Implementation was assessed for ease of integration into existing MRI scanners, considering slew rate requirements.

Main Results:

• The density-adapted 2D radial trajectory achieved a higher signal-to-noise ratio, with up to a 28% increase observed in brain tissue.
• This technique demonstrated reduced image blurring and fewer artifacts, especially under magnetic field inhomogeneities.
• The method maintained the linear form of the radial trajectory while improving sampling uniformity.

Conclusions:

• The density-adapted 2D radial trajectory offers significant improvements in SNR and image quality over conventional methods.
• Its simple design and low hardware demands facilitate straightforward implementation on MRI scanners.
• The technique is highly suitable for specific applications like electrocardiographically gated sodium heart MRI and imaging of tissues with short relaxation times.