Mono-planar T-Hex: Speed and flexibility for high-resolution 3D imaging.

Area of Science:

• Medical Imaging
• Magnetic Resonance Imaging (MRI)
• Biomedical Engineering

Background:

• Current MRI techniques often compromise spatial or temporal resolution, particularly for time-critical applications like functional MRI (fMRI).
• Traditional 3D k-space sampling in MRI involves stacking 2D trajectories, limiting acquisition speed and resolution.
• Previous methods like tilted hexagonal (T-Hex) sampling offered solutions for high temporal and lower spatial resolution.

Purpose of the Study:

• To reconcile high spatial and temporal resolution in MRI through a novel 3D encoding sampling strategy.
• To introduce a modified mono-planar T-Hex sampling method for medium temporal and high spatial resolution MRI.
• To provide flexible k-space segmentation with uniform sampling density and reduced signal decay artifacts.

Main Methods:

• A modified mono-planar T-Hex sampling strategy was developed for 3D k-space acquisition.
• This approach acquires a smaller k-space volume per shot, optimizing for medium temporal and high spatial resolution.
• The sampling scheme was integrated with spiral and echo planar imaging (EPI) trajectories for enhanced speed.

Main Results:

• Mono-planar T-Hex sampling demonstrated flexibility in balancing speed, signal-to-noise ratio (SNR), and contrast for rapid MRI.
• The method is particularly beneficial for high in-plane resolution (<1 mm) with conventional gradient systems.
• Combined with spiral and EPI, it facilitates high sampling speeds and efficient 3D encoding.

Conclusions:

• Mono-planar T-Hex sampling offers a solution for achieving both fast 3D encoding and high SNR in MRI.
• It presents favorable depiction characteristics, mitigating noise amplification and signal decay effects.
• This technique is suitable for high-resolution time series (e.g., fMRI) and rapid anatomical imaging.