Laterally Oscillating Trajectory for Undersampling Slices: LOTUS
Mayuri Sothynathan1,2, Paul I Dubovan3,4, Corey A Baron1,5
1Centre for Functional and Metabolic Mapping (CFMM), Robarts Research Institute, Western University, London, Ontario, Canada.
Magnetic Resonance in Medicine
|June 10, 2026
Summary
A new diffusion MRI technique, Laterally Oscillating Trajectory for Undersampling Slices (LOTUS), improves image quality and reduces scan time by enabling faster simultaneous multislice imaging. This method minimizes g-factor for better diffusion MRI data acquisition.
Area of Science:
- Medical Imaging
- Magnetic Resonance Imaging (MRI)
- Diffusion MRI
Background:
- Spiral sampling in diffusion MRI offers signal-to-noise ratio (SNR) benefits.
- Simultaneous multislice (SMS) acceleration in diffusion MRI is crucial for reducing scan times.
- Exploration of SMS acceleration with spiral trajectories remains limited.
Purpose of the Study:
- Introduce Laterally Oscillating Trajectory for Undersampling Slices (LOTUS), a novel 3D spiral-like k-space trajectory.
- Minimize g-factor through controlled incoherent aliasing for improved image reconstruction.
- Develop a constrained reconstruction approach for robust g-factor estimation in non-Cartesian reconstructions.
Main Methods:
- Simulated data acquisition using LOTUS and other trajectories on a numerical phantom.
- In vivo diffusion-weighted brain MRI acquisition in two subjects with varying acceleration factors (in-plane and slice).
- Quantitative and qualitative comparison of trajectory performance using g-factor maps and fractional anisotropy (FA) maps, with and without compressed sensing.
Main Results:
- Simulations demonstrated reduced g-factor (20%-31%) and improved reconstruction accuracy with LOTUS compared to other trajectories.
- In vivo acquisitions showed g-factor benefits and qualitative image quality improvements consistent with simulations.
- LOTUS performance improvements increased with higher numbers of simultaneous slices in both simulations and in vivo data.
Conclusions:
- LOTUS enables higher rates of slice acceleration in diffusion MRI.
- This acceleration capability has the potential to significantly decrease overall scan time.
- The findings highlight LOTUS as a promising technique for efficient diffusion MRI acquisition.
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