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Trajectory analysis for field free line magnetic particle imaging
Can Barış Top1, Alper Güngör1, Serhat Ilbey1
1ASELSAN Research Center, 06370, Ankara, Turkey.
Medical Physics
|January 30, 2019
Summary
For magnetic particle imaging (MPI), the Uniform Spiral trajectory offers optimal image quality and speed for large fields of view. Advanced reconstruction methods like ADMM improve contrast and resolution, reducing trajectory density needs.
Area of Science:
- Medical Imaging
- Biophysics
- Nanotechnology
Background:
- Magnetic Particle Imaging (MPI) is an emerging medical imaging modality.
- MPI utilizes magnetic nanoparticle (MNP) tracers for high-resolution imaging.
- Field Free Line (FFL) scanning enhances sensitivity over Field Free Point (FFP) scanning.
Purpose of the Study:
- To analyze and compare image quality of various FFL trajectories for large field of view (FOV) MPI.
- To provide baseline data for designing FFL scanning MPI systems.
- To optimize imaging parameters considering scan time, hardware constraints, and patient safety.
Main Methods:
- Simulated a human-sized FFL scanning MPI system with a 160 mm diameter FOV.
- Compared Radial, Spiral, Uniform Spiral, Flower, and Lissajous trajectories at varying densities.
- Analyzed system matrices for coherence and sensitivity, and calculated induced electric fields for safety assessment.
- Utilized Algebraic Reconstruction Technique (ART) and Alternating Direction Method of Multipliers (ADMM) for image reconstruction.
Main Results:
- Radial and Spiral trajectories showed poor performance at low densities.
- Uniform Spiral trajectory achieved the highest image quality with ART at low densities.
- Uniform Spiral, Flower, and Lissajous trajectories performed comparably with ADMM reconstruction.
- ADMM generally yielded higher contrast and resolution than ART.
Conclusions:
- Uniform Spiral trajectory is recommended for large FOV MPI, balancing image quality, scan time, and safety.
- Radial trajectory may be suitable for smaller FOVs, especially with advanced reconstruction priors.
- ADMM reconstruction offers superior image quality, potentially reducing the need for high trajectory densities.
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