Synopsis

This educational talk will introduce the audience to the fundamentals, properties, and applications of non-Cartesian k-space sampling. The fundamentals of non-Cartesian imaging include sampling principles, pulse sequence design, and image reconstruction methods. Practical considerations for implementing non-Cartesian pulse sequences include gradient waveform design, k-space trajectory estimation, and correction for non-idealities such as main field inhomogeneity. Incorporating non-Cartesian trajectories into pulse sequences such as balanced SSFP and spin-echo train sequences involves interesting challenges and presents opportunities for faster and better imaging. Non-Cartesian sampling of 3D k-space enables highly-accelerated volumetric imaging.

Overview of Presentation

There is an infinite number of k-space trajectories that can be used for MRI data sampling. Cartesian (rectilinear) trajectories are the most common trajectories, in part because of straightforward image reconstruction and robustness to hardware imperfections and magnetic field variations. Echo-planar imaging (EPI) can be thought of as type of Cartesian trajectory, and it is widely used for single-shot imaging. This talk will focus on non-Cartesian trajectories,starting with radial and spiral trajectories and moving on to some “wilder” trajectories. Often the goal of using non-Cartesian trajectories is rapid scanning, but these trajectories can also enable applications such as ultrashort echo time (UTE) and motion-robust imaging. The sampling density of non-Cartesian trajectories can be designed to support methods for under-sampled image reconstruction, such as compressed sensing, and this combination can enable very rapid imaging.

This talk will cover the fundamentals of non-Cartesian imaging, including sampling principles, pulse sequence design, and image reconstruction methods. Practical considerations for implementing non-Cartesian pulse sequences include gradient waveform design, k-space trajectory estimation, and correction for non-idealities such as main field inhomogeneity. Incorporating non-Cartesian trajectories into pulse sequences such as balanced SSFP and spin-echo train (RARE) sequences involves interesting challenges and presents opportunities for faster or better imaging. Non-Cartesian sampling of 3D k-space provides exciting opportunities for highly-accelerated volumetric imaging. In summary, this presentation will introduce the audience to the fundamentals of non-Cartesian sampling and the exciting opportunities for research and clinical translation with these trajectories.

Acknowledgements

No acknowledgement found.

References

No reference found.