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

Engel, Maria ORCID: https://orcid.org/0000-0002-0143-1908, Kasper, Lars, Wilm, Bertram, Dietrich, Benjamin, Patzig, Franz, Vionnet, Laetitia and Pruessmann, Klaas P. 2022. Mono‐planar T‐Hex: Speed and flexibility for high‐resolution 3D imaging. Magnetic Resonance in Medicine 87 (1) , pp. 272-280. 10.1002/mrm.28979

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Abstract

The aim of this work is the reconciliation of high spatial and temporal resolution for MRI. For this purpose, a novel sampling strategy for 3D encoding is proposed, which provides flexible k-space segmentation along with uniform sampling density and benign filtering effects related to signal decay. Methods For time-critical MRI applications such as functional MRI (fMRI), 3D k-space is usually sampled by stacking together 2D trajectories such as echo planar imaging (EPI) or spiral readouts, where each shot covers one k-space plane. For very high temporal and medium to low spatial resolution, tilted hexagonal sampling (T-Hex) was recently proposed, which allows the acquisition of a larger k-space volume per excitation than can be covered with a planar readout. Here, T-Hex is described in a modified version where it instead acquires a smaller k-space volume per shot for use with medium temporal and high spatial resolution. Results Mono-planar T-Hex sampling provides flexibility in the choice of speed, signal-to-noise ratio (SNR), and contrast for rapid MRI acquisitions. For use with a conventional gradient system, it offers the greatest benefit in a regime of high in-plane resolution <1 mm. The sampling scheme is combined with spirals for high sampling speed as well as with more conventional EPI trajectories. Conclusion Mono-planar T-Hex sampling combines fast 3D encoding with SNR efficiency and favorable depiction characteristics regarding noise amplification and filtering effects from urn:x-wiley:07403194:media:mrm28979:mrm28979-math-0003 decay, thereby providing flexibility in the choice of imaging parameters. It is attractive both for high-resolution time series such as fMRI and for applications that require rapid anatomical imaging.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Psychology Cardiff University Brain Research Imaging Centre (CUBRIC)
Publisher:	Wiley
ISSN:	0740-3194
Date of First Compliant Deposit:	5 December 2022
Date of Acceptance:	31 July 2021
Last Modified:	07 May 2023 14:36
URI:	https://orca.cardiff.ac.uk/id/eprint/154623

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