Partial Fourier techniques in single-shot cross-term spatiotemporal encoded MRI

TL;DR

This paper investigates partial Fourier transform techniques in single-shot xSPEN MRI to reduce SNR penalties and improve sensitivity, demonstrating practical benefits on preclinical and human scanners.

Contribution

It introduces novel partial Fourier methods tailored for xSPEN MRI, optimizing image quality and acquisition efficiency by exploiting the unique encoding scheme.

Findings

Partial Fourier xSPEN reduces acquisition time and enhances sensitivity.

Implementation along the xSPEN axis yields significant performance gains.

Methods are validated on preclinical and human MRI scanners.

Abstract

Purpose: Cross-term spatiotemporal encoding-xSPEN-is a single-shot imaging approach with exceptional resilience to field heterogeneities: its images do not require a priori information nor use post-acquisition corrections, to deliver faithfully the spatial distribution. xSPEN, however, suffers from SNR penalties due to its non-Fourier nature and due to diffusion losses- specially when desiring high resolution. This study explores partial Fourier transform approaches that acting along either the readout or the spatiotemporally-encoded dimensions, reduce these penalties. Methods: xSPEN uses an orthogonal gradient to read, in direct space, the lowbandwidth dimension. This changes substantially the nature of partial Fourier acquisitions vis-a-vis conventional imaging counterparts. A suitable theoretical analysis, however, allows one to implement these procedures along either the low-bandwidth or readout axes. Results: Partial Fourier single-shot xSPEN methods are illustrated on preclinical and human scanners. Owing to their reduction in the experimental acquisition times, these methods provide substantial sensitivity gains vis-a-vis previous implementations for a given targeted in-plane resolution. The magnitude of these gains is as expected. Conclusion: Partial Fourier approaches, particularly when implemented along the xSPEN axis, can provide substantial sensitivity advantages at minimal costs in the operation of the single-shot experiments.