Multi-Shot Multi-Echo xSPEN Technique for Portable Low-Field MRI Systems
Published in NMR in Biomedicine, 2026
Abstract Purpose To develop and evaluate a Multi-Shot Multi-Echo cross-term Spatiotemporal Encoding (MS-ME xSPEN) sequence for highly compact, portable low-field MRI systems, improving imaging performance while preserving robustness to severe field inhomogeneity.
Methods The MS-ME xSPEN sequence was implemented using segmented and interleaved multi-shot image-domain sampling strategies. Segmented MS-ME xSPEN was selected for further comparison with conventional single-shot xSPEN. Experiments were performed on a 110 mT portable MRI system with three gradient axes, with a constant-gradient environment emulated by continuously activating a single gradient axis. Phantom and in vivo human brain imaging were performed.
Results MS-ME xSPEN showed strong resilience to in-plane distortion caused by field inhomogeneity and achieved higher SNR than standard xSPEN. It also enabled a wider range of T2-weighted contrasts.
Conclusion MS-ME xSPEN is well suited to compact portable low-field MRI systems, providing improved SNR, flexible contrast options, and robust performance under severe field inhomogeneity.
Recommended citation: Qiu, Y., Lee, P. K., Dai, K., Chen, S., Yang, S., Wang, C., Bai, H., Dang, Z., & Zhang, Z. (2026). "Multi-Shot Multi-Echo xSPEN Technique for Portable Low-Field MRI Systems." NMR in Biomedicine. doi: 10.1002/nbm.70294
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