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arXiv · 1907.13261

Robust Autocalibrated Structured Low-Rank EPI Ghost Correction

Rodrigo A. Lobos·W. Scott Hoge·Ahsan Javed·Congyu Liao·Kawin Setsompop·Krishna S. Nayak·Justin P. Haldar
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Abstract

Purpose: We propose and evaluate a new structured low-rank method for EPI ghost correction called Robust Autocalibrated LORAKS (RAC-LORAKS). The method can be used to suppress EPI ghosts arising from the differences between different readout gradient polarities and/or the differences between different shots. It does not require conventional EPI navigator signals, and is robust to imperfect autocalibration data. Methods: Autocalibrated LORAKS is a previous structured low-rank method for EPI ghost correction that uses GRAPPA-type autocalibration data to enable high-quality ghost correction. This method works well when the autocalibration data is pristine, but performance degrades substantially when the autocalibration information is imperfect. RAC-LORAKS generalizes Autocalibrated LORAKS in two ways. First, it does not completely trust the information from autocalibration data, and instead considers the autocalibration and EPI data simultaneously when estimating low-rank matrix structure. And second, it uses complementary information from the autocalibration data to improve EPI reconstruction in a multi-contrast joint reconstruction framework. RAC-LORAKS is evaluated using simulations and in vivo data, including comparisons to state-of-the-art methods. Results: RAC-LORAKS is demonstrated to have good ghost elimination performance compared to state-of-the-art methods in several complicated EPI acquisition scenarios (including gradient-echo brain imaging, diffusion-encoded brain imaging, and cardiac imaging). Conclusion: RAC-LORAKS provides effective suppression of EPI ghosts and is robust to imperfect autocalibration data.

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Rodrigo A. Lobos, W. Scott Hoge, Ahsan Javed, Congyu Liao, Kawin Setsompop, Krishna S. Nayak, Justin P. Haldar. 2019-07-30. Robust Autocalibrated Structured Low-Rank EPI Ghost Correction. https://arxiv.org/abs/1907.13261

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