Abstract #1363

Field-Correcting GRAPPA (FCG): a generalizable technique to correct spatiotemporal varying odd-even phase errors in EPI, SMS-EPI and 3D-EPI

Nan Wang¹, Daniel Raz Abraham², Hua Wu³, Congyu Liao¹, Xiaozhi Cao¹, Jonathan Polimeni⁴, Renzo Huber⁵, Qiang Liu⁶, Lipeng Ning⁶, Yogesh Rathi⁶, Nastaren Abad⁷, Baolian Yang⁸, Adam Kerr⁹, Carl-Fredrik Westin⁶, and Kawin Setsompop¹

¹Radiology, Stanford University, Stanford, CA, United States, ²Electrical Engineering, Stanford University, Stanford, CA, United States, ³3. Cognitive and Neurobiological Imaging Center, Stanford University, Stanford, CA, United States, ⁴Radiology Department, Harvard Medical School, Charlestown, MA, United States, ⁵5. Functional Magnetic Resonance Facility (FMRIF), National Institutes of Health, Bethesda, MD, United States, ⁶Mass General Brigham, Harvard Medical School, Boston, MA, United States, ⁷GE HealthCare, Niskayuna, NY, United States, ⁸GE Healthcare,, Waukesha, WI, United States, ⁹Cognitive and Neurobiological Imaging Center, Stanford University, Stanford, CA, United States

Synopsis

Keywords: Artifacts, Artifacts, EPI ghost correction; eddy current

Motivation: Odd-even phase errors are a long-standing problem for EPI, especially in cases with strong gradient systems and high field strengths.

Goal(s): To enable high-quality odd-even correction in challenging cases using field-correcting GRAPPA (FCG).

Approach: the FCG technique was applied to in vivo studies for 1-mm 3D EPI (CAIPI undersampling R=4) at 7T system, and 2D EPI (SMS=1-4, R=2-4) at 3T high-performance system through a straightforward and flexible pipeline for separate ghost correction and image reconstruction.

Results: FCG produced the best correction and cleanest output on challenging cases. The pipeline is effective and flexible for different EPI structures and different vendors.

Impact: A field-correcting GRAPPA (FCG) technique for high-quality correction of odd-even phase errors in EPI and a flexible pipeline for separate data correction and reconstruction was developed and validated, unleashing EPI applications for higher undersampling, stronger gradient systems, and higher fields.

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