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Abstract #3480

Universal B0 shimming for whole-brain MRI at 7T

Matthijs H.S. de Buck1,2,3, Nikos Priovoulos1,4,5, and Wietske van der Zwaag1,2
1Spinoza Centre for Neuroimaging, Netherlands Institute for Neuroscience, Royal Netherlands Academy for Arts and Sciences, Amsterdam, Netherlands, 2Computational Cognitive Neuroscience and Neuroimaging, Netherlands Institute for Neuroscience, Royal Netherlands Academy for Arts and Sciences, Amsterdam, Netherlands, 3Department of Radiology and Nuclear Medicine, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, Netherlands, 4Department of Biomedical Engineering and Physics, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, Netherlands, 5Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom

Synopsis

Keywords: Shims, Bioeffects & Magnetic Fields, Brain, B0, Fields

Motivation: B0 shimming is essential for reducing field inhomogeneities in 7T brain MRI. However, the process is time-consuming and prone to inaccuracies due to large initial inhomogeneities or data processing errors.

Goal(s): To propose a universal B0 shim which provides an improved initial guess for iterative shimming algorithms, a time-efficient option for fast acquisitions, and a backup option.

Approach: A universal shim was calculated as the median of subject-specific shim coefficients. Shim performance was validated using B0 and EPI data.

Results: Compared to default settings, the universal B0 shim reduces average B0 inhomogeneity by 78Hz, only 3Hz less than subject-specific shims.

Impact: We propose an easy-to-use universal B0 shim for 7T brain MRI with similar performance to subject-specific shims. This can provide an improved initial estimate for iterative shimming, a time-efficient solution for ultrafast protocols, or a backup when subject-specific shimming fails.

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