3rd order shim for high resolution fMRI at 7T: It hurts more than it helps
Motivation: 3rd order B0-shimming at high resolution 7T fMRI can mitigate geometric distortions. But the corresponding shim coils can induce field perturbations when mechanical resonances are excited (Boulant 2024). Goal(s): We aim to investigate the advantages and disadvantages of 3rd order shimming on high resolution fMRI across scanners and sequences. Approach: We compared EPI artifacts (Fuzzy Ripples) and geometric distortions with and without 3rd order shims in N=15 scans. Results: We find that for high-resolution fMRI protocols, it is best to conduct experiments without 3rd order shims. Shims should be physically disconnected. Impact: The results presented here inform the UHF-fMRI community about a simple trick to improve the data quality: disconnecting 3rd order shim coils.
Authors
- Rüdiger Stirnberg (ORCID: https://orcid.org/0000-0001-7021-1063)
- Peter A. Bandettini (ORCID: https://orcid.org/0000-0001-9038-4746)
- Nicolas Boulant (ORCID: https://orcid.org/0000-0003-2144-2484)
- Andrew Morgan (ORCID: https://orcid.org/0000-0001-6017-2179)
- Joelle E. Sarlls (ORCID: https://orcid.org/0000-0002-4734-5351)
- Laurentius Huber (ORCID: https://orcid.org/0000-0002-3291-2202)
- Yuhui Chai (ORCID: https://orcid.org/0000-0003-1523-3117)
- Benedikt Andreas Poser (ORCID: https://orcid.org/0000-0001-8190-4367)
- Federico De Martino (ORCID: https://orcid.org/0000-0002-0352-0648)
- Govind Bhagavatheeshwaran
Publication Details
- Journal
- Proceedings on CD-ROM - International Society for Magnetic Resonance in Medicine. Scientific Meeting and Exhibition/Proceedings of the International Society for Magnetic Resonance in Medicine, Scientific Meeting and Exhibition
- Published
- 2025-09-16
- DOI
- https://doi.org/10.58530/2025/0287
- Primary Topic
- Advanced MRI Techniques and Applications
- Type
- article
- Field-Weighted Citation Impact
- 0.00