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@ARTICLE{Huber:279036,
      author       = {Huber, Laurentius Renzo and Stirnberg, Rüdiger and Morgan,
                      A Tyler and Feinberg, David A and Ehses, Philipp and
                      Knudsen, Lasse and Gulban, Omer Faruk and Koiso, Kenshu and
                      Gephart, Isabel and Swegle, Stephanie and Wardle, Susan G
                      and Persichetti, Andrew S and Beckett, Alexander J S and
                      Stöcker, Tony and Boulant, Nicolas and Poser, Benedikt A
                      and Bandettini, Peter A},
      title        = {{S}hort-term gradient imperfections in high-resolution
                      {EPI} lead to {F}uzzy {R}ipple artifacts.},
      journal      = {Magnetic resonance in medicine},
      volume       = {94},
      number       = {2},
      issn         = {1522-2594},
      address      = {New York, NY [u.a.]},
      publisher    = {Wiley-Liss},
      reportid     = {DZNE-2025-00668},
      pages        = {571 - 587},
      year         = {2025},
      abstract     = {High-resolution fMRI is a rapidly growing research field
                      focused on capturing functional signal changes across
                      cortical layers. However, the data acquisition is limited by
                      low spatial frequency EPI artifacts; termed here as Fuzzy
                      Ripples. These artifacts limit the practical applicability
                      of acquisition protocols with higher spatial resolution,
                      faster acquisition speed, and they challenge imaging in
                      inferior regions of the brain.We characterize Fuzzy Ripple
                      artifacts across commonly used sequences and distinguish
                      them from conventional EPI Nyquist ghosts and off-resonance
                      effects. To investigate their origin, we employ
                      dual-polarity readouts.Our findings indicate that Fuzzy
                      Ripples are primarily caused by readout-specific
                      imperfections in k-space trajectories, which can be
                      exacerbated by short-term eddy current, and by inductive
                      coupling between third-order shims and readout gradients. We
                      also find that these artifacts can be mitigated through
                      complex-valued averaging of dual-polarity EPI or by
                      disconnecting the third-order shim coils.The proposed
                      mitigation strategies allow overcoming current limitations
                      in layer-fMRI protocols: Achieving resolutions beyond 0.8 mm
                      is feasible, and even at 3T, we achieved 0.53 mm voxel
                      functional connectivity mapping. Sub-millimeter sampling
                      acceleration can be increased to allow sub-second TRs and
                      laminar whole brain protocols with up to GRAPPA 8.
                      Sub-millimeter fMRI is achievable in lower brain areas,
                      including the cerebellum.},
      keywords     = {Artifacts / Humans / Brain: diagnostic imaging / Image
                      Processing, Computer-Assisted: methods / Algorithms /
                      Echo-Planar Imaging: methods / Brain Mapping: methods /
                      Phantoms, Imaging / Magnetic Resonance Imaging / 7 T
                      acquisition (Other) / Fuzzy Ripples (Other) / layer‐fMRI
                      (Other) / ventral brain (Other)},
      cin          = {AG Stöcker / AG Reuter},
      ddc          = {610},
      cid          = {I:(DE-2719)1013026 / I:(DE-2719)1040310},
      pnm          = {354 - Disease Prevention and Healthy Aging (POF4-354)},
      pid          = {G:(DE-HGF)POF4-354},
      typ          = {PUB:(DE-HGF)16},
      pubmed       = {pmid:40173320},
      doi          = {10.1002/mrm.30489},
      url          = {https://pub.dzne.de/record/279036},
}