MRI raw data to publication: Fuzzy ripple artifact in high resolution fMRI: identification, cause, and mitigation.

These Data are refering to the maunscript "Fuzzy ripple artifact in high resolution fMRI: identification, cause, and mitigation" authored by Renzo Huber1, Rüdiger Stirnberg2, A Tyler Morgan1, David A Feinberg3,4-5, Samantha J Ma6, Philipp Ehses3, Omer Faruk Gulban2,7, Kenshu Koiso2, Isabel Gephart1, Stephanie Swegle1, Susan Wardle1, Emily Ma2, Andrew Persichetti1, Alexander JS Beckett4-5, Tony Stöcker3, Nicolas Boulant8, Benedikt A Poser2, Peter Bandettini1 1 NIMH, NIH, Bethesda, United States, 2 German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany, 3 Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA, United States, 4 Advanced MRI Technologies, Sebastopol, CA, United States, 5 CN, FPN, University of Maastricht, The Netherlands, 6 Siemens Medical Solutions USA, Inc., Berkeley, CA, USA, 7 Brain Innovation, Maastricht, The Netherlands, 8 CEA, NeuroSpin, University Paris Saclay, France. Abstract Purpose: High resolution fMRI is an emerging research field focused on capturing functional signal changes across cortical layers. However, the data acquisition is limited by low spatial frequency EPI artifacts; termed as Fuzzy Ripples. These artifacts limit the practical applicability of acquisition protocols with higher spatial resolution, faster acquisition speed, and they challenge imaging in lower brain areas. Methods: We characterize Fuzzy Ripple artifacts across commonly used sequences and distinguish them from conventional EPI Nyquist ghosts, off-resonance effects, and GRAPPA artifacts. To investigate their origin, we employ dual polarity readouts. Results: Our findings indicate that Fuzzy Ripples are primarily caused by kx-specific imperfections in gradient trajectories, which can be exacerbated 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. Conclusion: The proposed mitigation strategies allow for overcoming current limitations in layer-fMRI protocols: (1) Achieving resolutions beyond 0.8mm is feasible, and even at 3T, we achieved 0.53mm voxel functional connectivity mapping. (2) Temporal acquisition speed can be increased to GRAPPA 8. (3) Sub-millimeter fMRI is achievable in lower brain areas, including the cerebellum.本数据集关联的研究论文为"高分辨率功能磁共振成像中的模糊波纹伪影：识别、成因与抑制"（Fuzzy ripple artifact in high resolution fMRI: identification, cause, and mitigation），作者如下：Renzo Huber¹, Rüdiger Stirnberg², A Tyler Morgan¹, David A Feinberg³,4–5, Samantha J Ma⁶, Philipp Ehses³, Omer Faruk Gulban²,7, Kenshu Koiso², Isabel Gephart¹, Stephanie Swegle¹, Susan Wardle¹, Emily Ma², Andrew Persichetti¹, Alexander JS Beckett4–5, Tony Stöcker³, Nicolas Boulant⁸, Benedikt A Poser², Peter Bandettini¹ ¹ 美国国立精神卫生研究所（NIMH），美国国立卫生研究院（NIH），贝塞斯达，美国 ² 德国神经退行性疾病研究中心（DZNE），波恩，德国 ³ 海伦·威尔斯神经科学研究所，加州大学伯克利分校，伯克利，加利福尼亚州，美国 4–5 先进磁共振成像技术公司，塞巴斯托波尔，加利福尼亚州，美国；马斯特里赫特大学CN、FPN，荷兰 ⁶ 西门子医疗解决方案美国公司，伯克利，加利福尼亚州，美国 7 脑创新公司，马斯特里赫特，荷兰 ⁸ 法国原子能和替代能源委员会（CEA）神经自旋研究所，巴黎萨克雷大学，法国 ## 摘要 ### 研究目的 高分辨率功能磁共振成像（fMRI）是新兴研究领域，旨在捕捉大脑皮层各层级的功能信号变化。然而，其数据采集过程受限于低空间频率回波平面成像（EPI）伪影——此类伪影被称为"模糊波纹"（Fuzzy Ripples）。这类伪影不仅限制了高空间分辨率、快采集速度成像方案的实际应用，还为脑深部区域的成像带来了挑战。 ### 研究方法 本研究对常用序列下的模糊波纹伪影进行了系统表征，并将其与常规EPI奈奎斯特伪影、共振偏移效应及广义自动校准部分并行采集（GRAPPA）伪影加以区分。为探究其起源，我们采用了双极性读出方案。 ### 研究结果 研究结果显示，模糊波纹伪影主要由梯度轨迹中沿kx方向的特定缺陷所导致，而三阶匀场线圈与读出梯度之间的感应耦合可能会加剧此类伪影。此外，本研究还发现，可通过对双极性EPI数据进行复数值平均，或断开三阶匀场线圈来实现该伪影的抑制。 ### 研究结论 本研究提出的伪影抑制策略可突破当前层状fMRI成像方案的局限： (1) 实现优于0.8mm的空间分辨率具备可行性，即便在3T磁场强度下，我们也完成了0.53mm体素的功能连接映射； (2) 扫描速度可提升至GRAPPA 8； (3) 包括小脑在内的脑深部区域均可实现亚毫米级功能磁共振成像。