Wilson James L, Jenkinson Mark, Jezzard Peter
Centre for Functional Magnetic Resonance Imaging of the Brain, Department of Clinical Neurology, University of Oxford, John Radcliffe Hospital, Oxford, UK.
Magn Reson Med. 2002 Nov;48(5):906-14. doi: 10.1002/mrm.10298.
These preliminary studies demonstrate that static field inhomogeneity in the human inferior frontal cortex (IFC) is significantly diminished through placement of a small amount of strongly diamagnetic material in the roof of the mouth. As a result, susceptibility-related image artifacts in this region, as observed in blood oxygen level dependent (BOLD) functional MRI (fMRI), are considerably decreased without compromising the spatial or temporal resolution of the study. Simulations of the static field utilizing perturbation theory are shown, which support the experimental results. The limitations and possible future developments of the technique are described. The application of diamagnetic passive shimming on other regions of the brain is also discussed. Routine use of the proposed method within fMRI studies is practicable through subject-specific optimization of the technique utilizing the simulation algorithm.
这些初步研究表明，通过在口腔顶部放置少量强抗磁性材料，人类额下回（IFC）中的静磁场不均匀性显著降低。因此，在血氧水平依赖（BOLD）功能磁共振成像（fMRI）中观察到的该区域与磁化率相关的图像伪影大幅减少，同时不影响研究的空间或时间分辨率。展示了利用微扰理论对静磁场的模拟，其支持了实验结果。描述了该技术的局限性和可能的未来发展。还讨论了抗磁性被动匀场在大脑其他区域的应用。通过利用模拟算法对该技术进行特定受试者优化，在fMRI研究中常规使用所提出的方法是可行的。
