Shang Yun, Simegn Gizeaddis Lamesgin, Gillen Kelly, Yang Hsin-Jung, Han Hui
Department of Radiology, Weill Medical College of Cornell University, New York, NY 10065, United States.
Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, United States.
Psychoradiology. 2024 Aug 14;4:kkae013. doi: 10.1093/psyrad/kkae013. eCollection 2024.
High magnetic field homogeneity is critical for magnetic resonance imaging (MRI), functional MRI, and magnetic resonance spectroscopy (MRS) applications. B inhomogeneity during MR scans is a long-standing problem resulting from magnet imperfections and site conditions, with the main issue being the inhomogeneity across the human body caused by differences in magnetic susceptibilities between tissues, resulting in signal loss, image distortion, and poor spectral resolution. Through a combination of passive and active shim techniques, as well as technological advances employing multi-coil techniques, optimal coil design, motion tracking, and real-time modifications, improved field homogeneity and image quality have been achieved in MRI/MRS. The integration of RF and shim coils brings a high shim efficiency due to the proximity of participants. This technique will potentially be applied to high-density RF coils with a high-density shim array for improved B homogeneity. Simultaneous shimming and image encoding can be achieved using multi-coil array, which also enables the development of novel encoding methods using advanced magnetic field control. Field monitoring enables the capture and real-time compensation for dynamic field perturbance beyond the static background inhomogeneity. These advancements have the potential to better use the scanner performance to enhance diagnostic capabilities and broaden applications of MRI/MRS in a variety of clinical and research settings. The purpose of this paper is to provide an overview of the latest advances in B magnetic field shimming and magnetic field control techniques as well as MR hardware, and to emphasize their significance and potential impact on improving the data quality of MRI/MRS.
高磁场均匀性对于磁共振成像（MRI）、功能磁共振成像和磁共振波谱（MRS）应用至关重要。磁共振扫描期间的磁场不均匀性是一个长期存在的问题，由磁体缺陷和场地条件导致，主要问题是组织间磁化率差异引起的人体磁场不均匀性，导致信号丢失、图像失真和光谱分辨率差。通过被动和主动匀场技术的结合，以及采用多线圈技术、优化线圈设计、运动跟踪和实时修改的技术进步，MRI/MRS中已实现了更高的场均匀性和图像质量。射频线圈和匀场线圈的集成由于参与者距离较近而带来了高匀场效率。该技术可能会应用于具有高密度匀场阵列的高密度射频线圈，以改善磁场均匀性。使用多线圈阵列可以实现同时匀场和图像编码，这也能够开发使用先进磁场控制的新型编码方法。场监测能够捕获并实时补偿静态背景不均匀性之外的动态场扰动。这些进展有可能更好地利用扫描仪性能，以增强诊断能力，并拓宽MRI/MRS在各种临床和研究环境中的应用。本文的目的是概述磁场匀场和磁场控制技术以及磁共振硬件的最新进展，并强调它们对提高MRI/MRS数据质量的重要性和潜在影响。
