Fully Compensated Dynamic Shim System for In Vivo MRI and MRS

描述(申请人提供)：功能磁共振成像、弥散磁共振成像和磁共振波谱成像在疾病和损伤的研究和诊断以及指导外科治疗方面具有巨大的潜力。所有这些方法都得益于高场强磁铁(3T及以上)增加的灵敏度、分辨率和对比度。然而，由于空气和组织的磁化率差异引起的磁场不均匀性(MFI)的混杂效应，强磁场的优势还没有完全实现。MFI在MRI中会导致信号丢失和空间失真，在MRS中会导致光谱分辨率和灵敏度的损失。这些伪影导致的可靠性损失是这些技术没有在临床上广泛应用的主要原因。目前的磁场均质化方法(即垫片)在小体积上效果很好，但对于较大的物体，如整个人脑，则不适用。在过去的十年里，耶鲁大学的MR小组开发了动态垫片更新(DSU)技术，该技术可以极大地改善扩展区域的磁场均匀度。该方法将全球三维问题分解为若干个切片，在这些切片上可以获得足够的磁场均匀度。与多切片MRI序列同步地动态更新预定切片垫片确保了所有切片的最佳同质性。在第一阶段STTR赠款成功完成之后，目前的第二阶段申请继续努力，以期实现DSU的商业化。具体地说，将进一步完善DSU硬件，并结合专业软件自动设置单元。由于DSU比常规垫片复杂得多，标准MR用户将为机组的日常操作提供额外的软件。由于MFI几乎影响到体内核磁共振的方方面面，因此，DSU的成功商业化将对MRI和MRS的临床应用产生重大影响，因此可以被贴上非常重要的标签。公共卫生相关性：磁共振成像(MRI)和光谱分析(MRS)是获得健康和疾病中完整人体组织的高质量图像和代谢概况的领先技术。不幸的是，样品引入的磁场强度的空间差异会严重降低MRI和MRS数据的质量，从而可能影响正常组织和病变组织的区分。目前的技术还不能完全消除空间磁场的变化。目前的项目重点是开发能够显著降低空间磁场变化的新技术，从而大大提高MRI和MRS的数据质量。

DESCRIPTION (provided by applicant): Functional MRI, diffusion MRI and MR spectroscopy and spectroscopic imaging have great potential for the study and diagnosis of disease and injury, and guiding surgical therapy. All of these methods benefit greatly from the added sensitivity, resolution and contrast from high field strength magnets (3T and above). However, the advantages of higher magnetic fields have not been fully realized due to the increasingly confounding effects of magnetic field inhomogeneity (MFI) caused by magnetic susceptibility differences between air and tissue. MFI leads to signal loss and spatial distortion in MRI and loss in spectral resolution and sensitivity in MRS. The loss of reliability due to these artifacts is a major reason why these techniques have not seen wide use in clinical applications. Current methods of magnetic field homogenization (i.e. shimming) work well on small volumes but are inadequate over larger objects, like the entire human brain. Over the last decade, the MR group at Yale University has developed the technique of dynamic shim updating (DSU) which allows greatly improved magnetic field homogeneity over extended regions. DSU divides a global 3D problem into a number of slices over which adequate magnetic field homogeneity can be achieved. Dynamically updating the pre-determined slice shims in sync with the multi-slice MRI sequence ensures optimal homogeneity for all slices. Following a successful completion of the Phase I STTR grant, the current Phase II application continues the work towards commercialization of DSU. Specifically, DSU hardware will be further improved and combined with professional software to automatically set up the unit. Since DSU is significantly more complicated than regular shimming, additional software will be provided for the every day operation of the unit by standard MR users. Since MFI affects almost all facets of in vivo NMR, the successful commercialization of DSU will have major impacts on the clinical application of MRI and MRS and can thus be labeled as highly significant. PUBLIC HEALTH RELEVANCE: Magnetic resonance imaging (MRI) and spectroscopy (MRS) are the leading techniques to obtain high-quality images and metabolic profiles of intact human tissues in health and disease. Unfortunately, spatial variations in magnetic field strength introduced by the sample can severely degrade the quality of MRI and MRS data, such that distinction of normal from diseased tissues may be compromised. Current technology is not able to completely cancel the spatial magnetic field variations. The current project focuses on the development of novel technology that can significantly reduce spatial magnetic field variations, thus leading to greatly increased MRI and MRS data quality.