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。在过去的五年里，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。动态垫片更新将全局3D问题分成多个切片，在这些切片上可以实现足够的磁场均匀度。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。鉴于该技术的成熟，以及对改善磁场均匀度的日益增长的需求，该第一阶段STTR提案的目标是将DSU开发成一种商业上可行的方法。由于之前的所有开发都是在耶鲁大学专用设备上进行的，迈向商业化的第一步是开发、建造和测试独立的DSU单元。一旦确定了独立的DSU装置的可行性，将在未来的第二阶段STTR应用中走上商业化之路。由于MFI影响到活体核磁共振的许多方面，成功地实施DSU将对MRI和MRS的几乎所有方面产生重大影响，因此可以被贴上非常重要的标签。

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 five years, 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. Dynamic shim updating 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. Given the maturity of the technique, as well as the increasing demand for improved magnetic field homogeneity, it is the goal of this Phase I STTR proposal to develop DSU into a commercially viable method. As all of the previous developments were performed on Yale-specific equipment, the first step towards commercialization is the development, construction and testing of a stand-alone DSU unit. Once the feasibility of the stand- alone DSU unit has been established, the road towards commercialization will be traveled in a future Phase II STTR application. Since MFI affects many facets of in vivo NMR, the successful implementation of DSU will have major impacts on almost all aspects of MRI and MRS and can thus be labeled as highly significant.