Fully Compensated Dynamic Shim System for In Vivo MRI and MRS

描述（申请人提供）：功能MRI、弥散MRI、磁共振波谱和光谱成像在疾病和损伤的研究和诊断、指导手术治疗方面具有很大的潜力。所有这些方法都大大受益于高场强磁铁（3T及以上）增加的灵敏度，分辨率和对比度。然而，由于空气和组织之间的磁化率差异引起的磁场不均匀性（MFI）影响日益混杂，高磁场的优势尚未充分发挥出来。MFI导致MRI中的信号丢失和空间失真，以及mrs中的频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在临床应用中没有得到广泛应用的主要原因。目前的磁场均匀化方法（即闪烁）在小体积上工作得很好，但在更大的物体上却不够，比如整个人类的大脑。在过去的五年中，耶鲁大学的磁共振小组开发了动态垫片更新（DSU）技术，该技术可以大大改善扩展区域的磁场均匀性。动态垫片更新将全局三维问题划分为若干块，在这些块上可以获得足够的磁场均匀性。与多层MRI序列同步动态更新预先确定的切片垫片，确保所有切片的最佳均匀性。鉴于该技术的成熟，以及对改善磁场均匀性的需求不断增加，将DSU发展成为商业上可行的方法是第一阶段STTR提案的目标。由于之前的所有开发都是在耶鲁大学专用设备上进行的，因此迈向商业化的第一步是开发、建造和测试一个独立的DSU单元。一旦建立了独立DSU装置的可行性，将在未来的第二期STTR应用中走向商业化之路。由于MFI影响体内核磁共振的许多方面，DSU的成功实施将对MRI和MRS的几乎所有方面产生重大影响，因此可以标记为高度显著。

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.