Robust 3D MR spectroscopic imaging through multi-coil magnetic field shaping

项目摘要 磁共振波谱成像（MRSI）是一种功能强大的，非侵入性的方法来映射人体代谢轮廓 个脑袋MRSI的内在化学特异性可以揭示可能出现的区域的代谢改变， 在标准核磁共振成像上是非病理性的MRSI已成功用于脑肿瘤分类， 渗透，规划放射治疗和手术，并有助于表征一系列 神经退行性疾病，如多发性硬化症、阿尔茨海默病和癫痫。尽管它的优点 和成功，MRSI不是一种广泛的成像方式，因为该方法受到长期的阻碍， 磁场不均匀性的长期问题，这导致质量较低，因此重现性较差 数据不完全的水和脂质抑制可能会进一步损害数据质量。在过去十年中 我们已经开发了多线圈（MC）匀场，作为传统的基于球谐函数的 擦地通过控制通用圆形DC线圈矩阵中的电流， 在整个人脑中可以被改善到小于0.1 ppm。在此更新申请中，我们建议 运用我们丰富的MC磁场操作经验和MC匀场的上级性能， 在整个人脑中实现一致和可靠的MRSI性能。目标1的重点是 MC匀场的实现及其与超快速、基于EPI的MRSI的集成。MC技术将成为 修改和扩展以产生局部破碎梯度，从而有效抑制脂质。Aim 2关注 在人类大脑上验证MC增强的MRSI。除了MC和 目标2的常规匀场MRSI还将建立受试者内和受试者间以及重测 再现性此外，在4 T优化的MC设置将转移到3 T和7 T， 修改，以证明基于MC的匀场与临床MR系统的兼容性。的 当>90%的MRSI体素在 所有切片、所有受试者和所有扫描仪均符合严格的数据质量要求。虽然所有神经系统 疾病和病理可以受益于高保真MRSI，目标3侧重于获得高质量，可靠的 肿瘤患者的MRSI。在许多术后肿瘤患者中存在金属植入物， 肿瘤相关的病理，损害磁场均匀性。MC匀场将用于 证明高保真MRSI可以在具有挑战性的临床受试者人群中实现。

PROJECT SUMMARY MR spectroscopic imaging (MRSI) is a powerful, non-invasive method to map the metabolic profile of human brain. The intrinsic chemical specificity of MRSI can reveal altered metabolism in regions that would appear non-pathologic on standard MRI. MRSI has successfully been used for brain tumor classification and infiltration, planning of radiation therapy and surgery and has helped to characterize a range of neurodegenerative diseases such as multiple sclerosis, Alzheimer's disease and epilepsy. Despite its merits and successes, MRSI is not a widespread imaging modality because the method is hampered by the long- standing problem of magnetic field inhomogeneity, which leads to lower-quality and thus less-reproducible data. Incomplete water and lipid suppression can compromise data quality even further. Over the last decade we have developed multi-coil (MC) shimming as an alternative to conventional spherical harmonics based shimming. By controlling the current in a matrix of generic, circular DC coils the magnetic field homogeneity can be improved to less than 0.1 ppm across the entire human brain. In this renewal application we propose to apply our extensive experience with MC field manipulation and the superior performance of MC shimming to achieve consistent and reliable MRSI performance across the human brain. Aim 1 is focused on the implementation of MC shimming and its integration with ultra-fast, EPI-based MRSI. The MC technology will be modified and extended to generate local crusher gradients for effective lipid suppression. Aim 2 is concerned with the validation of MC-augmented MRSI on the human brain. Besides comparisons between MC and conventional shimmed MRSI, Aim 2 will also establish intra- and inter-subject, as well as test-retest reproducibility. In addition, the MC setup optimized at 4 T will be transferred to 3 T and 7 T, without modifications, to demonstrate compatibility of MC-based shimming with clinical MR systems. The implementation and validation of MC-augmented MRSI is considered complete when >90% of MRSI voxels on all slices, all subjects and all scanners adhere to stringent data quality requirements. While all neurological disorders and pathologies can benefit from high-fidelity MRSI, Aim 3 focuses on obtaining high-quality, reliable MRSI on tumor patients. The presence of metallic implants in many post-surgery tumor patients, in addition to tumor-related pathology, compromises the magnetic field homogeneity. MC shimming will be used to demonstrate that high-fidelity MRSI can be achieved on a challenging, clinical subject population.