Improved Diagnostic MRI around Metallic Implants

项目摘要 该项目将开发用于紧邻骨科的高分辨率软组织MRI的新技术 金属植入物，这是目前成像技术“看不见”的区域。我们将利用一个新的高度- 性能0.55特斯拉MRI平台，并将开发针对该平台优化的新软件和工具 和应用最后，我们在两个患者队列中评估了新的金属MRI技术， 立即影响患者管理：髋关节置换和脊柱固定。依据：Orthopedium金属 植入物广泛用于治疗晚期骨关节炎（全关节置换）、退行性椎间盘 疾病（脊柱固定）和创伤或骨切除后的骨折稳定。这些植入物无法 10%-40%的病例，使用软组织造影剂进行准确的非侵入性成像对于评估 硬件故障的根本原因，以及手术决策和计划。目前有一 对紧邻金属表面的高质量软组织成像的主要未满足需求， 例如，不利的局部组织反应或神经根撞击。最先进的多光谱成像（MSI） 导致了重大的改进~10年前，和技术已经平稳。创新：我们利用一种新颖的 0.55T MRI系统即将上市，仅这一项就有望减少图像伪影， 因为它提供了相对于磁致伸缩性引起的梯度和场强得多的成像梯度 移位、更高带宽的RF脉冲、均匀的RF传输，以及改进编码和 重建我们还提出了重新设想的MSI脉冲序列，以提供进一步的改善信号- 噪声比、编码时间和伪影。方法：我们的具体目标是：1）适应标准金属MSI 0.55T MRI平台的方法主要评估0.55T系统单独的改进， 减少非共振; 2）重新设计改进的金属MSI方法，利用梯度到B 0和RF 0.55T MRI平台的性能，以补偿SNR效率损失，同时提高空间分辨率 伪影抑制和提供脂肪/水分离; 3）比较0.55T MRI和3 T MRI方案 在植入髋关节和脊柱植入物的患者中，评估单独使用该系统和 重新设计MSI序列。更广泛的影响：该项目旨在展示改进的成像能力 比传统的1.5T和3 T场强更接近植入物表面， 髋关节置换术和脊柱固定术的术后评价背景。这将广泛有利于使用 金属患者的MRI，包括骨科和非骨科植入物。

PROJECT SUMMARY This project will develop new technology for high-resolution soft-tissue MRI immediately adjacent to orthopaedic metallic implants, an area that is “invisible” to current imaging techniques. We will leverage a novel high- performance 0.55 Tesla MRI platform and will develop new software and tools that are optimized for this platform and application. Finally, we evaluate the new metal MRI technology in two patient cohorts where it can immediately impact patient management: hip replacement and spinal fixation. Rationale: Orthopaedic metal implants are used extensively to treat late-stage osteoarthritis (total joint replacements), degenerative disc disease (spinal fixations), and fracture stabilization following trauma or bone resection. These implants fail in 10%-40% of cases, and accurate non-invasive imaging with soft-tissue contrast is essential for the evaluation of the underlying cause of hardware failure, and in surgical decision making and planning. At present, there is a major unmet need for high quality soft tissue imaging immediately adjacent to the metal surface to assess, for example, adverse local tissue response or nerve root impingement. State-of-the-art multi-spectral imaging (MSI) led to major improvements ~10 years ago, and the technology has plateaued. Innovation: We leverage a novel 0.55T MRI system that will soon be commercially available, which alone promises reduced image artifacts, because it provides much stronger imaging gradients relative to the susceptibility-induced gradients and field shifts, higher-bandwidth RF pulses, uniform RF transmission, and new opportunities for improved encoding and reconstruction. We also propose reimagined MSI pulse sequences to offer further improvements in signal-to- noise ratio, encoding time, and artifact. Approach: Our specific aims are: 1) to adapt standard metal MSI approaches for the 0.55T MRI platform to primarily assess the improvement of the 0.55T system alone due to reduced off-resonance; 2) to redesign improved metal MSI approaches that leverage the gradient-to-B0 and RF performance of the 0.55T MRI platform to compensate for lost SNR efficiency, while improving spatial resolution and artifact suppression and offering fat/water separation; and 3) to compare 0.55T MRI and 3T MRI protocols in patients with hip and spine implants, both to assess the improvement from the system alone and from redesigned MSI sequences. Broader Impact: This project aims to demonstrate improved capability to image closer to implant surfaces than what is possible at conventional 1.5T and 3T field strengths, and the impact in the context of post-surgical evaluation of hip-replacements and spinal fixations. This will broadly benefit the use of MRI in patients with metal, including orthopedic and non-orthopedic implants.