Gradient-Free Quantitative MRI using a Combination of B1-Selective Excitation and Fingerprinting

结合使用 B1 选择性激励和指纹识别的无梯度定量 MRI

• 批准号: 10390516
• 负责人: William A Grissom
• 金额: $ 65.35万
• 依托单位: CASE WESTERN RESERVE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-06-01 至 2026-02-28
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10390516
• 关键词: 3-Dimensional; Acceleration; Algorithms; Amplifiers; Brain; Brain imaging; Brain scan; Caliber; Clinical; Code; Complex; Custom; Data; Dictionary; Disease; Fingerprint; Generations; Head; Heating; Human; Image; Lesion; Loudness; MRI Scans; Machine Learning; Magnetic Resonance Imaging; Maintenance; Maps; Medical Imaging; Methods; Nuts; Output; Patients; Performance; Peripheral Nerve Stimulation; Peripheral Nerves; Phase; Physiologic pulse; Process; Property; RF coil; Reader; Renaissance; Resolution; Rotation; Safety; Scanning; Signal Transduction; Site; Speed; System; Time; Tissues; Training; Translating; Variant; base; contrast imaging; cost; cost effective; design; experience; experimental study; flexibility; human subject; imaging modality; imaging system; improved; in vivo; magnetic field; novel; operation; portability; quantitative imaging; radio frequency; radiologist; reconstruction; transmission process; wireless

Project Summary Magnetic Resonance Imaging (MRI) is one of the most important medical imaging modalities because of its ability to detect and characterize lesions throughout the body. However, access to MRI is severely limited by its expensive hardware, complex siting requirements and typically-qualitative images, which require highly skilled radiologists to interpret. This project proposes a fundamentally new way to encode MRI that could enable sub- stantially cheaper and more flexible quantitative MRI scanners. Today the overwhelming majority of MRI scans are encoded using two primary methods: B0 gradients and parallel imaging using an array of receiver coils. B0 gradients take up a significant fraction of the bore diam- eter; are loud and induce peripheral nerve stimulation, compromising patient comfort; they have relatively long switching times due to the high inductance of the coils; they require bulky cooling systems and customized am- plifiers; they are expensive, representing 25-30% of the cost of a clinical scanner; and they must be carefully designed and customized to a scanner's B0 magnet. B0 gradient encoding also suffers from spatial errors due to concomitant terms, which increase with decreasing B0 field strength and will limit the performance of emerging portable and low-cost MRI systems. Parallel imaging enables scan acceleration by differentiating signals across large spatial distances, but cannot encode complete images on its own. While some have proposed a third class of encoding methods using radiofrequency transmit (B1+) gradients, none of the methods described to date have been translated into clinical use because of practical limits on their performance, stringent hardware requirements and lack of flexibility in image contrast. This project will develop and validate a fourth, fundamentally new way to encode MRI based on parallel transmission using B1+-selective pulses produced by wireless RF coil units with on-coil amplifiers that perform RF transmission and reception, combined with an acquisition and reconstruction process inspired by MR Finger- printing (MRF). This new method, Selective Encoding through Nutation and Fingerprinting (SENF), completely eliminates the need for B0 gradients and is compatible with a wide range of magnet designs and flexible ac- quisition strategies. Unlike previous B1+ imaging methods, SENF places no strict spatial variation requirements on the RF gradient fields, which enables flexible system design, and the same coils can be used for spatial en- coding and signal reception. Furthermore, instead of suffering from errors due to complex spin dynamics during RF encoding, SENF leverages those dynamics to its advantage to differentiate quantitative tissue parameters. Successful completion of this project will enable a new generation of cheaper, more accessible, more modular, and lower-maintenance MRI scanners with quantitative outputs that can be more directly related to disease and tissue states.

项目概要 磁共振成像 (MRI) 是最重要的医学成像方式之一，因为它具有 然而，MRI 的使用受到其严重限制。 昂贵的硬件、复杂的坐姿要求和通常质量的图像，这些都需要高超的技术 该项目提出了一种全新的 MRI 编码方法，可以实现亚 更便宜、更灵活的定量 MRI 扫描仪。 如今，绝大多数 MRI 扫描都使用两种主要方法进行编码： B0 梯度 使用接收线圈阵列的并行成像 B0 梯度占据了孔径的很大一部分。 噪音较大，会刺激周围神经，影响患者的舒适度； 由于线圈的高电感而导致开关时间变长；它们需要庞大的冷却系统和定制的AM- 钳子很贵，占临床扫描仪成本的 25-30%，必须小心使用； 针对扫描仪的 B0 磁体设计和定制的 B0 梯度编码也会因空间误差而受到影响。 伴随项，随着 B0 场强的降低而增加，并将限制新兴的性能 便携式低成本 MRI 系统通过区分信号来加速扫描。 大的空间距离，但不能单独编码完整的图像，而有些人提出了第三类。 使用射频传输 (B1+) 梯度的编码方法中，迄今为止描述的方法都没有 由于其性能的实际限制和严格的硬件要求，已转化为临床使用 以及图像对比度缺乏灵活性。 该项目将开发并验证第四种全新的基于并行的 MRI 编码方法 使用由无线 RF 线圈单元产生的 B1+ 选择性脉冲进行传输，线圈上的放大器执行 RF 传输和接收，结合受 MR Finger 启发的采集和重建过程 这种新方法，通过章动和指纹进行选择性编码（SENF），完全 消除了对 B0 梯度的需要，并与各种磁铁设计和灵活的交流兼容 与之前的 B1+ 成像方法不同，SENF 没有严格的空间变化要求。 在射频梯度场上，这使得灵活的系统设计成为可能，并且相同的线圈可用于空间en- 此外，在编码和信号接收过程中，不会因复杂的自旋动力学而遭受错误。 RF 编码、SENF 利用这些动态优势来区分定量组织参数。 该项目的成功完成将使新一代更便宜、更容易使用、更模块化、 以及维护成本较低的 MRI 扫描仪，其定量输出可以更直接地与疾病和疾病相关 组织状态。