ERI: Magnetic Resonance Imaging of Acoustic Fields for Ultrasound-Based CNS Regeneration

在美国，大约有4100万人患有残疾。这些残疾给个人、其家庭和整个社会带来了巨大负担。能够诱导神经元恢复和康复的技术是国家健康的一个重要优先事项。然而，中枢神经系统的恢复或康复特别难以实现，因为人类神经元再生缓慢或根本不再生，并且难以通过血脑屏障递送有用的药物。与此同时，最近开发的脑外科技术，称为聚焦超声，具有理想的神经康复技术的许多特征，因为聚焦超声可以在特定的位置和时间诱导脑组织的变化，而不会伤害周围组织，并且被认为可以安全地打开血脑屏障。这些技术的发展由于不能非破坏性地测量活体内的超声压力场而减慢。这使得很难控制在治疗过程中可能引起的超声脑组织效应。该项目的目标是通过构建能够非破坏性地测量活体超声压力场的设备来加速基于超声的神经康复技术的发展。该设备完成后，医生和研究人员将能够测量和控制超声波场，从而在治疗过程中诱导特定的超声波-大脑相互作用。该提案将设计，原型和验证一种新型的超声波编码电磁体，可以插入磁共振成像（MRI）扫描仪，并将声学纵向位移场编码到活体对象的MR图像中。然后，位移数据可以用于估计声学参数，例如对象内部的压力和声速。如果成功，这种电磁体插入物提供的新信息将提高正在进行的和未来的超声神经调节治疗研究的科学严谨性。该项目将分以下三个阶段进行：1）设计，2）原型，3）验证。设计阶段将使用模拟软件根据设计标准（例如电磁体在2 cm距离处的编码能力、施加在器械上的洛伦兹力和操作期间的发热）评价两种电磁体设计。在原型阶段，将根据设计阶段预测的性能标准构建和评价器械。还将评估器械对MRI图像质量的影响。如果器械符合既定的性能标准，则在项目的确认阶段，电磁体将用于估计在仿组织凝胶物体中诱导的声压场。这三个阶段完成后，该项目将生产一种新型设备，可以非破坏性地测量水基物体中的声压场，并可以随时应用于基于超声的神经康复研究。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Approximately 41 million people within the United States suffer disability. These disabilities place a large burden on individuals, their families, and society as a whole. Technologies that can induce neuron restoration and rehabilitation are a critical national health priority. However, restoration or rehabilitation in the central nervous system is particularly hard to accomplish because human neurons regenerate slowly or not at all and it is difficult to deliver helpful drugs through the blood brain barrier. Meanwhile, recently developing brain surgical technologies, called focused ultrasound, possess many characteristics of an ideal neural rehabilitation technology because focused ultrasound can induce changes in brain tissue at specific places and times without harming surrounding tissues and are thought to safely open the blood-brain barrier. Development of these technologies is slowed by the inability to non-destructively measure the ultrasound pressure field inside a living subject. This makes it hard to control which ultrasound-brain tissue effect one might induce during therapy. The goal of this project is to accelerate the development of ultrasound-based neural rehabilitation technology by building devices that can non-destructively measure ultrasound pressure fields in living subjects. When completed, the device will allow doctors and researchers to measure and control the ultrasound field and, thereby, the specific ultrasound-brain interaction induced during therapy.This proposal will design, prototype, and validate a novel ultrasound-encoding electromagnet that can be inserted into a magnetic resonance imaging (MRI) scanner and encode acoustic longitudinal displacement fields into MR images of living subjects. The displacement data can then be used to estimate acoustic parameters such as pressure and sound speed inside the subject. If successful, the new information provided by this electromagnet insert will enhance the scientific rigor of ongoing and future ultrasound neuromodulation therapy studies. The project will be conducted in the following three phases: 1) design, 2) prototype, and 3) validation. The design phase will use simulation software to evaluate two electromagnet designs against design criteria such as the encoding capability of the electromagnet at 2 cm distance, Lorentz forces exerted on the device, and heating during operation. During the prototyping phase, the device will be constructed and evaluated against the performance criteria predicted during the design phase. The effects of the device on MRI image quality will also be assessed. If the device meets established performance criteria, then, during the validation phase of the project, the electromagnet will be used to estimate acoustic pressure fields induced in a tissue-mimicking gel object. Upon completion of these three phases, this project will produce a novel device that can non-destructively measure acoustic pressure fields in water-based objects and can be readily applied to ultrasound-based nerve rehabilitation studies.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.