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

美国大约有4100万人患有残疾。这些残疾给个人、家庭和整个社会带来了沉重的负担。能够诱导神经元恢复和康复的技术是国家卫生的关键优先事项。然而，中枢神经系统的恢复或康复尤其难以实现，因为人类神经元再生缓慢或根本不再生，而且很难通过血脑屏障输送有用的药物。与此同时，最近发展的脑外科技术，称为聚焦超声，具有理想的神经康复技术的许多特点，因为聚焦超声可以在特定的地方和时间诱导脑组织的变化，而不会伤害周围的组织，并且被认为可以安全地打开血脑屏障。由于无法无损地测量活体体内的超声压力场，这些技术的发展受到了阻碍。这使得很难控制在治疗过程中可能引起的超声波脑组织效应。该项目的目标是通过构建能够无损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。完成后，该设备将允许医生和研究人员测量和控制超声波场，从而在治疗过程中引起特定的超声波与大脑的相互作用。本提案将设计、制作原型并验证一种新型超声编码电磁铁，该电磁铁可以插入磁共振成像（MRI）扫描仪中，并将声波纵向位移场编码到活体的磁共振图像中。位移数据可以用来估计物体内部的压力和声速等声学参数。如果成功，这种电磁铁插入提供的新信息将增强正在进行和未来超声神经调节治疗研究的科学严谨性。该项目将在以下三个阶段进行：1)设计，2)原型，和3)验证。设计阶段将使用仿真软件根据设计标准评估两种电磁铁设计，如电磁铁在2厘米距离上的编码能力、施加在设备上的洛伦兹力以及运行过程中的加热。在原型阶段，设备将根据设计阶段预测的性能标准进行构建和评估。该设备对MRI图像质量的影响也将被评估。如果该设备符合既定的性能标准，那么，在项目的验证阶段，电磁铁将用于估计组织模拟凝胶物体中产生的声压场。在这三个阶段完成后，本项目将生产一种新型设备，可以无损地测量水基物体的声压场，并且可以很容易地应用于基于超声波的神经康复研究。该奖项反映了美国国家科学基金会的法定使命，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.