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、他们的家庭和整个社会带来了巨大的负担。能够诱导神经元恢复和康复的技术是关键的国家卫生优先事项。然而，中枢神经系统的恢复或康复尤其困难，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。同时，最近发展起来的被称为聚焦超声的脑外科技术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地点和时间诱导脑组织的变化，而不会损害周围组织，并且被认为可以安全地打开血脑屏障。由于无法非破坏性地测量活体内的超声压力场，这些技术的发展缓慢。这使得很难控制在治疗过程中可能会引发哪种超声波-脑组织效应。该项目的目标是通过建立能够无损测量活体受试者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。建成后，该设备将允许医生和研究人员测量和控制超声场，从而测量和控制治疗过程中诱导的特定超声波-脑相互作用。这项提议将设计、制作和验证一种新型的超声波编码电磁铁，它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受试者的磁共振图像中。然后，可以使用位移数据来估计声学参数，如对象内部的压力和声速。如果成功，这种电磁铁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疗法研究的科学严谨性。该项目将分以下三个阶段进行：1)设计、2)原型和3)验证。设计阶段将使用模拟软件根据设计标准对两个电磁铁设计进行评估，这些标准包括电磁铁在2厘米距离处的编码能力、施加在设备上的洛伦兹力以及运行期间的加热。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。还将评估该设备对MRI图像质量的影响。如果该设备满足既定的性能标准，则在项目的验证阶段，将使用电磁铁来估计在模拟组织的凝胶对象中诱导的声压场。在这三个阶段完成后，该项目将生产一种新的设备，可以无损地测量水中物体的声压场，并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NSF的法定使命，并通过使用基金会的智力优势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.