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Passive antennas for improved image quality in transcranial MR-guided focused ultrasound

用于提高经颅 MR 引导聚焦超声图像质量的无源天线

基本信息

批准号：
10394425
负责人：
Xinqiang Yan
金额：
$ 20.45万
依托单位：
VANDERBILT UNIVERSITY MEDICAL CENTER
依托单位国家：
美国
项目类别：
财政年份：
2020
资助国家：
美国
起止时间：
2020-05-01 至 2024-01-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10394425
关键词：
Ablation Acoustics Address Attenuated Back Bathing Behavior Blood - brain barrier anatomy Brain Cell Nucleus Clinical Coiled Bodies Couples Diffusion Diffusion Magnetic Resonance Imaging Electromagnetic Energy Electromagnetics Elements Ensure Essential Tremor FDA approved Female Focused Ultrasound Focused Ultrasound Therapy Future Gel Goals Head Heating Height Hot Spot Hypothalamic structure Image Knowledge Leg Length Lesion MRI Scans Magnetic Resonance Imaging Measurement Measures Mechanics Medicare Methods Modeling Monitor Movement Disorders Neurodegenerative Disorders Noise Outcome Parkinson Disease Patients Pattern Performance Phase Population Positioning Attribute Prevalence Procedures Recovery Running Safety Scalp structure Scanning Scientist Shapes Signal Transduction Sonication Structure Surface System Technology Temperature Therapeutic Agents Thermometry Thinness Time Tissues Transducers Travel Tremor Ultrasonic Transducer Vendor Water Work base career clinical application design experimental study healthy volunteer improved male minimally invasive neuroimaging neurosurgery novel painful neuropathy prevent prospective radio frequency real time monitoring simulation tractography treatment site ultrasound volunteer

项目摘要

Project Summary/Abstract Transcranial MR-guided focused ultrasound (tcMRgFUS) neurosurgery is a non-invasive treatment for essential tremor, neuropathic pain, and many emerging applications. tcMRgFUS systems have a water bath that couples acoustic energy into the head and is circulated to cool the scalp between sonications. The water bath, however, also acts as a high permittivity dielectric with a much shorter RF wavelength than free space. At the same time, the transducer bowl is electrically conductive, so when the electromagnetic waves generated by the MRI scanner for imaging enter the bath, they travel through the bath in the transducer bowl and reflect off the bowl’s inner surface above the head. The reflected waves then cancel with the incoming waves which causes a dark band with very low MR signal in the images, and generally low signal throughout the brain. The low signal limits the types of scans that can be used to guide and assess tcMRgFUS treatment, especially spin echo scans such as diffusion which could enable earlier lesion and tractography-based assessment. To address this problem, we propose to develop a novel passive reflecting antenna that will sit in the water bath above the head, and will create its own wave reflection that can be controlled so as to add constructively with the incoming wave, thereby restoring the MR signal to levels commensurate with imaging outside the transducer. The wires will require no electrical connections and can be made very thin to avoid disturbing the ultrasound beam. We also propose to develop a complementary ring of passive loop coils that would sit outside the bottom of the transducer and further increase the fields in the brain. We will use electromagnetic simulations of a tcMRgFUS system in an MRI scanner to optimize the antennas and loop coils, design mechanical holders for them that do not disturb the ultrasound beams and do not require modifying the transducer, and then evaluate them in MR imaging of healthy volunteers in a clinical tcMRgFUS system.

项目概要/摘要经颅 MR 引导聚焦超声 (tcMRgFUS) 神经外科手术是一种非侵入性治疗方法特发性震颤、神经性疼痛和许多新兴应用。 tcMRgFUS 系统配有水浴将声能耦合到头部并在超声处理之间循环以冷却头皮。水然而，浴还充当高介电常数电介质，其射频波长比自由空间短得多。在同时，换能器碗是导电的，因此当产生的电磁波用于成像的 MRI 扫描仪进入浴槽，它们穿过换能器碗中的浴槽并反射碗的内表面位于头部上方。然后反射波与入射波相抵消，造成图像中 MR 信号非常低的暗带，并且整个大脑的信号通常较低。这低信号限制了可用于指导和评估 tcMRgFUS 治疗的扫描类型，尤其是旋转回波扫描，例如扩散扫描，可以实现早期病变和基于纤维束成像的评估。到为了解决这个问题，我们建议开发一种新型无源反射天线，该天线将放置在水浴中在头顶上方，并将创建自己的波反射，可以控制该波反射，以便建设性地添加入射波，从而将 MR 信号恢复到与外部成像相称的水平传感器。这些电线不需要电气连接，并且可以做得很细，以避免干扰超声波束。我们还建议开发一个无源环路线圈的互补环，该环将位于传感器底部外部，进一步增加大脑中的磁场。我们将使用电磁在 MRI 扫描仪中模拟 tcMRgFUS 系统，以优化天线和环形线圈、设计机械支架不会干扰超声波束，并且不需要修改传感器，然后在临床 tcMRgFUS 系统中的健康志愿者的 MR 成像中对其进行评估。