High-Field MR-Compatible Dense Array EEG using Polymer Thick Film Technology

描述（由申请人提供）：拟议项目的长期目标是设计一种低剖面、高电阻、MRI兼容的密集阵列EEG传感器网络，用于在高达7特斯拉的磁场中同时进行dEEG/fMRI记录。这种新型的传感器网络（256通道InkNet）将使用创新的导电墨水引线，印刷在聚合物厚膜（PTF）上，由A。A.马萨诸塞州总医院马蒂诺中心。InkNet将与Electrical Geodesics Inc.最近开发的dEEG MRI兼容硬件和软件连接。（EGI）。该系统将为临床医生和研究人员提供安全，无创和负担得起的dEEG/fMRI技术，从而实现具有前所未有的时空分辨率的人类大脑功能的常规多模态成像。这项技术的应用将增强对健康大脑功能的理解，许多神经病变的治疗，{和术前计划}。对于第一阶段，第一个具体目标是修改EEG电极，用于MR兼容的密集阵列InkNet记录。新的InkNet将利用EGI的专利低轮廓256通道测地线传感器网络（HCGSN）结构。将开发和测试两种电极设计。第一个将通过将电极直接嵌入线束设计而不是使用粘合剂来将现有的32通道InkCap半环电极封装为适合HCGSN结构。替代设计将通过将EGI的颗粒电极粘合到印刷有聚酰亚胺导电胶的接口垫上，将其连接到PTF墨水引线。两种设计都将使用两种无磨损皮肤应用进行测试：EGI目前的电解质浸泡海绵和一种新型生物电位水凝胶。高信噪比（SNR）和低漂移的性能测试将确定第一阶段原型的最佳电极设计。第二个具体目标是设计新的PTF迹线，用于256根电极导线的有效布线。自动布线程序（SPECCTRA）将测试九个布线参数，以收敛于最佳走线宽度和长度，然后用于确定所需的过孔和层数。通过在SPECCTRA布线迭代期间测试间距违规，将实现5 mils的固定走线宽度，以确保可制造性。最终的原型电路将使用定制的碳和银油墨混合印刷，并测试其最佳介电和导电性能。第三个具体目标是测试新的dEEG/fMRI系统的安全性和数据完整性。将使用具有解剖学准确头部模型的时域有限差分（FDTD）数值模拟进行安全性测试，然后使用专门开发的体模（CHEMA）、高功率TSE成像序列（以诱导RF发热）和四通道荧光温度计在7 T扫描仪中进行实际温度测量。在确认安全性后，将使用T1加权结构序列、静息EEG α方案和视觉处理研究在3 T和7 T场强下测试MRI和EEG数据完整性。分析将对比使用和不使用InkNet的MRI质量，以及MR扫描仪内外的EEG质量。 公共卫生相关性：该项目的目标是开发一个系统，使用两种互补的方法同时测量大脑活动：脑电图（EEG）和功能磁共振成像（fMRI）。这一最先进的系统将为脑科学家和临床医生提供一种安全、非侵入性的工具，以前所未有的空间和时间精度研究人类大脑功能。这些知识将帮助我们更好地了解健康的大脑功能，治疗许多疾病（例如，癫痫），并改善术前计划。

DESCRIPTION (provided by applicant): The long-term objective of the proposed project is to design a low-profile, high-resistive, MRI-compatible dense array EEG sensor net for simultaneous dEEG/fMRI recordings in fields as high as 7 Tesla. This novel sensor net (256-channel InkNet) will use innovative conductive ink leads printed on polymer thick film (PTF) developed at the Analog Brain Imaging Laboratory (ABILAB) at the A. A. Martinos Center of Massachusetts General Hospital. The InkNet will interface with dEEG MRI-compatible hardware and software recently developed at Electrical Geodesics Inc. (EGI). This proposed system will provide safe, noninvasive, and affordable dEEG/fMRI technology to both clinicians and researchers, thereby enabling routine multimodal imaging of human brain function with unprecedented spatiotemporal resolution. Application of this technology will enhance the understanding of healthy brain function, treatment of many neural pathologies, {and pre-surgical planning}. For Phase I, the first Specific Aim is to modify EEG electrodes for MR-compatible dense-array InkNet recordings. The new InkNet will take advantage of EGI's patented low-profile 256-channel geodesic sensor net (HCGSN) structure. Two electrode designs will be developed and tested. The first will miniaturize the existing 32-channel InkCap half-ring electrodes to fit the HCGSN structure by embedding the electrode directly into the harness design rather than using an adhesive. The alternative design will interface EGI's pellet electrode to PTF ink leads by gluing it to an interface pad printed with polyimide conductive glue. Both designs will be tested using two abrasion-free skin applications: EGI's current electrolyte-soaked sponges and a novel biopotential hydrogel. Performance tests for high signal-to-noise ratio (SNR) and low drift will determine the best electrode design for the Phase I prototype. The Second Specific Aim is to design new PTF traces for efficient routing of the 256 electrode leads. An autorouter program (SPECCTRA) will test nine router parameters to converge on the optimal trace width and length which will then used to determine the number vias and layers required. A fixed trace width of 5 mils to ensure manufacturability will be achieved by testing for spacing violations during the SPECCTRA routing iterations. The final prototype circuits will be printed using a custom mix of carbon and silver inks tested for optimal dielectric and conductive properties. The Third Specific Aim is to test the new dEEG/fMRI system for safety and data integrity. Safety tests will be performed using finite difference time domain (FDTD) numerical simulations with an anatomically accurate head model, followed by actual temperature measurements in the 7T scanner using a specially developed phantom (CHEMA), high-power TSE imaging sequences to induce RF heating, and a four-channel Fluoroptic Thermometer. After confirming safety, MRI and EEG data integrity will be tested at 3T and 7T field strengths using T1-weighted structural sequence, a resting EEG alpha protocol, and a visual processing study. Analyses will contrast MRI quality with and without the InkNet, and EEG quality within and outside the MR scanner. PUBLIC HEALTH RELEVANCE: The goal of this project is to develop a system for simultaneous measurement of brain activity using two complementary methods: electroencephalography (EEG) and functional magnetic resonance imaging (fMRI). This state-of-the-art system will offer brain scientists and clinicians a safe, non-invasive tool for studying human brain function with unprecedented spatial and temporal precision. This knowledge will help us better understand healthy brain function, treat many disorders (e.g., epilepsy), and improve pre-surgical planning.