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个低轮廓，高电阻，mri兼容的密集阵列脑电图传感器网络，用于同时记录高达7特斯拉的dEEG/fMRI。这种新型传感器网络（256通道InkNet）将使用印刷在聚合物厚膜（PTF）上的创新导电墨水导线，该技术是由马萨诸塞州综合医院A. A. Martinos中心模拟脑成像实验室（ABILAB）开发的。InkNet将与电气测地线公司（EGI）最近开发的dEEG mri兼容硬件和软件相连接。该系统将为临床医生和研究人员提供安全、无创、价格合理的dEEG/fMRI技术，从而实现以前所未有的时空分辨率对人脑功能进行常规多模态成像。这项技术的应用将增强对健康大脑功能的理解，治疗许多神经病变，以及术前计划。对于第一阶段，第一个特定目标是修改脑电图电极，用于核磁共振兼容的密集阵列InkNet记录。新的InkNet将利用EGI专利的低轮廓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。第一种是将现有的32通道InkCap半环电极小型化，通过将电极直接嵌入线束设计而不是使用粘合剂来适应HCGSN结构。另一种设计将通过将EGI的颗粒电极粘合到用聚酰亚胺导电胶印刷的界面垫上，将其与PTF油墨引线连接。这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走线，以有效地布线256个电极引线。autoouter程序（spectra）将测试9个路由器参数，以收敛于最佳走线宽度和长度，然后用于确定所需的过孔数量和层数。固定走线宽度为5密耳，以确保可制造性，将通过在spectra路由迭代期间测试间距违规来实现。最终的原型电路将使用定制的碳和银墨水混合印刷，以测试最佳的介电和导电性能。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。安全性测试将使用解剖学精确的头部模型进行有限差分时域（FDTD）数值模拟，随后使用专门开发的模体（CHEMA）在7T扫描仪中进行实际温度测量，高功率TSE成像序列诱导射频加热，以及四通道荧光光学温度计。在确认安全性后，将使用t1加权结构序列、静息EEG α协议和视觉处理研究，在3T和7T场强下测试MRI和EEG数据的完整性。分析将对比使用和不使用InkNet的MRI质量，以及在MR扫描仪内和外的EEG质量。

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.