MRI Technology for Enhanced Radio Frequency Safety

增强射频安全性的 MRI 技术

• 批准号: 8109160
• 负责人: John M. Pauly
• 金额: $ 48.15万
• 依托单位: STANFORD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-09-01 至 2015-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8109160
• 关键词: Adverse event; American; Animal Model; Animals; Anus; Artificial cardiac pacemaker; Brain Injuries; Burn injury; Cardiac; Cations; Chest; Clinical; Clinical Research; Coupling; Defibrillators; Deposition; Development; Devices; Electromagnetics; Engineering; Ensure; Environment; Failure; Frequencies; Fright; Funding; Future; Goals; Guidelines; Head; Heating; Image; Imaging Device; Implant; Improve Access; Incidence; Injury; Lead; MRI Scans; Magnetic Resonance Imaging; Magnetism; Maps; Measurement; Measures; Methods; Monitor; Pacemakers; Patients; Performance; Phase; Physiologic pulse; Positioning Attribute; Problem Solving; Public Health; Radio; Radiofrequency Interstitial Ablation; Reporting; Research; Risk; Safety; Scanning; Series; Solutions; Staging; Stimulus; Structure; Surface; System; Techniques; Technology; Temperature; Testing; Thermometry; Time; Tissues; Variant; Work; absorption; adverse outcome; base; deep brain stimulator; density; design; implantable device; improved; in vivo; magnetic field; patient safety; physical conditioning; physical model; preconditioning; prevent; research study; safety study; sensor; skeletal; transmission process

DESCRIPTION (provided by applicant): The overall goal of this work is to create an MRI imaging environment that eliminates the possibility of RF burns for recipients of cardiac pacemaker, deep brain stimulator, and other neuro-stimulator devices. Today, about 3 million Americans have implanted pacemakers that typically contraindicate any form of head, chest, or muskulo-skeletal MRI scan. Recent clinical safety studies for imaging device recipients at 1.5T have been performed without incident and no related fatalities for pacemakers have occurred since the 1980s. Guidelines for deep brain stimulator recipients typically require head transmit coils and only at 1.5T but at least two MR induced brain injuries have occurred at 1.0T. The general failure to identify adverse outcomes does not prove safety because these results cannot be extrapolated to other field strengths; guidelines are tied to scanner power which is reported inconsistently, and MRI systems lack robust methods of predicting and avoiding potential heating conditions based on physically existing preconditions. Improved engineering of the MR scanner itself can solve this problem. This will require an integration of electromagnetic safety sensors that can independently detect or search for dangerous resonances, MRI RF field mapping methods that can detect lead wire currents responsible for heating but at sensitivities well below physical heating thresholds, and distributed transmit array systems that deposit RF power only where needed. If the physical conditions for heating can be detected and imaged, regardless of field strength, patient orientation, or device, an RF excitation system can be designed to prevent heating. The aims of this research are to: 1) Develop an RF safety prescreen system to detect dangerous interactions before the MRI scan. Integrated external sensor systems will be developed for 1.5T, and extended to 3T. These systems will detect potential resonant device interactions that may produce RF heating and can be used before the patient even enters the MRI scan room. 2) Develop an MRI safety pre-scan to detect and quantify dangerous interactions with a low power MRI scan. MRI pulse sequences will detect and quantify induced RF currents on conductive structures, and use these measurements to grade risk, and predict potential heating for other sequences. 3) Develop safer MRI systems for the future using advanced RF transmission methods. Transmit array excitation systems and optimized pulse sequences will minimize electromagnetic coupling and RF heating near implanted devices. This will be tested in an in vivo animal model at 3T to show that RF currents on an implanted lead can be nulled while providing a sufficiently uniform RF field for imaging. .Ultimately, this work will lead to a clinically testable system. Achieving these goals will substantially increase access to MRI for a broad class of patients with cardiac or neuro-stimulator implants who are currently denied access out of fear of RF heating danger. PUBLIC HEALTH RELEVANCE: Technology to enhance RF safety in MRI scanners- is important to public health because it will enable the 3 million Americans with cardiac pacemakers or deep brain stimulator implants to safely undergo MRI exams without fear of unintended local RF burns. Underutilization of MRI scanners with these patients can be avoided, and the risk of adverse events or unsafe settings can be substantially eliminated.

描述（由申请人提供）：这项工作的总体目标是创建一个MRI成像环境，以消除心脏起搏器，深脑刺激器和其他神经刺激器件的受体RF燃烧的可能性。如今，约有300万美国人植入了起搏器，这些起搏器通常会禁忌任何形式的头部，胸部或穆斯库洛 - 骨骼MRI扫描。对于1.5T进行了成像设备受体的最新临床安全研究，没有发生任何事件，并且自1980年代以来就没有发生过起搏器的相关死亡。深脑刺激器接受者的指南通常需要头部发射线圈，仅在1.5T下，但至少有两次MR诱导的脑损伤发生在1.0T时。总体上无法识别不良结果并不能证明安全性，因为这些结果不能推断到其他现场优势。指南与扫描仪的功率相关，该指南不一致地报道，MRI系统缺乏强大的方法来预测和避免基于物理上现有的先决条件来预测和避免潜在的加热条件。改进的MR扫描仪本身的工程可以解决此问题。这将需要集成电磁安全传感器，该电磁安全传感器可以独立检测或寻找危险的共振，MRI RF现场映射方法可以检测到负责加热的铅线电流，但在敏感性下，远低于物理加热阈值，并分布的发射阵列系统仅在需要的地方沉积RF功率。如果可以检测和成像进行加热的物理状况，而不管野外强度，患者取向或装置，RF激发系统都可以设计以防止加热。这项研究的目的是：1）在MRI扫描之前开发一个RF安全预筛选系统，以检测危险的相互作用。 集成的外部传感器系统将用于1.5T，并扩展到3T。这些系统将检测可能产生RF加热的潜在共振设备相互作用，并且可以在患者进入MRI扫描室之前使用。 2）开发MRI安全前扫描，以检测和量化低功率MRI扫描的危险相互作用。 MRI脉冲序列将在导电结构上检测和量化诱导的RF电流，并使用这些测量值对其他序列进行评分，并预测其他序列的潜在加热。 3）使用高级RF传输方法为未来开发更安全的MRI系统。传输阵列激发系统和优化的脉冲序列将最大程度地减少植入设备附近的电磁耦合和RF加热。这将在3T处的体内动物模型中进行测试，以表明在植入铅上的RF电流可以被取消，同时提供足够均匀的RF场进行成像。最终，这项工作将导致临床测试系统。实现这些目标将大大提高因担心RF加热危险而被拒绝使用的大量心脏或神经刺激植入物患者的MRI访问权限。 公共卫生相关性：提高MRI扫描仪中RF安全性的技术对公共卫生很重要，因为它将使300万美国人具有心脏起搏器或深脑刺激剂植入物，以安全地接受MRI检查，而不必担心当地RF燃烧。可以避免使用这些患者的MRI扫描仪未实现，并且可以大大消除不良事件或不安全设置的风险。