Portable Intraoperative MRI for Neurosurgery

磁共振成像(MRI)是检测和诊断脑部疾病和外科手术计划的金标准方法。神经外科手术是由MRI的术前神经成像密切指导的，它可以准确地定位和描绘病变，绘制关键的脑区图，或探测组织代谢来指导临床处理。虽然手术前的图像会定期在手术室中查阅，但外科医生使用这些地图导航的能力会因手术期间发生的组织变形和脑移位而降低。已经建立了专门的术中MRI套件来解决这一问题，但由于设备和安装的成本以及手术过程中增加的过多时间，这种情况相对较少。后者的结果是需要重新定位患者(使用传统扫描仪，甚至最新一代的低场便携式脑部扫描仪)，或者疏散非MR兼容设备，然后使用轨道驱动的高场扫描仪(如IMRIS系统)重建这些设备。为了解决这一问题，我们开发了一种便携式、超紧凑、低场强的核磁共振扫描仪，用于术中成像。该扫描仪将与商业上可获得的低调立体定向(梅菲尔德式)框架集成在一起，这是大多数神经外科手术所必需的。扫描仪的大小、重量、功率和冷却要求使其可以集成到标准手术室中，而无需特殊的设施修改。它的设计目的是快速与患者接触和脱离，以最大限度地减少与成像相关的时间延迟。“哈尔巴赫穹顶”磁体的低场和自我屏蔽特性消除了从附近疏散铁磁设备的需要，进一步减少了延误。该系统的快速术中成像可以通过向神经导航软件提供图像来直接指导手术，该软件可以识别相对于高分辨率术前图像的组织扭曲(脑移位)，从而允许更准确和完整的手术切除，减少重复手术(回调)。为了有效地与立体定向框架匹配，我们开发了优化的RF线圈，其中包含框架本身的间隙和凹槽，使框架本身与RF兼容。我们还集成了先进的电磁干扰(EMI)缓解解决方案，消除了对射频屏蔽室(用于典型的MRI套房)的需要，从而允许在手术室进行原位成像。我们将开发用于神经外科指导的关键采集序列，例如T2、FLAIR和DWI，以及用于控制台控制和基于人工智能的图像重建的用户友好的软件解决方案。最后，新的扫描仪将通过工作台测量和在拟人幻影和健康受试者中的成像测试来验证。

Magnetic Resonance Imaging (MRI) is the gold-standard method for the detection and diagnosis of brain disease and surgical planning. Neurosurgery is closely guided by preoperative neuroimaging with MRI which can accurately localize and delineate lesions, map functionally critical brain regions, or probe tissue metabolism to guide clinical management. While the preoperative images are regularly consulted in the OR, the surgeon’s ability to navigate with these maps is degraded by tissue deformation and brain shifts that occur during surgery. Dedicated intraoperative MRI suites have been constructed to address this but are relatively rare due to the cost of equipment and installation and the excessive time they add to the surgical procedure. The latter results from the need to either reposition the patient (with conventional scanners or even the latest generation of low-field portable brain scanners) or evacuate non-MR compatible equipment and then re- establish them with a track-driven high-field scanner such as the IMRIS system. To address this, we develop a portable, ultra-compact, low-field MRI scanner for intraoperative imaging. The scanner will be integrated with a commercially available low-profile stereotactic (Mayfield-like) frame that is necessary for most neurological surgeries. The size, weight, power, and cooling requirements of the scanner allow its integration into a standard operating room without special facility modifications. It is designed to rapidly engage and disengage from the patient to minimize time delays associated with imaging. The low-field and self-shielded nature of the “Halbach dome” magnet eliminate the need to evacuate ferromagnetic equipment from the vicinity further minimizing delays. Rapid intraoperative imaging with this system could directly guide the procedure by providing images to neuro-navigation software that identify tissue distortion (brain-shift) relative to high-resolution pre-operative images to allow more accurate and complete surgical resections with decreased repeat surgeries (call-backs). To efficiently mate with the stereotactic frame, we develop optimized RF coils that incorporate gaps and notches for the frame which has itself been made RF compatible. We also integrate an advanced electromagnetic interference (EMI) mitigation solution that obviates the need for an RF-shielded room (used in typical MRI suites) to allow for in situ operating room imaging. We will develop the critical acquisition sequences for neurosurgical guidance, e.g., T2, FLAIR, and DWI, and a user-friendly software solution for console control and ai-based image reconstruction. Finally, the new scanner will be validated with bench measurements and imaging tests in anthropomorphic phantoms and healthy subjects.