Portable Intraoperative MRI for Neurosurgery

磁共振成像（MRI）是检测和诊断脑部疾病和制定手术计划的金标准方法。神经外科手术由术前MRI神经成像密切指导，MRI可以准确定位和描绘病变，映射功能关键的脑区域，或探测组织代谢以指导临床管理。虽然在手术室中定期查阅术前图像，但外科医生使用这些标测图导航的能力会因手术期间发生的组织变形和大脑移位而降低。已经构建了专用的术中MRI套件来解决这一问题，但由于设备和安装的成本以及它们给外科手术增加的过多时间，因此相对较少。后者是由于需要重新定位患者（使用传统扫描仪或甚至最新一代的低场便携式脑部扫描仪）或撤离非MR兼容设备，然后使用轨道驱动的高场扫描仪（如IMRIS系统）重新建立它们。 为了解决这个问题，我们开发了一种便携式，超紧凑，低场MRI扫描仪，用于术中成像。扫描仪将与大多数神经外科手术所需的市售低切迹立体定向（Mayfield样）框架集成。扫描仪的尺寸、重量、功率和冷却要求允许其集成到标准手术室中，而无需特殊的设施修改。其设计用于快速接合和脱离患者，以最大限度地减少与成像相关的时间延迟。“Halbach dome”磁体的低场和自屏蔽性质消除了从附近疏散铁磁设备的需要，进一步减少了延迟。使用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，该神经导航软件识别相对于高分辨率术前图像的组织变形（脑移位），以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，该线圈包含框架的间隙和凹口，框架本身具有RF兼容性。我们还集成了先进的电磁干扰（EMI）缓解解决方案，无需使用射频屏蔽室（用于典型的MRI室）来进行原位手术室成像。我们将开发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AI的图像重建的用户友好的软件解决方案。最后，新的扫描仪将在拟人幻影和健康受试者的实验室测量和成像测试进行验证。

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.