Technology for Portable MRI

描述（由申请人提供）：磁共振成像（MRI）自30多年前问世以来，一直是检测和诊断神经系统疾病和损伤的无可争议的护理标准。然而，MRI扫描仪的成本、重量、尺寸和维护需求通常使其无法在一些可能最需要的地方使用-包括急诊室、神经重症监护室（ICU）、手术室、运动场、战场、农村医疗保健场所和救护车。事实上，目前还没有真正便携的“即时”MRI系统，尽管有几个小组试图简化和简化MRI扫描仪组件。需要一种新的方法来创建这样一个真正便携式，负担得起的大脑扫描仪，在这里被称为“便携式大脑扫描仪”（PBS）。然而，使常规扫描仪便携的问题不仅是需要大的、高度均匀的磁场（需要使用多吨磁体和低温设备），而且是可切换梯度编码场的重量和功耗要求（额外的一吨重量和高达2 MW的峰值功率）。在这项工作中，我们完善了我们的概念验证原型PBS，并在试点临床测试中，验证它作为一个低成本，即时MRI扫描仪，可以放置在几乎任何地方。我们采用的方法，使磁铁的磁场均匀性要求放宽约1000倍。这允许没有制冷剂或功耗的轻质永磁体设计。我们的大脑磁铁原型仅重45公斤。我们实现了图像编码，并消除了沉重的，功耗梯度线圈，通过旋转这个不均匀的磁场在头部周围使用磁铁的磁场不均匀性空间调制信号在一个广义的方式相比，与传统的成像梯度。具体来说，主磁体的场不均匀性作为编码场，并且图像被重建为迭代逆问题。这种设计“一石二鸟”，因为它既简化了磁体又消除了梯度线圈， 从而产生真正的“即时”脑部MRI扫描仪。我们通过添加真正的并行接收来进一步改进这种设计，以改善空间编码，以及通过添加TRASE编码用于第三维。该原型的初步临床评价将在急诊科的一组轻度至中度出血性脑损伤患者和神经重症监护室的稳定围手术期结构性病变患者中进行。

DESCRIPTION (provided by applicant): Magnetic Resonance Imaging (MRI) has been the undisputed standard of care for the detection and diagnosis of neurological disorders and injuries since its inception over 3 decades ago. The cost, weight, size, and maintenance needs of MRI scanners, however, typically precludes their use in some locations with perhaps the greatest need - including Emergency Departments, Neurological Intensive Care Units (ICUs), surgical suites, sports fields, battlefields, rural healthcare sites, and ambulances. Indeed, no truly portable, "point-of-care" MRI system currently exists, despite attempts by several groups to miniaturize and simplify MRI scanner components. A new approach is needed to create such a truly portable, affordable brain scanner, referred to here as the "Portable Brain Scanner" (PBS). The problem, however, with rendering conventional scanners portable is not only the requirement for a large, highly homogeneous magnetic field (necessitating the use of multi ton magnets and cryogenic apparatus), but also, the weight and power consumption requirements of switchable gradient encoding fields (an additional ton of weight and up to 2 MW of peak power). In this work, we refine our proof-of-concept prototype PBS and, in pilot clinical testing, validate it as a low cost, point-of-care MRI scanner that can be sited almost anywhere. We employ an approach whereby the magnet's field homogeneity requirements are relaxed approximately 1000 fold. This allows a lightweight, permanent magnet design with no cryogens or power consumption. Our prototype brain magnet weighs just 45kg. We achieve image encoding and eliminate the heavy, power consuming gradient coil, by rotating this inhomogeneous field around the head using the magnet's field inhomogeneity to spatially modulate the signal in a generalized fashion compared to what is done with conventional imaging gradients. Specifically, the field inhomogeneities of the main magnet serve as the encoding field, and the image is reconstructed as an iterative inverse problem. This design "kills two birds with one stone", in that it both simplifies the magnet and eliminates the gradient coil - resulting in a truly "point-of-care" brain MRI scanner. We further refine this design by adding truly parallel reception, to improve spatial encoding, as well as by adding TRASE encoding for the third dimension. Preliminary clinical evaluation of this prototype will be performed on a cohort of patients with mild-to-moderate hemorrhagic brain injury in the Emergency Department, and in stable peri-operative patients with structural lesions in the Neurological Intensive Care Unit.