Access to scanners for magnetic resonance imaging (MRI) is typically limited by cost and by infrastructure requirements. Here, we report the design and testing of a portable prototype scanner for brain MRI that uses a compact and lightweight permanent rare-earth magnet with a built-in readout field gradient. The 122-kg low-field (80 mT) magnet has a Halbach cylinder design that results in a minimal stray field and requires neither cryogenics nor external power. The built-in magnetic field gradient reduces the reliance on high-power gradient drivers, lowering the overall requirements for power and cooling, and reducing acoustic noise. Imperfections in the encoding fields are mitigated with a generalized iterative image reconstruction technique that leverages previous characterization of the field patterns. In healthy adult volunteers, the scanner can generate T1-weighted, T2-weighted and proton density-weighted brain images with a spatial resolution of 2.2 × 1.3 × 6.8 mm³. Future versions of the scanner could improve the accessibility of brain MRI at the point of care, particularly for critically ill patients.

使用用于磁共振成像 (MRI) 的扫描仪通常受到成本和基础设施要求的限制。在这里，我们报告了用于大脑 MRI 的便携式原型扫描仪的设计和测试，该扫描仪使用具有内置读出场梯度的紧凑轻便的永久稀土磁体。122 公斤的低磁场 (80 mT) 磁体采用 Halbach 圆柱体设计，可产生最小的杂散场，既不需要低温也不需要外部电源。内置磁场梯度减少了对大功率梯度驱动器的依赖，降低了对电源和冷却的总体要求，并降低了噪声。通过利用先前对场模式的表征的广义迭代图像重建技术来减轻编码场中的缺陷。在健康的成年志愿者中，³ . 未来版本的扫描仪可以提高在护理点进行脑部 MRI 的可及性，特别是对于重症患者。