Magnetic actuation provided by the MRI fringe field can be used to navigate micro–tethered instruments into deeper vascular regions. Navigating tethered instruments through the vasculatures to reach deeper physiological locations presently inaccessible would extend the applicability of many medical interventions, including but not limited to local diagnostics, imaging, and therapies. Navigation through narrower vessels requires minimizing the diameter of the instrument, resulting in a decrease of its stiffness until steerability becomes unpractical, while pushing the instrument at the insertion site to counteract the friction forces from the vessel walls caused by the bending of the instrument. To reach beyond the limit of using a pushing force alone, we report a method relying on a complementary directional pulling force at the tip created by gradients resulting from the magnetic fringe field emanating outside a clinical magnetic resonance imaging (MRI) scanner. The pulling force resulting from gradients exceeding 2 tesla per meter in a space that supports human-scale interventions allows the use of smaller magnets, such as the deformable spring as described here, at the tip of the instrument. Directional forces are achieved by robotically positioning the patient at predetermined successive locations inside the fringe field, a method that we refer to as fringe field navigation (FFN). We show through in vitro and in vivo experiments that x-ray–guided FFN could navigate microguidewires through complex vasculatures well beyond the limit of manual procedures and existing magnetic platforms. Our approach facilitated miniaturization of the instrument by replacing the torque from a relatively weak magnetic field with a configuration designed to exploit the superconducting magnet-based directional forces available in clinical MRI rooms.

中文翻译：

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使用临床MRI扫描仪的边缘场可以在较深的血管区域中对栓系器械进行机器人导航

MRI边缘场提供的磁驱动可用于将微系绳器械导航到更深的血管区域。在血管系统中导航系留器械以到达目前无法到达的更深的生理位置，将扩展许多医学干预措施的适用性，包括但不限于局部诊断，影像学和疗法。在较窄的容器中航行需要最小化器械的直径，从而导致其刚度减小，直到转向性变得不切实际，同时在插入位置推动器械以抵消由器械弯曲引起的来自血管壁的摩擦力。为了超出仅使用推力的极限，我们报告了一种方法，该方法依赖于由临床磁共振成像（MRI）扫描仪外部发出的边缘磁场产生的梯度所产生的尖端互补方向拉力。在支持人类规模干预的空间中，每米超过2特斯拉的梯度产生的拉力允许在器械尖端使用较小的磁体，例如此处所述的可变形弹簧。通过将患者自动定位在边缘场内预定的连续位置来获得方向力，这种方法称为边缘场导航（FFN）。通过体外和体内实验，我们证明了X射线引导的FFN可以在复杂的脉管系统中导航微导丝，远远超出了手动程序和现有磁平台的限制。