Using external actuation sources to navigate untethered drug-eluting microrobots in the bloodstream offers great promise in improving the selectivity of drug delivery, especially in oncology, but the current field forces are difficult to maintain with enough strength inside the human body (>70-centimeter-diameter range) to achieve this operation. Here, we present an algorithm to predict the optimal patient position with respect to gravity during endovascular microrobot navigation. Magnetic resonance navigation, using magnetic field gradients in clinical magnetic resonance imaging (MRI), is combined with the algorithm to improve the targeting efficiency of magnetic microrobots (MMRs). Using a dedicated microparticle injector, a high-precision MRI-compatible balloon inflation system, and a clinical MRI, MMRs were successfully steered into targeted lobes via the hepatic arteries of living pigs. The distribution ratio of the microrobots (roughly 2000 MMRs per pig) in the right liver lobe increased from 47.7 to 86.4% and increased in the left lobe from 52.2 to 84.1%. After passing through multiple vascular bifurcations, the number of MMRs reaching four different target liver lobes had a 1.7- to 2.6-fold increase in the navigation groups compared with the control group. Performing simulations on 19 patients with hepatocellular carcinoma (HCC) demonstrated that the proposed technique can meet the need for hepatic embolization in patients with HCC. Our technology offers selectable direction for actuator-based navigation of microrobots at the human scale.

中文翻译：

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磁性微型机器人在肝动脉中的人体规模导航

使用外部驱动源来导航血液中不受束缚的药物洗脱微型机器人，为提高药物输送的选择性提供了巨大的希望，特别是在肿瘤学领域，但目前的场力很难在人体内维持足够的强度（> 70厘米） -直径范围）来实现此操作。在这里，我们提出了一种算法来预测血管内微型机器人导航期间相对于重力的最佳患者位置。磁共振导航利用临床磁共振成像（MRI）中的磁场梯度与算法相结合，以提高磁性微型机器人（MMR）的瞄准效率。使用专用的微粒注射器、高精度 MRI 兼容球囊充气系统和临床 MRI，MMR 成功通过活猪的肝动脉进入目标叶。微型机器人（每头猪大约 2000 个 MMR）在右肝叶的分配比例从 47.7% 增加到 86.4%，在左叶的分配比例从 52.2% 增加到 84.1%。经过多个血管分叉后，到达四个不同目标肝叶的 MMR 数量在导航组中比对照组增加了 1.7 至 2.6 倍。对19例肝细胞癌（HCC）患者进行模拟表明，该技术可以满足HCC患者肝栓塞的需求。我们的技术为人体规模的微型机器人基于执行器的导航提供了可选择的方向。