Mechanical Engineering Department, Imperial College London, London SW7 2AZ, United Kingdom.
Bioinspir Biomim. 2018 Feb 16;13(2):026009. doi: 10.1088/1748-3190/aaa6f4.
Puncturing blood vessels during percutaneous intervention in minimally invasive brain surgery can be a life threatening complication. Embedding a forward looking sensor in a rigid needle has been proposed to tackle this problem but, when using a rigid needle, the procedure needs to be interrupted and the needle extracted if a vessel is detected. As an alternative, we propose a novel optical method to detect a vessel in front of a steerable needle. The needle itself is based on a biomimetic, multi-segment design featuring four hollow working channels. Initially, a laser Doppler flowmetry probe is characterized in a tissue phantom with optical properties mimicking those of human gray matter. Experiments are performed to show that the probe has a 2.1 mm penetration depth and a 1 mm off-axis detection range for a blood vessel phantom with 5 mm s flow velocity. This outcome demonstrates that the probe fulfills the minimum requirements for it to be used in conjunction with our needle. A pair of Doppler probes is then embedded in two of the four working channels of the needle and vessel reconstruction is performed using successive measurements to determine the depth and the off-axis position of the vessel from each laser Doppler probe. The off-axis position from each Doppler probe is then used to generate a 'detection circle' per probe, and vessel orientation is predicted using tangent lines between the two. The vessel reconstruction has a depth root mean square error (RMSE) of 0.3 mm and an RMSE of 15° in the angular prediction, showing real promise for a future clinical application of this detection system.
在微创脑外科的经皮介入过程中刺穿血管可能是一种危及生命的并发症。已经提出在刚性针中嵌入一个前瞻性传感器来解决这个问题，但是，当使用刚性针时，如果检测到血管，则需要中断并提取针。作为替代方案，我们提出了一种新颖的光学方法来检测可转向针前的血管。该针本身基于仿生的多节设计，具有四个空心工作通道。最初，在模仿人体灰质光学特性的组织模型中对激光多普勒流速计探头进行了表征。实验表明，探头具有 2.1mm 的穿透深度和 1mm 的离轴检测范围，用于具有 5mm/s 流速的血管模型。该结果表明，该探头满足将其与我们的针一起使用的最低要求。然后，将一对多普勒探头嵌入针的四个工作通道中的两个中，并使用连续测量来确定从每个激光多普勒探头的血管深度和离轴位置。然后，使用每个多普勒探头的离轴位置生成每个探头的“检测圆”，并使用两个之间的切线来预测血管方向。血管重建的深度均方根误差（RMSE）为 0.3mm，角度预测的 RMSE 为 15°，表明该检测系统具有未来临床应用的真正潜力。
