Department of Radiology, Brigham and Women's Hospital and Harvard Medical School, 75 Francis St., Boston, MA, USA.
Physical Sciences Inc., 20 New England Bus Center Dr, Andover, MA, USA.
Med Phys. 2021 May;48(5):2553-2565. doi: 10.1002/mp.14816. Epub 2021 Mar 24.
Magnetic resonance imaging (MRI)-guided transperineal prostate biopsy has been practiced since the early 2000s. The technique often suffers from targeting error due to deviation of the needle as a result of physical interaction between the needle and inhomogeneous tissues. Existing needle guide devices, such as a grid template, do not allow choosing an alternative insertion path to mitigate the deviation because of their limited degree-of-freedom (DoF). This study evaluates how an angulated needle insertion path can reduce needle deviation and improve needle placement accuracy.
We extended a robotic needle-guidance device (Smart Template) for in-bore MRI-guided transperineal prostate biopsy. The new Smart Template has a 4-DoF needle-guiding mechanism allowing a translational range of motion of 65 and 58 mm along the vertical and horizontal axis, and a needle rotational motion around the vertical and horizontal axis and a vertical rotational range of , respectively. We defined a path planning strategy, which chooses between straight and angulated insertion paths depending on the anatomical structures on the potential insertion path. We performed (a) a set of experiments to evaluate the device positioning accuracy outside the MR-bore, and (b) an in vivo experiment to evaluate the improvement of targeting accuracy combining straight and angulated insertions in animal models (swine, ).
We analyzed 46 in vivo insertions using either straight or angulated insertions paths. The experiment showed that the proposed strategy of selecting straight or angulated insertions based on the subject's anatomy outperformed the conventional approach of just straight insertions in terms of targeting accuracy (2.4 mm [1.3-3.7] vs 3.9 mm [2.4-5.0] {Median ); p = 0.041 after the bias correction).
The in vivo experiment successfully demonstrated that an angulated needle insertion path could improve needle placement accuracy with a path planning strategy that takes account of the subject-specific anatomical structures.
磁共振成像（MRI）引导经会阴前列腺活检自 21 世纪初以来一直在实践。由于针与不均匀组织之间的物理相互作用导致针的偏差，该技术经常会出现定位错误。现有的针引导装置（如网格模板）由于其自由度（DoF）有限，不允许选择替代的插入路径来减轻偏差。本研究评估了倾斜的针插入路径如何减少针偏差并提高针放置的准确性。
我们扩展了一种用于腔内 MRI 引导经会阴前列腺活检的机器人针引导装置（SmartTemplate）。新的 SmartTemplate 具有 4-DOF 的针引导机构，允许沿垂直和水平轴进行 65 和 58mm 的平移运动，并允许围绕垂直和水平轴进行针旋转运动以及垂直旋转范围分别为 。我们定义了一种路径规划策略，该策略根据潜在插入路径上的解剖结构在直插和斜插之间进行选择。我们进行了（a）一组在 MR 孔外评估设备定位精度的实验，以及（b）一项在动物模型（猪）中评估直插和斜插相结合以提高靶向准确性的体内实验。
我们分析了使用直插或斜插插入路径进行的 46 次体内插入。实验表明，与仅直插相比，基于受检者解剖结构选择直插或斜插的建议策略在靶向准确性方面表现更好（2.4mm [1.3-3.7] 与 3.9mm [2.4-5.0] ；校正偏倚后，p=0.041）。
体内实验成功地证明了，通过考虑特定于受检者的解剖结构的路径规划策略，倾斜的针插入路径可以提高针放置的准确性。
