Schmidt Franziska A, Mullally Mary, Lohmann Martin, Hiepe Patrick, Kirnaz Sertac, Chidambaram Swathi, Wipplinger Christoph, Härtl Roger
Weill Cornell Brain and Spine Center, Department of Neurological Surgery, Weill Cornell Medical College, New York Presbyterian Hospital, New York, New York.
BrainLAB AG, Munich, Germany.
Int J Spine Surg. 2021 Apr;15(2):295-301. doi: 10.14444/8039. Epub 2021 Mar 23.
For complex spinal cases, especially when robotic guidance is used, preoperative planning of pedicle screws can be helpful. Transfer of these preoperatively planned pedicle screws to intraoperative 3-dimensional imaging is challenging because of changes in anatomic alignment between preoperative supine and intraoperative prone imaging, especially when multiple levels are involved. In the spine, where each individual vertebra is subject to independent movement from adjacent level, rigid image fusion is confined to a single vertebra and can display fusion inaccuracies on adjacent levels. A novel elastic fusion algorithm is introduced to overcome these disadvantages. This study aimed to investigate image registration accuracy of preoperatively planned pedicle screws with an elastic fusion algorithm vs. rigid fusion for intraoperative placement with image-guided surgery.
A total of 12 patients, were selected depending on the availability of a preoperative spinal computed tomography (CT) and an intraoperative AIRO CT scan (BrainLAB AG, Munich, Germany) of the same spinal region. To verify accuracy differences between rigid fusion and elastic fusion 76 bilateral screw trajectories were virtually defined in the preoperative CT image, and they were transferred via either rigid fusion or elastic fusion to the intraoperative CT scan. Accuracy of the transferred screws in the rigid and elastic fusion group was determined by measuring pedicle breaches on the intraoperative CT.
In the rigid fusion group 1.3% of screws showed a breach of less than 2 mm, 9.2% showed breaches between 2 and 4 mm, and 18.4% of the screws showed an error above 4 mm. The elastic fusion group showed no breaches and provided high accuracy between preoperative and intraoperative screw placement.
Elastic fusion provides high registration accuracy and represents a considerable step towards efficiency and safety in CT-based image-guided surgery.
对于复杂的脊柱病例，尤其是在使用机器人引导时，术前规划椎弓根螺钉可能会有所帮助。由于术前仰卧位和术中俯卧位成像之间的解剖对齐变化，将这些术前规划的椎弓根螺钉转移到术中三维成像具有挑战性，尤其是当涉及多个节段时。在脊柱中，每个椎体都可独立于相邻节段移动，刚性图像融合仅限于单个椎体，并且可能在相邻节段显示融合不准确。引入了一种新型弹性融合算法以克服这些缺点。本研究旨在探讨使用弹性融合算法与刚性融合进行术前规划的椎弓根螺钉在术中图像引导手术放置时的图像配准准确性。
根据同一脊柱区域术前脊柱计算机断层扫描（CT）和术中AIRO CT扫描（德国慕尼黑BrainLAB AG公司）的可用性，共选择了12例患者。为了验证刚性融合和弹性融合之间的准确性差异，在术前CT图像中虚拟定义了76条双侧螺钉轨迹，并通过刚性融合或弹性融合将它们转移到术中CT扫描。通过测量术中CT上的椎弓根侵犯情况来确定刚性融合组和弹性融合组中转移螺钉的准确性。
在刚性融合组中，1.3%的螺钉显示侵犯小于2 mm，9.2%的螺钉显示侵犯在2至4 mm之间，18.4%的螺钉显示误差大于4 mm。弹性融合组未显示侵犯情况，并且在术前和术中螺钉放置之间提供了高精度。
弹性融合提供了高配准准确性，代表了基于CT的图像引导手术在效率和安全性方面迈出的重要一步。
3级。
