PT  - JOURNAL ARTICLE
AU  - Schmidt, Franziska A.
AU  - Mullally, Mary
AU  - Lohmann, Martin
AU  - Hiepe, Patrick
AU  - Kirnaz, Sertac
AU  - Chidambaram, Swathi
AU  - Wipplinger, Christoph
AU  - Härtl, Roger
TI  - Elastic Image Fusion Software to Coregister Preoperatively Planned Pedicle Screws With Intraoperative Computed Tomography Data for Image-Guided Spinal Surgery
AID  - 10.14444/8039
DP  - 2021 Mar 23
TA  - International Journal of Spine Surgery
PG  - 8039
4099  - https://www.ijssurgery.com/content/early/2021/03/19/8039.short
4100  - https://www.ijssurgery.com/content/early/2021/03/19/8039.full
AB  - Background 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.Methods A total of 12 patients, were selected depending on the availability of a preoperative spinal computed tomography (CT0 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.Results 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.Conclusion Elastic fusion provides high registration accuracy and represents a considerable step towards efficiency and safety in CT-based image-guided surgery.Level of Evidence 3.