Department of Biomedical Engineering, University of Alberta, 1098 Research Transition Facility, 8308-114 Street, Edmonton, AB, T6G 2V2, Canada.
Department of Physical Therapy, Faculty of Rehabilitation Medicine, University of Alberta, 2-50 Corbett Hall, Edmonton, AB, T6G2G4, Canada.
Int J Comput Assist Radiol Surg. 2022 Feb;17(2):271-281. doi: 10.1007/s11548-021-02516-9. Epub 2021 Nov 2.
Posterior spinal fusion surgery is required to correct severe idiopathic scoliosis. The surgery involves insertion of screws which requires high accuracy to prevent neurologic damage to the spinal cord. Although conventional CT navigation can reduce this risk, 3D-ultrasound-based navigation could achieve this without added ionizing radiation and usage of expensive and bulky equipment. This study aimed to evaluate the accuracy of a 3D ultrasound navigation system for posterior spine surgery.
A custom 3D ultrasound (3DUS) with model-to-surface registration algorithm was developed and integrated into a 3D navigation environment. A CT scan of an adolescent spine (T3-T11) was segmented and 3D printed for experiments. A probe with reflective markers was placed in vertebral pedicles 684 times in varying levels, positions in the capture space and orientation of vertebra, and the entrypoint and trajectory accuracies were measured.
Among 684 probe placements in vertebral levels T3 to T11 in the phantom spine, 95.5% were within 1 mm and 5° of accuracy, with an average accuracy of 0.4 ± 0.4 mm and 2.1 ± 0.9°, requiring 8.8 s to process. Accuracies were statistically significantly affected by vertebral orientation and position in the capture volume, though this was still within the targeted accuracies of 1 mm and 5°.
This preliminary ultrasound-based navigation system is accurate and fast enough for guiding placement of pedicle screws into the spine in posterior fusion surgery. The current results are limited to phantom spines, and future study in animal or human cadavers is needed to investigate soft tissue effects on registration accuracy.
为了矫正严重的特发性脊柱侧凸，需要进行后路脊柱融合手术。该手术需要插入螺钉，这需要高度的准确性，以防止脊髓的神经损伤。虽然传统的 CT 导航可以降低这种风险，但基于 3D 超声的导航可以在不增加电离辐射和使用昂贵且庞大的设备的情况下实现这一目标。本研究旨在评估一种用于后路脊柱手术的 3D 超声导航系统的准确性。
开发了一种具有模型到表面配准算法的定制 3D 超声（3DUS），并将其集成到 3D 导航环境中。对一名青少年脊柱（T3-T11）进行 CT 扫描，并对其进行分割和 3D 打印，用于实验。将带有反射标记的探头放置在椎弓根内 684 次，位置在捕获空间中不同的水平、位置和椎骨的方向，并测量进入点和轨迹的准确性。
在模拟脊柱的 T3 到 T11 椎骨水平上，有 95.5%的探头位置精度在 1 毫米以内，5 度以内，平均精度为 0.4±0.4 毫米和 2.1±0.9 度，处理时间为 8.8 秒。准确性受到椎骨方向和在捕获体积中的位置的显著影响，但仍在 1 毫米和 5 度的目标精度范围内。
这种基于超声的初步导航系统对于指导后路融合手术中椎弓根螺钉的置入是准确和快速的。目前的结果仅限于模拟脊柱，需要在动物或人体尸体上进行进一步的研究，以调查软组织对配准精度的影响。
