混合现实腰椎叠合准确性的初步研究

Registration Accuracy of Lumbar Vertebra under 3D Mixed Reality Technique: A Pilot Study

目的可视化技术有助于提高老年患者椎管内穿刺的安全性和成功率。本研究验证混合现实技术下腰椎叠合的准确性,研发用于混合现实引导的腰椎穿刺体位固定垫。方法对真空体位固定垫进行改良设计,使受试者两次侧卧抱膝体位保持基本一致。纳入12例受试者,通过CT扫描观察体位固定误差。采用混合现实技术将CT扫描获得的虚拟3D腰椎图像与受试者叠合,观察虚拟腰椎与受试者真实腰椎的叠合误差。结果12例受试者上标记点的体位误差在x轴、y轴、z轴方向上分别为(0.34±0.28)cm、(0.09±0.06)cm和(0.22±0.12)cm,下标记点在x轴、y轴、z轴的误差分别为(0.29±0.18)cm、(0.08±0.06)cm和(0.18±0.10)cm。虚拟3D腰椎的L3棘突上缘、L3棘突下缘、L4棘突下缘与真实腰椎在x轴方向的叠合误差分别为(0.29±0.17)cm、(0.38±0.25)cm和(0.42±0.35)cm,在z轴方向的叠合误差分别为(0.11±0.09)cm、(0.15±0.13)cm和(0.13±0.10)cm。结论采用改良设计的真空体位固定垫后,两次体位的一致性较好。混合现实引导虚拟3D腰椎与受试者腰椎在头尾方向的叠合误差较小,在左右方向的叠合误差略大,有待进一步改进。

Objective To verify the registration accuracy of lumbar vertebra under 3D mixed reality technique so as to explore a vacuum fixation mat for lumbar puncture.Methods The design of vacuum fixation mat was modified so as to make the subjects keep the same knee-locking and lateral recumbent position in the 2 steps of examination;12 subjects were enrolled and CT scanning was performto confirmbody position fixation with no error;3Dmixed reality technique was applied in overlapping the virtual 3D image of lumbar vertebral capture by CT scanning with the real lumbar vertebral of the subject,and the registration error between the virtual and real lumbar vertebral was observed.Results The position error of the upper marker was(0.34±0.28)cm in x axis,(0.09±0.06)cm in y axis and(0.22±0.12)cm in z axis while the position error of the lower marker was(0.29±0.18)cm in x axis,(0.08±0.06)cm in y axis and(0.18±0.10)cm in z axis;the registration errors of superior border of L3 spinous process,lower border of L3 spinous process and lower border of L4 spinous process in x axis were(0.29±0.17)cm,(0.38±0.25)cm and(0.42±0.35)cm respectively,and those were(0.11±0.09)cm,(0.15±0.13)cm and(0.13±0.10)cm in z axis,respectively.Conclusions The modified vacuum fixation mat produces good consistency of body position in the 2 steps of examination;the registration error between 3D virtual lumbar vertebral and real lumbar vertebral is smaller in z axis but slightly bigger in x axis,which needs further improvement.