Ji Songbai, Fan Xiaoyao, Roberts David W, Paulsen Keith D
Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, USA.
Med Image Comput Comput Assist Interv. 2011;14(Pt 1):412-9. doi: 10.1007/978-3-642-23623-5_52.
We present a completely noninvasive technique to estimate soft tissue surface strain by differentiating three-dimensional displacements obtained from optical flow motion tracking using stereo images. The implementation of the strain estimation algorithm was verified with simulated data and its application was illustrated in three open cranial neurosurgical cases, where cortical surface strain induced by arterial blood pressure pulsation was evaluated. Local least squares smoothing was applied to the displacement field prior to strain estimation to reduce the effect of noise during differentiation. Maximum principal strains (epsilon1) of up to 7% were found in the exposed cortical area on average, and the largest strains (up to -18%) occurred near the craniotomy rim with the majority of epsilon1 perpendicular to the boundary, indicating relative stretching along this direction. The technique offers a new approach for soft tissue strain estimation for the purpose of biomechanical characterization.
我们提出了一种完全无创的技术，通过对使用立体图像的光流运动跟踪获得的三维位移进行微分来估计软组织表面应变。应变估计算法的实现通过模拟数据进行了验证，并在三个开放性颅脑神经外科病例中展示了其应用，其中评估了动脉血压脉动引起的皮质表面应变。在应变估计之前，对位移场应用局部最小二乘平滑，以减少微分过程中的噪声影响。平均而言，在暴露的皮质区域发现最大主应变（ε1）高达7%，最大应变（高达-18%）出现在开颅边缘附近，且大多数ε1垂直于边界，表明沿该方向存在相对拉伸。该技术为生物力学特性表征的软组织应变估计提供了一种新方法。
