Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37235, USA.
IEEE Trans Biomed Eng. 2011 Mar;58(3):499-508. doi: 10.1109/TBME.2010.2093896. Epub 2010 Nov 22.
Biomechanical models that describe soft tissue deformation provide a relatively inexpensive way to correct registration errors in image-guided neurosurgical systems caused by nonrigid brain shift. Quantifying the factors that cause this deformation to sufficient precision is a challenging task. To circumvent this difficulty, atlas-based methods have been developed recently that allow for uncertainty, yet still capture the first-order effects associated with deformation. The inverse solution is driven by sparse intraoperative surface measurements, which could bias the reconstruction and affect the subsurface accuracy of the model prediction. Studies using intraoperative MR have shown that the deformation in the midline, tentorium, and contralateral hemisphere is relatively small. The dural septa act as rigid membranes supporting the brain parenchyma and compartmentalizing the brain. Accounting for these structures in models may be an important key to improving subsurface shift accuracy. A novel method to segment the tentorium cerebelli will be described, along with the procedure for modeling the dural septa. Results in seven clinical cases show a qualitative improvement in subsurface shift accuracy making the predicted deformation more congruous with previous observations in the literature. The results also suggest a considerably more important role for hyperosmotic drug modeling for the intraoperative shift correction environment.
生物力学模型描述了软组织变形，为纠正图像引导神经外科系统中因脑移位导致的非刚性配准误差提供了一种相对廉价的方法。准确量化导致这种变形的因素是一项具有挑战性的任务。为了规避这一困难，最近开发了基于图谱的方法，这些方法允许存在不确定性，但仍能捕捉到与变形相关的一阶效应。逆解由术中稀疏的表面测量驱动，这可能会导致重建偏差，并影响模型预测的亚表面精度。使用术中磁共振成像的研究表明，中线、小脑幕和对侧半球的变形相对较小。硬脑膜隔作为刚性膜支撑脑实质并分隔脑。在模型中考虑这些结构可能是提高亚表面移位精度的重要关键。本文将描述一种新的小脑幕分割方法，以及硬脑膜隔建模的过程。在七个临床病例中的结果表明，亚表面移位精度的定性改善使预测的变形与文献中的先前观察结果更加一致。结果还表明，在术中移位校正环境中，高渗药物建模的作用更为重要。
