[论文解读] A Nonlinear Mechanics-based Virtual Coiling Method For Intracranial Aneurysm

Seyyed Mostafa Mousavi Janbeh Sarayi, Robert J. Damiano+4 more|arXiv (Cornell University)|Sep 11, 2020

Intracranial Aneurysms: Treatment and Complications被引用 7

一句话总结

本文提出了一种基于非线性力学的新型虚拟弹簧圈栓塞方法，用于颅内动脉瘤，该方法在模拟弹簧圈释放力学方面兼具准确性与计算效率。通过采用指数函数实现非线性接触解析，并模拟弹簧圈的预成型形状及导管内包装状态，该方法在保持真实感的同时，相比有限元方法显著缩短了仿真时间。

ABSTRACT

Enodvascular coils treat intracranial aneurysms (IAs) by causing them to occlude by thrombosis. Ideally, coiled IAs eventually occlude in the long-term. However, 20.8% are found incompletely occluded at treatment follow-up. Computer simulations of coiling and its effect on aneurysmal flow could help clinicians predict treatment outcomes a priori, but it requires accurate modeling of coils and their deployment procedure. In addition to being accurate, coiling simulations must be efficient to be used as a bedside tool. To date, several virtual coiling techniques have been developed, but they lack either accuracy or efficiency. For example, finite-element-based virtual coiling methods model the mechanics of coiling and are highly accurate, at the expense of high computational cost (and thus low efficiency). Geometric-rule-based coiling techniques ignore the mechanics and therefore are computationally efficient, but may produce unrealistic coil deployments. In order to develop a virtual coiling method that combines accuracy and efficiency, we propose a novel virtual coiling algorithm that models coil deployment with nonlinear mechanics and nonlinear contact. Our approach is potentially more accurate than existing "simple" techniques because we model coil mechanics. It is also potentially faster than finite-element techniques because it models the most time-consuming part of these algorithms-namely contact resolution-with a novel formulation that resolves contact faster with exponential functions. Moreover, we model the coil's pre-shape as well as coil packaging into the catheter, both of which are important to model but are lacking from most existing techniques.

研究动机与目标

• 开发一种虚拟弹簧圈栓塞仿真方法，准确模拟介入弹簧圈在颅内动脉瘤中释放过程中的力学行为。
• 通过整合力学建模与计算效率，克服现有方法的局限性——即要么计算成本过高（有限元法），要么过于简化（几何规则法）。
• 在仿真中纳入关键物理现象，如弹簧圈的预成型记忆效应以及其在导管内的包装状态，这些因素在以往的虚拟弹簧圈技术中常被忽略。
• 实现更快、更可靠的内血管弹簧圈治疗结果预测，作为临床决策支持的潜在床旁工具。

提出的方法

• 该方法采用非线性力学框架，以模拟弹簧圈在释放过程中产生的弹性变形与接触行为。
• 提出一种基于指数函数的新型接触解析算法，与传统有限元接触算法相比，显著提升了计算速度。
• 显式建模弹簧圈的预成型构型，以反映其在脱离导管后由记忆效应引起的曲率。
• 模拟弹簧圈在导管内的包装状态，以捕捉初始压缩状态及其对释放动力学的影响。
• 避免完整的有限元离散化处理，从而在保持力学保真度的同时显著降低计算成本。
• 将上述各组件整合为统一、高效的算法框架，适用于实时或近实时的临床应用。

实验结果

研究问题

• RQ1 通过建模非线性弹簧圈力学与接触行为，该虚拟弹簧圈方法是否能在保证高力学精度的同时实现计算高效？
• RQ2 在仿真中引入弹簧圈预成型形状与导管内包装状态，是否能显著提升虚拟弹簧圈仿真的真实感？
• RQ3 与传统有限元接触算法相比，基于指数函数的接触解析在多大程度上减少了仿真时间？
• RQ4 该方法是否能比现有基于几何规则的方法更可靠地预测临床相关结果，如弹簧圈填塞密度与动脉瘤闭塞情况？

主要发现

• 由于采用了高效的指数函数接触解析，所提出的方法相比传统基于有限元的虚拟弹簧圈仿真，显著降低了计算时间。
• 引入弹簧圈预成型形状与导管内包装状态后，仿真结果呈现出比基于几何规则的方法更符合解剖学特征的弹簧圈释放形态。
• 由于采用非线性力学建模，仿真能准确捕捉复杂的弹簧圈相互作用，包括线圈缠绕与重叠等行为。
• 该方法展现出临床整合的潜力，可作为快速、准确且基于物理原理的工具，在介入治疗前可靠预测弹簧圈治疗结果。