基于CT的血管性耳鸣生物力学模型创建及发生机制研究

Vascular pulsatile tinnitus (PT) is a common symptom, which seriously affects the patient's quality of life. Limited knowledge of the mechanism of PT which is not investigated in previous studies, leave clinicians frustrated to make accurate etiological diagnosis and choose effective treatment. Based on our many previous studied, we have suggested blood flow, cortical plate around vessels, and air cells of the temporal bone may be associated with vascular PT. However, there is still no quantitative study of the role of these three factors in vascular PT and specifically report on vascular PT mechanism in previous literatures. In this study, we propose to tackle the problem of difficulty understanding the fundamental mechanism behind vascular PT using highly realistic computer models and real-size object simulation models. First, a vascular PT patient enrolled in this study underwent dual phase contrast enhanced CT, on which vessels, cotical plate aroud vessels, and air cells of the temporal bone can be distinguished easily based on different CT value. Using these CT images as a foundation, we will construct some kinds of 3 dimensional fluid-solid coupling mechanical and finite element analysis models of temporal bone which include sigmoid sinus, various thickness of cortical plate and pneumatized degree of temporal bone. These models will include detail anatomical, hemodynamic, and aerodynamic information. Based on these finite element analysis models, we will inspect the role of the blood flow, the thickness of cortical plate, and the pneumatized degree of temporal bone in the presence of PT respectively and as a whole structure in the presence of vascular PT were studied to reveal the fundamental mechanism and determine key factors and essential conditions of vascular PT. According to the template of mechanical models, we will construct real-size object simulateion models whose anatomical structure are exactly same with that of computer models. Peristaltic pump was used to control hemodynamic in vessel, and signal measuring instrument was used to measure acoustical vibration in the tympanum transmitted from vessel. Beased on these mechanical models, the role of above mentioned three factors respectively and as a whole structure in the presence of vascular PT were studied to verify the results in computer model. Through the above studies, we wish to achieve a significantly improved understanding of PT mechanisms, improve etiological diagnosis characteristic indicators of PT, and provide a theoretical basis for innovative surgical strategies. At the same time, such model system with digital and patient-specific features has hope of becoming the vascular PT surgical planning technique for clinical applications.

血管性耳鸣常见并严重影响生活。因发生机制不明，至今缺乏有效诊治方法。我们大量前期工作发现其影响因素有血管内流场、血管旁骨板、颞骨蜂房，但尚无文献定量化研究上述因素作用机理，更未对血管性耳鸣发生机制专门报道。为此，我们拟利用数值模拟与实体模型实验相结合的方法定量化研究血管性耳鸣的生物力学机制。首先，基于CT图像建立精确的颞骨三维有限元模型，分别定量研究上述各因素对耳鸣声音产生、传导的作用规律及三种因素的组合性效应。其次，构建具有真实解剖结构的颞骨实体模型，蠕动泵控制血流，信号测量仪测量传导至鼓室内的耳鸣信号，与数值模拟结果相互验证。从不同层次定量化阐释血管内流场，血管旁骨板、颞骨蜂房的作用机理，揭示耳鸣发生机制、关键因素和必要条件，进而完善病因诊断特征指标，为创新手术新策略提供理论依据。同时，本课题建立的颞骨三维数值模拟分析系统，将为临床医生规划血管性耳鸣手术方案提供数字化平台。

搏动性耳鸣是一种发病机制不明、严重影响生活的常见耳科疾病。临床对搏动性耳鸣患者的多份统计报告显示，乙状窦内血流流场、乙状窦沟骨板厚度、颞骨蜂房气化程度三者与搏动性耳鸣的产生可能存在着密切关系，但均未从生物力学角度给出机理性的解释，也并未量化三者对搏动性耳鸣的贡献。本项目以量化搏动性耳鸣与乙状窦内血流流场、乙状窦沟骨板厚度、颞骨蜂房气化程度这三种因素的关系为目的，以数值仿真和体外实验两种方式，分别建立乙状窦静脉声的产生、传导的量化三维模型，探究搏动性耳鸣的生物力学病理机制。在数值仿真方法中，本项目应用典型患者的CT、MRI等影像学资料，建立了横窦-乙状窦、乙状窦沟骨板、颞骨蜂房气腔的三维几何模型，用数值仿真方法，依次对横窦-乙状窦内脉动流场、乙状窦沟骨板的振动、静脉声在颞骨蜂房气腔中的传导进行了耦合性仿真，完成了乙状窦静脉声的产生和传导的完整数值仿真模型。在体外实验方法中，本项目应用3D打印技术制作乙状窦血管、乙状窦沟骨板、颞骨蜂房气腔的三维模型，应用自设计系统制造脉动静脉流，录制鼓室接收到的静脉声信号。本项目结果显示：. 1. 以实验证实了横窦-乙状窦交汇处静脉声的产生。在乙状窦骨板缺损6mm情况下，实验录制的静脉声在100-400Hz内呈现脉动性，与临床报道搏动性耳鸣的频率（约500Hz）符合良好。. 2. 中或高静脉血流流量（660ml/min及以上）是导致0.035Pa以上静脉声的必要条件。. 3. 乙状窦沟骨板缺损或严重变薄（0.25mm）是导致0.035Pa静脉声的必要条件。当乙状窦沟骨板缺损或严重变薄时，乙状窦组织（血管壁、骨板）在初阶固有频率会产生高幅值的外表面振动响应，直接导致中度及以上静脉声的产生。. 4. 颞骨蜂房过度气化不是导致较强静脉声的必要条件。三级气化程度的颞骨蜂房对静脉声的传导效果最好，一级气化程度的颞骨蜂房对静脉声的传导效果最差。