MR4DFLOW评估3D打印实体模型流体力学探究乙状窦源性耳鸣血流机制

Sigmoid sinus tinnitus, which is the most common type of vascular tinnitus and seriously affecting the quality of life, has been a difficult problem in clinical diagnosis and treatment. Our preliminary research suggests sigmoid sinus tinnitus is always presenting with sigmoid wall dehiscence with or without diverticulum. Both finite element and entity models were built to explore the mechanism of sigmoid wall dehiscence. New surgical treatment such as dehiscence reconstruction, stent implantation and so on were established, while there were still 36% of patients with poor outcomes. The hemodynamics in sigmoid sinus is thought to be the root cause of sigmoid sinus tinnitus, while the mechanism is unknown. Three dimensional printing vascular structure has been proved to be used in the hydromechanics studies using MR, and four dimensional flow MR is the latest technology for the evaluation of hydromechanics, while no study associated with sigmoid sinus tinnitus has been reported. In this study, digital structures of both temporal bone with dehiscence and venous sinuses including transverse sinus, sigmoid sinus and jugular bulb will be reconstructed based on imaging firstly. Venous sinuses including different types of sigmoid sinuses shape, diverticulum, emissary veins, transverse sinus stenosis and jugular bulb height will be also made. Secondly, three dimensional printing entity structures will be used to build different sigmoid sinus entity models to simulate the process of different sigmoid sinus tinnitus. Then, noise quantified production will be used to measure noise intensity in region of tympanic membrane, while MR 4D flow to obtain the sigmoid sinus’ hydrodynamic information. After all, to evaluate the change of noise intensity and hydrodynamics as models changes, as well as the association between the noise intensity and hydrodynamics, so as to investigate the hemodynamics mechanism of sigmoid sinus tinnitus, which will lay a foundation for innovating safe and effective individualized treatment protocols.

乙状窦源性耳鸣是搏动性耳鸣最常见类型，严重影响生活质量，一直是临床诊疗难题。我们前期研究提示此类耳鸣存在乙状窦骨壁缺失和/或憩室，构建数字及实体模型探究了骨壁缺失作用机制，创建了骨壁修补、支架植入等新手术方案，仍有36%患者疗效不佳；推测乙状窦血流是根本原因，但机制不清。MR 4D FLOW是最新复杂血流评价技术，3D打印血管可用于MR血流评估，未见耳鸣相关报道。本项目拟：①基于影像构建单纯乙状窦骨壁缺失数字结构，在其基础上构建伴不同乙状窦深度、憩室、导静脉、横窦狭窄、颈静脉球高度的静脉窦及颞骨数字结构；②分别3D打印实体结构并构建实体模型，模拟个体化疾病状态；③噪声量化仪获取各模型鼓膜区噪声强度，4D FLOW获取骨壁缺失处乙状窦流体力学信息；④评估不同静脉窦条件下噪声强度、乙状窦流体力学各自变化规律及二者间量化关系，探讨乙状窦源性耳鸣血流作用机制；为创新安全有效个体化治疗方案奠定基础。

乙状窦源性耳鸣严重影响生活质量，一直是临床诊疗难题，发生机制不清。颞骨双期增强CT是首选检查手段；MR 4D FLOW、MR ASL是最新复杂血流评价技术；计算流体力学可体外模拟不同条件下在体血流状态；3D打印血管可真实还原在体血管形态并用于MR血流评估。本项目通过上述技术：①发现了乙状窦源性耳鸣的相关特征，即乙状窦憩室与同侧静脉回流优势并横窦狭窄、乙状窦周骨壁裂缺、乳突区气化不良相关；颅高压性耳鸣与显著的静脉回流优势、同侧乙状窦周骨壁缺失相关；跨狭窄压力梯度与横窦狭窄长度及程度相关；②发现了乙状窦源性耳鸣的脑灌注改变特征，即耳鸣相关的横窦狭窄可导致全脑灌注减低；左侧顶下小叶的脑血流量增加，与耳鸣的严重程度正相关，与耳鸣的侧别无关; ③构建了不同乙状窦深度、导静脉、乙状窦憩室、横窦狭窄、颈静脉球窝高位条件下的计算流体力学模型，分别3D打印实体结构、构建实体模型并行MR 4D FLOW检查，模拟个体化疾病状态，发现了不同憩室深度/角度/位置、不同导静脉位置/血流方向、不同乙状窦深度、不同横窦狭窄程度、不同颈静脉球窝高度对横乙状窦血流速度、壁面压力、血流形式的影响规律；④发现了血流速度与血流形式、跨狭窄压力梯度、壁面压力、骨壁缺失密切相关，是耳鸣噪声发生的关键；构建了多物理场耦合模型，初步分析了噪声与不同因素的量化关系。上述研究有助于提升临床对乙状窦源性耳鸣的全面认识、创新安全有效的治疗方案，从而消除数百万患者的噪声困扰。