B型夹层TEVAR后假腔重塑的力学评价和预测

Type-B complicated aortic dissection is a severe vascular disease with high morbidity and mortality. In this particular type of aortic dissection, the dissection often involves abdominal aorta or even further distal arteries. Thoracic endovascular aortic repair (TEVAR) is the common treatment applied in this disease. However, part of the patients may find false lumen enlargement after TEVAR, especially in the abdominal aorta. The development of false lumen has direct relation with the local hemodynamics. In this project, we investigate a number of type-B complicated aortic dissection cases with long-term multiple follow-up data (more than 40 patient cases and more than 5-year follow-up). The patient cases will be classified into the enlarged and stable groups according to the mid-term development of false lumen post-TEVAR. Patient-specific models will be established based on CTA datasets and morphological analysis will be conducted. Hemodynamic analysis is then applied on the patient-specific models. The velocity boundary conditions will be supplied by 4D phase contrast MR and Doppler ultrasound velocimetry. The computational results will be validated by both medical velocimetry and in vitro cardiovascular experiments. Besides, a hemodynamics-based thrombosis model will be established to predict long-term thrombosis formation in the false lumen. This will be validated by the long-term follow-up of the patients. This may contribute to accurate evaluation and prediction on dissection development and thus assists early decision-making on re-intervention or surgery.

B型主动脉夹层是一类高危血管疾病，其夹层常延伸至腹主动脉及以远。胸主动脉腔内修复术是其常用微创治疗方法，但术后部分患者会出现支架远端残余假腔继续生长，这与假腔局部血液动力学有直接关系。本课题将结合已往病例，筛选B型夹层长期多次随访病例（≥40例，≥5年）并根据残余假腔中期转归情况进行分组研究：1）基于CTA建立各随访病例个体化模型并做形态学参数分析；2）进行血液动力学仿真分析，结合4D PC-MRI和多普勒超声测速建立仿真模型速度边界；3）通过体外仿生循环实验和医学测速对力学仿真进行验证，确定力学参数的随访变化与分组结果的对应，提出可预判远期假腔转归趋势的力学参数；4）建立基于血液动力学参数的假腔血栓化模型，与随访结果对比验证，实现对远期假腔血栓化程度的预测。此研究可为假腔发展状态提供预测性力学判据和血栓化模拟，辅助对支架以远假腔二次干预必要性的早期判断，从而辅助优化B型夹层的诊疗。

B型主动脉夹层（aortic dissection, AD）是一类高危血管疾病，其夹层常延伸至腹主动脉及以远。胸主动脉腔内修复术（thoracic aortic endovascular repair, TEVAR）是其最常用的微创治疗方法，但术后部分患者会出现支架远端残余假腔继续生长，这与假腔局部血液动力学有直接关系。本课题筛选出B型AD长期多次随访病例，根据残余假腔中期转归情况进行分组研究：1）基于CTA建立各随访病例个体化模型并做形态学参数分析；2）以多普勒超声测速建立仿真模型速度边界，进行血液动力学仿真分析；3）通过体外仿生循环实验和医学测速对力学仿真进行验证。课题经过4年执行，我们获得以下重要研究结果：1）提出了一种新型B型AD多阶段计算机框架分割方法，基于深度学习完成AD自动分割与真假腔识别分离，其模型精确度（Dice分数）可达95%；2）基于Simplex网格和力学接触模型，开发了一种快速虚拟支架植入算法，可用于模拟支架导致的B型AD的真假腔形变；3）提出并验证了可预判TEVAR后远期假腔转归趋势的功能学参数（真假腔第一压力平衡点），并确认其位移可预测术后真腔容积增大、假腔容积减小趋势；4）搭建了以患者为单位的主动脉夹层患者数据管理平台，完成了智能分割算法的嵌入，形成可服务于数据管理、数据标注、自动图像分割、自动三维形态学参数输出的可应用系统；5）研发了高度模拟人体动脉生理的体外仿生循环系统，接入猪主动脉体外B型AD模型，构建了标准化的大型哺乳动脉体外模型。本课题研究结果的科学意义在于发现决定B型AD TEVAR安全性和有效性的功能学参数，其临床价值在于对B型AD的手术规划、支架选择、手术风险评估、预后及二次干预方案的快速化、智能化、个体化、精准化提供了数据库和研究方法的支持，今后可实现B型AD智能诊疗系统的临床转化，从而辅助优化B型AD的诊疗。