Hussein Nabil, Voyer-Nguyen Pascal, Portnoy Sharon, Peel Brandon, Schrauben Eric, Macgowan Christopher, Yoo Shi-Joon
Division of Cardiology, Department of Paediatrics and Division of Cardiovascular Surgery, Department of Surgery, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada.
Center for Image-Guided Innovation and Therapeutic Intervention (CIGITI), Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada.
3D Print Med. 2020 Feb 3;6(1):2. doi: 10.1186/s41205-020-0057-8.
The structure of the valve leaflets and sinuses are crucial in supporting the proper function of the semilunar valve and ensuring leaflet durability. Therefore, an enhanced understanding of the structural characteristics of the semilunar valves is fundamental to the evaluation and staging of semilunar valve pathology, as well as the development of prosthetic or bioprosthetic valves. This paper illustrates the process of combining computer-aided design (CAD), 3D printing and flow assessment with 4-dimensional flow magnetic resonance imaging (MRI) to provide detailed assessment of the structural and hemodynamic characteristics of the normal semilunar valve.
Previously published geometric data on the aortic valve was used to model the 'normal' tricuspid aortic valve with a CAD software package and 3D printed. An MRI compatible flow pump with the capacity to mimic physiological flows was connected to the phantom. A peak flow rate of 100 mL/s and heart rate of 60 beats per minute were used. MRI measurements included cine imaging, 2D and 4D phase-contrast imaging to assess valve motion, flow velocity and complex flow patterns.
Cine MRI data showed normal valve function and competency throughout the cardiac cycle in the 3D-printed phantom. Quantitative analysis of 4D Flow data showed net flow through 2D planes proximal and distal to the valve were very consistent (26.03 mL/s and 26.09 mL/s, respectively). Measurements of net flow value agreed closely with the flow waveform provided to the pump (27.74 mL/s), confirming 4D flow acquisition in relation to the pump output. Peak flow values proximal and distal to the valve were 78.4 mL/s and 63.3 mL/s, respectively. Particle traces of flow from 4D-phase contrast MRI data demonstrated flow through the valve into the ascending aorta and vortices within the aortic sinuses, which are expected during ventricular diastole.
In this proof of concept study, we have demonstrated the ability to generate physiological 3D-printed aortic valve phantoms and evaluate their function with cine- and 4D Flow MRI. This technology can work synergistically with promising tissue engineering research to develop optimal aortic valve replacements, which closely reproduces the complex function of the normal aortic valve.
瓣叶和窦的结构对于支持半月瓣的正常功能及确保瓣叶耐久性至关重要。因此，深入了解半月瓣的结构特征对于半月瓣病变的评估与分期以及人工瓣膜或生物瓣膜的研发至关重要。本文阐述了将计算机辅助设计（CAD）、3D打印及血流评估与四维血流磁共振成像（MRI）相结合的过程，以详细评估正常半月瓣的结构和血流动力学特征。
利用先前发表的主动脉瓣几何数据，通过CAD软件包对“正常”三尖瓣主动脉瓣进行建模并3D打印。将一个能够模拟生理血流的MRI兼容血流泵连接到模型上。使用的峰值流速为100毫升/秒，心率为每分钟60次。MRI测量包括电影成像、二维和四维相位对比成像，以评估瓣膜运动、流速和复杂血流模式。
电影MRI数据显示，3D打印模型在整个心动周期中瓣膜功能正常且无反流。对四维血流数据的定量分析表明，瓣膜近端和远端二维平面的净流量非常一致（分别为26.03毫升/秒和26.09毫升/秒）。净流量值的测量与提供给泵的血流波形密切相符（27.74毫升/秒），证实了与泵输出相关的四维血流采集。瓣膜近端和远端的峰值流速分别为78.4毫升/秒和63.3毫升/秒。四维相位对比MRI数据的血流粒子迹线显示血流通过瓣膜进入升主动脉以及主动脉窦内的涡流，这在心室舒张期是预期的。
在这项概念验证研究中，我们展示了生成生理性3D打印主动脉瓣模型并通过电影和四维血流MRI评估其功能的能力。这项技术可与有前景的组织工程研究协同工作，以开发出能紧密再现正常主动脉瓣复杂功能的最佳主动脉瓣置换物。
