Bilateral 4D visualization of human temporomandibular joints using a novel multi-slice real-time MRI procedure - A comparative analysis of the intraoral masticatory forces of subjects with and without anterior disk displacement

本研究的目的是对咀嚼过程中关节盘前移位患者的双侧颞下颌关节结构进行动态4D实时可视化。这包括随时间的推移同时显示颞下颌关节，以及三维位置关系，关节盘和所有相邻的颞下颌关节结构的动态变化。目前可用的常规MRI技术允许对静态过程而不是动态过程(即下颌运动)进行可视化，因为相应的数据不是实时获取的；伪动态MRI序列也仅通过耗时的独立静态MRI图像的重建来回溯地产生。然而，临床上可用于记录下颌骨径路的测量系统，如轴位摄影，不能对运动过程中颞下颌关节结构的动态变化做出准确的解剖学结论。Göttingen MPI用于生物物理化学(Jens Frahm教授)的实时磁共振成像技术的发展使每帧高空间分辨率的磁共振成像采集时间约为20-60毫秒。作为与Frahm教授合作的一部分，我们的团队已经能够实施这项创新技术来分析健康志愿者在咀嚼运动过程中的高分辨率MRI视频序列。由于在计算机性能(旁路计算机)、图像重建技术(闪存、非线性逆重建)以及改进的软件和硬件组件方面的进一步进步，我们现在已经成功地在多个图像平面上同时获取了双侧MRI数据。我们希望在这里介绍的项目中应用这种扩展的多层实时MRI程序，以实现对颞颌关节功能的生理和病理生理过程的四维实时洞察。为了研究咀嚼过程中单侧和双侧颞下颌关节结构病变对生物力学的影响，首次实现了双侧颞下颌关节相互作用的可视化研究。此前，由于技术限制，这不是一种选择。本文介绍的方法代表了影像诊断学的最先进水平，并使人们能够得出关于人类颞下颌关节基础研究中的生物力学关系的结论。通过这种新的方法，可以清楚地描述有和没有盘移位的受试者的颞下颌关节的生物力学。根据研究结果，应该检验这一假设，即与对照组相比，关节盘移位的受试者关节面上存在更大的力。

The aim of the present study is the bilateral dynamic 4D real-time visualization of the temporomandibular joint structures of patients with anterior disk displacement during the chewing process. This includes the simultaneous visualization of both temporomandibular joints over time as well as the three-dimensional positional relationship, the dynamic changes of the discus articularis and all adjacent temporomandibular joint structures. The currently available conventional MRI techniques allow the visualization of static rather than dynamic processes (i.e., mandibular movements) because the corresponding data is not acquired in real time; pseudodynamic MRI sequences are also retrospectively produced only by time-consuming reconstruction of independent static MRI images. Clinically applicable measuring systems for the recording of mandibular pathways, such as the axiography, however, do not allow precise anatomical conclusions on the dynamic changes of the temporomandibular joint structures during movement. The development of real-time MRI technology at the Göttingen MPI for Biophysical Chemistry (Prof. Jens Frahm) enables an MRI acquisition time of approximately 20-60 milliseconds per frame with a high spatial resolution. As part of a collaboration with Prof. Frahm, our group has been able to implement this innovative technique to analyze high-resolution MRI video sequences of the temporomandibular joint in healthy volunteers during the chewing movement. Due to further advances in computer performance (bypass computers), image reconstruction techniques (FLASH, non-linear inverse reconstruction) as well as modified software and hardware components we have now succeeded in acquiring simultaneous bilateral MRI data in several image planes. We would like to apply this extended multi-slice real-time MRI procedure in the project presented here to enable four-dimensional real-time insights into physiological and pathophysiological processes of temporomandibular joint functions. For the first time, the interaction of both temporomandibular joints can be simultaneously visualized in order to investigate the biomechanical influence of unilateral and bilateral pathological changes in temporomandibular joint structures during mastication. This had not previously been an option due to technical limitations. The method presented here represents the state of the art in imaging diagnostics and enables conclusions to about biomechanical relationships in fundamental research on the human temporomandibular joint. By using this novel method, the biomechanics of the temporomandibular joint in subjects with and without disc displacements can be clearly described. On the basis of the results, the hypothesis should be tested that there is larger force on the articular surfaces in subjects with disc displacement in relation to subjects of the control group.