颞下颌关节三维动态磁共振成像研究及生物力学分析

Dynamic MRI study on temporomandibular joint and biomechanical analysis

目的通过在多层面二维动态MR成像上获取颞下颌关节组织的运动数据,构建颞下颌关节的三维动态模型,并进行初步生物力学分析。方法 MRI检查采用GE Signa 1.5T TwinSpeed超导型磁共振扫描仪。选取2例无症状男性志愿者行颞下颌关节MRI检查,将图像数据导入Mimics软件,构建颞下颌关节的三维模型,动态分析张口幅度和关节盘横径的量化关系。结果建立的颞下颌关节三维动态模型清晰显示三维动态盘髁关系及关节盘在动态过程中的形态变化;志愿者1张口/关节盘横径拟合直线为:y=-0.03x+14.44,相关系数R2=0.591,志愿者2相关拟合直线为:y=-0.061x+13.48,相关系数R2=0.306,志愿者张口位置与关节盘横径变化具有直线趋势,关节盘横径随着张口幅度的加大而呈现减小的趋势,颞下颌关节盘对于髁突的包绕程度与张口幅度呈反比。颞下颌关节盘纵径厚度在张口活动中后带外份及中带内份的变化幅度最大。结论通过颞下颌关节二维动态MR成像数据可构建三维动态模型立体动态地观察颞下颌关节运动,可直观、准确显示颞下颌关节盘髁关系,可作为颞下颌关节二维静态MR成像的有益补充,弥补常规MRI检查的局限。

Objective To establish a three-dimensional （3D） dynamic model of temporomandibular joint （TMJ） based on data collected from the TMJ movement with multi-level two-dimensional （2D） dynamic magnetic reso- nance imaging （MRI） and make biomechanical analysis. Methods GE Signal. 5T TwinSpeed superconductive magnetic resonance scanner was used. TMJs of 2 asymptomatic male volunteers were chosen to be examined with MRI. All the images were imported to the Mimics software. 3D dynamic model of the TMJ was built, and the relationship between the magnitude of mouth opening and the disc transverse diameter was analyzed using linear fitting. Results The 3D dynamic model of TMJ was successfully established. The disc-condyle relationship and the dynamic morphological change of the TMJ disc were showed clearly in this model. The linear fitting equations were y = - 0.03x ＋ 14.44 （ R2 ： 0.591 ） and y = - 0. 061 x ＋ 13.48 （ Ff = 0.306） from volunteers 1 and 2, respectively. A linear trend was observed regarding the relationship between mouth opening position and articular disc transverse diameter. The contact of the condyle surrounded by the TMJ disc varied inversely with the magnitude of mouth opening; the longitudinal diameter of TMJ disc changed along with the magnitude of mouth opening. In the process of mouth opening, the thickest longitudinal diameter of the joint disc was at the middle part of postzone. The most remarkable changes of the longitudinal diameter of TMJ disc were found at the outer part of the post-zone and the inner part of the mid-zone. Conclusions The 3D dynamic model of TMJ was built successfullyto observe the TMJ movement dynamically with 2D dynamic MRI. The model showed the disc-condyle relationship intuitively and precisely, and could be used as an alternative method to make up for the shortage of the 2D static MRI.