基于磁共振图像的人体骨盆三维重建及有效性验证

Three-dimension Reconstruction and Verification of Finite Element Model of Human Pelvis Based on MR Images

目的:利用磁共振图像重建人体骨盆,并利用有限元方法验证建立该模型的有效性,为临床上不适合CT扫描的患者,提供了从MRI图像重建人体模型和骨盆生物力学研究的另一种方法。方法:采用1.5T的核磁成像仪扫描获取正常骨盆MRI图像,利用Hypermesh进行网格划分和韧带添加,采用Mimics和Geomagic对图像数据进行重建。对模型施加适当的界条件,运用有限元分析方法,分析该模型的应力应变和位移结果,同实验测量文献和CT重建的模型有限元模型结果对比。结果:骨盆上关键点的应力应变和位移数值基本吻合引用的参考文献对应点数值,趋势基本相似。坐位时,垂直加载600 N载荷于骶骨上表面,应力由骶骨经骶髂关节向下传递,经坐骨上支、到达坐骨结节;应力主要集中在坐骨大切迹和坐骨结节。站位时,垂直加载600 N载荷于骶骨上表面,应力分别经骶骨翼、骶髂关节,坐骨大切迹,弓状线,至髋臼;应力主要集中在骶髂关节和坐骨大切迹。结论:成功利用MRI建立的有限元模型,其基本可以反应骨盆的力学结构特点,准确性较高,可以作为用于研究骨盆及其植入物生物力学的基础。站立位时,骨盆的主要负重和稳定结构位于后方;坐位时,骨盆承载人体重量并在上下应力传导中起着非常重要的作用。

Objective：To provide a pelvic reconstruction and verification method including using MR images and finite element method respectively for those who are not suitable for CT scan in the clinic and for the pelvic biomechanics study. Methods： A 1.5 tesla MRI scanner is used to acquire normal pelvis MR images. Then, the Mimics and Geomagic software reconstructs a model. Finally, the Hypermesh software meshes the models and adds attached ligaments. Using properly boundary condition aJad finite element method analyze displacement, strain and stress of the model. Comparing the results with experimental data and CT model verify the effectiveness of MR model. Results：The key point on the MR model has the same stress and strain trend as. the reference data. When we apply vertical distributed load （600N） on the upper terminal plate of the sacrum to simulate sitting position, the stress passed through the sacroiliac joint, superior ramus of ischium and reaching ischial tuberosity. The highest stress was found at the iliosciatic notch and ischial tuberosity during. When we apply the bound- ary condition of standing position, the stress passed through the alae sacralis, sacroiliac joint, greater sciatic notch, arcuate line and reaching acetabulum bone. The highest stress was found at the sacroiliac joint, greater sciatic notch. Conclusions： Recon- structions of the penis based on MR images reflect the features of pelvic biomechanics more accurately and efficiently. This model could be used to further study pelvic biomechanics. In standing position, the main weight loading and stability structure was at the posterior part of pelvis. In sitting stance, the pelvis support body weight and is the key to stress conduction.