Brandão Sofia, Parente Marco, Silva Elisabete, Da Roza Thuane, Mascarenhas Teresa, Leitão João, Cunha João, Natal Jorge Renato, Nunes Rita Gouveia
Department of Radiology, Centro Hospitalar de São João - EPE, Faculty of Medicine, University of Porto, Alameda Prof. Hernâni Monteiro, 4200-319, Porto, Portugal.
Associated Laboratory for Energy, Transports and Aeronautics (LAETA), Institute of Science and Innovation in Mechanical and Industrial Engineering (INEGI), Faculty of Engineering, University of Porto, Rua Dr Roberto Frias, 400, 4200-465, Porto, Portugal.
Ann Biomed Eng. 2017 May;45(5):1255-1265. doi: 10.1007/s10439-016-1788-y. Epub 2017 Jan 17.
Biomechanical analysis of pelvic floor dysfunction requires knowledge of certain biomechanical parameters, such as muscle fiber direction, in order to adequately model function. Magnetic resonance (MR) diffusion tensor imaging (DTI) provides an estimate of overall muscle fiber directionality based on the mathematical description of water diffusivity. This work aimed at evaluating the concurrence between pubovisceralis muscle fiber representations obtained from DTI, and the maximum principal stress lines obtained through the finite element method. Seven datasets from axial T2-weighted images were used to build numerical models, and muscle fiber orientation estimated from the DT images. The in-plane projections of the first eigenvector of both vector fields describing muscle fiber orientation were extracted and compared. The directional consistency was evaluated by calculating the angle between the normalized vectors for the entire muscle and also for the right and left insertions, middle portions, and anorectal area. The values varied between 28° ± 6 (right middle portion) and 34° ± 9 (anorectal area), and were higher than the angular precision of the DT estimates, evaluated using wild bootstrapping analysis. Angular dispersion ranged from 17° ± 4 (left middle portion) to 23° ± 5 (anorectal area). Further studies are needed to examine acceptability of these differences when integrating the vectors estimated from DTI in the numerical analysis.
盆底功能障碍的生物力学分析需要了解某些生物力学参数，如肌纤维方向，以便对功能进行充分建模。磁共振（MR）扩散张量成像（DTI）基于水扩散率的数学描述，提供了对整体肌纤维方向性的估计。这项工作旨在评估从DTI获得的耻骨内脏肌纤维表示与通过有限元方法获得的最大主应力线之间的一致性。使用来自轴向T2加权图像的七个数据集构建数值模型，并从DT图像估计肌纤维方向。提取并比较描述肌纤维方向的两个向量场的第一特征向量的平面投影。通过计算整个肌肉以及左右插入部、中间部分和肛门直肠区域的归一化向量之间的角度来评估方向一致性。这些值在28°±6（右中间部分）和34°±9（肛门直肠区域）之间变化，并且高于使用野生自举分析评估的DT估计的角度精度。角度离散范围从17°±4（左中间部分）到23°±5（肛门直肠区域）。在数值分析中整合从DTI估计的向量时，需要进一步研究来检验这些差异的可接受性。
