人体足主要骨-韧带结构三维有限元模型的建立及分析

目的:建立正常人体足主要骨-韧带结构的三维有限元模型,为足部生物力学研究提供数字平台。材料和方法:获取正常青壮年男性的左足螺旋CT扫描图像,应用逆向工程原理,通过处理序列螺旋CT图片建立足部骨结构的三维几何模型,并对其进行有限元网格划分。足部关节软骨、韧带、肌腱和足底软组织通过解剖和文献数据模拟。同时,对7具新鲜尸体标本足作生物力学测试,分析计算有限元模型及生物力学测试中足部骨骼的应力、位移变化情况。结果:建立了包括170426个节点、118342个单元的关节、骨、软骨、韧带和足底软组织在内的正常人体左足骨骼及韧带结构的三维有限元模型,较客观地反映了人体足的解剖结构和力学特性。与新鲜尸体标本的生物力学测试结果比较,位移变化有相同趋势。结论:运用逆向工程原理可有效构建人体足的三维几何模型,在此基础上基于解剖和离体标本实验结果构建其生物力学有限元模型,可用于足部生物力学变化规律的可视化分析。     

计算机辅助髋关节囊韧带重建三维有限元分析及其生物力学意义

目的 从生物力学角度,采用三维有限元方法,探讨关节囊韧带重建对髋关节的稳定机制.方法 利用功能强大的有限元分析软件Unigraphics NX 2.0和SolidWorks 2006构建出包括坐股韧带重建的全髋关节置换术(total hip arthroplasty,THA)三维有限元模型,模拟坐位腿交叉动作载荷,获取假体脱位过程的角活动度和相应的阻力矩值.结果 所构建坐股韧带为多体连接非线性、大界面划移、高弹性的结构模型,客观反映坐股韧带真实解剖形态及其生物力学行为.增加坐股韧带重建的模型与仅有金属的模型相比,降低了撞击点和脱位点峰应力分别为17%和31%.峰阻力矩增加了57%,并提供了2.29倍的稳定性.结论 坐股韧带作为髋关节后方关节囊一个确切的解剖结构,对后方稳定装置的力学完整性起到重要的作用,髋关节成形术中应该重建髋关节囊韧带.     

人体躯干骨骼-肌肉-韧带结构三维有限元模型的建立和验证

目的:建立正常人体躯干骨-肌肉-韧带三维有限元模型,为脊柱部生物力学研究提供数字平台。方法:获取正常青壮年男性的躯干螺旋CT扫描图像,应用逆向工程原理,通过Mimics、Geomagic软件建立躯干骨结构的三维几何模型;利用ANSYS10.0对其进行有限元网格划分,椎间盘、韧带和肌肉根据解剖学和文献数据模拟,并参照以往文献报道对模型的可靠性进行验证。结果:建立了包括374618个实体单元,110102个壳单元,427个Link单元,22个质点单元,共65998个节点的关节、椎骨、椎间盘和韧带的躯干部三维有限元模型,根据CT灰度值和杨氏模量关系式对松质骨、皮质骨和后部结构进行单独材料赋值,采用等效法构建椎间盘的纤维环。结论:运用逆向工程原理可有效构建人体躯干的三维几何模型,在此基础上基于解剖和离体标本实验结果构建其生物力学有限元模型,可用于人体脊柱生物力学变化规律的可视化分析。     

应用Mimics软件辅助重建人体胸廓三维有限元模型的研究

目的建立人体胸廓三维有限元模型,为研究人体胸外按压的临床效果与机制提供生物力学仿真基础。方法获取1例20岁男性胸部CT扫描图像,将断层影像输入到Mimics10.1软件,利用Mimics软件的三维模型重建和有限元网格辅助划分功能,在Ansys软件中建立完整的人体胸廓三维有限元模型。结果完整重现了人体胸廓的复杂形态,建立了包括锁骨、肋骨、脊柱等结构在内的鲜明、直观的人体胸廓三维有限元模型,共1 158 085个节点、736 022个单元,并依据CT图像灰度值将胸廓模型从骨皮质到髓核区分为6种材料性质。结论利用Mimics软件辅助建立的人体胸廓三维有限元模型具有较高的真实性和精确度,能够满足人体胸廓生物力学分析的需要,为下一步人体胸廓有限元模型的分析提供了基础。     

足部三维有限元模型的建立和跗跖关节模拟碾伤生物力学特性

目的 通过CT数据对人体足部主要结构进行三维有限元模型建立,并对跗跖关节进行准稳态有限元受力分析.方法 对一成年女子行足部螺旋CT扫描,将所得图像经Mimics、GUG、ANSYS等软件处理得到三维有限元数字模型,并对跗跖关节进行准稳态有限元力学分析.结果 建成了足部包括全部骨骼、韧带、皮肤、软组织的三维有限元数字模型,并在正常及模拟碾压伤情况下对跗跖关节进行了有限元应力分析.结论 在正常及模拟碾压伤情况下第二跖骨所受应力最大并集中于第二跖骨基底部.     

基于有限元数值模拟分析的多层螺旋CT扫描技术

有限元分析法是分析大型复杂结构或多自由度体系的有力工具。人体组织结构形态多呈不规则的复杂结构，利用多层螺旋CT扫描的影像资料，通过计算机软件模拟出入体的结构，建立模型并通过计算机软件的网格划分工具进行有限元剖分，通过试验数据对人体结构的模型进行模拟分析，对手术预案的选择以及生物工程制造中具有实际的临床意义。本文通过对多层螺旋CT影像质量分析，获得适合有限元分析法的最佳扫描参数。为有限元数值模拟分析结果提供影像质量保证。     

角质层渗透性质的三维数值模拟

目的从数值模拟的角度研究药物渗透皮肤角质层的过程,为实际的药物工作者提供理论上的指导和帮助。方法用有限元方法离散偏微分方程的差分格式,将角质层的角蛋白细胞近似为物理学上经典的由6个四边形和8个六边形围成的三维十四面体结构,同时将角蛋白细胞间的脂质体视为十四面体结构的一部分,离散其相应的单元网格。结果得到了药物渗透皮肤角质层的三维数值模拟,并给出了模拟过程中浓度和速度变化的可视化效果示意图。结论本文所采用的几何模型与实际的生理结构模型非常接近,数值模拟结果证明这一方法对实际工作有参考意义。     

股骨远端高仿真有限元模型的建立

股骨远端是指股骨下端15 cm以内部分,尽管该部位发生骨折的几率仅占股骨骨折的4％～6％[1],但由于其复杂的解剖结构、生物力学性质以及骨折的高致残率,所以一直受到骨科医生的重视.虽然临床上利用CT图像可以对股骨远端进行三维重建,对骨折治疗有指导意义,却无法直接利用三维图像进行生物力学分析以探讨其受力特点和损伤机制.随着计算机技术的快速发展,有一种通过建立三维有限元模型进行数值分析的方法,即有限元分析法(finite element analysis,FEA)被逐渐应用到人体组织的生物力学分析中,而有限元分析的准确性取决于建模的质量好坏.     

基于CAD技术的个体化下颌骨正交各向异性有限元模型的建立

目的 建立个体化下颌骨正交各向异性三维有限元模型.方法 利用CT薄层扫描下颌骨获取的断层图像数据,在自主开发的USIS软件的基础上,自动分辨骨皮质和骨松质轮廓边界,并对下颌骨采用"非种子区域分割"、非平行"最佳切割曲面"及"B样条曲线拟合法"一系列新型CAD方法进行人机对话自动重建精确的几何表面模型.定义结构材料参数后划分网格,并导入有限元计算软件ANSYS9.0中完成三维有限元建模.结果 建立了结构精确的个体化下颌骨正交各向异性的三维有限元模型.结论 基于CT数据和USIS软件的新型CAD方法实现了个体化下颌骨正交各向异性三维有限元模型的建立.     

螺旋CT三维透明重建对内耳解剖结构的观察

目的　评价螺旋三维RaySum重建技术对内耳解剖结构的显示能力。资料与方法　对 2 0位健康志愿者两侧内耳进行三维RaySum重建 ,沿X轴从 0°开始自前向后每 30°旋转 1次 ,再沿Y轴从 0°开始自上而下每 30°旋转1次 ,观察内耳骨迷路和内听道的解剖结构。结果　内耳三维RaySum重建清楚地显示了椭圆囊、球囊、膜半规管和蜗管等内耳膜迷路的解剖结构。该方法从前向后和从上向下各 12个位置的内耳膜迷路各结构的解剖清晰可见。结论　内耳三维RaySum重建成像能立体而直观地显示内耳膜迷路的解剖结构。     

Intervertebral disc biomechanical analysis using the finite element modeling based on medical images.

In this paper, a 3D geometric model of the intervertebral and lumbar disks has been presented, which integrated the spine CT and MRI data-based anatomical structure. Based on the geometric model, a 3D finite element model of an L1-L2 segment was created. Loads, which simulate the pressure from above were applied to the FEM, while a boundary condition describing the relative L1-L2 displacement is imposed on the FEM to account for 3D physiological states. The simulation calculation illustrates the stress and strain distribution and deformation of the spine. The method has two characteristics compared to previous studies: first, the finite element model of the lumbar are based on the data directly derived from medical images such as CTs and MRIs. Second, the result of analysis will be more accurate than using the data of geometric parameters. The FEM provides a promising tool in clinical diagnosis and for optimizing individual therapy in the intervertebral disc herniation.     

机动医疗系统舱室温度环境研究

目的：分析机动医疗方舱舱室温度场和气流速度场的分布状态并设计合理的舱室温度环境。方法：运用计算流体动力学理论和有限元技术建立了模拟、预测舱室温度环境的数值仿真方法，通过试验对数值仿真结果进行了验征，运用空气调节工程理论和数值仿真方法设计了医疗方舱的舱室温度环境。结果：舱室气流组织的运动形态和温度场、速度场的分布状态符合标准规定的要求。结论：数值仿真方法合理可行，设计的医疗方舱舱室温度环境有利于提高舱室内人员的热舒适性和医疗作业的效果。     

螺旋CT三维重建技术在上气道病变中的临床价值

目的　探讨螺旋CT三维(3D)重建技术在上气道病变中的临床应用价值。　方法　对36例上气道病变的患者进行轴位螺旋CT扫描,层厚3.0mm,螺距1.0～1.2,分别做气道表面遮盖法(SSD)、表面透视法(RaySum)重建和叠加成像。　结果　SSD图像能清楚显示上气道的正常形态、多方位观察可全景地反映气道表面受压的情况,RaySum能更好地显示狭窄内缘的情况,9例(25%)气道SSD显示正常;SSD图像上显示的肿瘤侵犯范围明显小于轴位和多平面重组(MPR)图像。叠加成像清楚显示肿瘤与邻近结构尤其是血管、气道的关系。　结论　3D重建能立体地显示上气道病变,是轴位和MPR图像的很好补充手段。     

Multiplanar 3D ultrasound imaging to assess the anatomy of the upper airway and measure the subglottic and tracheal diameters in adults

Objective:

To evaluate the feasibility of using three-dimensional (3D) ultrasound to assess the anatomy of the airway.

Methods:

11 young volunteers were recruited for 3D ultrasound and MRI of the airway. 3D ultrasound data were obtained from the level of the true vocal cords, cricoid cartilage and upper trachea. Multiplanar 3D ultrasound images were rendered and compared visually with corresponding MRI and cadaver anatomical sections. The anteroposterior (AP) and transverse diameter of the subglottic space and transverse diameter of the upper trachea were also measured in the 3D ultrasound and MR images and compared.

Results:

The airway anatomy was clearly delineated in the multiplanar 3D ultrasound images. It was also possible to identify the cricothyroid junction, and a simple method to measure the AP diameter of the subglottic space using this landmark is described. We were also able to accurately measure the transverse diameter of the upper trachea, but the transverse diameter of the subglottic space was overestimated using ultrasound. There was a strong correlation for the AP diameter measurement (r=0.94, p<0.05) and moderate correlation for the transverse diameter measurement (r=0.82, p=0.002) of the subglottic space, and a strong correlation for the transverse diameter measurement (r=0.91, p<0.05) of the upper trachea, in the ultrasound and MR images.

Conclusion:

The anatomy of the adult airway can be assessed using 3D ultrasound. It can also be used to accurately measure the AP diameter of the subglottic space and the transverse diameter of the upper trachea.

Advances in knowledge:

This is the first report to describe the use of 3D ultrasound to evaluate the anatomy of the upper airway and accurately measure the AP diameter of the subglottic space and the transverse diameter of the upper trachea.Ultrasound imaging of the airway has been described [1–6], but the majority of the published data involve the use of two-dimensional (2D) ultrasound, which allows examination of the airway in only the transverse or sagittal axis [2,7,8]. There is also a paucity of data correlating the sonoanatomy of the airway [2,7] with an alternative imaging modality [2]. Three-dimensional (3D) ultrasound imaging is currently available and provides simultaneous images of an area of interest (volume) in multiple orthogonal (perpendicular) planes [9]. Preliminary experience with 3D ultrasound suggests that the spatial anatomical information obtained is more detailed [9] than with 2D ultrasound, and the same may apply for imaging of the airway. Currently, there are no published data on 3D ultrasound imaging of the airway. The aim of this pilot study was to evaluate the feasibility of using 3D ultrasound to delineate the anatomy of the upper airway and correlate the sonoanatomy with cadaver anatomical sections and volunteer MR images of the airway. A secondary objective was to measure the subglottic and tracheal diameters in the multiplanar 3D ultrasound images.     

上气道螺旋CT三维重建技术及其临床应用价值

目的 探讨上气道的螺旋CT三维（3D）重建技术及其临床应用价值。材料与方法 对10例正常和36例上气道病变的患者进行轴位螺旋CT扫描,层厚3．0mm,正常组采用不同重建间隔、阈值作气道表面遮盖法（SSD）重建,病变组分别作气道SSD、Ray-Sum(表面透视法）重建和叠加成像。结果 采用1．0mm重建间隔、上层阈值为－500HU能获得最佳的气道SSD图像;SSD图像能清楚显示上气道的正常形态,多方位观察可全景地反映气道表面受压的情况,RaySum能更好地显示狭窄内缘的情况,9例（25％）病变组气道SSD显示正常;SSD图像上显示的肿瘤侵犯范围明显小于轴位和多平面重建（MPR）图像。叠加成像能清楚显示肿瘤与邻近结构尤其是血管、气道的关系。结论 3D重建能立体地显示上气道病变,是轴位和MPR图像的很好补充手段。     

Segmentation and three-dimension reconstruction of Chinese digitized human cerebrum.

OBJECTIVE: A 3D digitized visible model of human cerebrum was built to provide anatomical structure for making plans of cerebral surgical operation and realizing accurate simulation of cerebrum on computer. METHODS: Transverse sectional anatomy data of the cerebrum were chosen from the first Chinese visible human (one male and one female). Semi-automated segmentation and Photoshop software were selected to segment cerebral cortex, white matter, basal nuclei, lateral ventricle, hippocampus, etc. On personal computer, the segmented structures were reconstructed in 3D with volume rendering reconstruction and surface rendering reconstruction. RESULTS: Two accurately segmented images of the main structures of cerebrum were completed. The reconstructed structures can be displayed singly, in small groups or as a whole and can be continuously rotated in 3D space at different velocities. CONCLUSION: Combining volume-rendering reconstruction with surface rendering reconstruction overcomes the defects of surface rendering reconstruction that lack of internal anatomical information, which provides a new method for 3D reconstruction. The reconstructed cerebrum and the main internal structures are realistic, which demonstrates the natural shape and exact position of the structures. It provides an accurate model for the automated segmentation algorithmic study and provides a digitized anatomical mode of cerebrum.     

Proposal of new upper airway margins in children assessed by CBCT

Objectives:

Recently, studies have performed three-dimensional analyses of upper airways in children. However, there was a lack of airway delineation according to anatomical boundaries and/or easily mobile soft-tissue landmarks were used. The aim of the present study was to define new upper airway margins in children on CBCT according to anatomical bony landmarks and to validate the method.

Methods:

25 scans were randomly selected from a larger database containing CBCT scans of children prior to orthodontic treatment (14 girls and 11 boys; mean age, 10.9 ± 2.5 years). Scans were evaluated by two observers. Specific head positioning and virtual orientation protocols were adopted and greyscale thresholding was established for each patient. Volume and minimum cross-sectional area of the oropharynx were calculated. Intra- and interobserver reliability were assessed by reassessment of the CBCTs 2 weeks later.

Results:

The new airway margins were defined superiorly by a line passing through the palatal plane (anterior nasal spine to posterior nasal spine) extending to the posterior wall of the pharynx, inferiorly by a line passing from the anterosuperior edge of C4 to menton, anteriorly by a line passing from the soft palate to menton, posteriorly and laterally by the respective pharyngeal walls. Method error for airway volume and minimal cross-sectional area was ≤2.00%, and intra- and interobserver reliability ranged from 0.99 to 1.00.

Conclusions:

The proposed protocol utilizes easily identifiable bony landmarks to delineate the upper airway on cone beam scans of children and was found to be reliable and reproducible.     

低剂量CT扫描及定量分析对慢性阻塞性肺疾病气道病变的应用研究

目的：探讨低剂量 CT 扫描及定量分析在慢性阻塞性肺疾病(COPD)患者气道病变中的应用价值。方法122例研究对象(其中正常对照组34例,稳定期 COPD 88例)均行低剂量 CT 扫描,88例 COPD 同时行肺功能检查。采用定量 CT 气道分析软件分别测量右上叶尖段、两下叶后基底段第3级支气管气道相关参数。结果中度组、重度组及极重度组 COPD 管壁面积百分比(WA %)、气道内周径为10 mm 时的管壁厚度(hypothetical airway with internal perimeter of 10 mm,Pi10)均大于正常对照组(P 均<0.05),极重度组 COPD WA%、Pi10大于轻度组 COPD(P 均<0.05)。重度组 COPD 管壁厚度(T)与体表面积比值(T/BSA)、管壁面积与体表面积比值(WA/BSA)均大于正常对照组及中度组 COPD(P 均<0.05)。COPD WA%、Pi10分别与肺通气功能指标、小气道功能指标呈负相关(r 值范围为-0.34~-0.51,P 均<0.01),且 Pi10与肺容积指标呈正相关(r 值范围为0.32~0.33,P 均<0.05)。结论低剂量 CT 扫描定量分析可为 COPD 气道病变提供客观定量评价信息,气道参数 WA%、Pi10是2个客观评价指标;随着COPD 肺功能程度加重,支气管厚度逐渐增厚。     

多普勒血流超声医学图像的动态三维重建

目的：将超声医学图像三维重建技术与多普勒血流成像技术结合起来，实现超声血流图的动态三维重建。方法：通过对多普勒血流图的彩色编码方式的研究，利用多普勒血流图中Color Bar的信息，解决了从原始多普勒血流图中分离解剖结构和功能信息的问题，实现了心腔内血流的动态三维重建及与心脏解剖结构的三维融合显像。结果：对临床人体实验获取的超声血流图像进行三维重建，所得重建图中，血流信息与解剖结构之间的相互关系正确，与心脏解剖生理情况相符，证明了方法的可行性和有效性。结论：结合超声医学图像三维重建技术和多普勒成像技术，实现超声医学图像功能三维重建，提供更多的医学信息，是超声医学成像技术的发展方向，具有巨大的应用前景。     

A combined region growing and deformable model method for extraction of closed surfaces in 3D CT and MRI scans

Image segmentation of 3D medical images is a challenging problem with several still not totally solved practical issues, such as noise interference, variable object structures and image artifacts. This paper describes a hybrid 3D image segmentation method which combines region growing and deformable models to obtain accurate and topologically preserving surface structures of anatomical objects of interest. The proposed strategy starts by determining a rough but robust approximation of the objects using a region-growing algorithm. Then, the closed surface mesh that encloses the region is constructed and used as the initial geometry of a deformable model for the final refinement. This integrated strategy provides an alternative solution to one of the flaws of traditional deformable models, achieving good refinements of internal surfaces in few steps. Experimental segmentation results of complex anatomical structures on both simulated and real data from MRI scans are presented, and the method is assessed by comparing with standard reference segmentations of head MRI. The evaluation was mainly based on the average overlap measure, which was tested on the segmentation of white matter, corresponding to a simulated brain data set, showing excellent performance exceeding 90% accuracy. In addition, the algorithm was applied to the detection of anatomical head structures on two real MRI and one CT data set. The final reconstructions resulting from the deformable models produce high quality meshes suitable for 3D visualization and further numerical analysis. The obtained results show that the approach achieves high quality segmentations with low computational complexity.