基于高精度断层图片数据集的大鼠动脉血管重建

目的基于微米级大鼠断层图片数据集,建立高精度的大鼠动脉血管的三维模型,为各种监测鼠血管组织形态变化的试验提供客观依据。方法采用一套高分辨率大鼠断层切片图像数据集,使用半自动交互方法对动脉血管进行分割,使用改进的移动立方体(marching cube,MC)算法,在一台IBM图形工作站上对80 GByte大小的血管图片数据集进行重建。结果建立了完整的高精度大鼠动脉血管的三维表面模型,能显示出0.4mm大小的微细血管。结论该大鼠动脉血管三维模型可以为观测试验鼠血管组织形态变化提供一个立体的空间比较标准。     

数字虚拟中国人男性一号循环系统的三维建模

目的建立虚拟中国人男性一号血管灌注循环系统的三维模型,为解剖教学以及临床虚拟手术研究提供三维数据模型。方法对数字虚拟中国人男性一号样本进行血管灌注,对获取的彩色断层图片进行空间配准和半自动交互分割,对分割后的数据通过并行算法进行快速三维重建处理。结果对灌注后的动静脉血管和心脏建立了三维模型;通过组合动脉和静脉以及心脏模型获得了全身循环系统的三维模型,弥补了数字化虚拟人体血管模型的空白。结论经过样本的动脉灌注处理之后,在获取高分辨率的切片数据的基础上,建立了精确、完整的血管模型。     

基于"中国数字人"切片和CT数据重建下颌骨的对比研究

目的：探索快速重建人体下颌骨三维模型的方法，比较常用CT资料重建与切片资料重建骨组织的优劣差异。方法：获得虚拟人数据集，并取虚拟人数据中下颌骨部分的切片资料和CT资料分别进行软件的三维重建。结果：利用切片资料建立了较之CT资料更为精细准确的人体下颌骨三维模型。结论：采用应用软件重建方法快速可行，而且利用虚拟人的切片数据建立了高度精确的下颌骨三维模型。     

数字化虚拟中国人女性一号数据图像处理

目的：运用数字化虚拟中国人女性一号数据集，测试图像处理软件对数据集进行三维重建、图像分割及有限元建模效果的可行性。方法：利用等问距抽取、格式转换、图像分割、三维重建、三维显示及有限元建模等方法对虚拟中国人女性一号(VCH—F1)部分数据集进行实验研究。结果：编辑了几种数据版本；实现了图像分割；重构了冠状面图像及矢状面图像；将静态显示制成动画；实现了实时三维显示；建立了基于CT图像的局部有限元模型。结论：虚拟人体女性一号数据集的不同压缩、格式转换能满足形态学三维重建、图像分割、实时三维显示的要求；CT、MRI和切削图像分割重建的骨骼模型可进行有限元建模研究。     

儿童肝超薄铣削断层解剖及可视化重建

目的：了解儿童肝胆系统形态结构、走行规律，辨清儿童及成人肝的差异，为编写儿童解剖图谱提供素材，丰富对儿童肝胆系统的认识。方法 ：选取男童标本1具，利用数控冷冻铣削技术，采用从足到头逐层超薄铣切，进行数字儿童肝胆系统图像手动分割，分割提取后将数据导入Digihuman Reconstruction System，并建立三维模型，将初步建立的模型进行微调和修改。采用描述法对重建后的儿童三维肝胆系统模型进行显示。结果 ：获得肝连续薄层解剖断面图像1 234张，获得了儿童三维肝胆系统及儿童断层解剖图谱。结论 ：通过对肝断层解剖结构的分析与处理，可以立体地展示肝胆系统的解剖关系；三维图像可形象、动态地显示肝胆系统的解剖特点。     

基于MRI切片的人体复杂结构的三维建模方法

目的：探讨使用Mimics软件构建包含皮肤、肌肉、脂肪以及骨骼的复杂三维人体模型的方法及意义。方法：利用MRJ（MagneticResonanceImaging）切片通过MIMICS软件分别建立人体骨骼、肌肉、脂肪、皮肤等几何面模型，准确表达人体组织和器官的复杂几何结构；将组织和器官的几何面模型导入到MAGICS中进行面网格划分，通过ANSYS软件将面网格转化为体网格，得到人体各器官和组织的三维几何体模型；进而给骨骼、肌肉、脂肪、皮肤分别赋予材料特性（弹性模量和泊松比等），可以模拟真实人体组织和器官的物理属性。结果：利用MIMICS的布尔运算将各部分组织和器官进行组装，得到人体复杂结构的三维实体模型。结论：与目前常用的基于几何学的人体模型建模方法相比，使用该方法建立的三维实体模型可以完全模拟人体器官和组织的真实结构，等效程度高、建模速度快。所建立的数学模型可以直接用于3D打印、模具制造及等效假人的运动学和力学分析。广泛应用于医学、人机工程学等领域。     

三维可视化系统对髋关节骨性结构的评价

背景：目前通过二维断层图像信息来判断病变组织的具体性状其难度仍然较大,而运用医学三维重建技术,将能够显著改善医务工作者对相关疾病诊断的工作效率和准确率。 目的：开发一套医学三维可视系统,能够通过读取髋关节DICOM数据重建相应部位三维模型,并通过重建模型直观观察病变髋关节的形态。 方法：使用个人电脑在WindowsXP操作系统,开发环境为VC++6.0,安装VTK 5.6并进行必要设置,使用MFC开发一套医学三维可视化系统,具体步骤如下：①创建一个绘制对象。②创建一个绘制窗,将绘制对象加入绘制窗口。③读取CT图像序列,设置读取图像序列的路径。④使用MC算法抽取等值面(生成三角面片),根据灰度的不同,分别从切片数据中提取出皮肤和骨骼。设置输入图像序列数据;设置抽取的组织轮廓线灰度值。⑤建立三角带对象和数据映射对象。⑥实现图形的绘制,接收几何数据的属性,并分别对骨骼和皮肤设置不同的颜色和透明度。⑦设置视角位置,观察对象位置和焦点。⑧创建人机交互功能。 结果与结论：使用VC++6.0及VTK可以满足医学三维可视系统开发的需求,开发的三维可视系统软件能通过对髋关节DICOM格式的CT图像序列进行三维重建,重建的髋关节三维模型可以使用旋转、缩放、平移来直观的观察髋关节的骨性结构,骨折形态及类型,对相关治疗及手术有一定参考作用。中国组织工程研究杂志出版内容重点：人工关节;骨植入物;脊柱;骨折;内固定;数字化骨科;组织工程全文链接：     

基于冷冻切片的人体腰椎三维有限元模型

目的利用上海交通大学生命质量与机械工程研究所自主开发的冷冻切片处理软件CryoSegmemation提取人体骨骼的边缘,利用逆向工程软件Imageware建立骨骼的面模型,在ANSYS中建立人体腰椎的三维有限元模型。方法利用第三军医大学的第一例男性冷冻切片数据进行图像处理,截面轮廓线信息处理。结果准确快速地建立了完全符合人体解剖特征的腰椎三维有限元模型。结论利用该研究所自主开发的冷冻切片软件和一些现有的商用软件可以准确、快速地建立人体腰椎的三维面模型、体模型及有限元模型,为航空、车辆、船舶、生物医学工程等不同的领域进行数值模拟计算和动力学仿真提供完全符合人体解剖学特征的原始模型。     

人体CT切片图像中骨骼的分割

在实现人体骨骼的三维可视化中 ,首要的一步是将骨骼从二维图像中分割出来。本研究选用美国国家医学图书馆提供的可视人体项目中 1733张女性 CT切片数据 ,提出了一套图像去噪、分割和平滑的处理方法。在去噪中使用了 Chebyshev一致逼近滤波技术 ;在分割中提出了一种简单实用的自适应阈值法 ,将图像之间的相关性与区域生长法结合 ;后处理中使用形态学方法、多分辨率滤波等算法。完成了对所有 1733张图片的分割 ,经过与原图的对照 ,证明了所提出方法在分割中的准确性和较广泛的适用性     

基于关节坐标系的肌肉骨骼间附着点坐标转换方法

目的运动状态下对人体骨肌系统进行运动学及动力学分析时,应避免对人体造成伤害。本研究通过尸体切片、CT或者MRI图像重建等方法构建静态骨肌模型,并将其应用于活体进行分析。方法采用尸体切片数据重建下肢的三维骨肌模型,并对此骨肌模型及活体下肢建立统一规则的关节坐标系,详细描述人体骨肌系统模型和活体上相关肌肉骨骼间附着点空间坐标值转换。结果对研究对象膝关节屈曲运动中股二头肌短头力臂及长度进行计算和分析。结论该方法对提高人体运动学和动力学仿真及肌肉力预测具有重要意义。     

采用体绘制方法建立人股骨三维有限元模型及其应力分析

背景：目前股骨三维有限元研究建模方法有多种,而采用体绘制分体建模方法还未曾报道过。 目的：采用体绘制方法建立股骨三维有限元实体模型,对所建实体模型模拟力学载荷得出股骨应力分布,并与既往股骨力学实验比较,评估体绘制方法的可行性。 方法：将CT扫描图像去噪等预处理后,采用体绘制技术,利用Mimics和Ansys软件建立人股骨有限元模型,并在Mimics软件中赋予股骨材质,并模拟人体正常站立位时股骨载荷情况。 结果与结论：采用体绘制方法建立的人股骨三维有限元模型,包括皮质骨、松质骨及髓腔解剖结构,网格化后共生成63 900个节点,43 552个实体单元;模拟载荷显示股骨压应力区域主要集中在股骨内侧、尤其是股骨距部位,张应力主要集中于股骨颈外侧、股骨干外侧。表明体绘制方法可以建立高仿真、接近股骨解剖结构股骨三维有限元模型实体模型,可以探索股骨的内部结构,展现其内部细节,模拟股骨生物力学分布。关键词：体绘制;股骨;实体模型;有限元;力学分布 doi:10.3969/j.issn.1673-8225.2012.17.003     

A synchrotron radiation microtomography system for the analysis of trabecular bone samples.

X-ray computed microtomography is particularly well suited for studying trabecular bone architecture, which requires three-dimensional (3-D) images with high spatial resolution. For this purpose, we describe a three-dimensional computed microtomography (microCT) system using synchrotron radiation, developed at ESRF. Since synchrotron radiation provides a monochromatic and high photon flux x-ray beam, it allows high resolution and a high signal-to-noise ratio imaging. The principle of the system is based on truly three-dimensional parallel tomographic acquisition. It uses a two-dimensional (2-D) CCD-based detector to record 2-D radiographs of the transmitted beam through the sample under different angles of view. The 3-D tomographic reconstruction, performed by an exact 3-D filtered backprojection algorithm, yields 3-D images with cubic voxels. The spatial resolution of the detector was experimentally measured. For the application to bone investigation, the voxel size was set to 6.65 microm, and the experimental spatial resolution was found to be 11 microm. The reconstructed linear attenuation coefficient was calibrated from hydroxyapatite phantoms. Image processing tools are being developed to extract structural parameters quantifying trabecular bone architecture from the 3-D microCT images. First results on human trabecular bone samples are presented.     

Localization of cochlear implant electrodes in radiographs

Multielectrode cochlear implantation is the most effective treatment for profound sensorineural hearing loss. In vivo three-dimensional 3-D localization of cochlear implant electrodes is important for modeling of the electrical field in the cochlea, design of electrode arrays, and may improve speech processor programming for better speech recognition. The prerequisite for 3-D localization of the electrodes is their 2-D localization in x-ray radiographs. In this paper, we develop a practical method to localize the electrodes with high efficiency, accuracy, and reproducibility. In this method, a priori knowledge of the electrodes and their approximate positions are utilized, an intelligent thresholding and segmentation mechanism is embedded, and the electrode center is computed as the weighted geometric center of segmented electrode pixels. Experiments with physical phantoms and human data demonstrate the feasibility and utility of this method. The PC-based program developed for this project is disseminated on the Web.     

基于Visualization Toolkit的数字化人体骨骼系统的重建与可视化

在人体骨骼系统的三维可视化过程中,将二维CT数据重建生成理想的三维骨骼数据是非常重要的一环.作者应用可视化工具Visualization Toolkit(VTK)和VC++实现了二维数据的三维重建、面片削减、连通性检测、三维平滑等一系列功能.与利用OpenGL等工具重建得到的骨骼数据相比,不但准确度和视觉效果有了显著改善,数据量也大大减小.VTK在人体骨骼系统的重建及处理工作中取得的良好效果表明,它是医学图像重建和处理的有力工具之一,具有使用灵活,功能强大的优点,值得推广.     

上颌骨种植体与天然牙三维有限元模型的建立

探讨获得种植体与天然牙在上颌骨复合体三维影像以建立三维有限元模型的方法。采用螺旋CT断层扫描技术,数字影像与转录技术,自编程序与ANSYS软件相结合,将CT扫描图像转换为可用于有限元建模的数值图像。结果表明:三维有限元实体模型与螺旋CT三维重建影像比较,几何相似性与还原性良好,材料构造合理。说明采用螺旋CT扫描技术及ANSYS软件,建立上颌骨种植体模型切实可行,结果令人满意。     

Human graft cornea and laser incisions imaging with micrometer scale resolution full-field optical coherence tomography

Micrometer scale resolution full-field optical coherence tomography (FF-OCT) is developed for imaging human graft corneas. Three-dimensional (3-D) images with ultrahigh resolution (respectively, 1 and 1.5 μm in the axial and transverse directions), comparable to traditional histological sections, are obtained allowing the visualization of the cells and the precise structure of the different layers that compose the tissue. The sensitivity of our device enables imaging the entire thickness of the cornea, even in edematous corneas more than 800 μm thick. Furthermore, we provide tomographic 3-D images of laser incisions inside the tissue at various depths without slicing the studied corneas. The effects of laser ablations can be observed, along various optical sections, directly in the bulk of the sample with high accuracy, providing information on the interface quality and also imaging tiny changes of the tissue structure. FF-OCT appears to be a powerful tool for subcellular imaging of the corneal structure and pathologies on the entire thickness of the tissue as well as interface quality and changes in the collagen structure due to laser incisions on ex vivo human cornea.     

Evaluation of segmented 3D acquisition schemes for whole‐brain high‐resolution arterial spin labeling at 3 T

Recent technical developments have significantly increased the signal‐to‐noise ratio (SNR) of arterial spin labeled (ASL) perfusion MRI. Despite this, typical ASL acquisitions still employ large voxel sizes. The purpose of this work was to implement and evaluate two ASL sequences optimized for whole‐brain high‐resolution perfusion imaging, combining pseudo‐continuous ASL (pCASL), background suppression (BS) and 3D segmented readouts, with different in‐plane k‐space trajectories. Identical labeling and BS pulses were implemented for both sequences. Two segmented 3D readout schemes with different in‐plane trajectories were compared: Cartesian (3D GRASE) and spiral (3D RARE Stack‐Of‐Spirals). High‐resolution perfusion images (2 × 2 × 4 mm³) were acquired in 15 young healthy volunteers with the two ASL sequences at 3 T. The quality of the perfusion maps was evaluated in terms of SNR and gray‐to‐white matter contrast. Point‐spread‐function simulations were carried out to assess the impact of readout differences on the effective resolution. The combination of pCASL, in‐plane segmented 3D readouts and BS provided high‐SNR high‐resolution ASL perfusion images of the whole brain. Although both sequences produced excellent image quality, the 3D RARE Stack‐Of‐Spirals readout yielded higher temporal and spatial SNR than 3D GRASE (spatial SNR = 8.5 ± 2.8 and 3.7 ± 1.4; temporal SNR = 27.4 ± 12.5 and 15.6 ± 7.6, respectively) and decreased through‐plane blurring due to its inherent oversampling of the central k‐space region, its reduced effective T_E and shorter total readout time, at the expense of a slight increase in the effective in‐plane voxel size. Copyright © 2014 John Wiley & Sons, Ltd.     

Three-dimensional biodegradable microscaffolding: scaffold characterization and cell population at single cell resolution

Engineering artificial tissue scaffolds with a similar organization to that of the natural tissue is a key element to the successful recapitulation of function. However, three-dimensional (3-D) fabrication of tissue scaffolds containing complex microarchitectures still remains a challenge. In addition, little attention has been paid to the issue of how to incorporate cells within 3-D tissue scaffolds that contain precisely engineered architectures. Here we report a 3-D biodegradable microscaffolding (3D-BMS) technology and its process characterization as well as a microscale cellular loading technology as an efficient way to massively populate biodegradable polymers with cells at single cell resolution. In this study a particular emphasis was given to characterization of the material properties of the biodegradable polymers undergoing the 3D-BMS processes. Optimal process conditions were identified in order to avoid any unwanted change in material properties, such as crystallinity and scaffold strength, that have a direct impact on the degradation speed and physical integrity of the constructed scaffolds. For precise control of the cell distribution within the microstructured scaffolds a high precision microsieve structure was designed to localize rat hepatocytes and human articular chondrocytes in the biodegradable polymers. Cell suspensions were passed at a predetermined flow rate through biodegradable polymer layers that contained tapered microholes in a massively parallel process. This high resolution cell seeding method allows accurate manipulation of cell placement in thin layers of biodegradable polymers.     

Anatomical education and surgical simulation based on the Chinese Visible Human: a three-dimensional virtual model of the larynx region

Anatomical knowledge of the larynx region is critical for understanding laryngeal disease and performing required interventions. Virtual reality is a useful method for surgical education and simulation. Here, we assembled segmented cross-section slices of the larynx region from the Chinese Visible Human dataset. The laryngeal structures were precisely segmented manually as 2D images, then reconstructed and displayed as 3D images in the virtual reality Dextrobeam system. Using visualization and interaction with the virtual reality modeling language model, a digital laryngeal anatomy instruction was constructed using HTML and JavaScript languages. The volume larynx models can thus display an arbitrary section of the model and provide a virtual dissection function. This networked teaching system of the digital laryngeal anatomy can be read remotely, displayed locally, and manipulated interactively.