虚拟内窥镜的发展和应用

虚拟内窥镜是一种新的非侵一诊断方法，它使用计算机处理ＣＴ和ＭＲＩ等三维图像，生成人体内部物质壹解剖结构的三维动态视图，以模拟标准内窥镜的检查过程和视效果。它具有非侵入性、重复使用、动态病理分析、无检查死区等独特优点，具有广泛的应用前景为此许多国家和研究机构都投入了大量的人力物力进行研究。     

虚拟内窥镜的发展和应用

虚拟内窥镜是一种新的非侵入性诊断方法，它使用计算机处理ＣＴ和ＭＲＩ等三维医学图像，生成人体内部特定解剖结构的三维动态视图，以模拟标准内窥镜的检查过程和视觉效果。它具有非侵入性、重复使用、动态病理分析、无检查死区等独特优点，具有广泛的应用前景，为此许多国家和研究机构都投入了大量的人力物力进行研究。     

虚拟内窥镜系统中表面法向量的计算

表面法向量计算是虚拟内窥镜系统中的一个重要问题，通常采用距离梯度法和密度梯度法计算。作对这两种方法的优缺点作了讨论，针对它们彼此具有互补的特点，提出将距离梯度图像和密度梯度图像相融合的方法，并分别设计了代数融合和几何融合两种方法。实验结果显示，融合后的图像质量有了明显改善，而且几何融合法优于代数融合法。     

交互式虚拟内窥镜成像及应用

目的：作为虚拟内窥镜系统开发的基础性课题,本文针对虚拟内窥镜研究中交互式成像问题展开研究,以求得快速而优质的成像效果。方法：首先提出一种简单直观的坐标变换方法,便于进行交互式的虚拟内窥镜成像。其次,为解决交互式虚拟内窥镜成像的速度问题,使用精简后的光线投射法进行体绘制重建,在使其能够在保证一定图像精度的同时提高速度。结果：实验得到了满意的交互式成像效果。结论：所提出的方法是切实可行的,从而为进一步开发高精度的交互式虚拟内窥镜系统打下了坚实的基础。     

虚拟三维人体解剖学展示系统的设计

背景：应用计算机虚拟技术配合双向交互式人机界面,设立虚拟实验室,使抛弃面对面教学成为了可能。 目的：使用虚拟三维技术实现人体解剖学标本演示,在清晰度、质感、素材输入难易度上全面超越常规三维建模方法制作的电子标本,最终实现远程教育网上虚拟解剖实验室的应用。 方法：自行开发半自动控制的三维标本数据录入硬件系统,全方位的录入解剖标本、模型的素材资料,形成资料库。用软件系统虚拟三维展示解剖标本、模型,并提供相关文献资料、语音解说等素材。 结果与结论：完成了三维标本数据录入机的制作,可以在5 min内将一个实体标本转化为数字化图像数据,数据无需处理,直接输入数据库即可通过虚拟三维演示系统实现远程标本立体显示。三维动画相对于传统二维图片,具有立体,直观,使用方便,不会损耗,易于扩展等优点,在人体解剖的教学及医学科普教育上有良好的应用前景。     

多层CT虚拟血管内窥镜指导腹主动脉瘤支架植入

据Sun Z[J Vasec Interv Radiol,2004，15(9）：961-970]报道，采用层厚2mm、螺距1和重建间隔1mm的成像方案，虚拟血管内窥镜(VIE)成像指导主动脉支架植入术，很少出现梯度伪影，可观察主动脉支架。     

多层CT虚拟血管内窥镜指导腹主动脉瘤支架植入

据Sun Z[J Vasc Interv Radiol，2004，15(9)：961—970]报道，采用层厚2mm、螺距1和重建间隔1mm的成像方案，重建主动脉支架植入图像，几乎无梯度伪影，可观察主动脉支架线。     

磁场方式的内窥镜体内三维定位与追踪方法研究

本研究以磁场方式来测定内窥镜探头在人体内的三维位置及姿态角。根据三个互相正交的圆环线圈在其周围空间任意点产生的三维磁感应强度表达式 ,以及附着于内窥镜探头上的三个相互正交的磁场传感器在该磁场空间任意点以任意姿态感应磁场时所获得信号的表达式 ,建立以空间位置 (x ,y ,z) ,姿态角 (a ,b ,c)为未知数的六元非线性方程组。使用具有全局收敛特性的牛顿 拉夫森算法求解非线性方程组 ,由磁场传感器所获得的测量数据计算出对应的一组位置和姿态 (x ,y ,z ,a ,b,c) ,从而实现内窥镜探头的三维定位和跟踪     

虚拟内窥镜图像增强膝关节镜手术导航系统

膝关节镜手术是利用内窥镜的膝关节微创手术,具有创口小、恢复快等优势,但同时整个手术仅凭术中二维膝关节镜图像引导,存在缺乏深度信息、容易出现遮挡、依赖手术经验等缺点。利用虚拟内窥镜技术,将术前与术中的信息结合,互为补充,为膝关节镜手术进行导航,增加其便利性和可靠性。提出基于虚拟内窥镜技术的膝关节镜手术导航系统:首先通过对内窥镜及整个坐标系统的标定,完成对整个系统的坐标描述;然后针对实时追踪的内窥镜视角,实现对应范围术前信息的渲染,最后将术前术中及融合信息通过二维、三维显示方式,全面地展示给医师。完成系统的搭建及完整的膝关节模型实验,将术前术中信息同时显示、精确融合,实现导航功能;实验的定位标定均方误差小于1 mm,术前术中图像融合匹配均方误差小于0.7 mm,分立及融合图像均可实时显示。综合定位信息与术前信息的膝关节镜手术导航系统,可以实时进行内窥镜图像增强,为膝关节镜术提供多源信息融合引导,为医生提供直观、便捷的手术导航效果。     

虚拟心脏搭桥手术模型雕塑系统的研究

目的利用力反馈装置在虚拟三维环境中实现抓取和变形等操作,模拟心血管手术中的血管搭桥术式。方法利用医院中真实病人的CT扫描数字图片重建出心脏可视化模型并进行显示,建立搭桥血管,然后利用力反馈装置对血管模型进行雕塑,以模拟Fontan手术中从肺动脉到右心室的血管搭桥手术。结果在虚拟三维环境中显示心脏的空间结构,选择任意长度和直径的血管进行虚拟搭桥仿真,或选择自定义大小的补片对模型进行修补,最终得到术后模型和测量参数。结论力反馈装置在虚拟心脏搭桥手术中的应用为今后模拟各种手术术式、建立包含力学特性的手术规划系统奠定了基础。     

Comparing 3D Virtual Methods for Hemimandibular Body Reconstruction

Reconstruction of fractured, distorted, or missing parts in human skeleton presents an equal challenge in the fields of paleoanthropology, bioarcheology, forensics, and medicine. This is particularly important within the disciplines such as orthodontics and surgery, when dealing with mandibular defects due to tumors, developmental abnormalities, or trauma. In such cases, proper restorations of both form (for esthetic purposes) and function (restoration of articulation, occlusion, and mastication) are required. Several digital approaches based on three‐dimensional (3D) digital modeling, computer‐aided design (CAD)/computer‐aided manufacturing techniques, and more recently geometric morphometric methods have been used to solve this problem. Nevertheless, comparisons among their outcomes are rarely provided. In this contribution, three methods for hemimandibular body reconstruction have been tested. Two bone defects were virtually simulated in a 3D digital model of a human hemimandible. Accordingly, 3D digital scaffolds were obtained using the mirror copy of the unaffected hemimandible (Method 1), the thin plate spline (TPS) interpolation (Method 2), and the combination between TPS and CAD techniques (Method 3). The mirror copy of the unaffected hemimandible does not provide a suitable solution for bone restoration. The combination between TPS interpolation and CAD techniques (Method 3) produces an almost perfect‐fitting 3D digital model that can be used for biocompatible custom‐made scaffolds generated by rapid prototyping technologies. Anat Rec, 2011. © 2011 Wiley‐Liss, Inc.     

Diagnostic Contribution of Virtual Endoscopy in Diseases of the Upper Airways

Purpose Virtual endoscopy (VE) is a new diagnostic tool that generates 3-dimensional (3D) views of a lumen by exploiting cross-sectional images. The purpose of this study was to evaluate the usefulness of VE as a diagnostic tool in the diseases of the larynx and pharynx. Materials and Methods Twenty-two patients with a mean age of 57 years were included in the study. The patients underwent larynx examination, optical endoscopy (OE), and computed tomography (CT) of the larynx. Later, VE was produced from the CT images. Results Eight patients had larynx carcinoma, a 5-year-old patient had a laryngeal web, a 43-year-old man had fish bone stuck in his submucosal layer, 10 patients were normal, and the remaining two patients were under follow-up for treated nasopharynx carcinoma and had no evidence for recurrence. VE showed the laryngeal tumor in seven patients and the laryngeal web in one patient, but failed to show a plaquelike tumor and the fishbone within the submucosa. Conclusions Our findings suggest that VE is a useful and complimentary method of 3D imaging in the diseases compromising the laryngeal lumen. Furthermore, it may be superior to OE in severe stenosis or obstructions where the endoscope cannot be passed through.     

Improvements in education in pathology: Virtual 3D specimens

Virtual three-dimensional (3D) specimens correspond to 3D visualizations of real pathological specimens on a computer display. We describe a simple method for the digitalization of such specimens from high-quality digital images. The images were taken during a whole rotation of a specimen, and merged together into a JPEG2000 multi-document file. The files were made available in the internet (http://patho.med.uni-magdeburg.de/research.shtml) and obtained very positive ratings by medical students. Virtual 3D specimens expand the application of digital techniques in pathology, and will contribute significantly to the successful introduction of knowledge databases and electronic learning platforms.     

虚拟内窥镜关键技术的研究与临床应用

研究虚拟内窥镜的关键技术,并以临床试验加以验证.对不同的临床CT资料,使用研发关键技术后的虚拟内窥镜系统进行内窥镜临床试验.结果证明,采用该技术开发虚拟内窥镜系统符合临床应用要求.本文所采用的技术是可行的.     

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。     

Virtual 3D microscopy using multiplane whole slide images in diagnostic pathology

To reproduce focusing in virtual microscopy, it is necessary to construct 3-dimensional (3D) virtual slides composed of whole slide images with different focuses. As focusing is frequently used for the assessment of Helicobacter pylori colonization in diagnostic pathology, we prepared virtual 3D slides with up to 9 focus planes from 144 gastric biopsy specimens with or without H pylori gastritis. The biopsy specimens were diagnosed in a blinded manner by 3 pathologists according to the updated Sydney classification using conventional microscopy, virtual microscopy with a single focus plane, and virtual 3D microscopy with 5 and 9 focus planes enabling virtual focusing. Regarding the classification of H pylori, we found a positive correlation between the number of focus planes used in virtual microscopy and the number of correct diagnoses as determined by conventional microscopy. Concerning H pylori positivity, the specificity and sensitivity of virtual 3D microscopy using virtual slides with 9 focus planes achieved a minimum of 0.95 each, which was approximately the same as in conventional microscopy. We consider virtual 3D microscopy appropriate for primary diagnosis of H pylori gastritis and equivalent to conventional microscopy.     

基于冠状动脉造影图像序列的心脏三维运动模型

本研究提出了一种根据单面冠状动脉造影图像序列分析心脏三维运动的算法。根据心脏运动的先验知识，建立了包含心脏主要运动形式的运动模型，按照从整体到局部的顺序，将心脏的复杂运动分解为整体刚性运动、整体变形以及局部运动和变形，并估计其参数。利用估计出来的各运动组成部分的参数，得到对心脏运动的量化描述。     

基于Opengl|ES的心脏模型三维显示技术研究

为改进当前医疗电子仪器的显示效果,本研究在嵌入式系统中实现三维显示功能。先用Rhino建立心脏模型,再在Embedded Visual C环境中应用Opengl｜ES API等编写应用程序进行三维显示。结果表明：程序可在目标机上流畅运行,所显示的模型比较逼真,可对模型进行任意角度的旋转、设置颜色等操作。嵌入式系统在三维显示技术中的应用具有较大发展空间,在医疗电子仪器领域应用价值较大。