耳蜗长度的无创伤性测量及其横断面的提取

针对耳蜗尺寸小、形状复杂的特点，给出了一种测量人类耳蜗长度的无创伤性测量方法。首先，使用三维窄带水平集算法从颞骨螺旋CT图像中分割出耳蜗。其次，采用自．动跟踪算法提取耳蜗底周质心。再次，采用人机交互的方法提取耳蜗中周、顶周部分的质心。最后，提取的耳蜗质心点之间使用Cardinal样条插值，得到光滑的耳蜗中心线，该中心线的长度即为所测耳蜗的长度。借助耳蜗中心线，还可实现沿耳蜗长度方向任一位置的垂直横断面的提取。该方法不仅可测量形状正常的耳蜗，对于耳蜗畸形的情况同样适用。应用颞骨螺旋CT数据测量的耳蜗长度与显微解剖测量结果进行了比较，无显著性差异。     

基于分水岭算法的交互式三维分割方法

背景：在临床中准确对人体组织进行三维分割能提高临床诊断的准确性,但传统的分水岭算法存在过度分割问题,难以实现人体组织的三维分割。 目的：为准确三维分割人体组织,减少图像中伪极小值点对图像分割的影响,提出了一种基于控制标记符分水岭的交互式三维分割方法。 方法：提取CT序列图像的内部和外部标记符,以此修正梯度图像并进行分割;在此基础上,根据序列图像上下层的相似性,利用人机交互进行组织结构的三维分割。首先在第一张序列图像上手工选取感兴趣区域上的一个点,借助同一组织在连续CT序列图像上面积的重叠关系即可从三维序列图上提取出感兴趣区域。 结果与结论：基于控制标记符的分水岭算法解决了直接应用梯度图像进行分割的过度分割问题,便于进一步分割图像。利用基于分水岭算法的交互式三维分割方法得到的三维分割结果经过三维可视化后可清晰、准确地反映组织的三维特征。     

基于Matlab距骨快速图像分割与动画生成的算法

背景:骨科手术导航是利用计算机和机器视觉技术,使医师在计算机屏幕的指导下完成接骨手术。为了后续定位工作的开展,首先必须基于CT图像序列在计算机上对下肢骨进行图像分割、三维重建和动画显示,并对其位姿进行测量。目的:在计算机上快速自动地实现距骨图像的分割、三维可视化及动画显示,为建立新型的足部手术导航系统搭建计算机显示平台。方法:基于足部CT图像序列,提出下列算法并采用Matlab编程实现:①基于最大熵原则对足部图像进行阈值分割以提取其中所有足部骨骼。②将形态学算法与Live-wire算法相结合快速自动地从该足部骨骼图像中分割出距骨。③利用移动立方体法对距骨表面进行三维重建。④采用图形学函数生成与显示距骨旋转的动画场景。结果与结论:实验结果表明,上述算法准确度高且以较少的时间在普通PC机上实现了距骨的三维可视化工作,可应用于足部手术导航的计算机显示平台中。     

基于CUDA的快速三维医学图像分割

目的:三维分割是医学图像分析和可视化中的重要组成部分,也是医学图像分割中的一个难点。水平集方法在三维医学图像分割中有很广阔的应用前景,但是该算法的计算量大,不能达到实时处理的要求。针对这个问题,提出了一种基于CUDA的并行加速方法。方法:采用NVIDIA公司的GPGPU模型CUDA,利用图像像素的独立性和偏微分方程求解的并发性,提高C-V水平集算法的分割速度。给出了并行计算的流程图,并对C-V水平集算法在CUDA上的实现进行了详细介绍。结果:实现了C-V水平集并行加速算法,该方法在保证分割效果的前提下,具有更快的分割速度。结论:所提出的方法是切实可行的,实现了快速的三维医学图像分割。     

基于特征和层间相关性的CTA体数据自动去骨算法

在计算机断层造影增强图像(CTA)体数据中,骨骼是血管三维可视化的重要障碍。针对CTA体数据的去骨问题,提出一种基于特征和层间相关性的CTA体数据自动去骨算法。首先,利用CTA体数据的CT值,对骨骼和血管进行粗分割;然后,利用骨骼和血管的空间形态特征,对过分割的血管区域进行还原;最后,在三维空间模式下,对残余骨骼体素和与骨骼粘连的血管区域进行特征识别和层间相关性处理,在不需要用户手动参与的情况下,实现骨骼的全自动去除。对49套CTA体数据进行实验,结果表明:该算法具有很强的鲁棒性,实现速度快,对患者的伤害小,完全满足临床诊断中的血管三维可视化要求。     

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。     

医学图像的三维重建及基于VTK的实现和应用

背景：VTK是一个免费的图像三维重建和处理的专业开发平台,其功能强大,源代码开放,用户可以根据自己的需求灵活的定制和开发。 目的：介绍图像三维可视化中常用的面绘制和体绘制两类可视化技术的原理,以及其典型的Marching Cubes和Ray Casting三维重建算法,并对重建的三维医学图像的应用和扩展进行了探讨。 方法：基于免费的VTK可视化开发包平台和Visual C++ 6.0 IDE开发工具,使用C++语言,采用真实人体CT数据集,实现CT图像的三维重建和应用扩展。 结果与结论：基于VTK平台,采用面绘制和体绘制不同绘制原理实现了医学图像的三维可视化。重建得到的三维医学图像,显示效果清晰直观,并且可以配合进行三维医学图像的测量、虚拟切割等操作,取得了较好的效果。     

结合管状特征的胆囊动脉血管分割及Calot三角三维成像

目的 探讨结合血管管状特征的胆囊动脉血管分割方法以及三维可视化胆囊三角（Calot三角）的可行性.方法 采集13例患者多层螺旋CT扫描图像,利用结合血管管状特征的三维区域生长算法,分割出胆囊动脉及与其相连的动脉血管,通过自主研发的三维重建软件CalotShow 1.0对所采集数据进行三维可视化研究.结果该方法能有效分割胆囊动脉,获得直观的Calot三角三维可视化模型.结论利用结合管状特征的胆囊动脉血管分割方法以及CalotShow1.0三维重建软件,能够准确显示胆囊动脉与Calot三角毗邻关系和空间构象.     

女性盆底可视化研究

目的：建立中国人体女性盆底部局部可视化数字模型。方法：应用中国女性数字化可视人体数据集，采用体绘制及面绘制重建方法，分别在P4微机和SGI工作站上对盆底部结构进行计算机三维重建及立体显示。结果：在P4微机上实现女性盆底部交互式三维可视化，在SGI工作站上重建了女性盆底部三维数字模型，三维重建图像能够清晰显示盆底部肌肉与骨性结构、膀胱、子宫及直肠等的三维解剖关系。结论：中国女性数字化可视人体数据集能够提供完整精确的断面数据，女性盆底三维交互可视化及数字模型准确反映该区域复杂的解剖结构及其空间毗邻关系，可为该区疾病的影像诊断及外科手术治疗提供形态学依据。     

基于冠状面数据的肝静脉和肝内门静脉的三维重建

目的:构建基于肝连续薄层冠状断面数据集的肝静脉和肝内门静脉的三维数字化可视模型。方法:应用数控冷冻铣削技术获取1例肝的连续薄层冠状断面数据集;采用体绘制和面绘制的方法,通过人工干预对数据集中肝内管道系统进行人工识别提取和图像数据分割;运用3D医学可视化软件实现三维重建,构建肝静脉和肝内门静脉的三维可视化模型。结果:肝静脉和肝内门静脉的可视化模型可清晰显示门静脉及其分支和肝静脉及其属支的空间构形,真实地再现了肝门静脉和肝静脉之间复杂的空间毗邻关系。模型中的肝静脉和肝门静脉可单独或总体显示,可在三维空间位置上绕任意轴旋转任意角度,并能从不同的角度对某一血管分支进行多角度、多方位的观察。结论:高质量的二维图像、精确的数据分割和合适的三维重建方法保证了三维数字化可视模型的真实性和准确性。     

A semiautomatic three-dimensional segmentation method for disarticulation of bone structures on spiral computed tomography images

The use of binary thresholding for segmenting bone structures on spiral computed tomography images is negatively influenced by partial volume effects (PVEs) induced by the image acquisition. PVE leads to mixed voxels, making the binary decision “bone” or “non-bone” a difficult one to take. As a result, two distinct bone structures that are close to each other will often appear to be connected by this method. A typical example consists of “acetabulum/femural head” pairs in the pelvic region. To separate them, a clinical user must interactively draw a disarticulation line. This procedure is time consuming (often interaction in 50 slices is needed) and leads to unsmooth visualization of the disarticulated areas (by three-dimensional [3D] rendering techniques). We developed a semiautomatic cutting algorithm that leads to smooth disarticulated surfaces and considerably decreases the amount of user interaction. A sheet detection operator is applied to automatically separate bone structures. Detected sheets are used as disarticulation lines. Postprocessing ensures that sheets not relevant for the application do not influence the resulting image. Our approach is encapsulated in an interactive segmentation environment based on thresholding and 3D connected-component labeling. Results are shown for pelvic region, wrist, and foot bone disarticulations.     

三维医学图像的交互式图形处理器快速重建

目的:开发一种基于图形处理器(GPU)的医学三维图像交互式重建系统,用于临床辅助诊断、手术计划等领域。方法:在GPU重建算法基础上使用了八叉树空间结构和多边形辅助光线投射方法实现进一步的优化,分别用基础算法和优化后的算法对一组CT图像进行重建,验证优化效果。结果:本研究实现的优化算法在真实医学三维图像重建中得到了高质量的重建结果,并且比原有的基于GPU的重建算法快2～3倍。结论:本研究实现的三维重建系统能有效加快重建速度,实现交互式快速重建。     

数字人体断层彩色图像数据的真实感体绘制

目的　探索一种用于数字人体断层彩色图像数据的真实感三维重建方法。  方法　改进光线投射体绘制算法,将真实的颜色采样和传递函数颜色映射相结合,使其适应彩色数据;使用分割标记数据,为多重组织彩色数据分类,实现数字人体断层彩色图像的直接体绘制。  结果　此方法实现了数字人体复杂组织和器官的高度真实感三维重建。  结论　断层彩色图像数据的真实感体绘制,能准确反映数字人体结构的细节和颜色信息,得到边界清晰的三维模型。     

用Shear-warp算法实现超声心脏图像的快速体绘制

Shear- warp是基于物体空间扫描的一种体绘制技术 ,与传统的体绘制法相比 ,具有速度快、图像质量高的特点。本文介绍了 Shear- warp算法的原理 ,并将该算法应用到旋转扫描超声心脏图像插值结果的可视化 ,实现了心脏三维解剖结构的快速、准确重建。该算法在医学图像可视化中有广阔的应用前景     

A fast way to visualize the brain surface with volume rendering of MRI data

The preprocessing of 3-dimensional (3D) MRI data constitutes a bottleneck in the process of visualizing the brain surface with volume rendering. As a fast way to achieve this preprocessing, the authors propose a simple pipeline based on an algorithm of seed-growing type, for approximate segmentation of the intradural space in T1-weighted 3D MRI data. Except for the setting of a seed and four parameters, this pipeline proceeds in an unsupervised manner; no interactive intermediate step is involved. It was tested with 15 datasets from normal adults. The result was reproducible in that as long as the seed was located within the cerebral white matter, identical segmentation was achieved for each dataset. Although the pipeline ran with gross segmentation error along the floor of the cranial cavity, it performed well along the cranial vault so that subsequent volume rendering permitted the observation of the sulco-gyral pattern over cerebral convexities. Use of this pipeline followed by volume rendering is a handy approach to the visualization of the brain surface from 3D MRI data.     

A detailed 3D model of the guinea pig cochlea

Several partial models of cochlear subparts are available. However, a complete 3D model of an intact cochlea based on actual histological sections has not been reported. Hence, the aim of this study was to develop a novel 3D model of the guinea pig cochlea and conduct post-processes on this reconstructed model. We used a combination of histochemical processing and the method of acquiring section data from the visible human project (VHP) to obtain a set of ideal raw images of cochlear sections. After semi-automatic registration and accurate manual segmentation with professional image processing software, one set of aligned data and six sets of segmented data were generated. Finally, the segmented structures were reconstructed by 3D Slicer (a professional imaging process and analysis tool). Further, post-processes including 3D visualization and a virtual endoscope were completed to improve visualization and simulate the course of the cochlear implant through the scala tympani. The 3D cochlea model contains the main six structures: (1) the inner wall, (2) modiolus and spiral lamina, (3) cochlea nerve and spiral ganglion, (4) spiral ligament and inferior wall of cochlear duct, (5) Reissner’s membrane and (6) tectorial membrane. Based on the results, we concluded that ideal raw images of cochlear sections can be acquired by combining the processes of conventional histochemistry and photographing while slicing. After several vital image processing and analysis steps, this could further generate a vivid 3D model of the intact cochlea complete with internal details. This novel 3D model has great potential in teaching, basic medical research and in several clinical applications. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

2D/3D registration of endoscopic ultrasound to CT volume data

This paper describes a computer-aided navigation system using image fusion to support endoscopic interventions such as the accurate collection of biopsy specimens. An endoscope provides the physician with real-time ultrasound (US) and a video image. An image slice that corresponds to the corresponding image from the US scan head is derived from a preoperative computed tomography (CT) or magnetic resonance image volume data set using oblique reformatting and displayed side by side with the US image. The position of the image acquired by the US scan head is determined by a miniaturized electromagnetic tracking system (EMTS) after calibrating the endoscope's scan head. The transformation between the patient coordinate system and the preoperative data set is calculated using a 2D/3D registration. This is achieved by calibrating an intraoperative interventional CT slice with an optical tracking system (OTS) using the same algorithm as for the US calibration. The slice is then used for 2D/3D registration with the coordinate system of the preoperative volume. The fiducial registration error (FRE) for the US calibration was 2.0 mm +/- 0.4 mm; the interventional CT FRE was 0.36 +/- 0.12 mm; and the 2D/3D registration target registration error (TRE) was 1.8 +/- 0.3 mm. The point-to-point registration between the OTS and the EMTS had an FRE of 0.9 +/- 0.4 mm. Finally, we found an overall TRE for the complete system to be 3.9 +/- 0.6 mm.     

Assessment of Real-Time 3D Visualization for Cardiothoracic Diagnostic Evaluation and Surgery Planning

Rationale and Objectives Rationale and Objectives: Three-dimensional (3D) real-time volume rendering has demonstrated improvements in clinical care for several areas of radiological imaging. We test whether advanced real-time rendering techniques combined with an effective user interface will allow radiologists and surgeons to improve their performance for cardiothoracic surgery planning and diagnostic evaluation.Material and Methods Materials and Methods: An interactive combination 3D and 2D visualization system developed at the University of North Carolina at Chapel Hill was compared against standard tiled 2D slice presentation on a viewbox. The system was evaluated for 23 complex cardiothoracic computed tomographic (CT) cases including heart–lung and lung transplantation, tumor resection, airway stent placement, repair of congenital heart defects, aortic aneurysm repair, and resection of pulmonary arteriovenous malformation. Radiologists and surgeons recorded their impressions with and without the use of the interactive visualization system.Results Results: The cardiothoracic surgeons reported positive benefits to using the 3D visualizations. The addition of the 3D visualization changed the surgical plan (65% of cases), increased the surgeons confidence (on average 40% per case), and correlated well with the anatomy found at surgery (95% of cases). The radiologists reported fewer and less major changes than the surgeons in their understanding of the case due to the 3D visualization. They found new findings or additional information about existing findings in 66% of the cases; however, they changed their radiology report in only 14% of the cases.Conclusion Conclusion: With the appropriate choice of 3D real-time volume rendering and a well-designed user interface, both surgeons and radiologists benefit from viewing an interactive 3D visualization in addition to 2D images for surgery planning and diagnostic evaluation of complex cardiothoracic cases. This study finds that 3D visualization is especially helpful to the surgeon in understanding the case, and in communicating and planning the surgery. These results suggest that including real-time 3D visualization would be of clinical benefit for complex cardiothoracic CT cases.Supported in part by NIH RO1-CA 44060, NIH PO1-CA 47982, and NIH RO1-CA 60193.