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。     

基于虚拟中国人数据集的鼻部及颞骨解剖结构三维重建

目的：为可视化虚拟人体模型鼻部及颞骨解剖结构的三维重建探索一种可行的方法。方法：利用3D-Slicer软件进行鼻部及颞骨部分解剖结构的三维重建。对单层图片进行图象分割及提取，处理后的体数据导入3D—Slicer，选择阈值进行进一步的图像分割，产生感兴趣区的标志图，进而重建出组织结构的三维表面模型。结果：成功重建了四组鼻窦，鼻中隔，中下鼻甲，颞骨，鼓室，乳突气房，乙状窦，颈内动脉的三维表面模型，并可显示不同结构间的毗邻关系与空间定位。结论：基于中国第一号虚拟人数据集，用3—D软件可以实现鼻部颞骨部分解剖结构三维可视化，便于对该部解剖结构的观察和理解。     

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。     

基于CT数据的医学图像处理系统设计

基于医学DICOM序列图像数据,利用Insight Segmentation and Registration Toolkit和Visualization Toolkit工具包对图像数据进行处理,实现图像的读取、滤波和调窗等预处理。对不同目标区域分别采用区域生长法和水平集法进行分割,实现面绘制的体素级重建方法绘制和体绘制的光线投影法绘制,构建出目标模型的三维模型。以QT和VS2013为平台,设计图像处理系统,完成图像的读取、预处理、二维分割、三维重建和人机交互等功能。系统可提供方便、快捷的操作,构建逼真的三维模型,对目标区域准确定位、快速诊断,提高医护人员的工作效率。     

基于区域生长法的三维心血管模型的分割

目的医学图像能够反映人体各组织的生理或病理性的结构信息和功能信息,根据图像序列,对患者心血管组织进行三维重建,可以方便医生对血管的病灶部位做出准确诊断。本文将区域生长法(region growing method,RGM)在二维图像的基础上用于三维,并比较RGM的3种子方法对心血管模型进行三维分割的效果。方法结合VTK(Visualization Toolkit)与ITK(Insight Segmentation and Registration Toolkit)函式库,首先利用光线投射法(ray casting,RC)对患者的CT扫描图像序列进行三维重建,得到患者胸腔三维模型;之后分别利用区域生长法中连通阈值、置信连接和邻域连接3种算法进行三维分割处理,得到患者心血管模型的仿真结果。结果三维重建仿真技术,具有直观重现心血管造影序列所描述的人体胸腔部位各组织的可能性;3种分割算法的比较显示,邻域连接法相比于其他两种算法,模型的解剖结构信息丢失程度较大,血管树的分支数目及管径也明显偏小。结论使用VTK与ITK函式库,通过光线投射法的体绘制技术和区域生长法的图像分割技术,可以建立患者的心血管模型;区域生长法中的连通阈值和置信连接算法,对结果的细节保留程度最大。     

中国数字人数据集三维重建的方法学研究

目的：探索适合于中国数字人数据集特点的图像配准，彩色图像分割以及三维重建方法。方法：首先基于中国数字人连续断层图像的4个定位杆坐标值，对断层图像进行射影变换，消除其射影失真。纠正失真后再将断层图像根据第一个定位杆的质心坐标值裁剪成大小一致的断层图像。其次使用photoshop中knockout滤镜，完成断层图像的分割。最后使用mimics软件完成三维重建。结果：建立了中国数字人女1号髋部骨骼肌精确的三维模型。结论：髋部骨骼肌模型的三维交互可视化可以准确反映该区域复杂的解剖结构及其空间毗邻关系，同时为数字人三维可视化提供了一种精确快速的方法。     

神经元干细胞序列图像中分裂子细胞的精确分割算法

针对神经元干细胞序列图像中存在的细胞分裂现象,为了实现对于分裂子细胞的特征提取、识别和跟踪,对于分裂出的微小目标--子细胞,提出了一种能够精确保留其形状特征的分割算法.采用了基于最大熵的模糊阅值分割方法,应用遗传算法确定最大模糊熵准则下的最优参数.利用加权距离变换、区域标注和形态学运算,实现了对分割结果中的干扰区域的吞没,以及对于分割图中欠分割目标的分离.仿真结果通过与硬分割比较,表明该算法在序列图像的追踪处理中对于需要特征提取的特定目标,能够实现最大限度保留该目标形状特征的精确分割.     

血管图像分割技术的研究进展

血管图像分割是循环系统血管分析的一个重要组成部分,也是血管三维重建、定量分析的基础.本文对适于血管图像分割的区域生长法、活动轮廓模型、基于追踪的方法等传统的分割技术,及基于数学形态学、神经网络等近年来结合特定理论和工具提出的分割算法进行了综述.针对血管图像的这一具体应用领域,把现有的血管图像分割技术分成如下三类:①基于边界的分割技术;②基于区域的分割技术;③基于特定理论和工具的分割技术.     

基于双源CT图像的冠状动脉分割

背景：在计算机辅助下,从双源CT图像中把三维冠状动脉分割出来能为其定量评价提供基础。但冠状动脉的三维形态复杂多变,且其管径细小,因而实现冠状动脉的高精度分割是一项有挑战性的课题。 目的：解决冠状动脉难以实现高精度分割的问题。 方法：采用三步数据处理策略实现冠状动脉分割。先采用阈值方法对三维双源CT图像进行预分割;然后,采用交互式的策略分割出与主动脉相连的左、右冠状动脉始端;最后,根据冠状动脉始端的位置,利用形态学方法和三维断层图像相邻层间的关系分割出三维冠状动脉。 结果与结论：提出的基于形态学与断层图像层间关系的分割方法能较精确地从双源CT图像中分割出左、右冠状动脉,说明该方法适用于三维冠状动脉的分割。     

基于改进GVF-测地线模型的颈动脉斑块的分割算法

为了在超声波图像中提取颈动脉斑块边缘,我们提出了一种基于GVF-测地线模型的图像分割算法.由于超声波图像含有大量噪声,首先使用加权均值空间平滑滤波器对图像进行预处理;再人工画出初始轮廓,分别采用GVF-Snake模型、GVF-测地线模型和改进后的GVF-测地线模型对图像进行分割,比较其结果.实验结果表明,改进后的方法分割精度很高,能够在颈动脉斑块边缘提取中取得非常好的效果.     

Radial 3D TOF和常规3D TOF在颈动脉成像中的对比

目的:探讨Radial 3D Time of Flight（TOF）序列在颈动脉磁共振血管成像中的应用。方法:选取行颈动脉常规3D TOF和Radial 3D TOF的36例患者的图像资料，采用配对样本t检验对比两个序列颈动脉的信噪比、对比噪声比，采用非参数配对Wilcoxon符号秩检验对比两个序列颈动脉血管的显示效果（主观评分）。结果:Radial 3D TOF的信噪比和对比噪声比均高于常规3D TOF（t=25.7、14.2, P值均小于0.05）；血管的显示效果也优于常规3D TOF（z=-4.36, P<0.05）。结论:相比于常规3D TOF，Radial 3D TOF可以获得更好的颈动脉图像质量。     

A non-invasive study of alterations of the carotid artery with age using ultrasound images

A region-based method for measurement of arterial diameter to find out the elasticity of the vessel is proposed in this paper. Arterial segments are studied by using images obtained through ultrasound scanning in B-mode. Pulsatile changes of the common carotid artery during diastole and systole are computed. To achieve this, thinned segmentation is done by suitably adjusting the contrast of the image. The diameter changes of the artery wall from the centre of artery are calculated. Fifty-three normal subjects with age group 20–40 years are taken for measurement. Measured diameter is plotted as a graph and pulsatile changes of the artery are obtained. Since no atherosclerotic lesions are detected in the studied subjects, it is suggested that the common carotid artery is a highly compliant artery with a strong alteration of viscoelastic properties with age.     

A review of ultrasound common carotid artery image and video segmentation techniques

The determination of the wall thickness [intima–media thickness (IMT)], the delineation of the atherosclerotic carotid plaque, the measurement of the diameter in the common carotid artery (CCA), as well as the grading of its stenosis are important for the evaluation of the atherosclerosis disease. All these measurements are also considered to be significant markers for the clinical evaluation of the risk of stroke. A number of CCA segmentation techniques have been proposed in the last few years either for the segmentation of the intima–media complex (IMC), the lumen of the CCA, or for the atherosclerotic carotid plaque from ultrasound images or videos of the CCA. The present review study proposes and discusses the methods and systems introduced so far in the literature for performing automated or semi-automated segmentation in ultrasound images or videos of the CCA. These are based on edge detection, active contours, level sets, dynamic programming, local statistics, Hough transform, statistical modeling, neural networks, and an integration of the above methods. Furthermore, the performance of these systems is evaluated and discussed based on various evaluation metrics. We finally propose the best performing method that can be used for the segmentation of the IMC and the atherosclerotic carotid plaque in ultrasound images and videos. We end the present review study with a discussion of the different image and video CCA segmentation techniques, future perspectives, and further extension of these techniques to ultrasound video segmentation and wall tracking of the CCA. Future work on the segmentation of the CCA will be focused on the development of integrated segmentation systems for the complete segmentation of the CCA as well as the segmentation and motion analysis of the plaque and or the IMC from ultrasound video sequences of the CCA. These systems will improve the evaluation, follow up, and treatment of patients affected by advanced atherosclerosis disease conditions.     

CT增强扫描图像椎动脉和颈内动脉的三维重建研究

目的:探讨CT增强扫描图像在椎动脉、颈内动脉3D可视化技术中的应用。方法:1例经CT增强连续扫描检查的成人患者数据集,应用Mimics8.11对图像血管进行分割,三维重建椎动脉、颈内动脉颅内段数字图像。结果:椎动脉、颈内动脉颅内段三维重建数字图像清晰,能够准确的3D显示该血管解剖形态结构及其在颈椎、颅骨内的位置和毗邻关系。结论:三维重建图像可以提供复杂血管动态解剖,为临床诊断提供了直观的、数字化解剖参考。     

Segmentation of carotid artery in ultrasound images: method development and evaluation technique

Segmentation of carotid artery lumen in two-dimensional and three-dimensional ultrasonography is an important step in computerized evaluation of arterial disease severity and in finding vulnerable atherosclerotic plaques susceptible to rupture causing stroke. Because of the complexity of anatomical structures, noise as well as the requirement of accurate segmentation, interactions are necessary between observers and the computer segmentation process. In this paper a segmentation process is described based on the deformable model method with only one seed point to guide the initialization of the deformable model for each lumen cross section. With one seed, the initial contour of the deformable model is generated using the entropy map of the original image and mathematical morphology operations. The deformable model is driven to fit the lumen contour by an internal force and an external force that are calculated, respectively, with geometrical properties of deformed contour and with the image gray level features. The evaluation methodology using distance-based and area-based metrics is introduced in this paper. A contour probability distribution (CPD) method for calculating distance-based metrics is introduced. The CPD is obtained by generating contours of the lumen using a set of possible seed locations. The mean contour can be compared to a manual outlined contour to provide accuracy metrics. The variance computed from the CPD can provide metrics of local and global variability. These metrics provide a complete performance evaluation of an interactive segmentation algorithm and a means for comparing different algorithm settings.     

Objective characterization of the course of the parasellar internal carotid artery using mathematical tools

BACKGROUND: Along the internal carotid artery (ICA), atherosclerotic plaques are often located in its cavernous sinus (parasellar) segments (pICA). Studies indicate that the incidence of pre-atherosclerotic lesions is linked with the complexity of the pICA; however, the pICA shape was never objectively characterized. Our study aims at providing objective mathematical characterizations of the pICA shape. METHODS AND RESULTS: Three-dimensional (3D) computer models, reconstructed from contrast enhanced computed tomography (CT) data of 30 randomly selected patients (60 pICAs) were analyzed with modern visualization software and new mathematical algorithms. As objective measures for the pICA shape complexity, we provide calculations of curvature energy, torsion energy, and total complexity of 3D skeletons of the pICA lumen. We further measured the posterior knee of the so-called "carotid siphon" with a virtual goniometer and performed correlations between the objective mathematical calculations and the subjective angle measurements. CONCLUSIONS: Firstly, our study provides mathematical characterizations of the pICA shape, which can serve as objective reference data for analyzing connections between pICA shape complexity and vascular diseases. Secondly, we provide an objective method for creating such data. Thirdly, we evaluate the usefulness of subjective goniometric measurements of the angle of the posterior knee of the carotid siphon.     

Comprehensive data visualization for high resolution endovascular carotid arterial wall imaging

Carotid angioplasty and stenting is a minimally invasive endovascular procedure that may benefit from in vivo high resolution imaging for monitoring the physical placement of the stent and potential complications. The purpose of this pilot study was to evaluate the ability of optical coherence tomography to construct high resolution 2D and 3D images of stenting in porcine carotid artery. Four Yorkshire pigs were anaesthetized and catheterized. A state-of-the-art optical coherence tomography (OCT) system and an automated injector were used to obtain both healthy and stented porcine carotid artery images. Data obtained were then processed for visualization. The state-of-the-art OCT system was able to capture high resolution images of both healthy and stented carotid arteries. High quality 3D images of healthy and stented carotid arteries were constructed, clearly depicting vessel wall morphological features, stent apposition and thrombus formation over the inserted stent. The results demonstrate that OCT can be used to generate high quality 3D images of carotid arterial stents for accurate diagnosis of stent apposition and complications under appropriate imaging conditions.     

Quality evaluation of ultrasound imaging in the carotid artery based on normalization and speckle reduction filtering

Image quality is important when evaluating ultrasound images of the carotid for the assessment of the degree of atherosclerotic disease, or when transferring images through a telemedicine channel, and/or in other image processing tasks. The objective of this study was to investigate the usefulness of image quality evaluation based on image quality metrics and visual perception, in ultrasound imaging of the carotid artery after normalization and speckle reduction filtering. Image quality was evaluated based on statistical and texture features, image quality evaluation metrics, and visual perception evaluation made by two experts. These were computed on 80 longitudinal ultrasound images of the carotid bifurcation recorded from two different ultrasound scanners, the HDI ATL-3000 and the HDI ATL-5000 scanner, before (NF) and after (DS) speckle reduction filtering, after normalization (N), and after normalization and speckle reduction filtering (NDS). The results of this study showed that: (1) the normalized speckle reduction, NDS, images were rated visually better on both scanners; (2) the NDS images showed better statistical and texture analysis results on both scanners; (3) better image quality evaluation results were obtained between the original (NF) and normalized (N) images, i.e. NF–N, for both scanners, followed by the NF–DS images for the ATL HDI-5000 scanner and the NF–DS on the HDI ATL-3000 scanner; (4) the ATL HDI-5000 scanner images have considerable higher entropy than the ATL HDI-3000 scanner and thus more information content. However, based on the visual evaluation by the two experts, both scanners were rated similarly. The above findings are also in agreement with the visual perception evaluation, carried out by the two vascular experts. The results of this study showed that ultrasound image normalization and speckle reduction filtering are important preprocessing steps favoring image quality, and should be further investigated.     

A novel segmentation method using multiresolution analysis with 3D visualization for X-ray coronary angiogram images

Coronary angiography is a widely used tool in the diagnosis and treatment of cardiac diseases. The main cause of coronary artery disease is atherosclerosis, which leads to the narrowing of artery lumen, resulting in decreased blood supply to heart muscles. Determination of narrowing of the lumens mainly depends upon the quality of the segmented image; with improved segmentation technique there is better accuracy in identification of blocks. The main purpose of the paper is to develop an automatic, accurate segmentation technique with 3D visualization for the segmented images. 3D visualization provides clearer information regarding the shape and severity of the lesion. The thresholding technique is one of the oldest and simplest techniques used for segmentation. This paper proposes a multithresholding approach using the entropy measure and multiresolution analysis to ensure automatic and accurate segmentation by overcoming some of the problems encountered in other techniques. Also, segmentation performance analysis was conducted for various segmentation methods. This method is tested with different real coronary angiographic images and was found to perform better than the other techniques.     

A novel segmentation method using multiresolution analysis with 3D visualization for X-ray coronary angiogram images

Coronary angiography is a widely used tool in the diagnosis and treatment of cardiac diseases. The main cause of coronary artery disease is atherosclerosis, which leads to the narrowing of artery lumen, resulting in decreased blood supply to heart muscles. Determination of narrowing of the lumens mainly depends upon the quality of the segmented image; with improved segmentation technique there is better accuracy in identification of blocks. The main purpose of the paper is to develop an automatic, accurate segmentation technique with 3D visualization for the segmented images. 3D visualization provides clearer information regarding the shape and severity of the lesion. The thresholding technique is one of the oldest and simplest techniques used for segmentation. This paper proposes a multithresholding approach using the entropy measure and multiresolution analysis to ensure automatic and accurate segmentation by overcoming some of the problems encountered in other techniques. Also, segmentation performance analysis was conducted for various segmentation methods. This method is tested with different real coronary angiographic images and was found to perform better than the other techniques.