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1.
基于多层Mumford-Shah向量值图像分割、去噪与重建模型(HMSMv)和光滑样条曲线拟合技术,提出了一种用于计算机辅助青光眼诊断的视乳头图像视杯和视盘重建、分割与度量的新方法。首先,采用HMSMv分割和重建视杯和视盘;然后,基于重建的视乳头图像,结合青光眼视乳头图像杯、盘的先验知识,提取视杯和视盘特征矩形和边缘特征点;最后,采用光滑样条曲线拟合技术,重建被血管遮挡的视杯和视盘部分边缘,并计算杯盘比等病理特征参数值。不同青光眼病人的视乳头图像杯盘重建、分割与度量实验结果表明,该方法能克服噪声污染、血管遮挡、光照不均匀、对比度小、个体间差异大等视网膜图像分割中固有的困难,并有效重建、分割与度量青光眼彩色视乳头图像中的视杯和视盘。  相似文献   

2.
提出一种基于灰度积分投影与模糊C均值聚类的肺实质分割算法,用于CT图像的快速自动分割。首先,对原始肺部CT图像分别在水平和垂直方向上进行灰度积分投影;然后,选用平滑样条曲线拟合平滑原始图像的积分投影曲线,并提取拟合平滑前后曲线的极大值点,确定肺实质初始边界;最后,利用模糊C均值聚类算法对边界内区域进行分割,结合滚动小球法修复边界区域,获得肺实质区域。选取LIDC(肺部图像数据库联盟)数据库中20组图像(平均每组图像包含120幅CT图像)进行实验,平均分割精度为95.66%,平均每幅图像花费时间为0.77s。实验结果表明,该方法可以用于CT图像肺实质分割,具有全自动、高精度、鲁棒性等特点。  相似文献   

3.
牙颌CT图像序列中牙的半自动分割方法   总被引:2,自引:0,他引:2  
牙颌CT图像序列相邻切片之间,相应牙的大小、位置以及牙区域和轮廓的灰度分布等特征比较接近,并呈一定的变化规律,根据这一特点提出了牙颌CT图像序列中牙的半自动分割方法。首先选取参考切片,加入少量用户操作进行参考切片中牙轮廓的提取,接着以参考切片为起始切片,由已完成轮廓提取的牙包围盒作为待处理切片(相邻切片)相应牙的操作区间,然后在此区间内用区域生长法提取牙轮廓,由此逐张切片处理可以自动地得到所有切片全牙列每颗牙的轮廓。实验结果表明,本方法仅需少量用户交互就能快速、基本准确地从牙颌CT图像序列中分割出牙轮廓,具有一定的实用价值。  相似文献   

4.
在牙种植技术中,牙齿特征点的有效提取对后续的三维配准和重建具有重要的意义,现有方法的计算效率比较低;论文改进了离散曲线演化算法,采用曲线特征因子量描述牙齿CT各断层图像边缘曲线的复杂性,并根据曲线特征因子量自适应确定不同层间图像边缘曲线特征点提取的数目,以降低数据存储的冗余量,提高特征点的提取效率;用改进的离散曲线演化算法对牙齿不同层的临床CT图像提取特征点,并将实验结果与现有离散曲线演化算法的结果进行比较。结果表明,改进方法在提取每层CT图像特征点所需时间约为原算法的50%,同时提取的特征点数约为原算法的80%。将改进方法提取的特征点按不同比率进行三次样条曲线插值并进行后期重建,其重建效果能很好地反映牙齿的真实结构。因此,改进方法的计算效率远高于离散曲线演化算法,在牙齿种植领域中具有临床应用前景。  相似文献   

5.
虚拟中国人女性一号松质骨图像数据的配准与三维重建   总被引:9,自引:0,他引:9  
目的:研究从虚拟人体数据集中松质骨连续切片图像的分割、配准、及三维重建的技术方法。方法:利用现有的虚拟中国人女性一号数据集中腰椎和股骨部分解剖连续切片数据集,用基于外置标记点和分割—计数法两种方法进行参数计算,依参数对图像进行刚体变换完成配准,将配准后的切片图像输入二维图像处理软件进行分割,提取感兴趣区域后输入三维重建软件进行三维重建。结果:重建后的松质骨三维立体图像呈均匀、致密的立体网状结构,骨小梁连接清晰可见。结论:利用现有软件及技术可重建虚拟人体的精细结构。  相似文献   

6.
基于肺部CT序列图像的肺实质三维分割   总被引:3,自引:1,他引:2  
目的:肺实质分割是基于CT图像的肺结节计算机辅助检测技术必不可少的步骤。结合阈值技术、连通区域标记以及形态学技术,提出了一种简单有效的从CT图像中分割三维肺实质的方法,以期能为后续肺结节计算机辅助检测技术的研究奠定基础。方法:首先,将原图像二值化,并应用三维连通域标记去除背景及细小空洞;然后,经三维区域生长法去除气管;最后,经形态学滤波平滑肺边界得到肺部精确的三维模板,并采用该模板从CT序列图像中分割出肺实质。结果:根据对20组层厚2.0mm、每组约250个切片的肺部CT临床数据实验验证,其肺实质分割的平均正确度为91.55%,处理单组数据平均耗时167.4563s。结论:实验结果表明,本文方法能自动快速地从CT序列图像中分割出肺实质。  相似文献   

7.
在肾脏组织切片图像的自动分析系统中,肾小球区域边界的增强是一个关键的环节。肾组织切片图像的复杂特点导致了对肾小球边界特征描述的困难。本文在给出特殊边界定义下提出了一种特征模板,用神经元网络构造非线性阈值曲面,考虑网络容错性对边界增强效果的影响,选择合适的阈值曲面进行边界增强。实验结果表明,该容错学习可以在抑制噪声的同时获得对肾小球边界的增强,从而获得良好的处理效果,并且对染色程度不同的样本图像具有强的适应性。  相似文献   

8.
大鼠松质骨切片图像的三维重建与定量分析   总被引:3,自引:0,他引:3  
本文研究动物松质骨连续切片图像数据集的获取、分割、配准、及三维重建的技术方法.利用病理切片和图像数码摄入技术,获取了大鼠腰椎松质骨连续切片图像数据集,用基于外置标记点和分割-计数法两种方法进行参数计算,依参数对图像进行刚体变换完成配准,将配准后的切片图像输入二维图像处理软件进行分割,提取感兴趣区域后输入三维重建软件进行三维重建与定量分析.重建后的松质骨三维立体图像呈均匀、致密的立体网状结构,骨小梁连接清晰可见.  相似文献   

9.
目的 利用三维重建工具软件对小鼠大脑、海马结构进行三维重建,并对重建的图像进行观察和测量。 方法 获取小鼠大脑连续冷冻Nissl染色切片,进行图像预处理后,构建三维重建数据集。利用PhotoshopCS3软件对小鼠大脑冠状切片海马结构的不同区域填充不同的颜色。然后,利用3DDOCTOR 4.0软件分别对上述连续切片图像进行配准、分割和三维重建,并对重建的脑及海马结构进行观察。 结果 利用小鼠脑连续冷冻Nissl染色切片图像可以对小鼠海马结构进行三维重建,并能立体观察海马下托、CA1、CA2、CA3、CA4区和齿状回等结构。 结论 利用小鼠脑的连续冷冻Nissl染色切片可以对小鼠脑及海马结构进行三维重建。  相似文献   

10.
大鼠肾标本连续切片的三维重建及形态学测量   总被引:1,自引:1,他引:0  
目的 综合运用目前较成熟的技术,建立一个易施行的、可对大组织标本连续切片整体图像进行三维重建及形态学测量的方法。 方法 对正常大鼠肾的石蜡包埋标本进行全序列连续切片,HE染色后对切片图像进行数字化采集,经过拼接、配准步骤,建立切片整体图像的数字化数据集,对其内部的血管系统及肾盂进行分割及三维重建,并对重建结果进行形态学测量。 结果 切片的整体图像清晰,数字化图像数据集配准准确,三维重建结果再现了各种结构的立体特征及其在原组织块内的位置,在三维空间内,可进行无阻挡的自由观察,并且测量出了脉管系统的多项三维形态学指标,包括组织体积构成百分比、动脉长度及分支角度等。 结论 采用这种方法取得了较为满意的重建结果,可为其他组织连续切片的三维重建研究提供借鉴。  相似文献   

11.
目的探索基于系列磁共振图像获取鼻腔边界的有效分割方法.对图像进行准确分割并考察鼻腔的解剖结构。方法受试者为健康男性,年龄24岁。采用层间距为4mm的冠状面头颈部MRI图像.用MATLAB编程对图像预处理。使用距离正则化水平集图像分割方法分割鼻腔的边界.并借助插值算法计算任意位置的鼻腔横截面积.以及通过对横截面积分布曲线的积分算出鼻腔体积。结果精确分割出鼻腔边界,获得其坐标,并可保存为图像格式或数据文件格式。给出左、右鼻腔横截面积随距离变化的连续分布曲线、鼻腔最小截面的位置.以及鼻腔体积。结论该方法可以有效地分割出几何形态复杂的鼻腔的边界并获得鼻腔的结构参数数值.所得到的边界坐标数据可方便地用于鼻腔结构的三维重建。  相似文献   

12.
Recent advances in physical models of skeletal dosimetry utilize high-resolution 3-dimensional microscopic computed tomography images of trabecular spongiosa. These images are coupled to radiation transport codes to assess energy deposition within active bone marrow and trabecular endosteum. These transport codes rely primarily on the segmentation of the spongiosa images into bone and marrow voxels. Image thresholding has been the segmentation of choice for bone sample images because of its extreme simplicity. However, the ability of the segmentation to reproduce the physical boundary between bone and marrow depends on the selection of the threshold value. Statistical models, as well as visual inspection of the image, have been employed extensively to determine the correct threshold. Both techniques are affected by partial volume effect and can provide unexpected results if performed without care. In this study, we propose a new technique to threshold trabecular spongiosa images based on visual inspection of the image gradient magnitude. We first show that the gradient magnitude of the image reaches a maximum along a surface that remains almost independent of partial volume effect and that is a good representation of the physical boundary between bone and marrow. A computer program was then developed to allow a user to compare the position of the iso-surface produced by a threshold with the gradient magnitude. The threshold that produces the iso-surface that best coincides with the maximum gradient is chosen. The technique was finally tested with a set of images of a true bone sample with different resolutions, as well as with three images of a cube of Duocell aluminium foam of known mass and density. Both tests demonstrate the ability of the gradient magnitude technique to retrieve sample volumes or media volume fractions with 1% accuracy at 30 microm voxel size.  相似文献   

13.
Boundary extraction of carpal bone images is a critical operation of the automatic bone age assessment system, since the contrast between the bony structure and soft tissue are very poor. In this paper, we present an edge following technique for boundary extraction in carpal bone images and apply it to assess bone age in young children. Our proposed technique can detect the boundaries of carpal bones in X-ray images by using the information from the vector image model and the edge map. Feature analysis of the carpal bones can reveal the important information for bone age assessment. Five features for bone age assessment are calculated from the boundary extraction result of each carpal bone. All features are taken as input into the support vector regression (SVR) that assesses the bone age. We compare the SVR with the neural network regression (NNR). We use 180 images of carpal bone from a digital hand atlas to assess the bone age of young children from 0 to 6 years old. Leave-one-out cross validation is used for testing the efficiency of the techniques. The opinions of the skilled radiologists provided in the atlas are used as the ground truth in bone age assessment. The SVR is able to provide more accurate bone age assessment results than the NNR. The experimental results from SVR are very close to the bone age assessment by skilled radiologists.  相似文献   

14.
Swensson RG  King JL  Gur D 《Medical physics》2001,28(8):1597-1609
We propose a principled formulation of the ROC curve that is constrained in a realistic way by the mechanism of probability summation. The constrained and conventional ROC formulations were fitted to 150 separate sets of rating data taken from previous observer studies of 250 or 529 chest radiographs. A total of 20 different readers had used either discrete or continuous rating scales to evaluate those chest cases for likelihood of separate specified abnormalities: interstitial disease, pulmonary nodule, pneumothorax, alveolar infiltrate, or rib fracture. Both ROC formulations were fitted separately to every set of rating data using maximum-likelihood statistical procedures that specified each ROC curve by normally distributed latent variables with two scaling parameters, and estimated the area below the ROC curve (Az) with its standard error. The conventional and constrained binormal formulations usually fitted ROC curves that were nearly indistinguishable in form and in Az. But when fitted to asymmetric rating data that contained few false-positive cases, the conventional ROC curves often rose steeply, then flattened and extrapolated into an unrealistic upward "hook" at the higher false-positive rates. For those sets of rating data, the constrained ROC curves (without hooks) estimated larger values for Az with smaller standard errors. The constrained ROC formulation describes observers' ratings of cases at least as well as the conventional ROC, and always guarantees a realistic fitted curve for observer performance. Its estimated parameters are easy to interpret, and may also be used to predict observer accuracy in localizing the image abnormalities.  相似文献   

15.
基于CAD软件的髋臼骨形态三维结构重建   总被引:2,自引:1,他引:1  
目的利用髋臼轮廓的三维数据值重建髋臼骨形态,并能对其解剖结构进行定量测量。方法选取成人髋臼标本,通过CT扫描、图像边界处理和定标,利用CAD软件直接拟合出髋臼骨形态。结果重建的髋臼能客观反映髋臼真实解剖形态。结论以CT二维图像为依据,采用CAD软件,能准确地进行髋臼的重建,为髋臼的形态学研究提供了一种可行的方法。  相似文献   

16.
OBJECTIVE: To determine the effect of degraded digital image resolution (as viewed on a monitor) on the accuracy and confidence of dermatologic interpretation. MATERIALS AND METHODS: Eight dermatologists interpreted 180 clinical cases divided into three Logical Competitor Sets (LCS) (pigmented lesions, non-pigmented lesions, and inflammatory dermatoses). Each case was digitized at three different resolutions. The images were randomized and divided into (9) 60-image sessions. The physicians were completely blinded concerning the image resolution. After 60 seconds per image, the viewer recorded a diagnosis and level of confidence. The resultant ROC curves compared the effect of LCS, level of clinical difficulty, and resolution of the digital image. One-way analysis of variance (ANOVA) compared the curves. RESULTS: The areas beneath the ROC curves did not demonstrate any consistently significant difference between the digital image resolutions for all LCS and levels of difficulty. The only significant effect observed was amongst pigmented lesions (LCS-A) where the ROC curve area was significantly smaller in the easy images at high resolution compared to low and medium resolutions. For all other ROC curve comparisons within LCS-A, at all other levels of difficulty, as well as within the other LCS at all levels of difficulty, none of the differences was significant. CONCLUSION: A 720 x 500 pixel image can be considered equivalent to a 1490 x 1000 pixel image for most store-and-forward teledermatology consultations.  相似文献   

17.
从心脏PET或SPECT图像中提取完整的心肌区域是定量分析心功能的前提。心脏的PET和SPECT图像边界模糊,在病理状态下可能有局部显像缺失,致使图像分割困难。本研究提出一种基于医学知识的快速推进法,利用拟合的椭球模型将边界演化推进到局部低显像区,从而分割出一个完整的左心室心肌区域。实验图像测试和实际图像分割表明这种算法对于有显像缺失的三维核医学心脏图像的分割是有效的。  相似文献   

18.
Magnetic Resonance Imaging (MRI) longitudinal studies conducted to assess changes in tibia bone quality impose strict requirements on the reproducibility of the prescribed region acquired. Registration, the process of aligning two images, is commonly performed on the images after acquisition. However, techniques to improve image registration precision by adjusting scanning parameters prospectively, prior to image acquisition, would be preferred. We have adapted an automatic prospective mutual information based registration algorithm to a MRI longitudinal study of trabecular bone of the tibia and compared it to a post-scan manual registration. Qualitatively, image alignment due to the prospective registration is shown in 2D subtraction images and 3D surface renderings. Quantitatively, the registration performance is demonstrated by calculating the sum of the squares of the subtraction images. Results show that the sum of the squares is lower for the follow up images with prospective registration by an average of 19.37% ± 0.07 compared to follow up images with post-scan manual registration. Our study found no significant difference between the trabecular bone structure parameters calculated from the post-scan manual registration and the prospective registration images (p > 0.05). All coefficient of variation values for all trabecular bone structure parameters were within a 2–4.5% range which are within values previously reported in the literature. Results suggest that this algorithm is robust enough to be used in different musculoskeletal imaging applications including the hip as well as the tibia.  相似文献   

19.
瓣后血流湍流剪应力在体无创测量技术   总被引:1,自引:0,他引:1  
本文提出并实现了基于彩色超声多普勒速度图像分析的瓣后血流湍流剪应力的在体无创测量的数值方法及软件。首先通过图像处理和图像分析得到待测位点至少5个心动周期的速度曲线,然后在每个周期获取该位点N(N≥5)个时刻的瞬时速度信息,由此计算该位点的速度扰动并进一步计算法向雷诺应力和湍流剪应力。软件包括图像捕获、图像预处理、交互式速度获取以及湍流剪应力计算等功能,并使用了多媒体数据库对数据和图像进行管理。实际应用表明,该方法和软件是一种方便可行的在体无创测量瓣后血流湍流剪应力的手段,可为一些瓣膜疾病的诊断和人工心瓣的性能评估提供有效的血液动力学依据。  相似文献   

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