多普勒血流超声医学图像的动态三维重建

目的将超声医学图像三维重建技术与多普勒血流成像技术结合起来,实现超声血流图的动态三维重建. 方法通过对多普勒血流图的彩色编码方式的研究,利用多普勒血流图中Color Bar的信息,解决了从原始多普勒血流图中分离解剖结构和功能信息的问题,实现了心腔内血流的动态三维重建及与心脏解剖结构的三维融合显像. 结果对临床人体实验获取的超声血流图像进行三维重建,所得重建图中血流信息与解剖结构之间的相互关系正确,与心脏解剖生理情况相符,证明了方法的可行性和有效性. 结论结合超声医学图像三维重建技术和多普勒成像技术,实现超声医学图像功能三维重建,提供更多的医学信息,是超声医学成像技术的发展方向,具有巨大的应用前景.     

基于彩色图像分割的左心血流多普勒影像提取

目的:保存提取出的彩色血流多普勒信号,使其脱离心脏解剖结构单独显示,为与磁共振心脏融合影像奠定基础.材料和方法:利用Matlab平台对彩超仪产生的左心血流多普勒图像进行图像分割.结果:通过编程,对血流多普勒影像进行分割和后处理,使其从二维超声图像中成功分离,单独显示.结果以AVI视频格式和JPG图片格式保存[1].结论:分割后的彩色多普勒图像可以提供更多信息细节,通过Matlab进行像素信息量化,数据分析等图像后处理,获得更多血流动力学信息.在影像融合方面,通过在MRI或CT的心腔解剖结构中叠加提取的多普勒血流图像并制作成AVI视频文件,以全新的视角观察心内结构及血流,为影像学诊断提供新的参考手段.     

超声检查胎儿严重先天性心脏畸形12例漏诊及误诊的分析

目的:探讨超声筛查胎儿心脏及大动脉异常的检出率和诊断率的有效方法及注意事项。方法:应用二维超声图像对胎儿心脏进行四腔切面、左室流出道、右室流出道切面等心脏解剖结构检查,再用彩色多普勒血流图对胎儿心脏进行血流方向及速度的观察。结果:12例严重先天心脏畸形,其中误诊8例,漏诊4例。结论:超声医生对先天性心脏病知识的系统学习是提高筛查质量的关键。     

实时超声弹性成像技术在乳腺良恶性疾病鉴别诊断中的应用

超声技术在乳腺疾病的诊断中发挥着越来越重要的作用,常规二维超声,彩色多普勒及脉冲多普勒能在对病灶大小,位置,边缘情况,内部回声,血流情况,阻力指数等方面提供很多重要信息。随着医学领域对生物体的组织弹性和超弹性特性的关注,在传统二维超声成像基础上同时使用结合了组织弹性自相关方法的超声弹性成像技术,使组织的质地差异通过超声图像表现出来。该项技术能够获得常规超声所不能探测到的组织弹性信息,在对病变的良恶性鉴别诊断中起到了很大的作用。     

多平面经食管旋转扫描超声心动图像的三维重建

目的 进行经食管旋转扫描超声心动图像的三维重建算法的基础研究,并开发相应三维重建软件系统。方法 首先,使用食管导入旋转扫描超声成像技术获得一系列在空间按一定角度分布的动态超声心脏图像,并同步记录心电信号。然后,根据心电及角度信号提取正确原始切片图像,进行预处理,并利用三维直接匹配插值方法对旋转扫描超声心动图像进行插值,获得规则体数据。最后,采用直接体绘制方法对体数据进行重建。结果 实现了全部重建算法,并对一组旋转扫描超声心动图像进行了三维重建实验,获得了左心室的真实感三维重建图像。结论 由于经食管扫描超声心动图像原始质量较好,并且本研究中采用了针对超声图像自身特点的图像预处理和三维直接插值方法,使得我们可以获得高质量的超声心脏体数据,从而获得良好的重建结果。     

彩色多普勒超声立体血流成像结合心肌做功指数检测超体重孕妇胎儿心脏的临床价值

目的 探讨彩色多普勒超声立体血流成像结合心肌做功指数(myocardial performance index,MPI)对超体重孕妇胎儿心脏的临床价值。方法 选取我院120例超体重孕妇(25 kg/m²≤孕前BMI <35 kg/m²),随机分为立体血流成像技术组(60例)和二维斑点追踪成像(two dimensional speckle tracking imaging,2D-STI)组(60例)。立体血流成像技术组实施彩色多普勒血流成像(color Doppler flow imaging,CDFI)检查和MPI胎儿左心-心肌做功指数智能检测,2D-STI组实施2D-STI检查以获取胎儿心脏结构参数、心脏指标、心肌收缩功能和心肌做功指数,比较两种检查方法的诊断准确性和Kappa值一致性检验结果。结果 立体血流成像技术组和2D-STI组检测所得胎儿心脏结构参数中的右心房横径、左心室横径、右心室横径和全心球形指数比较,心脏指标中的二尖瓣环e/a和三尖瓣E/A比较,心肌收缩功能及应变指标中的左心室GLS、右心室GLS、和三尖瓣环e/a和三...     

心腔内超声评价心脏结构和左室收缩功能的实验研究

目的:研究心腔内超声探查心脏结构和评价左室收缩功能的方法。方法:AcuNav心腔内超声导管置于健康犬右房、右室,二维图像显示左右心腔、心瓣膜、肺静脉、冠状动脉、主动脉、肺动脉等结构,彩色及频谱多普勒记录血流状况。开胸制作犬急性心肌缺血再灌注模型,观察室壁运动和左室射血分数改变。结果:所有目标结构及血流均获得清晰显示,未发生导管相关的严重并发症。心腔内超声示心肌缺血再灌注过程中前壁厚度、增厚率、左室射血分数动态改变。结论:心腔内超声可安全、清晰地显示心脏结构和血流状态,并评价左室收缩功能。     

谐波成像技术临床应用

近年来，随着计算机技术的迅猛发展，超声检查技术也得到了明显改进，其图像质量有了很大的提高，其中最为重要的是在二维和彩色多普勒超声检查中应用谐波成像技术，极大地提高了信噪比，更清晰地显示被检脏器的图像及血流状态，为临床提供更为可靠的诊断信息。现简要介绍谐波成像技术的     

多普勒超声心动图评价左室舒张功能的临床应用进展

多普勒超声心动图评价左室舒张功能的检测途径主要包括频谱多普勒测定的二尖瓣口血流和肺静脉血流、组织多普勒成像测定的左室心肌长轴运动以及彩色M型多普勒测定的左室舒张早期血流传播速度，三种技术方法的综合分析能够对左室舒张功能作出比较准确的评价，并且为估测左室充盈压和估计预后提供重要的信息。     

乳腺癌的彩色多普勒及高频超声表现(附82例分析)

目的 探讨乳腺癌的高频超声图像特征及彩色多普勒血流表现。方法回顾性分析82例经手术、病理证实为乳腺癌的高频超声表现及彩色多普勒血流特征：结果乳腺癌的高频超声图像像，如肿块的形态、边界、内部回声、钙化、衰减及彩色多普勒血流，有一定的特征。结论高频超声与彩色多普勒技术联合应用诊断乳腺癌，其诊断符合率会有一定的提高。     

Differential flow imaging by NMR

A new method for spatially resolved NMR flow measurements, named differential flow imaging (DFI), is introduced and experimentally verified. The DFI technique is based on the fact that flow velocity in any direction may cause a pixel position shift in the phase-encoding direction of a 2DFT NMR image. In this method two flow-influenced magnitude images are obtained by properly encoding and/or compensating the flow velocity. A spatial map of the desired component of the flow velocity can consequently be calculated from these two images. Since the DFI technique uses only the magnitude information of the complex images, it is not sensitive to systematic phase errors in contrast to other methods which are based on the phase measurements. On the other hand, the DFI technique can be combined with the phase measurement methods to perform multidimensional flow measurements in a shorter data acquisition time when the phase errors are small or corrected.     

Color-Doppler instruments: their design principles and modes of use]

The use of color-Doppler US equipment allows the clinician to evaluate, at the same time and within the same image, both shape and structure of the examined organs and the flow patterns in the vessels within them. Such information as direction and velocity of blood flow are displayed with a variety of intravascular colors, according to a conventional code. Moreover, this diagnostic method can provide physiological and anatomical pieces of information in the same image and is therefore widely used in medical imaging. However, the images obtained by means of color-Doppler units are not always easy to understand and diagnostic misinterpretations may occur. In this paper we will summarize the physical and technological principles on which such units are based. In the first half of paper, the problems relative to acquisition and construction of the images are presented, together with the different technical approaches used to obtain flow velocity information. Moreover, the relationships between the "black-and-white" and the "color" parts of the images are described. The principles according to which color is assigned to vessels are reported, together with the patterns exhibited by a vessel according to the type of transducer used to examine it. The non-linear correlation between the color scale and flow velocities is also discussed. The second half of the paper deals with technical parameters of color-Doppler scanning, discussing the criteria of choice of transducers, the determination of Doppler angle, the setting of both wall filters and scanning depth. The problem of pulse repetition frequency (PRF) setting is also addressed; this parameter is especially critical in color-Doppler studies. The authors believe that careful setting of all examination parameters and the good knowledge of the physical and technological factors underlying color-Doppler images are the basis for a correct and useful approach to this fascinating technique.     

基于Amira软件的小腿外侧供区皮瓣三维可视化设计

目的 利用个人电脑(PC),结合图像处理软件Amira 4.1对小腿外侧皮瓣进行三维重建,建立皮瓣动脉的可视化数字模型.方法 明胶-氧化铅混悬液灌注的新鲜成人标本1具,行下肢多排螺旋CT扫描,观测腓动脉的分布及彼此间的吻合情况,将数据输入个人PC,利用Amira软件,经剪切、分割、表面重建及体绘制等步骤,根据解剖结构特点,对皮肤及其血管进行三维重建,获得立体形态的动脉皮瓣结构.结果 重建了皮瓣主要构成,重建的三维结构可以多彩色、透明或任意组合显示,经不同角度观察,整体显示清晰、实体感强,皮肤、动脉的相互关系一目了然.在三维表面重建的图像中可清楚地观察各解剖结构的形态,特别是皮瓣动脉的分支及其体表投影得到了很好的显示.结论 小腿外侧皮瓣三维重建对基础研究、临床试验及手术规划具有重要价值,应用Amira软件可为三维建模提供基础.     

Direct cardiac NMR imaging of heart wall and blood flow velocity

Nuclear magnetic resonance (NMR) imaging is used to produce in the same scan both anatomical and functional information of the heart and great vessels. A method is described to generate velocity images by the use of phase shifts for moving spins induced by imaging gradients under electrocardiogram (ECG) synchronized imaging conditions. The influence of the different gradients is discussed together with methods to obtain velocity information for each gradient direction separately. The results, obtained with a 0.14 T resistive NMR scanner and normal volunteers, show the spatial velocity distribution in the aorta and heart walls in color scale images. The feasibility of velocity calculations is demonstrated and some applications are given. The present results indicate the possibility of quantitative flow and motion analysis with ECG synchronized NMR imaging.     

多层螺旋CT颞骨三维成像与解剖学的对照研究

为了验证多层螺旋CT三难成像的测量数据的准确性，选取10％甲醛固定的成人头颅标本12具（24侧），进行颞骨部位的扫描，并应用表面遮盖显示，容积显示技术对颞骨的三维成像，对几处明显的结构进行测量，然后，再解剖测量，对比，结果显示，多层螺旋CT立体图像清晰，各种表面结构清楚，多层螺旋CT成像的测量数据与解剖测量的数据一致，无统计学的差异，研究表明，多层螺旋CT成像测量的数据，可以直接指导临床。     

Reconstruction of blood propagation in three-dimensional rotational X-ray angiography (3D-RA).

This paper presents a framework of non-interactive algorithms for the mapping of blood flow information to vessels in 3D-RA images. With the presented method, mapping of flow information to 3D-RA images is done automatically without user interaction. So far, radiologists had to perform this task by extensive image comparisons and did not obtain visualizations of the results. In our approach, flow information is reconstructed by forward projection of vessel pieces in a 3D-RA image to a two-dimensional projection series capturing the propagation of a short additional contrast agent bolus. For accurate 2D-3D image registration, an efficient patient motion compensation technique is introduced. As an exemplary flow-related quantity, bolus arrival times are reconstructed for the vessel pieces by matching of intensity-time curves. A plausibility check framework was developed which handles projection ambiguities and corrects for noisy flow reconstruction results. It is based on a linear programming approach to model the feeding structure of the vessel. The flow reconstruction method was applied to 12 cases of cerebral stenoses, AVMs and aneurysms, and it proved to be feasible in the clinical environment. The propagation of the injected contrast agent was reconstructed and visualized in three-dimensional images. The flow reconstruction method was able to visualize different types of useful information. In cases of stenosis of the middle cerebral artery (MCA), flow reconstruction can reveal impeded blood flow depending on the severeness of the stenosis. With cases of AVMs, flow reconstruction can clarify the feeding structure. The presented methods handle the problems imposed by clinical demands such as non-interactive algorithms, patient motion compensation, short reconstruction times, and technical requirements such as correction of noisy bolus arrival times and handling of overlapping vessel pieces. Problems occurred mainly in the reconstruction and segmentation of 3D-RA images in cases of complex AVMs. The concentration of injected contrast agent was often not sufficient to provide highly contrasted vessels in 3D-RA images. Another segmentation-related problem is known as 'kissing vessels' [19]. Kissing vessel artifacts introduce artificial vessel junctions and thereby distort the feeding structure of the vessel. This may finally cause implausible flow reconstruction results and inverse flow directions in vessel segments. We are currently planning to validate our reconstruction results using particle imaging velocimetry (PIV). PIV experiments with phantoms, for which the true flow parameters are known, will allow for the assessment of the accuracy of our contrast agent based method. In the context of computational fluid dynamics techniques, the potential of the presented flow reconstruction method is high. Flow reconstruction results based on the presented method could be used both as boundary conditions for simulations and as a reference for the validation of simulation results. Computational fluid dynamics provide useful information such as arterial wall shear stress and complex flow patterns in aneurysms.     

Medical image diagnostics based on computer-aided flow analysis using magnetic resonance images

Most of the cardiac abnormalities have an implication on hemodynamics and affect cardiovascular health. Diagnostic imaging modalities such as computed tomography and magnetic resonance imaging provide excellent anatomical information on myocardial structures, but fail to show the cardiac flow and detect heart defects in vivo condition. The computerized technique for fluid motion estimation by pixel intensity tracking based on magnetic resonance signals represents a promising technique for functional assessment of cardiovascular disease, as it can provide functional information of the heart in addition to analysis of its anatomy. Cardiovascular flow characteristics can be measured in both normal controls and patients with cardiac abnormalities such as atrial septal defect, thus, enabling identification of the underlying causes of these flow phenomena. This review paper focuses on an overview of a flow analysis scheme based on computer-aided evaluation of magnetic resonance intensity images, in comparison with other commonly used medical imaging modalities. Details of the proposed technique are provided with validations being conducted at selected abnormal cardiovascular patients. It is expected that this new technique can potentially extend applications for characterizing cardiovascular defects and their hemodynamic behavior.     

Quantitation in positron emission tomography: 8. Effects of nonlinear parameter estimation on functional images

Functional images used in positron emission tomography (PET) have the advantage of presenting simultaneously the anatomical and functional information in cross-sectional body slices. However, the nonlinearity in parameter estimation, when combined with the finite image resolution, can cause systematic errors or biases in the estimated functional parameters. The effect of this error on blood flow images, which are commonly used in PET, is investigated in this study. Computer-simulated brain and heart phantoms of realistic configurations are used to examine the effect of various factors, such as imaging resolution, estimation nonlinearity, and structure configuration. The nonlinearity characteristics of six commonly used blood flow estimation techniques are simulated. Results show that structure boundaries on parametric images between tissues of different blood flows do not usually coincide with the true anatomical boundaries and would thus cause an apparent change in the cross-sectional size of the structures. The regional blood flow values as obtained from the blood flow images are usually lower than the true values. The severity of these effects is dependent on the characteristics of the flow estimation technique, the image resolution, and the size and shape of the structure. Although image resolution is a major factor in causing errors in the parametric images, its improvement, within the range examined in the present study [from 1.5 to 0.5 cm full width at half maximum (FWHM)], is not found to reduce drastically the underestimation of blood flow in brain phantom. The effect on boundary shift, however, is found to be in proportion to the FWHM of image resolution. Implications of these effects on generation, interpretation, and comparison of parametric/functional images are discussed.     

彩色三维超声在肝脏实性占位性病变中的诊断价值

目的 运用彩色三维多普勒超声对肝脏实质性占位病变进行三维重建,观察病变的形态、大小及内部血供情况,探讨彩色三维超声的诊断价值。方法 二维超声显示肝脏实性占位病变患者28例,使用德国TomTec公司腹部彩色三维超声成像仪,采用自由臂方式对肝脏病变处及其周围进行扫查取像,取样结束后在三维超声仪上进行脱机后处理,计算程序可自动算出球体的体积、其内部的血流容积及两者的比例。结果 肿瘤体积最大者117．0ml,最小仅为2．0ml。三维超声可显示肿瘤供给血管走行及其分支情况,并可透视肿瘤血管分布情况。部分病灶在二维图像上呈现“晕环”、“绕行”的肿瘤周边血管在三维重建后显示出“抱球征”,展现血管全貌,进入肿瘤内部后呈现出“提篮征”,发出多支小血管,显示了恶性的血供特征。结论 彩色三维超声可对肝脏实性占位性病变的形态、体积及其周边及内部血供情况进行综合评价,丰富了超声诊断依据,并可为超声介入治疗提供精确的定位信息。     

正常人膝关节软骨MR成像和软骨重建

目的　研究正常人膝关节软骨的MR成像和软骨三维重建方法 ,为临床诊治关节软骨病变提供科学依据。材料与方法　使用Philips 1.0T磁共振成像仪对 2 0例志愿者行软骨序列扫描 ,然后进行三维软骨重建。 结果　软骨序列及软骨重建技术可以清晰显示软骨的结构 ,关节软骨在SE序列上显示为 3层结构 ,在SPIR/ 3D/FFE/T1WI上最多显示为 4层结构 ,重建后的软骨像具有立体直观的效果 ,并具有良好的空间分辨率。结论　软骨MR成像和软骨重建能清晰显示膝关节的软骨结构 ,可为临床对骨关节病变的诊断和治疗提供帮助。