Coupling formalized knowledge bases with object-based image analysis

Object-based image analysis (OBIA) is a widely used method for knowledge-based interpretation of very high resolution imagery. It relies on expert knowledge to classify the desired classes from the imagery at hand. The definition of classes is subjective, usually project-specific and not shared with the community. Ontologies as a form of knowledge representation technique are acknowledged as solution to establish and document class definitions independently of an OBIA framework. However, ontologies have not yet been strongly integrated in this image analysis framework. This paper presents a method to automatically integrate ontologies in OBIA. The method has been implemented as a tool to be used with the eCognition® software (Trimble, Sunnyvale, CA, USA). A case study was conducted for classifying the land cover classes defined by the Environment Agency of Austria in the Land Information System Austria (LISA) project using WorldView-2 image. The strength of this approach is the direct integration of ontologies into the OBIA process, which reduces the effort necessary to define the classes for image analysis and simultaneously reduces its subjectivity.     

The effect of input data transformations on object-based image analysis

The effect of using spectral transform images as input data on segmentation quality and its potential effect on products generated by object-based image analysis are explored in the context of land cover classification in Accra, Ghana. Five image data transformations are compared to untransformed spectral bands in terms of their effect on segmentation quality and final product accuracy. The relationship between segmentation quality and product accuracy is also briefly explored. Results suggest that input data transformations can aid in the delineation of landscape objects by image segmentation, but the effect is idiosyncratic to the transformation and object of interest.     

Assessment of patient pain in the postoperative context

Because of its subjective nature, the assessment of pain requires the use of comprehensive practices that accurately reflect a patient's experiences of pain. The purpose of this study was to determine how nurses make decisions in their assessment of patients' pain in the postoperative clinical setting. An observational design was chosen as the means of examining pain activities in two surgical units of a metropolitan teaching hospital in Melbourne, Australia. Six fixed observation times were selected. Each 2-hour observation period was examined 12 times thus resulting in 74 observations. In total, 316 pain activities were determined. Five themes relating to assessment were identified from the data analysis: simple questioning, use of a pain scale, complex assessment, the lack of pain assessment, and physical examination for pain. The study identified how nurses' prioritization of work demands created barriers in conducting timely and comprehensive pain assessment decisions.     

A comparison of three different filters for speckle reduction of Doppler spectra

This paper is concerned with speckle suppression in Discrete Fourier Transform based Doppler signals by means of digital image processing. The Doppler spectrum is treated as a greyscale image, and three different noise smoothing algorithms are applied to it. These are the Double Window Modified Trimmed Mean filter, which is nonlinear, and Lee's and the directional filter, which are adaptive in the sense that the smoothing performed by them at each point of the image is controlled by a local image measure. In order to evaluate the performance of the filters, they were applied to a variety of regular waveforms obtained from a physiological flow phantom. Ensemble averaging of a large number of unfiltered spectra was used as the "gold standard" in the evaluation, i.e., as the output of an ideal filter which reveals the exact nature of the underlying Doppler spectrum after speckle has been eliminated. Comparison of the "gold standard" with the ensemble averaged filtered data allowed the noise reduction, bias and distortion of the maximum frequency envelope introduced by filtering to be examined. Overall, the best performance was offered by the directional filter whose action was controlled by the combination of the local edge content and the slope of the least-squares-fit line passing through the data points along each particular direction.     

Development of a multi-scale object-based shadow detection method for high spatial resolution image

Effective treatment of shadows generated by the obstruction of trees and buildings is an inevitable task for extracting detailed spectral and spatial information from urban high-resolution images. Object-based shadow detection methods can take full advantages of spatial features in the urban very high resolution (VHR) images. However, the effect of different segmentation parameters for detecting shadows has not been well studied. In this study, we proposed an object-based method for shadow detection on urban high-resolution image and addressed quantitative assessment of segmentation. In proposed object-based method, a multi-scale segmentation method, known as fractal net evolution approach (FNEA), was employed to generate primitive objects; then, three spectral properties of shadows were fused based on Dempster–Shafer (D–S) evidence theory to identify shadows. In quantitative assessment, a method for ordering significance of parameters and deriving optimal parameters based on orthogonal experimental design was proposed to evaluate the impact of different segmentation variables on the accuracy of shadow detection. Experimental results indicate that the best overall accuracy (OA) for shadow detection of our method was 89.60% after segmentation parameters’ optimization and scale is the most influential parameter of FNEA segmentation parameters in determining the performance of shadow detection.     

Assessment of left ventricular torsion using speckle tracking echocardiography

Left ventricular (LV) torsion/twist, wringing motion of the heart showing clockwise rotation at the base and counter-clockwise rotation at the apex during systole and its rapid reversal at early diastole, is an important contribution to both LV systolic and diastolic function. Recent development of two-dimensional (2D) speckle tracking echocardiography allows the noninvasive measurement of LV twist in various cardiovascular pathologies, which may provide new understanding of LV mechanics. We review the clinical utility of measuring LV twist indices assessed by 2D speckle tracking echocardiography.     

Towards pointwise motion tracking in echocardiographic image sequences--comparing the reliability of different features for speckle tracking

In this paper, we studied the problem of feature-based motion tracking in echocardiographic image sequences. We described the relation between possible feature variations and different kinds of tissue motion using a linear convolution model. We also showed that motion-feature decorrelation (which means that the motion parameters estimated using feature tracking fail to represent the underlying tissue motion) compensation is an ill-posed inverse problem. Instead of finding a method that may provide better compensation results than previous approaches, we used an quantitative measure to compare the reliability of tracking features. Experiment results showed that the use of the reliability measure improved the robustness of displacement estimation. With the help of the reliability measure, we compared the performance of different features using simulations and phantom examples. While we noticed that the radio frequency (RF) signal outperforms the B-mode (BM) signal in the analysis of small deformation (e.g., less than 0.1% compression), we also found out that the BM signal works better than the RF signal in the analysis of large deformation (e.g., larger than 2% compression). The use of a band-passed filtered feature does not result in significant improvement in tracking.     

骨质疏松HR MRI图像处理及其价值探讨

目的评价骨质疏松高分辨MR图像处理及其应用价值。方法本组12例,其中女7例,男5例,年龄25-80岁,平均54.8岁。经双能X线骨密度仪测量(dual-energyX-rayabsorptiometry,DXA),分为骨松组和对照组(骨密度正常),每组6例。所有病例均行高分辨MR扫描。SIEMENS1.5T超导MR,3D-DESS序列,层厚0.73mm,像素大小312×312×730μm。扫描部位左跟骨,矢状面,扫描时间为11min。数据用共生矩阵(co-occurrenceMatrix)和局部灰度差分矩阵(neighborhoodgray-tonedifferencematrix,NGTDM)对MR图像进行了纹理分析,提取了熵、粗糙度等纹理特征,并对MR图像进行二值化,分离了骨小梁和骨髓。在此基础上对骨小梁的形态和网络结构进行分析,提取面积、骨架长度,欧拉数等数据,对骨松组和对照组进行统计学处理。结果两组数据在15个结构参数中,有11个参数有显著性差异,占73%。结论HR-MR二值化图像技术能区分骨松组和正常对照组。为HR-MR研究骨质疏松小梁微结构起到积极作用。部分参数的意义还有待进一步研究。     

斑点追踪显像技术评价急性心肌梗死患者左房功能的临床价值

目的 探讨斑点追踪显像（STI）技术评价急性心肌梗死（AMI）患者左房功能的临床价值。方法 选取我院29例急性心肌梗死患者（AMI组）及20例经体检、实验室检查和常规超声心动图检查无异常的高血压病患者（对照组）的心尖二腔和四腔观图像,应用STI技术获取左房前壁、下壁、侧壁、房间隔的应变率曲线。测定各房壁于左室收缩期、舒张早期、舒张晚期的峰值应变率（SRs、SRe、SRa）,计算平均峰值应变率（mSRs、mSRe、mSRa）。结果 与对照组比较,AMI组mSRs及mSRe显著降低,mSRa显著升高（P〈0．01）;AMI组mSRe和mSRa呈显著负相关（r=-0．72,P〈0．01）。结论 AMI患者左房储蓄功能和管道功能减低,辅泵功能增加;AMI患者左房管道功能与辅泵功能呈显著负相关。     

三维斑点追踪技术评价正常人左房心肌应变的初步研究

目的 探讨三维斑点追踪显像(3D-STI)技术评价正常成年人左房心肌应变的临床价值.方法 对健康成年志愿者60例采集全容积左室心尖四腔和两腔观图像并存储,运用3D-STI分析软件进行脱机分析,软件自动将左房心肌分为16节段,分别为前壁、前间隔、后间隔、下壁、后侧壁、前侧壁的基底段及中间段,以及前壁、间隔、侧壁、下壁的房顶段.比较左心房16个心肌节段之间纵向峰值应变(PALS)、纵向应变达峰时间(TPLS)、圆周峰值应变(PACS)、圆周应变达峰时间(TPCS)、面积峰值应变(PAAS)、面积应变达峰时间(TPAS)的差异.结果 ①基底段各壁PALS较房顶段各壁高,基底段前侧壁及后侧壁PALS较中间段高,中间段后间隔、下壁及后侧壁PALS高于房顶段间隔、下壁及侧壁;房顶段各壁的PACS及PAAS高于中间段及基底段各壁,后间隔基底段PACS低于中间段,以上差异均有统计学意义(P ＜0.05).②同一水平的各房壁间PALS、PACS、PAAS差异无统计学意义.③间隔TPLS、TPCS、TPAS小于侧壁,前壁TPLS、下壁TPCS及TPAS小于侧壁,差异均有统计学意义(P＜0.05).结论 3D-STI可反映正常人左房心肌应变规律,为评估不同病理状态下左房功能改变的位置和程度提供重要参考.     

应用超声二维斑点追踪成像技术评价扩张型心肌病患者左室扭转的初步研究

目的应用超声二维斑点追踪显像技术(STI)探讨扩张型心肌病患者(DCM)左室扭转(LVtw)运动特征。方法DCM患者33例,年龄匹配的健康志愿者30例。经胸采集3个心动周期标准左室基底部及心尖部短轴二维图像并存贮,运用Echo PAC超声工作站进行脱机分析,获取每个切面的旋转值。左室扭转值定义为左室心尖部旋转值与心底部旋转值的差值。对不同研究对象间心率差异进行时间校标。结果从左室心尖来看,正常人LVtw运动主要表现为心底部顺时针旋转和心尖部逆时针旋转,心脏整体表现为心动周期内逆时针方向为主的扭转运动。DCM患者LVtw运动于收缩期仍维持心底部顺时针旋转、心尖部逆时针旋转及心脏整体收缩期逆时针方向的扭转运动,但其左室扭转峰值[(6.56±2.19)°/(14.44±1.55)°,P<0.001]显著减低。左室峰值扭转与左心功能显著正相关,相关关系密切(Spearman相关系数r=0.762,P=0.00)。结论DCM患者组收缩期左室扭转值减低对于左室收缩功能有很大影响。STI技术为准确地评估左心室扭转运动特征提供了全新的定量工具,具有广阔的临床应用前景。     

三维斑点追踪技术评价正常成人左房功能的初步研究

目的：探讨三维斑点追踪技术(Three-dimensional speckle tracking imaging, 3D-STI)评价正常成人左房功能的应用价值。方法：选取健康志愿者共104例,按年龄分为青年组(年龄18~44岁)、中年组(年龄45~59岁)和老年组(年龄≥60岁)。采集心脏全容积图像并应用3D-STI软件脱机分析,获取左房容积曲线,得到左房最大容积(LAVmax)、最小容积(LAVmin)及收缩前容积(LAVpre)。计算出左房总排空容积LAVt、总排空分数LATEF、扩张指数EI、被动排空容积LAVp、被动排空分数LAPEF、主动排空容积LAVa、主动排空分数LAAEF、被动排空容积占总排空容积比率PE、主动排空容积占总排空容积比率,以上数据均用体表面积(BSA)标化。以上指标分别反映：(1)存储器功能： LAVmaxi、LAVmini、LAVprei 、LAVti、LATEF、EI;(2)管道功能：LAVpi、LAPEF 、PE(3)助力泵功能：LAVai、LAAEF 、AE。结果： 1、存储器功能指标：LAVmaxi、LAVprei、LAVmini、LAVti随年龄逐渐增大,三组间比较均有统计学意义(P＜0.05);LATEF、EI三组间无显著差异(P＞0.05);2、管道功能指标：与青、中年组相比,老年组LAVpi增大(P＜0.05);中、老年组均较青年组LAPEF 、PE减低(P＜0.05);4、助力泵功能指标：LAVai 、LAAEF随年龄增加而增大(P＜0.05);中、老年组均较青年组AE增大(P＜0.05)。结论：三维斑点追踪技术可用于检测不同年龄段正常成人的左房容积及功能的变化规律,可能为临床监测左房功能改变和发现亚临床心血管疾病提供一种可靠的辅助手段。     

正常人左室收缩功能的超声三维斑点追踪研究

目的运用三维斑点追踪成像技术(3D-STI)评价正常人左室短轴及长轴心肌应变特征,探讨其对正常人左室收缩功能的评判价值。方法健康志愿者45名,采集标准左室长轴心尖四腔、三腔切面左室全容积图像进行在线分析,自动计算左室舒张末期容积(LVEDV)、左室收缩末期容积(LVESV)、左室射血分数(LVEF)、左室短轴径向各水平收缩期峰值及平均应变、左室短轴环向各水平收缩期峰值及平均应变、左室长轴纵向各水平收缩期峰值及平均应变,分析各应变指标变化情况。结果正常人左室短轴径向各节段收缩期峰值及平均应变,基底水平较中间段水平增大(P<0.05),中间段水平较心尖水平增大(P<0.05),基底水平较心尖水平增大(P<0.01)。正常人左室短轴环向各节段收缩期峰值及平均应变,心尖水平较中间段水平增大(P<0.05),中间段水平较基底水平增大(P<0.05),心尖水平较基底水平增大(P<0.01)。正常人左室长轴纵向收缩期峰值及平均应变,心尖水平较中间段水平增大(P<0.05),中间段水平较基底水平增大(P<0.05),心尖水平较基底水平增大(P<0.01)。结论 3D-STI可无创、客观评价正常人在不同水平和不同节段径向、环向、纵向心肌应变,为定量评价正常人左室收缩功能提供了一种新的思路。     

超声二维应变成像技术评价陈旧心肌梗死患者心肌存活的可行性

目的:探讨超声二维应变成像技术评价陈旧心肌梗死患者心肌存活的可行性。方法:72例准备接受血运重建术的陈旧心肌梗死患者,于术前1周行双核素心肌灌注与代谢扫描,以F-FDG代谢显像在18灌注减低节段内出现≥1分的改善视为存活心肌。同期应用二维应变成像技术检测左室短轴基底、中间及心尖各节段径向峰值应变(PRS)、圆周方向峰值应变(PCS),比较存活心肌组与非存活心肌组应变参数。结果:常规超声共检出运动异常节段258个,经同位素心肌灌注-代谢扫描诊断存活心肌节段数133个,坏死心肌节段数125个。对照组、存活心肌组的PRS和PCS均明显高于坏死心肌组(P<0.01);对照组与存活心肌组PCS无明显差异(P﹥0.05),对照组PRS明显高于显存活心肌组(P<0.01)。以峰值RS≥18.32%、峰值CS≤-10.54%为截断值,预测存活心肌敏感性分别为73.8%、75.6%,特异性分别为89.3%、85.6%,ROC曲线下面积分别为0.84和0.79。结论:超声二维应变成像技术预测存活心肌是可行的,为定量评估心肌梗死后存活心肌性提供了一种新的方法。     

应用三维斑点追踪成像技术评价心脏再同步化治疗的短期疗效

目的：探讨三维斑点追踪成像（Three-dimensional speckle tracking imaging,3D-STI）技术评价心脏再同步化治疗（Cardiac resynchronization therapy,CRT）短期疗效的临床价值。方法：充血性心力衰竭患者15例（心衰组）和正常志愿者20例（对照组）,其中心衰组分别于CRT术前、术后1周、术后1月和术后3月,应用3D-STI测量左心室舒张末期容积（LVEDV）、左心室收缩末期容积（LVESV）、左心室射血分数（LVEF）和左心室不同步性参数,即左心室16个节段的面积追踪达峰时间标准差（AT-SD）和达峰时间最大差值（AT-Dif）。统计学方法采用两独立样本的t检验和单组重复测量资料的方差分析。结果：心衰患者CRT术前LVEDV、LVESV、AT-SD、AT-Dif大于对照组,心衰患者CRT术前LVEF低于对照组,差异均有统计学意义（P<0.05）。心衰患者术后1周时左心室的AT-SD、AT-Dif均较术前明显减小（P<0.0083）,术后1周以后左心室不同步性无进一步改善（P>0.0083）。LVEDV、LVESV随时间延长逐渐下降（P<0.0083）,LVEF随时间延长逐渐增加（P<0.0083）。结论：3D-STI为评价CRT的短期疗效提供了有价值的信息。     

Correction for spatial averaging in laser speckle contrast analysis

Practical laser speckle contrast analysis systems face a problem of spatial averaging of speckles, due to the pixel size in the cameras used. Existing practice is to use a system factor in speckle contrast analysis to account for spatial averaging. The linearity of the system factor correction has not previously been confirmed. The problem of spatial averaging is illustrated using computer simulation of time-integrated dynamic speckle, and the linearity of the correction confirmed using both computer simulation and experimental results. The valid linear correction allows various useful compromises in the system design.     

Assessment of the geolocation accuracy of YG-13A high-resolution SAR data

The YG-13A mission, launched in late 2015, is the first Chinese synthetic aperture radar (SAR) satellite to achieve sub-meter resolution. In this paper, we briefly introduce this milestone satellite and describe a method for improving YG-13A’s absolute positioning accuracy. We evaluated the plane and three-dimensional absolute positioning accuracy over five test sites. The results indicate that high-accuracy absolute positioning can now be achieved with a horizontal accuracy of 3 m or better for strip-map data and 2 m or better for sliding spot data, without regard to the elevation error. In addition, the three-dimensional absolute positioning accuracy in plane and elevation is within 3 m and 2 m, respectively, which satisfies the requirements for high-precision three-dimensional control points.     

三维斑点追踪技术评价肥厚型心肌病患者左心室收缩不同步性

目的 应用三维斑点追踪显像(3D-STI)技术评价肥厚型心肌病(HCM)患者左室收缩不同步性.方法 连续纳入HCM患者93例,其中非梗阻性HCM(HNCM)患者63例,梗阻性HCM(HOCM)患者30例,选取健康对照组72例.应用超声诊断仪(iE33)获得和分析二维图像,利用X5-1矩阵探头获取左室三维全容积动态图像,运用TomTec脱机软件进行分析,获取左室16节段面积、环形、纵向、径向应变达峰时间并计算各节段各方向的标准差(TAS-SD、TCS-SD、TLS-SD、TRS-SD)以及任意两节段面积、环形、纵向、径向应变达峰时间最大差值(TAS-diff、TCS-diff、TLS-diff、TRS-diff),同时计算其标准化后的值(TAS-SD％、TCS-SD％、TLS-SD％、TRS-SD％、TAS-diff％、TCS-diff％、TLS-diff％、TRS-diff％)等不同步参数.比较三组间上述参数之间的差异.结果 与对照组比较,HCM组左室收缩及舒张末期容积显著减小,每搏量显著减少,左室质量显著增加,左室舒张末期室间隔厚度显著增加,左室舒张末期后壁厚度增加(均P＜0.05),左室射血分数差异无统计学意义(P＞0.05).HCM组TAS-SD％、TLS-SD％、TRS-SD％、TAS-diff％、TLS-diff％、TRS-diff％均较对照组延长,差异有统计学意义(P＜0.05),而TCS-SD％、TCS-diff％差异无统计学意义(P＞0.05).与HNCM组比较,HOCM组TAS-SD％、TRS-SD％、TCS-SD％、TAS-diff％、TCS-diff％、TRS-diff％显著延长(P＜0.05),而TLS-SD％、TLS-diff％差异无统计学意义(P＞0.05).不同步参数与左室流出道压差存在线性正向相关性.结论 HCM患者左室心肌收缩存在明显不同步,表明HCM患者早期存在收缩功能的异常,3D-STI为评价HCM患者早期左室收缩功能的异常提供了新的方法.