Three-dimensional speckle tracking

Two-dimensional speckle tracking is a useful technology. Nevertheless, it has some limitations because the heart has three dimensions. The recent development of three-dimensional speckle tracking technology provides a new diagnostic tool. By using this new method, a more complete and probably accurate evaluation of global and segmental left ventricular function may be performed. Three-dimensional speckle tracking is a promising tool to provide new insights into left ventricular function.     

3-D correlation-based speckle tracking

Widely-used 1-D/2-D speckle tracking techniques in elasticity imaging often experience significant speckle decorrelation in applications involving large elevational motion (i.e., out of plane motion). The problem is more pronounced for cardiac strain rate imaging (SRI) since it is very difficult to confine cardiac motion to a single image plane. Here, we present a 3-D correlation-based speckle tracking algorithm. Conceptually, 3-D speckle tracking is just an extension of 2-D phase-sensitive correlation-based speckle tracking. However, due to its high computational cost, optimization schemes, such as dynamic programming, decimation and two-path processing, are introduced to reduce the computational burden. To evaluate the proposed approach, a 3-D bar phantom under uniaxial compression was simulated for benchmark tests. A more sophisticated 3-D simulation of the left ventricle of the heart was also made to test the applicability of 3-D speckle tracking in cardiac SRI. Results from both simulations clearly demonstrated the feasibility of 3-D correlation-based speckle tracking. With the ability to follow 3-D speckle in 3-D space, 3-D speckle tracking outperforms lower-dimensional speckle tracking by minimizing decorrelation caused by pure elevational translation. In other words, 3-D tracking can push toward solely deformation-limited, decorrelation-optimized speckle tracking. Hardware implementation of the proposed 3-D speckle tracking algorithm using field programmable gate arrays (FPGA) is also discussed.     

Impact of acute normobaric hypoxia on regional and global myocardial function: a speckle tracking echocardiography study

Aim of this study was to evaluate the influence of normobaric hypoxia on myocardial function in healthy humans. Fourteen subjects underwent two-dimensional speckle tracking echocardiography (2D-STE) examination during normoxia and in a normobaric hypoxia chamber. Examinations were performed at rest and during bicycle exercise test. The following parameters were quantified in both atria and ventricles by 2D-STE: Global Strain (S), systolic strain rate (SR_S), early (SR_E) and late (SR_A) diastolic strain rate. During hypoxia SR_S and SR_E increased significantly in both ventricles compared to baseline. The increase of LV SR_S and SR_E during normoxic exercise was significantly higher when compared with exercise under hypoxia (for SR_S ?0.55 ± 0.22 vs. ?0.34 ± 0.24 1/s, p = 0.024; for SR_E 0.56 ± 0.29 vs. 0.23 ± 0.29 1/s, p = 0.005). For the right ventricle (RV) no significant difference of exercise induced increase of systolic contractility was found (SR_S ?1.07 ± 0.53 under normoxia vs. ?1.28 ± 0.24 1/s under hypoxic conditions, p = 0.47). A shift from passive conduit (SR_E) to active contraction (SR_A) phase during hypoxia was noted for the right atrium (RA) (SR_E/SR_A 0.72 ± 0.13 under hypoxia vs. 1.17 ± 0.17 under normoxia). The ratio SR_E/SR_A of RA was closely related to pulmonary systolic pressure (r = ?0.78, p < 0.001). Exposure to normobaric hypoxia leads to an increase of regional myocardial deformation in both ventricles. The contractile reserve during hypoxic exercise is reduced in LV, whereas RV systolic deformation rate is maintained. In addition, hypoxia had an impact on the ratio of passive conduit to active contraction phase in right atrium.     

三维及二维斑点追踪技术检测冠状动脉狭窄临床价值的对比研究

目的 应用三维斑点追踪技术(3D-STI)和二维斑点追踪技术(2D-STI)分析冠状动脉狭窄患者左心室局部和整体应变值,评价左心室收缩功能,比较两种技术检测冠状动脉狭窄的临床应用价值.方法 对照组32例,冠状动脉狭窄组39例(均经冠状动脉造影确诊),冠状动脉狭窄组心肌节段分为缺血节段和非缺血节段,经胸采集左室二维及全容积三维动态图像,进行脱机分析,3D-STI指标包括:三维长轴应变(3D-LS)、三维圆周应变(3D-CS)、三维径向应变(3D-RS)、三维面积应变(3D-AS)、三维整体长轴应变(3D-GLS)、三维整体圆周应变(3D-GCS)、三维整体径向应变(3D-GRS)、三维整体面积应变(3D-GAS);2D-STI指标包括:二维长轴应变(2D-LS)、二维圆周应变(2D-CS)、二维径向应变(2D-RS)、二维整体长轴应变(2D-GLS)、二维整体圆周应变(2D-GCS)、二维整体径向应变(2D-GRS).比较二维和三维在冠状动脉狭窄组缺血节段和非缺血节段中的节段性应变均值及在对照组和冠状动脉狭窄组中的整体应变均值.并对2DSTI和3D-STI的整体应变值和左室射血分数(LVEF)进行相关性分析.结果 冠状动脉狭窄组缺血节段和非缺血节段的2D-LS、2D-CS、3D-LS、3D-CS、3D-AS差异有统计学意义(P＜0.05).其中缺血节段的2D-LS、3D-LS、3D-AS较非缺血节段明显减低(P＜0.001),ROC曲线表明2D-LS、3D-LS、3D-AS诊断冠状动脉狭窄患者心肌缺血的灵敏度分别为60.1％、64.2％、74.0％,特异度分别为60.0％、61.0％、63.1％.对照组和冠状动脉狭窄组的2D-GCS、2D-GRS差异无统计学意义(P＞0.05),而冠状动脉狭窄组的2D-GLS、3D-GLS、3D-GCS、3D-GRS、3D-GAS较对照组明显减低,差异有统计学意义(P＜0.05).ROC曲线表明2D-GLS、3D-GLS、3DGAS诊断冠状动脉狭窄的灵敏度分别为61.3％、73.3％、79.3％,特异度分别为65.4％、66.0％、70.8％.3D-GAS诊断冠状动脉狭窄的灵敏度和特异度最高.相关性分析显示2D-GLS、2D-GCS、2D-GRS与LVEF相关(r1=-0.668,P＜0.001;r2--0.551,P＜0.001;r3-0.310,P＜0.05),而3D-GLS、3D-GCS、3D-GRS、3D-GAS与LVEF亦相关(r1=-0.634,P1＜0.001;r2=-0.672,P2 ＜0.001;r3=0.698,P3 ＜0.001;r4=-0.707,P4 ＜0.001),其中3D-GAS与LVEF的相关性相对较高.结论 3D-STI较2D-STI能更准确评价冠状动脉狭窄患者早期左室局部及整体收缩功能的变化,而来源于3D-STI的面积应变检测冠状动脉狭窄的灵敏度和特异度更高些.     

对比三维斑点追踪技术和二维斑点追踪技术评价正常人左心室心肌应变

目的 应用二维斑点追踪成像（2D-STE）与三维斑点追踪成像（3D-STE）技术评估正常人左心室心肌应变。方法 对34名正常人进行左心室心肌二维、三维图像采集,通过二维图像获取左心室心肌收缩末期17节段纵向应变（LS）、18节段环向应变（CS）及径向应变均（RS）,通过三维图像获得面积应变（AS）、LS、RS及CS。结果 3D-STE与2D-STE的LS和CS均自基底段至心尖段逐渐增大,RS均逐渐减。与2D-STE相比,3D-STE测得的LS较小,CS较大（P均<0.05）。3D-STE所测的AS与LVEF相关性最强（r=-0.720,P<0.05）。3D-STE获取图像及脱机分析时间明显少于2D-STE（P均<0.05）。结论 3D-STE是更全面、省时、高效的应变测量方法。作为3D-STE的新型应变参数,AS能更全面地反映左心室收缩功能。     

超声斑点追踪显像的临床应用进展

超声斑点追踪显像(speckle tracking strain imaging,STI)是一种新的超声心动图功能成像技术。本文对其主要临床应用现状进行综述,重点阐明该技术在冠心病、心肌病、瓣膜病等疾病诊断和治疗中的临床应用价值和局限性。     

斑点追踪技术对研究心肌再灌注损伤的应用价值

目的：应用斑点追踪技术研究再灌注损伤对心肌收缩功能的影响。方法：将20只健康成年杂种犬左冠状动脉第一对角支下方结扎180 min并再灌注120 min，分别对结扎前、结扎即刻、结扎180 min及再灌注即刻、60 min和120 min基底水平、乳头肌水平和心尖水平心肌的圆周应变进行比较。结果：基底水平心肌再灌注即刻圆周应变下降，再灌注后上升，高于基础状态。乳头肌水平心肌再灌注后圆周应变上升，仍低于基础状态，没有显著性差异。心尖水平心肌再灌注后上升，低于基础状态且有显著性差异。结论：斑点追踪技术能够客观准确的评价再灌注损伤对心肌收缩功能的影响，为尽早解除冠脉梗阻状态及治疗方案的选择提供有效的参考指标。     

An efficient speckle tracking algorithm for ultrasonic imaging

An efficient speckle tracking algorithm is proposed for motion estimation in ultrasonic imaging. Speckle tracking involves a matching process and a searching process. The matching process of the proposed algorithm is based on a Block Sum Pyramid algorithm that significantly reduces the computational complexity while maintaining the same accuracy as the conventional sum of absolute difference approach. The searching process, on the other hand, is based on a multilevel search strategy rather than the full-search strategy used by most conventional tracking methods. Both simulated speckle images and clinical breast images were used to test the performance of the proposed algorithm. The results show that the computation efficiency is improved by up to a factor of five over the conventional approach. The improved efficiency enables real-time or near-real-time implementation of motion estimation in ultrasonic imaging, which is particularly beneficial in areas such as blood flow estimation, elasticity imaging, speckle image registration, and strain compounding.     

Left atrial strain by three-dimensional speckle tracking echocardiography

The International Journal of Cardiovascular Imaging -     

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.     

斑点追踪成像技术在心肌病中的应用进展

心肌病是一组由各种病因引起的心室结构改变和心肌室壁功能受损而导致的心脏功能进行性障碍,临床常并发心律失常、栓塞、心力衰竭、猝死等。目前,心肌病及其所致的收缩性和舒张性心力衰竭仍为危害公众健康、特别是成年人健康的严重问题[1]。超声心动图作为一种心脏常规检查的手段,可评价心脏收缩和舒张功能,并可测定左心室或右室心充盈压,从而获得相应的血流动力学指标。但多项研究证实,新兴的斑点追踪成像技术（speckle tracking imaging,STI）在评价心肌运动功能方面价值更高[2]。因此,本文将对STI在心肌病中的临床应用及进展做一综述。     

Findings on 3D speckle tracking echocardiography in asymptomatic methamphetamine abusers

To detect potential cardiac abnormalities in asymptomatic methamphetamine abusers using three-dimensional speckle tracking echocardiography (3D STE). Fifty-three male methamphetamine abusers, free of cardiac symptoms/signs, were enrolled in this study. A control group of 53 age-matched male normal subjects was studied for comparison. Standard 3D, flow and tissue Doppler echo with measurements of left ventricular end-diastolic volume (LVEDV), end-systolic volume (LVESV), ejection fraction (LVEF), the ratio of the early to late diastolic transmitral filling velocity (E/A), the ratio of the early diastolic transmitral filling velocity to the early diastolic septal tissue velocity (E/E′) and 3D STE with measurements of global area strain (GAS), global longitudinal strain (GLS), global circumferential strain (GCS) and global radial strain (GRS) were performed, respectively. These echocardiographic parameters were compared between methamphetamine abusers and normal subjects, and receiver operating characteristic curve (ROC) analysis was done to differentiating methamphetamine abusers from normal subjects. LVESV, LVEDV, LVEF, E/A, E/E′ ratios and GRS were not significantly different between methamphetamine abusers and normal subjects (p?>?0.05). However, GAS, GLS and GCS were significantly less in methamphetamine abusers than in normal subjects (p?<?0.05). The areas under ROC (AUC) for GAS were greatest among all the 3D STE derived LV global strains (GAS vs. GLS, GCS and GRS, 0.95 vs. 0.76, 0.69 and 0.61, respectively). The cutoff value with ??30.3% of GAS had sensitivity of 91.8%, specificity of 91.6% and accuracy of 91.3% for differentiating methamphetamine abusers from normal subjects. The potential myocardial function abnormalities can be detected by 3D STE in asymptomatic methamphetamine abusers, and GAS is a good indicator for indentifying methamphetamine abusers from normal population, which can be used to screening and monitor methamphetamine abuse, detect subclinical LV dysfunction, predict potential methamphetamine-related cardiotoxicity, and to initiate early cardioprotective therapy before the onset of overt heart failure in time.     

Robust motion tracking based on adaptive speckle decorrelation analysis of OCT signal

Speckle decorrelation analysis of optical coherence tomography (OCT) signal has been used in motion tracking. In our previous study, we demonstrated that cross-correlation coefficient (XCC) between Ascans had an explicit functional dependency on the magnitude of lateral displacement (δx). In this study, we evaluated the sensitivity of speckle motion tracking using the derivative of function XCC(δx) on variable δx. We demonstrated the magnitude of the derivative can be maximized. In other words, the sensitivity of OCT speckle tracking can be optimized by using signals with appropriate amount of decorrelation for XCC calculation. Based on this finding, we developed an adaptive speckle decorrelation analysis strategy to achieve motion tracking with optimized sensitivity. Briefly, we used subsequently acquired Ascans and Ascans obtained with larger time intervals to obtain multiple values of XCC and chose the XCC value that maximized motion tracking sensitivity for displacement calculation. Instantaneous motion speed can be calculated by dividing the obtained displacement with time interval between Ascans involved in XCC calculation. We implemented the above-described algorithm in real-time using graphic processing unit (GPU) and demonstrated its effectiveness in reconstructing distortion-free OCT images using data obtained from a manually scanned OCT probe. The adaptive speckle tracking method was validated in manually scanned OCT imaging, on phantom as well as in vivo skin tissue.OCIS codes: (170.4500) Optical coherence tomography, (120.5800) Scanners, (030.6140) Speckle, (330.4150) Motion detection     

超声斑点追踪显像技术评价高血压对左室心肌扭转-位移环的影响

5目的运用超声斑点追踪显像(STI)技术构建左室心肌扭转-径向位移环(Loop),探讨心动周期中高血压对心室扭转-位移环的影响并评价高血压患者左室功能的早期改变。方法原发性高血压患者32例和正常人24例,经胸采集心尖水平和心底水平二维图像,运用超声工作站行定量分析,构建左室心肌扭转-径向位移环(Loop),计算心肌扭转角度,径向位移。分析心动周期中扭转与径向位移之间的相关性,比较高血压患者与正常人的扭转峰值、二尖瓣开放时间点(MVO)扭转值、解旋率、收缩期和舒张早期径向位移,同时分析Loop各形态参数。结果①与正常人比较,高血压患者左室扭转峰值增大(18.26±4.2vs13.82±2.7,P<0.001),解旋率减小[(34±7.0)%/msvs(44±11.9)%/ms,P<0.001],差异均有统计学意义。②左室收缩期扭转与径向位移显著线性相关(r=0.97,P<0.05),高血压较正常组Loop收缩期斜率增大(P<0.05)。舒张早期心室解旋约40%,此期径向位移相对较小,二者呈线性相关(r=0.94,P<0.05),Loop图上舒张早期斜率较正常组大(P<0.05)。结论利用STI可以无创性的构建左室扭转-径向位移环。通过分析环的各形态参数,评估高血压患者早期左心功能变化。     

斑点追踪技术评价年龄因素对正常成人右房功能的影响

目的应用斑点追踪(STE)技术评价年龄因素对正常成人右房功能的影响。方法选择146例体检健康者按年龄分为三组:Ⅰ组40例,年龄20~39岁;Ⅱ组55例,年龄40~59岁;Ⅲ组51例,年龄60~80岁。常规超声测量右房长径(RAL)、短径(RAS)及最大面积(RAAmax),三尖瓣口舒张早期峰速(TVE)、舒张晚期峰速(TVA)、三尖瓣环舒张早期速度(TVe’)和舒张晚期速度(TVa’);STE测量右房6节段收缩期应变率(SRs)、舒张早期应变率(SRe)、舒张晚期应变率(SRa),并计算右房收缩期平均应变率(SRs-avg)、舒张早期平均应变率(SRe-avg)、舒张晚期平均应变率(SRa-avg)。结果 RAS、RAAmax随年龄增大而增大,SRs-avg、SRe-avg随年龄增大而减小(均P0.05),且SRs、SRe减小主要位于房间隔;SRa-avg随年龄增大而增大(P0.01),且SRa-avg增大主要位于房间隔。RAAmax与年龄呈正相关(r=0.331,P0.05),SRs-avg、SRe-avg与年龄呈负相关(r=-0.415、-0.227,均P0.05),SRa-avg与年龄呈正相关(r=0.209,P0.05)。结论正常成人右房随年龄增大而增大,右房功能亦随增龄改变,其容量器功能、管道功能减低,泵功能增加,且房间隔受损显著。STE评价正常成人右房功能随年龄改变可行且有效。     

四维斑点追踪联合超声心动图分层应变技术评价不同部位起搏对左心室功能及同步性的影响

目的 应用四维斑点追踪显像(4D-STI)及超声心动图分层应变技术评价右心室不同部位起搏器植入术后左心室收缩功能及同步性.方法 选取2018年12月至2019年10月于中国医学科学院阜外医院住院的双腔起搏器植入术患者100例,并根据起搏部位不同将其分为右心室心尖组(RVAP组)35例、右心室间隔组(RVSP组)35例、...     

Myocardial layer-specific analysis of ischemic memory using speckle tracking echocardiography

The assessment of post-systolic shortening (PSS) by speckle tracking echocardiography allows myocardial ischemic memory imaging. Because the endocardial layer is more vulnerable to ischemia, the assessment of this layer might be useful for detecting ischemic memory. Serial echocardiographic data were acquired from nine dogs with 2 min of coronary occlusion followed by reperfusion. Regional deformation parameters were measured in the risk and normal areas. Using speckle tracking echocardiography, circumferential strain was analyzed in the endocardial, mid-wall, and epicardial layers; and radial strain was analyzed in the inner half, outer half and entire (transmural) layers. In the risk area, peak systolic and end-systolic strain in the circumferential and radial directions significantly decreased during occlusion, but recovered to the baseline levels immediately after reperfusion in all layers. However, circumferential post-systolic strain index (PSI), a parameter of PSS, significantly increased during occlusion, and the significant increases persisted until 20 min after reperfusion in the endocardial and mid-wall layers. Radial PSI tended to increase after reperfusion in the inner half and entire layers but these increases were not significant compared with baseline. In the normal area, systolic strains and PSI in the radial and circumferential directions hardly changed before and after occlusion/reperfusion in all layers. In layer-specific analysis with speckle tracking echocardiography, circumferential PSS in the endocardial and mid-wall layers may be useful for detecting ischemic memory.     

超声二维斑点追踪显像评价健康人左心室扭转-位移环的初步研究

目的 应用超声二维斑点追踪显像技术探讨不同年龄正常成人左室扭转与径向位移的关系.方法 健康成年志愿者121例,按年龄分为青年组(18～45岁)、中年组(46～64岁)和老年组(≥65岁).取胸骨旁左室心尖和心底短轴观对左室各水平旋转及径向位移进行测量分析,计算出左室扭转与左室径向位移,构建左室扭转-位移环,并比较不同年龄组的差别.结果 三组左室心尖部与心底部心肌旋转角度及各节段径向位移曲线随心动周期规律变化.三组左室扭转-位移环均呈"8"字构型.收缩期及等容舒张期左室扭转与径向位移均呈线性相关;随年龄增加,收缩期扭转-位移环的变化斜率明显增加,差异有统计学意义(P＜0.05);与青年组比较,中年组及老年组等容舒张期扭转-位移环的变化斜率均明显增加,差异均有统计学意义(P＜0.05),但中年组与老年组间比较差异无统计学意义(P＞0.05).结论 应用超声二维斑点追踪显像技术可无创性构建左室扭转-位移环,年龄影响收缩期左室扭转-位移环.     

Laser speckle imaging in the spatial frequency domain

Laser Speckle Imaging (LSI) images interference patterns produced by coherent addition of scattered laser light to map subsurface tissue perfusion. However, the effect of longer path length photons is typically unknown and poses a limitation towards absolute quantification. In this work, LSI is integrated with spatial frequency domain imaging (SFDI) to suppress multiple scattering and absorption effects. First, depth sensitive speckle contrast is shown in phantoms by separating a deep source (4 mm) from a shallow source (2 mm) of speckle contrast by using a high spatial frequency of illumination (0.24 mm(-1)). We develop an SFD adapted correlation diffusion model and show that with high frequency (0.24 mm(-1)) illumination, doubling of absorption contrast results in only a 1% change in speckle contrast versus 25% change using a planar unmodulated (0 mm(-1)) illumination. Similar absorption change is mimicked in vivo imaging a finger occlusion and the relative speckle contrast change from baseline is 10% at 0.26 mm(-1) versus 60% at 0 mm(-1) during a finger occlusion. These results underscore the importance of path length and optical properties in determining speckle contrast. They provide an integrated approach for simultaneous mapping of blood flow (speckle contrast) and oxygenation (optical properties) which can be used to inform tissue metabolism.