定量组织速度成像心肌速度梯度评价胸部放疗患者左心室心肌局部舒张功能的研究

目的：探讨定量组织速度成像（QTVI）心肌速度梯度技术在评价胸部放疗患者左室局部舒张功能方面的临床应用价值。方法：应用QTVI技术离线分析40例胸部肿瘤放疗患者和20例正常人左心室各心肌节段长轴和短轴方向上的速度曲线，并将40例胸部肿瘤放疗患者按照放疗进程分为二组：A组：2.7～3.3周、照射剂量30～40Gy；B组：4.1～5.5周、照射剂量50～60Gy；测量舒张早期峰值速度（Ve）和舒张晚期峰值速度（Va），并计算长轴和短轴方向上舒张早期及晚期心肌速度梯度MVG1、MVG2和MVG3等参数。结果：①A组和B组左室二尖瓣口血流速率（E/A）比值较对照组减低（P＜0.05）；B组的E/A比值较A组减低（P＜0.05）。②A组和B组前壁、前间隔、后壁各节段MVG1、MVG2及MVG3均较对照组明显减低（P＜0.05）；B组前壁、前间隔、后壁各节段MVG1、MVG2及MVG3较A组减低（P＜0.05）；A组和B组侧壁、后间隔各节段MVG1、MVG2及MVG3较对照组略减低但差异无显著性（P＞0.05）；下壁各节段MVG1、MVG2及MVG3在3组之间比较，差异均无显著性（P＞0.05）。结论：胸部放疗患者左心室长轴和短轴方向局部心肌舒张功能存在一定程度的降低；心肌速度梯度可以对其进行正确评价，为局部心肌舒张功能的估测提供了一个新的量化指标。     

应用心肌速度梯度评价胸部放疗患者早期心肌损伤的临床研究

目的探讨心肌速度梯度在评价胸部放疗患者早期心肌损伤的临床价值。方法 40例胸部放疗患者和20例体检健康者为对照组,应用定量组织速度成像技术分析其左室各心肌节段短轴方向上的速度曲线,并将40例胸部放疗患者按照放疗进程分为两组:A组40例,照射2.7～3.3周,照射剂量30～40Gy;B组40例,照射4.1～5.5周,照射剂量50～60Gy。测量心肌各节段内外膜收缩期峰值速度、舒张早期峰值速度和舒张晚期峰值速度,并计算短轴方向上收缩期及舒张早期、晚期心肌速度梯度(MVGS、MVGE和MVGA)。结果对照组、A组、B组前壁、前间隔、后壁各节段MVGS、MVGE及MVGA依次减小,两两组间比较差异均有统计学意义(P<0.05)。结论胸部放疗患者左室短轴方向局部心肌收缩及舒张功能均存在一定程度降低;心肌速度梯度可作为一种新方法对其进行评价。     

二维斑点追踪成像技术评价胸部放疗后早期左室短轴收缩功能损伤

目的：应用二维斑点追踪成像技术（2D-STI）定量分析左室短轴收缩功能,评价二维斑点追踪成像技术在检出胸部放疗后对心脏早期损伤方面的应用价值。方法：46例接受胸部放疗的恶性肿瘤患者按照放疗进程分为3组：A组：放疗前（对照组）;B组：放疗时间2.5～3周、照射剂量26～30Gy;C组：放疗时间5～6周、照射剂量50～60Gy。测量左心室基底段、中段短轴方向峰值径向应变（RS）及圆周应变（CS）。结果：①C组前壁、前间隔和后壁各节段的RS和CS较A组明显减低（P<0.01）;C组前壁、前间隔和后壁各节段的RS和CS较B组减低（P<0.05）;B组前壁、前间隔和后壁各节段的RS和CS与A组比较无显著性差异（P>0.05）。②下壁、侧壁和后间隔各节段的RS和CS在各组之间无显著性差异（P>0.05）。结论：研究表明胸部放疗达到一定时间和剂量时,被照心肌组织的RS和CS均比放疗前明显减低,说明已出现心脏局部的收缩功能受损。二维斑点追踪成像技术对评价胸部放疗后的早期心脏损伤具有重要价值。     

应变率成像评价胸部放疗对心脏的早期损伤

目的采用应变率成像(SRI)分析左室壁应变率特点,评价其在胸部放疗对心脏早期损伤方面的应用。方法40例胸部全程放疗患者按照放疗进程分为三组:A组:放疗前1～3天;B组:放疗时间2.5～3周、照射剂量26～30Gy;C组:放疗时间5～6周(放疗结束时)、照射剂量50～60Gy。比较3组常规超声心动图测值及前壁、下壁、前间隔、后壁的基底段及中间段8个位点的收缩期最大应变率(s)、舒张早期最大应变率(e)、房缩期应变率(a),取三个心动周期的平均值。结果C组前壁、前间隔、后壁各节段的s、e较A组明显减低且差异有显著性(P<0.01);B组前壁、前间隔、后壁各节段的s、e较A组略减低但差异无显著性(P>0.05);下壁各节段的s、e在各组之间差异无显著性(P>0.05);C组左室舒张功能(E/A)较A组减低有显著性差异(P<0.01);B组的E/A较A组略减低但无显著性差异(P>0.05)。结论应变率成像可定量分析胸部放疗患者心脏的早期损伤。     

定量组织速度成像评价左乳腺癌患者放疗左心室功能的变化

目的探讨定量组织速度成像（QTVI）技术评价左乳腺癌术后患者放疗左心室功能的变化的价值。 方法35例左乳腺癌术后患者按照放疗进程分为A组（对照组，35例）：放疗前；B组（35例）：放疗时间3周、累积剂量30Gy；C组（35例）：放疗结束，时间5周，累积剂量50Gy。对3组患者心脏进行常规超声测量及心肌各节段QTVI参数测定。 结果C组左室舒张功能（E／A）较A组减低差异具有显著性意义（P＜0．01）；B组常规超声各指标与A组比较差异无显著性意义（P＞0．05）。B组心肌各节段QTVI参数与A组的比较无显著性差异（P＞0．05）。C组二尖瓣环前壁、前间隔的舒张晚期峰值速度（Va）明显增高，与A组比较有显著性差异（P＜0．01），舒张早期峰值速度（Ve）、Ve／Va与A组的比较明显减低（P＜0．01），而C组收缩期峰值速度（Vs）与A组的比较无显著性差异（P＞0．05）；C组二尖瓣环下壁、后壁各指标与A组的比较均无显著性差异（P＞0．05）。 结论QTVI技术可以准确评价左乳腺癌术后放疗患者早期左心室功能的变化。     

速度向量成像技术评价兔急性心肌缺血局部心肌功能的研究

目的建立新西兰大白兔急性心肌缺血的动物模型,应用速度向量成像(VVI)技术分析急性心肌缺血状态下左心室长轴和短轴方向上各节段局部心肌收缩功能的变化特点。方法新西兰大白兔30只,随机分为冠状动脉结扎组和假手术组,于术前和术后30min内行超声心动图检查并采集动态图像,脱机行VVI分析,测量左心室心肌各节段长轴和短轴方向上的VVI参数:收缩期峰值运动速度(Vs)、收缩期峰值应变(Ss)、收缩期峰值应变率(SRs),行统计学分析。结果心肌缺血后,分别与术前及与假手术组比较,长轴方向上,前间隔心尖段与后壁心尖段的Vs明显减低;前间隔中间段、心尖段与后壁心尖段Ss、SRs明显减低,差异均有统计学意义(P<0.05);短轴方向上,前壁、侧壁的基底段,前间隔、前壁、侧壁的中间段和心尖水平的各节段的Vs明显减低;前间隔、前壁、侧壁的基底段,前间隔、前壁、侧壁、后壁的中间段以及心尖水平各节段的Ss、SRs明显减低,差异均有统计学意义(P<0.05)。结论急性心肌缺血后左心室支供血节段及部分相邻节段的长轴及短轴局部心肌收缩功能减低。VVI技术能够客观、准确的检测实验兔心肌长轴和短轴方向上局部运动功能的微小变化,为急性心肌缺血的早期诊断提供了一种新的无创的、可靠的定量工具。     

定量组织速度成像对心肌梗死患者心肌速度梯度的研究

目的 应用定量组织速度成像(QTVI)分析正常人及心肌梗死患者的心肌运动速度及心肌速度梯度(MVG)，探讨MVG评价缺血心肌局部功能的价值。方法 离线分析19例心肌梗死患者和13例正常对照者左室后壁及前室间隔的心肌多普勒速度曲线，分别测量收缩期及舒张早期短轴方向和长轴方向上的心肌运动速度，并计算相应的MVG。结果 心肌梗死时缺血节段在短轴方向上仅前室间隔的心肌速度较正常明显下降，长轴方向上心肌运动速度较正常无明显变化，而短轴方向和长轴方向上MVG均较正常显著降低。结论 MVG是比心肌运动速度更敏感的反映局部心肌缺血的指标。     

心肌速度分布图评价左室局部收缩功能的初步研究

目的应用组织多普勒心肌速度分布图(myocardial velocity profile,MVP)对左室短轴方向局部收缩功能进行评价。方法应用MVP对15例健康志愿者、15例高血压性左室肥厚患者和11例室间隔非对称性肥厚型心肌病患者的室间隔和左室后壁短轴方向的收缩功能进行评价。结果高血压组的室间隔和左室后壁收缩期心肌速度梯度(myocardialvelocity gradient,MVG)显著低于对照组,具有统计学差异[(1.8±0.3)vs(3.6±0.4),P<0.001和(1.9±0.2)vs(5.1±1.2),P<0.001]。肥厚型心肌病组的室间隔和左室后壁收缩期MVG显著低于对照组,具有统计学差异[(1.2±0.4)vs(3.6±0.4),P<0.0001和(2.4±0.6)vs(5.1±1.2),P<0.001]。MVG的降低以肥厚型心肌病组的室间隔最为显著,肥厚型心肌病组的室间隔收缩期MVG低于高血压组,具有统计学差异[(1.2±0.4)vs(1.8±0.3),P<0.01]。高血压组、肥厚型心肌病组和对照组室间隔的MVP均呈近似线性,但肥厚型心肌病组心肌各点速度分布较对照组和高血压组明显分散。结论高血压性左室肥厚患者和肥厚型心肌病患者左室短轴方向局部收缩功能较正常人减低,MVP能精确地反映心肌短轴上各点在心动周期中的运动速度,并可计算出MVG,可作为一种准确评价左室心肌短轴方向局部收缩功能的新方法。     

心肌背向散射积分参数评价左乳腺癌放疗早期心脏损伤

目的探讨心肌背向散射积分(IBS)参数评价左乳腺癌放疗早期心脏损伤的价值。方法35例左侧乳腺癌全程放疗患者按照放疗进程分为A组:放疗前;B组:放疗时间3周、照射剂量30Gy;C组:放疗时间5周、照射剂量50Gy。对3组行心肌校正IBS(IBS%)、IBS周期变化幅度(CVIB)等背向散射积分参数及舒张早期二尖瓣口血流峰值速度/舒张晚期二尖瓣口血流峰值速度(E/A)等常规超声测定。结果C组前壁、前室间隔的IBS%高于A组差异有显著性(P<0.01),CVIB低于A组差异有显著性(P<0.01);C组前壁、前室间隔的IBS%高于B组差异有显著性(P<0.05),CVIB低于B组差异有显著性(P<0.05);C组左室舒张功能(E/A)较A组减低差异有显著性(P<0.01);C组左室舒张功能(E/A)较B组减低差异有显著性(P<0.05);B组各指标与A组比较差异无显著性意义(P>0.05)。结论心肌背向散射积分参数可无创、敏感、客观地评价左侧乳腺癌放疗对心脏的早期损伤。     

应用全方向M型超声心动图评价2型糖尿病患者的左心室局部心肌功能

目的通过应用全方向M型超声心动图技术检测2型糖尿病患者的左心室心肌速度梯度,以了解该技术评价2型糖尿病患者左心室短轴局部心肌功能的可行性。方法正常组50例,2型糖尿病患者50例,存储左心室短轴二尖瓣水平及乳头肌水平心肌运动图像。应用全方向M型超声分析系统,提取各水平前间隔、后间隔、前壁、侧壁、后壁、下壁等节段室壁的M型运动曲线,测量心肌内外膜峰值运动速度及对应的室壁厚度,获得各室壁节段心肌速度梯度。结果 2型糖尿病患者左心室短轴心肌速度梯度均较正常组低,在收缩期和舒张期的二尖瓣水平,前间隔、后间隔、前壁、后壁及下壁在2组间有差异(P<0.05)。在乳头肌水平,前间隔、后间隔和前壁均有差异(P<0.05)。舒张期较收缩期更早出现异常。结论全方向M型超声可以评价左心室短轴局部心肌功能。     

Postprocessing of Velocity Distributions in Real-Time Ultrasonic Color Velocity Imaging

A robust processing scheme is proposed that improves the presentation of 2-dimensional velocity distributions in real-time ultrasonic color velocity images. Essentially, the algorithm is a modification of a first order recursive filter, processing each velocity signal in the spatial distribution separately from the others. It restores the sudden holes and notches in the velocity profiles that occur wherever the observed blood velocity is incidentally close to zero. At the same time, unlike conventional persistence filters, it does not influence any of the true velocity information that is measured. The result is a consistent sequence of color velocity images with smooth transitions between the borders of the consecutive velocity profiles and with an improved definition of the regions containing blood.     

Effect of Velocity Profile Skewing on Blood Velocity and Volume Flow Waveforms Derived From Maximum Doppler Spectral Velocity

Given evidence that fully developed axisymmetric flow may be the exception rather than the rule, even in nominally straight arteries, maximum velocity (V_max) can lie outside the Doppler sample volume (SV). The link between V_max and derived quantities, such as volume flow (Q), may therefore be more complex than commonly thought. We performed idealized virtual Doppler ultrasound on data from image-based computational fluid dynamics (CFD) models of the normal human carotid artery and investigated how velocity profile skewing and choice of sample volume affected V_max waveforms and derived Q variables, considering common assumptions about velocity profile shape (i.e., Poiseuille or Womersley). Severe velocity profile skewing caused substantial errors in V_max waveforms when using a small, centered SV, although peak V_max was reliably detected; errors with a long SV covering the vessel diameter were orientation dependent but lower overall. Cycle-averaged Q calculated from V_max was typically within ±15%, although substantial skewing and use of a small SV caused 10%–25% underestimation. Peak Q derived from Womersley's theory was generally accurate to within ±10%. V_max pulsatility and resistance indexes differed from Q-based values, although the Q-based resistance index could be predicted reliably. Skewing introduced significant error into V_max-derived Q waveforms, particularly during mid-to-late systole. Our findings suggest that errors in the V_max and Q waveforms related to velocity profile skewing and use of a small SV, or orientation-dependent errors for a long SV, could limit their use in wave analysis or for constructing characteristic or patient-specific flow boundary conditions for model studies.     

QTVI评价SLE患者左室舒张功能的临床研究

目的 探讨定量组织速度成像(QTVI)技术在检测系统性红斑狼疮(SLE)患者左室舒张功能损害中的应用价值.方法 20例SLE患者,按有无窦性心动过速分为两组:Ⅰ组13例,心率≤100次/min,平均(83±17)次/min;Ⅱ组7例,心率＞100次/min,平均(134±19)次/min;另选20例正常人作为对照组;测量二尖瓣口血流频谱E峰、A峰及组织多普勒二尖瓣环Ea,计算E/A、E/Ea比值及6个壁瓣环Ea平均值,并与对照组作比较.结果 Ⅰ组常规超声心动图二尖瓣口血流频谱E峰、A峰及E/A比值与对照组比较无明显差异,Ⅱ组E峰较对照组增高QTVI发现Ⅰ组中有4例二尖瓣口血流频谱出现假性正常化,与对照组比较Ea及Ea值降低,E/Ea增高(P＜0.01);Ⅱ组Ea及与对照组比较无明显差异,但E/Ea较对照组增高(P＜0.05).结论 QTVI可为临床检测SLE患者左室舒张功能提供重要的量化指标,其敏感性优于常规超声法;E/Ea可间接反映SLE伴有心动过速患者的左室舒张功能.     

Brain Blood Flow and Velocity

Objective. Because transcranial Doppler sonography (TCD) is unable to measure arterial diameter, it remains unproven whether the changes in cerebral blood velocity it measures are representative of changes in cerebral blood flow (CBF). Our study was designed to compare velocity changes with flow changes measured by two magnetic resonance imaging (MRI) techniques, perfusion MRI and arterial spin labeling (ASL), using flavanol‐rich cocoa to induce CBF changes in healthy volunteers. Methods. We enrolled 20 healthy volunteers aged 62 to 80 years (mean, 73 years). Each was studied at baseline and after drinking standardized servings of cocoa for 7 to 14 days. Results. Changes in middle cerebral artery (MCA) flow by TCD were significantly correlated with changes in perfusion assessed by gadolinium‐enhanced MRI (r = 0.63; P < .03). Measurements with ASL showed a stronger correlation with borderline significance. Conclusions. Changes in flow velocity in the MCA associated with drinking cocoa were highly correlated with changes in CBF measured by the two MRI techniques using the tracer gadolinium and ASL. These results validate Doppler measurements of CBF velocity as representative assessments of CBF.     

In Vivo Blood Velocity Vector Imaging Using Adaptive Velocity Compounding in the Carotid Artery Bifurcation

Visualization and quantification of blood flow are considered important for early detection of atherosclerosis and patient-specific diagnosis and intervention. As conventional Doppler imaging is limited to 1-D velocity estimates, 2-D and 3-D techniques are being developed. We introduce an adaptive velocity compounding technique that estimates the 2-D velocity vector field using predominantly axial displacements estimated by speckle tracking from dual-angle plane wave acquisitions. Straight-vessel experiments with a 7.8-MHz linear array transducer connected to a Verasonics Vantage ultrasound system revealed that the technique performed with a maximum velocity magnitude bias and angle bias of –3.7% (2.8% standard deviation) and –0.16° (0.41° standard deviation), respectively. In vivo, complex flow patterns were visualized in two healthy and three diseased carotid arteries and quantified using a vector complexity measure that increased with increasing wall irregularity. This measure could potentially be a relevant clinical parameter which might aid in early detection of atherosclerosis.     

Quantification of Ultrasound Correlation‐Based Flow Velocity Mapping and Edge Velocity Gradient Measurement

This study investigated the use of ultrasound speckle decorrelation‐ and correlation‐based lateral speckle‐tracking methods for transverse and longitudinal blood velocity profile measurement, respectively. By studying the blood velocity gradient at the vessel wall, vascular wall shear stress, which is important in vascular physiology as well as the pathophysiologic mechanisms of vascular diseases, can be obtained. Decorrelation‐based blood velocity profile measurement transverse to the flow direction is a novel approach, which provides advantages for vascular wall shear stress measurement over longitudinal blood velocity measurement methods. Blood flow velocity profiles are obtained from measurements of frame‐to‐frame decorrelation. In this research, both decorrelation and lateral speckle‐tracking flow estimation methods were compared with Poiseuille theory over physiologic flows ranging from 50 to 1000 mm/s. The decorrelation flow velocity measurement method demonstrated more accurate prediction of the flow velocity gradient at the wall edge than the correlation‐based lateral speckle‐tracking method. The novelty of this study is that speckle decorrelation‐based flow velocity measurements determine the blood velocity across a vessel. In addition, speckle decor‐relation‐based flow velocity measurements have higher axial spatial resolution than Doppler ultrasound measurements to enable more accurate measurement of blood velocity near a vessel wall and determine the physiologically important wall shear.     

Velocity quantification in magnetic resonance imaging

A variety of methods has been developed for quantitating flow in vivo. These are usually based on the principles of velocity-phase or TOF information. The former allows a point-by-point 2D image of velocity, but also has other manifestations involving real-time 1D projections or 1D projections with 1D velocity information (flow zeugmatography). The TOF methods use the in-flow of unsaturated spins into a saturated region (for example) to estimate flow. The concepts, features, and clinical applications of these and other techniques are reviewed in this article.     

Middle Cerebral Artery Peak Systolic Velocity

OBJECTIVE: The aim of this work was to review the use of middle cerebral artery peak systolic velocity (MCA PSV) for the diagnosis of fetal anemia. METHODS: With the use of a computerized database (MEDLINE), articles on the diagnosis of fetal anemia with ultrasonography were reviewed. Other pertinent references were obtained from the references cited in these articles. In addition, my own institution's clinical experience of the past 18 years was reviewed. RESULTS: Several ultrasonographic parameters have been used to diagnose noninvasive fetal anemia. On the basis of robust data, the MCA PSV is the best ultrasonographic parameter used in the management of fetuses at risk for anemia due to different causes. It is also superior to amniocentesis for the diagnosis of fetal anemia in cases of red cell alloimmunization. CONCLUSIONS: Middle cerebral artery peak systolic velocity is effective for diagnosis of noninvasive moderate and severe fetal anemia. This parameter should not yet be considered the global standard of care for diagnosis of fetal anemia because incorrect use by an inexperienced operator may cause more harm than good; however, if there is a reasonably close medical center with sonographers or sonologists trained to assess the MCA PSV, patients at risk for fetal anemia should be referred to this center.