Test signal injection for Doppler systems

Objective: To evaluate the performance of continuous and pulsed Doppler systems a test signal generator has been developed, simulating an ultrasound radio frequency signal, to be injected by induction into the front-end of an ultrasound Doppler system. Unlike for flow rigs the characteristics of the simulated signal are exactly known and under full control of the user, allowing for an objective interpretation of the test results. Methods: Under software control specific signal characteristics, e.g. ultrasound carrier frequency, clutter frequency, amplitude of clutter signal with respect to Doppler signal amplitude, Doppler signal-to-noise ratio, mean Doppler frequency, shape and width of the Doppler spectral distribution, and its time-dependent behavior can be set and varied. Results: A software package was developed to manipulate the relevant characteristics of the radio frequency signal and to drive a PC compatible plug-in card for signal generation. To illustrate the applicability of the Doppler signal generator some specific examples will be discussed. Conclusion: The proposed test signal generator allows for a variety of Doppler test procedures under controlled and realistic conditions.     

腹壁子宫内膜异位症的彩色多普勒超声表现和诊断价值

目的：探讨腹壁子宫内膜异位症的彩色多普勒超声表现和临床价值。方法：对2003年1月~2010年8月我院23例经手术和病理证实的腹壁内膜异位症的彩色多普勒超声图像表现进行回顾性分析。结果：二维声像图表现为腹壁切口处探及边界欠清晰、形态不规则、内部不均质的低回声肿块,无包膜回声,边缘类似“伪足状”浸润。肿块有经前期增大,回声减弱;经期增大相对明显,回声呈不均匀增强或可见不规则小液性暗区;经期后缩小,回声略增强的特点。彩色多普勒表现为19例肿块内无明显血流信号,4例内部可见少许星点状血流信号,但周边均显示点状血流信号。脉冲多普勒可见动脉频谱,呈低速高阻型,但不易采集到连续、完整的理想频谱。结论：密切结合病史及临床表现,彩色多普勒超声能够对腹壁子宫内膜异位症作出明确诊断,从而对临床病灶的彻底清除具有重要的指导价值;而且具有诊断迅速、可靠、无创伤、操作简便、可重复性强等优势,因此彩色多普勒超声已成为临床首选的最佳检查方法。     

An analytical study of Doppler ultrasound systems

The past theoretical contributions in Doppler ultrasonic imaging have borrowed heavily from the electromagnetic case. In these contributions, most points of departure between the ultrasonic and electromagnetic cases were taken care of by heuristic incorporation of factors in the derived formulas. A theory is presented that is more complete in the sense that it specifically accounts for the diffracted fields of the transducer aperture (assumed to be a source of a Gaussian focussed beam), the interaction of these fields with the scattering sites, and the interaction of the transducer aperture with the back scattered fields. The theoretical formulation was used to perform a series of computer simulation studies on Doppler ultrasound. The control afforded by the theory over different parameters of the system has allowed us to study the effect of the different signal bandwidths, tissue attenuation constants, and the role of transducer design in the ultrasound Doppler systems.     

超声造影剂增强肝血管瘤彩色血流信号的临床研究

目的　探讨肝血管瘤经静脉声学造影增强后的彩色多普勒表现。方法　对 43例肝血管瘤患者(共 5 2个瘤结节 )行经静脉声学造影检查 ,观察造影前后瘤结节内彩色血流信号变化。结果　造影增强后 ,瘤体彩色血流信号检出率显著提高 ,由造影前的 5 5 .8%升高到 90 .4%。瘤体彩色血流信号呈细小点状者 9个 (占17.3 %) ,呈条带状者 2 0个 ( 3 8.4%) ,呈“半月状”者 13个 ( 2 5 .0 %) ,呈“弥漫状”者 5个 ( 9.6%) ,另 5个瘤体无彩色血流信号 ( 10 .6%) ;当增大造影剂剂量至 0 .0 15～ 0 .0 2ml/kg时 ,正常肝组织彩色血流信号增多 ,呈“火海征” ,而瘤体内仍无彩色血流 ,呈“孤岛征”。增强效果 :0级 5个 ,I级 2 9个 ,II级 18个。整个过程持续 2 5 0～ 2 90s ,平均 ( 2 61.6± 2 0 .2 )s。结论　经静脉声学造影能提高肝血管瘤彩色血流信号检出率 ,并获得更为丰富的血流信息 ,这将有助于肝血管瘤的准确诊断     

Towards ultrasound cardiac image segmentation based on the radiofrequency signal

In echocardiography, the radio-frequency (RF) image is a rich source of information about the investigated tissues. Nevertheless, very few works are dedicated to boundary detection based on the RF image, as opposed to envelope image. In this paper, we investigate the feasibility and limitations of boundary detection in echocardiographic images based on the RF signal. We introduce two types of RF-derived parameters: spectral autoregressive parameters and velocity-based parameters, and we propose a discontinuity adaptive framework to perform the detection task. In classical echographic cardiac acquisitions, we show that it is possible to use the spectral contents for boundary detection, and that improvement can be expected with respect to traditional methods. Using the system approach, we study on simulations how the spectral contents can be used for boundary detection. We subsequently perform boundary detection in high frame rate simulated and in vivo cardiac sequences using the variance of velocity, obtaining very promising results. Our work opens the perspective of a RF-based framework for ultrasound cardiac image segmentation and tracking.     

多层螺旋CT与Doppler超声对颈动脉壁层厚度的对比性研究

目的:探讨多层螺旋CT血管造影(MDCTA)和彩色多普勒超声(CD-US)在检测颈总动脉壁厚度(CAWT)和颈总动脉内膜-中层厚度(IMT)中的相关性和一致性.方法:应用MDCTA和CD-US分别对38例受试者颈总动脉的CAWT和IMT进行检测,用Pearson直线相关分析比较CAWT和IMT的相关性,用Bland-Altman分析比较两者的一致性.结果:MDCTA测量的颈总动脉CAWT为(0.87±0.18)mm,CD-US测量的颈总动脉IMT为(0.85±0.16)mm,两者比较无统计学差异,有高度相关性,相关系数为0.958,P＜0.01,Bland-Altman分析两者间存在良好一致性,偏倚为0.026 mm,一致性界限为-0.023 ～ 0.075.结论:MDCTA和CD-US在检测颈总动脉CAWT和IMT时存在良好的相关性和一致性,MDCTA可以替代CD-US,作为一种评价颈动脉早期粥样硬化的更加客观全面的新方法.     

Accuracy of spectral Doppler flow and tissue velocity measurements in ultrasound systems

Blood and tissue velocity are measured and analysed in cardiac, vascular and other applications of diagnostic ultrasound (US). An error in system calibration is a potential risk for misinterpretation of the measurements. To determine the accuracy in velocity calibration, we tested three common commercial US systems using a Doppler string phantom. We tested pulsed and continuous-wave Doppler modes for velocities relevant to both cardiac blood flow and tissue-velocity estimation. The US systems were tested with settings and transducers commonly used in cardiac applications. One system consistently overestimated velocity by about 5%, whereas the other two systems were quite accurate in velocity estimation. These findings emphasize the importance of continuous quality control of US equipment.     

多普勒超声与超声造影评价兔类风湿性关节炎模型滑膜病变

目的 探讨多普勒超声与CEUS评估兔类风湿性关节炎（RA）模型膝关节滑膜病理改变及早期诊断活动性滑膜炎的价值。方法 将30只新西兰兔随机分为两组,对模型组（n=25）以卵蛋白诱导建立双膝关节RA模型,对照组 （n=5）相应时间点仅注射生理盐水。对两组均于多普勒超声和CEUS检查后进行病理检查。以病理检查为金标准,评价多普勒超声及CEUS对活动性滑膜炎的诊断效能,并分析多普勒超声血流分级、CEUS增强程度分级与滑膜炎病理评分的相关性。结果 模型组23只兔建模成功,46个膝关节均出现不同程度红肿,模型组多普勒超声与CEUS均可反映滑膜炎症。对照组膝关节均无明显变化。多普勒超声对兔RA模型膝关节活动性滑膜炎的诊断敏感度、特异度、准确率分别为80.56%（29/36）、60.00%（6/10）、76.09%（35/46）;CEUS分别为94.44%（34/36）、90.00%（9/10）、93.47%（43/46）;两种方法的敏感度、特异度、准确率差异均有统计学意义（χ²=6.35、4.25、5.11,P均<0.05）。多普勒超声血流分级（r_s=0.557,P<0.05）、CEUS增强程度分级（r_s=0.715,P<0.01）均与滑膜炎病理评分呈正相关。结论 多普勒超声和CEUS均可反应兔RA模型膝关节滑膜病理改变,CEUS对活动性滑膜炎的诊断效能更优。     

Doppler ultrasound in the neonate

The use of Doppler ultrasound to assess both the changing haemodynamics of the neonatal circulation and the perfusion of the brain is reviewed. The brain is particularly susceptible to both ischaemic and haemorrhagic injury in preterm and asphyxiated infants. However, the unique characteristics of the transitional neonatal circulation, and of the cerebral vasculature, pose considerable problems in the interpretation of Doppler signals from intracranial arteries. A volumetric Doppler method which eliminates some of those problems is discussed. The same method allows full assessment of the cardiovascular status of the newborn infant, including estimation of ductal shunting and left ventricular output. Doppler ultrasound, if used with a full understanding of the inherant assumptions and limitations of the particular methodology, is likely to prove invaluable in investigating pathological cerebral and cardiac vascular events in the newborn.     

Common bile duct wall thickening due to intramural varices diagnosed by colour Doppler ultrasound

Cases of common bile duct (CBD) wall thickening due to varicose dilation of intramural veins consequential to portal vein thrombosis (PVT) are rare and present a considerable differential diagnostic problem, as they can mimic cholangiocarcinoma. In such cases, colour Doppler ultrasound (CD US) is a very valuable diagnostic method. There are only a few reports in literature on CD US findings of collateral circulation in a thickened CBD wall following PVT. A patient with obstructive jaundice, a tumour of the pancreatic head, CBD wall thickening, and pre-existing PVT is presented. CD US demonstrated collateral circulation of the thrombosed portal vein in the thickened wall of the common bile duct, thus ruling out a mass in the CBD. Obstructive jaundice seldom occurs with choledocal varices. In this patient, the bile duct obstruction was due to the carcinoma of the pancreatic head.     

Evaluation of a 1 MHz transducer for transcranial Doppler ultrasound including embolic signal detection

A 1 MHz transducer for use with transcranial Doppler ultrasound may improve the intensity and therefore the detection of embolic signals (ES) and may also reduce the number of absent acoustic windows. A series of studies was performed to investigate its potential benefits. Firstly, ES were detected using a 1 MHz and a 2 MHz transducer both in vitro and in vivo. Secondly, the time taken to identify 100 middle cerebral arteries (MCA) was recorded for both transducers and the best Doppler signal obtained was reviewed off-line and graded for quality. ES were more intense when detected with the 1 MHz compared with the 2 MHz transducer, both in vitro (p <.0001) and in vivo (p <.0001). Of the 100 MCAs studied, 81 had acoustic windows identified with both transducers. The number of acoustic windows detected with one transducer but not the other was the same for both transducers (n = 3). The time taken to identify the MCA was longer with the 1 MHz transducer (p <.0001) and the quality of the signal achieved was poorer (p <.0001). In conclusion, the 1 MHz transducer improved embolic signal intensity but the overall quality of the flow spectrum obtained was poorer with the 1 MHz than with the 2 MHz transducer. A lower frequency transducer of 1 MHz or possibly 1.5 MHz with transcranial Doppler ultrasound may improve the application of embolic signal detection but may not improve the signal for routine measurement of flow velocities.     

布-加综合征的彩色多普勒超声征象分析

目的探讨布-加综合征的彩色多普勒超声征象及其诊断价值。方法回顾性分析55例布-加综合征的彩色多普勒超声表现和血管造影比较。将布加综合征分为3型:肝内型,肝外型和混合型。结果超声结果与血管造影分型一致为50例(肝内型5例,肝外型29例,混合型16例),诊断准确率为90.9%(50/55)。在下腔静脉狭窄或闭塞的病因中,超声提示单纯膜性狭窄17例(血管造影23例);血栓或癌栓性14例(血管造影16例)。彩色多普勒超声诊断肝脾大16例(29.1%),腹水15例(27.3%),侧枝循环45例(81.8%),尾状叶增大18例(32.7%)。结论超声检查能够为布-加综合征提供直接定位定性和间接征象的诊断依据,可作为诊断该疾病首选影像学检查方法。     

Doppler ultrasound recognition of preclinical changes in arterial wall in diabetic subjects: compliance and pulse-wave damping

Doppler ultrasound was used to detect early changes in arteries of the legs by two independent techniques. Pulse-wave velocity was measured to calculate arterial wall compliance and Fourier analysis was used to measure damping of the pulse-wave forms. Ten non-insulin-dependent diabetic men with no clinical evidence of peripheral arterial disease had significantly lower compliance and greater pulse-wave damping than 10 matched nondiabetic control subjects. There was a good correlation between the results for the two different techniques.     

The detection of blood impurities using ultrasound Doppler

The atraumatic detection of blood impurities such as charcoal particles has potential importance in the monitoring of extracorporeal blood flow for hemodialysis systems using carbon slurry in the dialisate and for blood detoxification using carbon columns. It is shown that existing clinical ultrasound Doppler systems can detect carbon particles whose diameter is comparable to that of an erythrocyte in concentrations as low as 1.5 × 10⁻⁶ g/ml in less than one second. It is shown that for particle detection in flow, Doppler systems are more sensitive than pulse echo systems of equivalent resolution by the ratio of the velocity of sound to that of the flow.     

双频谱多普勒超声成像技术评价左心室乳头肌与附着室壁心肌机械力学时空关联性

目的运用双频谱多普勒超声成像技术评价左心室二尖瓣乳头肌与附着室壁心肌机械力学时空关联性。 方法选择2012年5至6月四川省人民医院经体格检查、心电图和超声心动图检查结果无异常,无高血压、心肌梗死、心脏瓣膜疾病及其他心血管疾病相关病史的健康志愿者112名。应用双频谱多普勒超声成像技术于心尖左心室长轴切面或心尖四腔心切面和心尖二腔心切面同步获取左心室二尖瓣前外侧乳头肌（APM）、后内侧乳头肌（PPM）中段及其乳头肌基底部所附着心室壁的心肌组织运动速度频谱,在同一心动周期内同步测量对应两位点心肌组织运动速度收缩期峰值速度（s′）、舒张早期峰值速度（e′）、舒张晚期峰值速度（a′）,以心电图R波峰尖为时间起点,记录其对应达峰时间St、Et、At。采用配对t检验分别比较APM、PPM与其基底段附着室壁心肌组织、APM与PPM的s′、e′、a′、St、Et、At差异;采用Pearson相关分析分析APM、PPM与其基底段附着室壁心肌组织s′、e′、a′、St、Et、At的相关性及APM与PPM的St、Et、At的相关性。 结果与其基底段附着室壁心肌组织比较,APM的e′、a′均较高、s′均较低,且差异均有统计学意义（t值分别为-2.75、7.76、2.65,P均<0.01）;与其基底段附着室壁心肌组织比较,PPM的e′、a′均较高,且差异均有统计学意义（t值分别为11.74、3.31,P均<0.01）;s′的差异无统计学意义。与其基底部附着室壁心肌组织比较,APM、PPM的Et较小,且差异有统计学意义（t值分别为-8.57、-8.36,P均<0.01）;St、At的差异均无统计学意义。与APM比较,PPM的s′较低,St较长,且差异均有统计学意义（t值分别为2.74、-7.34,P均<0.01）;而e′、a′、Et、At差异均无统计学意义。APM与其基底段附着室壁s′、e′、a′均呈显著正相关（r=0.83、0.77、0.66,P均为0.000）;PPM与其基底段附着室壁s′、e′、a′也均呈显著正相关（r=0.86、0.81、0.79,P均为0.000）。APM与其基底段附着室壁St、Et、At均呈显著正相关（r=0.80、0.98、0.98,P均为0.000）;PPM与其基底段附着室壁St、Et、At也均呈显著正相关（r=0.82、0.99、1.00,P均为0.000）。APM与PPM的St、Et、At均呈显著正相关（r=0.34、0.91、0.88,P均为0.000）。 结论左心室APM、PPM与其附着室壁心肌运动状态存在一致的时空变化规律,两者间舒张期和收缩期心肌峰值运动速度存在差异;两组乳头肌间舒张期心肌峰值运动速度和达峰时间具有较高的同步性和相关性,收缩期心肌运动状态存在明显差异。     

A viscoelastic model of arterial wall motion in pulsatile flow: implications for Doppler ultrasound clutter assessment

The existing computational model studies of pulsatile blood flow in arteries have assumed either rigid wall characteristics or elastic arterial wall behavior with wall movement limited to the radial direction. Recent in vivo studies have identified significant viscoelastic wall properties and longitudinal wall displacements over the cardiac cycle. Determining the nature of these movements is important for predicting the effects of ultrasound clutter in Doppler ultrasound measurements. It is also important for developing an improved understanding of the physiology of vessel wall motion. We present an analytically-based computational model based on the Womersley equations for pulsatile blood flow within elastic and viscoelastic arteries. By comparison with published in vivo data of the human common carotid artery as well as uncertainty and sensitivity analyses, it is found that the predicted waveforms are in reasonable quantitative agreement. Either a pressure, pressure gradient or volumetric flow rate waveform over a single cardiac cycle is used as an input. Outputs include the pressure, pressure gradient, radial and longitudinal fluid velocities and arterial wall displacements, volumetric flow rate and average longitudinal velocity. It is concluded that longitudinal wall displacements comparable to the radial displacements can be present and should be considered when studying the effects of tissue movement on Doppler ultrasound clutter.