Measurement of the Doppler Power of Flowing Blood Using Ultrasound Doppler Devices

Measurement of the Doppler power of signals backscattered from flowing blood (henceforth referred to as the Doppler power of flowing blood) and the echogenicity of flowing blood have been used widely to assess the degree of red blood cell (RBC) aggregation for more than 20 y. Many studies have used Doppler flowmeters based on an analogue circuit design to obtain the Doppler shifts in the signals backscattered from flowing blood; however, some recent studies have mentioned that the analogue Doppler flowmeter exhibits a frequency-response problem whereby the backscattered energy is lost at higher Doppler shift frequencies. Therefore, the measured Doppler power of flowing blood and evaluations of RBC aggregation obtained using an analogue Doppler device may be inaccurate. To overcome this problem, the present study implemented a field-programmable gate array-based digital pulsed-wave Doppler flowmeter to measure the Doppler power of flowing blood, in the aim of providing more accurate assessments of RBC aggregation. A clinical duplex ultrasound imaging system that can acquire pulsed-wave Doppler spectrograms is now available, but its usefulness for estimating the ultrasound scattering properties of blood is still in doubt. Therefore, the echogenicity and Doppler power of flowing blood under the same flow conditions were measured using a laboratory pulser–receiver system and a clinical ultrasound system, respectively, for comparisons. The experiments were carried out using porcine blood under steady laminar flow with both RBC suspensions and whole blood. The experimental results indicated that a clinical ultrasound system used to measure the Doppler spectrograms is not suitable for quantifying Doppler power. However, the Doppler power measured using a digital Doppler flowmeter can reveal the relationship between backscattering signals and the properties of blood cells because the effects of frequency response are eliminated. The measurements of the Doppler power and echogenicity of flowing blood were compared with those obtained in several previous studies.     

Simulation of Doppler ultrasound signals for a laminar, pulsatile, nonuniform flow.

A simulation for Doppler ultrasound quadrature signals from pulsatile, nonuniform flow is presented. It is an extension of an earlier simulation presented by Jones and Giddens (1990a) which was valid for laminar, uniform, steady flow and which included the stochastic characteristics introduced by scattering particles which enter and leave the sample volume at random times. Fourier transform and autoregressive spectral analysis techniques are used to compare the simulated signals to Doppler signals collected from an in vitro flow setup. Power spectra, Doppler frequency estimates and standard deviations of these estimates serve as standards of comparison. Results show that the simulation model generates realistic quadrature signals. The study improves the understanding of the physics of the Doppler process and shows that it can be modeled for complex flow conditions. The input parameters of the simulation are the Doppler instrument parameters and flow characteristics. This allows the simulation to be used for transducer design as well as in the study of the applicability of signal analysis techniques to Doppler ultrasound.     

经静脉声学造影剂增强乳腺肿块彩色血流信号的初步研究

本文探讨经静脉声学造影剂对乳腺肿块彩色血流信号的增强作用及鉴别良恶性病变的应用价值。１０例患者中７例为乳腺癌，３例为良性肿块，经静脉注射声学造影剂后，病灶区彩色血流信号显著增强：６例乳腺癌和１例良性肿块病灶内见有片状彩色血流区，血管数增多２～６条；１例直径＜１．０ｃｍ的乳腺癌见有１条彩色血流束；２例良性肿块中１例无彩色信号而另１例仅有１条血管。结果提示：经静脉声学造影剂能显著增强乳腺肿块彩色多普勒血流信号，更准确地反映肿块血供状况；有助于准确鉴别乳腺良、恶性病变。     

Pulsed Doppler ultrasound detection of flow disturbances in arteriosclerosis.

Pulsed Doppler ultrasound blood flow detection has been used in a noninvasive manner to detect arterial abnormalities associated with arteriosclerosis. Sound spectrograms of ultrasound signals obtained from in vitro and animal studies in which flow was disturbed by obstacles placed in the flow stream showed a different distribution of energy over frequency than signals obtained from studies with no flow disturbances. Similar findings were seen clinically. A technique has been developed which can detect disturbed flow patterns resulting from partial occlusion in important superficial arteries (e.g. femoral and carotid) up to 15 cm distal to localized arterial wall abnormalities. Thirty-five arterial examinations of normal and arteriographically abnormal arteries in 12 patients revealed a sensitivity of 83 percent and a specificity of 61 percent. This study suggests that pulsed Doppler ultrasound may be useful as a screening technique for detection of arteriosclerotic lesions in major superficial arteries.     

A simulation of transit time effects in Doppler ultrasound signals

A signal model is proposed which can be used to study frequency extraction techniques for Doppler ultrasound. The signal is based on the physics of the Doppler process and depends on a sliding window used to average a set of independent Gaussian random numbers. This window is related to the shape of the sample volume for the Doppler pulse and depends on the Doppler angle. Simulation results compare favorably with results from flow experiments in terms of the variance of the estimated Doppler shift, the shape of the power spectra and the behavior of the signals with respect to Burg autoregressive power spectra. A potential use of the signal in the study of spectral analysis techniques is presented.     

超声诊断乳腺癌

目的探讨二维超声及彩色多普勒超声在检查乳腺癌中的表现和特征，评价其在诊断乳腺癌中的应用价值。方法回顾性分析135例经手术及病理证实为乳腺癌患者的超声表现：包括二维声像图特征及彩色多普勒表现：肿块内部及周围的血供情况，血流峰值速度和阻力指数等血流动力学参数。结果135例乳腺癌中，乳腺浸润性导管癌128例，筛状癌3例，髓样癌1例，小叶癌原位癌2例和纤维腺瘤伴肉瘤变l例。超声所见：135例中超声发现肿块129例，大小为0．2em～3．4era不等，肿块纵横径比大于1占69％（89／129），肿块边界不整齐，约占70％（90／129），2例肿块不明显但局部可见沙粒样钙化点及局部血流信号异常。沙粒样钙化点占52．6％（70／129）；彩色多普勒发现血流信号占79．8％（103／129），频谱多普勒示血流峰值速度（PSV）为18-49ends，阻力指数（RI）为0．67～0．96，RI〉0．7占93．2％（96／103）。超声漏诊4例。结论当彩色多普勒超声在乳腺肿块内部或周围，或异常回声区内探及丰富血流信号，流速曲线显示为高速高阻时，要高度怀疑乳腺癌，彩色多普勒超声在乳腺良恶性肿瘤的诊断与鉴别诊断中发挥重要的作用。     

Arterial Doppler signal simulation by time domain processing

Objective: The study's aim was to develop and test a rapid and simply implemented computer simulation method for Doppler ultrasound signals incorporating mean frequency, bandwidth and signal power variation and vortex simulation. Methods: We describe a computer simulation method for arterial Doppler ultrasound signals based on the application of white noise to a filter with a time-varying impulse response. Results: This method is simple to implement and requires the input of only the mean frequency, spectrum shape and Doppler power variation during the cardiac cycle. Analysis with the short term Fourier transform shows good agreement with theoretical prediction. Conclusion: This simulation method can provide a useful tool for comparison of the performance of Doppler signal processing techniques.     

Color Doppler identification of a pericardial effusion in the fetus.

The aim of the study was to determine whether color Doppler identifies abnormal fluid within the pericardial space of the fetal were referred for heart. Second- and third-trimester fetuses diagnostic ultrasound. The four-chamber view of the fetal heart was imaged with real-time ultrasonography and examined for the presence or absence of separation of the pericardium from the epicardium, which extended from the atrioventricular junction toward the apex of the ventricle. To examine the pericardial space, the color Doppler maximal velocity was set at low Nyquist limits (0.08-0.24 m/s). In each fetus the transducer was angled so that the axis of the interventricular septum was parallel or tangential to the ultrasound beam to optimize the color Doppler recording. The control group consisted of 50 fetuses (16-38 weeks of gestation) who did not demonstrate evidence of pericardial effusion when examined with real-time ultrasound. Second- and third-trimester fetuses were selected from our database who demonstrated a pericardial effusion identified with real-time ultrasound.Color Doppler signals were not identified within the pericardial space in the 50 control fetuses. Fetuses with a pericardial effusion identified with real-time ultrasound demonstrated color Doppler within the pericardial space which was opposite to the direction of blood entering and exiting the ventricles. Color Doppler enhanced the detection of a pericardial effusion in the second-trimester fetus when the axis of the heart was and third-parallel or tangential to the ultrasound beam, which is suboptimal for real-time imaging.Color Doppler provides a new method to identify a pericardial effusion in the fetus during the second and third trimesters of pregnancy and complements the real-time examination.     

A double beam doppler ultrasound method for quantitative blood flow velocity measurement

A method for measuring the absolute blood flow velocity waveform is reported. Two independent beams of ultrasound illuminate a vessel simultaneously, producing complementary Doppler signals. The two Doppler frequency shift signals are processed by subtraction and addition at the receiver. The optimum probe position where blood flow velocity is detected can be found as the position where the subtractor output reaches zero. At this position the blood flow velocity is the output from the adder. By this means the influence of the angle between the probe and blood flow is eliminated so that a quantitative measurement is obtained. Both in vitro and clinical results are reported.     

Ultrasonographic Imaging Features of Female Urethral and Peri-urethral Masses: A Retrospective Study of 95 Patients

The aim of this study was to assess the imaging features of urethral and peri-urethral masses on transvaginal or transperineal ultrasound (US) in a cohort of 95 women. In this retrospective study, medical records of 95 female patients with 98 asymptomatic or symptomatic urethral and peri-urethral masses were retrospectively reviewed. Data regarding patient demographic characteristics, symptoms, signs, imaging features on 2-D and 3-D transvaginal or transperineal US, diagnostic tests and physical and intra-operative findings were extracted. The US imaging features and clinicopathologic characteristics of each urethral or peri-urethral mass were compared. On ultrasound, 39 masses (in 39 patients) were diagnosed as urethral diverticula, which manifested mostly as complex cystic masses (24/39, 61.5%); 35 masses (in 33 patients) were diagnosed as para-urethral cysts, which manifested mostly as simple cystic masses (19/35, 54.3%); 13 hypo-echoic solid masses (in 12 patients) exhibiting blood flow signals on color Doppler imaging were diagnosed as urethral leiomyomas; hypo-echoic or heterogeneous solid masses (in 8 patients) exhibiting blood flow signals on color Doppler imaging were diagnosed as urethral caruncles, including one complicated by malignant transformation; solid masses with mixed echogenicity (in 2 patients) exhibiting blood flow signals on color Doppler imaging were diagnosed as urethral squamous cell carcinoma or adenocarcinoma, and a hypoechoic solid mass (in one patient) with blood-flow signals on color Doppler imaging was diagnosed as urethral condyloma associated with human papillomavirus infection. This study confirmed transvaginal or transperineal 2-D and 3-D ultrasonography to be a valid, non-invasive, cost-effective diagnostic modality for the differential diagnosis of urethral and periurethral masses.     

颈动脉体瘤的彩色多普勒超声诊断

用彩色多普勒超声对２６例共２７个颈动脉体瘤进行了研究分析，结果显示颈动脉体瘤在Ｂ型超声上主要表现为有管道的低回声，位于颈动脉分叉处，颈内外动脉间距增大，但其诊断符合率仅为７４％。彩色多普勒应用则显示瘤体内有丰富彩色血流，呈分枝、网状，脉冲多普勒显示多为动脉血流，呈低速低阻型频谱，诊断符合率可达９６％。因此，彩色多普勒超声对颈动脉体瘤的诊断有很大实用价值。     

彩色多普勒血流显像评价肾癌的血管性——一种新的超声造影剂的应用价值

目的：评价超声造影剂利声显对彩超检测肾细胞癌血流状况的增强效应,并探讨其临床应用价值。资料与方法：应用彩色多普勒血流显像检查１９例（个）肾细胞癌,均经手术病理证实,经周围静脉注射超声造影剂利声显（ＳＨＵ５０８Ａ）,浓度３００ｍｇ／ｍｌ,平均注射剂量７９ｍｌ。观察注射前后瘤内血流信号显像情况。结果：超声造影前１９个肾癌彩超显示４个无血流信号,１１个周边部分环绕血流,４个瘤周瘤内见散在点状、短条状血流;超声造影后,１９个肾癌瘤内血流信号均增强,１６／１９（８４．２１％）明显增强,３／１９（１５．７９％）轻度增强,增强效应主要表现为血流信号明显增多,分布区域增大,血管显示段延长,分枝更清晰完整。结论：超声造影剂利声显能显著增强肾细胞癌内彩色多普勒血流信号,更完整显示肾癌的血管形态、分布等,明显改善彩超对肾癌血供的评价,对肾肿瘤诊断有重要的临床应用价值。     

Chronic tuberculous epididymitis: color Doppler US findings with histopathologic correlation

BACKGROUND: The aim of this study was to determine the color Doppler features of tuberculous epididymitis and to correlate these findings with histopathologic findings. METHODS: Color Doppler ultrasound (US) findings of 12 histopathologically proven tuberculous epididymitis and tuberculous epididymo-orchitis in 11 consecutive patients were retrospectively analyzed. Color Doppler US findings of tuberculous epididymitis were correlated with histopathologic findings. RESULTS: Color Doppler US findings of tuberculous epididymitis demonstrated no blood flow in the epididymal lesions except for focal linear or spotty flow signals in the peripheral portion. These findings correlated well with pathologic findings; the central portion of the epididymal lesions demonstrated granulomas with caseation necrosis, and the peripheral portion of the epididymal lesions had several medium to small vessels. CONCLUSIONS: Color Doppler US may be helpful for differential diagnosis of tuberculous epididymitis and non-tuberculous epididymitis.     

Three-dimensional (3D) and 4D color Doppler fetal echocardiography using spatio-temporal image correlation (STIC).

OBJECTIVE: Color Doppler echocardiography is used to visualize three transverse planes: the four-chamber, five-chamber, and three vessels and trachea views. Color Doppler spatio-temporal image correlation (STIC) is a new three-dimensional (3D) technique allowing the acquisition of a volume of data from the fetal heart that is displayed as a cineloop of a single cardiac cycle. The aim of the study was to examine the potential of color Doppler STIC to evaluate normal and abnormal fetal hearts. METHODS: This prospective study included 35 normal fetuses and 27 fetuses with congenital heart defects (CHD) examined between 18 and 35 weeks of gestation. Volume acquisition was achieved by initiating the image capture sequence from the transverse four-chamber view. Volumes were stored for later offline evaluation using a personal computer-based workstation in a multiplanar mode and as spatial volume rendering. RESULTS: Successful acquisition was possible in all 62 cases. The three planes could be demonstrated in 31/35 healthy fetuses and in 24/27 fetuses with CHD. Spatial volume rendering was attempted in 18 fetuses with CHD. In the four normal fetuses with inadequate visualization using color Doppler STIC, the region of interest was perpendicular to the ultrasound beam. In two fetuses with CHD inadequate visualization was related to an enlarged heart in late gestation, in which the entire cardiac volume could not be acquired. The third case was an 18-week fetus with complex CHD and transposed great vessels in which artifacts were related to confluent color signals as a result of low resolution in the reconstructed plane. CONCLUSIONS: STIC in combination with color Doppler ultrasound is a promising new tool for multiplanar and 3D/4D rendering of the fetal heart. Limitations may be found later in gestation in fetuses with large hearts and early in gestation as a result of low discrimination of signals. In addition, insonation perpendicular to the structure of interest does not image color Doppler signals and should be avoided during acquisition.     

Methods to evaluate the sample volume of pulsed Doppler systems

The spatial resolution of a pulsed Doppler system heavily depends on both the characteristics of the ultrasound transducer and the processing circuitry. The local characteristics of the ultrasound beam give the lateral sample function while the way the signals are processed affects the axial shape of the sample volume. A simple way to explore the size of the sample volume is the employment of a running string target. However, the detected Doppler signals will be the sum of all the Doppler signals returned by the string along its course through the sample volume. Therefore, it will be complicated to separate the axial and lateral contribution to the actual size of the sample volume. A scanning system capable of visualizing the cross-sectional distribution of the ultrasound intensity allows the assessment of the sample sensitivity in lateral direction. A single vibrating point target enables the exploration of both the axial and lateral sampling function. The latter approach is especially suited to evaluate routinely the spatial performance of pulsed Doppler systems in clinical practice.     

A real-time autoregressive spectrum analyzer for Doppler ultrasound signals

A system based on a digital signal processor and a microcomputer has been programmed to estimate the maximum entropy autoregressive (AR) power spectrum of ultrasonic Doppler shift signals and display the results in the form of a sonogram in real-time on a computer screen. The system, which is based on a TMS 320C25 digital signal processor chip, calculates spectra with 128 frequency components from 64 samples of the Doppler signal. The samples are collected at a programmable rate of up to 40.96 kHz, and the computation of each spectrum takes typically 3.2 ms. The feasibility of on-line AR spectral estimation makes this type of analysis an attractive alternative to the more conventional fast Fourier transform approach to the analysis of Doppler ultrasound signals.     

Vascularity of gastric carcinoma: evaluation using color Doppler ultrasonography

Purpose The purpose of this study was to investigate the vascularity of primary gastric cancer lesions using color Doppler ultrasonography.Methods We used color Doppler ultrasonography to study 78 patients with gastric cancer detected on B-mode ultrasonographic examination and 14 patients without gastric tumors but with a slightly thickened gastric wall that was also detected on B-mode ultrasound. The color Doppler signals of the gastric lesions were graded as (–), no color signals; (+), slight increase in number of color signals; and (++), an obvious increase in number of color signals. The vessel area outside the tumor area in the microscopic pathological specimens was also calculated.Results The color signals of 13 (18%) of the 71 gastric cancer patients were graded (–); those of 14 (20%) patients were graded (+); and those of 44 (62%) patients were graded (++). The color signals for 9 (65%) of 14 patients without gastric tumors were graded (–); those of 4 (28%) patients were graded (+), and those of 1 patient (7%) were graded (++). These differences were significant (P = 0.0002). The vessel count ratio in the microscopic pathologic specimens was also significantly higher in patients with an increased number of color signals than in those without an increased number of color signals (P = 0.002).Conclusion Color Doppler ultrasound showed increased vascularity in the gastric cancers in most of the subjects (82%, 58/71). Furthermore, color Doppler ultrasound also showed no increase in vascularity in most subjects (65%, 9/14) whose B-mode ultrasonograms showed thickened gastric walls but who did not have gastric cancer. Thus, color Doppler imaging may prove useful as a screening modality for gastric cancer.     

Prenatal diagnosis of placenta previa accreta by transabdominal color Doppler ultrasound.

OBJECTIVE: The aim of this study was to evaluate the efficacy of transabdominal color Doppler ultrasound in diagnosing placenta previa accreta. DESIGN: Eighty patients with persistent placenta previa underwent transabdominal B-mode and color Doppler ultrasound evaluation in the second and third trimesters because they had a high risk of placenta accreta. Color Doppler imaging criteria used included diffuse intraparenchymal placental lacunar flow; focal intraparenchymal placental lacunar flow; bladder-uterine serosa interphase hypervascularity; prominent subplacental venous complex; and loss of subplacental Doppler vascular signals. The color Doppler images were interpreted prospectively for signs of placenta previa accreta according to the exhibited color Doppler sonographic features. RESULTS: Sixteen of the 80 patients exhibited characteristic color Doppler imaging patterns highly specific for placenta accreta according to the preceding criteria, and 14 of these had histopathological proof of placenta accreta. Two patients had false-positive color Doppler imaging evidence mistaken for interphase hypervascularity caused by bladder varices. Thirteen patients underwent hysterectomy in the group suspicious for accreta. Of the 64 patients with negative color Doppler imaging results, three had placenta accreta, while two required cesarean hysterectomy; the remaining patient underwent uterine artery ligation for bleeding from the lower uterine segment. The sensitivity of color Doppler imaging in the diagnosis of placenta previa accreta was 82.4% (14/17) and the specificity was 96.8% (61/63). The positive and negative predictive values were 87.5% (14/16) and 95.3% (61/64), respectively. CONCLUSIONS: Variable vascular morphological patterns of placenta previa accreta were exhibited and categorized by transabdominal color Doppler sonography in the antenatal period. The identification of these specific vascular patterns had a positive impact on the peripartum clinical management of the affected patients.     

MP3 compression of Doppler ultrasound signals

The effect of lossy, MP3 compression on spectral parameters derived from Doppler ultrasound (US) signals was investigated. Compression was tested on signals acquired from two sources: 1. phase quadrature and 2. stereo audio directional output. A total of 11, 10-s acquisitions of Doppler US signal were collected from each source at three sites in a flow phantom. Doppler signals were digitized at 44.1 kHz and compressed using four grades of MP3 compression (in kilobits per second, kbps; compression ratios in brackets): 1400 kbps (uncompressed), 128 kbps (11:1), 64 kbps (22:1) and 32 kbps (44:1). Doppler spectra were characterized by peak velocity, mean velocity, spectral width, integrated power and ratio of spectral power between negative and positive velocities. The results suggest that MP3 compression on digital Doppler US signals is feasible at 128 kbps, with a resulting 11:1 compression ratio, without compromising clinically relevant information. Higher compression ratios led to significant differences for both signal sources when compared with the uncompressed signals.     

超声造影剂在正常人肝脏中的应用研究

经外周静脉注射，超声造影剂通过肺循环达到全身脏器和组织增强多普勒血流信号是造影剂的最新发展。我们运用Levovist对20例上常人肝脏进行了前瞻性研究，其结果显示19例多普勒血流信号增强达到Ⅲ级，占95％，1例达到Ⅱ级；平均增强开始时间、峰值出现时间和持续时间分别为14．1秒、23．6秒和167.1秒。有5例出现二维声像图增强，6例门静脉内出现点状强问声。超声造影剂能够有效增强彩色多普勒信号，有助于细小血管的显于，具有很高的潜在价值，将推动超声诊断水平的提高。