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Sample records for spectral doppler ultrasound

  1. Adaptive Spectral Envelope Estimation for Doppler Ultrasound.

    PubMed

    Kathpalia, Aditi; Karabiyik, Yucel; Eik-Nes, Sturla; Tegnander, Eva; Ekroll, Ingvild; Kiss, Gabriel; Torp, Hans

    2016-07-07

    Estimation of accurate maximum velocities and spectral envelope in ultrasound Doppler blood flow spectrograms are both essential for clinical diagnostic purposes. However, obtaining accurate maximum velocity is not straightforward due to intrinsic spectral broadening and variance in the power spectrum estimate. The method proposed in this work for maximum velocity point detection has been developed by modifying an existing method - Signal Noise Slope Intersection (SNSI), incorporating in it steps from an altered version of another method called Geometric Method (GM). Adaptive noise estimation from the spectrogram ensures that a smooth spectral envelope is obtained post detection of these maximum velocity points. The method has been tested on simulated Doppler signal with scatterers possessing a parabolic flow velocity profile constant in time, steady and pulsatile string phantom recordings as well as in vivo recordings from uterine, umbilical, carotid and subclavian arteries. Results from simulation experiments indicate a bias of less than 2.5% in maximum velocities when estimated for a range of peak velocities, Doppler angles and SNR levels. Standard deviation in the envelope is low - less than 2% in case of experiments done by varying the peak velocity and Doppler angle for steady phantom and simulated flow; and also less than 2% in case of experiments done by varying SNR but keeping constant flow conditions for in vivo and simulated flow. Low variability in the envelope makes the prospect of using the envelope for automated blood flow measurements possible and is illustrated for the case of Pulsatility Index estimation in uterine and umbilical arteries.

  2. Adaptive Spectral Envelope Estimation for Doppler Ultrasound.

    PubMed

    Kathpalia, Aditi; Karabiyik, Yucel; Eik-Nes, Sturla H; Tegnander, Eva; Ekroll, Ingvild Kinn; Kiss, Gabriel; Torp, Hans

    2016-11-01

    Estimation of accurate maximum velocities and spectral envelope in ultrasound Doppler blood flow spectrograms are both essential for clinical diagnostic purposes. However, obtaining accurate maximum velocity is not straightforward due to intrinsic spectral broadening and variance in the power spectrum estimate. The method proposed in this paper for maximum velocity point detection has been developed by modifying an existing method-signal noise slope intersection, incorporating in it steps from an altered version of another method called geometric method. Adaptive noise estimation from the spectrogram ensures that a smooth spectral envelope is obtained postdetection of these maximum velocity points. The method has been tested on simulated Doppler signal with scatterers possessing a parabolic flow velocity profile constant in time, steady and pulsatile string phantom recordings, as well as in vivo recordings from uterine, umbilical, carotid, and subclavian arteries. The results from simulation experiments indicate a bias of less than 2.5% in maximum velocities when estimated for a range of peak velocities, Doppler angles, and SNR levels. Standard deviation in the envelope is low-less than 2% in the case of experiments done by varying the peak velocity and Doppler angle for steady phantom and simulated flow, and also less than 2% in the case of experiments done by varying SNR but keeping constant flow conditions for in vivo and simulated flow. Low variability in the envelope makes the prospect of using the envelope for automated blood flow measurements possible and is illustrated for the case of pulsatility index estimation in uterine and umbilical arteries.

  3. Doppler ultrasound spectral enhancement using the Gabor transform-based spectral subtraction.

    PubMed

    Zhang, Yu; Zhang, Hong

    2005-10-01

    Most of the important clinical indices of blood flow are estimated from the spectrograms of Doppler ultrasound (US) signals. Any noise may degrade the readability of the spectrogram and the precision of the clinical indiCes, so the spectral enhancement plays an important role in Doppler US signal processing. A new Doppler US spectral enhancement method is proposed in this paper and implemented in three main steps: the Gabor transform is used to compute the Gabor coefficients of a Doppler US signal, the spectral subtraction is performed on the magnitude of the Gabor coefficients, and the Gabor expansion with the spectral subtracted Gabor coefficients is used to reconstruct the denoised Doppler US signal. The different analysis and synthesis windows are examined in the Gabor transform and expansion. The signal-to-noise ratio (SNR) improvement together with the overall enhancement of spectrograms are examined on the simulated Doppler US signals from a femoral artery. The results show the denoising method based on the orthogonal-like Gabor expansion achieves the best denoising performance. The experiments on some clinical Doppler US signals from umbilical arteries confirm the superior denoising performance of the new method.

  4. Acute Effects of Lateral Thigh Foam Rolling on Arterial Tissue Perfusion Determined by Spectral Doppler and Power Doppler Ultrasound.

    PubMed

    Hotfiel, Thilo; Swoboda, Bernd; Krinner, Sebastian; Grim, Casper; Engelhardt, Martin; Uder, Michael; Heiss, Rafael U

    2017-04-01

    Hotfiel, T, Swoboda, B, Krinner, S, Grim, C, Engelhardt, M, Uder, M, and Heiss, R. Acute effects of lateral thigh foam rolling on arterial tissue perfusion determined by spectral Doppler and power Doppler ultrasound. J Strength Cond Res 31(4): 893-900, 2017-Foam rolling has been developed as a popular intervention in training and rehabilitation. However, evidence on its effects on the cellular and physiological level is lacking. The aim of this study was to assess the effect of foam rolling on arterial blood flow of the lateral thigh. Twenty-one healthy participants (age, 25 ± 2 years; height, 177 ± 9 cm; body weight, 74 ± 9 kg) were recruited from the medical and sports faculty. Arterial tissue perfusion was determined by spectral Doppler and power Doppler ultrasound, represented as peak flow (Vmax), time average velocity maximum (TAMx), time average velocity mean (TAMn), and resistive index (RI), and with semiquantitative grading that was assessed by 4 blindfolded investigators. Measurement values were assessed under resting conditions and twice after foam rolling exercises of the lateral thigh (0 and 30 minutes after intervention). The trochanteric region, mid portion, and distal tibial insertion of the lateral thigh were representative for data analysis. Arterial blood flow of the lateral thigh increased significantly after foam rolling exercises compared with baseline (p ≤ 0.05). We detected a relative increase in Vmax of 73.6% (0 minutes) and 52.7% (30 minutes) (p < 0.001), in TAMx of 53.2% (p < 0.001) and 38.3% (p = 0.002), and in TAMn of 84.4% (p < 0.001) and 68.2% (p < 0.001). Semiquantitative power Doppler scores at all portions revealed increased average grading of 1.96 after intervention and 2.04 after 30 minutes compared with 0.75 at baseline. Our results may contribute to the understanding of local physiological reactions to self-myofascial release.

  5. Modern spectral analysis techniques for blood flow velocity and spectral measurements with pulsed Doppler ultrasound.

    PubMed

    David, J Y; Jones, S A; Giddens, D P

    1991-06-01

    Four spectral analysis techniques were applied to pulsed Doppler ultrasonic quadrature signals to compare the relative merits of each technique for estimation of flow velocity and Doppler spectra. The four techniques were 1) the fast Fourier transform method, 2) the maximum likelihood method, 3) the Burg autoregressive algorithm, and 4) the modified covariance approach to autoregressive modeling. Both simulated signals and signals obtained from an in vitro flow system were studied. Optimal parameter values (e.g., model orders) were determined for each method, and the effects of signal-to-noise ratio and signal bandwidth were investigated. The modern spectral analysis techniques were shown to be superior to Fourier techniques in most circumstances, provided the model order was chosen appropriately. Robustness considerations tended to recommend the maximum likelihood method for both velocity and spectral estimation. Despite the restrictions of steady laminar flow, the results provide important basic information concerning the applicability of modern spectral analysis techniques to Doppler ultrasonic evaluation of arterial disease.

  6. Assessment of Spectral Doppler for an Array-Based Preclinical Ultrasound Scanner Using a Rotating Phantom.

    PubMed

    Kenwright, David A; Anderson, Tom; Moran, Carmel M; Hoskins, Peter R

    2015-08-01

    Velocity measurement errors were investigated for an array-based preclinical ultrasound scanner (Vevo 2100, FUJIFILM VisualSonics, Toronto, ON, Canada). Using a small-size rotating phantom made from a tissue-mimicking material, errors in pulse-wave Doppler maximum velocity measurements were observed. The extent of these errors was dependent on the Doppler angle, gate length, gate depth, gate horizontal placement and phantom velocity. Errors were observed to be up to 172% at high beam-target angles. It was found that small gate lengths resulted in larger velocity errors than large gate lengths, a phenomenon that has not previously been reported (e.g., for a beam-target angle of 0°, the error was 27.8% with a 0.2-mm gate length and 5.4% with a 0.98-mm gate length). The error in the velocity measurement with sample volume depth changed depending on the operating frequency of the probe. Some edge effects were observed in the horizontal placement of the sample volume, indicating a change in the array aperture size. The error in the velocity measurements increased with increased phantom velocity, from 22% at 2.4 cm/s to 30% at 26.6 cm/s. To minimise the impact of these errors, an angle-dependent correction factor was derived based on a simple ray model of geometric spectral broadening. Use of this angle-dependent correction factor reduces the maximum velocity measurement errors to <25% in all instances, significantly improving the current estimation of maximum velocity from pulse-wave Doppler ultrasound.

  7. Doppler ultrasound monitoring technology.

    PubMed

    Docker, M F

    1993-03-01

    Developments in the signal processing of Doppler ultrasound used for the detection of fetal heart rate (FHR) have improved the operation of cardiotocographs. These developments are reviewed and the advantages and disadvantages of the various Doppler and signal processing methods are compared.

  8. Adaptive spectral doppler estimation.

    PubMed

    Gran, Fredrik; Jakobsson, Andreas; Jensen, Jørgen Arendt

    2009-04-01

    In this paper, 2 adaptive spectral estimation techniques are analyzed for spectral Doppler ultrasound. The purpose is to minimize the observation window needed to estimate the spectrogram to provide a better temporal resolution and gain more flexibility when designing the data acquisition sequence. The methods can also provide better quality of the estimated power spectral density (PSD) of the blood signal. Adaptive spectral estimation techniques are known to provide good spectral resolution and contrast even when the observation window is very short. The 2 adaptive techniques are tested and compared with the averaged periodogram (Welch's method). The blood power spectral capon (BPC) method is based on a standard minimum variance technique adapted to account for both averaging over slow-time and depth. The blood amplitude and phase estimation technique (BAPES) is based on finding a set of matched filters (one for each velocity component of interest) and filtering the blood process over slow-time and averaging over depth to find the PSD. The methods are tested using various experiments and simulations. First, controlled flow-rig experiments with steady laminar flow are carried out. Simulations in Field II for pulsating flow resembling the femoral artery are also analyzed. The simulations are followed by in vivo measurement on the common carotid artery. In all simulations and experiments it was concluded that the adaptive methods display superior performance for short observation windows compared with the averaged periodogram. Computational costs and implementation details are also discussed.

  9. New adaptive clutter rejection based on spectral analysis for ultrasound color Doppler imaging: phantom and in vivo abdominal study.

    PubMed

    Geunyong Park; Sunmi Yeo; Jae Jin Lee; Changhan Yoon; Hyun-Woo Koh; Hyungjoon Lim; Youngtae Kim; Hwan Shim; Yangmo Yoo

    2014-01-01

    Effective rejection of time-varying clutter originating from slowly moving vessels and surrounding tissues is important for depicting hemodynamics in ultrasound color Doppler imaging (CDI). In this paper, a new adaptive clutter rejection method based on spectral analysis (ACR-SA) is presented for suppressing nonstationary clutter. In ACR-SA, tissue and flow characteristics are analyzed by singular value decomposition and tissue acceleration of backscattered Doppler signals to determine an appropriate clutter filter from a set of clutter filters. To evaluate the ACR-SA method, 20 frames of complex baseband data were acquired by a commercial ultrasound system equipped with a research package (Accuvix V10, Samsung Medison, Seoul, Korea) using a 3.5-MHz convex array probe by introducing tissue movements to the flow phantom (Gammex 1425 A LE, Gammex, Middleton, WI, USA). In addition, 20 frames of in vivo abdominal data from five volunteers were captured. From the phantom experiment, the ACR-SA method provided 2.43 dB (p <; 0.001) and 1.09 dB ( ) improvements in flow signal-to-clutter ratio (SCR) compared to static (STA) and down-mixing (ACR-DM) methods. Similarly, it showed smaller values in fractional residual clutter area (FRCA) compared to the STA and ACR-DM methods (i.e., 2.3% versus 5.4% and 3.7%, respectively, ). The consistent improvements in SCR from the proposed ACR-SA method were obtained with the in vivo abdominal data (i.e., 4.97 dB and 3.39 dB over STA and ACR-DM, respectively). The ACR-SA method showed less than 1% FRCA values for all in vivo abdominal data. These results indicate that the proposed ACR-SA method can improve image quality in CDI by providing enhanced rejection of nonstationary clutter.

  10. Clinical applications of doppler ultrasound

    SciTech Connect

    Taylor, K.J.W.; Burns, P.N.; Well, P.N.T.

    1987-01-01

    This book introduces a guide to the physical principles and instrumentation of duplex Doppler ultrasound and its applications in obstetrics, gynecology, neonatology, gastroentology, and evaluation of peripheral vascular disease. The book provides information needed to perform Doppler ultrasound examinations and interpret the results. An introduction to Doppler physics and instrumentation is followed by a thorough review of hemodynamics, which explains the principles underlying interpretation of Doppler signals. Of special note is the state-of-the-art coverage of new applications of Doppler in recognition of high-risk pregnancy, diagnosis of intrauterine growth retardation, investigation of neonatal blood flow, evaluation of first-trimester pregnancy, and diagnosis of gastrointestinal disease. The book also offers guidelines on the use of Doppler ultrasound in diagnosing carotid disease, deep venous thrombosis, and aorta/femoral disease.

  11. Operator Auditory Perception and Spectral Quantification of Umbilical Artery Doppler Ultrasound Signals

    PubMed Central

    Thuring, Ann; Brännström, K. Jonas; Ewerlöf, Maria; Hernandez-Andrade, Edgar; Ley, David; Lingman, Göran; Liuba, Karina; Maršál, Karel; Jansson, Tomas

    2013-01-01

    Objective An experienced sonographer can by listening to the Doppler audio signals perceive various timbres that distinguish different types of umbilical artery flow despite an unchanged pulsatility index (PI). Our aim was to develop an objective measure of the Doppler audio signals recorded from fetoplacental circulation in a sheep model. Methods Various degrees of pathological flow velocity waveforms in the umbilical artery, similar to those in human complicated pregnancies, were induced by microsphere embolization of the placental bed (embolization model, 7 lamb fetuses, 370 Doppler recordings) or by fetal hemodilution (anemia model, 4 lamb fetuses, 184 recordings). A subjective 11-step operator auditory scale (OAS) was related to conventional Doppler parameters, PI and time average mean velocity (TAM), and to sound frequency analysis of Doppler signals (sound frequency with the maximum energy content [MAXpeak] and frequency band at maximum level minus 15 dB [MAXpeak-15 dB] over several heart cycles). Results We found a negative correlation between the OAS and PI: median Rho −0.73 (range −0.35– −0.94) and −0.68 (range −0.57– −0.78) in the two lamb models, respectively. There was a positive correlation between OAS and TAM in both models: median Rho 0.80 (range 0.58–0.95) and 0.90 (range 0.78–0.95), respectively. A strong correlation was found between TAM and the results of sound spectrum analysis; in the embolization model the median r was 0.91 (range 0.88–0.97) for MAXpeak and 0.91 (range 0.82–0.98) for MAXpeak-15 dB. In the anemia model, the corresponding values were 0.92 (range 0.78–0.96) and 0.96 (range 0.89–0.98), respectively. Conclusion Audio-spectrum analysis reflects the subjective perception of Doppler sound signals in the umbilical artery and has a strong correlation to TAM-velocity. This information might be of importance for clinical management of complicated pregnancies as an addition to conventional Doppler parameters

  12. Doppler Ultrasound: What Is It Used for?

    MedlinePlus

    ... in your neck (carotid artery stenosis) A Doppler ultrasound can estimate how fast blood flows by measuring the rate of change in its pitch (frequency). During a Doppler ultrasound, a technician trained in ultrasound imaging (sonographer) presses ...

  13. Real-time virtual Doppler ultrasound

    NASA Astrophysics Data System (ADS)

    Khoshniat, Mahdieh; Thorne, Meghan L.; Poepping, Tamie L.; Holdsworth, David W.; Steinman, David A.

    2004-04-01

    Doppler ultrasound (DUS) is widely used to diagnose and plan treatments for vascular diseases, but the relationship between complex blood flow dynamics and the observed DUS signal is not completely understood. In this paper, we demonstrate that Doppler ultrasound can be realistically simulated in a real-time manner via the coupling of a known, previously computed velocity field with a simple model of the ultrasound physics. In the present case a 3D computational fluid dynamics (CFD) model of physiologically pulsatile flow a stenosed carotid bifurcation was interrogated using a sample volume of known geometry and power distribution. Velocity vectors at points within the sample volume were interpolated using a fast geometric search algorithm and, using the specified US probe characteristics and orientation, converted into Doppler shifts for subsequent display as a Doppler spectrogram or color DUS image. The important effect of the intrinsic spectral broadening was simulated by convolving the velocity at each point within the sample volume by a triangle function whose width was proportional to velocity. A spherical sample volume with a Gaussian power distribution was found to be adequate for producing realistic Doppler spectrogram in regions of uniform, jet, and recirculation flow. Fewer than 1000 points seeded uniformly within a radius comprising more than 99% of the total power were required, allowing spectra to be generated from high resolution CFD data at 100Hz frame rates on an inexpensive desktop workstation.

  14. The use of colour-coded and spectral Doppler ultrasound in the differentiation of benign and malignant breast lesions.

    PubMed Central

    Peters-Engl, C.; Medl, M.; Leodolter, S.

    1995-01-01

    The aim of this study was to evaluate the role of colour-coded and spectral Doppler sonography to predict the benign or malignant nature of breast lesions. A total of 112 women with mammographically suspicious breast lesions were investigated prior to surgery. Thirty-nine breast carcinomas and 73 benign lesions were evaluated for the resistance index, pulsatility index and the flow velocity. A resistance index of > or = 0.70 was characteristic of malignant tumours with a sensitivity of 82% and a specificity of 81%. The positive predictive value was 70% and the negative predictive value 89%. Doppler sonography offers one possible method for further investigation of patients with mammographic abnormalities. PMID:7819029

  15. Superharmonic microbubble Doppler effect in ultrasound therapy.

    PubMed

    Pouliopoulos, Antonios N; Choi, James J

    2016-08-21

    The introduction of microbubbles in focused ultrasound therapies has enabled a diverse range of non-invasive technologies: sonoporation to deliver drugs into cells, sonothrombolysis to dissolve blood clots, and blood-brain barrier opening to deliver drugs into the brain. Current methods for passively monitoring the microbubble dynamics responsible for these therapeutic effects can identify the cavitation position by passive acoustic mapping and cavitation mode by spectral analysis. Here, we introduce a new feature that can be monitored: microbubble effective velocity. Previous studies have shown that echoes from short imaging pulses had a Doppler shift that was produced by the movement of microbubbles. Therapeutic pulses are longer (>1 000 cycles) and thus produce a larger alteration of microbubble distribution due to primary and secondary acoustic radiation force effects which cannot be monitored using pulse-echo techniques. In our experiments, we captured and analyzed the Doppler shift during long therapeutic pulses using a passive cavitation detector. A population of microbubbles (5  ×  10(4)-5  ×  10(7) microbubbles ml(-1)) was embedded in a vessel (inner diameter: 4 mm) and sonicated using a 0.5 MHz focused ultrasound transducer (peak-rarefactional pressure: 75-366 kPa, pulse length: 50 000 cycles or 100 ms) within a water tank. Microbubble acoustic emissions were captured with a coaxially aligned 7.5 MHz passive cavitation detector and spectrally analyzed to measure the Doppler shift for multiple harmonics above the 10th harmonic (i.e. superharmonics). A Doppler shift was observed on the order of tens of kHz with respect to the primary superharmonic peak and is due to the axial movement of the microbubbles. The position, amplitude and width of the Doppler peaks depended on the acoustic pressure and the microbubble concentration. Higher pressures increased the effective velocity of the microbubbles up to 3 m s(-1), prior to the onset

  16. Superharmonic microbubble Doppler effect in ultrasound therapy

    NASA Astrophysics Data System (ADS)

    Pouliopoulos, Antonios N.; Choi, James J.

    2016-08-01

    The introduction of microbubbles in focused ultrasound therapies has enabled a diverse range of non-invasive technologies: sonoporation to deliver drugs into cells, sonothrombolysis to dissolve blood clots, and blood-brain barrier opening to deliver drugs into the brain. Current methods for passively monitoring the microbubble dynamics responsible for these therapeutic effects can identify the cavitation position by passive acoustic mapping and cavitation mode by spectral analysis. Here, we introduce a new feature that can be monitored: microbubble effective velocity. Previous studies have shown that echoes from short imaging pulses had a Doppler shift that was produced by the movement of microbubbles. Therapeutic pulses are longer (>1 000 cycles) and thus produce a larger alteration of microbubble distribution due to primary and secondary acoustic radiation force effects which cannot be monitored using pulse-echo techniques. In our experiments, we captured and analyzed the Doppler shift during long therapeutic pulses using a passive cavitation detector. A population of microbubbles (5  ×  104-5  ×  107 microbubbles ml-1) was embedded in a vessel (inner diameter: 4 mm) and sonicated using a 0.5 MHz focused ultrasound transducer (peak-rarefactional pressure: 75-366 kPa, pulse length: 50 000 cycles or 100 ms) within a water tank. Microbubble acoustic emissions were captured with a coaxially aligned 7.5 MHz passive cavitation detector and spectrally analyzed to measure the Doppler shift for multiple harmonics above the 10th harmonic (i.e. superharmonics). A Doppler shift was observed on the order of tens of kHz with respect to the primary superharmonic peak and is due to the axial movement of the microbubbles. The position, amplitude and width of the Doppler peaks depended on the acoustic pressure and the microbubble concentration. Higher pressures increased the effective velocity of the microbubbles up to 3 m s-1, prior to the onset of

  17. The leicester Doppler phantom--a digital electronic phantom for ultrasound pulsed Doppler system testing.

    PubMed

    Gittins, John; Martin, Kevin

    2010-04-01

    Doppler flow and string phantoms have been used to assess the performance of ultrasound Doppler systems in terms of parameters such as sensitivity, velocity accuracy and sample volume registration. However, because of the nature of their construction, they cannot challenge the accuracy and repeatability of modern digital ultrasound systems or give objective measures of system performance. Electronic Doppler phantoms are able to make use of electronically generated test signals, which may be controlled precisely in terms of frequency, amplitude and timing. The Leicester Electronic Doppler Phantom uses modern digital signal processing methods and field programmable gate array technology to overcome some of the limitations of previously described electronic phantoms. In its present form, it is able to give quantitative graphical assessments of frequency response and range gate characteristics, as well as measures of dynamic range and velocity measurement accuracy. The use of direct acoustic coupling eliminates uncertainties caused by Doppler beam effects, such as intrinsic spectral broadening, but prevents their evaluation.

  18. The development of a combined b-mode, ARFI, and spectral Doppler ultrasound imaging system for investigating cardiovascular stiffness and hemodynamics

    NASA Astrophysics Data System (ADS)

    Doherty, Joshua R.; Dumont, Douglas M.; Trahey, Gregg E.

    2011-03-01

    The progression of atherosclerotic disease, caused by the formation of plaques within arteries, is a complex process believed to be a function of the localized mechanical properties and hemodynamic loading associated with the arterial wall. It is hypothesized that measurements of vascular stiffness and wall-shear rate (WSR) may provide important information regarding vascular remodeling, endothelial function, and the growth of soft-lipid filled plaques that could help a clinician better diagnose a patient's risk of clinical events such as stroke. To that end, the approach taken in this work was to combine conventional B-mode, Acoustic Radiation Force Impulse (ARFI), Shear Wave Elasticity Imaging (SWEI), and spectral Doppler techniques into a single imaging system capable of simultaneously measuring the tissue displacements and WSR throughout the cardiac cycle and over several heartbeats. Implemented on a conventional scanner, the carotid arteries of human subjects were scanned to demonstrate the initial in vivo feasibility of the method. Two non-invasive ultrasound based imaging methods, SAD-SWEI and SAD-Gated Imaging, were developed that measure ARF-induced on-axis tissue displacements, off-axis transverse wave velocities, and WSR throughout the cardiac cycle. Human carotid artery scans were performed in vivo on 5 healthy subjects. Statistical differences were observed in both on-axis proximal wall displacements and transverse wave velocities during diastole compared to systole.

  19. Applications of Doppler ultrasound in clinical vascular disease

    NASA Technical Reports Server (NTRS)

    Barnes, R. W.; Hokanson, D. E.; Sumner, D. S.; Strandness, D. E., Jr.

    1975-01-01

    Doppler ultrasound has become the most useful and versatile noninvasive technique for objective evaluation of clinical vascular disease. Commercially available continuous-wave instruments provide qualitative and quantitative assessment of venous and arterial disease. Pulsed Doppler ultrasound was developed to provide longitudinal and transverse cross-sectional images of the arterial lumen with a resolution approaching that of conventional X-ray techniques. Application of Doppler ultrasound in venous, peripheral arterial, and cerebrovascular diseases is reviewed.

  20. An audit of a hospital-based Doppler ultrasound quality control protocol using a commercial string Doppler phantom.

    PubMed

    Cournane, S; Fagan, A J; Browne, J E

    2014-05-01

    Results from a four-year audit of a Doppler quality assurance (QA) program using a commercially available Doppler string phantom are presented. The suitability of the phantom was firstly determined and modifications were made to improve the reliability and quality of the measurements. QA of Doppler ultrasound equipment is very important as data obtained from these systems is used in patient management. It was found that if the braided-silk filament of the Doppler phantom was exchanged with an O-ring rubber filament and the velocity range below 50 cm/s was avoided for Doppler quality control (QC) measurements, then the maximum velocity accuracy (MVA) error and intrinsic spectral broadening (ISB) results obtained using this device had a repeatability of 18 ± 3.3% and 19 ± 3.5%, respectively. A consistent overestimation of the MVA of between 12% and 56% was found for each of the tested ultrasound systems. Of more concern was the variation of the overestimation within each respective transducer category: MVA errors of the linear, curvilinear and phased array probes were in the range 12.3-20.8%, 32.3-53.8% and 27-40.7%, respectively. There is a dearth of QA data for Doppler ultrasound; it would be beneficial if a multicentre longitudinal study was carried out using the same Doppler ultrasound test object to evaluate sensitivity to deterioration in performance measurements.

  1. Measurement of Thermal Effects of Doppler Ultrasound: An In Vitro Study

    PubMed Central

    Helmy, Samir; Bader, Yvonne; Koch, Marianne; Tiringer, Denise; Kollmann, Christian

    2015-01-01

    Objective Ultrasound is considered a safe imaging modality and is routinely applied during early pregnancy. However, reservations are expressed concerning the application of Doppler ultrasound in early pregnancy due to energy emission of the ultrasound probe and its conversion to heat. The objective of this study was to evaluate the thermal effects of emitted Doppler ultrasound of different ultrasound machines and probes by means of temperature increase of in-vitro test-media. Methods We investigated the energy-output of 5 vaginal and abdominal probes of 3 ultrasound machines (GE Healthcare, Siemens, Aloka). Two in-vitro test objects were developed at the Center for Medical Physics and Biomedical Engineering, Medical University Vienna (water bath and hydrogel bath). Temperature increase during Doppler ultrasound emission was measured via thermal sensors, which were placed inside the test objects or on the probes’ surface. Each probe was emitting for 5 minutes into the absorbing test object with 3 different TI/MI settings in Spectral Doppler mode. Results During water bath test, temperature increase varied between 0.1 and 1.0°C, depending on probe, setting and focus, and was found highest for spectral Doppler mode alone. Maximum temperature increase was found during the surface heating test, where values up to 2.4°C could be measured within 5 minutes of emission. Conclusions Activation of Doppler ultrasound in the waterbath model causes a significant increase of temperature within one minute. Thermally induced effects on the embryo cannot be excluded when using Doppler ultrasound in early pregnancy. PMID:26302465

  2. Detection of microemboli by transcranial Doppler ultrasound.

    PubMed Central

    Grosset, D G; Georgiadis, D; Kelman, A W; Cowburn, P; Stirling, S; Lees, K R; Faichney, A; Mallinson, A; Quin, R; Bone, I; Pettigrew, L; Brodie, E; MacKay, T; Wheatley, D J

    1996-01-01

    Doppler ultrasound detection of abnormally high-pitched signals within the arterial waveform offers a new method for diagnosis, and potentially for prediction, of embolic complications in at-risk patients. The nature of Doppler "microembolic" signals is of particular interest in patients with prosthetic heart valves, where a high prevalence of these signals is observed. Monitoring the middle cerebral artery with 2-MHz transcranial Doppler ultrasound (TC-2000, Nicolet Biomedical; Warwick, UK), we looked for microemboli signals in 150 patients (95 women and 55 men), and found 1 or more signals during a 30-min recording in 89% of 70 patients with Bjork-Shiley valves (principally monostrut), 54% of 50 patients with Medtronic-Hall valves, and 50% of 30 patients with Carpentier-Edwards valves (p < 0.001, chi 2). In the patients with Bjork-Shiley valves, the mean number of signals per hour was 59 (range, 42-86; 95% confidence interval), which was significantly higher than the mean in patients with Medtronic-Hall and Carpentier-Edwards valves (1.5[range, 0.5-2.5] and 1 [range, 0-5.3], respectively; both p < 0.04, multiple comparisons. Bonferroni correction). In the patients undergoing serial pre- and postoperative studies, the causative role of the valve implant was emphasized. There was no correlation between the number of emboli signals and a prior history of neurologic deficit, cardiac rhythm, previous cardiac surgery, or the intensity of oral anticoagulation, in patients with prosthetic heart valves. In Bjork-Shiley patients, dual (mitral and aortic) valves were associated with more signals than were single valves. In Medtronic-Hall patients, the signal count was greater for valves in the aortic position than it was for valves in the mitral position. Comparative studies of Doppler emboli signals in other clinical settings suggest a difference in composition or size of the underlying maternal between prosthetic valve patients and patients with carotid stenosis. These

  3. Measurement of the Doppler power of flowing blood using ultrasound Doppler devices.

    PubMed

    Huang, Chih-Chung; Chou, Hung-Lung; Chen, Pay-Yu

    2015-02-01

    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

  4. Ultrasound imaging for the rheumatologist. XVII. Role of colour Doppler and power Doppler.

    PubMed

    Iagnocco, A; Epis, O; Delle Sedie, A; Meenagh, G; Filippucci, E; Riente, L; Scirè, C A; Montecucco, C; Bombardieri, S; Grassi, W; Valesini, G

    2008-01-01

    The use of Doppler ultrasound in rheumatology has grown in recent years. This is partly due to the increasing number of rheumatologists who perform US in their daily clinical practise and also to the technological advances of US systems. Both colour Doppler and power Doppler are used to evaluate the degree of intra- and peri-articular soft tissue inflammation. Moreover, Doppler US has been found to be of help in the assessment of vascular pathologies such as the vasculitides. In this review we provide an update of the data regarding the use of colour Doppler and power Doppler in rheumatology.

  5. Real-time and interactive virtual Doppler ultrasound

    NASA Astrophysics Data System (ADS)

    Hirji, Samira; Downey, Donal B.; Holdsworth, David W.; Steinman, David A.

    2005-04-01

    This paper describes our "virtual" Doppler ultrasound (DUS) system, in which colour DUS (CDUS) images and DUS spectrograms are generated on-the-fly and displayed in real-time in response to position and orientation cues provided by a magnetically tracked handheld probe. As the presence of complex flow often confounds the interpretation of Doppler ultrasound data, this system will serve to be a fundamental tool for training sonographers and gaining insight into the relationship between ambiguous DUS images and complex blood flow dynamics. Recently, we demonstrated that DUS spectra could be realistically simulated in real-time, by coupling a semi-empirical model of the DUS physics to a 3-D computational fluid dynamics (CFD) model of a clinically relevant flow field. Our system is an evolution of this approach where a motion-tracking device is used to continuously update the origin and orientation of a slice passing through a CFD model of a stenosed carotid bifurcation. After calibrating our CFD model onto a physical representation of a human neck, virtual CDUS images from an instantaneous slice are then displayed at a rate of approximately 15 Hz by simulating, on-the-fly, an array of DUS spectra and colour coding the resulting spectral mean velocity using a traditional Doppler colour scale. Mimicking a clinical examination, the operator can freeze the CDUS image on-screen, and a spectrogram corresponding to the selected sample volume location is rendered at a higher frame rate of at least 30 Hz. All this is achieved using an inexpensive desktop workstation and commodity graphics card.

  6. Is Doppler ultrasound useful for evaluating gestational trophoblastic disease?

    PubMed Central

    Lin, Lawrence H; Bernardes, Lisandra S; Hase, Eliane A; Fushida, Koji; Francisco, Rossana P V

    2015-01-01

    Doppler ultrasound is a non-invasive method for evaluating vascularization and is widely used in clinical practice. Gestational trophoblastic neoplasia includes a group of highly vascularized malignancies derived from placental cells. This review summarizes data found in the literature regarding the applications of Doppler ultrasound in managing patients with gestational trophoblastic neoplasia. The PubMed/Medline, Web of Science, Cochrane and LILACS databases were searched for articles published in English until 2014 using the following keywords: “Gestational trophoblastic disease AND Ultrasonography, Doppler.” Twenty-eight articles met the inclusion criteria and were separated into the 4 following groups according to the aim of the study. 1 Doppler ultrasound does not seem to be capable of differentiating partial from complete moles, but it might be useful when evaluating pregnancies in which a complete mole coexists with a normal fetus. 2 There is controversy in the role of uterine artery Doppler velocimetry in the prediction of development of gestational trophoblastic neoplasia. 3 Doppler ultrasound is a useful tool in the diagnosis of gestational trophoblastic neoplasia because abnormal myometrial vascularization and lower uterine artery Doppler indices seem to be correlated with invasive disease. 4 Lower uterine artery Doppler indices in the diagnosis of gestational trophoblastic neoplasia are associated with methotrexate resistance and might play a role in prognosis. CONCLUSION: Several studies support the importance of Doppler ultrasound in the management of patients with gestational trophoblastic neoplasia, particularly the role of Doppler velocimetry in the prediction of trophoblastic neoplasia and the chemoresistance of trophoblastic tumors. Doppler findings should be used as ancillary tools, along with human chorionic gonadotropin assessment, in the diagnosis of gestational trophoblastic neoplasia. PMID:26735221

  7. Display of spatially-registered Doppler spectral waveforms and three-dimensional vein graft geometry.

    PubMed

    Leotta, Daniel F; Primozich, Jean F; Henderson, Sara M; Karr, Leni N; Bergelin, Robert O; Beach, Kirk W; Zierler, R Eugene

    2005-10-01

    A method has been developed to display Doppler spectral waveforms in lower extremity vein grafts in conjunction with 3-D vessel geometry. Doppler spectral waveforms and cross-sectional images of the vein graft are collected with a custom 3-D ultrasound imaging system. Computer processing generates a display of the Doppler sample volumes registered in 3-D space with a surface reconstruction of the vein graft lumen. An interactive computer interface displays spectral waveforms at user-selected sites in the graft. Summary displays combining spectral waveforms, maximum velocity and cross-sectional area provide a pictorial record of the state of the vein graft along its full length. The method is demonstrated for two patient studies, each at two time points after graft revisions. The graphic display of both hemodynamics and geometry allows rapid assessment of vein graft changes over time.

  8. Pediatric imaging/doppler ultrasound of the chest: Extracardiac diagnosis

    SciTech Connect

    Huhta, J.C.

    1986-01-01

    In this book the author spells out new diagnostic applications in pediatrics for high resolution cross-sectional ultrasonography, and demonstrates the ways in which Doppler techniques complement the cross-sectional method. This reference presents practical, step-by-step methods for non-invasive ultrasound examination of extra-cardiac anatomy and assessment of vascular blood flow.

  9. Fetal and umbilical Doppler ultrasound in high-risk pregnancies

    PubMed Central

    Alfirevic, Zarko; Stampalija, Tamara; Gyte, Gillian ML

    2014-01-01

    Background Abnormal blood flow patterns in fetal circulation detected by Doppler ultrasound may indicate poor fetal prognosis. It is also possible false positive Doppler ultrasound findings could encourage inappropriate early delivery. Objectives The objective of this review was to assess the effects of Doppler ultrasound used to assess fetal well-being in high-risk pregnancies on obstetric care and fetal outcomes. Search methods We searched the Cochrane Pregnancy and Childbirth Group’s Trials Register (September 2009) and the reference lists of identified studies. Selection criteria Randomised and quasi-randomised controlled trials of Doppler ultrasound for the investigation of umbilical and fetal vessels waveforms in high-risk pregnancies compared to no Doppler ultrasound. Data collection and analysis Two authors independently assessed the studies for inclusion, assessed risk of bias and carried out data extraction. Data entry was checked. Main results Eighteen completed studies involving just over 10,000 women were included. The trials were generally of unclear quality with some evidence of possible publication bias. The use of Doppler ultrasound in high-risk pregnancy was associated a reduction in perinatal deaths (risk ratio (RR) 0.71, 95% confidence interval (CI) 0.52 to 0.98, 16 studies, 10,225 babies, 1.2% versus 1.7 %, numbers needed to treat = 203; 95%CI 103 to 4352). There were also fewer inductions of labour (average RR 0.89, 95% CI 0.80 to 0.99, 10 studies, 5633 women, random effects) and fewer caesarean sections (RR 0.90, 95% CI 0.84 to 0.97, 14 studies, 7918 women). No difference was found in operative vaginal births (RR 0.95, 95% CI 0.80 to 1.14, four studies, 2813 women) nor in Apgar scores less than seven at five minutes (RR 0.92, 95% CI 0.69 to 1.24, seven studies, 6321 babies). Authors’ conclusions Current evidence suggests that the use of Doppler ultrasound in high-risk pregnancies reduced the risk of perinatal deaths and resulted in less

  10. Robust estimation of fetal heart rate variability using Doppler ultrasound.

    PubMed

    Fernando, Kumari L; Mathews, V John; Varner, Michael W; Clark, Edward B

    2003-08-01

    This paper presents a new measure of heart rate variability (HRV) that can be estimated using Doppler ultrasound techniques and is robust to variations in the angle of incidence of the ultrasound beam and the measurement noise. This measure employs the multiple signal characterization (MUSIC) algorithm which is a high-resolution method for estimating the frequencies of sinusoidal signals embedded in white noise from short-duration measurements. We show that the product of the square-root of the estimated signal-to-noise ratio (SNR) and the mean-square error of the frequency estimates is independent of the noise level in the signal. Since varying angles of incidence effectively changes the input SNR, this measure of HRV is robust to the input noise as well as the angle of incidence. This paper includes the results of analyzing synthetic and real Doppler ultrasound data that demonstrates the usefulness of the new measure in HRV analysis.

  11. Simultaneous fetal magnetocardiography and ultrasound/Doppler imaging.

    PubMed

    Zhao, Hui; Chen, Mingli; Van Veen, Barry D; Strasburger, Janette F; Wakai, Ronald T

    2007-06-01

    The difficulty of utilizing multimodality diagnostic imaging techniques for fetal surveillance remains one of the greatest challenges in providing enhanced prenatal care. In this Letter we demonstrate the feasibility of performing fetal magnetocardiography (fMCG) and ultrasound/Doppler imaging simultaneously, using a multichannel SQUID magnetometer and a portable ultrasound scanner. Despite large magnetic interference from the scanner, the implementation of simple noise reduction procedures and appropriate signal processing techniques yielded fMCG recordings of sufficient quality for assessment of fetal heart rate and rhythm. A variation of reference channel filtering, referred to here as synthetic reference channel filtering, was used to reduce nonstationary low-frequency interference. The combination of fMCG and/or fMEG with ultrasound/Doppler offers new possibilities for assessment of fetal well-being and fetal cardiac function.

  12. Compressed Sensing Doppler Ultrasound Reconstruction Using Block Sparse Bayesian Learning.

    PubMed

    Lorintiu, Oana; Liebgott, Herve; Friboulet, Denis

    2016-04-01

    In this paper we propose a framework for using duplex Doppler ultrasound systems. These type of systems need to interleave the acquisition and display of a B-mode image and of the pulsed Doppler spectrogram. In a recent study (Richy , 2013), we have shown that compressed sensing-based reconstruction of Doppler signal allowed reducing the number of Doppler emissions and yielded better results than traditional interpolation and at least equivalent or even better depending on the configuration than the study estimating the signal from sparse data sets given in Jensen, 2006. We propose here to improve over this study by using a novel framework for randomly interleaving Doppler and US emissions. The proposed method reconstructs the Doppler signal segment by segment using a block sparse Bayesian learning (BSBL) algorithm based CS reconstruction. The interest of using such framework in the context of duplex Doppler is linked to the unique ability of BSBL to exploit block-correlated signals and to recover non-sparse signals. The performance of the technique is evaluated from simulated data as well as experimental in vivo data and compared to the recent results in Richy , 2013.

  13. A study of the spectral broadening of simulated Doppler signals using FFT and AR modelling.

    PubMed

    Keeton, P I; Schlindwein, F S; Evans, D H

    1997-01-01

    Doppler ultrasound is used clinically to detect stenosis in the carotid artery. The presence of stenosis may be identified by disturbed flow patterns distal to the stenosis that cause spectral broadening in the spectrum of the Doppler signal around peak systole. This paper investigates the behaviour of the spectral broadening index (SBI) derived from wide-band spectra obtained using autoregressive modelling (AR), compared with the SBI based on the fast-Fourier transform (FFT) spectra. Simulated Doppler signals were created using white noise and shaped filters to analyse spectra typically found around the systolic peak and to assess the magnitude and variance of AR and FFT-SBI for a range of signal-to-noise ratios. The results of the analysis show a strong correlation between the indices calculated using the FFT and AR algorithms. Despite the qualitative improvement of the AR spectra over the FFT, the estimation of SBI for short data frames is not significantly improved using AR.

  14. Simultaneous spatial and spectral mapping of flow using photoacoustic Doppler measurement

    NASA Astrophysics Data System (ADS)

    Sheinfeld, Adi; Gilead, Sharon; Eyal, Avishay

    2010-11-01

    We demonstrate the use of tone-burst excitation and time-gated spectral analysis for photoacoustic Doppler mapping of flow in an unperturbed vessel phantom and in a vessel with a spatially varying lumen. The method, which mimics pulsed Doppler ultrasound, enables simultaneous measurement of axial position and flow as well as complete characterization of the Doppler spectrum over a wide range of mean velocities (3.5 to 200 mm/s). To generate the required optical excitation, a continuous cw laser source followed by an external electro-optic modulator is used. Stenoses at various levels are emulated in a C-flex tube with a flowing suspension of micrometer-scale carbon particles. Two-dimensional maps of spectral content versus axial position at different points along the vessel and for various levels of perturbations demonstrate the potential use of the method for characterization of flow irregularities.

  15. Power Doppler ultrasound appearances of neonatal ischaemic brain injury.

    PubMed

    Steventon, D M; John, P R

    1997-02-01

    Following neonatal ischaemic brain injury, irregular vessels increase in size owing to luxury perfusion. These may be demonstrated by conventional colour flow Doppler (CFD) imaging at the periphery of the infarcted area. We present a case in which power Doppler imaging (PDI) was performed in addition to CFD in a neonate with unexplained seizures and which proved more sensitive than CFD in demonstrating luxury perfusion. Ultrasound appearances were compared with those seen on cranial CT. PDI can be a useful adjunct to conventional CFD examination of the neonatal brain in cerebral infarction.

  16. Effects of transducer, velocity, Doppler angle, and instrument settings on the accuracy of color Doppler ultrasound.

    PubMed

    Stewart, S F

    2001-04-01

    The accuracy of a commercial color Doppler ultrasound (US) system was assessed in vitro using a rotating torus phantom. The phantom consisted of a thin rubber tube filled with a blood-mimicking fluid, joined at the ends to form a torus. The torus was mounted on a disk suspended in water, and rotated at constant speeds by a motor. The torus fluid was shown in a previous study to rotate as a solid body, so that the actual fluid velocity was dependent only on the motor speed and sample volume radius. The fluid velocity could, thus, be easily compared to the color Doppler-derived velocity. The effects of instrument settings, velocity and the Doppler angle was assessed in four transducers: a 2.0-MHz phased-array transducer designed for cardiac use, a 4.0-MHz curved-array transducer designed for general thoracic use, and two linear transducers designed for vascular use (one 4.0 MHz and one 6.0 MHz). The color Doppler accuracy was found to be significantly dependent on the transducer used, the pulse-repetition frequency and wall-filter frequency, the actual fluid velocity and the Doppler angle (p < 0.001 by analysis of variance). In particular, the phased array and curved array were observed to be significantly more accurate than the two linear arrays. The torus phantom was found to provide a sensitive measure of color Doppler accuracy. Clinicians need to be aware of these effects when performing color Doppler US exams.

  17. [The value of Doppler ultrasound studies in threatened premature labor].

    PubMed

    Jörn, H; Funk, A; Fendel, H

    1993-01-01

    95 patients were investigated using Doppler ultrasound to evaluate its usefulness during the clinical management of patients with preterm labor, preterm rupture of membranes and incompetent cervix. Cases with additional pregnancy complications as preeclampsia or intrauterine growth retardation or infection of the amnion or the birth canal were excluded from our study. We examined the umbilical artery and the uterine arteries. Predicting preterm birth we found a sensitivity of 31.4% and a specificity of 70% for the former and a sensitivity of 34.3% and a specificity of 83.3% for the latter. As a result of our investigation we have to conclude that Doppler ultrasound is not able to predict sufficiently reliable preterm birth to use it in clinical management. Normal uterine blood flow in cases with preterm labor seems to indicate birth at term in a high degree.

  18. Adaptive clutter rejection for ultrasound color Doppler imaging

    NASA Astrophysics Data System (ADS)

    Yoo, Yang Mo; Managuli, Ravi; Kim, Yongmin

    2005-04-01

    We have developed a new adaptive clutter rejection technique where an optimum clutter filter is dynamically selected according to the varying clutter characteristics in ultrasound color Doppler imaging. The selection criteria have been established based on the underlying clutter characteristics (i.e., the maximum instantaneous clutter velocity and the clutter power) and the properties of various candidate clutter filters (e.g., projection-initialized infinite impulse response and polynomial regression). We obtained an average improvement of 3.97 dB and 3.27 dB in flow signal-to-clutter-ratio (SCR) compared to the conventional and down-mixing methods, respectively. These preliminary results indicate that the proposed adaptive clutter rejection method could improve the sensitivity and accuracy in flow velocity estimation for ultrasound color Doppler imaging. For a 192 x 256 color Doppler image with an ensemble size of 10, the proposed method takes only 57.2 ms, which is less than the acquisition time. Thus, the proposed method could be implemented in modern ultrasound systems, while providing improved clutter rejection and more accurate velocity estimation in real time.

  19. Sevoflurane Used for Color Doppler Ultrasound Examination in Children.

    PubMed

    Fan, Conghai; Zhang, Fengchao; Huang, Xiaomei; Wen, Cheng; Shan, Chengjing

    2015-05-01

    The objective of this study is to investigate the feasibility of sevoflurane inhalation in pediatric color doppler ultrasound examination. In this study, 30 cases of children under 1 year were selected. They were all I or II levels according to American Society of Anesthesiology. Children with severe cyanotic congenital heart disease or severe pneumonia were excluded. All the children received anesthesia with sevoflurane. The University of Michigan Sedation Scale was assessed and bispectral index (BIS) was recorded before induction (T0), after induction (T1), when maintaining (T2), and when waking-up (T3). Blood pressure and heart rate were monitored during the color doppler ultrasound examination, the time to receive sedation examination and anesthesia recovery time were also recorded. (1) Score for UMSS was zero at T0 and 3 at T1; (2) BIS value was 93.18 ± 2.94 at T0 and decreased to 87.6 ± 3.9 at T1; (3) Blood pressure or heart rate did not decline obviously; (4) The time to receive sedation examination was 46.4 ± 13.1 s and anesthesia recovery time was 7.8 ± 5.3 min. In conclusion, sevoflurane can be used in pediatric color doppler ultrasound examination safely and effectively.

  20. A new clutter rejection algorithm for Doppler ultrasound.

    PubMed

    Cloutier, Guy; Chen, Danmin; Durand, Louis-Gilles

    2003-04-01

    Several strategies, known as clutter or wall Doppler filtering, were proposed to remove the strong echoes produced by stationary or slow moving tissue structures from the Doppler blood flow signal. In this study, the matching pursuit (MP) method is proposed to remove clutter components. The MP method decomposes the Doppler signal into wavelet atoms that are selected in a decreasing energy order. Thus, the high-energy clutter components are extracted first. In the present study, the pulsatile Doppler signal s(n) was simulated by a sum of random-phase sinusoids. Two types of high-amplitude clutter signals were then superimposed on s(n): time-varying low-frequency components, covering systole and early diastole, and short transient clutter signals, distributed within the whole cardiac cycle. The Doppler signals were modeled with the MP method and the most dominant atoms were subtracted from the time-domain signal s(n) until the signal-to-clutter (S/C) ratio reached a maximum. For the low-frequency clutter signal, the improvement in S/C ratio was 19.0 +/- 0.6 dB, and 72.0 +/- 4.5 atoms were required to reach this performance. For the transient clutter signal, ten atoms were required and the maximum improvement in S/C ratio was 5.5 +/- 0.5 dB. The performance of the MP method was also tested on real data recorded over the common carotid artery of a normal subject. Removing 15 atoms significantly improved the appearance of the Doppler sonogram contaminated with low-frequency clutter. Many more atoms (over 200) were required to remove transient clutter components. These results suggest the possibility of using this signal processing approach to implement clutter rejection filters on ultrasound commercial instruments.

  1. Doppler ultrasound and renal artery stenosis: An overview.

    PubMed

    Granata, A; Fiorini, F; Andrulli, S; Logias, F; Gallieni, M; Romano, G; Sicurezza, E; Fiore, C E

    2009-12-01

    Renovascular disease is a complex disorder, most commonly caused by fibromuscular dysplasia and atherosclerotic diseases. It can be found in one of three forms: asymptomatic renal artery stenosis (RAS), renovascular hypertension, and ischemic nephropathy. Particularly, the atherosclerotic form is a progressive disease that may lead to gradual and silent loss of renal function. Thus, early diagnosis of RAS is an important clinical objective since interventional therapy may improve or cure hypertension and preserve renal function. Screening for RAS is indicated in suspected renovascular hypertension or ischemic nephropathy, in order to identify patients in whom an endoluminal or surgical revascularization is advisable. Screening tests for RAS have improved considerably over the last decade. While captopril renography was widely used in the past, Doppler ultrasound (US) of the renal arteries (RAs), angio-CT, or magnetic resonance angiography (MRA) have replaced other modalities and they are now considered the screening tests of choice. An arteriogram is rarely needed for diagnostic purposes only. Color-Doppler US (CDUS) is a noninvasive, repeatable, relatively inexpensive diagnostic procedure which can accurately screen for renovascular diseases if performed by an expert. Moreover, the evaluation of the resistive index (RI) at Doppler US may be very useful in RAS affected patients for predicting the response to revascularization. However, when a discrepancy exists between clinical data and the results of Doppler US, additional tests are mandatory.

  2. An ideal blood mimicking fluid for doppler ultrasound phantoms.

    PubMed

    Samavat, H; Evans, J A

    2006-10-01

    In order to investigate the problems of detecting tumours by ultrasound it is very important to have a portable Doppler flow test object to use as a standardising tool. The flow Doppler test objects are intended to mimic the flow in human arteries. To make the test meaningful, the acoustic properties of the main test object components (tissue and blood mimic) should match closely the properties of the corresponding human tissues, while the tube should ideally have little influence. The blood mimic should also represent the haemodynamic properties of blood. An acceptable flow test object has been designed to closely mimic blood flow in arteries. We have evaluated the properties of three blood mimicking fluid: two have been described recently in the literature, the third is a local design. One of these has emerged as being particularly well matched to the necessary characteristics for in-vitro work.

  3. [Noise and speckle reduction in ultrasound Doppler blood flow spectrograms by using MP-PCNN].

    PubMed

    Li, Haiyan; Ma, Yue; Zhang, Yufeng; Shu, Xinling

    2011-10-01

    To reduce background noise and Dopplar speckle in the spectrogram of ultrasound Doppler blood flow signals, a novel method, called Matching Pursuit with threshold decaying pulse coupled neural network (MP-PCNN), has been proposed. The proposed method used an iterative algorithm, which decomposed the ultrasound Doppler signals into linear expansion of atoms in a time-frequency dictionary by using the Matching Pursuit (MP) for de-noising the ultrasound Doppler signal. Subsequently, a simplified unidirectional pulse coupled neural network was applied to calculate the firing matrix of the denoised spectrogram. The Doppler speckles were located and removed through analyzing and processing the PCNN firing matrix. Experiments were conducted on simulation signals which SNRs were 0dB, 5dB and 10dB. The result showed that the MP-PCNN performed effectively in reducing noise, eliminating Doppler speckles, and achieved better performance than exiting noise and speckle suppression algorithm for Doppler ultrasound blood flow spectrogram.

  4. Real-time numerical simulation of Doppler ultrasound in the presence of nonaxial flow.

    PubMed

    Khoshniat, Mahdieh; Thorne, Meghan L; Poepping, Tamie L; Hirji, Samira; Holdsworth, David W; Steinman, David A

    2005-04-01

    Numerical simulations of Doppler ultrasound (DUS) relying on computational fluid dynamics (CFD) models of nonaxial flow have traditionally employed detailed (but computationally intensive) models of the DUS physics, or have sacrificed much of the physics in the interest of computational or conceptual simplicity. In this paper, we present a compromise between these extremes, with the objective of simulating the essential characteristics of DUS spectrograms in a real-time manner. Specifically, a precomputed pulsatile CFD velocity field is interrogated at some number, N, of discrete points distributed spatially within a sample volume of prescribed geometry and power distribution and temporally within a prescribed sampling window. Intrinsic spectral broadening is accounted for by convolving each of the point velocities with a semiempirical broadening function. Real-time performance is facilitated through the use of an efficient algorithm for interpolating the unstructured CFD data. A spherical sample volume with Gaussian power distribution, N = 1000 sampling points, and quadratic broadening function are shown to be adequate for simulating, at frame rates of 86 Hz on a 1.5 GHz desktop workstation, realistic-looking spectrograms at representative locations within a stenosed carotid bifurcation model. Via qualitative comparisons with matched in vitro data, these simulated spectrograms are shown to mimic the distinctive spectral envelopes, broadening and power characteristics associated with common carotid, stenotic jet and poststenotic recirculating flows. We conclude that the complex interaction between Doppler ultrasound and complicated clinically relevant blood flow dynamics can be simulated in real time via this relatively straightforward semiempirical approach.

  5. Spectral clustering algorithms for ultrasound image segmentation.

    PubMed

    Archip, Neculai; Rohling, Robert; Cooperberg, Peter; Tahmasebpour, Hamid; Warfield, Simon K

    2005-01-01

    Image segmentation algorithms derived from spectral clustering analysis rely on the eigenvectors of the Laplacian of a weighted graph obtained from the image. The NCut criterion was previously used for image segmentation in supervised manner. We derive a new strategy for unsupervised image segmentation. This article describes an initial investigation to determine the suitability of such segmentation techniques for ultrasound images. The extension of the NCut technique to the unsupervised clustering is first described. The novel segmentation algorithm is then performed on simulated ultrasound images. Tests are also performed on abdominal and fetal images with the segmentation results compared to manual segmentation. Comparisons with the classical NCut algorithm are also presented. Finally, segmentation results on other types of medical images are shown.

  6. TU-A-9A-02: Analysis of Variations in Clinical Doppler Ultrasound Peak Velocity Measurements

    SciTech Connect

    Zhang, Y; Stekel, S; Tradup, D; Hangiandreou, N

    2014-06-15

    Purpose: Doppler ultrasound (US) peak velocity (Vmax) measurements show considerable variations due to intrinsic spectral broadening with different scanning techniques, machines and manufacturers. We developed a semi-automated Vmax estimation method and used this method to investigate the performance of a US system for clinical Doppler Vmax measurement. Methods: Semi-automated Vmax is defined as the velocity at which the computed mean spectral profile falls to within 1 background standard deviation of the background mean. GE LOGIQ E9 system with 9L and ML6-15 probes were studied with steady flow (5.3 – 12.5 ml/s) in a Gammex OPTIMIZER 1425A phantom. All Doppler spectra were acquired by 1 operator at the distal end of 5 mm angular tube using a modified clinical carotid artery protocol. Repeatability and variation of Vmax to scanning parameters and probes were analyzed and reported as percentage, i.e. (max-min)/mean. Results: Vmax estimation had good repeatability (3.1% over 6 days for 9L, and 3.6% for ML6-15). For 9L probe, varying gain, compression, scale, SV depth and length, and frequency had minimal impact on Vmax (all variations less than 4.0%). Beam steering had slightly higher influence (largest variations across flow rates were 4.9% for 9L and 6.9% for ML6-15). For both probes, Doppler angle had the greatest effect on Vmax. Percentage increase of Vmax was largely independent of actual flow rates. For Doppler angle varied from 30 to 60°, Vmax increased 24% for 9L, and 20% for ML6-15. Vmax measured by ML6-15 were lower than that by 9L at each Doppler angle with differences less than 5%. Conclusion: The proposed Vmax estimation method is shown to be a useful tool to evaluate clinical Doppler US system performance. For the tested system and probes, Doppler angle had largest impact in measured Vmax.

  7. Color Doppler ultrasound of the hand: observations on clinical utility in rheumatoid arthritis.

    PubMed

    Saadeh, Constantine; Gaylor, Patrick; Lee, Doohi; Malacara, Jan; Gaylor, Michael

    2004-02-01

    The use of ultrasound with color Doppler in the evaluation of rheumatoid arthritis was followed in 25 patients with joint complaints. Small joint ultrasound of the metacarpophalangeal joints (MCPs) as well as the wrists was performed with supplementation by color Doppler. In addition, 6 patients were followed for at least 3 months after start of treatment of rheumatoid arthritis using the same technique. In patients with what appeared to be definite rheumatoid arthritis, ultrasound supported this diagnosis as evidenced by the finding of cortical defects, extensor tendon sheath thickening, and synovial proliferation. Increased activity by color Doppler ultrasonography was the most common finding. Significant decrease in color Doppler activity was noted in the 6 patients who were followed up after 3 months of therapy with disease-modifying agents. Therefore, the use of ultrasound with color Doppler could aid in the diagnosis and follow up of patients with rheumatoid arthritis.

  8. Doppler broadening induced spectral shift effects on reactor safety

    SciTech Connect

    Alapour, A.

    1980-01-01

    It is commonly accepted that the resonance reaction rate of any material increases when the temperature is raised. However, in a nuclear reactor the increase in resonance reaction rates with temperature at relatively high energy shifts the neutron spectrum in such a way that a net decrease in the neutron flux results at lower energies. This finding suggested that the spectral shift could significantly affect the Doppler reactivity change, warranting further investigations. The objective was to study the physical characteristics of this new phenomenon and its effects on reactor safety. The desirability of studying this effect was strengthened by the presence of discrepancies between the calculated and measured integral experiments. An exact Doppler broadening kernel, based on the Maxwellian distribution of nuclear velocities, and an accurate integral transport method NDCRAB, capable of including resonance overlap of all materials present in the reactor cell, were used in this study. The ZPR-6 Assembly 7 benchmark, a typical LMFBR reactor, was used to quantify the Doppler reactivity change for an increase in fuel temperature and to analyze the natural UO/sub 3/ sample Doppler worth in this assembly. The quantification of the various components of the Doppler reactivity change shows that the fissile material, /sup 239/Pu, has a large negative Doppler effect and contributes a large fraction to the total negative effect. The calculated Doppler effect of the natural UO/sub 3/ sample in this assembly was in good agreement with the measured value. The calculated and measured values for an increase in sample temperature from 293-0K to 1100/sup 0/K wre -0.887 Ih/kgU and -0.868 Ih/kgU.

  9. Doppler ultrasound study and venous mapping in chronic venous insufficiency.

    PubMed

    García Carriazo, M; Gómez de las Heras, C; Mármol Vázquez, P; Ramos Solís, M F

    2016-01-01

    Chronic venous insufficiency of the lower limbs is very prevalent. In recent decades, Doppler ultrasound has become the method of choice to study this condition, and it is considered essential when surgery is indicated. This article aims to establish a method for the examination, including venous mapping and preoperative marking. To this end, we review the venous anatomy of the lower limbs and the pathophysiology of chronic venous insufficiency and explain the basic hemodynamic concepts and the terminology required to elaborate a radiological report that will enable appropriate treatment planning and communication with other specialists. We briefly explain the CHIVA (the acronym for the French term "cure conservatrice et hémodynamique de l'insuffisance veineuse en ambulatoire"=conservative hemodynamic treatment for chronic venous insufficiency) strategy, a minimally invasive surgical strategy that aims to restore correct venous hemodynamics without resecting the saphenous vein.

  10. The role of Doppler ultrasound in rheumatic diseases.

    PubMed

    Porta, Francesco; Radunovic, Goran; Vlad, Violeta; Micu, Mihaela C; Nestorova, Rodina; Petranova, Tzvetanka; Iagnocco, Annamaria

    2012-06-01

    The use of Doppler techniques, including power, colour and spectral Doppler, has greatly increased in rheumatology in recent years. This is due to the ability of Doppler US (DUS) to detect pathological vascularization within joints and periarticular soft tissues, thereby demonstrating the presence of active inflammation, which has been reported to be correlated with the local neo-angiogenesis. In synovitis, DUS showed a high correlation with histological and MRI findings, thus it is considered a valid tool to detect pathological synovial vascularization. Moreover, it is more sensitive than clinical examination in detecting active joint inflammation and in the evaluation of response to treatment. In addition, DUS may be considered as a reference imaging modality in the assessment of enthesitis, MRI being not sensitive and histology not feasible. Moreover, it has been demonstrated to be able to detect changes in asymptomatic enthesis. In conclusion, DUS is a useful and sensitive tool in the evaluation and monitoring of active inflammation. Its widespread use in clinical rheumatological practice is recommended. The aim of this article is to review the current literature about the role of DUS in rheumatic diseases, analysing its validity, reliability and feasibility.

  11. Role of Ultrasound with Color Doppler in Acute Scrotum Management

    PubMed Central

    Agrawal, Alka M.; Tripathi, Prem Siddharth; Shankhwar, Amit; Naveen, C.

    2014-01-01

    Background and Objective: An acute scrotum is defined as acute pain with or without scrotal swelling, may be accompanied by local signs or general symptoms. Acute scrotal pain is a medical emergency. Depending on cause, the management is entirely different. Torsion of testis and strangulated hernia are surgical emergency; whereas, epididymo-orchitis is treated by medicines. Testicular trauma and obstructed hernia can be differentiated by taking history from patient. Physical examination adds only a little information. Color Doppler ultrasound (US) is the modality of choice to differentiate testicular torsion from inflammatory conditions and can thus help in avoiding unnecessary surgical explorations. Subjects and Methods: A study on 50 patients was conducted who were referred with history of acute scrotal pain to our department between January 2013 and January 2014. Trauma and scrotal mass were excluded from the study. The clinical presentation, outcome, and US results were analyzed. Results: Color Doppler sonography yielded a positive and negative predictive value (PPV and NPV) of 100% each for torsion, whereas, 93.9 and 70.6% for epididymo-orchitis, respectively; a sensitivity and specificity of 100% for torsion, whereas, for epididymo-orchitis it was found to be 86.1 and 85.7%, respectively. In cases of incomplete or early torsion, some residual perfusion may be detected leading to false-negative results. Conclusion: We therefore conclude that color Doppler sonography can reliably rule out testicular torsion and can thus help in avoiding unnecessary surgical explorations. Hence, it can significantly improve outcome and decrease morbidity of patient. It is an accurate, rapid, nonexpensive, nonionizing, important adjunct to clinical assessment of scrotum. PMID:25657954

  12. [Doppler ultrasound diagnosis in post-term pregnancy].

    PubMed

    Jörn, H; Funk, A; Fendel, H

    1993-09-01

    The capability of Doppler flow velocimetry to predict intrauterine growth retardation is well known. The increased morbidity and mortality rate of postterm newborns is also well known. The aim of our study was to examine if Doppler flow velocimetry is able to indicate foetal jeopardy in the postterm period. Flow velocimetry of the foetal descending aorta, the umbilical artery, the uterine arteries and in 59 cases also the foetal middle cerebral artery was obtained from 167 pregnancies after 40 completed weeks of gestation. We found significant changes of normal values in prolonged pregnancy compared to third trimester normal values, examining the mean velocity of the foetal descending aorta and the S/D-ratio of the umbilical artery. No clinically significant changes were found examining the S/D-ratio of the uterine arteries and the pulsatility index of the foetal middle cerebral artery. Daily examinations of the foetal descending aorta were carried out in 23 and of the umbilical artery in 19 cases during the last four days before delivery, and in 11 cases of the foetal middle cerebral artery during the last three days before delivery. We did not find significant changes in the medians of the mean velocity of the foetal aorta, of the S/D-ratio of the umbilical artery and of the pulsatility index of the foetal middle cerebral artery. Measurement of sensitivity and positive predictive value of the four arteries examined showed, that Doppler ultrasound could not predict small for date infants or Caesarean section because of foetal distress.(ABSTRACT TRUNCATED AT 250 WORDS)

  13. Model-based spectral estimation of Doppler signals using parallel genetic algorithms.

    PubMed

    Solano González, J; Rodríguez Vázquez, K; García Nocetti, D F

    2000-05-01

    Conventional spectral analysis methods use a fast Fourier transform (FFT) on consecutive or overlapping windowed data segments. For Doppler ultrasound signals, this approach suffers from an inadequate frequency resolution due to the time segment duration and the non-stationarity characteristics of the signals. Parametric or model-based estimators can give significant improvements in the time-frequency resolution at the expense of a higher computational complexity. This work describes an approach which implements in real-time a parametric spectral estimator method using genetic algorithms (GAs) in order to find the optimum set of parameters for the adaptive filter that minimises the error function. The aim is to reduce the computational complexity of the conventional algorithm by using the simplicity associated to GAs and exploiting its parallel characteristics. This will allow the implementation of higher order filters, increasing the spectrum resolution, and opening a greater scope for using more complex methods.

  14. The effect of dead elements on the accuracy of Doppler ultrasound measurements.

    PubMed

    Vachutka, Jaromir; Dolezal, Ladislav; Kollmann, Christian; Klein, Jakob

    2014-01-01

    The objective of this study is to investigate the effect of multiple dead elements in an ultrasound probe on the accuracy of Doppler ultrasound measurements. For this work, we used a specially designed ultrasound imaging system, the Ultrasonix Sonix RP, that provides the user with the ability to disable selected elements in the probe. Using fully functional convex, linear, and phased array probes, we established a performance baseline by measuring the parameters of a laminar parabolic flow profile. These same parameters were then measured using probes with 1 to 10 disabled elements. The acquired velocity spectra from the functional probes and the probes with disabled elements were then analyzed to determine the overall Doppler power, maximum flow velocity, and average flow velocity. Color Flow Doppler images were also evaluated in a similar manner. The analysis of the Doppler spectra indicates that the overall Doppler power as well as the detected maximum and average velocities decrease with the increasing number of disabled elements. With multiple disabled elements, decreases in the detected maximum and average velocities greater than 20% were recorded. Similar results were also observed with Color Flow Doppler measurements. Our results confirmed that the degradation of the ultrasound probe through the loss of viable elements will negatively affect the quality of the Doppler-derived diagnostic information. We conclude that the results of Doppler measurements cannot be considered accurate or reliable if there are four or more contiguous dead elements in any given probe.

  15. Direct Measurement of Basilar Membrane Motion Using Pulsed-Wave Doppler High-Frequency Ultrasound

    NASA Astrophysics Data System (ADS)

    Torbatian, Z.; Garland, P.; Adamson, R. B. A.; Bance, M.; Brown, J. A.

    2011-11-01

    We present a preliminary report on the use of a new technique for measuring the motion of the basilar membrane, high-frequency ultrasound Doppler vibrometry. Using a custom-built, 1 mm diameter probe, we collected ultrasonic reflections from intracochlear structures and applied pulsed-wave Doppler vibrometry to measure the basilar membrane response to pressure applied in the ear canal.

  16. Breast tumor angiogenesis analysis using 3D power Doppler ultrasound

    NASA Astrophysics Data System (ADS)

    Chang, Ruey-Feng; Huang, Sheng-Fang; Lee, Yu-Hau; Chen, Dar-Ren; Moon, Woo Kyung

    2006-03-01

    Angiogenesis is the process that correlates to tumor growth, invasion, and metastasis. Breast cancer angiogenesis has been the most extensively studied and now serves as a paradigm for understanding the biology of angiogenesis and its effects on tumor outcome and patient prognosis. Most studies on characterization of angiogenesis focus on pixel/voxel counts more than morphological analysis. Nevertheless, in cancer, the blood flow is greatly affected by the morphological changes, such as the number of vessels, branching pattern, length, and diameter. This paper presents a computer-aided diagnostic (CAD) system that can quantify vascular morphology using 3-D power Doppler ultrasound (US) on breast tumors. We propose a scheme to extract the morphological information from angiography and to relate them to tumor diagnosis outcome. At first, a 3-D thinning algorithm helps narrow down the vessels into their skeletons. The measurements of vascular morphology significantly rely on the traversing of the vascular trees produced from skeletons. Our study of 3-D assessment of vascular morphological features regards vessel count, length, bifurcation, and diameter of vessels. Investigations into 221 solid breast tumors including 110 benign and 111 malignant cases, the p values using the Student's t-test for all features are less than 0.05 indicating that the proposed features are deemed statistically significant. Our scheme focuses on the vascular architecture without involving the technique of tumor segmentation. The results show that the proposed method is feasible, and have a good agreement with the diagnosis of the pathologists.

  17. Design and Implementation of High Frequency Ultrasound Pulsed-Wave Doppler Using FPGA

    PubMed Central

    Hu, Chang-hong; Zhou, Qifa; Shung, K. Kirk

    2009-01-01

    The development of a field-programmable gate array (FPGA)-based pulsed-wave Doppler processing approach in pure digital domain is reported in this paper. After the ultrasound signals are digitized, directional Doppler frequency shifts are obtained with a digital-down converter followed by a low-pass filter. A Doppler spectrum is then calculated using the complex fast Fourier transform core inside the FPGA. In this approach, a pulsed-wave Doppler implementation core with reconfigurable and real-time processing capability is achieved. PMID:18986909

  18. Spectral analyses of the dual polarization Doppler weather radar data

    NASA Astrophysics Data System (ADS)

    Bachmann, Svetlana Monakhova

    2007-12-01

    Echoes in clear air from biological scatterers mixed within the resolution volumes over a large region are presented. These echoes were observed with the polarimetric prototype of the forthcoming WSR-88D weather radar. The study case occurred in the evening of September 7, 2004, at the beginning of the bird migrating season. Novel polarimetric spectral analyses are used for distinguishing signatures of birds and insects in multimodal spectra. These biological scatterers were present at the same time in the radar resolution volumes over a large area. Spectral techniques for (1) data censoring, (2) wind retrieval and (3) estimation of intrinsic values/functions of polarimetric variables for different types of scatterers are presented. The technique for data censoring in the frequency domain allows detection of weak signals. Censoring is performed on the level of spectral densities, allowing exposure of contributions to the spectrum from multiple types of scatterers. The spectral techniques for wind retrieval allow simultaneous estimation of wind from the data that are severely contaminated by migrating birds, and assessment of bird migration parameters. The intrinsic polarimetric signatures associated with the variety of scatterers can be evaluated using presented methodology. Algorithms for echo classification can be built on these. The possibilities of spectral processing using parametric estimation techniques are explored for resolving contributions to the Doppler spectrum from the three types of scatterers: passive wind tracers, actively flying insects and birds. A combination of parametric and non-parametric polarimetric spectral analyses is used to estimate the small bias introduced to the wind velocity by actively flying insects.

  19. Duplex ultrasound

    MedlinePlus

    Vascular ultrasound; Peripheral vascular ultrasound ... A duplex ultrasound combines: Traditional ultrasound: This uses sound waves that bounce off blood vessels to create pictures. Doppler ultrasound: This ...

  20. Transthoracic needle biopsy of thoracic tumours by a colour Doppler ultrasound puncture guiding device.

    PubMed Central

    Wang, H. C.; Yu, C. J.; Chang, D. B.; Yuan, A.; Lee, Y. C.; Yang, P. C.; Kuo, S. H.; Luh, K. T.

    1995-01-01

    BACKGROUND--Ultrasound guided transthoracic needle aspiration biopsy has recently been used to obtain specimens for histological diagnosis of pulmonary and mediastinal tumours. Conventional real time, grey scale puncture guiding devices cannot differentiate vascular structures, and clear visualisation of the needle shaft or tip within a desired target is not always possible. This study describes a new built-in colour Doppler ultrasound puncture guiding device and assesses the relative safety of transthoracic needle aspiration biopsy of thoracic tumours by grey scale or colour Doppler ultrasound guidance. METHODS--Thirty patients with radiographic evidence of pulmonary (22 patients) or mediastinal tumours (eight patients) underwent ultrasonographic evaluation and transthoracic needle aspiration biopsy by using the colour Doppler ultrasound puncture guiding device (Aloka UST 5045P-3.5). These tumours were initially examined by grey scale ultrasound, and colour Doppler imaging was then used to evaluate the number of blood vessels surrounding and within the target tumour and the possibility of visualisation of the needle shaft or needle tip during the aspiration biopsy procedure. RESULTS--The colour Doppler ultrasound guiding device was far superior to the grey scale device for identification of the number of vessels surrounding or within the target tumour (83% v 20%) and for visualisation of the needle shaft or needle tip (80% v 17%). CONCLUSIONS--By using the colour Doppler ultrasound puncture device, vascular structures surrounding or within the target tumour can be verified. Visualisation of the needle shaft or tip is also better. Biopsy routes can be selected to avoid puncturing vessels. This approach should be particularly helpful for guiding biopsies of mediastinal tumours, where puncturing the heart or great vessels is a potential complication. Images PMID:8553297

  1. Using rotation for steerable needle detection in 3D color-Doppler ultrasound images.

    PubMed

    Mignon, Paul; Poignet, Philippe; Troccaz, Jocelyne

    2015-08-01

    This paper demonstrates a new way to detect needles in 3D color-Doppler volumes of biological tissues. It uses rotation to generate vibrations of a needle using an existing robotic brachytherapy system. The results of our detection for color-Doppler and B-Mode ultrasound are compared to a needle location reference given by robot odometry and robot ultrasound calibration. Average errors between detection and reference are 5.8 mm on needle tip for B-Mode images and 2.17 mm for color-Doppler images. These results show that color-Doppler imaging leads to more robust needle detection in noisy environment with poor needle visibility or when needle interacts with other objects.

  2. Sensitivity evaluation of DSA-based parametric imaging using Doppler ultrasound in neurovascular phantoms

    NASA Astrophysics Data System (ADS)

    Balasubramoniam, A.; Bednarek, D. R.; Rudin, S.; Ionita, C. N.

    2016-03-01

    An evaluation of the relation between parametric imaging results obtained from Digital Subtraction Angiography (DSA) images and blood-flow velocity measured using Doppler ultrasound in patient-specific neurovascular phantoms is provided. A silicone neurovascular phantom containing internal carotid artery, middle cerebral artery and anterior communicating artery was embedded in a tissue equivalent gel. The gel prevented movement of the vessels when blood mimicking fluid was pumped through it to obtain Colour Doppler images. The phantom was connected to a peristaltic pump, simulating physiological flow conditions. To obtain the parametric images, water was pumped through the phantom at various flow rates (100, 120 and 160 ml/min) and 10 ml contrast boluses were injected. DSA images were obtained at 10 frames/sec from the Toshiba C-arm and DSA image sequences were input into LabVIEW software to get parametric maps from time-density curves. The parametric maps were compared with velocities determined by Doppler ultrasound at the internal carotid artery. The velocities measured by the Doppler ultrasound were 38, 48 and 65 cm/s for flow rates of 100, 120 and 160 ml/min, respectively. For the 20% increase in flow rate, the percentage change of blood velocity measured by Doppler ultrasound was 26.3%. Correspondingly, there was a 20% decrease of Bolus Arrival Time (BAT) and 14.3% decrease of Mean Transit Time (MTT), showing strong inverse correlation with Doppler measured velocity. The parametric imaging parameters are quite sensitive to velocity changes and are well correlated to the velocities measured by Doppler ultrasound.

  3. A new fringeline-tracking approach for color Doppler ultrasound imaging phase unwrapping

    NASA Astrophysics Data System (ADS)

    Saad, Ashraf A.; Shapiro, Linda G.

    2008-03-01

    Color Doppler ultrasound imaging is a powerful non-invasive diagnostic tool for many clinical applications that involve examining the anatomy and hemodynamics of human blood vessels. These clinical applications include cardio-vascular diseases, obstetrics, and abdominal diseases. Since its commercial introduction in the early eighties, color Doppler ultrasound imaging has been used mainly as a qualitative tool with very little attempts to quantify its images. Many imaging artifacts hinder the quantification of the color Doppler images, the most important of which is the aliasing artifact that distorts the blood flow velocities measured by the color Doppler technique. In this work we will address the color Doppler aliasing problem and present a recovery methodology for the true flow velocities from the aliased ones. The problem is formulated as a 2D phase-unwrapping problem, which is a well-defined problem with solid theoretical foundations for other imaging domains, including synthetic aperture radar and magnetic resonance imaging. This paper documents the need for a phase unwrapping algorithm for use in color Doppler ultrasound image analysis. It describes a new phase-unwrapping algorithm that relies on the recently developed cutline detection approaches. The algorithm is novel in its use of heuristic information provided by the ultrasound imaging modality to guide the phase unwrapping process. Experiments have been performed on both in-vitro flow-phantom data and in-vivo human blood flow data. Both data types were acquired under a controlled acquisition protocol developed to minimize the distortion of the color Doppler data and hence to simplify the phase-unwrapping task. In addition to the qualitative assessment of the results, a quantitative assessment approach was developed to measure the success of the results. The results of our new algorithm have been compared on ultrasound data to those from other well-known algorithms, and it outperforms all of them.

  4. Common carotid artery pseudoaneurysm after neck dissection: colour Doppler ultrasound and multidetector computed tomography findings.

    PubMed

    Flor, N; Sardanelli, F; Ghilardi, G; Tentori, A; Franceschelli, G; Felisati, G; Cornalba, G P

    2007-05-01

    Common carotid artery pseudoaneurysm is a rare disease, which has been previously unreported in association with neck dissection. We describe the Doppler ultrasound and multidetector computed tomography (CT) findings of a case of carotid pseudoaneurysm, one month after pharyngolaryngectomy with bilateral neck dissection. Multidetector CT confirmed the diagnosis made on the basis of Doppler ultrasound; the high image quality of axial and three-dimensional reconstructions avoided the need for pre-operative conventional angiography. In the presence of a pulsatile cervical mass after neck surgery, pseudoaneurysm of the carotid artery should be included in the differential diagnosis, and multidetector CT can be the sole pre-operative diagnostic imaging modality.

  5. The effect of foot position on Power Doppler Ultrasound grading of Achilles enthesitis.

    PubMed

    Zappia, Marcello; Cuomo, Giovanna; Martino, Maria Teresa; Reginelli, Alfonso; Brunese, Luca

    2016-06-01

    The aim of this study was to determine whether foot position could modify power Doppler grading in evaluation of the Achilles enthesis. Eighteen patients with clinical Achilles enthesitis were studied with power Doppler ultrasound (PDUS) in five different positions of the foot: active and passive dorsiflexion, neutral position, active and passive plantar flexion. The Doppler signal was graded in any position and compared with the others. The Doppler signal was higher with the foot in plantar flexion and decreased gradually, sometimes till to disappear, while increasing dorsiflexion. The Doppler signal was always less during the active keeping of the position of the joint, than during the passive. The PDUS examination of the Achilles enthesis should be performed also with the foot in passive plantar flexion, in order not to underestimate the degree of vascularization.

  6. Time-resolved volumetric MRI blood flow: a Doppler ultrasound perspective

    NASA Astrophysics Data System (ADS)

    van Pelt, Roy; Oliván Bescós, Javier; Nagel, Eike; Vilanova, Anna

    2014-03-01

    Hemodynamic information is increasingly inspected to assess cardiovascular disease. Abnormal blood-flow patterns include high-speed jet flow and regurgitant flow. Such pathological blood-flow patterns are nowadays mostly inspected by means of color Doppler ultrasound imaging. To date, Doppler ultrasound has been the prevailing modality for blood-flow analysis, providing non-invasive and cost-effective blood-flow imaging. Since recent years, magnetic resonance imaging (MRI) is increasingly employed to measure time-resolved blood-flow data. Albeit more expensive, MRI enables volumetric velocity encoding, providing true vector-valued data with less noise. Domain experts in the field of ultrasound and MRI have extensive experience in the interpretation of blood-flow information, although they employ different analysis techniques. We devise a visualization framework that extends on common Doppler ultrasound visualizations, exploiting the added value of MRI velocity data, and aiming for synergy between the domain experts. Our framework enables experts to explore the advantages and disadvantages of the current renditions of their imaging data. Furthermore, it facilitates the transition from conventional Doppler ultrasound images to present-day high-dimensional velocity fields. To this end, we present a virtual probe that enables direct exploration of MRI-acquired blood-flow velocity data using user-friendly interactions. Based on the probe, Doppler ultrasound inspired visualizations convey both in-plane and through-plane blood-flow velocities. In a compound view, these two-dimensional visualizations are linked to state-of-the-art three-dimensional blood-flow visualizations. Additionally, we introduce a novel volume rendering of the blood-flow velocity data that emphasizes anomalous blood-flow patterns. The visualization framework was evaluated by domain experts, and we present their feedback.

  7. Oxygen consumption estimation with combined color doppler ultrasound and photoacoustic microscopy: a phantom study

    NASA Astrophysics Data System (ADS)

    Jiang, Yan; Harrison, Tyler; Forbrich, Alex; Zemp, Roger J.

    2011-03-01

    The metabolic rate of oxygen consumption (MRO2) quantifies tissue metabolism, which is important for diagnosis of many diseases. For a single vessel model, the MRO2 can be estimated in terms of the mean flow velocity, vessel crosssectional area, total concentration of hemoglobin (CHB), and the difference between the oxygen saturation (sO2) of blood flowing into and out of the tissue region. In this work, we would like to show the feasibility to estimate MRO2 with our combined photoacoustic and high-frequency ultrasound imaging system. This system uses a swept-scan 25-MHz ultrasound transducer with confocal dark-field laser illumination optics. A pulse-sequencer enables ultrasonic and laser pulses to be interlaced so that photoacoustic and Doppler ultrasound images are co-registered. Since the mean flow velocity can be measured by color Doppler ultrasound, the vessel cross-sectional area can be measured by power Doppler or photoacoustic imaging, and multi-wavelength photoacoustic methods can be used to estimate sO2 and CHB, all of these parameters necessary for MRO2 estimation can be provided by our system. Experiments have been performed on flow phantoms to generate co-registered color Doppler and photoacoustic images. To verify the sO2 estimation, two ink samples (red and blue) were mixed in various concentration ratios to mimic different levels of sO2, and the result shows a good match between the calculated concentration ratios and actual values.

  8. Atypical Cerebral Lateralisation in Adults with Compensated Developmental Dyslexia Demonstrated Using Functional Transcranial Doppler Ultrasound

    ERIC Educational Resources Information Center

    Illingworth, Sarah; Bishop, Dorothy V. M.

    2009-01-01

    Functional transcranial Doppler ultrasound (fTCD) is a relatively new and non-invasive technique that assesses cerebral lateralisation through measurements of blood flow velocity in the middle cerebral arteries. In this study fTCD was used to compare functional asymmetry during a word generation task between a group of 30 dyslexic adults and a…

  9. Effect of method and parameters of spectral analysis on selected indices of simulated Doppler spectra.

    PubMed

    Kaluzynski, K; Palko, T

    1993-05-01

    The sensitivity of Doppler spectral indices (mean frequency, maximum frequency, spectral broadening index and turbulence intensity) to the conditions of spectral analysis (estimation method, data window, smoothing window or model order) increases with decreasing signal bandwidth and growing index complexity. The bias of spectral estimate has a more important effect on these indices than its variance. A too low order, in the case of autoregressive modeling and minimum variance methods, and excessive smoothing, in the case of the FFT method, result in increased errors of Doppler spectral indices. There is a trade-off between the errors resulting from a short data window and those due to insufficient temporal resolution.

  10. Doppler ultrasound in the measurement of pulse wave velocity: agreement with the Complior method

    PubMed Central

    2011-01-01

    Aortic stiffness is an independent predictor factor for cardiovascular risk. Different methods for determining pulse wave velocity (PWV) are used, among which the most common are mechanical methods such as SphygmoCor or Complior, which require specific devices and are limited by technical difficulty in obtaining measurements. Doppler guided by 2D ultrasound is a good alternative to these methods. We studied 40 patients (29 male, aged 21 to 82 years) comparing the Complior method with Doppler. Agreement of both devices was high (R = 0.91, 0.84-0.95, 95% CI). The reproducibility analysis revealed no intra-nor interobserver differences. Based on these results, we conclude that Doppler ultrasound is a reliable and reproducible alternative to other established methods for the measurement of aortic PWV. PMID:21496271

  11. Remote Electromagnetic Vibration of Steerable Needles for Imaging in Power Doppler Ultrasound

    PubMed Central

    Cabreros, Sarah S.; Jimenez, Nina M.; Greer, Joseph D.; Adebar, Troy K.; Okamura, Allison M.

    2015-01-01

    Robotic needle steering systems for minimally invasive medical procedures require complementary medical imaging systems to track the needles in real time. Ultrasound is a promising imaging modality because it offers relatively low-cost, real-time imaging of the needle. Previous methods applied vibration to the base of the needle using a voice coil actuator, in order to make the needle visible in power Doppler ultrasound. We propose a new method for needle tip vibration, using electromagnetic actuation of small permanent magnets placed inside the needle to improve needle tip visibility in power Doppler imaging. Robotic needle insertion experiments using artificial tissue and ex vivo porcine liver showed that the electromagnetic tip vibration method can generate a stronger Doppler response compared to the previous base vibration method, resulting in better imaging at greater needle depth in tissue. It also eliminates previous issues with vibration damping along the shaft of the needle. PMID:26413379

  12. Remote Electromagnetic Vibration of Steerable Needles for Imaging in Power Doppler Ultrasound.

    PubMed

    Cabreros, Sarah S; Jimenez, Nina M; Greer, Joseph D; Adebar, Troy K; Okamura, Allison M

    2015-05-01

    Robotic needle steering systems for minimally invasive medical procedures require complementary medical imaging systems to track the needles in real time. Ultrasound is a promising imaging modality because it offers relatively low-cost, real-time imaging of the needle. Previous methods applied vibration to the base of the needle using a voice coil actuator, in order to make the needle visible in power Doppler ultrasound. We propose a new method for needle tip vibration, using electromagnetic actuation of small permanent magnets placed inside the needle to improve needle tip visibility in power Doppler imaging. Robotic needle insertion experiments using artificial tissue and ex vivo porcine liver showed that the electromagnetic tip vibration method can generate a stronger Doppler response compared to the previous base vibration method, resulting in better imaging at greater needle depth in tissue. It also eliminates previous issues with vibration damping along the shaft of the needle.

  13. Scalpel versus electrosurgery: Comparison of gingival perfusion status using ultrasound Doppler flowmetry

    PubMed Central

    Manivannan, N.; Ahathya, R. S.; Rajaram, P. C.

    2013-01-01

    The main prerequisites of any surgical procedure are achievement of good visibility and access to the site with minimal bleeding and rapid and painless healing. With the advancement of technology the armamentarium for oral surgical procedures has also widened. The use of alternate methods to the traditional scalpel such as electrosurgery, laser, and chemicals has been widely experimented with. This article aims to report the gingival perfusion pre-operatively and post-operatively, comparing the use of scalpel and electrosurgery in different anatomic sites in patient. Since wound healing is influenced by its revascularization rate, which follows the pattern of new connective tissue formation, the perfusion status of the gingiva has been studied using ultrasound spectral Doppler. The results of our study show that there was 30% more blood flow by 7th day, 19% more blood flow by 15th day and 11% more blood flow by 30th day in sites where the scalpel was used compared with sites where electrosurgery technique was used. PMID:23956596

  14. Doppler Ultrasound Detection of Preclinical Changes in Foot Arteries in Early Stage of Type 2 Diabetes

    PubMed Central

    Leoniuk, Jolanta; Łukasiewicz, Adam; Szorc, Małgorzata; Sackiewicz, Izabela; Janica, Jacek; Łebkowska, Urszula

    2014-01-01

    Summary Background There are few reports regarding the changes within the vessels in the initial stage of type 2 diabetes. The aim of this study was to estimate the hemodynamic and morphological parameters in foot arteries in type 2 diabetes subjects and to compare these parameters to those obtained in a control group of healthy volunteers. Material/Methods Ultrasound B-mode, color Doppler and pulse wave Doppler imaging of foot arteries was conducted in 37 diabetic patients and 36 non-diabetic subjects to determine their morphological (total vascular diameter and flow lumen diameter) and functional parameters (spectral analysis). Results In diabetic patients, the overall vascular diameter and wall thickness were statistically significantly larger when compared to the control group in the right dorsalis pedis artery (P=0.01; P=0.001), left dorsalis pedis artery (P=0.007; P=0.006), right posterior tibial artery (P=0.005; P=0.0005), and left posterior tibial artery (P=0.007; P=0.0002). No significant differences were observed in both groups in flow lumen diameters and blood flow parameters (PSV, EDV, PI, RI). In the diabetic group, the level of HbA1c positively correlated with flow resistance index in the right dorsalis pedis artery (r=0.38; P=0.02), right posterior tibial artery (r=0.38; P=0.02) and left posterior tibial artery (r=0.42; P=0.009). The pulsatility index within the dorsalis pedis artery decreased with increased trophic skin changes (r=–0.431, P=0.009). Conclusions In the diabetic group, overall artery diameters larger than and flow lumina comparable to the control group suggest vessel wall thickening occurring in the early stage of diabetes. Doppler flow parameters are comparable in both groups. In the diabetic group, the level of HbA1c positively correlated with flow resistance index and negative correlation was observed between the intensity of trophic skin changes and the pulsatility index. PMID:25202434

  15. The role of tissue harmonic imaging ultrasound combined with power Doppler ultrasound in the diagnosis of childhood febrile urinary tract infections

    PubMed Central

    İlarslan, Nisa Eda Çullas; Fitöz, Ömer Suat; Öztuna, Derya Gökmen; Küçük, Nuriye Özlem; Yalçınkaya, Fatma Fatoş

    2015-01-01

    Aim: This study assessed the ability of tissue harmonic imaging ultrasound combined with power Doppler ultrasound in the detection of childhood febrile urinary tract infections in comparison with the gold standard reference method: Tc-99m dimercaptosuccinicacid renal cortical scintigraphy. Material and Methods: This prospective study included 60 patients who were hospitalized with a first episode of febrile urinary tract infections. All children were examined with dimercaptosuccinicacid scan and tissue harmonic imaging ultrasound combined with power Doppler ultrasound within the first 3 days of admission. Results: Signs indicative of acute infection were observed in 29 patients according to the results of tissue harmonic imaging ultrasound combined with power Doppler ultrasound while dimercaptosuccinicacid scan revealed abnormal findings in 33 patients. The sensitivity, specificity, positive predictive value and negative predictive value of tissue harmonic imaging combined with power Doppler ultrasound using dimercaptosuccinicacid scintigraphy as the reference method in patients diagnosed with first episode febrile urinary tract infections were calculated as 57.58% (95% confidence interval: 40.81%–72.76%); 62.96% (95% confidence interval: 44.23%–78.47%); 65.52% (95% confidence interval: 52.04%–77%); 54.84% (95% confidence interval: 41.54%–67.52%); respectively. Conclusions: Although current results exhibit inadequate success of power Doppler ultrasound, this practical and radiation-free method may soon be comprise a part of the routine ultrasonographic evaluation of febrile urinary tract infections of childhood if patients are evaluated early and under appropriate sedation. PMID:26265892

  16. Use of power Doppler ultrasound-guided biopsies to locate regions of tumour hypoxia.

    PubMed Central

    Evans, S. M.; Laughlin, K. M.; Pugh, C. R.; Sehgal, C. M.; Saunders, H. M.

    1997-01-01

    The purpose of this study was to determine whether power Doppler ultrasound techniques could be used to direct biopsies into tumour regions with relatively low red blood cell flux, and therefore preferentially sample regions that were relatively hypoxic. Subcutaneous 9L glioma rat tumours were biopsied using power Doppler ultrasound guidance. Immunohistochemical detection of the 2-nitroimidazole EF5 was performed to determine the presence and level of hypoxia in the biopsy samples. Comparisons between the power Doppler-determined red blood cell flux and EF5 binding were made. In seven out of eight tumours studied, power Doppler ultrasound allowed differentiation of a relatively hypoxic region from a relatively oxic region by localizing relatively low vs high red blood cell flux areas respectively. In one of these seven tumours, RBC flux was high in both biopsied sites and hypoxia was not present in either. In two of these seven tumours, hypoxia was present in each biopsy and both of the red blood cell flux measurements were low. In the eighth tumour, both the EF5 binding and the red blood cell flux measurements were low. In this tumour, low EF5 binding was due to the dominance of necrotic cells, which will not reduce or bind EF5 in the biopsy specimen. Using EF5-binding techniques, we have confirmed that regions of relatively low red blood cell flux are more hypoxic than those with relatively high red blood cell flux. Counterstaining specimens with haematoxylin and eosin allows differentiation of low EF5-binding regions due to oxia vs necrosis. These methods have clinical implications for the expanded use of power Doppler ultrasound as a means to direct tissue sampling when it is important to identify the presence of hypoxia. Images Figure 1 Figure 2 Figure 4 Figure 5 PMID:9374376

  17. Cerebral blood flow in the newborn infant: comparison of Doppler ultrasound and /sup 133/xenon clearance

    SciTech Connect

    Greisen, G.; Johansen, K.; Ellison, P.H.; Fredriksen, P.S.; Mali, J.; Friis-Hansen, B.

    1984-03-01

    Two techniques of Doppler ultrasound examination, continuous-wave and range-gated, applied to the anterior cerebral artery and to the internal carotid artery, were compared with /sup 133/xenon clearance after intravenous injection. Thirty-two sets of measurements were obtained in 16 newborn infants. The pulsatility index, the mean flow velocity, and the end-diastolic flow velocity were read from the Doppler recordings. Mean cerebral blood flow was estimated from the /sup 133/Xe clearance curves. The correlation coefficients between the Doppler and the /sup 133/Xe measurements ranged from 0.41 to 0.82. In the subset of 16 first measurements in each infant, there were no statistically significant differences between the correlation coefficients of the various Doppler ultrasound variables, but the correlation coefficients were consistently lower for the pulsatility index than for mean flow velocity or end-diastolic flow velocity, and they were consistently higher for the range-gated than for the continuous-wave Doppler technique.

  18. High frequency ultrasound with color Doppler in dermatology*

    PubMed Central

    Barcaui, Elisa de Oliveira; Carvalho, Antonio Carlos Pires; Lopes, Flavia Paiva Proença Lobo; Piñeiro-Maceira, Juan; Barcaui, Carlos Baptista

    2016-01-01

    Ultrasonography is a method of imaging that classically is used in dermatology to study changes in the hypoderma, as nodules and infectious and inflammatory processes. The introduction of high frequency and resolution equipments enabled the observation of superficial structures, allowing differentiation between skin layers and providing details for the analysis of the skin and its appendages. This paper aims to review the basic principles of high frequency ultrasound and its applications in different areas of dermatology. PMID:27438191

  19. Duplex Doppler ultrasound study of the temporomandibular joint.

    PubMed

    Stagnitti, A; Marini, A; Impara, L; Drudi, F M; Lo Mele, L; Lillo Odoardi, G

    2012-06-01

    Sommario INTRODUZIONE: La fisiologia articolare dell’articolazione temporo-mandibolare (ATM) può essere esaminata sia dal punto di vista clinico che strumentale. La diagnostica per immagini ha da tempo contribuito con la risonanza magnetica (RM) e anche con la radiografia (Rx) e la tomografia computerizzata (TC) all’analisi della morfologia dei capi articolari e della cinetica condilare. L’esame duplex-ecodoppler è una metodica di largo impiego nello studio delle strutture in movimento in particolar modo a livello delle strutture del sistema vascolare. MATERIALI E METODI: È stata utilizzata un’apparecchiatura Toshiba APLIO SSA-770A, con l’uso di tecnica duplex-ecodoppler multi display, che consente la visualizzazione contemporanea dell’immagine ecografica e dei segnali Doppler utilizzando una sonda lineare del tipo phased array con cristalli trasduttori funzionanti ad una frequenza fondamentale di 6 MHz per gli spettri Doppler pulsati e 7.5 MHz per l’imaging ecografico. Sono stati esaminati nel Dipartimento di Scienze Radiologiche, Oncologiche e Anatomo-patologiche dell’Università “Sapienza” di Roma, 30 pazienti del reparto di Ortognatodonzia dell’Istituto di Odontoiatria della stessa Università. RISULTATI: Nei pazienti normali si è ottenuta un’alternanza regolare degli spettri Doppler, mentre nei soggetti con disfunzioni del complesso condilo-meniscale, si è persa la regolarità della sommatoria degli spettri di Fourier, con altezze incostanti in relazione a spostamenti irregolari del complesso condilo-meniscale. CONCLUSIONI: L’esame ecodoppler si è dimostrato, in tutti i pazienti, capace di discriminare quelli normali dai patologici e tra questi ultimi ha permesso di identificare gli aspetti più significativi delle patologie disfunzionali.

  20. Doppler ultrasound study of penis in men with systemic sclerosis: a correlation with Doppler indices of renal and digital arteries.

    PubMed

    Rosato, E; Barbano, B; Gigante, A; Cianci, R; Molinaro, I; Quarta, S; Digiulio, M A; Messineo, D; Pisarri, S; Salsano, F

    2013-01-01

    Erectile dysfunction (ED) prevalence in male systemic sclerosis (SSc) is high and its pathogenesis is unclear. The aim of the study is to assess correlation between Doppler ultrasound indices of penis and kidneys or digital arteries in male systemic sclerosis. Fourteen men with systemic sclerosis were enrolled in this study. Erectile function was investigated by the International Index of Erectile Function-5. Peak systolic velocity, end diastolic velocity, resistive index, pulsative index, and systolic/diastolic ratio were measured on the cavernous arteries at the peno-scrotal junction in the flaccid state, on the interlobar artery of both kidneys and all ten proper palmar digital arteries. Ten (71 percent) patients have an International Index of Erectile Function-5 less than 21. Reduction of penis peak systolic velocity was observed in all SSc subjects. Doppler indices of cavernous arteries correlate with the International Index of Erectile Function-5. The renal and digital arteries resistive index demonstrated a good correlation (p less than 0.0001) with International Index of Erectile Function-5. A positive correlation exists between penis and kidney arteries Doppler indices: end diastolic velocity (p less than 0.05, r=0.54), resistive index (p less than 0.0001, r=0.90), systolic/diastolic ratio (p less than 0.01, r=0.69). A positive correlation was observed between penis and digital arteries Doppler indices: peak systolic velocity (p less than 0.01, r=0.68), end diastolic velocity (p less than 0.01, r=0.75), resistive index (p less than 0.001, r=0.79), systolic/diastolic ratio (p less than 0.05, r=0.59). A correlation exists between arterial impairment of penis and renal or digital arteries.

  1. Doppler ultrasound wall removal based on the spatial correlation of wavelet coefficients.

    PubMed

    Jin, Dawei; Wang, Yuanyuan

    2007-11-01

    In medical Doppler ultrasound systems, a high-pass filter is commonly used to reject echoes from the vessel wall. However, this leads to the loss of the information from the low velocity blood flow. Here a spatially selective noise filtration algorithm cooperating with a threshold denoising based on wavelets coefficients is applied to estimate the wall clutter. Then the blood flow signal is extracted by subtracting the wall clutter from the mixed signal. Experiments on computer simulated signals with various clutter-to-blood power ratios indicate that this method achieves a lower mean relative error of spectrum than the high-pass filtering and other two previously published separation methods based on the recursive principle component analysis and the irregular sampling and iterative reconstruction, respectively. The method also performs well when applied to in vivo carotid signals. All results suggest that this approach can be implemented as a clutter rejection filter in Doppler ultrasound instruments.

  2. Combined B-Mode and Multigate Spectral Doppler-Mode Imaging for Flow-Mediated Dilation Investigation

    NASA Astrophysics Data System (ADS)

    Francalanci, Lorenzo; Palombo, Carlo; Ghiadoni, Lorenzo; Bini, Giacomo; Bassi, Luca; Tortoli, Piero

    Flow-mediated dilation (FMD) is an established non-invasive method to assess the endothelial function by ultrasound. Blood flow in the brachial artery is restricted by a cuff for about 5 min: during the reactive hyperemia following occlusion release, the consequent increase in wall shear stress stimulates the endothelial cells to release nitric oxide, a powerful vasodilator that causes relaxation of tunica media smooth muscle. By measuring the arterial diameter change induced by reactive hyperemia, a possible endothelial dysfunction can be detected. The traditional approach consists in the evaluation of arterial diameter changes, while the shear stress increase (i.e. the stimulus for dilation) has not been directly estimated so far. This paper describes an approach to simultaneously measure the wall shear rate (WSR), i.e. the blood velocity gradient near the walls, and the associated diameter changes. The WSR is measured through multigate spectral Doppler (MSD) analysis while B-Mode images are processed to estimate the instantaneous diameter. This approach was implemented in the ULtrasound Advanced Open Platform (ULA-OP), which can be programmed to arbitrarily interleave B- and PW Doppler- Modes. The method implementation and the results of a clinical validation over 15 healthy volunteers are reported.

  3. A real-time device for converting Doppler ultrasound audio signals into fluid flow velocity.

    PubMed

    Herr, Michael D; Hogeman, Cynthia S; Koch, Dennis W; Krishnan, Anandi; Momen, Afsana; Leuenberger, Urs A

    2010-05-01

    A Doppler signal converter has been developed to facilitate cardiovascular and exercise physiology research. This device directly converts audio signals from a clinical Doppler ultrasound imaging system into a real-time analog signal that accurately represents blood flow velocity and is easily recorded by any standard data acquisition system. This real-time flow velocity signal, when simultaneously recorded with other physiological signals of interest, permits the observation of transient flow response to experimental interventions in a manner not possible when using standard Doppler imaging devices. This converted flow velocity signal also permits a more robust and less subjective analysis of data in a fraction of the time required by previous analytic methods. This signal converter provides this capability inexpensively and requires no modification of either the imaging or data acquisition system.

  4. Embedded System for Real-Time Digital Processing of Medical Ultrasound Doppler Signals

    NASA Astrophysics Data System (ADS)

    Ricci, S.; Dallai, A.; Boni, E.; Bassi, L.; Guidi, F.; Cellai, A.; Tortoli, P.

    2008-12-01

    Ultrasound (US) Doppler systems are routinely used for the diagnosis of cardiovascular diseases. Depending on the application, either single tone bursts or more complex waveforms are periodically transmitted throughout a piezoelectric transducer towards the region of interest. Extraction of Doppler information from echoes backscattered from moving blood cells typically involves coherent demodulation and matched filtering of the received signal, followed by a suitable processing module. In this paper, we present an embedded Doppler US system which has been designed as open research platform, programmable according to a variety of strategies in both transmission and reception. By suitably sharing the processing tasks between a state-of-the-art FGPA and a DSP, the system can be used in several medical US applications. As reference examples, the detection of microemboli in cerebral circulation and the measurement of wall _distension_ in carotid arteries are finally presented.

  5. Use of an ultrasound blood-mimicking fluid for Doppler investigations of turbulence in vitro.

    PubMed

    Thorne, Meghan L; Poepping, Tamie L; Rankin, Richard N; Steinman, David A; Holdsworth, David W

    2008-07-01

    Turbulence is an important factor in the assessment of stenotic disease and a possible causative mechanism for thromboembolism. Previous Doppler studies of turbulence have typically used whole-blood preparations or suspensions of erythrocytes. Recently, a water-glycerol based blood-mimicking fluid (BMF) has been developed for use in Doppler ultrasound studies. This fluid has desirable ultrasound properties but it has not previously been described during in vitro investigations of turbulence intensity. We report on investigations of grid-generated and constrained-jet turbulence in an in vitro test system. The BMF was found to generate significant levels of turbulence during steady flow at physiological flow rates, producing turbulent patterns in the distal region that were consistent with previous studies. Turbulence intensity increased significantly with flow rate (p < 0.005) for both the constrained jet and the constrained grid. Based on our observations, we conclude that a water-glycerol based BMF provides a suitable working fluid during in vitro investigations of turbulence using Doppler ultrasound.

  6. Preoperative color Doppler ultrasound assessment of the lateral thoracic artery perforator flap and its branching pattern.

    PubMed

    Tashiro, Kensuke; Harima, Mitsunobu; Mito, Daisuke; Shibata, Takashi; Furuya, Megumi; Kato, Motoi; Yamamoto, Takumi; Yamashita, Shuji; Narushima, Mitsunaga; Iida, Takuya; Koshima, Isao

    2015-06-01

    The anatomy of the lateral thoracic artery perforator flap remains controversial, but this region is extremely useful as a reconstructive donor site. In this report, we describe the usefulness of the preoperative color Doppler ultrasound evaluation for the harvesting of the lateral thoracic artery perforator flap, and we clarify its branching pattern. Twenty-seven patients underwent the preoperative color Doppler ultrasound assessment before perforator flaps were harvested. We evaluated the branching pattern and the diameter of the flaps by direct observation. All flaps were successfully transferred, and it was found that the branching pattern of the lateral thoracic perforator is divided into three groups: the superficial branch, the medial branch, and the deep branch. Their appearance ratios were 48.1% (13/27), 14.8% (4/27), and 81.5% (22/27), respectively. The lateral thoracic artery perforator flap has a great deal of anatomical variation, and vessels with relatively small diameters compared to those of other flaps. This is why flaps from this region are not currently popular. This study revealed the superiority of the color Doppler ultrasound for preoperative planning of the lateral thoracic artery perforator flap elevation. Furthermore, the branching pattern and the diameters of the different branches were specified.

  7. Quantitative investigation of in vitro flow using three-dimensional colour Doppler ultrasound.

    PubMed

    Guo, Z; Moreau, M; Rickey, D W; Picot, P A; Fenster, A

    1995-01-01

    A quantitative in vitro flow study was performed by using a three-dimensional colour Doppler imaging system. This system was based on a clinical ultrasound instrument with its transducer mounted on a motor-driven translation stage. A vascular and tissue-mimicking phantom containing two wall-less vessels, one normal and another stenotic, was used to quantify the measurement accuracy of the flow velocity and the flow field. Steady state flows, having Reynolds numbers ranging between 460 and 1300, were generated by a computer-controlled positive displacement pump. Effects of the parameter settings of the ultrasound instrument on results of the estimation of flow field were also studied. Experimental results show that our three-dimensional colour Doppler system's velocity accuracy was better than 7% of the Nyquist velocity and its spatial accuracy was better than 0.5 mm. The system showed a good correlation (r = 0.999) between the estimated and the true mean flow velocity, and a good correlation (r = 0.998) between the estimated maximum and the true mean flow velocity. This study is our first step toward validating the measurement of the three-dimensional velocity and wall shear stress distributions by using three-dimensional colour Doppler ultrasound

  8. Activity of Crohn's disease assessed by colour Doppler ultrasound analysis of the affected loops.

    PubMed

    Esteban, J M; Maldonado, L; Sanchiz, V; Minguez, M; Benages, A

    2001-01-01

    The aim of this study was to evaluate with colour Doppler ultrasound the vascular changes in the wall of the loops affected by Crohn's disease, and to establish whether these changes reflects clinical or biochemical activity of Crohn's disease. Seventy-nine patients with Crohn's disease (44 with active disease and 35 inactive patients) were studied with frequency- and amplitude-encoded duplex Doppler sonography. A group of 35 healthy volunteers were also included. The exam consisted of the search for colour signals in the walls of the loops affected by Crohn's disease, classifying the degree of vascularity with a simple scoring system into three groups: absence of colour signal (score of 0); weak or scattered colour signals (score of 1); and multiple colour signals or clear identification of vessels in the loops walls (score of 2). Doppler curves were obtained of the detected vessels with measurement of the resistive index (RI). There was a visible increase in the gut walls' vascularity in the active patients compared with those with inactive disease. The mean RI was statistically significantly lower in the gut wall vessels of the patients with active illness than that obtained in the inactive patients. Colour Doppler ultrasound is a useful tool in the assessment of activity in Crohn's disease.

  9. Interactive realtime Doppler-ultrasound visualization of the heart.

    PubMed

    Heid, V; Evers, H; Henn, C; Glombitza, G; Meinzer, H P

    2000-01-01

    Heart valve insufficiencies can optimally be assessed using transesophageal, triggered, three-dimensional ultrasound imaging. The dynamic ultrasound data contain morphological as well as functional components which are recorded and displayed simultaneously. It allows the visualization of intracardiac motion which is an important parameter to detect abnormal flow caused by defect valves. A realtime reconstruction is desired to get a spatial impression on the one hand and to interactively clip parts of the volume on the other hand. Therefore, we use the OpenGL Volumizer API. Scalability of the visualization was tested with respect to different workstations and graphics resources using a Multipipe Utility library. The combination of both APIs enables a visualization of volumetric and functional data with frame rates up to 10 frames per second. By using the proposed method, it is possible to visualize the jet in the original color-coding which is employed during a conventional two-dimensional examination for displaying the velocity values. The morphological and the functional data are handled as two independent data channels. A good scalability from low cost up to high end graphic workstations is given by the use of the MPU. The quality of the resulting 3D images allows exact differentiation of heart valve insufficiencies to support the diagnostic procedure.

  10. Doppler ultrasound venous mapping of the lower limbs

    PubMed Central

    Galeandro, Aldo Innocente; Quistelli, Giovanni; Scicchitano, Pietro; Gesualdo, Michele; Zito, Annapaola; Caputo, Paola; Carbonara, Rosa; Galgano, Giuseppe; Ciciarello, Francesco; Mandolesi, Sandro; Franceschi, Claude; Ciccone, Marco Matteo

    2012-01-01

    Background The study aim was to test the accuracy (intra and interobserver variability), sensitivity, and specificity of a simplified noninvasive ultrasound methodology for mapping superficial and deep veins of the lower limbs. Methods 62 consecutive patients, aged 62 ± 11 years, were enrolled. All underwent US-examinations, performed by two different investigators, of both legs, four anatomical parts, and 17 veins, to assess the interobserver variability of evaluation of superficial and deep veins of the lower limbs. Results Overall the agreement between the second versus the first operator was very high in detecting reflux (sensitivity 97.9, specificity 99.7, accuracy 99.5; P = 0.80 at McNemar test). The higher CEAP classification stages were significantly associated with reflux (odds ratio: 1.778, 95% confidence interval: 1.552–2.038; P < 0.001) as well as with thrombosis (odds ratio: 2.765, 95% confidence interval: 1.741–4.389; P < 0.001). Thus, our findings show a strict association between the symptoms of venous disorders and ultrasound evaluation results for thrombosis or reflux. Conclusion This study demonstrated that our venous mapping protocol is a reliable method showing a very low interobserver variability, which makes it accurate and reproducible for the assessment of the morphofunctional status of the lower limb veins. PMID:22371652

  11. Two-dimensional blood flow vectors obtained with bidirectional Doppler ultrasound.

    PubMed

    Masuno, Genta; Nagaoka, Ryo; Omori, Aiko; Ishikawa, Yasuo; Akagawa, Osamu; Arakawa, Mototaka; Saijo, Yoshifumi

    2014-01-01

    Precise measurement of blood flow is important because blood flow closely correlates formation of thrombus and atherosclerotic plaque. Among clinically applied modalities for blood flow measurement, color Doppler ultrasound shows two-dimensional (2D) distribution of one-dimensional blood flow component along the ultrasound beam. In the present study, 2D blood flow vector is obtained with high temporal and bidirectional Doppler ultrasound technique. Linear array probe with the central frequency of 7.5 MHz and an ultrasound data acquisition system with 128 transmit and 128 receive channels were equipped. Frame rate of 5 kHz was achieved by parallel receive beam forming with a wide transmitted wave. The flow velocity was measured from two different angles by beam steering. The interval of two measurements was 0.8 msec and it was considered as almost one moment to obtain 2D blood flow vector. B-mode image and 2D blood flow vector of the pulsatile flow in a carotid artery model showed small vortex at the bifurcation area. The method was also applied for visualization of in vivo blood flow vector in human carotid arteries. 2D blood flow measurement may predict the risk area of thrombus and plaque formation induced by abnormal blood flow.

  12. Distribution of mean Doppler shift, spectral width, and skewness of coherent 50-MHz auroral radar backscatter

    SciTech Connect

    Watermann, J.; McNamara, A.G. ); Sofko, G.J.; Koehler, J.A. )

    1989-06-01

    Some 7,700 radio aurora spectra obtained from a six link 50-MHz CW radar network set up on the Canadian prairies were analyzed with respect to the distributions of mean Doppler shift, spectral width and skewness. A comparison with recently published SABRE results obtained at 153 MHz shows substantial differences in the distributions which are probably due to different experimental and geophysical conditions. The spectra are mostly broad with mean Doppler shifts close to zero (type II spectra). The typical groupings of type I and type III spectra are clearly identified. All types appear to be in general much more symmetric than those recorded with SABRE, and the skewness is only weakly dependent on the sign of the mean Doppler shift. Its distribution peaks near zero and shows a weak positive correlation with the type II Doppler shifts while the mostly positive type I Doppler shifts are slightly negatively correlated with the skewness.

  13. Experimental characterization of a vector Doppler system based on a clinical ultrasound scanner.

    PubMed

    Eranki, Avinash; Sikdar, Siddhartha

    2009-01-01

    We have developed a vector Doppler system using a clinical ultrasound scanner with a research interface. In this system, vector Doppler estimation is performed by electronically dividing a linear array transducer into a transmit sub-aperture and two receive sub-apertures. The receive beams are electronically steered, and two velocity components are estimated from echoes received from the beam overlap region. The velocity vector is reconstructed from these two estimates. The goal of this study was to characterize this vector Doppler system in vitro using a string phantom with a pulsatile velocity waveform. We studied the effect of four parameters on the estimation error: beam steering angle, angle of the velocity vector, depth of the scatterer relative to the beam overlap region and the transmit focus depth. Our results show that changing these parameters have minimal effect on the velocity and angle estimates, and robust velocity vector estimates can be obtained under a variety of conditions. The mean velocity error was less than 0.06 x pulse repetition frequency. The velocity estimates are sensitive to the Doppler estimation method. Our results indicate that vector Doppler using a linear array transducer is feasible for a wide range of imaging parameters. Such a system would facilitate the investigation of complex blood flow and tissue motion in human subjects.

  14. Transcranial power M-mode Doppler ultrasound for diagnosis of patent foramen ovale

    NASA Astrophysics Data System (ADS)

    Moehring, Mark; Spencer, Merrill

    2005-04-01

    Patent foramen ovale (PFO) is a right-to-left shunt (RLS) which communicates blood from the right to left atrium of the heart. PFO has been associated with stroke and, more recently, with migraine headache. Diagnosis of RLS can be accomplished effectively with transcranial power M-mode Doppler ultrasound (PMD). PMD is a modality which can be performed without the sedation required by the more invasive diagnostic technique using transesophageal echocardiography. PMD for this application consists of 2 MHz pulse Doppler ultrasound with placement of sample gates at 2 mm intervals along the single-transducer beam axis, and 8 kHz pulse repetition rate (PMD100M, Spencer Technologies). Doppler power versus depth is constructed every 4ms, using 33 sample gates. Bubble microemboli injected in the venous system and moving across a PFO present as high intensity tracks on a PMD image, as emboli transit from the heart to the brain and through the observed cerebral vasculature. Use of PMD in this context has been reported in the clinical literature [M. P. Spencer, M. A. Moehring, J. Jesurum et al, J. Neuroimaging 14, 342-349 (2004)]. This talk surveys the basic technical features of PMD for sensing PFO-related showers of bubble microemboli, and how these features provide clues to the severity of PFO.

  15. The removal of wall components in Doppler ultrasound signals by using the empirical mode decomposition algorithm.

    PubMed

    Zhang, Yufeng; Gao, Yali; Wang, Le; Chen, Jianhua; Shi, Xinling

    2007-09-01

    Doppler ultrasound systems, used for the noninvasive detection of the vascular diseases, normally employ a high-pass filter (HPF) to remove the large, low-frequency components from the vessel wall from the blood flow signal. Unfortunately, the filter also removes the low-frequency Doppler signals arising from slow-moving blood. In this paper, we propose to use a novel technique, called the empirical mode decomposition (EMD), to remove the wall components from the mixed signals. The EMD is firstly to decompose a signal into a finite and usually small number of individual components named intrinsic mode functions (IMFs). Then a strategy based on the ratios between two adjacent values of the wall-to-blood signal ratio (WBSR) has been developed to automatically identify and remove the relevant IMFs that contribute to the wall components. This method is applied to process the simulated and clinical Doppler ultrasound signals. Compared with the results based on the traditional high-pass filter, the new approach obtains improved performance for wall components removal from the mixed signals effectively and objectively, and provides us with more accurate low blood flow.

  16. Sonographic imaging of extra-testicular focal lesions: comparison of grey-scale, colour Doppler and contrast-enhanced ultrasound

    PubMed Central

    Rafailidis, Vasileios; Robbie, Hasti; Konstantatou, Eleni; Huang, Dean Y; Deganello, Annamaria; Sellars, Maria E; Cantisani, Vito; Isidori, Andrea M

    2016-01-01

    Extra-testicular lesions are usually benign but present with nonspecific grey-scale sonography findings. This study assesses conventional sonographic characteristics in the differentiation of extra-testicular tumoural from inflammatory lesions and whether contrast-enhanced ultrasound has a role. A retrospective database analysis was performed. All patients were examined by experienced sonographers employing standard techniques combining grey-scale, colour Doppler sonography and contrast-enhanced ultrasound. Features recorded were: clinical symptoms, size, location, echogenicity, colour Doppler sonography and contrast-enhanced ultrasound enhancement. Vascularity on colour Doppler sonography and contrast-enhanced ultrasound was graded and compared. The lesions were classified as tumoural or inflammatory. The Chi-square test was used to analyse the sonographic patterns and kappa coefficient to measure the agreement between colour Doppler sonography and contrast-enhanced ultrasound. A total of 30 lesions were reviewed (median diameter 12 mm, range 5–80 mm, median age 52 years, range 18–86 years), including 13/30 tumoural and 17/30 inflammatory lesions. Lesions were hypoechoic (n = 12), isoechoic (n = 6), hyperechoic (n = 2) or mixed (n = 10). Grey-scale characteristics of tumoural vs. inflammatory lesions differed significantly (P = 0.026). On colour Doppler sonography, lesions had no vessels (n = 16), 2–3 vessels (n = 10) and ≥4 vessels (n = 4). On contrast-enhanced ultrasound, lesions showed no vascularity (n = 17), perfusion similar to testis (n = 7) and higher (n = 6). All abscesses identified (n = 9) showed no vascularity on both colour Doppler sonography and contrast-enhanced ultrasound. There was good agreement between these techniques in evaluating vascularity (κ = 0.719) and no significant difference between colour Doppler sonography and contrast-enhanced ultrasound of tumoural vs. inflammatory

  17. Investigations of spectral resolution and angle dependency in a 2-D tracking Doppler method.

    PubMed

    Fredriksen, Tonje D; Avdal, Jorgen; Ekroll, Ingvild K; Dahl, Torbjorn; Lovstakken, Lasse; Torp, Hans

    2014-07-01

    An important source of error in velocity measurements from conventional pulsed wave (PW) Doppler is the angle used for velocity calibration. Because there are great uncertainties and interobserver variability in the methods used for Doppler angle correction in the clinic today, it is desirable to develop new and more robust methods. In this work, we have investigated how a previously presented method, 2-D tracking Doppler, depends on the tracking angle. A signal model was further developed to include tracking along any angle, providing velocity spectra which showed good agreement with both experimental data and simulations. The full-width at half-maximum (FWHM) bandwidth and the peak value of predicted power spectra were calculated for varying tracking angles. It was shown that the spectra have lowest bandwidth and maximum power when the tracking angle is equal to the beam-to-flow angle. This may facilitate new techniques for velocity calibration, e.g., by manually adjusting the tracking angle, while observing the effect on the spectral display. An in vitro study was performed in which the Doppler angles were predicted by the minimum FWHM and the maximum power of the 2-D tracking Doppler spectra for 3 different flow angles. The estimated Doppler angles had an overall error of 0.24° ± 0.75° when using the minimum FWHM. With an in vivo example, it was demonstrated that the 2-D tracking Doppler method is suited for measurements in a patient with carotid stenosis.

  18. Image analysis of placental issues using three-dimensional ultrasound and color power doppler

    NASA Astrophysics Data System (ADS)

    Wang, Qi; Cheng, Qiong; Liu, J. G.

    2007-12-01

    With the development of birthing-process medical science, and insurance requirement of prepotency, the ultrasound technique is widely used in the application of obstetrics realm, especially on the monitoring of embryo's growth. In the recent decade, the introduction of high resolution three-dimensional ultrasonic and color power Doppler scanner provides a much more direct, sensitive, forerunner method for the monitoring of embryo and gravida's prediction. A novel method that depends on examining images of vasculature of placenta to determine the growth of embryo is introduced in this paper. First, get a set of placenta vascularity images of the pregnant woman, taken by Color Doppler Ultrasonic Scanner, then mark some points in these images, where we get a section image, thus we can observe the internal blood vessel distribution at those points. This method provides an efficient tool for doctors.

  19. INFLUENCE OF DOPPLER WIDTH FLUCTUATIONS ON THE SHAPE OF SPECTRAL LINES

    SciTech Connect

    Silant'ev, N. A.; Lekht, E. E.; Alexeeva, G. A.

    2009-05-10

    We investigate the influence of stochastic Doppler width fluctuations on the shape of spectral lines. The photospheres and atmospheres of stars, and the interstellar medium, possess stochastic behavior especially near nonstationary objects such as active galactic nuclei, quasars, flare stars, and regions of star formation. In reality, we observe the mean values of intensities from these objects. In most situations, the spectral line extinction coefficient has a Gaussian shape with the stochastic Doppler width determined by thermal and small-scale turbulent motions of atoms or molecules. For small-scale turbulent motions (short-correlated turbulence) the propagation of radiation is described by the average extinction factor. This coefficient depends on the level of the Doppler width fluctuations {eta}. We show that these fluctuations change both the value of intensity and the shape of spectral lines. We consider distortions of the spectral line shapes for the absorption and emission lines for various values of the parameter {eta}. For a number of H{sub 2}O maser sources we estimate the values of this parameter, the optical depths of the inverted media, and the mean effective Doppler velocities. Maser emission lines with non-Gaussian shape can serve as an additional method for the investigation of the physical parameters in maser 'spots'.

  20. Limited Accuracy of Colour Doppler Ultrasound Dynamic Tissue Perfusion Measurement in Diabetic Adults

    PubMed Central

    Stoperka, Felix; Karger, Claudia

    2016-01-01

    Dynamic tissue perfusion measurement (DTPM) is a pre-described and available method in pediatric ultrasound to quantify tissue perfusion in renal Doppler ultrasound by particular video analysis software. This study evaluates DTPM during single and between repeated visits after 6 months, calibrates repeated DTPM within different region of interest (ROI) and compares DTPM with kidney function markers in adult patients with early diabetic nephropathy (n = 17). During repeated measurements, no association of readings at the same patients in the same (n = 3 readings) as well as repeated visit (n = 2 visits) could be retrieved. No association between DTPM, MDRD-GFR, albuminuria, age and duration of diabetes was observed. These negative results are presumably related to inconsistency of DTPM due to non-fixed ROI position as could be shown in calibrating series. Further development of the method should be performed to enable reproducible DTPM readings in adults. PMID:28033403

  1. [Duplex ultrasound and color-coded Doppler ultrasound of visceral blood vessels in abdominal diseases].

    PubMed

    Mostbeck, G; Mallek, R; Gebauer, A; Tscholakoff, D

    1992-01-01

    Duplex Doppler sonography (DS) and color-flow Doppler sonography (FDS) are noninvasive diagnostic methods for the evaluation of a patient with suspected vascular disease of the abdomen. They represent a useful adjunct to realtime sonography in the identification of normal and variant visceral vascular anatomy. Aneurysms and pseudo-aneurysms of visceral arteries are readily differentiated from other cystic lesions. DS and FDS have a high sensitivity in the detection of portal vein thrombosis and stenosis. Both methods allow the observation and measurement of splanchnic hemodynamics in patients with chronic liver disease and portal hypertension. Hence, DS and FDS already play an important role in the pre- and postoperative assessment of patients undergoing liver or pancreas transplantation. The possibility that DS and FDS may enable discrimination between hypovascular and hypervascular tumors is under clinical investigation. FDS facilitates an excellent anatomic display of the abdominal vasculature and allows easy placement of the Doppler sample volume. Consequently, quantitative data acquired with DS are accomplished within short scanning times. However, the diagnostic impact of both modalities depends to a great extent on the experience of the investigator.

  2. Time-resolved measurement of bubble cavitation by using power Doppler ultrasound image

    NASA Astrophysics Data System (ADS)

    Koda, Ren; Izumi, Yosuke; Nagai, Hayato; Yamakoshi, Yoshiki

    2017-04-01

    In this study, a novel measurement method for a secondary ultrasound wave irradiated by microbubble cavitation is proposed. High-intensity ultrasound (h-US, 1.0–1.5 MPa), which produces bubble cavitation, is irradiated with a fixed time delay after introducing imaging US, whose frequency is different from that of the h-US. The bubble cavitation signal (BCS) is detected by the signal-processing unit of an ultrasound power Doppler imaging instrument. By this method, both a spatially resolved bubble image (S-image) and the temporal transition of the BCS (T-image) are monitored simultaneously. A feature of the method is that the BCS is observed in situ with sub-µs time resolution. The accuracy of the method is evaluated and it is found that the maximum deviation of the amplitude of the simulated BCS is 4.80%. This method is applied to measure the BCS of ultrasound contrast agent microbubbles. As a result, the dependence of the inherent temporal transition of the BCS on the sound pressure of the h-US (0.6–1.2 MPa) is observed.

  3. On the role of spectral resolution in velocity shear layer measurements by Doppler reflectometry

    SciTech Connect

    Happel, T.; Blanco, E.; Estrada, T.

    2010-10-15

    The signal quality of a Doppler reflectometer depends strongly on its spectral resolution, which is influenced by the microwave beam properties and the radius of curvature of the cutoff layer in the plasma. If measured close to a strong perpendicular velocity shear layer, the spectrum of the backscattered signal is influenced by different velocities. This can give rise to two Doppler shifted peaks in the spectrum as observed in TJ-II H-mode plasmas. It is shown by two-dimensional full wave simulations that the two peaks are separable provided the spectral resolution of the system is sufficient. However, if the spectral resolution is poor, the two peaks blend into one and yield an intermediate and incorrect velocity.

  4. Neovascularity in patellar tendinopathy and the response to eccentric training: a case report using Power Doppler ultrasound.

    PubMed

    McCreesh, Karen M; Riley, Sara J; Crotty, James M

    2013-12-01

    This report describes the case of an amateur soccer player with chronic patellar tendinopathy who underwent ultrasound imaging before and after engaging in an 8-week programme of eccentric exercise. On initial assessment, greyscale ultrasound imaging demonstrated tendon thickening and reduced echogenicity, while Power Doppler imaging demonstrated a large amount of neovascularity. After 8 weeks of an eccentric loading programme, the patient reported significantly improved symptoms and functional scores, while follow-up imaging demonstrated improvement in the echo appearance of the tendon and complete resolution of the neovascularity. The association between neovascularity and symptoms in tendinopathy research is conflicting, with a paucity of research in the area of patellar tendinopathy. While further research is needed to clarify the significance of greyscale and Power Doppler ultrasound changes in relation to symptoms in patellar tendinopathy, ultrasound imaging was shown to be a useful adjunct to diagnosis and outcome assessment in this case.

  5. New adaptive clutter rejection for ultrasound color Doppler imaging: in vivo study.

    PubMed

    Yoo, Yang Mo; Kim, Yongmin

    2010-03-01

    Clutter rejection is essential for accurate flow estimation in ultrasound color Doppler imaging. In this article, we present a new adaptive clutter rejection (ACR) technique where an optimum filter is dynamically selected depending upon the underlying clutter characteristics (e.g., tissue acceleration and power). We compared the performance of the ACR method with other adaptive methods, i.e., down-mixing (DM) and adaptive clutter filtering (ACF), using in vivo data acquired from the kidney, liver and common carotid artery. With the kidney data, the ACR method provided an average improvement of 3.05 dB and 1.7 dB in flow signal-to-clutter ratio (SCR) compared with DM and ACF, respectively. With the liver data, SCR was improved by 2.75 dB and 1.8 dB over DM and ACF while no significant improvement with ACR was found in the common carotid artery data. Thus, the proposed adaptive method could provide more accurate flow estimation by improving clutter rejection in abdominal ultrasound color Doppler imaging pending validation.

  6. Renal transplantation parenchymal complications: what Doppler ultrasound can and cannot do.

    PubMed

    Granata, Antonio; Di Nicolò, Pierpaolo; Scarfia, Viviana R; Insalaco, Monica; Lentini, Paolo; Veroux, Massimiliano; Fatuzzo, Pasquale; Fiorini, Fulvio

    2015-06-01

    Kidney transplantation is the treatment of choice in end-stage renal disease, given the better quality of life of transplanted patients when compared with patients on maintenance dialysis. In spite of surgical improvements and new immunosuppressive regimens, parts of transplanted grafts still develop chronic dysfunction. Ultrasonography, both in B-mode and with Doppler ultrasound, is an important diagnostic tool in case of clinical conditions which might impair kidney function. Even though ultrasonography is considered fundamental in the diagnosis of vascular and surgical complications of the transplanted kidney, its role is not fully understood in case of parenchymal complications of the graft. The specificity of Doppler is low both in case of acute complications, such as acute tubular necrosis, drugs toxicity and acute rejection, and in case of chronic conditions, such as chronic allograft nephropathy. Single determinations of resistance indices present low diagnostic accuracy, which is higher in case of successive measurements performed during the follow-up of the graft. Modern techniques such as tissue pulsatility index, maximal fractional area and contrast-enhanced ultrasound increase ultrasonography diagnostic power in case of parenchymal complications of the transplanted kidney.

  7. B-mode Ultrasound Versus Color Doppler Twinkling Artifact in Detecting Kidney Stones

    PubMed Central

    Harper, Jonathan D.; Hsi, Ryan S.; Shah, Anup R.; Dighe, Manjiri K.; Carter, Stephen J.; Moshiri, Mariam; Paun, Marla; Lu, Wei; Bailey, Michael R.

    2013-01-01

    Abstract Purpose To compare color Doppler twinkling artifact and B-mode ultrasonography in detecting kidney stones. Patients and Methods Nine patients with recent CT scans prospectively underwent B-mode and twinkling artifact color Doppler ultrasonography on a commercial ultrasound machine. Video segments of the upper pole, interpolar area, and lower pole were created, randomized, and independently reviewed by three radiologists. Receiver operator characteristics were determined. Results There were 32 stones in 18 kidneys with a mean stone size of 8.9±7.5 mm. B-mode ultrasonography had 71% sensitivity, 48% specificity, 52% positive predictive value, and 68% negative predictive value, while twinkling artifact Doppler ultrasonography had 56% sensitivity, 74% specificity, 62% positive predictive value, and 68% negative predictive value. Conclusions When used alone, B-mode is more sensitive, but twinkling artifact is more specific in detecting kidney stones. This information may help users employ twinkling and B-mode to identify stones and developers to improve signal processing to harness the fundamental acoustic differences to ultimately improve stone detection. PMID:23067207

  8. Spectral energy measurements of simulated microemboli of various sizes using a diffraction grating ultrasound probe

    NASA Astrophysics Data System (ADS)

    Weiss, William J.; Ballakur, Sowmya G.; Tran, Hoang; Hazard, Sprague W.; Blebea, John

    2003-05-01

    This study characterizes the Doppler signal from simulated microemboli of various sizes in blood mimicking fluid using spectral energy parameters. The goal of this research is to detect microemboli as a non-invasive diagnostic tool, or intra-operatively as a surgical aid. A dual beam diffraction-grating ultrasound probe operating at 10 MHz (Model Echoflow BVM-1, EchoCath, Inc., Princeton, NJ) was used with a flow phantom. Microemboli were polystyrene microspheres in 200 to 1000 micron diameters, in concentrations of 0.1, 0.5, and 1.0 per ml. Average flow velocities were 25, 50, 75, and 100 cm/sec. The distribution of peak values of the power spectrum at 2.5 msec windows was plotted over 15 seconds. The means of the distributions corresponding to the microspheres and background fluid were averaged for the four velocity conditions. Embolic peak spectral power ranged from approximately 12 to 25 dB relative to the background. A detection method based on these measurements is currently being developed.

  9. Audio spectrum analysis of umbilical artery Doppler ultrasound signals applied to a clinical material.

    PubMed

    Thuring, Ann; Brännström, K Jonas; Jansson, Tomas; Maršál, Karel

    2014-12-01

    Analysis of umbilical artery flow velocity waveforms characterized by pulsatility index (PI) is used to evaluate fetoplacental circulation in high-risk pregnancies. However, an experienced sonographer may be able to further differentiate between various timbres of Doppler audio signals. Recently, we have developed a method for objective audio signal characterization; the method has been tested in an animal model. In the present pilot study, the method was for the first time applied to human pregnancies. Doppler umbilical artery velocimetry was performed in 13 preterm fetuses before and after two doses of 12 mg betamethasone. The auditory measure defined by the frequency band where the spectral energy had dropped 15 dB from its maximum level (MAXpeak-15 dB ), increased two days after betamethasone administration (p = 0.001) parallel with a less pronounced decrease in PI (p = 0.04). The new auditory parameter MAXpeak-15 dB reflected the changes more sensitively than the PI did.

  10. Comparison of dynamic contrast enhanced MRI and Doppler ultrasound in the pre-operative assessment of the portal venous system.

    PubMed

    Naik, K S; Ward, J; Irving, H C; Robinson, P J

    1997-01-01

    The purpose of this study was to compare dynamic contrast enhanced MRI (DCEMR) with Doppler ultrasound (US) in the assessment of portal venous anatomy and to analyse the causes of discrepancy. Over a 1 year period, 97 patients undergoing assessment prior to hepatic surgery underwent imaging of the liver and portal venous system using US with colour and spectral Doppler and MRI with axial T2 weighted spin echo (SE) and coronal oblique T1 weighted rapid gradient echo (GRE) imaging before and immediately after bolus injection of Gd-DTPA (0.1 mmol kg-1). When the US and MRI findings were discrepant, the images were reviewed by two observers and compared with surgical findings. US and DCEMR were concordant in 90 patients (portal vein patent in 80, occluded in 10). In three patients with cirrhosis and gross ascites the portal vein was reported as occluded on US and patent on MRI; surgery confirmed the MRI findings. In one patient the portal vein was patient on US but not on MRI, but there was a 3 week interval between the examinations. In three patients the portal vein was patent on US, but MRI detected occlusion of intrahepatic portal vein branches in two, and encasement of an intrahepatic branch in the third case. Spontaneous splenorenal shunts were seen in 15 patients only on MRI; varices were seen in 39 patients on MRI and in 22 patients on US. Both US and DCEMR contribute to the pre-operative assessment of the portal venous system. MRI provides additional information over US in assessing intrahepatic portal branches and detecting varices and splenorenal shunts, and is recommended for all surgical candidates and in patients with abnormal portal venous anatomy and equivocal US findings.

  11. Transvaginal 3-d power Doppler ultrasound evaluation of the fetal brain at 10-13 weeks' gestation.

    PubMed

    Hata, Toshiyuki; Tanaka, Hirokazu; Noguchi, Junko

    2012-03-01

    The objective of this study was to measure the fetal brain volume (FBV) and vascularization and blood flow using transvaginal 3-D power Doppler (3DPD) ultrasound late in the first trimester of pregnancy. 3DPD ultrasound examinations with the VOCAL imaging analysis program were performed on 36 normal fetuses from 10-13 weeks' gestation. FBV and 3DPD indices related to the fetal brain vascularization (vascularization index [VI], flow index [FI] and vascularization flow index [VFI]) were calculated in each fetus. Intra- and interclass correlation coefficients and intra- and interobserver agreements of measurements were assessed. FBV was curvilinearly correlated well with the gestational age (R2 = 0.861, p < 0.0001). All 3-D power Doppler indices (VI, FI and VFI) showed no change at 10-13 weeks' gestation. FBV and all 3-D power Doppler indices (VI, FI and VFI) showed a correlation > 0.82, with good intra- and interobserver agreement. Our findings suggest that 3-D ultrasound is a superior means of evaluating the FBV in utero, and that 3-D power Doppler ultrasound histogram analysis may provide new information on the assessment of fetal brain perfusion.

  12. Transcranial Doppler ultrasound in the diagnosis of brain death. Is it useful or does it delay the diagnosis?

    PubMed

    Escudero, D; Otero, J; Quindós, B; Viña, L

    2015-05-01

    Transcranial Doppler ultrasound is able to demonstrate cerebral circulatory arrest associated to brain death, being especially useful in sedated patients, or in those in which complete neurological exploration is not possible. Transcranial Doppler ulstrasound is a portable, noninvasive and high-availability technique. Among its limitations, mention must be made of the absence of acoustic windows and false-negative cases. In patients clinically diagnosed with brain death, with open skulls or with anoxia as the cause of death, cerebral blood flow can be observed by ultrasound, since cerebral circulatory arrest is not always synchronized to the clinical diagnosis. The diagnostic rate is therefore time-dependent, and this fact that must be recognized in order to avoid delays in death certification. Despite its limitations, transcranial Doppler ulstrasound helps solve common diagnostic problems, avoids the unnecessary consumption of resources, and can optimize organ harvesting for transplantation.

  13. Comparison of blood flow velocity through the internal carotid artery based on Doppler ultrasound and numerical simulation.

    PubMed

    Hassani-Ardekani, Hajar; Ghalichi, Farzan; Niroomand-Oscuii, Hanieh; Farhoudi, Mehdi; Tarzmani, Mohammad Kazem

    2012-12-01

    Doppler ultrasound is a usual non-invasive method to estimate the stenosis percentage in large arteries such as carotid by measuring maximum velocity of blood flow. Based on clinical investigations, because of vessel wall motions, Doppler positioning and angle correction, some errors can arise in Doppler results which lead to incorrect diagnosis. The aim of this study was to compare the results of Doppler test and the numerical simulation of blood flow in the same case. For this evaluation, two patients including an 87-year-old man and a 72-year-old woman suffering from stenosis in the internal carotid artery were selected. First, clinical information of each patient such as CT-Angio scan images and Doppler ultrasound results on different locations of the stenosed artery were obtained. Then, the geometries were reconstructed and numerical simulations were carried out using ANSYS software. Results showed that the velocity profile of Doppler test and numerical simulation were in good agreement at the regions of pre-and post-stenosis. However, the value of maximum velocity at the stenotic region had significant differences.

  14. Comparison between ultrasonographic findings of benign and malignant canine mammary gland tumours using B-mode, colour Doppler, power Doppler and spectral Doppler.

    PubMed

    Soler, Marta; Dominguez, Elisabet; Lucas, Xiomara; Novellas, Rosa; Gomes-Coelho, Kassia Valeria; Espada, Yvonne; Agut, Amalia

    2016-08-01

    The aim of this study was to evaluate whether the comparison between the ultrasonographic features of canine mammary tumours, assessed by B-Mode, colour Doppler, power Doppler, spectral Doppler, and histopathologic features, would help to differentiate if a tumour is benign or malignant. Ultrasonographic examinations of 104 tumours were performed. Volume, margins, presence of a capsule, echotexture and presence and distribution of the vascular flow of the tumours were evaluated. All the tumours were surgically removed, submitted for histopathologic examination and classified in two groups: Group I (benign tumours) and Group II (malignant tumours). Echotexture was the only parameter evaluated by B-Mode ultrasonography where significant differences were found (p<0.01), with tumours in Group I being homogeneous and tumours in Group II presenting greater heterogeneity. Presence of vascular flow was observed in most of the tumours from both groups and no differences between them were found. Regarding flow distribution, significant differences were observed between groups (p<0.05). In benign tumours, the most common vascular pattern was the peripheral, showing significant differences (p<0.05) compared to mixed and central patterns. In malignant tumours the mixed pattern was the most frequent. Also significant differences among other patterns (peripheral and central) were found. Concerning vascular resistivity and pulsatility indexes, there were no significant differences between the two groups. The echotexture and type of vascular flow pattern of canine mammary gland tumours may help, in a first examination of the tumour, to differentiate between benign and malignant tumours; however to reach a definitive diagnosis histological study is required.

  15. Acoustical imaging and processing of blood vessel and the related materials using ultrasound Doppler effect.

    PubMed

    Yokobori, A T; Ohkuma, T; Yoshinari, H; Yokobori, T; Ohuchi, H; Mori, S

    1991-01-01

    In the present paper a method is proposed to measure the degree of the degradation of the elasticity in natural blood vessel and the related materials by using ultrasound Doppler effect. It was found that the deformation rate and its acceleration in the radial direction of the blood vessel can be detected by acoustical imaging and processing using this method. These results were proven to correspond to the degree of the degradation of the elasticity, that is, the degree of viscoelasticity in the blood vessel from the wave versus time pattern detected and its simple analysis. This method was applied to predicting the arteriosclerosis of blood vessels of humans by acoustical imaging and processing uninvadedly, as the characteristics of viscoelasticity in blood vessels.

  16. Modelflow Estimates of Stroke Volume Do Not Correlate With Doppler Ultrasound Estimates During Upright Posture

    NASA Technical Reports Server (NTRS)

    Ferguson, Connor R.; Lee, Stuart M. C.; Stenger, Michael B.; Platts, Steven H.; Laurie, Steven S.

    2014-01-01

    Orthostatic intolerance affects 60-80% of astronauts returning from long-duration missions, representing a significant risk to completing mission-critical tasks. While likely multifactorial, a reduction in stroke volume (SV) represents one factor contributing to orthostatic intolerance during stand and head up tilt (HUT) tests. Current measures of SV during stand or HUT tests use Doppler ultrasound and require a trained operator and specialized equipment, restricting its use in the field. BeatScope (Finapres Medical Systems BV, The Netherlands) uses a modelflow algorithm to estimate SV from continuous blood pressure waveforms in supine subjects; however, evidence supporting the use of Modelflow to estimate SV in subjects completing stand or HUT tests remain scarce. Furthermore, because the blood pressure device is held extended at heart level during HUT tests, but allowed to rest at the side during stand tests, changes in the finger arterial pressure waveform resulting from arm positioning could alter modelflow estimated SV. The purpose of this project was to compare Doppler ultrasound and BeatScope estimations of SV to determine if BeatScope can be used during stand or HUT tests. Finger photoplethysmography was used to acquire arterial pressure waveforms corrected for hydrostatic finger-to-heart height using the Finometer (FM) and Portapres (PP) arterial pressure devices in 10 subjects (5 men and 5 women) during a stand test while simultaneous estimates of SV were collected using Doppler ultrasound. Measures were made after 5 minutes of supine rest and while subjects stood for 5 minutes. Next, SV estimates were reacquired while each arm was independently raised to heart level, a position similar to tilt testing. Supine SV estimates were not significantly different between all three devices (FM: 68+/-20, PP: 71+/-21, US: 73+/-21 ml/beat). Upon standing, the change in SV estimated by FM (-18+/-8 ml) was not different from PP (-21+/-12), but both were significantly

  17. Evaluation of a fractional filter-based receive beamforming method for low-cost ultrasound color Doppler imaging

    NASA Astrophysics Data System (ADS)

    Yang, Hana; Kang, Jeeun; Chang, Jin Ho; Yoo, Yangmo

    2012-03-01

    In medical ultrasound imaging, dynamic receive beamforming has been used for improving signal-to-noise ratio (SNR) and spatial resolution. For low-cost portable ultrasound imaging systems, a fractional filter-based receive beamforming (FFRB) method was previously proposed to reduce the hardware complexity compared to conventional interpolation filter-based receive beamforming methods (IFRB). While this new beamforming method substantially reduces the hardware complexity, it yields the nonlinear phase response for high frequencies due to the limited length of fractional filter coefficients, leading to the bias on flow estimation in ultrasound color Doppler imaging. In this paper, to evaluate the FFRB method for ultrasound color Doppler imaging, the Field II simulation and string phantom experiments were conducted. In Field II simulation, the radio-frequency (RF) data were generated by assuming a 7.5-MHz linear array probe with the transmit frequency of 6 MHz, the ensemble size of 8, and the sampling frequencies of 20 MHz. In string phantom experiments, the RF channel data were obtained with a commercial SonixTouch ultrasound scanner equipped with a research package (Ultrasonix Corp., Vancouver, BC, Canada; a 5-MHz linear array connected to a SonixDAQ parallel system. The ensemble size and the sampling frequency were set to 10 and 20 MHz, respectively. For the Field II simulation and string phantom experiments, only 1.2% and 2.3 % in color Doppler estimation error ratio was observed with mean and standard deviation along the lateral direction. This result indicates that the proposed FFRB method could be utilized for a low-cost ultrasound color Doppler imaging system with lowered hardware complexity and minimized phase errors.

  18. Prevalence in a volunteer population of pelvic cancer detected with transvaginal ultrasound and color flow Doppler.

    PubMed

    Schulman, H; Conway, C; Zalud, I; Farmakides, G; Haley, J; Cassata, M

    1994-09-01

    Our objective was to find the prevalence of non-symptomatic endometrial and ovarian neoplasms in a volunteer population of women, aged 40 and over. We offered a free volunteer screening program to asymptomatic women for a study using transvaginal ultrasound and color flow Doppler for the detection of pelvic cancer. In the first 2 years, 2117 women were examined, 51.3% post-menopausal. An ovarian cyst was defined as having a maximum diameter of more than 2.4 cm. Color flow was used to identify blood vessels feeding pelvic organs and adnexal enlargements. An abnormal Doppler flow velocity for the ovary was defined as a resistance index of less than 0.41. Ovarian cysts of less than 5 cm with normal Doppler indices were followed up in 6 months to 1 year. An adnexal morphology score was created to quantify the usefulness of this parameter, particularly in postmenopausal women. Indications for surgery were pre-defined as a persistent ovarian cyst of more than 5 cm, a persistent suspicious Doppler and a total endometrial thickness of greater than 0.59 cm in postmenopausal women not taking hormones.A total of 202 women (9.5%) had ovarian cysts. Fourteen women were operated upon because of size criteria, one because of family history and three for persistent abnormal flow. By Doppler study, 15 cysts were predicted to be benign and histology was confirmatory. There were two false positives and one true positive, a stage Ib ovarian cancer. There were no false negatives, although a stage I endometrioid cancer of the ovary was detected 8 months after a negative scan. In those cases in which follow-up data were available, 56% of the cysts regressed in premenopausal women. In postmenopausal women, 28% regressed. Twenty of 1086 postmenopausal women had endometrial biopsies. Three had endometrial cancer, two stage I and one stage IIA. Five had atypical or adenomatous hyperplasia, and seven had benign polyps. So many women have small asymptomatic cysts of the ovary that a major

  19. Doppler ultrasound compatible plastic material for use in rigid flow models.

    PubMed

    Wong, Emily Y; Thorne, Meghan L; Nikolov, Hristo N; Poepping, Tamie L; Holdsworth, David W

    2008-11-01

    A technique for the rapid but accurate fabrication of multiple flow phantoms with variations in vascular geometry would be desirable in the investigation of carotid atherosclerosis. This study demonstrates the feasibility and efficacy of implementing numerically controlled direct-machining of vascular geometries into Doppler ultrasound (DUS)-compatible plastic for the easy fabrication of DUS flow phantoms. Candidate plastics were tested for longitudinal speed of sound (SoS) and acoustic attenuation at the diagnostic frequency of 5 MHz. Teflon was found to have the most appropriate SoS (1376 +/- 40 m s(-1) compared with 1540 m s(-1) in soft tissue) and thus was selected to construct a carotid bifurcation flow model with moderate eccentric stenosis. The vessel geometry was machined directly into Teflon using a numerically controlled milling technique. Geometric accuracy of the phantom lumen was verified using nondestructive micro-computed tomography. Although Teflon displayed a higher attenuation coefficient than other tested materials, Doppler data acquired in the Teflon flow model indicated that sufficient signal power was delivered throughout the depth of the vessel and provided comparable velocity profiles to that obtained in the tissue-mimicking phantom. Our results indicate that Teflon provides the best combination of machinability and DUS compatibility, making it an appropriate choice for the fabrication of rigid DUS flow models using a direct-machining method.

  20. In vitro Doppler ultrasound investigation of turbulence intensity in pulsatile flow with simulated cardiac variability.

    PubMed

    Thorne, Meghan L; Poepping, Tamie L; Nikolov, Hristo N; Rankin, Richard N; Steinman, David A; Holdsworth, David W

    2009-01-01

    An in vitro investigation of turbulence intensity (TI) associated with a severe carotid stenosis in the presence of physiological cardiac variability is described. The objective of this investigation was to determine if fluctuations due to turbulence could be quantified with conventional Doppler ultrasound (DUS) in the presence of normal physiological cycle-to-cycle cardiac variability. An anthropomorphic model of a 70% stenosed carotid bifurcation was used in combination with a programmable flow pump to generate pulsatile flow with a mean flow rate of 6 mL/s. Utilizing the pump, we studied normal, nonrepetitive cycle-to-cycle cardiac variability (+/-3.9%) in flow, as well as waveform shapes with standard deviations equal to 0, 2 and 3 times the normal variation. Eighty cardiac cycles of Doppler data were acquired at two regions within the model, representing either laminar or turbulent flow; each measurement was repeated six times. Turbulence intensity values were found to be 11 times higher (p < 0.001), on average, in the turbulent region than in the laminar region, with a mean difference of 24 cm/s. Twenty cardiac cycles were required for confidence in TI values. In conclusion, these results indicate that it is possible to quantify TI in vitro, even in the presence of normal and exaggerated cycle-to-cycle cardiac variability.

  1. Doppler ultrasound in vitro modeling of turbulence in carotid vascular disease

    NASA Astrophysics Data System (ADS)

    Thorne, Meghan L.; Poepping, Tamie L.; Rankin, Richard N.; Nikolov, Hristo N.; Holdsworth, David W.

    2004-04-01

    Turbulence is ubiquitous to many systems in nature, except the human vasculature. Development of turbulence in the human vasculature is an indication of abnormalities and disease. A severely stenosed vessel is one such example. In vitro modeling of common vascular diseases, such as a stenosis, is necessary to develop a better understanding of the fluid dynamics for a characteristic geometry. Doppler ultrasound (DUS) is the only available non-invasive technique for in vivo applications. Using Doppler velocity-derived data, turbulence intensity (TI) can be calculated. We investigate a realistic 70% stenosed bifurcation model in pulsatile flow and the performance of this model for turbulent flow. Blood-mimicking fluid (BMF) was pumped through the model using a flow simulator, which generated pulsatile flow with a mean flow rate of 6 ml/s. Twenty-five cycles of gated DUS data were acquired within regions of laminar and turbulent flow. The data was digitized at 44.1 kHz and analyzed at 79 time-points/cardiac cycle with a 1024-point FFT, producing a 1.33 cm/s velocity resolution. We found BMF to exhibit DUS characteristics similar to blood. We demonstrated the capabilities to generate velocities comparable to that found in the human carotid artery and calculated TI in the case of repetitive pulsatile flow.

  2. [Ultrasound and color Doppler applications in nephrology. The normal kidney: anatomy, vessels and congenital anomalies].

    PubMed

    Meola, Mario; Petrucci, Ilaria; Giovannini, Lisa; Samoni, Sara; Dellafiore, Carolina

    2012-01-01

    Gray-scale ultrasound is the diagnostic technique of choice in patients with suspected or known renal disease. Knowledge of the normal and abnormal sonographic morphology of the kidney and urinary tract is essential for a successful diagnosis. Conventional sonography must always be complemented by Doppler sampling of the principal arterial and venous vessels. B-mode scanning is performed with the patient in supine, prone or side position. The kidney can be imaged by the anterior, lateral or posterior approach using coronal, transverse and oblique scanning planes. Morphological parameters that must be evaluated are the coronal diameter, the parenchymal thickness and echogenicity, the structure and state of the urinary tract, and the presence of congenital anomalies that may mimic a pseudomass. The main renal artery and the hilar-intraparenchymal branches of the arterial and venous vessels should be accurately evaluated using color Doppler. Measurement of intraparenchymal resistance indices (IP, IR) provides an indirect and quantitative parameter of the stiffness and eutrophic or dystrophic remodeling of the intrarenal microvasculature. These parameters differ depending on age, diabetic and hypertensive disease, chronic renal glomerular disease, and interstitial, vascular and obstructive nephropathy.

  3. Doppler ultrasound in kidney diseases: a key parameter in clinical long-term follow-up.

    PubMed

    Spatola, Leonardo; Andrulli, Simeone

    2016-12-01

    Doppler ultrasound has been extensively used in detecting reno-vascular diseases, showing to be a non-invasive, safe, low cost and repeatable tool. The Renal Resistive Index (RRI) [(peak systolic velocity - end diastolic velocity)/peak systolic velocity] is a semi-quantitative index derived by Doppler evaluation of renal vascular bed. Normally RRI is in the range of 0.47-0.70, it increases with aging and, usually, it shows a difference between the two kidneys less than 5-8 %. RRI is an important prognostic marker in chronic kidney diseases (CKD), both in diabetic and non-diabetic kidney diseases, because, in longitudinal prospective studies, it significantly correlated with hemodynamic (ABPM, SBP, DBP, pulse pressure) and histopathological parameters (glomerular sclerosis, arteriolosclerosis, interstitial fibrosis/tubular atrophy, interstitial infiltration). In acute kidney injury (AKI) RI is a valid tool in differentiating between pre-renal and renal failure and in predicting renal response to vaso-active agents. In addition a RRI >0.74 can predict the onset of AKI in septic patients. Renal Resistive Index is a useful marker in allograft diseases because it has been widely showed a correlation with histological lesions during worsening of renal function, both in acute rejection and in chronic allograft nephropathy. Recent studies suggest its role in the risk of new onset diabetes after transplantation and it could be one of the parameters to evaluate to shift or withdrawal immunological and/or hypertensive therapy.

  4. Arterial pulse wave propagation velocity in healthy dogs by pulse wave Doppler ultrasound.

    PubMed

    Nogueira, Rodrigo B; Pereira, Lucas A; Basso, Alice F; da Fonseca, Ingrid S; Alves, Lorena A

    2017-03-01

    The aim of this study was to prospectively evaluate the carotid-femoral pulse wave velocity (PWV) values in healthy dogs using pulse wave Doppler ultrasound. A secondary aim was to determine the feasibility of this method and to report the intra- and interobserver reproducibilities of the PWV in conscious dogs. The data were studied in 30 healthy, adult, male (n = 15) and female (n = 15) dogs. The time interval marked between the R wave peak of the electrocardiogram and the intersection of the blood flow wave upstroke of the Doppler spectrum with the baseline of zero frequency was determined for the carotid (T1) and for the femoral (T2) arteries. The distance covered by the pulse wave (L) was determined. The PWV was then calculated using the following formula: L/T2 - T1. The mean values of PWV calculated from the total sample (n = 30) evaluated were 13.41 ± 2.20 m/s. No significant statistical difference was observed for the PWV measurements between males (14.82 ± 3.18 m/s) and females (12.64 ± 2.45 m/s). The analysis revealed no intra nor interobserver differences. A reasonable reproducibility of the PWV measurements was showed by intraclass correlation coefficients (ICC), and the coefficients of variation (CV). These data demonstrate that noninvasive vascular Doppler analysis is a feasible and reproducible method to determine the carotid-femoral PWV in dogs.

  5. Field Evaluation in Four NEEMO Divers of a Prototype In-suit Doppler Ultrasound Bubble Detector

    NASA Technical Reports Server (NTRS)

    Acock, K. E.; Gernhardt, M. L.; Conkin, J.; Powell, M. R.

    2004-01-01

    It is desirable to know if astronauts produce venous gas emboli (VGE) as a result of their exposure to 4.3 psia during space walks. The current prototype in-suit Doppler (ISD) ultrasound bubble detector provides an objective assessment of decompression stress by monitoring for VGE. The NOAA Aquarius habitat and NASA Extreme Environment Mission Operations (NEEMO) series of dives provided an opportunity to assess the ability of the prototype ISDs to record venous blood flow and possibly detect VGE in the pulmonary artery. From July 16 to 29,2003, four aquanauts (two males and two females) donned the ISD for a 4 hr automated recording session, following excursion dives (up to 6hrs and 29 MSW below storage depth) from air saturation at 17 MSW. Doppler recordings for 32 excursion dives were collected. The recordings consisted of approximately 150 digital wave files. Each wave file contained 24 sec of recording for each min. A 1 - 4 Doppler Quality Score (DQS) was assigned to each wave file in 17 of the 32 records evaluated to date. A DQS of 1 indicates a poor flow signal and a score of 4 indicates an optimum signal. Only 23% of all wave files had DQSs considered adequate to detect low grade VGE (Spencer I-II). The distribution of DQS in 2,356 wave files is as follows: DQS 1-56%, DQS 2-21%, DQS 3-18% and DQS 4-5%. Six of the 17 records had false positive VGE (Spencer I-IV) detected in one or more wave files per dive record. The false positive VGE recordings are attributable to air entrainment associated with drinking (verified by control tests), and this observation is important as astronauts drink water during space walks. The current ISD design provides quality recordings only over a narrow range of chest anatomy.

  6. Fetal Echocardiography and Pulsed-wave Doppler Ultrasound in a Rabbit Model of Intrauterine Growth Restriction

    PubMed Central

    Hodges, Ryan; Endo, Masayuki; La Gerche, Andre; Eixarch, Elisenda; DeKoninck, Philip; Ferferieva, Vessilina; D'hooge, Jan; Wallace, Euan M.; Deprest, Jan

    2013-01-01

    Fetal intrauterine growth restriction (IUGR) results in abnormal cardiac function that is apparent antenatally due to advances in fetoplacental Doppler ultrasound and fetal echocardiography. Increasingly, these imaging modalities are being employed clinically to examine cardiac function and assess wellbeing in utero, thereby guiding timing of birth decisions. Here, we used a rabbit model of IUGR that allows analysis of cardiac function in a clinically relevant way. Using isoflurane induced anesthesia, IUGR is surgically created at gestational age day 25 by performing a laparotomy, exposing the bicornuate uterus and then ligating 40-50% of uteroplacental vessels supplying each gestational sac in a single uterine horn. The other horn in the rabbit bicornuate uterus serves as internal control fetuses. Then, after recovery at gestational age day 30 (full term), the same rabbit undergoes examination of fetal cardiac function. Anesthesia is induced with ketamine and xylazine intramuscularly, then maintained by a continuous intravenous infusion of ketamine and xylazine to minimize iatrogenic effects on fetal cardiac function. A repeat laparotomy is performed to expose each gestational sac and a microultrasound examination (VisualSonics VEVO 2100) of fetal cardiac function is performed. Placental insufficiency is evident by a raised pulsatility index or an absent or reversed end diastolic flow of the umbilical artery Doppler waveform. The ductus venosus and middle cerebral artery Doppler is then examined. Fetal echocardiography is performed by recording B mode, M mode and flow velocity waveforms in lateral and apical views. Offline calculations determine standard M-mode cardiac variables, tricuspid and mitral annular plane systolic excursion, speckle tracking and strain analysis, modified myocardial performance index and vascular flow velocity waveforms of interest. This small animal model of IUGR therefore affords examination of in utero cardiac function that is

  7. Two-dimensional ultrasound Doppler velocimeter for flow mapping of unsteady liquid metal flows.

    PubMed

    Franke, S; Lieske, H; Fischer, A; Büttner, L; Czarske, J; Räbiger, D; Eckert, S

    2013-03-01

    We present a novel pulsed-wave ultrasound Doppler system for fluid flow investigations being able to determine two-dimensional vector fields of flow velocities. Electromagnetically-driven liquid metal flows appear as an attractive application field for such a measurement system. Two linear ultrasound transducer arrays each equipped with 25 transducer elements are used to measure the flow field in a square plane of 67×67 mm(2). The application of advanced processing methods as a multi-beam operation, an interlaced echo signal acquisition and a segmental array technique enable high data acquisition rates and concurrently a high spatial resolution, which have not been obtained so far for flow measurements in liquid metals. The extended pulsing strategy and essential operation principles such as the multiplexing electronic concept will be presented within this paper. The capabilities of the measuring system make it suitable for investigations of non-transparent, turbulent flows. Here, we present measurements of liquid metal flows driven by a rotating magnetic field for demonstration purposes. The measuring setup realized here reveals details of the swirling fluid motion in a horizontal section of a cube. Frame acquisition rates up to 30 fps were achieved for a complete two-dimensional flow mapping.

  8. Assessment of arterial distension based on continuous wave Doppler ultrasound with an improved Hilbert-Huang processing.

    PubMed

    Zhang, Yufeng; Su, Nafeng; Li, Zhiyao; Gou, Zhengpin; Chen, Qiuying; Zhang, Yan

    2010-01-01

    A novel approach based on continuous wave (CW) Doppler ultrasound and the Hilbert-Huang transform with end-effect restraint by mirror extending is proposed to assess arterial distension. In the approach, bidirectional Doppler signals were first separated using the phasing-filter technique from the mixed quadrature Doppler signals, which were produced by bidirectional blood and vessel wall movements. Each separated unidirectional signal was decomposed into intrinsic mode functions (IMFs) using the empirical mode decomposition with end effect restraint by mirror extending algorithm, and then the relevant IMFs that contribute to the vessel wall components were identified. Finally, the displacement waveforms of the vessel wall were calculated by integrating its moving velocity waveforms, which were extracted from the bidirectional Hilbert spectrum estimated from the identified wall IMFs. This approach was applied to simulated and clinical Doppler signals from normal common carotid arteries (CCAs). In the simulation study, the estimated wall moving velocity and displacement waveforms were compared with the theoretical ones, respectively. The mean and standard deviation of the root-mean-square errors between the estimated and theoretical wall distension of the 30 realizations was 4.2 +/- 0.4 microm. In the clinical study, peak-to-peak distension was extracted in a subject and then averaged over 15 cardiac cycles, resulting in 603 +/- 22 microm. The mean and standard deviation of the CCA distension averaged over the experimental measurements of 12 healthy subjects gave the result of 620 +/- 154 microm. The clinical results were in agreement with those measured by using the multigate Doppler ultrasound and echo tracking systems. The results show that based on the CW Doppler ultrasound, the proposed approach is practical for extracting arterial wall peak-to-peak distension correctly and could be an alternative method for the vessel wall distension estimation.

  9. 'Son et lumière': a new combined optical and Doppler ultrasound approach to the detection of breast cancer.

    PubMed

    Watmough, D J; Moran, C; Watmough, J A

    1988-04-01

    X-ray mammography is the gold standard for diagnosis of lesions within the female breast. It is also recognized as the technique of choice for breast cancer screening in women over 50-years-old. Notwithstanding these important roles it has shortcomings in terms of limited sensitivity and specificity, especially in younger women. This paper describes the concept of a combined optical density and Doppler ultrasound method proposed initially as a supplement to mammography. A specially devised tissue compressor is also described. Results obtained using test phantoms and initial clinical studies are presented. Neovascularization at the advancing front of neoplastic lesions is believed to underlie detection of lesions by both telediaphanography and Doppler ultrasound.

  10. Color Doppler ultrasound and gamma imaging of intratumorally injected 500 nm iron-silica nanoshells.

    PubMed

    Liberman, Alexander; Wu, Zhe; Barback, Christopher V; Viveros, Robert; Blair, Sarah L; Ellies, Lesley G; Vera, David R; Mattrey, Robert F; Kummel, Andrew C; Trogler, William C

    2013-07-23

    Perfluoropentane gas filled iron-silica nanoshells have been developed as stationary ultrasound contrast agents for marking tumors to guide surgical resection. It is critical to establish their long-term imaging efficacy, as well as biodistribution. This work shows that 500 nm Fe-SiO2 nanoshells can be imaged by color Doppler ultrasound over the course of 10 days in Py8119 tumor bearing mice. The 500 nm nonbiodegradable SiO2 and biodegradable Fe-SiO2 nanoshells were functionalized with diethylenetriamine pentaacetic acid (DTPA) ligand and radiolabeled with (111)In(3+) for biodistribution studies in nu/nu mice. The majority of radioactivity was detected in the liver and kidneys following intravenous (IV) administration of nanoshells to healthy animals. By contrast, after nanoshells were injected intratumorally, most of the radioactivity remained at the injection site; however, some nanoshells escaped into circulation and were distributed similarly as those given intravenously. For intratumoral delivery of nanoshells and IV delivery to healthy animals, little difference was seen between the biodistribution of SiO2 and biodegradable Fe-SiO2 nanoshells. However, when nanoshells were administered IV to tumor bearing mice, a significant increase was observed in liver accumulation of SiO2 nanoshells relative to biodegradable Fe-SiO2 nanoshells. Both SiO2 and Fe-SiO2 nanoshells accumulate passively in proportion to tumor mass, during intravenous delivery of nanoshells. This is the first report of the biodistribution following intratumoral injection of any biodegradable silica particle, as well as the first report demonstrating the utility of DTPA-(111)In labeling for studying silica nanoparticle biodistributions.

  11. Improved determination of vascular blood-flow shear rate using Doppler ultrasound

    NASA Astrophysics Data System (ADS)

    Farison, James B.; Begeman, Garett A.; Salles-Cunha, Sergio X.; Beebe, Hugh G.

    1997-05-01

    Shear rate has been linked to endothelial and smooth muscle cell function, neointimal hyperplasia, poststenotic dilation and progression of atherosclerotic plaque. In vivo studies of shear rate have been limited in humans due to the lack of a truly accurate noninvasive method of measuring blood flow. In clinical vascular laboratories, the primary method of wall shear rate estimation is the scaled ratio between the center line systolic velocity and the local arterial radius. The present study compares this method with the shear rate calculated directly from data collected using a Doppler ultrasound scanner. Blood flow in the superficial femoral artery of 20 subjects was measured during three stages of distal resistance. Analysis and display programs were written for use with the MATLAB image processing software package. The experimental values of shear rate were calculated using the formal definition and then compared to the standard estimate. In all three states of distal resistance, the experimental values were significantly higher than the estimated values by a factor of approximately 1.57. These results led to the conclusion that the direct method of measuring shear rate is more precise and should replace the estimation model in the clinical laboratory.

  12. Clinical value of color doppler ultrasound in prenatal diagnosis of umbilical cord entry abnormity

    PubMed Central

    Sun, Jiandong; Wang, Li; Li, Yinghui

    2016-01-01

    Objective: To study the clinical value of prenatal diagnosis of umbilical cord entry abnormity (UCEA) by means of color Doppler ultrasound (CDUS). Methods: Clinical data of sixty-four cases with confirmed umbilical cord entry abnormity were reviewed and the specific UCEA conditions and the outcomes of perinatal infants were analyzed. Results: Detection rates of marginal umbilical cord entry abnormity and velamentous umbilical cord entry abnormity by means of CDUS at second trimester were 94.1% and 93.8% respecdtively much higher than 80.0% and 68.8% which were those of third trimester. Discrepancy had statistical significance (P<0.05). True positive rate of prenatal diagnosis of UCEA by means of CDUS was 85.9% (55/64), and false negative rate was 14.1% (9/64). Among sixty four patients with UCEA, seventeen patients (26.6%) underwent selective caesarean delivery; twenty-six patients (35.9%) underwent emergency caesarean delivery and twenty-four patients (37.5%) had normal delivery. Conclusion: Prenatal diagnosis of UCEA by means of CDUS is intuitive and accurate. It provides an evidence for determination of the best time to diagnose UCEA, and also offers a proper advice for pregnant women about delivery mode to ensure the fetus survival rate, which is clinically valuable. PMID:28083036

  13. Estimation of the viscoelastic properties of vessel walls using a computational model and Doppler ultrasound

    NASA Astrophysics Data System (ADS)

    Balocco, Simone; Basset, Olivier; Courbebaisse, Guy; Boni, Enrico; Frangi, Alejandro F.; Tortoli, Piero; Cachard, Christian

    2010-06-01

    Human arteries affected by atherosclerosis are characterized by altered wall viscoelastic properties. The possibility of noninvasively assessing arterial viscoelasticity in vivo would significantly contribute to the early diagnosis and prevention of this disease. This paper presents a noniterative technique to estimate the viscoelastic parameters of a vascular wall Zener model. The approach requires the simultaneous measurement of flow variations and wall displacements, which can be provided by suitable ultrasound Doppler instruments. Viscoelastic parameters are estimated by fitting the theoretical constitutive equations to the experimental measurements using an ARMA parameter approach. The accuracy and sensitivity of the proposed method are tested using reference data generated by numerical simulations of arterial pulsation in which the physiological conditions and the viscoelastic parameters of the model can be suitably varied. The estimated values quantitatively agree with the reference values, showing that the only parameter affected by changing the physiological conditions is viscosity, whose relative error was about 27% even when a poor signal-to-noise ratio is simulated. Finally, the feasibility of the method is illustrated through three measurements made at different flow regimes on a cylindrical vessel phantom, yielding a parameter mean estimation error of 25%.

  14. Estimation of the viscoelastic properties of vessel walls using a computational model and Doppler ultrasound.

    PubMed

    Balocco, Simone; Basset, Olivier; Courbebaisse, Guy; Boni, Enrico; Frangi, Alejandro F; Tortoli, Piero; Cachard, Christian

    2010-06-21

    Human arteries affected by atherosclerosis are characterized by altered wall viscoelastic properties. The possibility of noninvasively assessing arterial viscoelasticity in vivo would significantly contribute to the early diagnosis and prevention of this disease. This paper presents a noniterative technique to estimate the viscoelastic parameters of a vascular wall Zener model. The approach requires the simultaneous measurement of flow variations and wall displacements, which can be provided by suitable ultrasound Doppler instruments. Viscoelastic parameters are estimated by fitting the theoretical constitutive equations to the experimental measurements using an ARMA parameter approach. The accuracy and sensitivity of the proposed method are tested using reference data generated by numerical simulations of arterial pulsation in which the physiological conditions and the viscoelastic parameters of the model can be suitably varied. The estimated values quantitatively agree with the reference values, showing that the only parameter affected by changing the physiological conditions is viscosity, whose relative error was about 27% even when a poor signal-to-noise ratio is simulated. Finally, the feasibility of the method is illustrated through three measurements made at different flow regimes on a cylindrical vessel phantom, yielding a parameter mean estimation error of 25%.

  15. Doppler Frequency-Shift Compensated Photorefractive Interferometer for Ultrasound Detection on Objects in Motion

    NASA Astrophysics Data System (ADS)

    Campagne, B.; Blouin, A.; Néron, C.; Monchalin, J.-P.

    2003-03-01

    Two-wave mixing based interferometry has been demonstrated to be a powerful technique for non-contact, broadband and speckle insensitive measurements of the small surface displacements produced by ultrasonic waves propagating in an object. When the object is in rapid motion along the line-of-sight of the probing laser or when the laser beam is rapidly scanned on a wavy surface, the two-wave mixing photorefractive interferometer loses sensitivity to the point it could become useless. To circumvent the Doppler frequency-shift produced by this relative motion, we propose a dynamic compensation scheme. We report a particularly simple scheme to implement this concept by monitoring the low-frequency output signal of a balanced two-wave mixing demodulator whose output is proportional to the frequency difference between the pump and signal beams, and feeding this signal back to the acousto-optic shifter. With this new concept, the two-wave mixing interferometer can operate on objects in rapid motion while maintaining its sensitivity to low frequency ultrasound.

  16. Transcranial Doppler ultrasound and the etiology of neurologic decompression sickness during altitude decompression

    NASA Technical Reports Server (NTRS)

    Norfleet, W. T.; Powell, M. R.; Kumar, K. Vasantha; Waligora, J.

    1993-01-01

    The presence of gas bubbles in the arterial circulation can occur from iatrogenic mishaps, cardiopulmonary bypass devices, or following decompression, e.g., in deep-sea or SCUBA diving or in astronauts during extravehicular activities (EVA). We have examined the pathophysiology of neurological decompression sickness in human subjects who developed a large number of small gas bubbles in the right side of the heart as a result of hypobaric exposures. In one case, gas bubbles were detected in the middle cerebral artery (MCA) and the subject developed neurological symptoms; a 'resting' patent foramen ovalae (PFO) was found upon saline contrast echocardiography. A PFO was also detected in another individual who developed Spencer Grade 4 precordial Doppler ultrasound bubbles, but no evidence was seen of arterialization of bubbles upon insonation of either the MCA or common carotid artery. The reason for this difference in the behavior of intracardiac bubbles in these two individuals is not known. To date, we have not found evidence of right-to-left shunting of bubbles through pulmonary vasculature. The volume of gas bubbles present following decompression is examined and compared with the number arising from saline contrast injection. The estimates are comparable.

  17. Utility of transcranial Doppler ultrasound for the integrative assessment of cerebrovascular function.

    PubMed

    Willie, C K; Colino, F L; Bailey, D M; Tzeng, Y C; Binsted, G; Jones, L W; Haykowsky, M J; Bellapart, J; Ogoh, S; Smith, K J; Smirl, J D; Day, T A; Lucas, S J; Eller, L K; Ainslie, P N

    2011-03-30

    There is considerable utility in the use of transcranial Doppler ultrasound (TCD) to assess cerebrovascular function. The brain is unique in its high energy and oxygen demand but limited capacity for energy storage that necessitates an effective means of regional blood delivery. The relative low cost, ease-of-use, non-invasiveness, and excellent temporal resolution of TCD make it an ideal tool for the examination of cerebrovascular function in both research and clinical settings. TCD is an efficient tool to access blood velocities within the cerebral vessels, cerebral autoregulation, cerebrovascular reactivity to CO(2), and neurovascular coupling, in both physiological states and in pathological conditions such as stroke and head trauma. In this review, we provide: (1) an overview of TCD methodology with respect to other techniques; (2) a methodological synopsis of the cerebrovascular exam using TCD; (3) an overview of the physiological mechanisms involved in regulation of the cerebral blood flow; (4) the utility of TCD for assessment of cerebrovascular pathology; and (5) recommendations for the assessment of four critical and complimentary aspects of cerebrovascular function: intra-cranial blood flow velocity, cerebral autoregulation, cerebral reactivity, and neurovascular coupling. The integration of these regulatory mechanisms from an integrated systems perspective is discussed, and future research directions are explored.

  18. Effect of low level laser therapy on revascularization of free gingival graft using ultrasound Doppler flowmetry

    PubMed Central

    Arunachalam, Lalitha T.; Sudhakar, Uma; Janarthanam, Akila Sivaranjani; Das, Nimisha Mithra

    2014-01-01

    Low level laser therapy (LLLT) is widely used during the post-operative period to accelerate the healing process. It promotes beneficial biological action on neovascularization with anti-inflammatory and analgesic effects. Two systemically healthy patients with Miller's grade II recession on 33 and 41, respectively, were treated with free gingival graft. After surgery, second patient received LLLT using a 830 nm diode laser, with output power of 0.1 W on the first day half hour following surgery, on the third day, seventh day, and lastly on the ninth day. Both the patients were asked to assess the pain on second, fourth and tenth day using a Numerical Rating Scale and revascularization of the grafted area was assessed using a color Doppler ultrasound imaging on the fourth and the ninth day. Neovascularization was noted in both the patients but the second patient elicited marked increase in vascularity on the fourth as well as the tenth day and drastic reduction in pain on day four, with no change on the tenth day. The results showed that LLLT was an effective adjunctive treatment in promoting reevascularization and pain control during early healing of free gingival graft. PMID:25024560

  19. Pulsatility Produced by the Hemodialysis Roller Pump as Measured by Doppler Ultrasound.

    PubMed

    Fulker, David; Keshavarzi, Gholamreza; Simmons, Anne; Pugh, Debbie; Barber, Tracie

    2015-11-01

    Microbubbles have previously been detected in the hemodialysis extracorporeal circuit and can enter the blood vessel leading to potential complications. A potential source of these microbubbles is highly pulsatile flow resulting in cavitation. This study quantified the pulsatility produced by the roller pump throughout the extracorporeal circuit. A Sonosite S-series ultrasound probe (FUJIFILM Sonosite Inc., Tokyo, Japan) was used on a single patient during normal hemodialysis treatment. The Doppler waveform showed highly pulsatile flow throughout the circuit with the greatest pulse occurring after the pump itself. The velocity pulse after the pump ranged from 57.6 ± 1.74 cm/s to -72 ± 4.13 cm/s. Flow reversal occurred when contact between the forward roller and tubing ended. The amplitude of the pulse was reduced from 129.6 cm/s to 16.25 cm/s and 6.87 cm/s following the dialyzer and venous air trap. This resulted in almost nonpulsatile, continuous flow returning to the patient through the venous needle. These results indicate that the roller pump may be a source of microbubble formation from cavitation due to the highly pulsatile blood flow. The venous air trap was identified as the most effective mechanism in reducing the pulsatility. The inclusion of multiple rollers is also recommended to offer an effective solution in dampening the pulse produced by the pump.

  20. Doppler Velocity Estimation Based on Spectral Characteristics of M-Sequence-Modulated Signals in Ultrasonic Measurement for Moving Objects

    NASA Astrophysics Data System (ADS)

    Hirata, Shinnosuke; Hachiya, Hiroyuki

    2013-07-01

    Pulse compression using maximum-length sequence (M-sequence) can improve the signal-to-noise ratio (SNR) of the reflected echo and distance resolution in the pulse-echo method. In the case of a moving object, however, the echo is modulated due to the Doppler effect. The Doppler-shifted M-sequence-modulated signal cannot be correlated with the reference signal, which corresponds to the transmitted M-sequence-modulated signal. Therefore, Doppler velocity estimation before the correlation and cross correlation of the received signal with Doppler-shifted reference signals has been proposed. In this paper, the proposed Doppler velocity estimation based on spectral characteristics of cyclic M-sequence-modulated signals is described. Then, the Doppler velocity estimation is evaluated based on computer simulations. The Doppler velocity can be estimated from the Fourier-transformed spectral density of cycles of the M-sequence-modulated signal with high resolution even in noisy environments. According to the evaluation, furthermore, the cycle number and the number of carrier waves in 1 digit of the M-sequence-modulated signal should be decreased to improve the resolution and accuracy when the length of the transmitted signal is determined.

  1. Real-time system for robust spectral parameter estimation in Doppler signal analysis.

    PubMed

    Di Giuliomaria, C; Capponi, M; D'Alessio, T; Sacco, R; Zanette, E

    1990-01-01

    In assessing the level of stenosis in extracranial Doppler analysis, spectral analysis has until now been used qualitatively, for the most part. Owing to the many variables affecting the measurements (mainly noise level and instrument setting made subjectively by the operator), the reliability of the inferences on the degree of stenosis is not clearly definable. Under such conditions the need arises for algorithms and systems that can estimate spectral parameters with a higher degree of accuracy, to verify whether reliable inferences can indeed by made or if this technique is only a qualitative one. In the paper a real-time spectral analysis system is described. The system relies on a new spectral estimation algorithm which gives estimates with good robustness with respect to noise. Moreover, a clear measurement procedure which eliminates the many subjective factors affecting the estimates has also been proposed and used. The system has been evaluated with simulated signals and in clinical trials and has shown better performance than the commonly used commercial analysers.

  2. Ultrasound resistive index, power Doppler, and clinical parameters in established rheumatoid arthritis.

    PubMed

    Bisi, Melissa Cláudia; do Prado, Aline Defaveri; Piovesan, Deise Marcela; Bredemeier, Markus; da Silveira, Inês Guimarães; de Mendonça, José Alexandre; Staub, Henrique Luiz

    2017-04-01

    Ultrasonography (US) is a useful tool for the evaluation of sinovial vascularization and proliferation in rheumatoid arthritis (RA). Accordingly, resistive index (RI) on spectral Doppler (sD) US provides a quantitative analysis of vascular inflammation, but its utility in the evaluation of RA activity has not been established. Our objective was to determine the association of RI with other US parameters of synovitis and with clinical disease activity in established RA. Patients with positive power Doppler (pD) were included in a prospective cross-sectional study. Disease activity and disability were evaluated using the Disease Activity Score in 28-joints (DAS28) and Health Assessment Questionnaire (HAQ), respectively. Gray scale (GS) synovitis, pD, and sD analyses were performed by one of two examiners in wrists and the second and third metacarpophalangeal and proximal interphalangeal joints. The 10-joint GS and 10-joint pD scores and mean RI were then calculated. Weighted kappa (WK) values were employed to assess interobserver reability, and correlations were tested using the Spearman coefficient. Ninety-five RA patients (median duration of disease of 7 years and mean DAS28 of 4.32 ± 1.66) were included. WK values in real-time US were 0.77 for synovitis, 0.87 for pD, and 0.68 for RI. There were no significant correlations of RI with 10-joint GS, 10-joint pD, DAS28, joint counts, or HAQ (P > 0.10 for all tests). Patients in remission had a mean RI similar to those with high disease activity (0.62 ± 0.10, n = 15 versus 0.63 ± 0.13, n = 34, respectively). The addition of the RI score did not seem to improve US performance in patients with established RA.

  3. Anticoagulant therapy for venous thromboembolism detected by Doppler ultrasound in patients with metastatic colorectal cancer receiving bevacizumab

    PubMed Central

    Suenaga, Mitsukuni; Mizunuma, Nobuyuki; Shinozaki, Eiji; Matsusaka, Satoshi; Ozaka, Masato; Ogura, Mariko; Chin, Keisho; Yamaguchi, Toshiharu

    2015-01-01

    Background Doppler ultrasound imaging is useful for management of venous thromboembolism associated with a subclavicular implantable central venous access system in patients receiving bevacizumab (Bev). We investigated the efficacy and safety of our anticoagulant regimen based on Doppler findings. Methods Patients aged ≤75 years with metastatic colorectal cancer, no history of thromboembolism, and no prior use of Bev received chemotherapy plus Bev. Doppler ultrasound imaging of the deep venous system to detect thrombosis was performed after the first course of Bev and repeated after the third course in patients with asymptomatic thrombosis. Indications for anticoagulant therapy in patients with asymptomatic thrombosis were as follows: enlarging thrombus (E), thrombus >40 mm in diameter (S), thrombus involving the superior vena cava (C), and decreased blood flow (V). Results Among 79 patients enrolled in this study, asymptomatic thrombosis was detected in 56 patients (70.9%) by Doppler ultrasound imaging after the first course of Bev and there was no thrombus in 23 patients (29.1%). Of these 56 patients, 11 (19.6%) received anticoagulant therapy with warfarin, including eight after the first course and three after follow-up imaging. S + V was observed in four of 11 patients (36.4%), as well as V in two (18.2%), S + V + C in one (9.1%), E + S + V in one (9.1%), E + C in one (9.1%), E in one (9.1%), and C in one (9.1%). All patients resumed chemotherapy, including seven who resumed Bev. Improvement or stabilization of thrombi was achieved in ten patients (90.9%). Only one patient had symptomatic thromboembolism. Mild bleeding due to anticoagulant therapy occurred in six patients (54.5%), but there were no treatment-related severe adverse events or deaths. Severe thromboembolism was not observed in the other 68 patients. Conclusion Our anticoagulant protocol for asymptomatic thrombosis detected by Doppler ultrasound imaging was effective at preventing severe

  4. Color Doppler Ultrasound in Diagnosis and Assessment of Carotid Body Tumors: Comparison with Computed Tomography Angiography.

    PubMed

    Jin, Zhan-Qiang; He, Wen; Wu, Dong-Fang; Lin, Mei-Ying; Jiang, Hua-Tang

    2016-09-01

    A carotid body tumor (CBT) is a rare, non-chromaffin paraganglioma, and its diagnosis mainly depends on imaging modalities. The aim of this study was to investigate the ability of color Doppler ultrasound (CDU) in the diagnosis and assessment of CBT based on computed tomography (CT). We retrospectively reviewed the CDU and CT features of 49 consecutive CBTs and 23 schwannomas from 67 patients and compared these findings with surgical resection specimens. The mean size of CBT lesions on ultrasound scans and CT angiography (CTA) was 3.24 cm ± 0.82 cm (range, 1.6-5.2 cm) and 3.84 cm ± 1.08 cm (range, 1.8-6.8 cm), respectively, which had statistically significant difference (t = 9.815, p = 0.000). The vascularity of CBT lesions was richer than that of schwannoma lesions (p < 0.05). Intra-lesional vascularities feeding CBT mostly arose from the external carotid artery and had spectrum characteristics including low velocity and resistance. Peak systolic velocity (PSV) and resistance index (RI) of the vasa vasorum were 39.8 cm/s ± 19.8 cm/s and 0.54 ± 0.06, respectively. There was the correlation between CTA and CDU in identifying Shamblin type I CBT lesions, while CTA technique was superior for CDU, identifying Shamblin type II and III CBT lesions. Accuracy, specificity and sensitivity of CDU in diagnosing CBTs were 87.5% (63 of 72), 82.6% (19 of 23) and 89.8% (44 of 49), respectively. Both accuracy and sensitivity of CTA in diagnosing CBTs were 100%. CDU can be useful for assessment of Shamblin's type and intra-lesional blood flow of CBTs before its metastases, while CT imaging can reveal the relationship between lesions and adjacent arteries, as well as the involvement of the skull base. CDU combined with CT imaging can be used as an optimal detection modality for the assessment and management of CBT.

  5. Dual-frequency radar Doppler spectral retrieval of rain drop size distributions and entangled dynamics variables

    NASA Astrophysics Data System (ADS)

    Tridon, F.; Battaglia, A.

    2015-06-01

    A novel technique based on Ka-W band dual-wavelength Doppler spectra has been developed for the simultaneous retrieval of binned rain drop size distributions (DSD) and air state parameters like vertical wind and air broadening caused by turbulence and wind shear. The rationale underpinning the method consists in exploiting the peculiar features observed in Doppler spectra caused by the wavelength dependence of scattering and absorption properties. A notional study based on a large data set of DSDs measured by a two-dimensional video disdrometer demonstrates that the retrieval performs best for small/moderate air broadening spectral width and when mean volume diameters exceed at least 1 mm. The retrieval is also limited to ranges below cloud base and where the signal-to-noise ratio of both radars exceed 10 dB, which rules out regions affected by strong attenuation. Broadly speaking, it is applicable to rain rates comprised between roughly 1 and 30 mm h-1. Preliminary retrieval for observations at the Atmospheric Radiation Measurement Southern Great Plains site shows very good agreement with independent reflectivity measurements from a 0.915 GHz wind profiler. The proposed methodology shows great potential in linking microphysics to dynamics in rainfall studies.

  6. Quantitative Measurement of Blood Flow Dynamics in Embryonic Vasculature Using Spectral Doppler Velocimetry

    PubMed Central

    Davis, Anjul; Izatt, Joseph; Rothenberg, Florence

    2010-01-01

    The biophysical effects of blood flow are known to influence the structure and function of adult cardiovascular systems. Similar effects on the maturation of the cardiovascular system have been difficult to directly and non-invasively measure due to the small size of the embryo. Optical coherence tomography (OCT) has been shown to provide high spatial and temporal structural imaging of the early embryonic chicken heart. We have developed an extension of Doppler OCT, called spectral Doppler velocimetry (SDV), that will enable direct, non-invasive quantification of blood flow and shear rate from the early embryonic cardiovascular system. Using this technique, we calculated volumetric flow rate and shear rate from chicken embryo vitelline vessels. We present blood flow dynamics and spatial velocity profiles from three different vessels in the embryo as well as measurements from the outflow tract of the embryonic heart tube. This technology can potentially provide spatial mapping of blood flow and shear rate in embryonic cardiovascular structures, producing quantitative measurements that can be correlated with gene expression and normal and abnormal morphology. PMID:19248163

  7. Comparison of time-frequency distribution techniques for analysis of simulated Doppler ultrasound signals of the femoral artery.

    PubMed

    Guo, Z; Durand, L G; Lee, H C

    1994-04-01

    The time-frequency distribution of the Doppler ultrasound blood flow signal is normally computed by using the short-time Fourier transform or autoregressive modeling. These two techniques require stationarity of the signal during a finite interval. This requirement imposes some limitations on the distribution estimate. In the present study, three new techniques for nonstationary signal analysis (the Choi-Williams distribution, a reduced interference distribution, and the Bessel distribution) were tested to determine their advantages and limitations for analysis of the Doppler blood flow signal of the femoral artery. For the purpose of comparison, a model stimulating the quadrature Doppler signal was developed, and the parameters of each technique were optimized based on the theoretical distribution. Distributions computed using these new techniques were assessed and compared with those computed using the short-time Fourier transform and autoregressive modeling. Three indexes, the correlation coefficient, the integrated squared error, and the normalized root-mean-squared error of the mean frequency waveform, were used to evaluate the performance of each technique. The results showed that the Bessel distribution performed the best, but the Choi-Williams distribution and autoregressive modeling are also techniques which can generate good time-frequency distributions of Doppler signals.

  8. Image analysis of placental issues using three-dimensional ultrasound and color power Doppler based on Support Vector Machine

    NASA Astrophysics Data System (ADS)

    Wang, Qi; Xu, Diyun; Liu, Jianguo

    2009-10-01

    With the development of medical science, three-dimensional ultrasound and color power Doppler tomography shooting placenta is widely used. To determine whether the fetus's development is abnormal or not is mainly through the analysis of the capillary's distribution of the obtained images which are shot by the Doppler scanner. In this classification process, we will adopt Support Vector Machine classifier. SVM achieves substantial improvements over the statistical learning methods and behaves robustly over a variety of different learning tasks. Furthermore, it is fully automatic, eliminating the need for manual parameter tuning and can solve the small sample problem wonderfully well. So SVM classifier is valid and reliable in the identification of placentas and is more accurate with the lower error rate.

  9. Automated assessment of joint synovitis activity from medical ultrasound and power doppler examinations using image processing and machine learning methods

    PubMed Central

    Ziębiński, Adam

    2016-01-01

    Objectives Rheumatoid arthritis is the most common rheumatic disease with arthritis, and causes substantial functional disability in approximately 50% patients after 10 years. Accurate measurement of the disease activity is crucial to provide an adequate treatment and care to the patients. The aim of this study is focused on a computer aided diagnostic system that supports an assessment of synovitis severity. Material and methods This paper focus on a computer aided diagnostic system that was developed within joint Polish–Norwegian research project related to the automated assessment of the severity of synovitis. Semiquantitative ultrasound with power Doppler is a reliable and widely used method of assessing synovitis. Synovitis is estimated by ultrasound examiner using the scoring system graded from 0 to 3. Activity score is estimated on the basis of the examiner’s experience or standardized ultrasound atlases. The method needs trained medical personnel and the result can be affected by a human error. Results The porotype of a computer-aided diagnostic system and algorithms essential for an analysis of ultrasonic images of finger joints are main scientific output of the MEDUSA project. Medusa Evaluation System prototype uses bone, skin, joint and synovitis area detectors for mutual structural model based evaluation of synovitis. Finally, several algorithms that support the semi-automatic or automatic detection of the bone region were prepared as well as a system that uses the statistical data processing approach in order to automatically localize the regions of interest. Conclusions Semiquantitative ultrasound with power Doppler is a reliable and widely used method of assessing synovitis. Activity score is estimated on the basis of the examiner’s experience and the result can be affected by a human error. In this paper we presented the MEDUSA project which is focused on a computer aided diagnostic system that supports an assessment of synovitis severity

  10. Colour Doppler ultrasound hemodynamic characteristics of patients with priapism before and after therapeutic interventions.

    PubMed

    Chiou, Rei K; Aggarwal, Himanshu; Chiou, Christopher R; Broughton, Fleur; Liu, Susan

    2009-08-01

    BACKGROUND: Information in the literature on the hemodynamic characteristics of priapism, especially after therapeutic intervention, is very limited. We analyzed our colour Doppler ultrasound (CDU) studies performed for patients with various durations of priapism before and after therapeutic intervention. METHODS: We reviewed 52 CDU studies for 24 patients with priapism before and after treatment for the period 1997-2007. The duration of priapism ranged from 4 hours to 8 days. We performed 17 CDU studies in 8 patients who presented with a duration of priapism of 7 hours or less, 9 studies in 4 patients who presented with duration of priapism of more than 20 hours, 23 studies in 11 patients referred to us after they had failed prior therapeutic intervention at other institutions and 3 studies in 1 patient with priapism related to perineal trauma. RESULTS: Among the 8 patients who presented with a duration of priapism of 7 hours or less, CDU studies on presentation showed detectible cavernosal arterial flow in all except 1 study. Among the 4 patients who presented with a duration of more than 20 hours, the studies showed no detectible cavernosal arterial blood flow. We repeated CDU studies after therapeutic intervention, and they showed restoration of cavernosal arterial flow with relief of veno-occlusive status. Among the 11 patients in whom prior treatments failed before they were referred to us, CDU studies performed on presentation showed no detectible cavernosal arterial flow in 10 of the 11 patients. We performed 12 CDU studies in 8 patients after placing a penile cavernosa-dorsal vein (CD) shunt. We observed the presence of blood flow in the CD shunt, indicating its patency in all 8 patients. Some patients showed high cavernosal arterial flow (peak systolic velocity [PSV] up to 27.6 cm/s) after surgery. These patients appeared to have residual priapism of primarily arteriogenic status that improved after observation. CONCLUSION: After therapeutic intervention

  11. Power Doppler ultrasound phenotyping of expanding versus collapsed popliteal lymph nodes in murine inflammatory arthritis.

    PubMed

    Bouta, Echoe M; Ju, Yawen; Rahimi, Homaira; de Mesy-Bentley, Karen L; Wood, Ronald W; Xing, Lianping; Schwarz, Edward M

    2013-01-01

    Rheumatoid arthritis is a chronic inflammatory disease manifested by episodic flares in affected joints that are challenging to predict and treat. Longitudinal contrast enhanced-MRI (CE-MRI) of inflammatory arthritis in tumor necrosis factor-transgenic (TNF-Tg) mice has demonstrated that popliteal lymph nodes (PLN) increase in volume and contrast enhancement during the pre-arthritic "expanding" phase of the disease, and then suddenly "collapse" during knee flare. Given the potential of this biomarker of arthritic flare, we aimed to develop a more cost-effective means of phenotyping PLN using ultrasound (US) imaging. Initially we attempted to recapitulate CE-MRI of PLN with subcutaneous footpad injection of US microbubbles (DEFINITY®). While this approach allowed for phenotyping via quantification of lymphatic sinuses in PLN, which showed a dramatic decrease in collapsed PLN versus expanding or wild-type (WT) PLN, electron microscopy demonstrated that DEFINITY® injection also resulted in destruction of the lymphatic vessels afferent to the PLN. In contrast, Power Doppler (PD) US is innocuous to and efficiently quantifies blood flow within PLN of WT and TNF-Tg mice. PD-US demonstrated that expanding PLN have a significantly higher normalized PD volume (NPDV) versus collapsed PLN (0.553 ± 0.007 vs. 0.008 ± 0.003; p<0.05). Moreover, we define the upper (>0.030) and lower (<0.016) quartile NPDVs in this cohort of mice, which serve as conservative thresholds to phenotype PLN as expanding and collapsed, respectively. Interestingly, of the 12 PLN phenotyped by the two methods, there was disagreement in 4 cases in which they were determined to be expanding by CE-MRI and collapsed by PD-US. Since the adjacent knee had evidence of synovitis in all 4 cases, we concluded that the PD-US phenotyping was correct, and that this approach is currently the safest and most cost-effective in vivo approach to phenotype murine PLN as a biomarker of arthritic flare.

  12. Doppler ultrasound surveillance in deep tunneling compressed-air work with Trimix breathing: bounce dive technique compared to saturation-excursion technique.

    PubMed

    Vellinga, T P van Rees; Sterk, W; de Boer, A G E M; van der Beek, A J; Verhoeven, A C; van Dijk, F J H

    2008-01-01

    The Western Scheldt Tunneling Project in The Netherlands provided a unique opportunity to evaluate two deep-diving techniques with Doppler ultrasound surveillance. Divers used the bounce diving techniques for repair and maintenance of the TBM. The tunnel boring machine jammed at its deepest depth. As a result the work time was not sufficient. The saturation diving technique was developed and permitted longer work time at great depth. Thirty-one divers were involved in this project. Twenty-three divers were examined using Doppler ultrasound. Data analysis addressed 52 exposures to Trimix at 4.6-4.8 bar gauge using the bounce technique and 354 exposures to Trimix at 4.0-6.9 bar gauge on saturation excursions. No decompression incidents occurred with either technique during the described phase of the project. Doppler ultrasound revealed that the bubble loads assessed in both techniques were generally low. We find out, that despite longer working hours, shorter decompression times and larger physical workloads, the saturation-excursion technique was associated with significant lower bubble grades than in the bounce technique using Doppler Ultrasound. We conclude that the saturation-excursion technique with Trimix is a good option for deep and long exposures in caisson work. The Doppler technique proved valuable, and it should be incorporated in future compressed-air work.

  13. Focal bowel wall changes detected with colour Doppler ultrasound: diagnostic value in acute non-diverticular diseases of the colon.

    PubMed

    Danse, E M; Jamart, J; Hoang, P; Laterre, P F; Kartheuser, A; Van Beers, B E

    2004-11-01

    We performed a study to determine if colour Doppler findings may help to identify the cause of wall thickening in acute non-diverticular diseases of the colon. The study group included 66 patients admitted to the emergency department with a final diagnosis of infectious colitis (n=23), inflammatory colitis (n=10), ischaemic colitis (n=23) and malignant tumours (n=10). The following ultrasound features were assessed: maximal wall thickness, wall stratification, arterial flow in the colonic wall and arteriolar resistive index. Higher values of wall thickness were observed in malignant tumour (18.2+/-6.2 mm, p<0.001). Moderately thickened wall (6.6+/-1.3 mm, p< or =0.06), preserved stratification (90% versus 46% in the remainder of the study population) and lower resistive index (0.51+/-0.10, p< or =0.05) were significantly related to inflammatory colitis. Absence of arterial flow was more frequently observed in ischaemia (43% versus 12% in the remainder of the study population). In conclusion, despite some overlap, both ultrasound and colour Doppler features are helpful in the differential diagnosis of colonic thickening related to non-diverticular colonic lesions.

  14. Accuracy of velocity and shear rate measurements using pulsed Doppler ultrasound: a comparison of signal analysis techniques.

    PubMed

    Markou, C P; Ku, D N

    1991-01-01

    An experimental investigation was instituted to evaluate the performance of Doppler ultrasound signal processing techniques for measuring fluid velocity under well-defined flow conditions using a 10-MHz multigated pulsed ultrasound instrument. Conditions of fully developed flow in a rigid, circular tube were varied over a Reynolds number range between 500 and 8000. The velocity across the tube was determined using analog and digital zero crossing detectors and three digital spectrum estimators. Determination of the Doppler frequency from analog or digital zero crossing detectors gave accurate velocity values for laminar and moderately turbulent flow away from the wall (0.969 less than or equal to r less than or equal to 0.986). Three digital spectrum estimators, Fast Fourier Transform, Burg autoregressive method, and minimum variance method, were slightly more accurate than the zero crossing detector (0.984 less than or equal to r less than or equal to 0.994), especially at points close to the walls and with higher levels of turbulence. Steep velocity gradients and transit-time-effects from high velocities produced significantly larger errors in velocity measurement. Wall shear rate estimates were most precise when calculated using the position of the wall and two velocity points. The calculated wall shears were within 20%-30% of theoretically predicted values.

  15. Settings and artefacts relevant in colour/power Doppler ultrasound in rheumatology.

    PubMed

    Torp-Pedersen, S T; Terslev, L

    2008-02-01

    The paper explains the most important parameters for the use of colour and power Doppler in rheumatology. Recommendations for machine settings are given. The commonly encountered artefacts and their importance for image interpretation are explained.

  16. Parabolic BM-scan technique for full range Doppler spectral domain optical coherence tomography.

    PubMed

    Jaillon, Franck; Makita, Shuichi; Yabusaki, Masaki; Yasuno, Yoshiaki

    2010-01-18

    A full range spectral domain optical coherence tomography (SD-OCT) technique that relies on the linear phase modulation of one of the interferometer arms has been widely utilized. Although this method is useful, the mirror image elimination is not perfect for samples in which regions with high axial motion exist. In this paper, we introduce a new modulation pattern to overcome this mirror image elimination failure. This new modulation is a parabolic phase modulation in the transverse scanning direction, and is applied to the SD-OCT reference beam by an electro-optic modulator. Flow phantom and in vivo experiments demonstrate that for moving structures with large velocities, this parabolic phase modulation technique presents better mirror image elimination than a standard linear phase modulation method. A direct consequence of this enhanced mirror image removal is an improved velocity range obtained with phase-resolved Doppler imaging. Consequently, applying the proposed technique in retinal blood flow measurements may be useful for ophthalmologic diagnosis.

  17. Applications of spectral analysis and filter design in laser frequency locking for Na Doppler lidars

    NASA Astrophysics Data System (ADS)

    Smith, John A.; Chu, Xinzhao; Huang, Wentao; Tan, Bo

    2009-10-01

    A dye ring laser is stabilized to a D2a Doppler-free feature of sodium vapor using a LabVIEW®-based, phase-sensitive servo. Locking precision and stability, at better than +/-1 MHz, are suitable for Na lidar applications. This performance was achieved with improved digital filtering and new approaches to the problem. The inverse (type II) Chebyshev discrete filter employed demonstrates superior filtering and computational efficiency plus improved flexibility. New approaches include the determination of optimum modulation frequency, laser-tuning sensitivity, and bandwidth requirements via spectral analyses of the noise spectrum, derivative scan, and modulated spectrum. This practice guides a user in selecting the system operation parameters and negotiating the trade-offs involved when expanding the filter's passband. Allan deviation plots provide a quantitative description of the short- and long-term frequency excursions. A comparison of Allan deviation plots before and after locking shows a substantial improvement in stability throughout time scales from 0.10 to 10 s.

  18. Why Current Doppler Ultrasound Methodology Is Inaccurate in Assessing Cerebral Venous Return: The Alternative of the Ultrasonic Jugular Venous Pulse

    PubMed Central

    2016-01-01

    Assessment of cerebral venous return is growing interest for potential application in clinical practice. Doppler ultrasound (DUS) was used as a screening tool. However, three meta-analyses of qualitative DUS protocol demonstrate a big heterogeneity among studies. In an attempt to improve accuracy, several authors alternatively measured the flow rate, based on the product of the time average velocity with the cross-sectional area (CSA). However, also the quantification protocols lacked of the necessary accuracy. The reasons are as follows: (a) automatic measurement of the CSA assimilates the jugular to a circle, while it is elliptical; (b) the use of just a single CSA value in a pulsatile vessel is inaccurate; (c) time average velocity assessment can be applied only in laminar flow. Finally, the tutorial describes alternative ultrasound calculation of flow based on the Womersley method, which takes into account the variation of the jugular CSA overtime. In the near future, it will be possible to synchronize the electrocardiogram with the brain inflow (carotid distension wave) and with the outflow (jugular venous pulse) in order to nicely have a noninvasive ultrasound picture of the brain-heart axis. US jugular venous pulse may have potential use in neurovascular, neurocognitive, neurosensorial, and neurodegenerative disorders. PMID:27006525

  19. Assessment of the Effects of Low-Level Laser Therapy on the Thyroid Vascularization of Patients with Autoimmune Hypothyroidism by Color Doppler Ultrasound

    PubMed Central

    Höfling, Danilo Bianchini; Chavantes, Maria Cristina; Juliano, Adriana G.; Cerri, Giovanni G.; Knobel, Meyer; Yoshimura, Elisabeth M.; Chammas, Maria Cristina

    2012-01-01

    Background. Chronic autoimmune thyroiditis (CAT) frequently alters thyroid vascularization, likely as a result of the autoimmune process. Objective. To evaluate the effects of low-level laser therapy (LLLT) on the thyroid vascularization of patients with hypothyroidism induced by CAT using color Doppler ultrasound parameters. Methods. In this randomized clinical trial, 43 patients who underwent levothyroxine replacement for CAT-induced hypothyroidism were randomly assigned to receive either 10 sessions of LLLT (L group, n = 23) or 10 sessions of a placebo treatment (P group, n = 20). Color Doppler ultrasounds were performed before and 30 days after interventions. To verify the vascularity of the thyroid parenchyma, power Doppler was performed. The systolic peak velocity (SPV) and resistance index (RI) in the superior (STA) and inferior thyroid arteries (ITAs) were measured by pulsed Doppler. Results. The frequency of normal vascularization of the thyroid lobes observed in the postintervention power Doppler examination was significantly higher in the L than in the P group (P = 0.023). The pulsed Doppler examination revealed an increase in the SPV of the ITA in the L group compared with the P group (P = 0.016). No significant differences in the SPV of the STA and in the RI were found between the groups. Conclusion. These results suggest that LLLT can ameliorate thyroid parenchyma vascularization and increase the SPV of the ITA of patients with hypothyroidism caused by CAT. PMID:23316383

  20. Listening to speech recruits specific tongue motor synergies as revealed by transcranial magnetic stimulation and tissue-Doppler ultrasound imaging.

    PubMed

    D'Ausilio, A; Maffongelli, L; Bartoli, E; Campanella, M; Ferrari, E; Berry, J; Fadiga, L

    2014-01-01

    The activation of listener's motor system during speech processing was first demonstrated by the enhancement of electromyographic tongue potentials as evoked by single-pulse transcranial magnetic stimulation (TMS) over tongue motor cortex. This technique is, however, technically challenging and enables only a rather coarse measurement of this motor mirroring. Here, we applied TMS to listeners' tongue motor area in association with ultrasound tissue Doppler imaging to describe fine-grained tongue kinematic synergies evoked by passive listening to speech. Subjects listened to syllables requiring different patterns of dorso-ventral and antero-posterior movements (/ki/, /ko/, /ti/, /to/). Results show that passive listening to speech sounds evokes a pattern of motor synergies mirroring those occurring during speech production. Moreover, mirror motor synergies were more evident in those subjects showing good performances in discriminating speech in noise demonstrating a role of the speech-related mirror system in feed-forward processing the speaker's ongoing motor plan.

  1. Spectral analysis of laser Doppler skin blood flow oscillations in human essential arterial hypertension.

    PubMed

    Rossi, Marco; Carpi, Angelo; Di Maria, Cinzia; Galetta, Fabio; Santoro, Gino

    2006-01-01

    The aim of this study was to investigate whether human essential arterial hypertension (EHT) is associated with modification of the skin blood flowmotion (SBF), which could be a sign of skin microcirculatory impairment. Forearm skin perfusion was measured by laser Doppler flowmetry (LDF) in conventional perfusion units (PU) before and after ischemia in 20 middle-age newly diagnosed EHT untreated patients, in 20 middle-age long standing EHT treated patients and in 30 age and sex matched healthy normotensive subjects (NS). Power spectral density (PSD) of SBF total spectrum (0.009-1.6 Hz), as well of five different frequency intervals (FI), each of them related to endothelial (0.009-0.02 Hz), sympathetic (0.02-0.06 Hz), myogenic (0.06-0.2 Hz), respiratory (0.2-0.6) or cardiac (0.6-1.6) activity, was also measured in PU(2)/Hz before and after ishemia, using Fourier analysis of LDF signal. The three studied groups did not differ in basal and post-ischemic skin perfusion or in basal SBF parameters considered. However, while a significant post-ischemic increase in PSD of total spectrum SBF (P < 0.001) and of its different FI, with the only exception of respiratory FI, was observed in NS, a significsnt post-ischemic increase in PSD was observed only for total spectrum (P < 0.01) and for endothelial FI (P < 0.001) in newly diagnosed EHT patients and only for myogenic FI (P < 0.05) in long standing EHT patients. These findings suggest that the mechanisms which mediate the post-ischemic increment of SBF are perturbed earlier in human EHT than the mechanisms which mediate the skin post-ischemic hyperaemia. The same findings also suggest that the impairment of the endothelial mechanism involved in SBF control occurs by the time in the course of EHT.

  2. Sizing of Emboli in Flowing Blood Using Pulse Doppler Ultrasound and the Embolus-To Power Ratio.

    NASA Astrophysics Data System (ADS)

    Moehring, Mark Alan

    The embolus to blood ratio (EBR) theoretical model describing pulse Doppler ultrasound observations of emboli in flowing blood is summarized. The EBR model uses the backscattered signal power from blood in the Doppler sample volume as a reference from which to assess embolus size and composition. This EBR is independent of attenuation and reflection loss in intervening tissues between probe and bloodflow. An in vitro investigation is presented that tests the validity of the EBR model. The experimental apparatus includes a novel phantom for Doppler observation of circulating emboli and a Doppler system which uses 1.6 and 2.4 MHz concurrently for interrogation of an embolus. The phantom contains a tubeless flow conduit inside a polyacrylamide gel and a blood-mimicking fluid flowing in the conduit. Time series Doppler shift data which are gathered while polystyrene microsphere "emboli" transit the sample volume are post -processed to calculate the EBR on each embolic signature. EBR measurements from microspheres of three different diameters are summarized and shown to contain pronounced and systematic variability. The hypothesis is presented that this variability is due to a small speed of sound mismatch between the gel and the blood-mimicking fluid, a phenomenon anticipated in vivo. This speed of sound mismatch results in beam refraction and a non-uniformly insonated sample volume (thereby causing variability in embolus signatures). A three dimensional theoretical study is presented that models beam refraction resulting from speed of sound mismatch between the blood mimicking fluid and the surrounding gel. A Monte Carlo study of the EBR behavior in the presence of beam refraction is performed and yields similar results to the data obtained in vitro. This study is evidence that the experimental signal variability is due to speed of sound mismatch between blood-mimicking fluid and gel. A method of extracting embolus size from the dual frequency EBR data based on the

  3. [Doppler ultrasound assisted hemorrhoid artery ligation. A new therapy in symptomatic hemorrhoids].

    PubMed

    Arnold, S; Antonietti, E; Rollinger, G; Scheyer, M

    2002-03-01

    In 1995, Morinaga et al. (Japan) reported on a new technique in the treatment of hemorrhoids. We report the results of our first 105 patients thus treated. By a specially designed proctoscope coupled with a Doppler transducer, the hemorrhoidal arteries are looked for and ligated. All stages of hemorrhoid were treated. This method is painless, successful, and has a low rate of complications. It is for outpatients and is an alternative to all other methods in the treatment of hemorrhoids.

  4. Understanding quantification of microvascularity with high-frequency power Doppler ultrasound

    NASA Astrophysics Data System (ADS)

    Pinter, Stephen Z.; Lacefield, James C.

    2009-02-01

    High-frequency power Doppler imaging of angiogenesis can be challenging given the presence of small blood vessels and slow flow velocities. In the presence of substantial Doppler artifacts such as false-positive color pixels or undetected vessels, color pixel density (CPD) and related vascularity metrics do not provide accurate estimates of vascular volume fraction. As a step towards improved microvascular quantification, flow-phantom experiments were performed to establish relationships between CPD and wall filter cut-off velocity for various combinations of vessel size (160, 200, 250, 300, and 360 μm), flow velocity (4, 3, 2, 1, and 0.5 mm/s), and transducer frequency (30 and 40 MHz). Three distinct regions were observed in plots of CPD versus wall filter cut-off velocity: overestimation of CPD at low cut-offs, underestimation of CPD at high cut-offs, and a plateau at intermediate cut-offs. The CPD at the plateau closely matched the phantom's actual vascular volume fraction. The length of the plateau corresponded with the flow-detection performance of the Doppler system, which was assessed using receiver operating characteristic analysis. Color pixel density versus wall filter cut-off curves from analogous in vivo experiments exhibited the same shape, including a distinct CPD plateau. The similar shape of the flow-phantom and in vivo curves suggests that the presence of a plateau can be used to identify the best-estimate CPD value in an in vivo experiment. The ability to identify the best CPD estimate is expected to improve quantification of angiogenesis and anti-angiogenic treatment responses with power Doppler.

  5. Color Doppler Ultrasound Velocimetry Flow Reconstruction using Vorticity-Streamfunction Formulation

    NASA Astrophysics Data System (ADS)

    Meyers, Brett; Vlachos, Pavlos; Goergen, Craig; Scalo, Carlo

    2016-11-01

    Clinicians commonly utilize Color Doppler imaging to qualitatively assess the velocity in patient cardiac or arterial flows. However Color Doppler velocity are restricted to two-dimensional one-component measurements. Recently new methods have been proposed to reconstruct a two-component velocity field from such data. Vector Flow Mapping (VFM), in particular, utilizes the conservation of mass to reconstruct the flow. However, this method over-simplifies the influence of wall and surrounding blood motion on local measurements, which produce large, non-physical velocity gradients, requiring excessive smoothing operations to remove. We propose a new approach based on the Vorticity-Stream Function (Ψ- ω) formulation that yields more physiologically accurate velocity gradients and avoids any added smoothing operations. Zero-penetration conditions are specified at the walls, removing the need for measurement of wall velocity from additional scans, which introduce further uncertainties in the reconstruction. Inflow and outflow boundary conditions are incorporated by prescribing Dirichlet boundary conditions. The proposed solver is compared against the VFM using computational data to evaluate measurement improvement. Finally we demonstrate the method by evaluating murine left ventricle Color Doppler scans.

  6. High-frequency ultrasound detection of cell death: Spectral differentiation of different forms of cell death in vitro

    PubMed Central

    Pasternak, Maurice M.; Sadeghi-Naini, Ali; Ranieri, Shawn M.; Giles, Anoja; Oelze, Michael L.; Kolios, Michael C.; Czarnota, Gregory J.

    2016-01-01

    High frequency quantitative ultrasound techniques were investigated to characterize different forms of cell death in vitro. Suspension-grown acute myeloid leukemia cells were treated to cause apoptosis, oncosis, mitotic arrest, and heat-induced death. Samples were scanned with 20 and 40 MHz ultrasound and assessed histologically in terms of cellular structure. Frequency-domain analysis of 20 MHz ultrasound data demonstrated midband fit changes of 6.0 ± 0.7 dBr, 6.2 ± 1.8 dBr, 4.0 ± 1.0 dBr and −4.6 ± 1.7 dBr after 48-hour cisplatinum-induced apoptosis, 48-hour oncotic decay, 36-hour colchicine-induced mitotic arrest, and heat treatment compared to control, respectively. Trends from 40 MHz ultrasound were similar. Spectral slope changes obtained from 40 MHz ultrasound data were reflective of alterations in cell and nucleus size. Chromatin pyknosis or lysis trends suggested that the density of nuclear material may be responsible for observed changes in ultrasound backscatter. Flow cytometry analysis confirmed the modes of cell death and supported midband fit trends in ultrasound data. Scatterer-size and concentration estimates obtained from a fluid-filled sphere form factor model further corresponded with spectral analysis and histology. Results indicate quantitative ultrasound spectral analysis may be used for probing anti-cancer response and distinguishing various modes of cell death in vitro. PMID:28050578

  7. TURBULENCE SPECTRA FROM DOPPLER-BROADENED SPECTRAL LINES: TESTS OF THE VELOCITY CHANNEL ANALYSIS AND VELOCITY COORDINATE SPECTRUM TECHNIQUES

    SciTech Connect

    Chepurnov, A.; Lazarian, A.

    2009-03-10

    Turbulent motions induce Doppler shifts of observable emission and absorption lines motivating studies of turbulence using precision spectroscopy. We provide numerical testing of the two most promising techniques, velocity channel analysis and velocity coordinate spectrum (VCS). We obtain an expression for the shot noise that the discretization of the numerical data entails and successfully test it. We show that the numerical resolution required for recovering the underlying turbulent spectrum from observations depend on the spectral index of velocity fluctuations, which makes low-resolution testing misleading. We demonstrate numerically that, when dealing with absorption lines, sampling of turbulence along just a dozen directions provides a high quality spectrum with the VCS technique.

  8. Contrast-enhanced ultrasound in combination with color Doppler ultrasound can improve the diagnostic performance of focal nodular hyperplasia and hepatocellular adenoma.

    PubMed

    Kong, Wen-Tao; Wang, Wen-Ping; Huang, Bei-Jian; Ding, Hong; Mao, Feng; Si, Qin

    2015-04-01

    The aim of our study was to evaluate the value of combining color Doppler ultrasound (CDUS) with contrast-enhanced ultrasound (CEUS) in identifying and comparing features of focal nodular hyperplasia (FNH) and hepatocellular adenoma (HCA). Thirty-eight patients with FNH (n = 28) or HCA (n = 10), whose diagnoses were later confirmed by pathology, were examined with conventional ultrasonography and CEUS between 2010 and 2013. Two doctors blinded to the pathology results independently reviewed the conventional ultrasound and CEUS images and then reached a consensus through discussion. The following parameters evaluated for all lesions included vascularity pattern on CDUS or CEUS, enhancement characteristics on CEUS and the presence of a central scar. Statistical analysis was performed with the independent sample t-test and Fisher exact test. On CDUS, FNH was characterized by the presence of abundant blood flow signals exhibiting dendritic (53.6%, 15/28) and spoke-wheel (28.6%, 8/28) patterns, whereas blood flow signal of HCA was slightly less than FNH and often showed subcapsular short rod-like (50%, 5/10) appearance. On CEUS, the most common arterial enhancement pattern was centrifugal or homogeneous enhancement in FNH (both, 12/28, 42.9%) and homogeneous enhancement in HCA (6/10, 60%). Spoke-wheel arteries, feeding artery and central scar were detected in 5 (17.9%), 8 (28.6%) and 5 (17.9%) of 28 FNHs. Hypo-echogenic pattern during delayed phase was more common in HCA (60%, 6/10) than in FNH (3/28, 10.7%) (p = 0.010). A total of 25 (25/38, 65.8%) lesions were correctly assessed using CDUS in combination with CEUS, whereas the number decreased to 15 (15/38, 39.5%) when CDUS was used alone (p = 0.038). The areas under the ROC curves before and after CEUS administration were 0.768 and 0.879, respectively. In conclusion, CEUS in combination with CDUS improve the diagnostic performance of FNH and HCA. Blood signal of HCA was less than FNH on CDUS. The differences of

  9. Is dynamic cerebral autoregulation measurement using transcranial Doppler ultrasound reproducible in the presence of high concentration oxygen and carbon dioxide?

    PubMed

    Minhas, Jatinder S; Syed, Nazia F; Haunton, Victoria J; Panerai, Ronney B; Robinson, Thompson G; Mistri, Amit K

    2016-05-01

    Reliability of cerebral blood flow velocity (CBFV) and dynamic cerebral autoregulation estimates (expressed as autoregulation index: ARI) using spontaneous fluctuations in blood pressure (BP) has been demonstrated. However, reliability during co-administration of O2 and CO2 is unknown. Bilateral CBFV (using transcranial Doppler), BP and RR interval recordings were performed in healthy volunteers (seven males, four females, age: 54  ±  10 years) on two occasions over 9  ±  4 d. Four 5 min recordings were made whilst breathing air (A), then 5%CO2 (C), 80%O2 (O) and mixed O2  +  CO2 (M), in random order. CBFV was recorded; ARI was calculated using transfer function analysis. Precision was quantified as within-visit standard error of measurement (SEM) and the coefficient of variation (CV). CBFV and ARI estimates with A (SEM: 3.85 & 0.87; CV: 7.5% & 17.8%, respectively) were comparable to a previous reproducibility study. The SEM and CV with C and O were similar, though higher values were noted with M; Bland-Altman plots indicated no significant bias across all gases for CBFV and ARI (bias  <0.06 cm s(-1) and  <0.05, respectively). Thus, transcranial-Doppler-ultrasound-estimated CBFV and ARI during inhalation of O2 and CO2 have acceptable levels of reproducibility and can be used to study the effect of these gases on cerebral haemodynamics.

  10. Mathematical modelling of the human foetal cardiovascular system based on Doppler ultrasound data.

    PubMed

    Pennati, G; Bellotti, M; Fumero, R

    1997-06-01

    A lumped parameter model of the human foetal circulation primarily based on blood velocity data derived from the Doppler analysis was developed in this study. It consists of two major parts, the heart and the foetal vascular circulation. The heart model accounts for both ventricular and atrial contractility. The circulation was divided into 19 compliant vascular compartments in order to describe all of the clinically monitored sites. The model parameters refer to the final gestation period and were derived either from literature on foetal sheep circulation or from anatomical dimension monitoring of the human foetus. No control mechanism is incorporated into the model. The model was validated by comparing several index values of simulated velocity curves to those of the experimental Doppler waveforms. The mean and maximum percentual errors in the estimation of the experimental results by the model are 7.7% and 20.1%, respectively. Velocity and pressure tracings of the foetal circulation were investigated, as well as regional blood flow rate distribution.

  11. Assessment of cerebral autoregulation with transcranial Doppler sonography in poor bone windows using constant infusion of an ultrasound contrast agent.

    PubMed

    Lorenz, Matthias W; Thoelen, Nina; Loesel, Nadine; Lienerth, Christian; Gonzalez, Marilen; Humpich, Marek; Roelz, Waltraud; Dvorak, Florian; Sitzer, Matthias

    2008-03-01

    Cerebral autoregulation is an important pathophysiological and prognostic parameter for a variety of neurologic conditions. It can be assessed quickly and safely using transcranial Doppler sonography (TCD). In elderly patients, poor insonation conditions decrease the number of examinable patients and can cause a systematic bias in autoregulation parameters. The aim of this study was to investigate whether a constant infusion of an ultrasound contrast agent (Levovist((R))) can counteract these effects. We examined two cohorts of unselected neurologic patients. In 45 patients with good insonation windows (cohort 1), we used a thin aluminium foil between the skin and the TCD probe to artificially decrease the insonation quality. We determined two parameters of cerebral autoregulation (phase difference [PD] and a cross-correlation coefficient [Mx]) in native patients, with aluminium foil and with aluminium foil and a constant infusion of Levovist. In 30 patients with poor insonation windows (cohort 2), we measured the autoregulation twice, with and without an infusion of Levovist, to assess the reproducibility of the autoregulation parameters. In cohort 1, the foil model significantly decreased the Doppler signal quality, i.e., the mean spectrum energy decreased from 33.9 +/- 2.7 dB to 26.3 +/- 2.4 dB (p < 0.001). This introduced a significant bias to all autoregulation parameters (PD: decreased from 38.2 +/- 10.0 degrees to 27.9 +/- 12.5 degrees (p < 0.001); Mx: decreased from 0.308 +/- 0.170 to 0.254 +/- 0.162 (p < 0.01)). Both effects were compensated largely by a constant infusion of Levovist (300 mg/min). In cohort 2, infusion of the contrast agent at the same rate increased insonation quality, too, but to a lesser degree (27.4 +/- 2.4 dB to 32.0 +/- 3.7 dB, p < 0.001). This smaller increase did not cause a significant change in the autoregulation parameters, but the reproducibility of the PD was significantly improved (intraclass coefficient coefficient [ICC] 0

  12. Ultrasound

    MedlinePlus

    ... your test will be done. Alternative Names Sonogram Images Abdominal ultrasound Ultrasound in pregnancy 17 week ultrasound ... urac.org). URAC's accreditation program is an independent audit to verify that A.D.A.M. follows ...

  13. Ultrasound

    MedlinePlus

    Ultrasound is a type of imaging. It uses high-frequency sound waves to look at organs and ... liver, and other organs. During pregnancy, doctors use ultrasound to view the fetus. Unlike x-rays, ultrasound ...

  14. Semen quality, testicular B-mode and Doppler ultrasound, and serum testosterone concentrations in dogs with established infertility.

    PubMed

    de Souza, Mírley Barbosa; England, Gary C W; Mota Filho, Antônio Cavalcante; Ackermann, Camila Louise; Sousa, Carmen Vládia Soares; de Carvalho, Gabriela Guedelha; Silva, Herlon Victor Rodrigues; Pinto, José Nicodemos; Linhares, Jussiara Candeira Spíndola; Oba, Eunice; da Silva, Lúcia Daniel Machado

    2015-09-15

    Retrospective examination of breeding records enabled the identification of 10 dogs of normal fertility and 10 dogs with established infertility of at least 12 months of duration. Comparisons of testicular palpation, semen evaluation, testicular ultrasound examination, Doppler ultrasound measurement of testicular artery blood flow, and measurement of serum testosterone concentration were made between the two groups over weekly examinations performed on three occasions. There were no differences in testicular volume (cm(3)) between the two groups (fertile right testis = 10.77 ± 1.66; fertile left testis = 12.17 ± 2.22); (infertile right testis = 10.25 ± 3.33; infertile left testis = 11.37 ± 3.30), although the infertile dogs all had subjectively softer testes compared with the fertile dogs. Infertile dogs were either azoospermic or when they ejaculated, they had lower sperm concentration, sperm motility, and percentage of morphologically normal spermatozoa than fertile dogs. Furthermore, infertile dogs had reduced sperm membrane integrity measured via the hypoosmotic swelling test. Infertile dogs had significantly lower basal serum testosterone concentrations (1.40 ± 0.62 ng/mL) than fertile dogs (1.81 ± 0.87 ng/mL; P < 0.05). There were subjective differences in testicular echogenicity in some of the infertile dogs, and important differences in testicular artery blood flow with lower peak systolic and end-diastolic velocities measured in the distal supratesticular artery, marginal testicular artery, and intratesticular artery of infertile dogs (P < 0.05). Notably, resistance index and pulsatility index did not differ between infertile and fertile dogs. These findings report important differences between infertile and fertile dogs which may be detected within an expanded breeding soundness examination.

  15. 5D interactive real time Doppler ultrasound visualization of the heart

    NASA Astrophysics Data System (ADS)

    Heid, Volker; Evers, Harald; Henn, Christian; Glombitza, Gerald; Meinzer, Hans-Peter

    2000-04-01

    Heart valve insufficiencies can optimally be assessed using transesophageal, triggered, three-dimensional ultrasound imaging. The dynamic ultrasound data contain morphological as well as functional components which are recorded and displayed simultaneously. It allows the visualization of intracardiac motion which is an important parameter to detect abnormal flow caused by defect valves. A realtime reconstruction is desired to get a spatial impression on the one hand and to interactively clip parts of the volume on the other hand. OpenGL Volumizer is used for visualization. Scalability of the visualization was tested with respect to different workstations and graphics resources using a Multipipe Utility library (MPU). The combination of both APIs enables a visualization of volumetric and functional data with frame rates up to 10 frames per second. By using the proposed method, it is possible to visualize the jet in the original color-coding which is employed during a conventional two- dimensional examination for displaying the velocity values. A good scalability from low cost up to high end graphic workstations is given by the use of the MPU. The quality of the resulting 3D images allows exact differentiation of heart valve insufficiencies to support the diagnostic procedure.

  16. Can simple clinical features be used to identify patients with severe carotid stenosis on Doppler ultrasound?

    PubMed Central

    Mead, G.; Wardlaw, J.; Lewis, S.; McDowall, M.; Dennis, M.

    1999-01-01

    OBJECTIVES—Carotid endarterectomy reduces the risk of stroke in symptomatic patients with severe ipsilateral carotid stenosis. Symptomatic patients should therefore undergo carotid Doppler imaging, but in some centres access to imaging is limited. It was therefore investigated whether simple clinical features alone or in combination could be used to identify patients with severe carotid stenosis, so that they could be referred preferentially for carotid imaging.
METHODS—1041 patients with acute stroke, cerebral or retinal transient ischaemic attacks, and retinal strokes admitted to Western General Hospital or seen in neurovascular clinics were assessed by a stroke physician. Their carotid arteries were investigated using colour Doppler imaging by a consultant neuroradiologist. Patients with primary intracerebral haemorrhage, total anterior circulation strokes, posterior circulation strokes, or posterior circulation transient ischaemic attacks were excluded because carotid surgery would be inappropriate.
RESULTS—726 patients were used in the analysis. Stepwise logistic regression showed that there were significant positive associations between severe carotid stenosis and an ipsilateral bruit, diabetes mellitus, and previous transient ischaemic attacks; and a negative association with lacunar events. The strategy with the highest specificity (97%) was "any three of these four features" but sensitivity was only 17%. The strategy with the highest sensitivity (99%) was to use one or more of the four features, but specificity was only 22%.
CONCLUSION—None of the strategies identified all patients with severe carotid stenosis with a reasonable specificity. When access to carotid imaging is severely limited, simple clinical features are of some use in prioritising patients for imaging, but access to carotid imaging should be improved. 

 PMID:9886444

  17. Assessment of flow distribution in the mouse fetal circulation at late gestation by high-frequency Doppler ultrasound.

    PubMed

    Zhou, Yu-Qing; Cahill, Lindsay S; Wong, Michael D; Seed, Mike; Macgowan, Christopher K; Sled, John G

    2014-08-15

    This study used high-frequency ultrasound to evaluate the flow distribution in the mouse fetal circulation at late gestation. We studied 12 fetuses (embryonic day 17.5) from 12 pregnant CD1 mice with 40 MHz ultrasound to assess the flow in 11 vessels based on Doppler measurements of blood velocity and M-mode measurements of diameter. Specifically, the intrahepatic umbilical vein (UVIH), ductus venosus (DV), foramen ovale (FO), ascending aorta (AA), main pulmonary artery (MPA), ductus arteriosus (DA), descending thoracic aorta (DTA), common carotid artery (CCA), inferior vena cava (IVC), and right and left superior vena cavae (RSVC, LSVC) were examined, and anatomically confirmed by micro-CT. The mouse fetal circulatory system was found to be similar to that of the humans in terms of the major circuit and three shunts, but characterized by bilateral superior vena cavae and a single umbilical artery. The combined cardiac output (CCO) was 1.22 ± 0.05 ml/min, with the left ventricle (flow in AA) contributing 47.8 ± 2.3% and the right ventricle (flow in MPA) 52.2 ± 2.3%. Relative to the CCO, the flow percentages were 13.6 ± 1.0% for the UVIH, 10.4 ± 1.1% for the DV, 35.6 ± 2.4% for the DA, 41.9 ± 2.6% for the DTA, 3.8 ± 0.3% for the CCA, 29.5 ± 2.2% for the IVC, 12.7 ± 1.0% for the RSVC, and 9.9 ± 0.9% for the LSVC. The calculated flow percentage was 16.6 ± 3.4% for the pulmonary circulation and 31.2 ± 5.3% for the FO. In conclusion, the flow in mouse fetal circulation can be comprehensively evaluated with ultrasound. The baseline data of the flow distribution in normal mouse fetus serve as the reference range for future studies.

  18. Monitoring cancer treatment response using photoacoustic and ultrasound spectral analysis in combination with oxygenation measurements (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Hysi, Eno; May, Jonathan P.; Wirtzfeld, Lauren; Undzys, Elijus; Li, Shyh-Dar; Kolios, Michael C.

    2016-03-01

    At clinically-relevant depths, the frequency content of photoacoustic signals encodes information about the size, concentration and spatial distribution of non-resolvable blood vessels. This study evaluates whether photoacoustics can detect cancer therapy-induced vascular perturbations. Photoacoustic/ultrasound (PA/US) spectral analysis was combined with functional, PA-based oxygenation and power Doppler (PD) perfusion estimates to assess treatment response. Co-registered, in-vivo US/PA/PD imaging of mice bearing breast cancer tumors was performed pre-treatment and 30m/2h/5h/24h/7d post-treatment (VevoLAZR, Fujifilm VisualSonics). Hyperthermia treatment (1h, 43C) was performed after systemic injections of doxorubicin-loaded thermosensitive liposomes (TSL, n=13) or free doxorubicin (DOX, n=11). Response was classified according to 2h, PA-based oxygenation drop and endpoint (>9d), caliper-based volume reduction. At all time-points/wavelengths (750/850nm), the spectral-slope (SS) was computed from the normalized US/PA power spectra using depth-matched reference phantoms. The percent-vascularity (PV) was estimated for the animal with the largest oxygenation-drop at 2h. TLS-treated responders decreased their PA-SS by 1.9x @750nm and 5.8x @850nm 30m post-treatment and remained constant for 24h; tumor oxygenation followed the same trend. Non-responding SS remained unchanged for 24h. The 750nm SS was 18.7x lower than 850nm suggesting the TSL is sensitive vessel oxygenation. Responder PV decreased 100% when the 30m oxygenation dropped 15% and increased 7x when the 7d oxygenation increased 20%. DOX-responders exhibited similar trends to TSL-responders although the 750nm PA-SS was 1.6x smaller and post-treatment PV was 50% higher. The US-SS remained unchanged until 7d post-treatment suggesting its sensitivity to tumor cell-death. These findings suggest that PA spectral analysis has potential in monitoring cancer treatment response.

  19. Transrectal Ultrasound-Integrated Spectral Optical Tomography of Hypoxic Progression of a Regressing Tumor in a Canine Prostate

    PubMed Central

    Jiang, Z.; Piao, D.; Bartels, K. E.; Holyoak, G. R.; Ritchey, J. W.; Ownby, C. L.; Rock, K.; Slobodov, G.

    2011-01-01

    The objective of this study was to evaluate if transrectal optical tomography implemented at three wavelength bands for spectral detection could monitor changes of the hemoglobin oxygen saturation (StO2) in addition to those of the total hemoglobin concentration ([HbT]) in lesions of a canine prostate, including an induced tumor modeling canine prostate cancer. Near-infrared (NIR) optical tomography was integrated with ultrasound (US) for transrectal imaging. Multi-spectral detection at 705 nm, 785 nm and 808 nm rendered measurements of [HbT] and StO2. Canine transmissible venereal tumor (TVT) cells were injected into the right lobe of a dog's prostate gland, which had a pre-existing cyst in the left lobe. Longitudinal assessments of the prostate were performed weekly over a 63-day duration by NIR imaging concurrent with grey-scale and Doppler US. Ultrasonography revealed a bi-lobular tumor-mass regressing from day-49 to day-63. At day-49 this tumor-mass developed a hypoxic core that became larger and more intense by day-56 and expanded further by day-63. The tumor-mass presented a strong hyper-[HbT] feature on day-56 that was inconsistent with US-visualized blood flow. Histology confirmed two necrotic TVT foci within this tumor-mass. The cyst appeared to have a large anoxic-like interior that was greater in size than its ultrasonographically delineated lesion, and a weak lesional elevation of [HbT]. On day-56, the cyst presented a strong hyper-[HbT] feature consistent with US-resolved blood flow. Histology revealed acute and chronic hemorrhage in the periphery of the cyst. The NIR imaging features of two other TVT nodules and a metastatic lymph node were evaluated retrospectively. Transrectal US-integrated spectral optical tomography seems to enable longitudinal monitoring of intra-lesional oxygenation dynamics in addition to the hemoglobin content of lesions in the canine prostate. PMID:22066593

  20. Transcranial Doppler ultrasound blood flow velocity and pulsatility index as systemic indicators for Alzheimer’s disease

    PubMed Central

    Roher, Alex E.; Garami, Zsolt; Tyas, Suzanne L.; Maarouf, Chera L.; Kokjohn, Tyler A.; Belohlavek, Marek; Vedders, Linda J.; Connor, Donald; Sabbagh, Marwan N.; Beach, Thomas G.; Emmerling, Mark R.

    2010-01-01

    Background Multiple lines of evidence suggest cardiovascular co-morbidities hasten the onset of Alzheimer’s disease (AD) or accelerate its course. Methods To evaluate the utility of cerebral vascular physical function/condition parameters as potential systemic indicators of AD, we employed transcranial Doppler (TCD) ultrasound to assess cerebral blood flow and vascular resistance of the 16 arterial segments comprising the circle of Willis and its major tributaries. Results Our study revealed decreased arterial mean flow velocity (MFV) and increased pulsatility index (PI) are associated with a clinical diagnosis of presumptive AD. Cerebral blood flow impairment revealed by these parameters reflects the global hemodynamic and structural consequences of a multifaceted disease process yielding diffuse congestive microvascular pathology, increased arterial rigidity, and decreased arterial compliance combined with putative age-associated cardiovascular output declines. Conclusions TCD evaluation offers direct physical confirmation of brain perfusion impairment and may ultimately provide a convenient, noninvasive means to assess the efficacy of medical interventions on cerebral blood flow or reveal incipient AD. In the near term, TCD-based direct assessments of brain perfusion may offer the prospect of preventing or mitigating AD simply by revealing patients who would benefit from interventions to improve circulatory system function. PMID:21388892

  1. Does cerebral lateralization develop? A study using functional transcranial Doppler ultrasound assessing lateralization for language production and visuospatial memory.

    PubMed

    Groen, Margriet A; Whitehouse, Andrew J O; Badcock, Nicholas A; Bishop, Dorothy V M

    2012-05-01

    In the majority of people, language production is lateralized to the left cerebral hemisphere and visuospatial skills to the right. However, questions remain as to when, how, and why humans arrive at this division of labor. In this study, we assessed cerebral lateralization for language production and for visuospatial memory using functional transcranial Doppler ultrasound in a group of 60 typically developing children between the ages of six and 16 years. The typical pattern of left-lateralized activation for language production and right-lateralized activation for visuospatial memory was found in the majority of the children (58%). No age-related change in direction or strength of lateralization was found for language production. In contrast, the strength of lateralization (independent of direction) for visuospatial memory function continued to increase with age. In addition, boys showed a trend for stronger right-hemisphere lateralization for visuospatial memory than girls, but there was no gender effect on language laterality. We tested whether having language and visuospatial functions in the same hemisphere was associated with poor cognitive performance and found no evidence for this "functional crowding" hypothesis. We did, however, find that children with left-lateralized language production had higher vocabulary and nonword reading age-adjusted standard scores than other children, regardless of the laterality of visuospatial memory. Thus, a link between language function and left-hemisphere lateralization exists, and cannot be explained in terms of maturational change.

  2. Comparison of spectral estimation methods in reconstruction of parametric ultrasound images

    NASA Astrophysics Data System (ADS)

    Chaturvedi, Pawan; Insana, Michael F.; Hall, Timothy J.

    1996-04-01

    The application of inverse scattering methods to diagnostic ultrasound echo signals has provided us with detailed information about renal microstructure and function. In particular, the average scatterer size has been used to follow changes in microvascular perfusion that occur early in many renal disease processes. This paper shows that by introducing prior knowledge of the tissue state into the process, uncertainty in the spectral estimate is reduced for low SNR situations, and the contrast and range-resolution in scatterer size images can be improved without increasing the noise. Prior information used in the estimation technique is obtained from the histology of biological tissue. Maximum a posteriori and constrained least squares estimators are designed to obtain images for different levels of noise and for different gate-durations. Prior knowledge about the noise properties and the nature of the echo spectrum is used to obtain the order of an autoregressive model for estimating the power spectral density.

  3. A Semiempirical Model for Doppler Spectral Features of Microwave Radar Sea Scatter.

    DTIC Science & Technology

    1985-10-16

    small to moderate wave heights, a point on the sea surface moves in a circular orbit as a large wave passes by. Under these conditions, the linear...Interactions on the Second-order Doppler Spectrum of Sea Echo," JGR 79, 5031-5037 (1974). 4. B.L. Hicks, N. Knable, J.J. Kovaly, G.S. Newell, J.P. Ruina , and

  4. Inverse Problem for Color Doppler Ultrasound-Assisted Intracardiac Blood Flow Imaging

    PubMed Central

    Jang, Jaeseong

    2016-01-01

    For the assessment of the left ventricle (LV), echocardiography has been widely used to visualize and quantify geometrical variations of LV. However, echocardiographic image itself is not sufficient to describe a swirling pattern which is a characteristic blood flow pattern inside LV without any treatment on the image. We propose a mathematical framework based on an inverse problem for three-dimensional (3D) LV blood flow reconstruction. The reconstruction model combines the incompressible Navier-Stokes equations with one-direction velocity component of the synthetic flow data (or color Doppler data) from the forward simulation (or measurement). Moreover, time-varying LV boundaries are extracted from the intensity data to determine boundary conditions of the reconstruction model. Forward simulations of intracardiac blood flow are performed using a fluid-structure interaction model in order to obtain synthetic flow data. The proposed model significantly reduces the local and global errors of the reconstructed flow fields. We demonstrate the feasibility and potential usefulness of the proposed reconstruction model in predicting dynamic swirling patterns inside the LV over a cardiac cycle. PMID:27313657

  5. Denoising embolic Doppler ultrasound signals using Dual Tree Complex Discrete Wavelet Transform.

    PubMed

    Serbes, Gorkem; Aydin, Nizamettin

    2010-01-01

    Early and accurate detection of asymptomatic emboli is important for monitoring of preventive therapy in stroke-prone patients. One of the problems in detection of emboli is the identification of an embolic signal caused by very small emboli. The amplitude of the embolic signal may be so small that advanced processing methods are required to distinguish these signals from Doppler signals arising from red blood cells. In this study instead of conventional discrete wavelet transform, the Dual Tree Complex Discrete Wavelet Transform was used for denoising embolic signals. Performances of both approaches were compared. Unlike the conventional discrete wavelet transform discrete complex wavelet transform is a shift invariant transform with limited redundancy. Results demonstrate that the Dual Tree Complex Discrete Wavelet Transform based denoising outperforms conventional discrete wavelet denoising. Approximately 8 dB improvement is obtained by using the Dual Tree Complex Discrete Wavelet Transform compared to the improvement provided by the conventional Discrete Wavelet Transform (less than 5 dB).

  6. Characterization of intraventricular flow patterns in healthy neonates from conventional color-Doppler ultrasound

    NASA Astrophysics Data System (ADS)

    Tejman-Yarden, Shai; Rzasa, Callie; Benito, Yolanda; Alhama, Marta; Leone, Tina; Yotti, Raquel; Bermejo, Javier; Printz, Beth; Del Alamo, Juan C.

    2012-11-01

    Left ventricular vortices have been difficult to visualize in the clinical setting due to the lack of quantitative non-invasive modalities, and this limitation is especially important in pediatrics. We have developed and validated a new technique to reconstruct two-dimensional time-resolved velocity fields in the LV from conventional transthoracic color-Doppler images. This non-invasive modality was used to image LV flow in 10 healthy full-term neonates, ages 24-48 hours. Our results show that, in neonates, a diastolic vortex developed during LV filling, was maintained during isovolumic contraction, and decayed during the ejection period. The vortex was created near the base of the ventricle, moved toward the apex, and then back toward the base and LVOT during ejection. In conclusion, we have characterized for the first time the properties of the LV filling vortex in normal neonates, demonstrating that this vortex channels blood from the inflow to the outflow tract of the LV. Together with existing data from adults, our results confirm that the LV vortex is conserved through adulthood. Funded by NIH Grant R21HL108268.

  7. Use of Transcranial Doppler Ultrasound for Diagnosis of Brain Death in Patients with Severe Cerebral Injury.

    PubMed

    Li, Yuequn; Liu, Shangwei; Xun, Fangfang; Liu, Zhan; Huang, Xiuying

    2016-06-06

    BACKGROUND The aim of this study was to investigate the use of transcranial Doppler (TCD) for diagnosis of brain death in patients with severe cerebral injury. MATERIAL AND METHODS This retrospective study enrolled 42 patients based on inclusion and exclusion criteria. All patients were divided into either the brain death group or the survival group according to prognosis. Blood flow of the brain was examined by TCD and analyzed for spectrum changes. The average blood flow velocity (Vm), pulse index (PI), and diastolic blood flow in reverse (RDF) were recorded and compared. RESULTS The data demonstrated that the average speed of bilateral middle cerebral artery blood flow in the brain death group was significantly reduced (P<0.05). However, the PI of the brain death group increased significantly. Moreover, RDF spectrum and nail-like sharp peak spectrum of the brain death group was higher than in the survival group. CONCLUSIONS Due to its simplicity, high repeatability, and specificity, TCD combined with other methods is highly valuable for diagnosis of brain death in patients with severe brain injury.

  8. Effect of velocity profile skewing on blood velocity and volume flow waveforms derived from maximum Doppler spectral velocity.

    PubMed

    Mynard, Jonathan P; Steinman, David A

    2013-05-01

    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.

  9. En face Doppler total retinal blood flow measurement with 70 kHz spectral optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Tan, Ou; Liu, Gangjun; Liang, Liu; Gao, Simon S.; Pechauer, Alex D.; Jia, Yali; Huang, David

    2015-06-01

    An automated algorithm was developed for total retinal blood flow (TRBF) using 70-kHz spectral optical coherence tomography (OCT). The OCT was calibrated for the transformation from Doppler shift to speed based on a flow phantom. The TRBF scan pattern contained five repeated volume scans (2×2 mm) obtained in 3 s and centered on central retinal vessels in the optic disc. The TRBF was calculated using an en face Doppler technique. For each retinal vein, blood flow was measured at an optimal plane where the calculated flow was maximized. The TRBF was calculated by summing flow in all veins. The algorithm tracked vascular branching so that either root or branch veins are summed, but never both. The TRBF in five repeated volumes were averaged to reduce variation due to cardiac cycle pulsation. Finally, the TRBF was corrected for eye length variation. Twelve healthy eyes and 12 glaucomatous eyes were enrolled to test the algorithm. The TRBF was 45.4±6.7 μl/min for healthy control and 34.7±7.6 μl/min for glaucomatous participants (p-value=0.01). The intravisit repeatability was 8.6% for healthy controls and 8.4% for glaucoma participants. The proposed automated method provided repeatable TRBF measurement.

  10. En face Doppler total retinal blood flow measurement with 70 kHz spectral optical coherence tomography

    PubMed Central

    Tan, Ou; Liu, Gangjun; Liang, Liu; Gao, Simon S.; Pechauer, Alex D.; Jia, Yali; Huang, David

    2015-01-01

    Abstract. An automated algorithm was developed for total retinal blood flow (TRBF) using 70-kHz spectral optical coherence tomography (OCT). The OCT was calibrated for the transformation from Doppler shift to speed based on a flow phantom. The TRBF scan pattern contained five repeated volume scans (2×2  mm) obtained in 3 s and centered on central retinal vessels in the optic disc. The TRBF was calculated using an en face Doppler technique. For each retinal vein, blood flow was measured at an optimal plane where the calculated flow was maximized. The TRBF was calculated by summing flow in all veins. The algorithm tracked vascular branching so that either root or branch veins are summed, but never both. The TRBF in five repeated volumes were averaged to reduce variation due to cardiac cycle pulsation. Finally, the TRBF was corrected for eye length variation. Twelve healthy eyes and 12 glaucomatous eyes were enrolled to test the algorithm. The TRBF was 45.4±6.7  μl/min for healthy control and 34.7±7.6  μl/min for glaucomatous participants (p-value=0.01). The intravisit repeatability was 8.6% for healthy controls and 8.4% for glaucoma participants. The proposed automated method provided repeatable TRBF measurement. PMID:26062663

  11. Ray tracing model for the estimation of power spectral properties in laser Doppler velocimetry of retinal vessels and its potential application to retinal vessel oximetry

    NASA Astrophysics Data System (ADS)

    Petrig, Benno L.; Follonier, Lysianne

    2005-12-01

    A new model based on ray tracing was developed to estimate power spectral properties in laser Doppler velocimetry of retinal vessels and to predict the effects of laser beam size and eccentricity as well as absorption of laser light by oxygenated and reduced hemoglobin. We describe the model and show that it correctly converges to the traditional rectangular shape of the Doppler shift power spectrum, given the same assumptions, and that reduced beam size and eccentric alignment cause marked alterations in this shape. The changes in the detected total power of the Doppler-shifted light due to light scattering and absorption by blood can also be quantified with this model and may be used to determine the oxygen saturation in retinal arteries and veins. The potential of this approach is that it uses direct measurements of Doppler signals originating from moving red blood cells. This may open new avenues for retinal vessel oximetry.

  12. Noninvasive assessment of sympathetic vasoconstriction in human and rodent skeletal muscle using near-infrared spectroscopy and Doppler ultrasound.

    PubMed

    Fadel, Paul J; Keller, David M; Watanabe, Hitoshi; Raven, Peter B; Thomas, Gail D

    2004-04-01

    The precise role of the sympathetic nervous system in the regulation of skeletal muscle blood flow during exercise has been challenging to define in humans, partly because of the limited techniques available for measuring blood flow in active muscle. Recent studies using near-infrared (NIR) spectroscopy to measure changes in tissue oxygenation have provided an alternative method to evaluate vasomotor responses in exercising muscle, but this approach has not been fully validated. In this study, we tested the hypothesis that sympathetic activation would evoke parallel changes in tissue oxygenation and blood flow in resting and exercising muscle. We simultaneously measured tissue oxygenation with NIR spectroscopy and blood flow with Doppler ultrasound in skeletal muscle of conscious humans (n = 13) and anesthetized rats (n = 9). In resting forearm of humans, reflex activation of sympathetic nerves with the use of lower body negative pressure produced graded decreases in tissue oxygenation and blood flow that were highly correlated (r = 0.80, P < 0.0001). Similarly, in resting hindlimb of rats, electrical stimulation of sympathetic nerves produced graded decreases in tissue oxygenation and blood flow velocity that were highly correlated (r = 0.93, P < 0.0001). During rhythmic muscle contraction, the decreases in tissue oxygenation and blood flow evoked by sympathetic activation were significantly attenuated (P < 0.05 vs. rest) but remained highly correlated in both humans (r = 0.80, P < 0.006) and rats (r = 0.92, P < 0.0001). These data indicate that, during steady-state metabolic conditions, changes in tissue oxygenation can be used to reliably assess sympathetic vasoconstriction in both resting and exercising skeletal muscle.

  13. Studying cerebral hemodynamics and metabolism using simultaneous near-infrared spectroscopy and transcranial Doppler ultrasound: a hyperventilation and caffeine study

    PubMed Central

    Yang, Runze; Brugniaux, Julien; Dhaliwal, Harinder; Beaudin, Andrew E; Eliasziw, Misha; Poulin, Marc J; Dunn, Jeff F

    2015-01-01

    Caffeine is one of the most widely consumed psycho-stimulants in the world, yet little is known about its effects on brain oxygenation and metabolism. Using a double-blind, placebo-controlled, randomized cross-over study design, we combined transcranial Doppler ultrasound (TCD) and near-infrared spectroscopy (NIRS) to study caffeine's effect on middle cerebral artery peak blood flow velocity (Vp), brain tissue oxygenation (StO2), total hemoglobin (tHb), and cerebral oxygen metabolism (CMRO2) in five subjects. Hyperventilation-induced hypocapnia served as a control to verify the sensitivity of our measurements. During hypocapnia (∼16 mmHg below resting values), Vp decreased by 40.0 ± 2.4% (95% CI, P < 0.001), while StO2 and tHb decreased by 2.9 ± 0.3% and 2.6 ± 0.4%, respectively (P = 0.003 and P = 0.002, respectively). CMRO2, calculated using the Fick equation, was reduced by 29.3 ± 9% compared to the isocapnic-euoxia baseline (P < 0.001). In the pharmacological experiments, there was a significant decrease in Vp, StO2, and tHb after ingestion of 200 mg of caffeine compared with placebo. There was no significant difference in CMRO2 between caffeine and placebo. Both showed a CMRO2 decline compared to baseline showing the importance of a placebo control. In conclusion, this study showed that profound hypocapnia impairs cerebral oxidative metabolism. We provide new insight into the effects of caffeine on cerebral hemodynamics. Moreover, this study showed that multimodal NIRS/TCD is an excellent tool for studying brain hemodynamic responses to pharmacological interventions and physiological challenges. PMID:25907789

  14. Splanchnic Hemodynamics and Intestinal Vascularity in Crohn's Disease: An In Vivo Evaluation Using Doppler and Contrast-Enhanced Ultrasound and Biochemical Parameters.

    PubMed

    Maconi, Giovanni; Asthana, Anil K; Bolzacchini, Elena; Dell'Era, Alessandra; Furfaro, Federica; Bezzio, Cristina; Salvatore, Veronica; Maier, Jeanette A M

    2016-01-01

    Crohn's disease (CD) is characterized by inflammation and angiogenesis of affected bowel. We evaluated the correlation among vascularity of intestinal wall in CD, splanchnic hemodynamics, clinical activity and biochemical parameters of inflammation and angiogenesis. Sixteen patients with ileal CD and 10 healthy controls were investigated by means of Doppler ultrasound of the superior mesenteric artery and color Doppler and contrast-enhanced ultrasound of the ileal wall. In parallel, serum levels of vascular endothelial growth factor, tumor necrosis factor-α (TNF-α) and nitric oxide, before and 30 min after a standard meal, were evaluated. In CD patients, there was a significant post-prandial reduction in the resistance index and pulsatility index of the superior mesenteric artery, associated with increased levels of nitric oxide and decreased amounts of TNF-α. A correlation was observed between vascular endothelial growth factor and contrast-enhanced ultrasound parameters of intestinal wall vascularity (r = 0.63-0.71, p < 0.05) and between these parameters and superior mesenteric artery blood flow after fasting (resistance and pulsatility indexes: r = -0.64 and -0.72, p < 0.05). Our results revealed a post-prandial increase in nitric oxide and decrease in TNF-α in CD patients in vivo. They also confirm the role of vascular endothelial growth factor in angiogenesis and in pathologic vascular remodeling of CD and its effect on splanchnic blood flow.

  15. The effects of probe placement on measured flow velocity in transcranial Doppler ultrasound imaging in-vitro and in-vivo experiments

    NASA Astrophysics Data System (ADS)

    de Jong, Daan L. K.; Meel-van den Abeelen, Aisha S. S.; Lagro, Joep; Claassen, Jurgen A. H. R.; Slump, Cornelis H.

    2014-03-01

    The measurement of the blood flow in the middle cerebral artery (MCA) using transcranial Doppler ultrasound (US) imaging is clinically relevant for the study of cerebral autoregulation. Especially in the aging population, impairement of the autoregulation may coincide or relate to loss of perfusion and consequently loss of brain function. The cerebral autoregulation can be assessed by relating the blood pressure to the blood flow in the brain. Doppler US is a widely used, non-invasive method to measure the blood flow in the MCA. However, Doppler flow imaging is known to produce results that are dependent of the operator. The angle of the probe insonation with respect to the centerline of the blood vessel is a well known factor for output variability. In patients also the skull must be traversed and the MCA must be detected, influencing the US signal intensity. In this contribution we report two studies. We describe first an in-vitro setup to study the Doppler flow in a situation where the ground truth is known. Secondly, we report on a study with healthy volunteers where the effects of small probe displacements on the flow velocity signals are investigated. For the latter purpose, a special probe holder was designed to control the experiment.

  16. Microcrack Quantification in Composite Materials by a Neural Network Analysis of Ultrasound Spectral Data

    NASA Technical Reports Server (NTRS)

    Walker, James L.; Russell, Samuel S.; Suits, Michael W.

    2003-01-01

    Intra-ply microcracking in unlined composite pressure vessels can be very troublesome to detect and when linked through the thickness can provide leak paths that may hinder mission success. The leaks may lead to loss of pressure/propellant, increased risk of explosion and possible cryo-pumping into air pockets within the laminate. Ultrasonic techniques have been shown capable of detecting the presence of microcracking and in this work they are used to quantify the level of microcracking. Resonance ultrasound methods are utilized with artificial neural networks to build a microcrack prediction/measurement tool. Two networks are presented, one unsupervised to provide a qualitative measure of microcracking and one supervised which provides a quantitative assessment of the level of microcracking. The resonant ultrasound spectroscopic method is made sensitive to microcracking by tuning the input spectrum to the higher frequency (shorter wavelength) components allowing more significant interaction with the defects. This interaction causes the spectral characteristics to shift toward lower amplitudes at the higher frequencies. As the density of the defects increases more interactions occur and more drastic amplitude changes are observed. Preliminary experiments to quantify the level of microcracking induced in graphite/epoxy composite samples through a combination of tensile loading and cryogenic temperatures are presented. Both unsupervised (Kohonen) and supervised (radial basis function) artificial neural networks are presented to determine the measurable effect on the resonance spectrum of the ultrasonic data taken from the samples.

  17. Ultrasound Annual, 1984

    SciTech Connect

    Sanders, R.C.; Hill, M.C.

    1984-01-01

    The 1984 edition of Ultrasound Annual explores new applications of ultrasound in speech and swallowing and offers guidelines on the use of ultrasound and nuclear medicine in thyroid and biliary tract disease. Other areas covered include Doppler sonography of the abdomen, intraoperative abdominal ultrasound, sonography of the placenta, ultrasound of the neonatal head and abdomen, and sonographic echo patterns created by fat.

  18. Magnetic local time, substorm, and particle precipitation-related variations in the behaviour of SuperDARN Doppler spectral widths

    NASA Astrophysics Data System (ADS)

    Parkinson, M.; Chisham, G.; Pinnock, M.; Dyson, P.; Devlin, J.

    2004-12-01

    Super Dual Auroral Radar Network (DARN) radars often detect a distinct transition in line-of-sight Doppler velocity spread, or spectral width, from <50ms-1 at lower latitude to >200ms-1 at higher latitude. They also detect a similar boundary, namely the range at which ionospheric scatter with large spectral width suddenly commences (i.e. without preceding scatter with low spectral width). The location and behaviour of the spectral width boundary (SWB) (and scatter boundary) and the open-closed magnetic field line boundary (OCB) are thought to be closely related. The location of the nightside OCB can be inferred from the poleward edge of the auroral oval determined using energy spectra of precipitating particles measured on board Defence Meteorology Satellite Program (DMSP) satellites. Observations made with the Halley SuperDARN radar (75.5° S, 26.6° W, geographic; -62.0°Λ) and the Tasman International Geospace Environment Radar (TIGER) (43.4° S, 147.2° E; -54.5°Λ) are used to compare the location of the SWB with the DMSP-inferred OCB during 08:00 to 22:00 UT on 1 April 2000. This study interval was chosen because it includes several moderate substorms, whilst the Halley radar provided almost continuous high-time resolution measurements of the dayside SWB location and shape, and TIGER provided the same in the nightside ionosphere. The behaviour of the day- and nightside SWB can be understood in terms of the expanding/contracting polar cap model of high-latitude convection change, and the behaviour of the nightside SWB can also be organised according to substorm phase. Previous comparisons with DMSP OCBs have proven that the radar SWB is often a reasonable proxy for the OCB from dusk to just past midnight (Chisham et al., 2004). However, the present case study actually suggests that the nightside SWB is often a better proxy for the poleward edge of Pedersen conductance enhanced by hot particle precipitation in the auroral zone. Simple modeling implies that

  19. Phentolamine re-dosing during penile dynamic colour Doppler ultrasound: a practical method to abolish a false diagnosis of venous leakage in patients with erectile dysfunction.

    PubMed

    Gontero, P; Sriprasad, S; Wilkins, C J; Donaldson, N; Muir, G H; Sidhu, P S

    2004-11-01

    Increased sympathetic tone may cause an equivocal response to a prostaglandin E1 (PGE1) penile Doppler ultrasound (US) examination interpreted as a venous leak. We evaluated the US parameters and erectile response to the addition of phentolamine to a PGE1 penile Doppler US examination to ascertain whether addition of phentolamine would abolish a suboptimal response. 32 patients (median age 29 years, range 17-70 years) with either a previous Doppler US pattern of venous leakage or a clinical suspicion of venogenic impotence, underwent Doppler US after a total dose of 20 microg of PGE1. Peak systolic velocity (PSV), end diastolic velocity (EDV) and grade of erection were documented. If erectile response was suboptimal irrespective of the EDV measurement, 2 mg-intracavernosal phentolamine was administered and measurements repeated. Six patients had a normal erectile response, the remaining 26 received phentolamine. A significant increase in PSV between baseline and 20 microg PGE1 (p<0.001) was observed in all cases. Following phentolamine there was a significant increase in grade of erection (p=0.0001) and a significant reduction in the EDV (p=0.0001). A reduction of the EDV to below 0.0 cm s(-1) was observed in 16 patients. Four patients with EDV <5.0 cm s(-1) but >0.0 cm s(-1) had improved erectile response following phentolamine while six showed persistent EDV elevation >5 cm s(-1). No priapism was documented. It is essential to ensure cavernosal relaxation using phentolamine before a Doppler US diagnosis of venous leak is made. This two-stage assessment will allow this to be done efficiently and with a low risk of priapism.

  20. Seminal, clinical and colour-Doppler ultrasound correlations of prostatitis-like symptoms in males of infertile couples.

    PubMed

    Lotti, F; Corona, G; Mondaini, N; Maseroli, E; Rossi, M; Filimberti, E; Noci, I; Forti, G; Maggi, M

    2014-01-01

    'Prostatitis-like symptoms' (PLS) are a cluster of bothersome conditions defined as 'perineal and/or ejaculatory pain or discomfort and National Institutes of Health-Chronic Prostatitis Symptom Index (NIH-CPSI) pain subdomain score ≥4' (Nickel's criteria). PLS may originate from the prostate or from other portions of the male genital tract. Although PLS could be associated with 'prostatitis', they should not be confused. The NIH-CPSI is considered the gold-standard for assessing PLS severity. Although previous studies investigated the impact of prostatitis, vesiculitis or epididymitis on semen parameters, correlations between their related symptoms and seminal or scrotal/transrectal colour-Doppler ultrasound (CDU) characteristics have not been carefully determined. And no previous study evaluated the CDU features of PLS in infertile men. This study was aimed at investigating possible associations among NIH-CPSI (total and subdomain) scores and PLS, with seminal, clinical and scrotal/transrectal CDU parameters in a cohort of males of infertile couples. PLS of 400 men (35.8 ± 7.2 years) with a suspected male factor were assessed by the NIH-CPSI. All patients underwent, during the same day, semen analysis, seminal plasma interleukin 8 (sIL-8, a marker of male genital tract inflammation), biochemical evaluation, urine/seminal cultures, scrotal/transrectal CDU. PLS was detected in 39 (9.8%) subjects. After adjusting for age, waist and total testosterone (TT), no association among NIH-CPSI (total or subdomain) scores or PLS and sperm parameters was observed. However, we found a positive association with current positive urine and/or seminal cultures, sIL-8 levels and CDU features suggestive of inflammation of the epididymis, seminal vesicles, prostate, but not of the testis. The aforementioned significant associations of PLS were further confirmed by comparing PLS patients with age-, waist- and TT-matched PLS-free patients (1 : 3 ratio). In conclusion, NIH

  1. Physiological aspects of the determination of comprehensive arterial inflows in the lower abdomen assessed by Doppler ultrasound

    PubMed Central

    2012-01-01

    Non-invasive measurement of splanchnic hemodynamics has been utilized in the clinical setting for diagnosis of gastro-intestinal disease, and for determining reserve blood flow (BF) distribution. However, previous studies that measured BF in a "single vessel with small size volume", such as the superior mesenteric and coeliac arteries, were concerned solely with the target organ in the gastrointestinal area, and therefore evaluation of alterations in these single arterial BFs under various states was sometimes limited to "small blood volumes", even though there was a relatively large change in flow. BF in the lower abdomen (BFAb) is potentially a useful indicator of the influence of comprehensive BF redistribution in cardiovascular and hepato-gastrointestinal disease, in the postprandial period, and in relation to physical exercise. BFAb can be determined theoretically using Doppler ultrasound by subtracting BF in the bilateral proximal femoral arteries (FAs) from BF in the upper abdominal aorta (Ao) above the coeliac trunk. Prior to acceptance of this method of determining a true BFAb value, it is necessary to obtain validated normal physiological data that represent the hemodynamic relationship between the three arteries. In determining BFAb, relative reliability was acceptably high (range in intra-class correlation coefficient: 0.85-0.97) for three arterial hemodynamic parameters (blood velocity, vessel diameter, and BF) in three repeated measurements obtained over three different days. Bland-Altman analysis of the three repeated measurements revealed that day-to-day physiological variation (potentially including measurement error) was within the acceptable minimum range (95% of confidence interval), calculated as the difference in hemodynamics between two measurements. Mean BF (ml/min) was 2951 ± 767 in Ao, 316 ± 97 in left FA, 313 ± 83 in right FA, and 2323 ± 703 in BFAb, which is in agreement with a previous study that measured the sum of BF in the major

  2. Optical biopsy of the prostate: can we TRUST (trans-rectal ultrasound-coupled spectral tomography)?

    NASA Astrophysics Data System (ADS)

    Piao, Daqing; Jiang, Zhen; Bartels, Kenneth E.; Holyoak, G. Reed; Ritchey, Jerry W.; Rock, Kendra; Ownby, Charlotte L.; Bunting, Charles F.; Slobodov, Gennady

    2011-03-01

    Needle-based core-biopsy to locate prostate cancer relies heavily upon trans-rectal ultrasound (TRUS) imaging guidance. Ultrasonographic findings of classic hypoechoic peripheral zone lesions have a low specificity of ~28%, a low positive predictive value of ~29%, and an overall accuracy of ~43%, in prostate cancer diagnosis. The prevalence of isoechoic or nearly invisible prostate cancers on ultrasonography ranges from 25 to 42%. As a result, TRUS is useful and convenient to direct the needle trajectory following a systematic biopsy sampling template rather than to target only the potentially malignant lesion for focal-biopsy. To address this deficiency in the first-line of prostate cancer imaging, a trans-rectal ultrasound-coupled spectral tomography (TRUST) approach is being developed to non-invasively resolve the likely optical signatures of prostate malignancy. The approach has evolved from using one NIR wavelength to two NIR bands, and recently to three bands of NIR spectrum information. The concept has been evaluated on one normal canine prostate and three dogs with implanted prostate tumor developed as a model. The initial results implementing TRUST on the canine prostate tumor model includes: (1) quantifying substantially increased total hemoglobin concentration over the time-course of imaging in a rapidly growing prostate tumor; (2) confirming hypoxia in a prostatic cystic lesion; and (3) imaging hypoxic changes of a necrotic prostate tumor. Despite these interesting results, intensive technologic development is necessary for translating the approach to benefiting clinical practice, wherein the ultimate utility is not possibly to eliminate needle-biopsy but to perform focal-biopsy that is only necessary to confirm the cancer, as well as to monitor and predict treatment responses.

  3. Can Doppler or contrast-enhanced ultrasound analysis add diagnostically important information about the nature of breast lesions?

    PubMed Central

    Stanzani, Daniela; Chala, Luciano F.; de Barros, Nestor; Cerri, Giovanni G.; Chammas, Maria Cristina

    2014-01-01

    OBJECTIVES: Despite evidence suggesting that Doppler ultrasonography can help to differentiate between benign and malignant breast lesions, it is rarely applied in clinical practice. The aim of this study was to determine whether certain vascular features of breast masses observed by duplex Doppler and color Doppler ultrasonography (before and/or after microbubble contrast injection) add information to the gray-scale analysis and support the Breast Imaging-Reporting and Data System (BI-RADS) classification. METHODS: Seventy solid lesions were prospectively evaluated with gray-scale ultrasonography, color Doppler ultrasonography, and contrast-enhanced ultrasonography. The morphological analysis and lesion vascularity were correlated with the histological results. RESULTS: Percutaneous core biopsies revealed that 25/70 (17.5%) lesions were malignant, while 45 were benign. Hypervascular lesions with tortuous and central vessels, a resistive index (RI)≥0.73 before contrast injection, and an RI≥0.75 after contrast injection were significantly predictive of malignancy (p<0.001). CONCLUSION: The combination of gray-scale ultrasonography data with unenhanced or enhanced duplex Doppler and color Doppler US data can provide diagnostically useful information. These techniques can be easily implemented because Doppler devices are already present in most health centers. PMID:24519198

  4. Doppler ultrasound in the evaluation of cirrhotic patients: the prevalence of intrahepatic arteriovenous shunting, and implications for diagnosis of hepatocellular carcinoma.

    PubMed

    Taylor, C R; Garcia-Tsao, G; Henson, B; Case, C Q; Taylor, K J

    1997-01-01

    To establish the prevalence and significance of Doppler-detected hepatic arteriovenous shunting (AVS) in patients with compensated cirrhosis, 115 patients (mean age 55.4 +/- 12.47 SD y) were prospectively screened using real-time ultrasound with pulsed Doppler at 2.5 MHz to detect focal liver lesions and quantify AVS. Focal masses were biopsied and correlated with the US findings. All other patients had clinical follow-up and imaging for at least 12 months. AVS occurred in 28 of 115 (24.3%), and in 18 of 20 proven malignancies (90%) including 11 of 13 cases of hepatocellular carcinoma (85%). However, 9 of 28 (32%) AVS (mean Doppler shift 2.73 +/- 1.51 [SD] kHz [range 0.6-5.41 kHz], n = 9) were in regions of fatty infiltration (4) or isolated (5), unassociated with malignancy. At a prevalence of 17.9% malignancy (11.3% due to hepatocellular carcinoma), specificity for malignancy increased with shunt velocity, from 76% (for mass alone), to 94.8% for mass with AVS, 96.8% for a mass with AVS of 1.75-2.4 kHz, and 100% for a mass with AVS > 2.4 kHz. Doppler US is useful in characterizing liver lesions in cirrhotic patients: the majority of malignant hepatic lesions are associated with AVS and specificity for malignancy increases with shunt velocity. However, isolated AVS or AVS associated with focal fat may be detected in 7.8% of compensated cirrhotics.

  5. Diagnostic performance of axial-strain sonoelastography in confirming clinically diagnosed Achilles tendinopathy: comparison with B-mode ultrasound and color Doppler imaging.

    PubMed

    Ooi, Chin Chin; Schneider, Michal Elisabeth; Malliaras, Peter; Chadwick, Martine; Connell, David Alister

    2015-01-01

    This primary aim of this study was to evaluate the diagnostic performance of axial-strain sonoelastography (ASE), B-mode ultrasound (US) and color Doppler US in confirming clinically symptomatic Achilles tendinopathy. The secondary aim was to establish the relationship between the strain ratio during sonoelastography and Victorian Institute of Sport Assessment-Achilles (VISA-A) scores. The VISA-A questionnaire is a validated clinical rating scale that evaluates the symptoms and dysfunction of the Achilles tendon. One hundred twenty Achilles tendons of 120 consecutively registered patients with clinical symptoms of Achilles tendinopathy and another 120 gender- and age-matched, asymptomatic Achilles tendons of 120 healthy volunteers were assessed with B-mode US, ASE and color Doppler US. Symptomatic patients had significantly higher strain ratio scores and softer Achilles tendon properties compared with controls (p < 0.001). The strain ratio was moderately correlated with VISA-A scores (r = -0.62, p < 0.001). The diagnostic accuracy of B-mode US, ASE and color Doppler US in confirming clinically symptomatic Achilles tendinopathy was 94.7%, 97.8% and 82.5% respectively. There was excellent correlation between the clinical reference standard and the grade of tendon quality on ASE (κ = 0.91, p < 0.05), compared with B-mode US (κ = 0.74, p < 0.05) and color Doppler imaging (κ = 0.49, p < 0.05). ASE is an accurate clinical tool in the evaluation of Achilles tendinopathy, with results comparable to those of B-mode US and excellent correlation with clinical findings. The strain ratio may offer promise as a supplementary tool for the objective evaluation of Achilles tendon properties.

  6. Comprehensive approach to breast cancer detection using light: photon localization by ultrasound modulation and tissue characterization by spectral discrimination

    NASA Astrophysics Data System (ADS)

    Marks, Fay A.; Tomlinson, Harold W.; Brooksby, Glen W.

    1993-09-01

    A new technique called Ultrasound Tagging of Light (UTL) for imaging breast tissue is described. In this approach, photon localization in turbid tissue is achieved by cross- modulating a laser beam with focussed, pulsed ultrasound. Light which passes through the ultrasound focal spot is `tagged' with the frequency of the ultrasound pulse. The experimental system uses an Argon-Ion laser, a single PIN photodetector, and a 1 MHz fixed-focus pulsed ultrasound transducer. The utility of UTL as a photon localization technique in scattering media is examined using tissue phantoms consisting of gelatin and intralipid. In a separate study, in vivo optical reflectance spectrophotometry was performed on human breast tumors implanted intramuscularly and subcutaneously in nineteen nude mice. The validity of applying a quadruple wavelength breast cancer discrimination metric (developed using breast biopsy specimens) to the in vivo condition was tested. A scatter diagram for the in vivo model tumors based on this metric is presented using as the `normal' controls the hands and fingers of volunteers. Tumors at different growth stages were studied; these tumors ranged in size from a few millimeters to two centimeters. It is expected that when coupled with a suitable photon localization technique like UTL, spectral discrimination methods like this one will prove useful in the detection of breast cancer by non-ionizing means.

  7. Ultrasound

    MedlinePlus

    ... called multiples) To screen for birth defects, like spina bifida or heart defects . Screening means seeing if your ... example, if the ultrasound shows your baby has spina bifida, she may be treated in the womb before ...

  8. Ultrasound

    MedlinePlus Videos and Cool Tools

    ... baby's development in the uterus. Ultrasound uses inaudible sound waves to produce a two-dimensional image of the baby while inside the mother's uterus. The sound waves bounce off solid structures in the body ...

  9. Ultrawideband coherent noise lidar range-Doppler imaging and signal processing by use of spatial-spectral holography in inhomogeneously broadened absorbers.

    PubMed

    Li, Youzhi; Hoskins, Alan; Schlottau, Friso; Wagner, Kelvin H; Embry, Carl; Babbitt, William Randall

    2006-09-01

    We introduce a new approach to coherent lidar range-Doppler sensing by utilizing random-noise illuminating waveforms and a quantum-optical, parallel sensor based on spatial-spectral holography (SSH) in a cryogenically cooled inhomogeneously broadened absorber (IBA) crystal. Interference between a reference signal and the lidar return in the spectrally selective absorption band of the IBA is used to sense the lidar returns and perform the front-end range-correlation signal processing. Modulating the reference by an array of Doppler compensating frequency shifts enables multichannel Doppler filtering. This SSH sensor performs much of the postdetection signal processing, increases the lidar system sensitivity through range-correlation gain before detection, and is capable of not only Doppler processing but also parallel multibeam reception using the high-spatial resolution of the IBA crystals. This approach permits the use of ultrawideband, high-power, random-noise, cw lasers as ranging waveforms in lidar systems instead of highly stabilized, injection-seeded, and amplified pulsed or modulated laser sources as required by most conventional coherent lidar systems. The capabilities of the IBA media for many tens of gigahertz bandwidth and resolution in the 30-300 kHz regime, while using either a pseudo-noise-coded waveform or just a high-power, noisy laser with a broad linewidth (e.g., a truly random noise lidar) may enable a new generation of improved lidar sensors and processors. Preliminary experimental demonstrations of lidar ranging and simulation on range-Doppler processing are presented.

  10. Medical Ultrasound Imaging.

    ERIC Educational Resources Information Center

    Hughes, Stephen

    2001-01-01

    Explains the basic principles of ultrasound using everyday physics. Topics include the generation of ultrasound, basic interactions with material, and the measurement of blood flow using the Doppler effect. (Author/MM)

  11. Cranial Ultrasound/Head Ultrasound

    MedlinePlus

    ... sickle cell disease. It is also used to measure conditions affecting blood flow to and within the brain, such as: Stenosis : ... saved. Doppler ultrasound, a special application of ultrasound, measures ... represent the flow of blood through the blood vessels. top of ...

  12. Ultrasound annual, 1986

    SciTech Connect

    Sanders, R.C.; Hill, M.C.

    1986-01-01

    This book provides an analyses of developments in the field of diagnostic ultrasound. Endoscopic ultrasound and ultrasound-guided aspiration of ovarian follicles for in vitro fertilization are addressed. The use of Doppler ultrasound to measure blood flow in obstetrics is also examined.

  13. Spectral radiative transfer for the 4.0- to 5.0-micron bands of CO and CO2 with mild vibrational relaxation and Doppler shift

    NASA Astrophysics Data System (ADS)

    Limbaugh, C. C.; Hiers, R. S., III; Phillips, W. J.

    1990-06-01

    This paper presents representative results for line-by-line spectral calculations of the 4.3-micron band of CO2 and the 5.0-micron band of CO in a nozzle-constrained, vibrationally relaxing combustion flow. The effects of property gradients are included, with special emphasis on the effects of the frequency shift of the radiation and absorption due to the component of velocity along the line of sight. Broadband spectra resulting from the convolution of the line-by-line results with a broadband filter are examined. It is shown that the effect of the Doppler shift is to broaden the individual spectral features with an attendant increase in the emitted radiation. Spectral detail is lost because of the broadening, and the greatest effect on the magnitude of the emission is for those lines which are optically thick.

  14. Semiquantitative Evaluation of Extrasynovial Soft Tissue Inflammation in the Shoulders of Patients with Polymyalgia Rheumatica and Elderly-Onset Rheumatoid Arthritis by Power Doppler Ultrasound.

    PubMed

    Suzuki, Takeshi; Yoshida, Ryochi; Okamoto, Akiko; Seri, Yu

    2017-01-01

    Objectives. To develop a scoring system for evaluating the extrasynovial soft tissue inflammation of the shoulders in patients with polymyalgia rheumatica (PMR) and elderly-onset rheumatoid arthritis with PMR-like onset (pm-EORA) using ultrasound. Methods. We analyzed stored power Doppler (PD) images obtained by the pretreatment examination of 15 PMR patients and 15 pm-EORA patients. A semiquantitative scoring system for evaluating the severity of PD signals adjacent to the anterior aspect of the subscapularis tendon was designed. Results. A four-point scale scoring for the hyperemia on the subscapularis tendon was proposed as follows in brief: 0 = absent or minimal flow, 1 = single vessel dots or short linear-shape signals, 2 = long linear-shape signals or short zone-shape signals, or 3 = long zone-shape signals. This scoring system showed good intra- and interobserver reliability and good correlation to quantitative pixel-counting evaluation. By using it, we demonstrated that inflammation in PMR is dominantly localized in extrasynovial soft tissue as compared with pm-EORA. Conclusions. We proposed a reliable semiquantitative scoring system using ultrasound for the evaluation of extrasynovial soft tissue inflammation of the shoulders in patients with both PMR and pm-EORA. This system is simple to use and can be utilized in future investigations.

  15. Semiquantitative Evaluation of Extrasynovial Soft Tissue Inflammation in the Shoulders of Patients with Polymyalgia Rheumatica and Elderly-Onset Rheumatoid Arthritis by Power Doppler Ultrasound

    PubMed Central

    Yoshida, Ryochi; Okamoto, Akiko; Seri, Yu

    2017-01-01

    Objectives. To develop a scoring system for evaluating the extrasynovial soft tissue inflammation of the shoulders in patients with polymyalgia rheumatica (PMR) and elderly-onset rheumatoid arthritis with PMR-like onset (pm-EORA) using ultrasound. Methods. We analyzed stored power Doppler (PD) images obtained by the pretreatment examination of 15 PMR patients and 15 pm-EORA patients. A semiquantitative scoring system for evaluating the severity of PD signals adjacent to the anterior aspect of the subscapularis tendon was designed. Results. A four-point scale scoring for the hyperemia on the subscapularis tendon was proposed as follows in brief: 0 = absent or minimal flow, 1 = single vessel dots or short linear-shape signals, 2 = long linear-shape signals or short zone-shape signals, or 3 = long zone-shape signals. This scoring system showed good intra- and interobserver reliability and good correlation to quantitative pixel-counting evaluation. By using it, we demonstrated that inflammation in PMR is dominantly localized in extrasynovial soft tissue as compared with pm-EORA. Conclusions. We proposed a reliable semiquantitative scoring system using ultrasound for the evaluation of extrasynovial soft tissue inflammation of the shoulders in patients with both PMR and pm-EORA. This system is simple to use and can be utilized in future investigations. PMID:28293635

  16. Effects of Isoflurane on Coronary Blood Flow Velocity in Young, Old, and ApoE−/− Mice Measured by Doppler Ultrasound

    PubMed Central

    Hartley, Craig J.; Reddy, Anilkumar K.; Madala, Sridhar; Michael, Lloyd H.; Entman, Mark L.; Taffet, George E.

    2007-01-01

    The commonly used anesthetic agent, isoflurane (ISO), is a potent coronary vasodilator which could potentially be used in the assessment of coronary reserve, but its effects on coronary blood flow in mice are unknown. Coronary reserve is reduced by age, coronary artery disease, and other cardiac pathologies in man, and some of these conditions can now be modeled in mice. Accordingly, we used Doppler ultrasound to measure coronary flow velocity in mice anesthetized at low (1%) and at high (2.5%) levels of ISO to generate baseline (B) and elevated hyperemic (H) coronary flows respectively. A 20 MHz Doppler probe was mounted in a micromanipulator and pointed transthoracically toward the origin of the left main coronary arteries of 10 6-wk (Y), 10 2-yr (O), and 20 2-yr apolipoprotein-E null (ApoE−/−) atherosclerotic (A) mice. In each mouse we measured (B) and (H) peak diastolic velocities. B was 35.4 +/− 1.4 cm/s (Y), 24.8 +/− 1.6 (O), and 51.7 +/− 6.4 (A); H was 83.5 +/− 1.3 (Y), 86.5 +/− 1.9 (O), and 120 +/− 16.9 (A); and H/B was 2.4 +/− 0.1 (Y), 3.6 +/− 0.2 (O), and 2.5 +/− 0.2 (A). The differences in baseline velocities and H/B between O and Y and between A and O were significant (P < 0.01), while the differences in hyperemic velocities were not (P > 0.05). H/B was higher in old mice due to decreased baseline flow rather than increased hyperemic flow velocity. In contrast ApoE−/− mice have increased baseline and hyperemic velocities perhaps due to coronary lesions. The differences in baseline velocities between young and old mice could be due to age-related changes in basal metabolism or to differential sensitivity to isoflurane. We conclude that Doppler ultrasound combined with coronary vasodilation via isoflurane could provide a convenient and noninvasive method to estimate coronary reserve in mice, but also that care must be taken when assessing coronary flow in mice under isoflurane anesthesia because of its potent coronary vasodilator

  17. Advanced Spectral Analysis Methods for Quantification of Coherent Ultrasound Scattering: Applications in the Breast

    NASA Astrophysics Data System (ADS)

    Rosado-Mendez, Ivan M.

    The goal of this dissertation was to improve the diagnostic value of parametric images generated from Quantitative Ultrasound (QUS) methods based on the power spectral density (PSD) of radiofrequency echo signals. This was achieved by testing for local adherence to conventional QUS assumptions that echo signals originate from incoherent scattering, and that signals are stationary over PSD estimation windows. For this purpose, we designed a novel algorithm that empirically evaluates the statistical significance of coherent-scattering signatures in the echo signals. Signatures are quantified through a set of optimized metrics describing the stationary or non-stationary features of the echo signals. We compared Nakagami-model based metrics and model-free metrics of the statistics of the echo signal amplitude for analyzing stationary features. For non-stationary features, we advanced the use of the echo-signal generalized spectrum by comparing single- and multi-taper estimators of this spectrum to the time-domain singular spectrum analysis method. Tests of statistical significance were done through empirical comparisons with values of the same metrics estimated from a uniform reference material exhibiting incoherent scattering. The metrics that quantify these features were selected after simulation- and phantom-based optimizations centered on the task of creating parametric images, where tradeoffs must be made between spatial resolution and detection performance. The connection of the analyses of the stationary and the non-stationary features provided a way to estimate descriptors of the tissue organization scales below and above the resolution limit imposed by the size of the acoustic pulse. A preliminary application of the developed algorithm was done on echo data from human breast lesions scanned in vivo. Results supported the idea of a more homogeneously random distribution of subresolution scatterers within invasive ductal carcinomas than within fibroadenomas

  18. Depth-dependent displacement sensitivity analysis and the influence of Doppler angle for quantitative assessment of mechanical properties using phase-sensitive spectral domain optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Lynch, Gillian; Subhash, Hrebesh; Alexandrov, Sergey; Leahy, Martin

    2016-03-01

    Optical coherence elastography (OCE) asesses the mechanical properties of samples by applying a mechanical stimulation and detecting the resulting sample displacement using optical coherence tomography (OCT). OCE methods which utilise the phase of the OCT signal offer the potential to detect displacements on the sub-nanometre scale. However, the displacement sensitivity achieveable is directly related to the signal-to-noise ratio and phase stability of the underlying OCT system. Furthermore, the estimation of Doppler angle is imperative in accurately measuring the sample displacement. This work evaluates the contributions of each of these parameters for quantitative assessment of mechanical properties using phase-sensitive spectral domain OCT.

  19. Quantitative Doppler measures in coiled vessels: investigation on excised umbilical veins.

    PubMed

    Guiot, C; Roatta, S; Piccoli, E; Saccomandi, F; Todros, T

    1999-11-01

    Quantitative assessment of umbilical venous blood velocity with Doppler ultrasound (US) must cope with the coiled structure of the vein inside the cord. Both an experimental and a theoretical approach showed remarkable variations in the insonation angle when the probe was moved along the vein, provided the inclination between the Doppler probe and the cord was kept constant. Inaccurate signal processing, stochastic variability and flow disturbances could, however, mask the influence of the geometry. The above hypotheses were assessed by investigating five cords in vitro a few hours after delivery from normal pregnancies at term. The Doppler signal was sampled at different sites along each cord and the mean Doppler shift estimated by FFT spectral analysis, both directly and through the noise rejection D'Alessio's algorithm, which proved effective in improving the Doppler shift estimate in condition of low signal-to-noise ratio (SNR).

  20. Contrast M-mode power Doppler ultrasound in the detection of right-to-left shunts: utility of submandibular internal carotid artery recording.

    PubMed

    Topçuoglu, M A; Palacios, I F; Buonanno, F S

    2003-10-01

    Cardiac right-to-left shunts (RLSs) can be detected by echocardiography and transcranial Doppler ultrasound (TCD). In patients without adequate transtemporal bone windows, results may be obtained by insonating extracranial arteries; however, the sensitivity and practicality of this approach is unknown. In 34 patients evaluated with echocardiography for RLSs, 73 studies were performed with unilateral, simultaneous contrast TCD (cTCD) of the middle cerebral artery (MCA) and anterior cerebral artery (ACA) and submandibular power M-mode Doppler (PMD) ultrasound of the extracranial internal carotid artery (ecICA). The number of microbubble (MB) signals and their times of first appearance were determined. RLS volume was graded on 6 levels (I = trace, II = small, III = medium, IVa = large, IVb = shower, IVc = curtain) and compared between MCA and ecICA recordings. In 2 of 24 cTCD studies in 15 patients without evidence of RLSs on single-gated MCA monitoring, low-volume RLSs (grades I and II) were detected via ecICA insonation; in both, MB signatures were tracked in the ecICA, passing into the ipsilateral ACA. In 40 of 49 studies (26 patients) in which RLSs were demonstrated with single-gated MCA monitoring, more MBs were detected in the ecICA than the MCA, with either single-gated or M-mode images, with increases of 76.9% and 66.1%, respectively (P = .027). Compared to single-gated studies, M-mode technology detected nonsignificant increases in MB number in both the MCA and the ecICA (by 20.2% and 14.0%, respectively). Contrast PMD with cervical ICA recording is at least as sensitive and specific as the traditional MCA method in detecting RLSs; furthermore, this method seems to be more sensitive for low-volume RLSs (grades I-III) because of air MB decay (9.2%) and entry into the ipsilateral ACA (34.2%). This is in concordance with the increase of detected RLS grades observed in 32.7% of patients with echocardiography-documented RLSs. The authors therefore suggest the

  1. Different optical spectral characteristics in a necrotic transmissible venereal tumor and a cystic lesion in the same canine prostate observed by triple-band trans-rectal optical tomography under trans-rectal ultrasound guidance

    NASA Astrophysics Data System (ADS)

    Jiang, Zhen; Holyoak, G. Reed; Ritchey, Jerry W.; Bartels, Kenneth E.; Rock, Kendra; Ownby, Charlotte L.; Slobodov, Gennady; Bunting, Charles F.; Piao, Daqing

    2011-03-01

    Different optical spectral characteristics were observed in a necrotic transmissible venereal tumor (TVT) and a cystic lesion in the same canine prostate by triple-wavelength trans-rectal optical tomography under trans-rectal ultrasound (TRUS) guidance. The NIR imager acquiring at 705nm, 785nm and 808nm was used to quantify both the total hemoglobin concentration (HbT) and oxygen saturation (StO2) in the prostate. The TVT tumor in the canine prostate as a model of prostate cancer was induced in a 7-year old, 27 kg dog. A 2 mL suspension of 2.5x106 cells/mL of homogenized TVT cells recovered from an in vivo subcutaneously propagated TVT tumor in an NOD/SCID mouse were injected in the cranial aspect of the right lobe of the canine prostate. The left lobe of the prostate had a cystic lesion present before TVT inoculation. After the TVT homogenate injection, the prostate was monitored weekly over a 9-week period, using trans-rectal NIR and TRUS in grey-scale and Doppler. A TVT mass within the right lobe developed a necrotic center during the later stages of this study, as the mass presented with substantially increased [HbT] in the periphery, with an area of reduced StO2 less than the area of the mass itself shown on ultrasonography. Conversely, the cystic lesion presented with slightly increased [HbT] in the periphery of the lesion shown on ultrasound with oxygen-reduction inside and in the periphery of the lesion. There was no detectable change of blood flow on Doppler US in the periphery of the cystic lesion. The slightly increased [HbT] in the periphery of the cystic lesion was correlated with intra-lesional hemorrhage upon histopathologic examination.

  2. Estimation of Measurement Characteristics of Ultrasound Fetal Heart Rate Monitor

    NASA Astrophysics Data System (ADS)

    Noguchi, Yasuaki; Mamune, Hideyuki; Sugimoto, Suguru; Yoshida, Atsushi; Sasa, Hidenori; Kobayashi, Hisaaki; Kobayashi, Mitsunao

    1995-05-01

    Ultrasound fetal heart rate monitoring is very useful to determine the status of the fetus because it is noninvasive. In order to ensure the accuracy of the fetal heart rate (FHR) obtained from the ultrasound Doppler data, we measure the fetal electrocardiogram (ECG) directly and obtain the Doppler data simultaneously. The FHR differences of the Doppler data from the direct ECG data are concentrated at 0 bpm (beats per minute), and are practically symmetrical. The distribution is found to be very close to the Student's t distribution by the test of goodness of fit with the chi-square test. The spectral density of the FHR differences shows the white noise spectrum without any dominant peaks. Furthermore, the f-n (n>1) fluctuation is observed both with the ultrasound Doppler FHR and with the direct ECG FHR. Thus, it is confirmed that the FHR observation and observation of the f-n (n>1) fluctuation using the ultrasound Doppler FHR are as useful as the direct ECG.

  3. FETAL RENAL ARTERY IMPEDANCE AS ASESSED BY DOPPLER ULTRASOUND IN PREGNANCIES COMPLICATED BY INTRA-AMNIOTIC INFLAMMATION AND PRETERM BIRTH

    PubMed Central

    Azpurua, Humberto; Dulay, Antonette T.; Buhimschi, Irina A.; Bahtiyar, Mert O.; Funai, Edmund; Abdel-Razeq, Sonya S.; Luo, Guoyang; Bhandari, Vineet; Copel, Joshua A.; Buhimschi, Catalin S.

    2013-01-01

    OBJECTIVE To evaluate the fetal renal artery impedance in the context of inflammation-associated preterm birth (PTB). STUDY DESIGN We conducted a prospective Doppler assessment of the fetal renal artery impedance in 70 singleton fetuses. The study group consisted of 56 premature fetuses (28.1 [25.3–30.6] weeks at enrollment). Gestational age (GA) reference ranges were generated based on fetuses with uncomplicated pregnancies (n=14). Doppler studies included renal artery pulsatility index (PI), resistance index (RI), systolic/diastolic (S/D) ratio and presence-or-absence of end-diastolic blood flow. We assessed amniotic fluid (AF) inflammation by proteomic profiling (SELDI-TOF). Data were interpreted in relationship to amniotic fluid index (AFI), cord blood interleukin-6 (IL-6) and erythropoietin (EPO) levels. The cardiovascular and metabolic profiles of the neonates were investigated in the first 24 hours of life. RESULTS Fetuses delivered by mothers with intra-amniotic inflammation had higher cord blood IL-6 but not EPO levels. Fetal inflammation did not affect either renal artery PI,RI,S/D ratio or end-diastolic blood flow. Neonates delivered in the context of intraamniotic inflammation had higher serum blood urea nitrogen levels, which correlated significantly with AF IL-6 levels. The renal artery RI and SD ratio were inversely correlated with the AFI independent of GA, cord blood IL-6 and status of the membranes. CONCLUSION The fetus is capable of sustaining normal renal artery impedance despite inflammation. Resistance in the renal vascular bed affects urine output independent of inflammation. PMID:19185102

  4. Changes in the central and peripheral circulatory system in response to the cold: own studies using impedance plethysmography and Doppler ultrasound.

    PubMed

    Łastowiecka-Moras, Elżbieta; Kozyra-Pydyś, Eliza

    2016-12-01

    The aim of the study was to determine the cardiovascular response to continuous (4 °C for 60 min) and intermittent (10 min at 4 °C and 10 min at room temperature alternately) exposure to the cold in 30 healthy young men. The subjects were equipped with a set of identical clothing (insulation 2.1 clo) and during the stay in the chamber and outside performed the same activities, i.e., walking on a treadmill at a speed of 0.5 km/h. The tests included assessing the central circulatory system using the Holter system and assessing the peripheral circulatory system using impedance plethysmography and Doppler ultrasound. The analysis of the parameters that describe the central and peripheral circulation poses a difficulty in determining which variant of exposure constitutes a greater load on the circulatory system. It should be noted that even the conditions used in the study may cause adverse effects in the cardiovascular system.

  5. Internal iliac and uterine arteries Doppler ultrasound in the assessment of normotensive and chronic hypertensive pregnant women

    PubMed Central

    Guedes-Martins, L.; Cunha, A.; Saraiva, J.; Gaio, R.; Macedo, F.; Almeida, H.

    2014-01-01

    The objective of this work was to compare Doppler flows pulsatility index (PI) and resistance indexes (RI) of uterine and internal iliac arteries during pregnancy in low risk women and in those with stage-1 essential hypertension. From January 2010 and December 2012, a longitudinal and prospective study was carried out in 103 singleton uneventful pregnancies (72 low-risk pregnancies and 31 with stage 1 essential hypertension)at the 1st, 2nd and 3rd trimesters. Multiple linear regression models, fitted using generalized least squares and whose errors were allowed to be correlated and/or have unequal variances, were employed; a model for the relative differences of both arteries impedance was utilized. In both groups, uterine artery PI and RI exhibited a gestational age related decreasing trend whereas internal iliac artery PI and RI increased. The model testing the hemodynamic adaptation in women with and without hypertension showed similar trend. Irrespective of blood pressure conditions, the internal iliac artery resistance pattern contrasts with the capacitance pattern of its immediate pelvic division, suggesting a pregnancy-related regulatory mechanism in the pelvic circulation. PMID:24445576

  6. Time Course of Isoflurane-Induced Vasodilation: A Doppler Ultrasound Study of the Left Coronary Artery in Mice.

    PubMed

    Lenzarini, Francesca; Di Lascio, Nicole; Stea, Francesco; Kusmic, Claudia; Faita, Francesco

    2016-04-01

    Isoflurane is widely used as vasodilator in studies of coronary flow reserve (CFR) in small animals, but the protocols have not been standardized. This study assessed the time course of the increase in isoflurane-induced flow in the mouse coronary artery by pulsed-wave Doppler measurements at 1% isoflurane concentration maintained for 6 min and then increased to 2.5% for 30 min. Velocity-time integral and velocity peak values were best fitted by the sigmoid model, which allowed derivation of the mean time (Tt90 = 14 min) of high-isoflurane needed to reach 90% of the hyperemic plateau value. In subsequent experiments, CFR was measured at 4 min (mean time of literature data) and 14 min of hyperemic response. The 4-min CFR was significantly lower than the 14 -min CFR, and the Bland-Altman plot revealed significant bias of the 4-min CFR against the 14-min CFR. This result suggests that measurements of flow velocity at times shorter than 14 min may be inappropriate for expressing the effective value of CFR.

  7. Stroke and conversion to high risk in children screened with transcranial Doppler ultrasound during the STOP study.

    PubMed

    Adams, Robert J; Brambilla, Donald J; Granger, Suzanne; Gallagher, Dianne; Vichinsky, Elliott; Abboud, Miguel R; Pegelow, Charles H; Woods, Gerald; Rohde, Elizabeth M; Nichols, Fenwick T; Jones, Anne; Luden, Judith P; Bowman, Latonya; Hagner, Susan; Morales, Knashawn H; Roach, E Steve

    2004-05-15

    The Stroke Prevention Trial in Sickle Cell Anemia (STOP) was a randomized multicenter controlled trial comparing prophylactic blood transfusion with standard care in sickle cell anemia (SCA) children aged 2 to 16 years selected for high stroke risk by transcranial Doppler (TCD). More than 2000 children were screened with TCD to identify the 130 high-risk children who entered the randomized trial. A total of 5613 TCD studies from 2324 children were evaluated. We also collected information on stroke. We describe the changes in TCD with repeated testing and report the outcome without transfusion in the STOP screened cohort. Risk of stroke was higher with abnormal TCD than with normal or conditional TCD (P <.001) or inadequate TCD (P =.002), and risk with conditional TCD was higher than with normal TCD (P <.001). Repeated TCD in 1215 children showed that the condition of 9.4% of children became abnormal during observation. Younger patients and those with higher initial flow velocities were most likely to convert to abnormal TCDs. Screening in STOP confirmed the predictive value of TCD for stroke. Substantial differences in the probability of conversion to abnormal TCD were observed, with younger children and those with higher velocity more likely to have an abnormal TCD with rescreening.

  8. Reducing registration error in cross-beam vector doppler imaging with position sensor.

    PubMed

    Xu, Canxing; Beach, Kirk W; Leotta, Daniel; Stuzman, Edward; Kim, Yongmin

    2009-01-01

    Various vector Doppler methods have been proposed in the last several decades to overcome the Doppler angle dependency in both conventional spectral Doppler and color Doppler by measuring both the speed and direction of blood flow. However, they have not been adopted for routine use because most of them require specialized hardware, which is not available in commercial ultrasound systems. An alternative approach (cross-beam method) that uses color Doppler images obtained from different steered beam angles is more feasible, but there is error in registering multiple color Doppler images because they are not acquired simultaneously. To alleviate this problem, we have evaluated a cross-beam vector Doppler system that registers spatially with a position sensor two color Doppler images from two different angles and temporally with ECG synchronization. The registration error was reduced to an average of 0.92 mm from 2.49 mm in 9 human subjects. Vector Doppler carotid artery images of a healthy subject and a patient with atherosclerotic plaques are also presented.

  9. Comparison of Very High-Frequency Ultrasound and Spectral-Domain Optical Coherence Tomography Corneal and Epithelial Thickness Maps

    PubMed Central

    Urs, Raksha; Lloyd, Harriet O.; Reinstein, Dan Z.; Silverman, Ronald H.

    2015-01-01

    Purpose To compare measurements of corneal thickness (CT) and epithelial thickness (ET) in maps obtained by the RTVue spectral domain optical coherence tomography (SD-OCT) system with those obtained from the Artemis 2 immersion arc-scanning very high-frequency ultrasound system. Setting Department of Ophthalmology of the Columbia University Medical Center Design A method-comparison study design to examine the agreement between two systems for measurement and mapping of CT and ET. Methods Both eyes of 12 normal volunteers were scanned with RTVue followed by Artemis and then by repeated RTVue. For each map, the minimum CT and mean values of CT and ET in the 3 mm radius zone and in 0.5 mm-wide concentric annuli of up to 3 mm radius around the corneal vertex were determined. Results The CT values from both devices were highly correlated and in the 3-mm radius zone (R>0.96) they were not statistically significantly different. There was no statistically significant change in ET or CT in RTVue measurements made before versus after immersion ultrasound. While highly correlated (R>0.76), RTVue ET values were systematically thinner (1.7 ± 2.1 µm) than Artemis 2 measurements (p<0.01) in the 3 mm radius zone. Conclusions Artemis and RTVue CT measurements in the 3 mm radius zone are equivalent in normal eyes. While correlated, Artemis ET measurements were systemically thicker than RTVue values. PMID:26948783

  10. Spectral Analysis of Vibrational Harmonic Motion by use of a Continuous-Wave CO2 Doppler Lidar

    NASA Technical Reports Server (NTRS)

    Jarzembski, Maurice A.; Srivastava, Vandana

    1999-01-01

    Vibrational motion of a harmonic oscillator was investigated using a focused continuous wave CO2 Doppler lidar at 9.1 microns wavelength. A continuum of frequencies along with many discrete, equally spaced, resonant frequency modes was observed. The frequency modes are similar in structure to the oscillatory longitudinal modes of a laser cavity and arise because of interference of the natural resonant frequency of the oscillator with specific frequencies within the continuum. The spectra revealed departures from linear motion for vigorous vibrations of the oscillator. Each consecutive resonant frequency mode occurred for a movement of the oscillator much less than the wavelength of incident lidar radiation.

  11. Monitoring of drug and stimulation induced cerebral blood flow velocity changes in rat sensory cortex using spectral domain Doppler optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Wang, Chuan; Yang, Yong; Ding, Zhihua; Meng, Jie; Wang, Kai; Yang, Wenwei; Xu, Ying

    2011-04-01

    Doppler optical coherence tomography (DOCT) provides a novel method to measure blood flow velocity in vessels with diameter at micrometer scale. In this study, a developed spectral domain DOCT system is applied to monitor cerebral blood flow velocity changes in a rat. An animal model with a cranial window is used, and by application of a drug, light, and electric stimulations, changes in blood flow velocity of the pial artery in sensory cortex are measured in real time. The results show significant differences in blood flow velocity before and after drug administration or light and electric stimulations, demonstrating the feasibility of DOCT in cerebral microcirculation study. Given its noninvasive nature, high spatial resolution, high velocity sensitivity, and high imaging speed, DOCT shows great promise in brain research by imaging blood flow changes at micrometer scale vessels, which helps to understand the pathogenesis of cerebral diseases and neurodegenerative diseases.

  12. Ultrasound-guided spectral photoacoustic imaging of hemoglobin oxygenation during development

    PubMed Central

    Bayer, Carolyn L.; Wlodarczyk, Bogdan J.; Finnell, Richard H.; Emelianov, Stanislav Y.

    2017-01-01

    Few technologies are capable of imaging in vivo function during development. In this study, we have implemented spectral photoacoustic imaging to estimate tissue oxygenation longitudinally in pregnant mice. We used the spectral photoacoustic signal to estimate hemoglobin oxygen saturation within intact, in vivo mouse concepti from developmental day (E) 8.5 to E16.5—a first step towards functional imaging of the maternal-fetal environment. Future work will apply these methods to compare longitudinal functional changes during normal vs abnormal development of embryos, fetuses, and placentas. PMID:28270982

  13. Perfusion imaging with non-contrast ultrasound

    NASA Astrophysics Data System (ADS)

    Tierney, Jaime E.; Dumont, Douglas M.; Byram, Brett C.

    2016-04-01

    A Doppler ultrasound clutter filter that enables estimation of low velocity blood flow could considerably improve ultrasound as a tool for clinical diagnosis and monitoring, including for the evaluation of vascular diseases and tumor perfusion. Conventional Doppler ultrasound is currently used for visualizing and estimating blood flow. However, conventional Doppler is limited by frame rate and tissue clutter caused by involuntary movement of the patient or sonographer. Spectral broadening of the clutter due to tissue motion limits ultrasound's ability to detect blood flow less than about 5mm/s at an 8MHz center frequency. We propose a clutter filtering technique that may increase the sensitivity of Doppler measurements to at least as low as 0.41mm/s. The proposed filter uses an adaptive demodulation scheme that decreases the bandwidth of the clutter. To test the performance of the adaptive demodulation method at removing sonographer hand motion, six volunteer subjects acquired data from a basic quality assurance phantom. Additionally, to test initial in vivo feasibility, an arterial occlusion reactive hyperemia study was performed to assess the efficiency of the proposed filter at preserving signals from blood velocities 2mm/s or greater. The hand motion study resulted in initial average bandwidths of 577Hz (28.5mm/s), which were decreased to 7.28Hz (0.36mm/s) at -60 dB at 3cm using our approach. The in vivo power Doppler study resulted in 15.2dB and 0.15dB dynamic ranges between the lowest and highest blood flow time points for the proposed filter and conventional 50Hz high pass filter, respectively.

  14. Modeling solar oscillation power spectra. II. Parametric model of spectral lines observed in Doppler-velocity measurements

    SciTech Connect

    Vorontsov, Sergei V.; Jefferies, Stuart M. E-mail: stuartj@ifa.hawaii.edu

    2013-11-20

    We describe a global parametric model for the observed power spectra of solar oscillations of intermediate and low degree. A physically motivated parameterization is used as a substitute for a direct description of mode excitation and damping as these mechanisms remain poorly understood. The model is targeted at the accurate fitting of power spectra coming from Doppler-velocity measurements and uses an adaptive response function that accounts for both the vertical and horizontal components of the velocity field on the solar surface and for possible instrumental and observational distortions. The model is continuous in frequency, can easily be adapted to intensity measurements, and extends naturally to the analysis of high-frequency pseudomodes (interference peaks at frequencies above the atmospheric acoustic cutoff).

  15. Pulse subtraction Doppler

    NASA Astrophysics Data System (ADS)

    Mahue, Veronique; Mari, Jean Martial; Eckersley, Robert J.; Caro, Colin G.; Tang, Meng-Xing

    2010-01-01

    Recent advances have demonstrated the feasibility of molecular imaging using targeted microbubbles and ultrasound. One technical challenge is to selectively detect attached bubbles from those freely flowing bubbles and surrounding tissue. Pulse Inversion Doppler is an imaging technique enabling the selective detection of both static and moving ultrasound contrast agents: linear scatterers generate a single band Doppler spectrum, while non-linear scatterers generate a double band spectrum, one being uniquely correlated with the presence of contrast agents and non-linear tissue signals. We demonstrate that similar spectrums, and thus the same discrimination, can be obtained through a Doppler implementation of Pulse Subtraction. This is achieved by reconstructing a virtual echo using the echo generated from a short pulse transmission. Moreover by subtracting from this virtual echo the one generated from a longer pulse transmission, it is possible to fully suppress the echo from linear scatterers, while for non-linear scatterers, a signal will remain, allowing classical agent detection. Simulations of a single moving microbubble and a moving linear scatterer subject to these pulses show that when the virtual echo and the long pulse echo are used to perform pulsed Doppler, the power Doppler spectrum allows separation of linear and non-linear moving scattering. Similar results are obtained on experimental data acquired on a flow containing either microbubble contrast agents or linear blood mimicking fluid. This new Doppler method constitutes an alternative to Pulse Inversion Doppler and preliminary results suggest that similar dual band spectrums could be obtained by the combination of any non-linear detection technique with Doppler demodulation.

  16. Maximum-likelihood spectral estimation and adaptive filtering techniques with application to airborne Doppler weather radar. Thesis Technical Report No. 20

    NASA Technical Reports Server (NTRS)

    Lai, Jonathan Y.

    1994-01-01

    This dissertation focuses on the signal processing problems associated with the detection of hazardous windshears using airborne Doppler radar when weak weather returns are in the presence of strong clutter returns. In light of the frequent inadequacy of spectral-processing oriented clutter suppression methods, we model a clutter signal as multiple sinusoids plus Gaussian noise, and propose adaptive filtering approaches that better capture the temporal characteristics of the signal process. This idea leads to two research topics in signal processing: (1) signal modeling and parameter estimation, and (2) adaptive filtering in this particular signal environment. A high-resolution, low SNR threshold maximum likelihood (ML) frequency estimation and signal modeling algorithm is devised and proves capable of delineating both the spectral and temporal nature of the clutter return. Furthermore, the Least Mean Square (LMS) -based adaptive filter's performance for the proposed signal model is investigated, and promising simulation results have testified to its potential for clutter rejection leading to more accurate estimation of windspeed thus obtaining a better assessment of the windshear hazard.

  17. The pulse-pair algorithm as a robust estimator of turbulent weather spectral parameters using airborne pulse Doppler radar

    NASA Technical Reports Server (NTRS)

    Baxa, Ernest G., Jr.; Lee, Jonggil

    1991-01-01

    The pulse pair method for spectrum parameter estimation is commonly used in pulse Doppler weather radar signal processing since it is economical to implement and can be shown to be a maximum likelihood estimator. With the use of airborne weather radar for windshear detection, the turbulent weather and strong ground clutter return spectrum differs from that assumed in its derivation, so the performance robustness of the pulse pair technique must be understood. Here, the effect of radar system pulse to pulse phase jitter and signal spectrum skew on the pulse pair algorithm performance is discussed. Phase jitter effect may be significant when the weather return signal to clutter ratio is very low and clutter rejection filtering is attempted. The analysis can be used to develop design specifications for airborne radar system phase stability. It is also shown that the weather return spectrum skew can cause a significant bias in the pulse pair mean windspeed estimates, and that the poly pulse pair algorithm can reduce this bias. It is suggested that use of a spectrum mode estimator may be more appropriate in characterizing the windspeed within a radar range resolution cell for detection of hazardous windspeed gradients.

  18. General Ultrasound Imaging

    MedlinePlus Videos and Cool Tools

    ... of the reflected sound waves (called the Doppler effect). A computer collects and processes the sounds and ... standard diagnostic ultrasound , there are no known harmful effects on humans. top of page What are the ...

  19. Ultrasound pregnancy

    MedlinePlus

    Pregnancy sonogram; Obstetric ultrasonography; Obstetric sonogram; Ultrasound - pregnancy; IUGR - ultrasound; Intrauterine growth - ultrasound; Polyhydramnios - ultrasound; Oligohydramnios - ultrasound; ...

  20. Transvaginal ultrasound

    MedlinePlus

    ... Uterine bleeding - transvaginal ultrasound; Menstrual bleeding - transvaginal ultrasound; Infertility - transvaginal ultrasound; Ovarian - transvaginal ultrasound; Abscess - transvaginal ultrasound

  1. To assess the intimal thickness, flow velocities, and luminal diameter of carotid arteries using high-resolution B-mode ultrasound doppler imaging

    NASA Astrophysics Data System (ADS)

    Vemuru, Madhuri; Jabbar, Afzal; Chandra, Suman

    2004-04-01

    Carotid imaging is a Gold Standard test that provides useful information about the structure and functions of carotid arteries. Spectral imaging helps to evaluate the vessel and hemodynamic changes. High resolution B-mode imaging has emerged as one of the methods of choice for determining the anatomic extent of atherosclerosis and its progression and for assessing cardiovascular risks. The measurements made with Doppler correlate well with pathologic measurements. Recent prospective studies have clearly demonstrated that these measurements of carotid intimal thickness are potent predictors of Myocardial Infarction and Stroke. This method appears very attractive as it is non-invasive, extremely safe, well accepted by the patient and relatively inexpensive. It can be performed serially and has the advantage of visualizing the arterial wall in contrast to angiographic techniques which provide only an outline of the arterial lumen. Recently, there has been an interest in the clinical use of this technique in making difficult clinical decisions like deciding on preventive therapies. 30 subjects aged 21-60 years and 30 subjects aged 61-85 years of both sexes are selected after doing a baseline study to exclude Hypertension, Diabetes, Obesity and Hyperlipidemia. The carotid arteries were examined for intimal thickening, blood flow velocities and luminal diameter. With aging there is a narrowing of the carotid vessels and significant increase in intimal thickening with a consequent increase in the blood flow velocities. Inter-observer, intra-observer and instrument variations are seen and there is no significant change in the values when the distal flow pattern is considered for measurements. Aging produces major cardiovascular changes including decreased elasticity and compliance of great arteries leading to structural and functional alterations in heart and vessels. With aging there is increased intimal thickness and increased pulse wave velocity which is clearly

  2. Estimation of the blood Doppler frequency shift by a time-varying parametric approach.

    PubMed

    Girault, J M; Kouamé, D; Ouahabi, A; Patat, F

    2000-03-01

    Doppler ultrasound is widely used in medical applications to extract the blood Doppler flow velocity in the arteries via spectral analysis. The spectral analysis of non-stationary signals and particularly Doppler signals requires adequate tools that should present both good time and frequency resolutions. It is well-known that the most commonly used time-windowed Fourier transform, which provides a time-frequency representation, is limited by the intrinsic trade-off between time and frequency resolutions. Parametric methods have then been introduced as an alternative to overcome this resolution problem. However, the performance of those methods deteriorates when high non-stationarities are present in the Doppler signal. For the purpose of accurately estimating the Doppler frequency shift, even when the temporal flow velocity is rapid (high non-stationarity), we propose to combine the use of the time-varying autoregressive (AR) method and the (dominant) pole frequency. This proposed method performs well in the context where non-stationarities are very high. A comparative evaluation has been made between classical (FFT based) and AR (both block and recursive) algorithms. Among recursive algorithms we test an adaptive recursive method as well as a time-varying recursive method. Finally, the superiority of the time-varying parametric approach in terms of frequency tracking and delay in the frequency estimate is illustrated for both simulated and in vivo Doppler signals.

  3. The use of spectral skin reflectivity and laser doppler vibrometry data to determine the optimal site and wavelength to collect human vital sign signatures

    NASA Astrophysics Data System (ADS)

    Byrd, Kenneth A.; Kaur, Balvinder; Hodgkin, Van A.

    2012-06-01

    The carotid artery has been used extensively by researchers to demonstrate that Laser Doppler Vibrometry (LDV) is capable of exploiting vital sign signatures from cooperative human subjects at stando. Research indicates that, the carotid, although good for cooperative and non-traumatic scenarios, is one of the first vital signs to become absent or irregular when a casualty is hemorrhaging and in progress to circulatory (hypovolemic) shock. In an effort to determine the optimal site and wavelength to measure vital signs off human skin, a human subject data collection was executed whereby 14 subjects had their spectral skin reflectivity and vital signs measured at five collection sites (carotid artery, chest, back, right wrist and left wrist). In this paper, we present our findings on using LDV and re ectivity data to determine the optimal collection site and wavelength that should be used to sense pulse signals from quiet and relatively motionless human subjects at stando. In particular, we correlate maximum levels of re ectivity across the ensemble of 14 subjects with vital sign measurements made with an LDV at two ranges, for two scenarios.

  4. Imaging-based assessment of the mineral composition of urinary stones: an in vitro study of the combination of hounsfield unit measurement in noncontrast helical computerized tomography and the twinkling artifact in color Doppler ultrasound.

    PubMed

    Hassani, Hakim; Raynal, Gauthier; Spie, Romain; Daudon, Michel; Vallée, Jean-Noël

    2012-05-01

    We evaluated the value of combining noncontrast helical computerized tomography (NCHCT) and color Doppler ultrasound in the assessment of the composition of urinary stones. In vitro, we studied 120 stones of known composition, that separate into the five main types: 18 calcium oxalate monohydrate (COM) stones, 41 calcium oxalate dihydrate (COD) stones, 24 uric acid stones, 25 calcium phosphate stones and 12 cystine calculi. Stones were characterized in terms of their Hounsfield density (HU) in NCHCT and the presence of a twinkling artifact (TA) in color Doppler ultrasound. There were statistically significant HU differences between calcium and non-calcium stones (p < 0.001), calcium oxalate stones and calcium phosphate stones (p < 0.001) and uric acid stones and cystine calculi (p < 0.001) but not between COM and COD stones (p = 0.786). Hence, the HU was a predictive factor of the composition of all types of stones, other than for COM and COD stones within the calcium oxalate class (p > 0.05). We found that the TA does not enable differentiation between calcium and non-calcium stones (p > 0.999), calcium oxalate stones and calcium phosphate stones (p = 0.15), or uric acid stones and cystine calculi (p = 0.079). However, it did reveal a significant difference between COM and COD stones (p = 0.002). The absence of a TA is a predictive factor for the presence of COM stones (p = 0.008). Hence, the association of NCHCT and Doppler enables the accurate classification of the five types of stones in vitro.

  5. Standardized ultrasound evaluation of carotid stenosis for clinical trials: University of Washington Ultrasound Reading Center

    PubMed Central

    2010-01-01

    Introduction Serial monitoring of patients participating in clinical trials of carotid artery therapy requires noninvasive precision methods that are inexpensive, safe and widely available. Noninvasive ultrasonic duplex Doppler velocimetry provides a precision method that can be used for recruitment qualification, pre-treatment classification and post treatment surveillance for remodeling and restenosis. The University of Washington Ultrasound Reading Center (UWURC) provides a uniform examination protocol and interpretation of duplex Doppler velocity measurements. Methods Doppler waveforms from 6 locations along the common carotid and internal carotid artery path to the brain plus the external carotid and vertebral arteries on each side using a Doppler examination angle of 60 degrees are evaluated. The UWURC verifies all measurements against the images and waveforms for the database, which includes pre-procedure, post-procedure and annual follow-up examinations. Doppler angle alignment errors greater than 3 degrees and Doppler velocity measurement errors greater than 0.05 m/s are corrected. Results Angle adjusted Doppler velocity measurements produce higher values when higher Doppler examination angles are used. The definition of peak systolic velocity varies between examiners when spectral broadening due to turbulence is present. Examples of measurements are shown. Discussion Although ultrasonic duplex Doppler methods are widely used in carotid artery diagnosis, there is disagreement about how the examinations should be performed and how the results should be validated. In clinical trails, a centralized reading center can unify the methods. Because the goals of research examinations are different from those of clinical examinations, screening and diagnostic clinical examinations may require fewer velocity measurements. PMID:20822530

  6. Effects of prolonged surface pressure on the skin blood flowmotions in anaesthetized rats—an assessment by spectral analysis of laser Doppler flowmetry signals

    NASA Astrophysics Data System (ADS)

    Li, Zengyong; Tam, Eric W. C.; Kwan, Maggie P. C.; Mak, Arthur F. T.; Lo, Samuel C. L.; Leung, Mason C. P.

    2006-05-01

    The objective of this study is to assess the effect of prolonged surface compression on the skin blood flowmotion in rats using spectral analysis based on wavelets transform of the periodic oscillations of the cutaneous laser Doppler flowmetry (LDF) signal. An external pressure of 13.3 kPa (100 mmHg) was applied to the trochanter area and the distal lateral tibia of Sprague-Dawley rats via two specifically designed pneumatic indentors. The loading duration was 6 hours/day for 4 consecutive days. Five frequency intervals were identified (0.01-0.04 Hz, 0.04-0.15 Hz, 0.15-0.4 Hz, 0.4-2 Hz and 2-5 Hz) corresponding to endothelial related metabolic, neurogenic, myogenic, respiratory and cardiac origins. The absolute amplitude of oscillations of each particular frequency interval and the normalized amplitude were calculated for quantitative assessments. The results showed that (1) tissue compression following the above schedule induced significant decrease in the normalized amplitude in the frequency interval of 0.01-0.04 Hz both in the trochanter area (p < 0.001) and tibialis area (p = 0.023), (2) prolonged compression induced significant increase in the absolute amplitude (p = 0.004 for the trochanter area and p = 0.017 for the tibialis area) but significant decrease in the normalized amplitude (p = 0.023 for the trochanter area and p = 0.026 for the tibialis area) in the frequency interval of 0.15-0.4 Hz, and (3) at the tibialis area, the flowmotion amplitude (frequency interval 0.15-0.4 Hz) measured prior to the daily tissue compression schedule was found to be significantly higher on day 4 than the measurements obtained on day 1. However, this finding was not observed at the trochanter area. Our results suggested that prolonged compression might induce endothelial damage and affect the endothelial related metabolic activities.

  7. Doppler ion program description

    SciTech Connect

    Henline, P.

    1980-12-01

    The Doppler spectrometer is a conventional Czerny-Turner grating spectrometer with a 1024 channel multiple detector. Light is dispersed across the detector, and its output yields a spectrum covering approximately 200 A. The width of the spectral peak is directly proportional to the temperature of the emitting ions, and determination of the impurity ion temperature allows one to infer the plasma ion temperature. The Doppler ion software system developed at General Atomic uses a TRACOR Northern 1710-31 and an LSI-11/2. The exact configuration of Doublet III is different from TRACOR Northern systems at other facilities.

  8. The Detection and Exclusion of the Prostate Neuro-Vascular Bundle (NVB) in Automated HIFU Treatment Planning Using a Pulsed-Wave Doppler Ultrasound System

    NASA Astrophysics Data System (ADS)

    Chen, Wohsing; Carlson, Roy F.; Fedewa, Russell; Seip, Ralf; Sanghvi, Narendra T.; Dines, Kris A.; Pfile, Richard; Penna, Michael A.; Gardner, Thomas A.

    2005-03-01

    Men with prostate cancer are likely to develop impotence after prostate cancer therapy if the treatment damages the neuro-vascular bundles (NVB). The NVB are generally located at the periphery of the prostate gland. To preserve the NVB, a Doppler system is used to detect and localize the associated blood vessels. This information is used during the therapy planning procedure to avoid treatment surrounding the blood vessel areas. The Sonablate®500 (Focus Surgery, Inc.) image-guided HIFU device is enhanced with a pulse-wave multi-gate Doppler system that uses the current imaging transducer and mechanical scanner to acquire Doppler data. Doppler detection is executed after the regular B-mode images are acquired from the base to the apex of the prostate using parallel sector scans. The results are stored and rendered in 3-D display, registered with additional models generated for the capsule, urethra, and rectal wall, and the B-mode data and treatment plan itself. The display of the blood flow can be in 2-D color overlaid on the B-mode image or in 3-D color structure. Based on this 3-D model, the HIFU treatment planning can be executed in automated or manual mode by the physician to remove originally defined treatment zones that overlap with the NVB (for preservation of NVB). The results of the NVB detection in animal experiments, and the 3-D modeling and data registration of the prostate will be presented.

  9. Effectiveness of evaluating tumor vascularization using 3D power Doppler ultrasound with high-definition flow technology in the prediction of the response to neoadjuvant chemotherapy for T2 breast cancer: a preliminary report

    NASA Astrophysics Data System (ADS)

    Shia, Wei-Chung; Chen, Dar-Ren; Huang, Yu-Len; Wu, Hwa-Koon; Kuo, Shou-Jen

    2015-10-01

    The aim of this study was to evaluate the effectiveness of advanced ultrasound (US) imaging of vascular flow and morphological features in the prediction of a pathologic complete response (pCR) and a partial response (PR) to neoadjuvant chemotherapy for T2 breast cancer. Twenty-nine consecutive patients with T2 breast cancer treated with six courses of anthracycline-based neoadjuvant chemotherapy were enrolled. Three-dimensional (3D) power Doppler US with high-definition flow (HDF) technology was used to investigate the blood flow in and morphological features of the tumors. Six vascularity quantization features, three morphological features, and two vascular direction features were selected and extracted from the US images. A support vector machine was used to evaluate the changes in vascularity after neoadjuvant chemotherapy, and pCR and PR were predicted on the basis of these changes. The most accurate prediction of pCR was achieved after the first chemotherapy cycle, with an accuracy of 93.1% and a specificity of 85.5%, while that of a PR was achieved after the second cycle, with an accuracy of 79.31% and a specificity of 72.22%. Vascularity data can be useful to predict the effects of neoadjuvant chemotherapy. Determination of changes in vascularity after neoadjuvant chemotherapy using 3D power Doppler US with HDF can generate accurate predictions of the patient response, facilitating early decision-making.

  10. Quantitative Ultrasound in Cancer Imaging

    PubMed Central

    Feleppa, Ernest J.; Mamou, Jonathan; Porter, Christopher R.; Machi, Junji

    2010-01-01

    Ultrasound is a relatively inexpensive, portable, and versatile imaging modality that has a broad range of clinical uses. It incorporates many imaging modes, such as conventional gray-scale “B-mode” imaging to display echo amplitude in a scanned plane; M-mode imaging to track motion at a given fixed location over time; duplex, color, and power Doppler imaging to display motion in a scanned plane; harmonic imaging to display non-linear responses to incident ultrasound; elastographic imaging to display relative tissue stiffness; and contrast-agent imaging with simple contrast agents to display blood-filled spaces or with targeted agents to display specific agent-binding tissue types. These imaging modes have been well described in the scientific, engineering, and clinical literature. A less well-known ultrasonic imaging technology is based on quantitative ultrasound or (QUS), which analyzes the distribution of power as a function of frequency in the original received echo signals from tissue and exploits the resulting spectral parameters to characterize and distinguish among tissues. This article discusses the attributes of QUS-based methods for imaging cancers and providing improved means of detecting and assessing tumors. The discussion will include applications to imaging primary prostate cancer and metastatic cancer in lymph nodes to illustrate the methods. PMID:21362522

  11. Doppler echocardiography

    SciTech Connect

    Labovitz, A.J.; Williams, G.A.

    1988-01-01

    The authors are successful in presenting a basic book on clinical quantitative Doppler echocardiography. It is not intended to be a comprehensive text, but it does cover clinical applications in a succinct fashion. Only the more common diseases in the adult are considered. The subjects are presented logically and are easy to comprehend. The illustrations are good, and the book is paperbound. The basic principles of Doppler echocardiography are presented briefly. The book ends with chapters on left ventricular function (stroke volume and cardiac output), congenital heart disease, and color Doppler echo-cardiography. There are numerous references and a good glossary and index.

  12. Hyperhomocysteinemia as an Early Predictor of Erectile Dysfunction: International Index of Erectile Function (IIEF) and Penile Doppler Ultrasound Correlation With Plasma Levels of Homocysteine.

    PubMed

    Giovannone, Riccardo; Busetto, Gian Maria; Antonini, Gabriele; De Cobelli, Ottavio; Ferro, Matteo; Tricarico, Stefano; Del Giudice, Francesco; Ragonesi, Giulia; Conti, Simon L; Lucarelli, Giuseppe; Gentile, Vincenzo; De Berardinis, Ettore

    2015-09-01

    Erectile dysfunction (ED) is inability to achieve and maintain an erection to permit satisfactory sexual activity. Homocysteine (Hcys) is a sulfur-containing amino acid synthesized from the essential amino acid methionine. Experimental models have elucidated the role of hyperhomocysteinemia (HHcys) as a strong and independent predictor for atherosclerosis progression and impaired cavernosal perfusion. The aim of this study is to investigate the serum levels of Hcys in our cohort of patients with ED, to compare these values with these of control population and to examine Hcys as a predictive marker for those patients who are beginning to complain mild-moderate ED. A total of 431 patients were enrolled in the study. The whole cohort was asked to complete the International Index of Erectile Function (IIEF) questionnaire. The study population was divided in 3 main groups: Group A: 145 patients with no ED serving as a control group; Group B: 145 patients with mild or mild-moderate ED; Group C: 141 patients with moderate or severe ED. Each participant underwent blood analysis. All patients underwent baseline and dynamic penile Doppler ultrasonography. We found in our cohort mean Hcys plasma concentrations significantly higher than the cut-off point in both groups B and C (18.6 ± 4.7 and 28.38 ± 7.8, respectively). Mean IIEF score was 27.9 ± 1.39, 19.5 ± 2.6, and 11.1 ± 2.5 for groups A, B, and C, respectively (P < 0.0001). In the penile Doppler ultrasonography studies, a high significant inverse correlation was detected between the mean values of the 10th minute's peak-systolic velocity (PSV) and Hcys levels for the groups B and C. This establishes a dose-dependent association between Hcys and ED. Furthermore, we showed that Hcys was an earlier predictor of ED than Doppler studies, as the Hcys increase was present in patients with mild ED even before abnormal Doppler values.

  13. Denoising of arterial and venous Doppler signals using discrete wavelet transform: effect on clinical parameters.

    PubMed

    Tokmakçi, Mahmut; Erdoğan, Nuri

    2009-05-01

    In this paper, the effects of a wavelet transform based denoising strategy on clinical Doppler parameters are analyzed. The study scheme included: (a) Acquisition of arterial and venous Doppler signals by sampling the audio output of an ultrasound scanner from 20 healthy volunteers, (b) Noise reduction via decomposition of the signals through discrete wavelet transform, (c) Spectral analysis of noisy and noise-free signals with short time Fourier transform, (d) Curve fitting to spectrograms, (e) Calculation of clinical Doppler parameters, (f) Statistical comparison of parameters obtained from noisy and noise-free signals. The decomposition level was selected as the highest level at which the maximum power spectral density and its corresponding frequency were preserved. In all subjects, noise-free spectrograms had smoother trace with less ripples. In both arterial and venous spectrograms, denoising resulted in a significant decrease in the maximum (systolic) and mean frequency, with no statistical difference in the minimum (diastolic) frequency. In arterial signals, this leads to a significant decrease in the calculated parameters such as Systolic/Diastolic Velocity Ratio, Resistivity Index, Pulsatility Index and Acceleration Time. Acceleration Index did not change significantly. Despite a successful denoising, the effects of wavelet decomposition on high frequency components in the Doppler signal should be challenged by comparison with reference data, or, through clinical investigations.

  14. Standards of the Polish Ultrasound Society - Update. Ultrasound examination of renal arteries.

    PubMed

    Drelich-Zbroja, Anna

    2014-09-01

    This paper has been prepared on the basis of the Standards of the Polish Ultrasound Society and updated based on the latest reports from the relevant literature. The author presents a renal artery examination technique, patient preparation for the testing, limitations of the method, currently recommended proper blood flow standards and criteria for the diagnosis of significant stenoses. Renal artery ultrasound is performed using a 2-5 MHz probe, usually a convex 3.5 MHz one. The ultrasound machine must be equipped with the Doppler options for the evaluation of color coded blood flow and recording of the blood flow spectrum, including the triplex Doppler mode. Patients have to fast for at least eight hours before testing. Ultrasound always begins with the assessment of renal structure using the grayscale. Next, color coded blood flow imaging is used, followed by placing a sampling gate in the lumen of the target vessel to record the spectral image. The aim of renal artery ultrasound is to assess the course and position of arteries, evaluate blood flow parameters, as well as visualize possible changes: stenoses, occlusions, aneurysms, or arteriovenous fistulas. Blood flow velocity is always measured in a longitudinal projection/ longitudinal section of the vessel, after placing the sampling gate in the central part of the flowing bloodstream, which normally corresponds to the central part of the vascular cross-section. When diagnosing renal artery stenosis, it is necessary to know the nature of the blood flow and norms for flow parameters in healthy vessels. The spectrum of the blood flow velocity in renal arteries and their branches is a low resistance one. The following parameters are used to evaluate normal renal arteries and to identify the narrowed ones: Vmax, Vmin, RAR, AT, AI, RI and PI.

  15. Physics and instrumentation of ultrasound.

    PubMed

    Lawrence, John P

    2007-08-01

    A thorough understanding of the physics of ultrasound waves and the instrumentation will provide the user with a better understanding of the capabilities and limitations of ultrasound equipment. The ultrasound machine combines two technologies: image production (M-mode and 2-dimensional imaging) with Doppler assessment (continuous and pulse wave as well as color-flow mapping). These distinct technologies have been combined to provide the examiner with the ability to make accurate and comprehensive diagnoses and guide therapeutic intervention.

  16. Evaluation of Cloud Microphysics Simulated using a Meso-Scale Model Coupled with a Spectral Bin Microphysical Scheme through Comparison with Observation Data by Ship-Borne Doppler and Space-Borne W-Band Radars

    NASA Technical Reports Server (NTRS)

    Iguchi, T.; Nakajima, T.; Khain, A. P.; Saito, K.; Takemura, T.; Okamoto, H.; Nishizawa, T.; Tao, W.-K.

    2012-01-01

    Equivalent radar reflectivity factors (Ze) measured by W-band radars are directly compared with the corresponding values calculated from a three-dimensional non-hydrostatic meso-scale model coupled with a spectral-bin-microphysical (SBM) scheme for cloud. Three case studies are the objects of this research: one targets a part of ship-borne observation using 95 GHz Doppler radar over the Pacific Ocean near Japan in May 2001; other two are aimed at two short segments of space-borne observation by the cloud profiling radar on CloudSat in November 2006. The numerical weather prediction (NWP) simulations reproduce general features of vertical structures of Ze and Doppler velocity. A main problem in the reproducibility is an overestimation of Ze in ice cloud layers. A frequency analysis shows a strong correlation between ice water contents (IWC) and Ze in the simulation; this characteristic is similar to those shown in prior on-site studies. From comparing with the empirical correlations by the prior studies, the simulated Ze is overestimated than the corresponding values in the studies at the same IWC. Whereas the comparison of Doppler velocities suggests that large-size snowflakes are necessary for producing large velocities under the freezing level and hence rules out the possibility that an overestimation of snow size causes the overestimation of Ze. Based on the results of several sensitivity tests, we conclude that the source of the overestimation is a bias in the microphysical calculation of Ze or an overestimation of IWC. To identify the source of the problems needs further validation research with other follow-up observations.

  17. Cerebral laterality for language is related to adult salivary testosterone levels but not digit ratio (2D:4D) in men: A functional transcranial Doppler ultrasound study.

    PubMed

    Papadatou-Pastou, Marietta; Martin, Maryanne

    2017-03-01

    The adequacy of three competing theories of hormonal effects on cerebral laterality are compared using functional transcranial Doppler sonography (fTCD). Thirty-three adult males participated in the study (21 left-handers). Cerebral lateralization was measured by fTCD using an extensively validated word generation task. Adult salivary testosterone (T) and cortisol (C) concentrations were measured by luminescence immunoassay and prenatal T exposure was indirectly estimated by the somatic marker of 2nd to 4th digit length ratio (2D:4D). A significant quadratic relationship between degree of cerebral laterality for language and adult T concentrations was observed, with enhanced T levels for strong left hemisphere dominance and strong right hemisphere dominance. No systematic effects on laterality were found for cortisol or 2D:4D. Findings suggest that higher levels of T are associated with a relatively attenuated degree of interhemispheric sharing of linguistic information, providing support for the callosal and the sexual differentiation hypotheses rather than the Geschwind, Behan and Galaburda (GBG) hypothesis.

  18. Current clinical applications of spectral tissue Doppler echocardiography (E/E' ratio) as a noninvasive surrogate for left ventricular diastolic pressures in the diagnosis of heart failure with preserved left ventricular systolic function

    PubMed Central

    Arques, Stephane; Roux, Emmanuel; Luccioni, Roger

    2007-01-01

    Congestive heart failure with preserved left ventricular systolic function has emerged as a growing epidemic medical syndrome in developed countries, which is characterized by high morbidity and mortality rates. Rapid and accurate diagnosis of this condition is essential for optimizing the therapeutic management. The diagnosis of congestive heart failure is challenging in patients presenting without obvious left ventricular systolic dysfunction and additional diagnostic information is most commonly required in this setting. Comprehensive Doppler echocardiography is the single most useful diagnostic test recommended by the ESC and ACC/AHA guidelines for assessing left ventricular ejection fraction and cardiac abnormalities in patients with suspected congestive heart failure, and non-invasively determined basal or exercise-induced pulmonary capillary hypertension is likely to become a hallmark of congestive heart failure in symptomatic patients with preserved left ventricular systolic function. The present review will focus on the current clinical applications of spectral tissue Doppler echocardiography used as a reliable noninvasive surrogate for left ventricular diastolic pressures at rest as well as during exercise in the diagnosis of heart failure with preserved left ventricular systolic function. Chronic congestive heart failure, a disease of exercise, and acute heart failure syndromes are characterized by specific pathophysiologic and diagnostic issues, and these two clinical presentations will be discussed separately. PMID:17386087

  19. [Quantification and monitoring of vascular resistance in the lower limbs by the Doppler method (animal model)

    NASA Technical Reports Server (NTRS)

    Arbeille, P.; Berson, M.; Blondeau, B.; Durand, A.; Bodard, S.; Locatelli, A.; Fox, G. E. (Principal Investigator)

    1995-01-01

    The object of this study was to define and validate a non-invasive method of evaluation and monitoring of vascular resistances in the leg. Blood flow velocity was measured by Doppler ultrasound in an animal model (ewe) with similar blood flow characteristics in the lower limb as man and allowing access to the required invasive measurements for validation of the method (pressure and flow). Vascular resistances distal to the measuring point (femoral, for example) were assessed using the resistance index R = D/S, S being the peak systolic deflection and D that of diastolic reflux of the Doppler spectral analysis of flow in the femoral artery. The values and variations of this resistance index were compared with the vascular resistances calculated from measurements of pressure and flow at the point of Doppler sampling and expressed in mmHg/ml/min. Femoral flow was measured by Doppler ultrasound (Doppler-echo), and mean pressure by an arterial catheter introduced into the abdominal aorta. Compression of the lower limb veins induced a venous return resulting in a reduction of cardiac output and femoral flow. During compression, femoral flow decreased by an average of 29% (p < 0.001) although mean pressure and heart rate did not change significantly. The femoral resistance index (Rf) increased by an average of 37.5% (p < 0.01) and vascular resistances increased by 45.9% (p < 0.01). Injection of 1 mg adrenaline induced peripheral vasoconstriction with an increase in blood pressure and a decrease in heart rate and femoral flow.(ABSTRACT TRUNCATED AT 250 WORDS).

  20. In vitro evaluation of volumetric flow from Doppler power-weighted and amplitude-weighted mean velocities.

    PubMed

    Minich, L L; Snider, A R; Meliones, J N; Yanock, C

    1993-01-01

    Ultrasound theory suggests that the volume of flow is directly related to the power and amplitude of the backscattered Doppler signals. To evaluate the accuracy of volume flow calculated with power-weighted and amplitude-weighted mean velocities (PWMV and AWMV), volume flows were measured in a pulsatile flow-tank system equipped with a 1.25 cm diameter simulated femoral artery. Analyses were performed throughout a range of physiologic flows, mean driving pressures, and pulse rates. At each hemodynamic setting, volume flow in the simulated artery was measured with an electromagnetic flow probe and with pulsed Doppler echocardiography by use of 7.0 and 3.5 MHz transducers. In addition, to determine the effects of vessel size and parabolic flow on the accuracy of the Doppler volumes, volume flow was evaluated in several differently sized vessels at sampling distances of 20 times the vessel diameter downstream from the orifice. On the ultrasound system, PWMV was calculated as the sum of the individual velocities multiplied by their respective power fractions (the fraction of the total instantaneous power represented by the individual signal power). The instantaneous PWMV was plotted continuously in time and superimposed on the spectral recording. Similarly, AWMV was calculated with amplitudes measured as the square root of the signal power. The PWMV and AWMV were integrated over the flow period and multiplied by the known cross-sectional area of flow to obtain the Doppler volume. In all analyses performed, volumetric flows calculated with Doppler echocardiography with PWMV and AWMV correlated extremely well with those measured with the electromagnetic flow probe. Thus, over a wide range of physiologic conditions, transducers frequencies, and vessel sizes, volume flow can be accurately calculated from PWMV and AWMV Doppler data. This technique provides an accurate, automatic method for on-line determination of volumetric flow.

  1. ANL Doppler flowmeter

    NASA Astrophysics Data System (ADS)

    Karplus, H. B.; Raptis, A. C.; Lee, S.; Simpson, T.

    1985-10-01

    A flowmeter has been developed for measuring flow velocity in hot slurries. The flowmeter works on an ultrasonic Doppler principle in which ultrasound is injected into the flowing fluid through the solid pipe wall. Isolating waveguides separate the hot pipe from conventional ultrasonic transducers. Special clamp-on high-temperature transducers also can be adapted to work well in this application. Typical flows in pilot plants were found to be laminar, giving rise to broad-band Doppler spectra. A special circuit based on a servomechanism sensor was devised to determine the frequency average of such a broad spectrum. The device was tested at different pilot plants. Slurries with particulates greater than 70 microns (0.003 in.) yielded good signals, but slurries with extremely fine particulates were unpredictable. Small bubbles can replace the coarse particles to provide a good signal if there are not too many. Successful operation with very fine particulate slurries may have been enhanced by the presence of microbubbles.

  2. Skin Ultrasound in Kaposi Sarcoma.

    PubMed

    Carrascosa, R; Alfageme, F; Roustán, G; Suarez, M D

    2016-05-01

    The use of ultrasound imaging has recently been increasing in numerous dermatologic diseases. This noninvasive technique provides additional details on the structure and vascularization of skin lesions. Kaposi sarcoma is a vascular tumor that typically arises in the skin and mucosas. It can spread to lymph nodes and internal organs. We performed B-mode and color Doppler ultrasound studies in 3 patients with a clinical diagnosis of Kaposi sarcoma confirmed by histological examination. We found differences in the ultrasound pattern between nodular and plaque lesions, in both B-mode and color Doppler. We believe that skin ultrasound imaging could be a useful technique for studying cutaneous Kaposi sarcoma, providing additional information on the structural and vascular characteristics of the lesion.

  3. Doppler effect's contribution to ultrasonic modulation of multiply scattered coherent light: Monte Carlo modeling.

    PubMed

    Elazar, Jovan M; Steshenko, Oleg

    2008-01-15

    Modulation of light by ultrasound in turbid media is investigated by modified public domain software based on the Monte Carlo algorithm. Apart from the recognized modulation mechanisms, originating in scatterers' displacements and refractive index modulation, an additional mechanism, evolving from Doppler shift during photon scattering, is considered. Comparison of the relative contributions from all three mechanisms to light modulation by ultrasound is performed for different medium scattering properties and ultrasound frequencies. Refractive index modulation remains the strongest mechanism for light modulation by ultrasound, but for high ultrasound frequencies and for large scattering coefficients the Doppler effect can become dominant.

  4. Doppler flowmeter

    DOEpatents

    Karplus, Henry H. B.; Raptis, Apostolos C.

    1983-01-01

    A Doppler flowmeter impulses an ultrasonic fixed-frequency signal obliquely into a slurry flowing in a pipe and a reflected signal is detected after having been scattered off of the slurry particles, whereby the shift in frequencies between the signals is proportional to the slurry velocity and hence slurry flow rate. This flowmeter filters the Doppler frequency-shift signal, compares the filtered and unfiltered shift signals in a divider to obtain a ratio, and then further compares this ratio against a preset fractional ratio. The flowmeter utilizes a voltage-to-frequency convertor to generate a pulsed signal having a determinable rate of repetition precisely proportional to the divergence of the ratios. The pulsed signal serves as the input control for a frequency-controlled low-pass filter, which provides thereby that the cutoff frequency of the filtered signal is known. The flowmeter provides a feedback control by minimizing the divergence. With the cutoff frequency and preset fractional ratio known, the slurry velocity and hence flow will also be determinable.

  5. Doppler flowmeter

    DOEpatents

    Karplus, H.H.B.; Raptis, A.C.

    1981-11-13

    A Doppler flowmeter impulses an ultrasonic fixed-frequency signal obliquely into a slurry flowing in a pipe and a reflected signal is detected after having been scattered off of the slurry particles, whereby the shift in frequencies between the signals is proportional to the slurry velocity and hence slurry flow rate. This flowmeter filters the Doppler frequency-shift signal, compares the filtered and unfiltered shift signals in a divider to obtain a ratio, and then further compares this ratio against a preset fractional ratio. The flowmeter utilizes a voltage-to-frequency convertor to generate a pulsed signal having a determinable rate of repetition precisely proportional to the divergence of the ratios. The pulsed signal serves as the input control for a frequency-controlled low-pass filter, which provides thereby that the cutoff frequency of the filtered signal is known. The flowmeter provides a feedback control by minimizing the divergence. With the cutoff frequency and preset fractional ratio known, the slurry velocity and hence flow will also be determinable.

  6. Abdominal Ultrasound

    MedlinePlus

    ... Ultrasound - Abdomen Ultrasound imaging of the abdomen uses sound waves to produce pictures of the structures within ... pictures of the inside of the body using sound waves. Ultrasound imaging, also called ultrasound scanning or ...

  7. Hip Ultrasound

    MedlinePlus

    ... Index A-Z Hip Ultrasound Hip ultrasound uses sound waves to produce pictures of muscles, tendons, ligaments, ... pictures of the inside of the body using sound waves. Ultrasound imaging, also called ultrasound scanning or ...

  8. Obstetrical Ultrasound

    MedlinePlus

    ... Index A-Z Obstetric Ultrasound Obstetric ultrasound uses sound waves to produce pictures of a baby (embryo ... pictures of the inside of the body using sound waves. Ultrasound imaging, also called ultrasound scanning or ...

  9. Comparison of ultrasound biomicroscopy and spectral-domain anterior segment optical coherence tomography in evaluation of anterior segment after laser peripheral iridotomy

    PubMed Central

    Ma, Xiao-Yun; Zhu, Dan; Zou, Jun; Zhang, Wen-Jie; Cao, Yi-Lin

    2016-01-01

    AIM To quantitatively assess narrow anterior chamber angle using spectral-domain anterior segment optical coherence tomography (SD-AS-OCT) and ultrasound biomicroscopy (UBM), and to evaluate the correlations and consistency between SD-AS-OCT and UBM. METHODS Fifty-five eyes from 40 patients were examined. Patients were diagnosed with primary angle-closure glaucoma (PACG) remission (11 eyes from 8 patients), primary angle closure (PAC, 20 eyes from 20 patients) and PAC suspect (24 eyes from 12 patients). Each eye was examined by SD-AS-OCT and UBM after laser peripheral iridotomy (LPI). The measurements of SD-AS-OCT were angle open distance (AOD), anterior chamber angle (ACA), trabecular iris angle (TIA), and trabecular iris space area (TISA). UBM measurements were AOD and TIA. Correlations of AOD500 and TIA500 between UBM and AS-OCT were assessed. All parameters were analysed by SPSS 16.0 and MedCalc. RESULTS ACA, TIA and AOD measured by SD-AS-OCT reached a maximum at the temporal quadrant and minimum at the nasal quadrant. TISA reached the maximum at the inferior and minimum at the superior quadrant. Group parameters of AOD500 and AOD750 showed a linear positive correlation, and AOD750 had less variability. UBM outcomes of AOD500 and TIA500 were significantly smaller than those of SD-AS-OCT. The results of the two techniques were correlated at the superior, nasal and inferior quadrants. CONCLUSION Both UBM and SD-AS-OCT are efficient tools for follow-up during the course of PACG. We recommended using parameters at 750 µm anterior to the sclera spur for the screening and follow-up of PACG and PAC. The two methods might be alternatives to each other. PMID:27158613

  10. Normal Doppler velocimetry of renal vasculature in Persian cats.

    PubMed

    Carvalho, Cibele F; Chammas, Maria C

    2011-06-01

    Renal diseases are common in older cats. Decreased renal blood flow may be the first sign of dysfunction and can be evaluated by Doppler ultrasound. But previous studies suggest that the resistive index (RI) has a low sensitivity for detecting renal disease. Doppler waveforms of renal and intrarenal arteries demonstrate decreased blood flow before there are any changes in the RI. The purpose of this study was to evaluate the normal Doppler flowmetrics parameters of renal arteries (RAs), interlobar arteries (IAs) and abdominal aorta (AO) in adult healthy, Persian cats. Twenty-five Persian cats (13 females and 12 males with mean age of 30 months and an age range 12-60 months) with normal clinical examinations and biochemical tests and normal systemic blood pressure were given B-mode ultrasonographies in order to exclude all nephropathies, including polycystic kidney disease. All measurements were performed on both kidneys. Both kidneys (n=50) were examined by color mapping of the renal vasculature. Pulsed Doppler was used to examine both RAs, the IAs at cranial, middle and caudal sites, and the AO. The RI was calculated for all of the vessels. Early systolic acceleration (ESA) of RA and IA was obtained with Doppler spectral analysis. Furthermore, the ratio indices between RA/AO, and IA/RA velocities were calculated. The mean values of peak systolic velocity (PSV) and the diameter for AO were 53.17±13.46 cm/s and 0.38±0.08 cm, respectively. The mean RA diameter for all 50 kidneys was 0.15±0.02 cm. Considering the velocimetric values in both RAs, the mean PSV and RI that were obtained were 41.17±9.40 cm/s and 0.54±0.07. The RA had a mean ESA of 1.12±1.14 m/s(2) and the calculated upper limit of the reference value was 3.40 m/s(2). The mean renal-aortic ratio was 0.828±0.296. The IA showed PSV and RI values of 32.16±9.33 cm/s and 0.52±0.06, respectively. The mean ESA of all IAs was 0.73±0.61 m/s(2). The calculated upper limit of the reference value was 2.0m

  11. Renal power Doppler ultrasonographic evaluation of children with acute pyelonephritis.

    PubMed

    Shajari, Ahmad; Nafisi-Moghadam, Reza; Malek, Mahrooz; Smaili, Agha; Fallah, Mahmud; Pahlusi, Ali

    2011-01-01

    Urinary tract infections are common in children. The available gold standard method for diagnosis, Tc-99m dimercaptosuccinic acid scan is expensive and exposes patients to considerable amount of radiation. This study was performed to compare and assess the efficacy of Power Doppler Ultrasound versus Tc-99m DMSA scan for diagnosis of acute pyelonephritis. A quasi experimental study was conducted on 34 children with mean age of 2.8 ± 2.7 years who were hospitalized with their first episode of febrile urinary tract infection. All children were evaluated in the first 3 days of admission by Doppler Ultrasound and Tc-99m DMSA scan. Patients with congenital structural anomalies were excluded. Each kidney was divided into three zones. The comparison between efficacy of Doppler Ultrasound and DMSA scan was carried out based on number of patients and on classified renal units. Based on the number of patients enrolled; the sensitivity, specificity, positive and negative predictive values and accuracy of Doppler Ultrasound were 89%, 53%, 70%, 80% and 74%, respectively but based on the renal units, it was 66%, 81%, 46%, 91% and 79% , respectively. Although Doppler Ultrasound has the potential for identifying acute pyelonephritis in children, but it is still soon to replace DMSA scan.

  12. Breast ultrasound.

    PubMed

    Ueno, E

    1996-03-01

    In ultrasound, ultrasonic images are formed by means of echoes among tissues with different acoustic impedance. Acoustic impedance is the product of sound speed and bulk modulus. The bulk modulus expresses the elasticity of an object, and in the human body, the value is increased by conditions such as fibrosis and calcification. The sound speed is usually high in elastic tissues and low in water. In the body, it is lowest in the fatty tissue. Ultrasound echoes are strong on the surface of bones which are hard and have a high sound speed. In organs filled with air such as the lungs, the bulk modulus is low and the sound speed is extremely low at 340 m/s, which produce strong echoes (the sound speed in solid tissues is 1,530 m/s). Human tissue is constructed of units smaller than the ultrasonic beam, and it is necessary to understand back-scattering in order to understand the ultrasonic images of these tissues. When ultrasound passes through tissue, it is absorbed as thermal energy and attenuated. Fiber is a tissue with a high absorption and attenuation rate. When the rate increases, the posterior echoes are attenuated. However, in masses with a high water content such as cysts, the posterior echoes are accentuated. This phenomenon is an important, basic finding for determining the properties of tumors. Breast cancer can be classified into two types: stellate carcinoma and circumscribed carcinoma. Since stellate carcinoma is rich in fiber, the posterior echoes are attenuated or lacking. However, circumscribed carcinoma has a high cellularity and the posterior echoes are accentuated. The same tendency is also seen in benign tumors. In immature fibroadenomas, posterior echoes are accentuated, while in fibroadenomas with hyalinosis, the posterior echoes are attenuated. Therefore, if the fundamentals of this tissue characterization and the histological features are understood, reading of ultrasound becomes easy. Color Doppler has also been developed and has contributed

  13. In-suit Doppler technology assessment

    NASA Technical Reports Server (NTRS)

    Schulze, Arthur E.; Greene, Ernest R.; Nadeau, John J.

    1991-01-01

    The objective of this program was to perform a technology assessment survey of non-invasive air embolism detection utilizing Doppler ultrasound methodologies. The primary application of this technology will be a continuous monitor for astronauts while performing extravehicular activities (EVA's). The technology assessment was to include: (1) development of a full understanding of all relevant background research; and (2) a survey of the medical ultrasound marketplace for expertise, information, and technical capability relevant to this development. Upon completion of the assessment, LSR was to provide an overview of technological approaches and R&D/manufacturing organizations.

  14. Assessment of myofascial trigger points (MTrPs): a new application of ultrasound imaging and vibration sonoelastography.

    PubMed

    Sikdar, Siddhartha; Shah, Jay P; Gilliams, Elizabeth; Gebreab, Tadesse; Gerber, Lynn H

    2008-01-01

    Myofascial trigger points (MTrPs) are palpable hyperirritable nodules in skeletal muscle that are associated with chronic musculoskeletal pain. The goal of this study was to image MTrPs in the upper trapezius muscle using 2D gray scale ultrasound (US) and vibration sonoelastography (VSE) for differentiating the soft tissue characteristics of MTrPs compared to surrounding muscle. MTrPs appeared as hypoechoeic elliptically-shaped focal regions within the trapezius muscle on 2D US. Audio-frequency vibrations (100-250 Hz) were induced in the trapezius muscle of four volunteers with clinically identifiable MTrPs, and the induced vibration amplitudes were imaged using the color Doppler variance mode, and were further quantified using spectral Doppler analysis. Spectral Doppler analysis showed that vibration amplitudes were 27% lower on average within the MTrP compared to surrounding tissue (p0.05). Color variance imaging consistently detected a focal region of reduced vibration amplitude, which correlated with the hypoechoeic region identified as an MTrP (r =0.76 for area). Real-time 2D US identifies MTrPs, and VSE is feasible for differentiating MTrPs from surrounding tissue. Preliminary findings show that MTrPs are hypoechoeic on 2D US and the relative stiffness of MTrPs can be quantified using VSE. Ultrasound offers a convenient, accessible and low-risk approach for identifying MTrPs and for evaluating clinical observations of palpable, painful nodules.

  15. Doppler micro sense and avoid radar

    NASA Astrophysics Data System (ADS)

    Gorwara, Ashok; Molchanov, Pavlo; Asmolova, Olga

    2015-10-01

    There is a need for small Sense and Avoid (SAA) systems for small and micro Unmanned Aerial Systems (UAS) to avoid collisions with obstacles and other aircraft. The proposed SAA systems will give drones the ability to "see" close up and give them the agility to maneuver through tight areas. Doppler radar is proposed for use in this sense and avoid system because in contrast to optical or infrared (IR) systems Doppler can work in more harsh conditions such as at dusk, and in rain and snow. And in contrast to ultrasound based systems, Doppler can better sense small sized obstacles such as wires and it can provide a sensing range from a few inches to several miles. An SAA systems comprised of Doppler radar modules and an array of directional antennas that are distributed around the perimeter of the drone can cover the entire sky. These modules are designed so that they can provide the direction to the obstacle and simultaneously generate an alarm signal if the obstacle enters within the SAA system's adjustable "Protection Border". The alarm signal alerts the drone's autopilot to automatically initiate an avoidance maneuver. A series of Doppler radar modules with different ranges, angles of view and transmitting power have been designed for drones of different sizes and applications. The proposed Doppler radar micro SAA system has simple circuitry, works from a 5 volt source and has low power consumption. It is light weight, inexpensive and it can be used for a variety of small unmanned aircraft.

  16. Doppler and speckle methods for diagnostics in dentistry

    NASA Astrophysics Data System (ADS)

    Ulyanov, Sergey S.; Lepilin, Alexander V.; Lebedeva, Nina G.; Sedykh, Alexey V.; Kharish, Natalia A.; Osipova, Yulia; Karpovich, Alexander

    2002-02-01

    The results of statistical analysis of Doppler spectra of scattered intensity, obtained from tissues of oral cavity membrane of healthy volunteers, are presented. The dependence of the spectral moments of Doppler signal on cutoff frequency is investigated. Some results of statistical analysis of Doppler spectra, obtained from tooth pulp of patients, are presented. New approach for monitoring of blood microcirculation in orthodontics is suggested. Influence of own noise of measuring system on formation of speckle-interferometric signal is studied.

  17. Ultrasound -- Vascular

    MedlinePlus

    ... waves. Ultrasound imaging, also called ultrasound scanning or sonography , involves the use of a small transducer (probe) and ultrasound gel placed directly on the skin. High-frequency sound waves are transmitted from the ...

  18. Ultrasound - Breast

    MedlinePlus

    ... waves. Ultrasound imaging, also called ultrasound scanning or sonography , involves the use of a small transducer (probe) and ultrasound gel placed directly on the skin. High-frequency sound waves are transmitted from the ...

  19. Ultrasound -- Pelvis

    MedlinePlus

    ... waves. Ultrasound imaging, also called ultrasound scanning or sonography , involves the use of a small transducer (probe) and ultrasound gel placed directly on the skin. High-frequency sound waves are transmitted from the ...

  20. Prostate Ultrasound

    MedlinePlus

    ... waves. Ultrasound imaging, also called ultrasound scanning or sonography , involves the use of a small transducer (probe) and ultrasound gel placed directly on the skin. High-frequency sound waves are transmitted from the ...

  1. Abdominal Ultrasound

    MedlinePlus

    ... waves. Ultrasound imaging, also called ultrasound scanning or sonography , involves the use of a small transducer (probe) and ultrasound gel placed directly on the skin. High-frequency sound waves are transmitted from the ...

  2. Obstetrical Ultrasound

    MedlinePlus

    ... waves. Ultrasound imaging, also called ultrasound scanning or sonography , involves the use of a small transducer (probe) and ultrasound gel placed directly on the skin. High-frequency sound waves are transmitted from the ...

  3. Musculoskeletal Ultrasound

    MedlinePlus

    ... waves. Ultrasound imaging, also called ultrasound scanning or sonography , involves the use of a small transducer (probe) and ultrasound gel placed directly on the skin. High-frequency sound waves are transmitted from the ...

  4. Hip Ultrasound

    MedlinePlus

    ... waves. Ultrasound imaging, also called ultrasound scanning or sonography , involves the use of a small transducer (probe) and ultrasound gel placed directly on the skin. High-frequency sound waves are transmitted from the ...

  5. Ultrasound - Scrotum

    MedlinePlus

    ... waves. Ultrasound imaging, also called ultrasound scanning or sonography , involves the use of a small transducer (probe) and ultrasound gel placed directly on the skin. High-frequency sound waves are transmitted from the ...

  6. Ultrasound - Breast

    MedlinePlus

    ... the examination. top of page What does the equipment look like? Ultrasound scanners consist of a console ... ultrasound that require biopsy are not cancers. Many facilities do not offer ultrasound screening, and the procedure ...

  7. Color Doppler Imaging of Cardiac Catheters Using Vibrating Motors

    PubMed Central

    Reddy, Kalyan E.; Light, Edward D.; Rivera, Danny J.; Kisslo, Joseph A.; Smith, Stephen W.

    2010-01-01

    We attached a miniature motor rotating at 11,000 rpm onto the proximal end of cardiac electrophysiological (EP) catheters in order to produce vibrations at the tip which were then visualized by color Doppler on ultrasound scanners. We imaged the catheter tip within a vascular graft submerged in a water tank using the Volumetrics Medical Imaging 3D scanner, the Siemens Sonoline Antares 2D scanner, and the Philips ie33 3D ultrasound scanner with TEE probe. The vibrating catheter tip was visualized in each case though results varied with the color Doppler properties of the individual scanner. PMID:19514134

  8. Cranial Ultrasound/Head Ultrasound

    MedlinePlus

    ... waves. Ultrasound imaging, also called ultrasound scanning or sonography , involves the use of a small transducer (probe) and ultrasound gel placed directly on the skin. High-frequency sound waves are transmitted from the ...

  9. Quantitation of stress echocardiography by tissue Doppler and strain rate imaging: a dream come true?

    PubMed

    Galderisi, Maurizio; Mele, Donato; Marino, Paolo Nicola

    2005-01-01

    Tissue Doppler (TD) is an ultrasound tool providing a quantitative agreement of left ventricular regional myocardial function in different modalities. Spectral pulsed wave (PW) TD, performed online during the examination, measures instantaneous myocardial velocities. By means of color TD, velocity images are digitally stored for subsequent off-line analysis and mean myocardial velocities are measured. An implementation of color TD includes strain rate imaging (SRI), based on post-processing conversion of regional velocities in local myocardial deformation rate (strain rate) and percent deformation (strain). These three modalities have been applied to stress echocardiography for quantitative evaluation of regional left ventricular function and detection of ischemia and viability. They present advantages and limitations. PWTD does not permit the simultaneous assessment of multiple walls and therefore is not compatible with clinical stress echocardiography while it could be used in a laboratory setting. Color TD provides a spatial map of velocity throughout the myocardium but its results are strongly affected by the frame rate. Both color TD and PWTD are also influenced by overall cardiac motion and tethering from adjacent segments and require reference velocity values for interpretation of regional left ventricular function. High frame rate (i.e. > 150 ms) post-processing-derived SRI can potentially overcome these limitations, since measurements of myocardial deformation have not any significant apex-to-base gradient. Preliminary studies have shown encouraging results about the ability of SRI to detect ischemia and viability, in terms of both strain rate changes and/or evidence of post-systolic thickening. SRI is, however, Doppler-dependent and time-consuming. Further technical refinements are needed to improve its application and introduce new ultrasound modalities to overcome the limitations of the Doppler-derived deformation analysis.

  10. Medical ultrasound systems.

    PubMed

    Powers, Jeff; Kremkau, Frederick

    2011-08-06

    Medical ultrasound imaging has advanced dramatically since its introduction only a few decades ago. This paper provides a short historical background, and then briefly describes many of the system features and concepts required in a modern commercial ultrasound system. The topics addressed include array beam formation, steering and focusing; array and matrix transducers; echo image formation; tissue harmonic imaging; speckle reduction through frequency and spatial compounding, and image processing; tissue aberration; Doppler flow detection; and system architectures. It then describes some of the more practical aspects of ultrasound system design necessary to be taken into account for today's marketplace. It finally discusses the recent explosion of portable and handheld devices and their potential to expand the clinical footprint of ultrasound into regions of the world where medical care is practically non-existent. Throughout the article reference is made to ways in which ultrasound imaging has benefited from advances in the commercial electronics industry. It is meant to be an overview of the field as an introduction to other more detailed papers in this special issue.

  11. DOPPLER WEATHER SYSTEM

    SciTech Connect

    Berlin, Gary J.

    2002-08-05

    The SRS Doppler Weather System consists of a Doppler Server, A Master Server (also known as the Weather Server), several Doppler Slave Servers, and client-side software program called the Doppler Radar Client. This system is used to display near rel-time images taken from the SRS Weather Center's Doppler Radar computer. The Doppler Server is software that resides on the SRS Doppler Computer. It gathers raw data, 24-bit color weather images via screen scraping ever five minutes as requested by the Master Server. The Doppler Server then reduces the 24-bit color images to 8-bit color using a fixed color table for analysis and compression. This preserves the fidelity of the image color and arranges the colors in specific order for display. At the time of color reduction, the white color used for the city names on the background images are remapped to a different index (color) of white that the white on the weather scale. The Weather Server places a time stamp on the image, then compresses the image and passes it to all Doppler Slave servers. Each of the Doppler Slave servers mainitain a circular buffer of the eight most current images representing the last 40 minutes of weather data. As a new image is added, the oldest drops off. The Doppler Radar Client is an optional install program for any site-wide workstation. When a Client session is started, the Client requests Doppler Slave server assignment from the Master Server. Upon its initial request to the Slave Server, the Client obtains all eight current images and maintains its own circular buffer, updating its images every five minutes as the Doppler Slave is updated. Three background reference images are stored as part of the Client. The Client brings up the appropriate background image, decompresses the doppler data, and displays the doppler data on the background image.

  12. Visualizing ultrasound through computational modeling

    NASA Technical Reports Server (NTRS)

    Guo, Theresa W.

    2004-01-01

    The Doppler Ultrasound Hematocrit Project (DHP) hopes to find non-invasive methods of determining a person s blood characteristics. Because of the limits of microgravity and the space travel environment, it is important to find non-invasive methods of evaluating the health of persons in space. Presently, there is no well developed method of determining blood composition non-invasively. This projects hopes to use ultrasound and Doppler signals to evaluate the characteristic of hematocrit, the percentage by volume of red blood cells within whole blood. These non-invasive techniques may also be developed to be used on earth for trauma patients where invasive measure might be detrimental. Computational modeling is a useful tool for collecting preliminary information and predictions for the laboratory research. We hope to find and develop a computer program that will be able to simulate the ultrasound signals the project will work with. Simulated models of test conditions will more easily show what might be expected from laboratory results thus help the research group make informed decisions before and during experimentation. There are several existing Matlab based computer programs available, designed to interpret and simulate ultrasound signals. These programs will be evaluated to find which is best suited for the project needs. The criteria of evaluation that will be used are 1) the program must be able to specify transducer properties and specify transmitting and receiving signals, 2) the program must be able to simulate ultrasound signals through different attenuating mediums, 3) the program must be able to process moving targets in order to simulate the Doppler effects that are associated with blood flow, 4) the program should be user friendly and adaptable to various models. After a computer program is chosen, two simulation models will be constructed. These models will simulate and interpret an RF data signal and a Doppler signal.

  13. Non-Data Aided Doppler Shift Estimation for Underwater Acoustic Communication

    DTIC Science & Technology

    2014-05-01

    are presented. Keywords: Blind Doppler Shift Estimation, Underwater Communication, Autocorrelation, Power Spectral Density (PSD), Periodogram . I...Estimation, Underwater Communication, Autocorrelation, Power Spectral Density (PSD), Periodogram . 15. SUBJECT TERMS 16. SECURITY CLASSIFICATION OF: 17

  14. Spline function approximation for velocimeter Doppler frequency measurement

    NASA Technical Reports Server (NTRS)

    Savakis, Andreas E.; Stoughton, John W.; Kanetkar, Sharad V.

    1989-01-01

    A spline function approximation approach for measuring the Doppler spectral peak frequency in a laser Doppler velocimeter system is presented. The processor is designed for signal bursts with mean Doppler shift frequencies up to 100 MHz, input turbulence up to 20 percent, and photon counts as low as 300. The frequency-domain processor uses a bank of digital bandpass filters for the capture of the energy spectrum of each signal burst. The average values of the filter output energies, as a function of normalized frequency, are modeled as deterministic spline functions which are linearly weighted to evaluate the spectral peak location associated with the Doppler shift. The weighting coefficients are chosen to minimize the mean square error. Performance evaluation by simulation yields average errors in estimating mean Doppler frequencies within 0.5 percent for poor signal-to-noise conditions associated with a low photon count of 300 photons/burst.

  15. Christian Doppler is 200 years young.

    PubMed

    Bollinger, Alfred; Partsch, Hugo

    2003-11-01

    Christian Doppler was born 200 years ago in Salzburg, Austria, on November 29, 1803, worked in Prague and Vienna and died 150 years ago in Venice. In an article of eight pages he described the principle, which made him famous. It appeared in 1842 with the exotic title: "On the Coloured Light of the Double Stars and Certain Other Stars of the Heaven". The validity of his principle for velocity measurement was confirmed by trumpet sounds produced on a train moving towards and away from the observer. Around 1960 Japanese scientists suggested that flow velocity in blood vessels could be determined by analysing the difference of frequency between emitted and backscattered ultrasound. Rushmer and coworkers built machines suitable for medicine in Seattle, where Eugene Strandness recognized their potential and applied them in first studies. In 1967 the technique jumped to Europe and started to be used worldwide. Already by using continuous wave ultrasound it was possible to diagnose occlusive disease of neck and limb arteries, venous thrombosis and valvular insufficiency with accuracy. Measurements of postestenotic ankle blood pressure were facilitated by Doppler sensing. Over the years more sophisticated instruments were developed. Pulsed emission of ultrasound waves opened a way to study flow velocity profiles across large vessels. By combining the method with A or B mode ultrasound blood flow could be quantified and finally perfused segments of blood vessels visualized. Duplex scanning in its simple and then in its colour coded version is nowadays the standard non-invasive technique that nobody would like to miss. Vascular territories like intracranial, renal and intestinal arteries can also be explored. For the assessment of microvascular flow in skin and mucosae laser Doppler instruments were introduced.

  16. Christian Doppler and the Doppler effect

    NASA Astrophysics Data System (ADS)

    Toman, Kurt

    1984-04-01

    A summary is given of Doppler's life and career. He was born 180 years ago on November 29, 1803, in Salzburg, Austria. He died on March 17, 1853 in Venice. The effect bearing his name was first announced in a presentation before the Royal Bohemian Society of the Sciences in Prague on May 25, 1842. Doppler considered his work a generalization of the aberration theorem as discovered by Bradley. With it came the inference that the perception of physical phenomena can change with the state of motion of the observer. Acceptance of the principle was not without controversy. In 1852, the mathematician Petzval claimed that no useful scientific deductions can be made from Doppler's elementary equations. In 1860, Ernst Mach resolved the misunderstanding that clouded this controversy. The Doppler effect is alive and well. Its role in radio science and related disciplines is enumerated.

  17. [Myocardial function analysis with echocardiography-Doppler in septic shock].

    PubMed

    Fayssoil, A; Checinski, A

    2012-02-01

    Septic shock is a severe sepsis associated with cardio-circulatory failure and tissular hypoperfusion. Echocardiography-Doppler remains essential for the assessment of myocardial function in septic shock. This ultrasound procedure helps clinicians for the analysis of left ventricular systolic function, left ventricular diastolic function, right ventricular function and cardiac filling.

  18. History of intraoperative ultrasound.

    PubMed

    Makuuchi, M; Torzilli, G; Machi, J

    1998-11-01

    Intraoperative ultrasound (IOUS) using A-mode or non-real-time B-mode imaging started in the 1960s; however, it was not widely accepted mainly because of difficulty in image interpretation. In the late 1970s, IOUS became one of the topics in the surgical communities upon the introduction of high-frequency real-time B-mode ultrasound. Special probes for operative use were developed. In the 1980s, all over the world the use of IOUS spread to a variety of surgical fields, such as hepatobiliary pancreatic surgery, neurosurgery, and cardiovascular surgery. IOUS changed hepatic surgery dramatically because IOUS was the only modality that was capable of delineating and examining the interior of the liver during surgery. After 1990, color Doppler imaging and laparoscopic ultrasound were incorporated into IOUS. Currently, IOUS is considered an indispensable operative procedure for intraoperative decision-making and guidance of surgical procedures. For better surgical practice, education of surgeons in the use of ultrasound is the most important issue.

  19. Refining an Automated Transcranial Doppler System for the Detection of Vasospasm after Traumatic Brain Injury

    DTIC Science & Technology

    2014-09-01

    SUBJECT TERMS traumatic brain injury, ultrasound , transcranial Doppler, vasospasm. 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT 18...Presto’ that they have submitted to the FDA via a 510K for approval. Their system is based upon a novel and proprietary ultrasound platform along...within ultrasound -derived maps of blood flow speed captured by their device. This is reasonable because a view of each of the major cerebral arteries

  20. Advances in Doppler OCT

    PubMed Central

    Liu, Gangjun; Chen, Zhongping

    2014-01-01

    We review the principle and some recent applications of Doppler optical coherence tomography (OCT). The advances of the phase-resolved Doppler OCT method are described. Functional OCT algorithms which are based on an extension of the phase-resolved scheme are also introduced. Recent applications of Doppler OCT for quantification of flow, imaging of microvasculature and vocal fold vibration, and optical coherence elastography are briefly discussed. PMID:24443649

  1. Advanced Doppler tracking experiments

    NASA Technical Reports Server (NTRS)

    Armstrong, J. W.

    1989-01-01

    The Doppler tracking method is currently the only technique available for broadband gravitational wave searches in the approx. 10(exp -4) to 10(exp -1) Hz low frequency band. A brief review is given of the Doppler method, a discussion of the main noise sources, and a review of experience with current spacecraft and the prospects for sensitivity improvements in an advanced Doppler tracking experiment.

  2. 3D imaging options and ultrasound contrast agents for the ultrasound assessment of pediatric rheumatic patients.

    PubMed

    Madej, Tomasz

    2013-12-01

    The application of 3D imaging in pediatric rheumatology helps to make the assessment of inflammatory changes more objective and to estimate accurately their volume and the actual response to treatment in the course of follow-up examinations. Additional interesting opportunities are opened up by the vascularity analysis with the help of power Doppler and color Doppler in 3D imaging. Contrast-enhanced ultrasound examinations enable a more sensitive assessment of the vascularity of inflamed structures of the locomotor system, and a more accurate analysis of treatment's effect on changes in vascularity, and thereby the inflammation process activity, as compared to the classical options of power and color Doppler. The equipment required, time limitations, as well as the high price in the case of contrast-enhanced ultrasound, contribute to the fact that the 3D analysis of inflammatory changes and contrast-enhanced ultrasound examinations are not routinely applied for pediatric patients.

  3. Easy Pulsatile Phantom for Teaching and Validation of Flow Measurements in Ultrasound

    PubMed Central

    Rominger, M. B.; Müller-Stuler, E.-M.; Pinto, M.; Becker, A. S.; Martini, K.; Frauenfelder, T.; Klingmüller, V.

    2016-01-01

    Purpose: To build a simple model to teach and validate non-pulsatile and pulsatile flow quantification in ultrasound. Materials and Methods: The setting consists of the following connected components: (1) medical syringe pump producing an adjustable constant flow (ml/min), (2) modulator modifying constant flow to a reproducible pulsatile flow, (3) water tank containing a diagonal running silicone tube (0.5 mm inner diameter), and (4) a fixated ultrasound probe (L9 Linear Array 9 MHz, GE Logiq E9) measuring the flow inside the tube. Commercially available microbubbles suspended with physiological saline solution were used for ultrasonic visibility. Spectral Doppler of different flow profiles is performed. Results: The syringe pump produces an adjustable, constant flow and serves as the reference standard. The filling volume of the tube system is 1.2 ml. Microbubbles are very well detected by ultrasound and can be used as an easy and clean blood mimicking substance. The modulator generates different physiological and pathological flow profiles. Velocities are similar to those found within human blood vessels. Thus, it is possible to train and validate flow measurements in ultrasound. Conclusion: The model produces non-pulsatile and various pulsatile flow profiles and allows validation of flow measurements. The compact size permits easy and economic setup for flow measurements in research, skills lab and continuing education. PMID:27689183

  4. 3-D ultrafast Doppler imaging applied to the noninvasive mapping of blood vessels in vivo.

    PubMed

    Provost, Jean; Papadacci, Clement; Demene, Charlie; Gennisson, Jean-Luc; Tanter, Mickael; Pernot, Mathieu

    2015-08-01

    Ultrafast Doppler imaging was introduced as a technique to quantify blood flow in an entire 2-D field of view, expanding the field of application of ultrasound imaging to the highly sensitive anatomical and functional mapping of blood vessels. We have recently developed 3-D ultrafast ultrasound imaging, a technique that can produce thousands of ultrasound volumes per second, based on a 3-D plane and diverging wave emissions, and demonstrated its clinical feasibility in human subjects in vivo. In this study, we show that noninvasive 3-D ultrafast power Doppler, pulsed Doppler, and color Doppler imaging can be used to perform imaging of blood vessels in humans when using coherent compounding of 3-D tilted plane waves. A customized, programmable, 1024-channel ultrasound system was designed to perform 3-D ultrafast imaging. Using a 32 × 32, 3-MHz matrix phased array (Vermon, Tours, France), volumes were beamformed by coherently compounding successive tilted plane wave emissions. Doppler processing was then applied in a voxel-wise fashion. The proof of principle of 3-D ultrafast power Doppler imaging was first performed by imaging Tygon tubes of various diameters, and in vivo feasibility was demonstrated by imaging small vessels in the human thyroid. Simultaneous 3-D color and pulsed Doppler imaging using compounded emissions were also applied in the carotid artery and the jugular vein in one healthy volunteer.

  5. 3D Ultrafast Ultrasound Imaging In Vivo

    PubMed Central

    Provost, Jean; Papadacci, Clement; Arango, Juan Esteban; Imbault, Marion; Gennisson, Jean-Luc; Tanter, Mickael; Pernot, Mathieu

    2014-01-01

    Very high frame rate ultrasound imaging has recently allowed for the extension of the applications of echography to new fields of study such as the functional imaging of the brain, cardiac electrophysiology, and the quantitative real-time imaging of the intrinsic mechanical properties of tumors, to name a few, non-invasively and in real time. In this study, we present the first implementation of Ultrafast Ultrasound Imaging in three dimensions based on the use of either diverging or plane waves emanating from a sparse virtual array located behind the probe. It achieves high contrast and resolution while maintaining imaging rates of thousands of volumes per second. A customized portable ultrasound system was developed to sample 1024 independent channels and to drive a 32×32 matrix-array probe. Its capability to track in 3D transient phenomena occurring in the millisecond range within a single ultrafast acquisition was demonstrated for 3-D Shear-Wave Imaging, 3-D Ultrafast Doppler Imaging and finally 3D Ultrafast combined Tissue and Flow Doppler. The propagation of shear waves was tracked in a phantom and used to characterize its stiffness. 3-D Ultrafast Doppler was used to obtain 3-D maps of Pulsed Doppler, Color Doppler, and Power Doppler quantities in a single acquisition and revealed, for the first time, the complex 3-D flow patterns occurring in the ventricles of the human heart during an entire cardiac cycle, and the 3-D in vivo interaction of blood flow and wall motion during the pulse wave in the carotid at the bifurcation. This study demonstrates the potential of 3-D Ultrafast Ultrasound Imaging for the 3-D real-time mapping of stiffness, tissue motion, and flow in humans in vivo and promises new clinical applications of ultrasound with reduced intra- and inter-observer variability. PMID:25207828

  6. 3D ultrafast ultrasound imaging in vivo.

    PubMed

    Provost, Jean; Papadacci, Clement; Arango, Juan Esteban; Imbault, Marion; Fink, Mathias; Gennisson, Jean-Luc; Tanter, Mickael; Pernot, Mathieu

    2014-10-07

    Very high frame rate ultrasound imaging has recently allowed for the extension of the applications of echography to new fields of study such as the functional imaging of the brain, cardiac electrophysiology, and the quantitative imaging of the intrinsic mechanical properties of tumors, to name a few, non-invasively and in real time. In this study, we present the first implementation of Ultrafast Ultrasound Imaging in 3D based on the use of either diverging or plane waves emanating from a sparse virtual array located behind the probe. It achieves high contrast and resolution while maintaining imaging rates of thousands of volumes per second. A customized portable ultrasound system was developed to sample 1024 independent channels and to drive a 32  ×  32 matrix-array probe. Its ability to track in 3D transient phenomena occurring in the millisecond range within a single ultrafast acquisition was demonstrated for 3D Shear-Wave Imaging, 3D Ultrafast Doppler Imaging, and, finally, 3D Ultrafast combined Tissue and Flow Doppler Imaging. The propagation of shear waves was tracked in a phantom and used to characterize its stiffness. 3D Ultrafast Doppler was used to obtain 3D maps of Pulsed Doppler, Color Doppler, and Power Doppler quantities in a single acquisition and revealed, at thousands of volumes per second, the complex 3D flow patterns occurring in the ventricles of the human heart during an entire cardiac cycle, as well as the 3D in vivo interaction of blood flow and wall motion during the pulse wave in the carotid at the bifurcation. This study demonstrates the potential of 3D Ultrafast Ultrasound Imaging for the 3D mapping of stiffness, tissue motion, and flow in humans in vivo and promises new clinical applications of ultrasound with reduced intra--and inter-observer variability.

  7. 3D ultrafast ultrasound imaging in vivo

    NASA Astrophysics Data System (ADS)

    Provost, Jean; Papadacci, Clement; Esteban Arango, Juan; Imbault, Marion; Fink, Mathias; Gennisson, Jean-Luc; Tanter, Mickael; Pernot, Mathieu

    2014-10-01

    Very high frame rate ultrasound imaging has recently allowed for the extension of the applications of echography to new fields of study such as the functional imaging of the brain, cardiac electrophysiology, and the quantitative imaging of the intrinsic mechanical properties of tumors, to name a few, non-invasively and in real time. In this study, we present the first implementation of Ultrafast Ultrasound Imaging in 3D based on the use of either diverging or plane waves emanating from a sparse virtual array located behind the probe. It achieves high contrast and resolution while maintaining imaging rates of thousands of volumes per second. A customized portable ultrasound system was developed to sample 1024 independent channels and to drive a 32  ×  32 matrix-array probe. Its ability to track in 3D transient phenomena occurring in the millisecond range within a single ultrafast acquisition was demonstrated for 3D Shear-Wave Imaging, 3D Ultrafast Doppler Imaging, and, finally, 3D Ultrafast combined Tissue and Flow Doppler Imaging. The propagation of shear waves was tracked in a phantom and used to characterize its stiffness. 3D Ultrafast Doppler was used to obtain 3D maps of Pulsed Doppler, Color Doppler, and Power Doppler quantities in a single acquisition and revealed, at thousands of volumes per second, the complex 3D flow patterns occurring in the ventricles of the human heart during an entire cardiac cycle, as well as the 3D in vivo interaction of blood flow and wall motion during the pulse wave in the carotid at the bifurcation. This study demonstrates the potential of 3D Ultrafast Ultrasound Imaging for the 3D mapping of stiffness, tissue motion, and flow in humans in vivo and promises new clinical applications of ultrasound with reduced intra—and inter-observer variability.

  8. Abdominal ultrasound

    MedlinePlus

    ... Kidney - blood and urine flow Abdominal ultrasound References Chen L. Abdominal ultrasound imaging. In: Sahani DV, Samir ... the Health on the Net Foundation (www.hon.ch). The information provided herein should not be used ...

  9. Endoscopic ultrasound

    MedlinePlus

    ... page: //medlineplus.gov/ency/article/007646.htm Endoscopic ultrasound To use the sharing features on this page, please enable JavaScript. Endoscopic ultrasound is a type of imaging test. It is ...

  10. Thyroid ultrasound

    PubMed Central

    Chaudhary, Vikas; Bano, Shahina

    2013-01-01

    Thyroid ultrasonography has established itself as a popular and useful tool in the evaluation and management of thyroid disorders. Advanced ultrasound techniques in thyroid imaging have not only fascinated the radiologists but also attracted the surgeons and endocrinologists who are using these techniques in their daily clinical and operative practice. This review provides an overview of indications for ultrasound in various thyroid diseases, describes characteristic ultrasound findings in these diseases, and illustrates major diagnostic pitfalls of thyroid ultrasound. PMID:23776892

  11. Carotid Ultrasound

    MedlinePlus

    ... this page from the NHLBI on Twitter. Carotid Ultrasound Also known as carotid duplex. Carotid ultrasound is a painless imaging test that uses high- ... of your carotid arteries. This test uses an ultrasound machine, which includes a computer, a screen, and ...

  12. [Liver ultrasound: focal lesions and diffuse diseases].

    PubMed

    Segura Grau, A; Valero López, I; Díaz Rodríguez, N; Segura Cabral, J M

    2016-01-01

    Liver ultrasound is frequently used as a first-line technique for the detection and characterization of the most common liver lesions, especially those incidentally found focal liver lesions, and for monitoring of chronic liver diseases. Ultrasound is not only used in the Bmode, but also with Doppler and, more recently, contrast-enhanced ultrasound. It is mainly used in the diagnosis of diffuse liver diseases, such as steatosis or cirrhosis. This article presents a practical approach for diagnosis workup, in which the different characteristics of the main focal liver lesions and diffuse liver diseases are reviewed.

  13. The Cognitive Doppler.

    ERIC Educational Resources Information Center

    Kozoil, Micah E.

    1989-01-01

    Discusses the learning needs of students in the concrete operational stage in mathematics. Identifies the phenomenon of reduced cognitive performance in an out-of-class environment as the "Cognitive Doppler." Suggests methods of reducing the pronounced effects of the Cognitive Doppler by capitalizing on the students' ability to memorize…

  14. The EVE Doppler Sensitivity and Flare Observations

    NASA Technical Reports Server (NTRS)

    Hudson, H. S.; Woods, T. N.; Chamberlin, P. C.; Didkovsky, L.; Del Zanna, G.

    2011-01-01

    The Extreme-ultraviolet Variability Experiment (EVE) obtains continuous EUV spectra of the Sun viewed as a star. Its primary objective is the characterization of solar spectral irradiance, but its sensitivity and stability make it extremely interesting for observations of variability on time scales down to the limit imposed by its basic 10 s sample interval. In this paper we characterize the Doppler sensitivity of the EVE data. We find that the 30.4 nm line of He II has a random Doppler error below 0.001 nm (1 pm, better than 10 km/s as a redshift), with ample stability to detect the orbital motion of its satellite, the Solar Dynamics Observatory (SDO). Solar flares also displace the spectrum, both because of Doppler shifts and because of EVE's optical layout, which (as with a slitless spectrograph) confuses position and wavelength. As a flare develops, the centroid of the line displays variations that reflect Doppler shifts and therefore flare dynamics. For the impulsive phase of the flare SOL2010-06-12, we find the line centroid to have a redshift of 16.8 +/- 5.9 km/s relative to that of the flare gradual phase (statistical errors only). We find also that high-temperature lines, such as Fe XXIV 19.2 nm, have well-determined Doppler components for major flares, with decreasing apparent blueshifts as expected from chromospheric evaporation flows.

  15. Rotational Doppler effect in x-ray photoionization

    SciTech Connect

    Sun Yuping; Wang Chuankui; Gel'mukhanov, Faris

    2010-11-15

    The energy of the photoelectron experiences a red or blue Doppler shift when the molecule recedes from the detector or approaches him. This results in a broadening of the photoelectron line due to the translational thermal motion. However, the molecules also have rotational degrees of freedom and we show that the translational Doppler effect has its rotational counterpart. This rotational Doppler effect leads to an additional broadening of the spectral line of the same magnitude as the Doppler broadening caused by translational thermal motion. The rotational Doppler broadening as well as the rotational recoil broadening is sensitive to the molecular orbital from which the photoelectron is ejected. This broadening should be taken into account in analysis of x-ray photoemission spectra of super-high resolution and it can be directly observed using x-ray pump-probe spectroscopy.

  16. A New Active Cavitation Mapping Technique for Pulsed HIFU Applications – Bubble Doppler

    PubMed Central

    Li, Tong; Khokhlova, Tatiana; Sapozhnikov, Oleg; Hwang, Joo Ha; Sapozhnikov, Oleg; O’Donnell, Matthew

    2015-01-01

    In this work, a new active cavitation mapping technique for pulsed high-intensity focused ultrasound (pHIFU) applications termed bubble Doppler is proposed and its feasibility tested in tissue-mimicking gel phantoms. pHIFU therapy uses short pulses, delivered at low pulse repetition frequency, to cause transient bubble activity that has been shown to enhance drug and gene delivery to tissues. The current gold standard for detecting and monitoring cavitation activity during pHIFU treatments is passive cavitation detection (PCD), which provides minimal information on the spatial distribution of the bubbles. B-mode imaging can detect hyperecho formation, but has very limited sensitivity, especially to small, transient microbubbles. The bubble Doppler method proposed here is based on a fusion of the adaptations of three Doppler techniques that had been previously developed for imaging of ultrasound contrast agents – color Doppler, pulse inversion Doppler, and decorrelation Doppler. Doppler ensemble pulses were interleaved with therapeutic pHIFU pulses using three different pulse sequences and standard Doppler processing was applied to the received echoes. The information yielded by each of the techniques on the distribution and characteristics of pHIFU-induced cavitation bubbles was evaluated separately, and found to be complementary. The unified approach - bubble Doppler – was then proposed to both spatially map the presence of transient bubbles and to estimate their sizes and the degree of nonlinearity. PMID:25265178

  17. Doppler radar flowmeter

    DOEpatents

    Petlevich, Walter J.; Sverdrup, Edward F.

    1978-01-01

    A Doppler radar flowmeter comprises a transceiver which produces an audio frequency output related to the Doppler shift in frequency between radio waves backscattered from particulate matter carried in a fluid and the radiated radio waves. A variable gain amplifier and low pass filter are provided for amplifying and filtering the transceiver output. A frequency counter having a variable triggering level is also provided to determine the magnitude of the Doppler shift. A calibration method is disclosed wherein the amplifier gain and frequency counter trigger level are adjusted to achieve plateaus in the output of the frequency counter and thereby allow calibration without the necessity of being able to visually observe the flow.

  18. A brief history of ultrasound in rheumatology: where we were.

    PubMed

    Grassi, Walter; Filippucci, Emilio

    2014-01-01

    Ultrasonography in the '70s was a well-known and widely used method within several medical specialties but not in rheumatology. Initial development of the field was led by radiologists who mainly investigated the potential of ultrasound in the assessment of large joints. In the late '80s, the first studies supporting the role of ultrasound in the detection of soft tissue changes and bone erosions in the hands of patients with rheumatoid arthritis were published. In the '90s, the dramatic improvement of spatial resolution due to the new generation high frequency probes opened up new avenues for the exploration of otherwise undetectable anatomical details. Ultrasound research during this period was enhanced by the growing use of colour Doppler and power Doppler and by the first prototypes of three dimensional ultrasound. Over the last 10 years, the buzz words in ultrasound research in rheumatology have been standardisation, early diagnosis and therapy monitoring.

  19. Ultrasound physics.

    PubMed

    Shriki, Jesse

    2014-01-01

    Bedside ultrasound has become an important modality for obtaining critical information in the acute care of patients. It is important to understand the physics of ultrasound in order to perform and interpret images at the bedside. The physics of both continuous wave and pulsed wave sound underlies diagnostic ultrasound. The instrumentation, including transducers and image processing, is important in the acquisition of appropriate sonographic images. Understanding how these concepts interplay with each other enables practitioners to obtain the best possible images.

  20. Doppler Lidar (DL) Handbook

    SciTech Connect

    Newsom, RK

    2012-02-13

    The Doppler lidar (DL) is an active remote sensing instrument that provides range- and time-resolved measurements of radial velocity and attenuated backscatter. The principle of operation is similar to radar in that pulses of energy are transmitted into the atmosphere; the energy scattered back to the transceiver is collected and measured as a time-resolved signal. From the time delay between each outgoing transmitted pulse and the backscattered signal, the distance to the scatterer is inferred. The radial or line-of-sight velocity of the scatterers is determined from the Doppler frequency shift of the backscattered radiation. The DL uses a heterodyne detection technique in which the return signal is mixed with a reference laser beam (i.e., local oscillator) of known frequency. An onboard signal processing computer then determines the Doppler frequency shift from the spectra of the heterodyne signal. The energy content of the Doppler spectra can also be used to determine attenuated backscatter.

  1. A hand-held ultrasound machine vs. conventional ultrasound machine in the bedside assessment of post-liver transplant patients.

    PubMed

    Trinquart, Ludovic; Bruno, Onorina; Angeli, Maria Luigia; Belghiti, Jacques; Chatellier, Gilles; Vilgrain, Valérie

    2009-10-01

    The purpose was to assess the diagnostic accuracy of a hand-held Doppler ultrasound (US) machine for the bedside detection of liver and vascular abnormalities after liver transplantation in the intensive care unit. The IRB approved this study, and written informed consent was obtained from all patients or the patient's legal representative. Any liver transplant recipient at our institution who needed a bedside Doppler US examination in the intensive care unit was eligible. Patients underwent routine grey-scale, colour, and spectral Doppler US examinations of the liver with a conventional machine, which was taken as the reference method, and with a hand-held machine on the same day. Examinations followed one another and were performed in a blinded fashion by two radiologists. Over a 4-month period, 24 consecutive patients (16 men, median age 54 years old; 16 cadaveric and 8 living related right liver transplantations) underwent 43 examinations with both conventional and hand-held machines. Image quality and overall satisfaction scores of grey-scale were lower with the hand-held than with the conventional machine. The hand-held was similar to the conventional machine for assessing the patency of portal veins, hepatic veins and the IVC in all patients but one. The hand-held machine failed to detect signals in the right branch of the hepatic artery and in the hilum in two and one cases, respectively. There was no abnormal hepatic arterial flow with the conventional machine in any of the patients, and the results were the same with the hand-held machine. Total examination time was significantly longer with the hand-held machine. The hand-held US machine had a high diagnostic accuracy for both parenchymal and vascular analyses compared with a conventional US machine in the bedside assessment of post-liver transplant patients.

  2. Role of contrast-enhanced ultrasound (CEUS) in the diagnosis of endometrial pathology

    PubMed Central

    POP, CIPRIAN MIHAITA; MIHU, DAN; BADEA, RADU

    2015-01-01

    Ultrasound is the reference imaging procedure used for the exploration of endometrial pathology. As medical procedures improve and the requirements of modern medicine become more demanding, gray-scale ultrasound is insufficient in establishing gynecological diagnosis. Thus, more complex examination techniques are required: Doppler ultrasound, contrast-enhanced ultrasound (CEUS), 3D ultrasound, etc. Contrast-enhanced ultrasound is a special examination technique that gains more and more ground. This allows a detailed real-time evaluation of microcirculation in a certain territory, which is impossible to perform by Doppler ultrasound. The aim of this review is to synthesize current knowledge regarding CEUS applications in endometrial pathology, to detail the technical aspects of endometrial CEUS and the physical properties of the equipment and contrast agents used, as well as to identify the limitations of the method. PMID:26733740

  3. Assessment of parathyroid glands in hemodialysis patients by using color Doppler sonography.

    PubMed

    Ozcan, Umit Aksoy; Oktay, Ilay

    2009-11-01

    The aim of this study was to assess the role of color and spectral Doppler ultrasound (CDU) in the evaluation of enlarged parathyroid glands in hemodialysis patients with secondary hyperparathyroidism. Fourteen hemodialysis patients with elevated intact parathyroid hormone (iPTH) levels were evaluated prospectively with CDU. The volume of each observed parathyroid gland and the spectral CDU data (velocities, resistance and pulsatility indices, systolic to diastolic ratio, and flow volume output (FVO)) were noted. The biochemical data (iPTH, calcium, phosphate levels), and CDU results were analyzed with the Spearman correlation test. Two patients were excluded, and 27 enlarged parathyroid glands were observed in 12 patients. The mean total volume of enlarged parathyroid glands per patient was 1.95 cm(3) (0.06-5.5 cm(3)). Arterial supply was demonstrated in 78% (21/27) of enlarged parathyroid glands. Mean total FVO of enlarged glands per patient was 238.5 ml/min (620-0 ml/min) and mean iPTH level was 1,477 pg/ml (643-3,132 pg/ml). The positive correlations of total volume (p = 0.022), iPTH (p = 0.024), and FVO (p = 0.022) were statistically significant. In secondary hyperparathyroidism, total volume of the visualized enlarged parathyroid glands and the total of FVOs per patient are positively correlated with iPTH levels which may help clinical management and follow-up of end-stage renal disease patients.

  4. 3-D Ultrafast Doppler Imaging Applied to the Noninvasive and Quantitative Imaging of Blood Vessels in Vivo

    PubMed Central

    Provost, J.; Papadacci, C.; Demene, C.; Gennisson, J-L.; Tanter, M.; Pernot, M.

    2016-01-01

    Ultrafast Doppler Imaging was introduced as a technique to quantify blood flow in an entire 2-D field of view, expanding the field of application of ultrasound imaging to the highly sensitive anatomical and functional mapping of blood vessels. We have recently developed 3-D Ultrafast Ultrasound Imaging, a technique that can produce thousands of ultrasound volumes per second, based on three-dimensional plane and diverging wave emissions, and demonstrated its clinical feasibility in human subjects in vivo. In this study, we show that non-invasive 3-D Ultrafast Power Doppler, Pulsed Doppler, and Color Doppler Imaging can be used to perform quantitative imaging of blood vessels in humans when using coherent compounding of three-dimensional tilted plane waves. A customized, programmable, 1024-channel ultrasound system was designed to perform 3-D Ultrafast Imaging. Using a 32X32, 3-MHz matrix phased array (Vermon, France), volumes were beamformed by coherently compounding successive tilted plane wave emissions. Doppler processing was then applied in a voxel-wise fashion. 3-D Ultrafast Power Doppler Imaging was first validated by imaging Tygon tubes of varying diameter and its in vivo feasibility was demonstrated by imaging small vessels in the human thyroid. Simultaneous 3-D Color and Pulsed Doppler Imaging using compounded emissions were also applied in the carotid artery and the jugular vein in one healthy volunteer. PMID:26276956

  5. Contrast-enhanced power Doppler US in the diagnosis of renal pseudotumors.

    PubMed

    Ascenti, G; Zimbaro, G; Mazziotti, S; Gaeta, M; Lamberto, S; Scribano, E

    2001-01-01

    The term "pseudotumor" is used to refer to several anatomic variants that can simulate a renal mass, the most frequent of which are hypertrophied column of Bertin, persistence of fetal lobation, and the dromedary or splenic hump. We describe the findings of power Doppler US after the ultrasound contrast agent (Levovist, Schering, Berlin, Germany) administration in 4 patients with a renal focal lesion in whom gray-scale and baseline power Doppler US was not able to certainly differentiate pseudotumor from neoplasm.

  6. High-overtone Self-Focusing Acoustic Transducers for High Frequency Ultrasonic Doppler

    PubMed Central

    Zhu, Jie; Lee, Chuangyuan; Kim, Eun Sok; Wu, Dawei; Hu, Changhong; Zhou, Qifa; Shung, K. Kirk.; Wang, Gaofeng; Yu, Hongyu

    2010-01-01

    This work reports the potential use of high-overtone self-focusing acoustic transducers for high frequency ultrasonic Doppler. By using harmonic frequencies of a thick bulk Lead Zirconate Titanate (PZT) transducer with a novel air-reflector Fresnel lens, we obtained strong ultrasound signals at 60 MHz (3rd harmonic) and 100 MHz (5th harmonic). Both experimental and theoretical analysis has demonstrated that the transducers can be applied to Doppler systems with high frequencies up to 100 MHz. PMID:20206371

  7. Data analysis techniques: Spectral processing

    NASA Technical Reports Server (NTRS)

    Strauch, R. G.

    1983-01-01

    The individual steps in the data processing scheme applied to most radars used for wind sounding are analyzed. This processing method uses spectral analysis and assumes a pulse Doppler radar. Improvement in the signal to noise ratio of some radars is discussed.

  8. [Color-Doppler semiology in transplanted kidney].

    PubMed

    Rivolta, R; Castagnone, D; Burdick, L; Mandelli, C; Mangiarotti, R

    1993-05-01

    Color-encoded duplex ultrasonography (CEDU) makes a more accurate technique in kidney graft monitoring by combining real-time US with pulsed Doppler studies of renal vasculature. It is a non-invasive and easy technique. Suitable to study the whole renal artery and vein, CEDU also allows the qualitative and quantitative assessment of the intrarenal vasculature and therefore the easy diagnosis of such vessel dysfunctions as arteriovenous fistulas following biopsy. Moreover, Doppler spectral analysis can be used to distinguish among different causes of renal allograft dysfunction--i.e. rejection, cyclosporine nephrotoxicity or acute tubular necrosis. The value of the resistive index for the differential diagnosis is discussed. CEDU allows a more reliable measurement of renal blood flow thanks to the more precise evaluation of renal artery diameter and mean flow velocity.

  9. Ultrasound -- Vascular

    MedlinePlus

    ... plan for their effective treatment. detect blood clots (deep venous thrombosis (DVT) in the major veins of ... What are the limitations of Vascular Ultrasound? Vessels deep in the body are harder to see than ...

  10. Trauma Ultrasound.

    PubMed

    Wongwaisayawan, Sirote; Suwannanon, Ruedeekorn; Prachanukool, Thidathit; Sricharoen, Pungkava; Saksobhavivat, Nitima; Kaewlai, Rathachai

    2015-10-01

    Ultrasound plays a pivotal role in the evaluation of acute trauma patients through the use of multi-site scanning encompassing abdominal, cardiothoracic, vascular and skeletal scans. In a high-speed polytrauma setting, because exsanguinations are the primary cause of trauma morbidity and mortality, ultrasound is used for quick and accurate detection of hemorrhages in the pericardial, pleural, and peritoneal cavities during the primary Advanced Trauma Life Support (ATLS) survey. Volume status can be assessed non-invasively with ultrasound of the inferior vena cava (IVC), which is a useful tool in the initial phase and follow-up evaluations. Pneumothorax can also be quickly detected with ultrasound. During the secondary survey and in patients sustaining low-speed or localized trauma, ultrasound can be used to help detect abdominal organ injuries. This is particularly helpful in patients in whom hemoperitoneum is not identified on an initial scan because findings of organ injuries will expedite the next test, often computed tomography (CT). Moreover, ultrasound can assist in detection of fractures easily obscured on radiography, such as rib and sternal fractures.

  11. Finnish Meteorological Institute Doppler Lidar

    SciTech Connect

    Ewan OConnor

    2015-03-27

    This doppler lidar system provides co-polar and cross polar attenuated backscatter coefficients,signal strength, and doppler velocities in the cloud and in the boundary level, including uncertainties for all parameters. Using the doppler beam swinging DBS technique, and Vertical Azimuthal Display (VAD) this system also provides vertical profiles of horizontal winds.

  12. The Doppler Pendulum Experiment

    ERIC Educational Resources Information Center

    Lee, C. K.; Wong, H. K.

    2011-01-01

    An experiment to verify the Doppler effect of sound waves is described. An ultrasonic source is mounted at the end of a simple pendulum. As the pendulum swings, the rapid change of frequency can be recorded by a stationary receiver using a simple frequency-to-voltage converter. The experimental results are in close agreement with the Doppler…

  13. Doppler wind profile experiment

    NASA Technical Reports Server (NTRS)

    Arnold, J. E.

    1985-01-01

    The data collection phase of a Doppler wind measurement experiment supported by high-resolution Jimsphere/FPS-16 wind data and Windsonde data was carried out at the Kennedy Space Center in February, March and early April of 1985. The Doppler wind measurements were made using a hybrid doppler profiler put in place by the Johnson Space Center and a SOUSY profiler operated by Radian Corporation. Both systems operated at 50 Mhz. Although the doppler profiler systems were located 10 km apart to enable concurrent operation of the systems for data comparison, little concurrent data were obtained due to set-up delays with the SOUSY system, and system problems with the WPL system during the last month of the test. During the test period, special serial Jimsphere soundings were taken at two-hour intervals on six days in March and April in addition to balloon soundings taken in support of the Shuttle launch operations. In addition, there is temperature, moisture and wind information available from the daily morning Radiosonde sounding taken at the Kennedy site. The balloon release point was at the same location as the SOUSY profiler. Vertical resolution of the SOUSY profiler was 150 M to approximately 20 km. The vertical resolution of the WPL profiler was 290 M to 10 km and 870 M to 17 km. Winds determined form the Jimsphere balloon have a vertical resolution of 30 M.

  14. Hybrid ultrasound imaging techniques (fusion imaging).

    PubMed

    Sandulescu, Daniela Larisa; Dumitrescu, Daniela; Rogoveanu, Ion; Saftoiu, Adrian

    2011-01-07

    Visualization of tumor angiogenesis can facilitate non-invasive evaluation of tumor vascular characteristics to supplement the conventional diagnostic imaging goals of depicting tumor location, size, and morphology. Hybrid imaging techniques combine anatomic [ultrasound, computed tomography (CT), and/or magnetic resonance imaging (MRI)] and molecular (single photon emission CT and positron emission tomography) imaging modalities. One example is real-time virtual sonography, which combines ultrasound (grayscale, colour Doppler, or dynamic contrast harmonic imaging) with contrast-enhanced CT/MRI. The benefits of fusion imaging include an increased diagnostic confidence, direct comparison of the lesions using different imaging modalities, more precise monitoring of interventional procedures, and reduced radiation exposure.

  15. Carotid Ultrasound Imaging

    MedlinePlus

    ... Index A-Z Ultrasound - Carotid Carotid ultrasound uses sound waves to produce pictures of the carotid arteries ... pictures of the inside of the body using sound waves. Ultrasound imaging, also called ultrasound scanning or ...

  16. The TiO c1Φ- a1Δ (0-0) Band at Sub-Doppler Spectral Resolution: Spin-Orbit Interactions in the cState

    NASA Astrophysics Data System (ADS)

    Amiot, C.; Cheikh, M.; Luc, P.; Vetter, R.

    1996-09-01

    The c1Φ- a1Δ (0-0) band of titanium monoxide has been studied at sub-Doppler resolution by crossing a beam of TiO molecules with a cw tunable laser beam and collecting the laser-induced fluorescence. The rotational structures of the P, Q, and Rbranches have been observed up to rotational quantum numbers equal to 52, 94, and 96, respectively. The spectroscopic data have been reduced to a set of 11 effective molecular constants with a root mean squared values of the residuals equal to 7 × 10 -4cm -1. However, the necessity of including seventh order terms in the rotational development of the energy put into evidence a very strong spin-orbit interaction between the c1Φ ( v= 0) and C3Δ 3( v= 2 and v= 3) levels. The derived spin-orbit parameter allows for the reproduction of the measured wavenumbers without the introduction of higher order rotational terms into the energy development. The value of the spin-orbit parameter indicates the necessity of revisiting the configuration scheme of the involved electronic states.

  17. [Use of ultrasound in ophthalmology].

    PubMed

    Trier, H G

    1982-12-01

    In ophthalmology, ultrasound is applied in diagnostics as well as in surgery and therapy. This paper gives a short survey on both applications. Ultrasonic phacoemulsification is of considerable practical importance for modern cataract micro-surgery with intraocular lens implantation. Applications of that kind require consideration of ultrasonic bioeffects and equipment safety. Diagnostic use of ultrasound includes biometry (echometry), tissue examination and characterization, and vascular investigations in eye and orbit. The application of diagnostic ultrasound on in-patients, its individual indications, and the appropriate methods (A, B, automatic biometric devices for axial length measuring, M, Doppler) are described. Examples of commercially available instruments for the different applications are given. In comparison with other disciplines ophthalmic A-mode and B-mode echography is characterized by: refined depth resolution and lateral resolution; the important part of quantitative methods for clinical evaluation of echograms; and the advanced level of quality assurance for equipment performance. Refined tissue evaluation requires optimized and reproducible equipment parameters. To ensure these conditions the clinical echographer must be educated and willing to test performance and quality of his equipment. Finally, a perspective of actual research in diagnostic ultrasound of the eye is given.

  18. Role of ultrasound in colorectal diseases

    PubMed Central

    Bor, Renáta; Fábián, Anna; Szepes, Zoltán

    2016-01-01

    Ultrasound is an undervalued non-invasive examination in the diagnosis of colonic diseases. It has been replaced by the considerably more expensive magnetic resonance imaging and computed tomography, despite the fact that, as first examination, it can usefully supplement the diagnostic process. Transabdominal ultrasound can provide quick information about bowel status and help in the choice of adequate further examinations and treatment. Ultrasonography, as a screening imaging modality in asymptomatic patients can identify several colonic diseases such as diverticulosis, inflammatory bowel disease or cancer. In addition, it is widely available, cheap, non-invasive technique without the use of ionizing radiation, therefore it is safe to use in childhood or during pregnancy, and can be repeated at any time. New ultrasound techniques such as elastography, contrast enhanced and Doppler ultrasound, mini-probes rectal and transperineal ultrasonography have broadened the indication. It gives an overview of the methodology of various ultrasound examinations, presents the morphology of normal bowel wall and the typical changes in different colonic diseases. We will pay particular attention to rectal and transperineal ultrasound because of their outstanding significance in the diagnosis of rectal and perineal disorders. This article seeks to overview the diagnostic impact and correct indications of bowel ultrasound. PMID:27920469

  19. Dispersed single-phase-step Michelson interferometer for Doppler imaging using sunlight.

    PubMed

    Wan, Xiaoke; Ge, Jian

    2012-09-15

    A Michelson interferometer is dispersed with a fiber array-fed spectrograph, providing 59 Doppler sensing channels using sunlight in the 510-570 nm wavelength region. The interferometer operates at a single-phase-step mode, which is particularly advantageous in multiplexing and data processing compared to the phase-stepping mode of other interferometer spectrometer instruments. Spectral templates are prepared using a standard solar spectrum and simulated interferometer modulations, such that the correlation function with a measured 1D spectrum determines the Doppler shift. Doppler imaging of a rotating cylinder is demonstrated. The average Doppler sensitivity is ~12 m/s, with some channels reaching ~5 m/s.

  20. Doppler effect in optical velocimetry

    NASA Astrophysics Data System (ADS)

    Rinkevichius, Bronius S.

    1996-02-01

    The current state of the optical metrology based on the Doppler effect has been reviewed. Some historical and scientific information is given, in addition the contemporary optical methods of the velocity measurement using the Doppler effect are analyzed. The Doppler effect applications in astrophysics, plasma physics, investigations of gas and liquid flows, acoustics, mechanics of the deforming solid body and of the rotational motion are considered. The description is presented for the following techniques of the velocity measurement: laser Doppler anemometry, laser Doppler vibrometry, laser gyroscopy.

  1. Early Detection of Ovarian Cancer by Tumor Epithelium-Targeted Molecular Ultrasound

    DTIC Science & Technology

    2013-10-01

    were examined. 3. Archived ultrasound images were examined off-line, ovarian tumor associated changes in gray scale intensity and Doppler indices...tumor was selected and the average image intensity (in pixel values) was determined using 7 Figure 1: Enhancement of ultrasound signal intensity ...16 targeted imaging agents increased ultrasound signal intensity remarkably in post-targeted imaging. The tumor showed septa of tissue mass during

  2. Laser Doppler anemometry

    NASA Technical Reports Server (NTRS)

    Johnson, Dennis A.

    1988-01-01

    The material in this NASA TM is to appear as a chapter on Laser Doppler Anemometry (LDA) in the AGARDograph entitled, A Survey of Measurements and Measuring Techniques in Rapidly Distorted Compressible Turbulent Boundary Layers. The application of LDA (specifically, the dual-beam, burst-counter approach) to compressible flows is discussed. Subjects treated include signal processing, particle light scattering and tracking, data reduction and sampling bias, and three-dimensional measurements.

  3. Doppler Optical Coherence Tomography

    PubMed Central

    Leitgeb, Rainer A.; Werkmeister, René M.; Blatter, Cedric; Schmetterer, Leopold

    2014-01-01

    Optical Coherence Tomography (OCT) has revolutionized ophthalmology. Since its introduction in the early 1990s it has continuously improved in terms of speed, resolution and sensitivity. The technique has also seen a variety of extensions aiming to assess functional aspects of the tissue in addition to morphology. One of these approaches is Doppler OCT (DOCT), which aims to visualize and quantify blood flow. Such extensions were already implemented in time domain systems, but have gained importance with the introduction of Fourier domain OCT. Nowadays phase-sensitive detection techniques are most widely used to extract blood velocity and blood flow from tissues. A common problem with the technique is that the Doppler angle is not known and several approaches have been realized to obtain absolute velocity and flow data from the retina. Additional studies are required to elucidate which of these techniques is most promising. In the recent years, however, several groups have shown that data can be obtained with high validity and reproducibility. In addition, several groups have published values for total retinal blood flow. Another promising application relates to non-invasive angiography. As compared to standard techniques such as fluorescein and indocyanine-green angiography the technique offers two major advantages: no dye is required and depth resolution is required is provided. As such Doppler OCT has the potential to improve our abilities to diagnose and monitor ocular vascular diseases. PMID:24704352

  4. Laser double Doppler flowmeter

    NASA Astrophysics Data System (ADS)

    Poffo, L.; Goujon, J.-M.; Le Page, R.; Lemaitre, J.; Guendouz, M.; Lorrain, N.; Bosc, D.

    2014-05-01

    The Laser Doppler flowmetry (LDF) is a non-invasive method for estimating the tissular blood flow and speed at a microscopic scale (microcirculation). It is used for medical research as well as for the diagnosis of diseases related to circulatory system tissues and organs including the issues of microvascular flow (perfusion). It is based on the Doppler effect, created by the interaction between the laser light and tissues. LDF measures the mean blood flow in a volume formed by the single laser beam, that penetrate into the skin. The size of this measurement volume is crucial and depends on skin absorption, and is not directly reachable. Therefore, current developments of the LDF are focused on the use of always more complex and sophisticated signal processing methods. On the other hand, laser Double Doppler Flowmeter (FL2D) proposes to use two laser beams to generate the measurement volume. This volume would be perfectly stable and localized at the intersection of the two laser beams. With FL2D we will be able to determine the absolute blood flow of a specific artery. One aimed application would be to help clinical physicians in health care units.

  5. Investigation of Ultrasound-Measured Flow Velocity, Flow Rate and Wall Shear Rate in Radial and Ulnar Arteries Using Simulation.

    PubMed

    Zhou, Xiaowei; Xia, Chunming; Stephen, Gandy; Khan, Faisel; Corner, George A; Hoskins, Peter R; Huang, Zhihong

    2017-02-21

    Parameters of blood flow measured by ultrasound in radial and ulnar arteries, such as flow velocity, flow rate and wall shear rate, are widely used in clinical practice and clinical research. Investigation of these measurements is useful for evaluating accuracy and providing knowledge of error sources. A method for simulating the spectral Doppler ultrasound measurement process was developed with computational fluid dynamics providing flow-field data. Specific scanning factors were adjusted to investigate their influence on estimation of the maximum velocity waveform, and flow rate and wall shear rate were derived using the Womersley equation. The overestimation in maximum velocity increases greatly (peak systolic from about 10% to 30%, time-averaged from about 30% to 50%) when the beam-vessel angle is changed from 30° to 70°. The Womersley equation was able to estimate flow rate in both arteries with less than 3% error, but performed better in the radial artery (2.3% overestimation) than the ulnar artery (15.4% underestimation) in estimating wall shear rate. It is concluded that measurements of flow parameters in the radial and ulnar arteries with clinical ultrasound scanners are prone to clinically significant errors.

  6. Velocity variability in ultrasonic Doppler examinations.

    PubMed

    Hadlock, Jean; Beach, Kirk W

    2009-06-01

    Ultrasonic Doppler examination with spectral waveform has been used for the classification and surveillance of carotid artery stenosis for over 25 years. Progression/regression between examinations can be identified with 95% confidence if the velocity measurements change by more than two times the root mean square difference (RMSD) of the repeat measurement. Peak systolic velocity and end diastolic velocity measurements at a Doppler angle of 60 degrees were repeated in 47 carotid examinations. Measurement difference between sonographers and between instruments was tabulated. Root mean square difference was 11 cm/s (RMS%D = 11%) for systolic and 7 cm/s (RMS%D = 21%) for diastolic velocity measurements (excluding one severe stenosis case). Results for differences between sonographers and between instruments were similar to the overall results. In serial arterial studies using this Doppler velocimetry method, a difference exceeding 23 cm/s (21%) systolic, or 14 cm/s (42%) diastolic velocity indicates a significant (2 x RMSD) hemodynamic change.

  7. Cerebral Lateralization and General Intelligence: Gender Differences in a Transcranial Doppler Study

    ERIC Educational Resources Information Center

    Njemanze, P.C.

    2005-01-01

    The present study evaluated cerebral lateralization during Raven's progressive matrices (RPM) paradigm in female and male subjects. Bilateral simultaneous transcranial Doppler (TCD) ultrasound was used to measure mean blood flow velocities (MBFV) in the right and left middle cerebral arteries (MCAs) in 24 (15 females and 9 males) right-handed…

  8. Ultrasound in the evaluation of enthesitis: status and perspectives

    PubMed Central

    2011-01-01

    Introduction An increasing number of studies have applied ultrasound to the evaluation of entheses in spondyloarthritis patients. However, no clear agreement exists on the definition of enthesitis, on the number and choice of entheses to examine and on ultrasound technique, which may all affect the results of the examination. The objectives of this study were to first determine the level of homogeneity in the ultrasound definitions for the principal lesions of enthesitis in the published literature and second, to evaluate the metric properties of ultrasound for detecting enthesitis according to the OMERACT filter. Methods Search was performed in PUBMED and EMBASE. Both grey-scale and Doppler definitions of enthesitis, including describing features of enthesitis, were collected and metrological qualities of studies were assessed. Results After selection, 48 articles were analyzed. The definition of ultrasound enthesitis and elementary features varied among authors. Grey-scale enthesitis was characterized by increasing thickness (94% of studies), hypoechogenicity (83%), enthesophytes (69%), erosions (67%), calcifications (52%), associated bursitis (46%) and cortical irregularities (29%). Only 46% of studies reported the use of Doppler. High discrepancies were observed on frequency, type of probe and Doppler mode used. Face and content validity were the most frequently evaluated criteria (43%) followed by reliability (29%) and responsiveness (19%). Conclusions Ultrasound has evidence to support face, content validity and reliability for the evaluation of enthesitis, though there is a lack of well-reported methodology in most of the studies. Consensus on elementary lesions and standardization of exam is needed to determine the ultrasound definition of enthesitis in grey-scale and in Doppler for future applications. PMID:22093457

  9. Browsing a wealth of millimeter-wavelength doppler spectra data

    SciTech Connect

    Johnson,K.; Luke,E.; Kollias, P.; Remillard, J.; Widener, K.; Jensen, M.

    2010-03-15

    The ARM Climate Research Facility has collected an extensive archive of vertically pointing millimeter wavelength Doppler radar spectra at both 35 and 95 GHz. These data are a rich potential source of detailed microphysical and dynamical cloud and precipitation information. The recording of spectra, which is ongoing, began at the Southern Great Plains site in September of 2003, at the North Slope of Alaska site in April 2004, and at Tropical Western Pacific sites in 2006. Spectra are also being collected during ARM Mobile Facility deployments. The data’s temporal resolution is as high as two seconds, at height intervals of 45 to 90 m. However, the sheer volume of available data can be somewhat daunting to access and search for specific features of interest. Here we present a user interface for spectra browsing, which allows the user to view time-height images of radar moments, select a time or height of interest, and then “drill down” through images of spectrograms to individual Doppler spectra or time- and height-sequences of spectra. Also available are images summarizing spectral characteristics, such as number of spectral peaks, spectral shape information (skewness and kurtosis), moment uncertainty estimates, and hydrometeor vs. clutter identification as produced by the ARM MicroARSCL (Microphysical Active Remote Sensing of Clouds) value-added product. In addition to the access and visualization tools, we are developing a Doppler spectra simulator capable of generating Doppler spectra from liquid, mixed-phase, and solid cloud constituents and precipitation. The Doppler spectra simulator can be used as an interface between explicit microphysics models and Doppler spectra observations from the ARM radars. The plan is to ultimately make the spectra simulator available from within the spectra browser, allowing a user to associate observed spectra with the microphysical conditions capable of producing them.

  10. Color-Doppler US features of a pyogenic granuloma of the upper dorsum tongue.

    PubMed

    Cantisani, Vito; Del Vecchio, Alessandro; Fioravanti, Eloisa; Romeo, Umberto; D'Ambrosio, Ferdinando

    2016-03-01

    The diagnosis of oral lesions is based on clinical history, clinical examination and imaging exams. Different imaging modalities are available for the diagnosis and follow-up of these lesions such as computed tomography, magnetic resonance imaging, color-Doppler ultrasound, angiography and positron emission tomography. To date, color-Doppler ultrasound is considered the first-line imaging approach since it provides a non-invasive, cost-effective, real-time evaluation of oral anomalies. It provides both morphological and vascular information which are useful to determine the best therapeutic options. Differential diagnosis of a bleeding lobular mass of the tongue is, however, not always easy and includes several vascular and non-vascular lesions. We present herein a case of pyogenic granuloma of the tongue that at Color-Doppler US appeared as hypervascular lesion.

  11. Aerial ultrasonic micro Doppler sonar detection range in outdoor environments.

    PubMed

    Bradley, Marshall; Sabatier, James M

    2012-03-01

    Current research demonstrates that micro Doppler sonar has the capability to uniquely identify the presence of a moving human, making it an attractive component in surveillance systems for border security applications. Primary environmental factors that limit sonar performance are two-way spreading losses, ultrasonic absorption, and backscattered energy from the ground that appears at zero Doppler shift in the sonar signal processor. Spectral leakage from the backscatter component has a significant effect on sonar performance for slow moving targets. Sonar performance is shown to rapidly decay as the sensor is moved closer to the ground due to increasing surface backscatter levels.

  12. Doppler shifted H Ly alpha emission from Jupiter's aurora

    NASA Technical Reports Server (NTRS)

    Clarke, John T.; Trauger, John; Waite, J. Hunter, Jr.

    1989-01-01

    High-spectral-resolution IUE observations of the aurora on Jupiter were obtained in order to search for Doppler shifted H-Ly-alpha emission produced through charge exchange by fast precipitating protons. Although no emission has been observed corresponding to proton energies greater than 200 eV, a large fraction of the H-Ly-alpha emission has appeared Doppler shifted, mainly toward the blue, by about 50 km/s. These results show that the acceleration of ionospheric plasma in an H2 atmosphere can lead to bright Ly-alpha emission, setting constraints on the production of the outer planet airglow emissions.

  13. Ultrasound - Scrotum

    MedlinePlus

    ... especially when the mass is solid). Blood flow images of the testicles are not always reliable in determining the presence or absence of blood supply to a testicle that has twisted. When searching for an absent testicle, ultrasound may not be ...

  14. Doppler detection of arterio-arterial anastomoses in monochorionic twins: feasibility and clinical application.

    PubMed

    Taylor, M J; Denbow, M L; Tanawattanacharoen, S; Gannon, C; Cox, P M; Fisk, N M

    2000-07-01

    The accuracy of in-vivo detection of arterio-arterial anastomoses (AAA) in monochorionic (MC) twins and its predictive value for twin-twin transfusion syndrome (TTTS) was assessed in 105 consecutive MC twins scanned at fortnightly intervals. AAA were sought using spectral and colour energy Doppler and ultrasound findings were compared with placental injection studies. AAA were identified in vivo in 59 (56%) pregnancies and at injection study in 68 (65%). The overall sensitivity and specificity was 85 and 97.3% respectively for the detection of AAA. Detection rates were higher at later gestations, with anterior placentae and with larger diameter AAA. The median insonation time to detect an AAA was 10 min (range 1-30). Where an AAA was identified, 15% of pregnancies (nine of 59) developed TTTS compared to 61% (28 of 46) when no AAA was seen (odds ratio 8.6). We conclude that AAA can be detected in vivo with high sensitivity and specificity without undue prolongation of scanning times and have a role in risk stratification in the antenatal assessment of MC twins.

  15. A thin film phantom for blood flow simulation and Doppler test.

    PubMed

    McAleavey, S; Hah, Z; Parker, K

    2001-05-01

    The thin film phantom is a new type of ultrasound resolution test object. It consists of a thin planar substrate that is acoustically matched to the surrounding media. Precisely located scatterers on the surface of the substrate generate echo signals. The patterning of scatterers on the substrate allows echogenicity to be controlled as a function of position, which enables the production of a test object with highly reproducible and controllable scattering characteristics. We show that by vibrating the substrate in a suitable manner, an echo signal may be generated that simulates bi-directional flow. We demonstrate that a vibration of low amplitude at frequency f0 produces a Doppler spectral signal at f0 and -f0, within the limits of aliasing. Furthermore, by driving the film with a bandlimited noise signal, we illustrate how a velocity distribution may be simulated. A time-varying flow velocity may be simulated by varying the noise bandwidth with time. Finally, using this technique, we demonstrate a system that simulates an arterial flow pattern, including its characteristic velocity distribution in forward and reverse directions simultaneously.

  16. Laser Doppler diagnostics for orthodontia

    NASA Astrophysics Data System (ADS)

    Ryzhkova, Anastasia V.; Lebedeva, Nina G.; Sedykh, Alexey V.; Ulyanov, Sergey S.; Lepilin, Alexander V.; Kharish, Natalia A.

    2004-06-01

    The results of statistical analysis of Doppler spectra of intensity fluctuations of light, scattered from mucous membrane of oral cavity of healthy volunteers and patients, abused by the orthodontic diseases, are presented. Analysis of Doppler spectra, obtained from tooth pulp of patients, is carried out. New approach to monitoring of blood microcirculation in orthodontics is suggested. Influence of own noise of Doppler measuring system on formation of the output signal is studied.

  17. Development of quantitative Doppler indices for uteroplacental and fetal blood flow during the third trimester.

    PubMed

    Joern, H; Funk, A; Goetz, M; Kuehlwein, H; Klein, A; Fendel, H

    1996-01-01

    The aim of our study was to describe the development of uteroplacental and fetal blood flow during the third trimester. Doppler examination was carried out on 393 uncomplicated pregnancies with uncomplicated term delivery. Using a pulsed color Doppler, we calculated the maximum systolic, mean and maximum end-diastolic velocity after correcting the angle of insonation. Patients under tocolysis or other medication influencing blood flow parameters were excluded from this cross-sectional study. Summarizing the results gained by Doppler ultrasound investigation of the uteroplacental and fetal blood vessels, we created quantiles as quantitative Doppler indices for the maximum systolic, mean (TAMX = time averaged maximum velocity) and maximum end-diastolic velocity. The following conclusions could be drawn: (1) resistance to the blood flow in the maternal portion of the placenta does not change during the third trimester; (2) resistance to the blood flow on the fetal side of the placenta decreases up to week 42 of gestation; (3) cerebral vascular resistance decreases constantly up to gestational week 42; and (4) vascular resistance to the blood flow of the kidney decreases only slightly during the third trimester. This study offers clinically important values for quantitative Doppler flow velocimetry for the first time. We hope that our findings improve the usefulness of Doppler ultrasound as a diagnostic tool in obstetrical management.

  18. Laser Doppler velocimetry primer

    NASA Technical Reports Server (NTRS)

    Bachalo, William D.

    1985-01-01

    Advanced research in experimental fluid dynamics required a familiarity with sophisticated measurement techniques. In some cases, the development and application of new techniques is required for difficult measurements. Optical methods and in particular, the laser Doppler velocimeter (LDV) are now recognized as the most reliable means for performing measurements in complex turbulent flows. And such, the experimental fluid dynamicist should be familiar with the principles of operation of the method and the details associated with its application. Thus, the goals of this primer are to efficiently transmit the basic concepts of the LDV method to potential users and to provide references that describe the specific areas in greater detail.

  19. Relationship between cavitation and loss of echogenicity from ultrasound contrast agents.

    PubMed

    Radhakrishnan, Kirthi; Bader, Kenneth B; Haworth, Kevin J; Kopechek, Jonathan A; Raymond, Jason L; Huang, Shao-Ling; McPherson, David D; Holland, Christy K

    2013-09-21

    Ultrasound contrast agents (UCAs) have the potential to nucleate cavitation and promote both beneficial and deleterious bioeffects in vivo. Previous studies have elucidated the pulse-duration-dependent pressure amplitude threshold for rapid loss of echogenicity due to UCA fragmentation. Previous studies have demonstrated that UCA fragmentation was concomitant with inertial cavitation. The purpose of this study was to evaluate the relationship between stable and inertial cavitation thresholds and loss of echogenicity of UCAs as a function of pulse duration. Determining the relationship between cavitation thresholds and loss of echogenicity of UCAs would enable monitoring of cavitation based upon the onscreen echogenicity in clinical applications. Two lipid-shelled UCAs, echogenic liposomes (ELIP) and Definity®, were insonified by a clinical ultrasound scanner in duplex spectral Doppler mode at four pulse durations ('sample volumes') in both a static system and a flow system. Cavitation emissions from the UCAs insonified by Doppler pulses were recorded using a passive cavitation detection system and stable and inertial cavitation thresholds ascertained. Loss of echogenicity from ELIP and Definity® was assessed within regions of interest on B-mode images. A numerical model based on UCA rupture predicted the functional form of the loss of echogenicity from ELIP and Definity®. Stable and inertial cavitation thresholds were found to have a weak dependence on pulse duration. Stable cavitation thresholds were lower than inertial cavitation thresholds. The power of cavitation emissions was an exponential function of the loss of echogenicity over the investigated range of acoustic pressures. Both ELIP and Definity® lost more than 80% echogenicity before the onset of stable or inertial cavitation. Once this level of echogenicity loss occurred, both stable and inertial cavitation were detected in the physiologic flow phantom. These results imply that stable and inertial

  20. Ultrasound findings in cutaneous sarcoidosis

    PubMed Central

    Dybiec, Ewa; Pietrzak, Aldona; Kieszko, Robert; Kanitakis, Jean

    2015-01-01

    The diagnosis of cutaneous sarcoidosis relies mainly on the patient's history, presence of characteristic skin lesions and histological examination that shows a granulomatous, non-necrotizing dermal infiltration. The aim of the study was to assess the ultrasonographic features of cutaneous lesions of sarcoidosis before and after treatment. A 38-year-old woman with systemic sarcoidosis and specific cutaneous lesions was treated with systemic steroids followed by hydroxychloroquine. Ultrasonographic examination of the cutaneous sarcoidosis lesions was performed with a Philips iU 22 and Siemens Acuson S 2000 device, with the use of linear 15 MHz and 17 MHz transducers. Histological examination of skin lesions showed characteristic, naked, non-necrotizing granulomas in the upper dermis. Ultrasound examination revealed well-demarcated, hypoechogenic changes. Power-Doppler scan revealed increased vascularity within the lesions and the surrounding tissue. Clinical improvement of the skin lesions was confirmed by ultrasound examination, which showed a decrease in their size and normalization of dermal echogenicity and vascularity. Ultrasound examination can show cutaneous sarcoidosis lesions and their regression after appropriate treatment. PMID:25821428

  1. Ultrasound Techniques for Space Applications

    NASA Technical Reports Server (NTRS)

    Rooney, James A.

    1985-01-01

    Ultrasound has proven to be a safe non-invasive technique for imaging organs and measuring cardiovascular function. It has unique advantages for application to problems with man in space including evaluation of cardiovascular function both in serial studies and during critical operations. In addition, specialized instrumentation may be capable of detecting the onset of decompression sickness during EVA activities. A spatial location and three-dimensional reconstruction system is being developed to improve the accuracy and reproducibility for serial comparative ultrasound studies of cardiovascular function. The three-dimensional method permits the acquisition of ultrasonic images from many views that can be recombined into a single reconstruction of the heart or vasculature. In addition to conventional imaging and monitoring systems, it is sometimes necessary or desirable to develop instrumentation for special purposes. One example of this type of development is the design of a pulsed-Doppler system to monitor cerebral blood flow during critical operations such as re-entry. A second example is the design of a swept-frequency ultrasound system for the detection of bubbles in the circulatory system and/or soft tissues as an early indication of the onset of decompression sickness during EVA activities. This system exploits the resonant properties of bubbles and can detect both fundamental and second harmonic emissions from the insonified region.

  2. Rotational Doppler Effect: A Probe for Molecular Orbitals Anisotropy.

    PubMed

    Miao, Quan; Travnikova, Oksana; Gel'mukhanov, Faris; Kimberg, Victor; Sun, Yu-Ping; Thomas, T Darrah; Nicolas, Christophe; Patanen, Minna; Miron, Catalin

    2015-05-07

    The vibrationally resolved X-ray photoelectron spectra of X2Σg+(3σg−1) and B2Σu+(2σu−1) states of N2+ were recorded for different photon energies and orientations of the polarization vector. Clear dependencies of the spectral line widths on the X-ray polarization as well as on the symmetry of the final electronic states are observed. Contrary to the translational Doppler, the rotational Doppler broadening is sensitive to the photoelectron emission anisotropy. On the basis of theoretical modeling, we suggest that the different rotational Doppler broadenings observed for gerade and ungerade final states result from a Young's double-slit interference phenomenon.

  3. Modeling and processing of laser Doppler reactive hyperaemia signals

    NASA Astrophysics Data System (ADS)

    Humeau, Anne; Saumet, Jean-Louis; L'Huiller, Jean-Pierre

    2003-07-01

    Laser Doppler flowmetry is a non-invasive method used in the medical domain to monitor the microvascular blood cell perfusion through tissue. Most commercial laser Doppler flowmeters use an algorithm calculating the first moment of the power spectral density to give the perfusion value. Many clinical applications measure the perfusion after a vascular provocation such as a vascular occlusion. The response obtained is then called reactive hyperaemia. Target pathologies include diabetes, hypertension and peripheral arterial occlusive diseases. In order to have a deeper knowledge on reactive hyperaemia acquired by the laser Doppler technique, the present work first proposes two models (one analytical and one numerical) of the observed phenomenon. Then, a study on the multiple scattering between photons and red blood cells occurring during reactive hyperaemia is carried out. Finally, a signal processing that improves the diagnosis of peripheral arterial occlusive diseases is presented.

  4. Robust estimation of fetal heart rate from US Doppler signals

    NASA Astrophysics Data System (ADS)

    Voicu, Iulian; Girault, Jean-Marc; Roussel, Catherine; Decock, Aliette; Kouame, Denis

    2010-01-01

    Introduction: In utero, Monitoring of fetal wellbeing or suffering is today an open challenge, due to the high number of clinical parameters to be considered. An automatic monitoring of fetal activity, dedicated for quantifying fetal wellbeing, becomes necessary. For this purpose and in a view to supply an alternative for the Manning test, we used an ultrasound multitransducer multigate Doppler system. One important issue (and first step in our investigation) is the accurate estimation of fetal heart rate (FHR). An estimation of the FHR is obtained by evaluating the autocorrelation function of the Doppler signals for ills and healthiness foetus. However, this estimator is not enough robust since about 20% of FHR are not detected in comparison to a reference system. These non detections are principally due to the fact that the Doppler signal generated by the fetal moving is strongly disturbed by the presence of others several Doppler sources (mother' s moving, pseudo breathing, etc.). By modifying the existing method (autocorrelation method) and by proposing new time and frequency estimators used in the audio' s domain, we reduce to 5% the probability of non-detection of the fetal heart rate. These results are really encouraging and they enable us to plan the use of automatic classification techniques in order to discriminate between healthy and in suffering foetus.

  5. Doppler ultrasound exam of an arm or leg

    MedlinePlus

    ... later. The test is done to help diagnose: Arteriosclerosis of the arms or legs Blood clot (deep ... the wrong direction in veins) Arterial occlusion from atherosclerosis This test may also be done to help ...

  6. [A versatile phantom for hemodynamic measurements with ultrasound Doppler equipment].

    PubMed

    von Boetticher, H; Delebinski, R; Risch, U; Luska, G

    1994-10-01

    The test object described comprises a blood simulating liquid pumped through tubes embedded in tissue-mimicking material. The main components of the system can be realised in different ways. They are largely exchangeable with each other. Water, reticulated foam or silicone rubber is used as bulk background material, blood vessels are simulated using latex or silicone tubes or heat-shrink sleeving; in the artificial blood, sephadex particles or silicone emulsion were used as scatterers. The suspension of scattering particles is driven by a roller pump or a membrane dosage pump. The features of the components are described and the applications of the different phantoms discussed.

  7. General Ultrasound Imaging

    MedlinePlus

    ... waves. Ultrasound imaging, also called ultrasound scanning or sonography , involves the use of a small transducer (probe) and ultrasound gel placed directly on the skin. High-frequency sound waves are transmitted from the ...

  8. Venous Ultrasound (Extremities)

    MedlinePlus

    ... waves. Ultrasound imaging, also called ultrasound scanning or sonography , involves the use of a small transducer (probe) and ultrasound gel placed directly on the skin. High-frequency sound waves are transmitted from the ...

  9. Carotid Ultrasound Imaging

    MedlinePlus

    ... waves. Ultrasound imaging, also called ultrasound scanning or sonography , involves the use of a small transducer (probe) and ultrasound gel placed directly on the skin. High-frequency sound waves are transmitted from the ...

  10. A novel approach for Doppler blood flow measurement.

    PubMed

    McNamara, D M; Goli, A; Ziarani, A K

    2008-01-01

    A new approach to frequency estimation for the velocity estimation in Doppler ultrasound blood flow analysis is presented. The basis of the approach is an adaptive sinusoid-tracking algorithm which is effective in extracting nonstationary signals from within noise and estimating their time-varying parameters, such as the frequency, over time. The preliminary studies conducted using simulated signals show the potential of this approach in estimating Doppler frequency shifts under noisy conditions. A qualitative comparison with the short-time Fourier transform (STFT) is presented to show the advantages of the proposed technique over the STFT. The proposed approach offers advantages over conventional time-frequency analysis techniques in terms of high time-frequency resolution and high noise immunity.

  11. Are Prenatal Ultrasound Scans Associated with the Autism Phenotype? Follow-Up of a Randomised Controlled Trial

    ERIC Educational Resources Information Center

    Stoch, Yonit K.; Williams, Cori J.; Granich, Joanna; Hunt, Anna M.; Landau, Lou I.; Newnham, John P.; Whitehouse, Andrew J. O.

    2012-01-01

    An existing randomised controlled trial was used to investigate whether multiple ultrasound scans may be associated with the autism phenotype. From 2,834 single pregnancies, 1,415 were selected at random to receive ultrasound imaging and continuous wave Doppler flow studies at five points throughout pregnancy (Intensive) and 1,419 to receive a…

  12. Doppler Beats or Interference Fringes?

    ERIC Educational Resources Information Center

    Kelly, Paul S.

    1979-01-01

    Discusses the following: another version of Doppler beats; alternate proof of spin-1 sin-1/2 problems; some mechanisms related to Dirac's strings; Doppler redshift in oblique approach of source and observer; undergraduate experiment on noise thermometry; use of the time evolution operator; resolution of an entropy maximization controversy;…

  13. Eye and orbit ultrasound

    MedlinePlus

    Echography - eye orbit; Ultrasound - eye orbit; Ocular ultrasonography; Orbital ultrasonography ... ophthalmology department of a hospital or clinic. Your eye is numbed with medicine (anesthetic drops). The ultrasound ...

  14. Transcranial Doppler: Techniques and advanced applications: Part 2

    PubMed Central

    Sharma, Arvind K.; Bathala, Lokesh; Batra, Amit; Mehndiratta, Man Mohan; Sharma, Vijay K.

    2016-01-01

    Transcranial Doppler (TCD) is the only diagnostic tool that can provide continuous information about cerebral hemodynamics in real time and over extended periods. In the previous paper (Part 1), we have already presented the basic ultrasound physics pertaining to TCD, insonation methods, and various flow patterns. This article describes various advanced applications of TCD such as detection of right-to-left shunt, emboli monitoring, vasomotor reactivity (VMR), monitoring of vasospasm in subarachnoid hemorrhage (SAH), monitoring of intracranial pressure, its role in stoke prevention in sickle cell disease, and as a supplementary test for confirmation of brain death. PMID:27011639

  15. DOPPLER SIGNATURES OF THE ATMOSPHERIC CIRCULATION ON HOT JUPITERS

    SciTech Connect

    Showman, Adam P.; Lewis, Nikole K.; Fortney, Jonathan J.; Shabram, Megan

    2013-01-01

    The meteorology of hot Jupiters has been characterized primarily with thermal measurements, but recent observations suggest the possibility of directly detecting the winds by observing the Doppler shift of spectral lines seen during transit. Motivated by these observations, we show how Doppler measurements can place powerful constraints on the meteorology. We show that the atmospheric circulation-and Doppler signature-of hot Jupiters splits into two regimes. Under weak stellar insolation, the day-night thermal forcing generates fast zonal jet streams from the interaction of atmospheric waves with the mean flow. In this regime, air along the terminator (as seen during transit) flows toward Earth in some regions and away from Earth in others, leading to a Doppler signature exhibiting superposed blueshifted and redshifted components. Under intense stellar insolation, however, the strong thermal forcing damps these planetary-scale waves, inhibiting their ability to generate jets. Strong frictional drag likewise damps these waves and inhibits jet formation. As a result, this second regime exhibits a circulation dominated by high-altitude, day-to-night airflow, leading to a predominantly blueshifted Doppler signature during transit. We present state-of-the-art circulation models including non-gray radiative transfer to quantify this regime shift and the resulting Doppler signatures; these models suggest that cool planets like GJ 436b lie in the first regime, HD 189733b is transitional, while planets hotter than HD 209458b lie in the second regime. Moreover, we show how the amplitude of the Doppler shifts constrains the strength of frictional drag in the upper atmospheres of hot Jupiters. If due to winds, the {approx}2 km s{sup -1} blueshift inferred on HD 209458b may require drag time constants as short as 10{sup 4}-10{sup 6} s, possibly the result of Lorentz-force braking on this planet's hot dayside.

  16. Long duration meteor echoes characterized by Doppler spectrum bifurcation

    NASA Astrophysics Data System (ADS)

    Bourdillon, A.; Haldoupis, C.; Hanuise, C.; Le Roux, Y.; Menard, J.

    2005-03-01

    We report on a new category of long lasting meteor echoes observed occasionally with HF and VHF radars. These meteoric returns, which have lifetimes from many seconds to a few minutes, are characterized by a distinct Doppler spectral signature showing a pronounced Doppler bifurcation which includes narrow bands of discrete Doppler velocities, often of opposite polarity. The large signal to noise ratios and the narrowness of the spectra imply that coherent or Bragg scattering is not of relevance here, therefore these echoes do not associate with the long living meteor-induced backscatter (MIB) from the lower E region. A reasonable interpretation needs to explain both the Doppler spectrum bifurcation and the long echo duration. As such, we propose the idea of a structured vertical wind shear in the lower E region which traps different fragments of a meteor trail plasma in the same way that sporadic E layers form. These trail parts inside the shear-related wind profile may act as relatively long-lasting meteoric reflectors moving with different Doppler velocities, also of opposite polarity.

  17. Three-dimensional ultrasound evaluation of the placenta.

    PubMed

    Hata, T; Tanaka, H; Noguchi, J; Hata, K

    2011-02-01

    Conventional two-dimensional (2D) ultrasound has been widely used for the evaluation of the placenta during pregnancy. This 2D ultrasound evaluation includes the morphology, anatomy, location, implantation, anomaly, size, and color/power and pulsed Doppler sonographic assessment of the placenta. The introduction of three-dimensional (3D) ultrasound would facilitate the novel assessment of the placenta, such as surface-rendered imaging and volume measurement. With the recent advances in 3D power Doppler (3DPD) ultrasound as well as quantitative 3DPD histogram analysis, quantitative and qualitative assessments of the vascularization and blood flow of the placenta have become feasible. These novel techniques may assist in the evaluation of the feto-placental function, and offer potential advantages relative to conventional 2D sonographic assessments. 3D ultrasound may be an important modality in future placental research, in the evaluation of feto-placental insufficiency in clinical practice, and in the prediction of fetal growth restriction and pre-eclampsia, although some limitations regarding the assessment of the placenta employing 3D ultrasound still remain unresolved.

  18. Optic Nerve Sheath Diameter Ultrasound and the Diagnosis of Increased Intracranial Pressure.

    PubMed

    Hylkema, Christopher

    2016-03-01

    Ultrasound has been used for almost 30 years in a wide variety of clinical applications and environments. From the austerity of battlefields to the labor and delivery ward, ultrasound has the ability to give clinicians real-time, noninvasive diagnostic imaging. Ultrasound by emergency physicians (and all nonradiologists) has become more prevalent and has been used for examinations such as the transcranial Doppler to evaluate for stroke, cardiac function, FAST and EFAST examinations for trauma, and now increased intracranial pressure (ICP) via Optic Nerve Sheath Diameter Ultrasound (ONSD). The ONSD is a valid and reliable indicator of ICP.

  19. [Modern ultrasound methods of examination in clinical ophthalmology. Background problems and future prospects].

    PubMed

    Kharlap, S I

    2003-01-01

    Historic aspects of ultrasound diagnostics in ophthalmology are described. The technological development of ultrasound diagnostic systems and the clinical application of different ultrasound modes in examining the eye and its choroids are traced back. The efficiency of Doppler mapping in the mode of three-dimension reconstruction at examining the orbital vascular system is evaluated. An experience obtained at the Research Institute for Eye Disease of the Russian Academy of Medical Sciences and outlooks for the diagnostic usage of computer ultrasound in clinical ophthalmology and angiologia are presented.

  20. Incidentally detection of non-palpable testicular nodules at scrotal ultrasound: what is new?

    PubMed

    Valentino, Massimo; Bertolotto, Michele; Martino, Pasquale; Barozzi, Libero; Pavlica, Pietro

    2014-12-30

    The increased use of ultrasound in patients with urological and andrological symptoms has given an higher detection of intra-testicular nodules. Most of these lesions are hypoechoic and their interpretation is often equivocal. Recently, new ultrasound techniques have been developed alongside of B-mode and color-Doppler ultrasound. Although not completely standardized, contrast-enhanced ultrasound (CEUS) and tissue elastography (TE), added to traditional ultrasonography, can provide useful information about the correct interpretation of incidentally detected non-palpable testicular nodules. The purpose of this review article is to illustrate these new techniques in the patient management.

  1. Validation of volumetric flow measurements by means of a Doppler-tipped coronary angioplasty guide wire.

    PubMed

    Labovitz, A J; Anthonis, D M; Cravens, T L; Kern, M J

    1993-12-01

    We used an in vitro model to validate volumetric flow measurements obtained with an 0.018-inch angioplasty guidewire with a 12 MHz transducer mounted on its tip. By using a modified two-head roller pump device, flow was adjusted incrementally from a minimum of 90 ml/min to a maximum of 550 ml/min. Flow was measured with the Doppler guide wire in tubing ranging from 1.9 mm to 6.0 mm internal diameter, as the product of the spectral Doppler velocity integral and the cross-sectional area of the tubing, over a 1-minute period. It was an excellent correlation between the Doppler calculated flow rates and actual flow, regardless of tubing diameter (r = 0.99). These results suggest that the Doppler spectral output of this device might be accurately applied to estimates of volumetric flow in human coronary arteries.

  2. Real-time clinically oriented array-based in vivo combined photoacoustic and power Doppler imaging

    NASA Astrophysics Data System (ADS)

    Harrison, Tyler; Jeffery, Dean; Wiebe, Edward; Zemp, Roger J.

    2014-03-01

    Photoacoustic imaging has great potential for identifying vascular regions for clinical imaging. In addition to assessing angiogenesis in cancers, there are many other disease processes that result in increased vascularity that present novel targets for photoacoustic imaging. Doppler imaging can provide good localization of large vessels, but poor imaging of small or low flow speed vessels and is susceptible to motion artifacts. Photoacoustic imaging can provide visualization of small vessels, but due to the filtering effects of ultrasound transducers, only shows the edges of large vessels. Thus, we have combined photoacoustic imaging with ultrasound power Doppler to provide contrast agent- free vascular imaging. We use a research-oriented ultrasound array system to provide interlaced ultrasound, Doppler, and photoacoustic imaging. This system features realtime display of all three modalities with adjustable persistence, rejection, and compression. For ease of use in a clinical setting, display of each mode can be disabled. We verify the ability of this system to identify vessels with varying flow speeds using receiver operating characteristic curves, and find that as flow speed falls, photoacoustic imaging becomes a much better method for identifying blood vessels. We also present several in vivo images of the thyroid and several synovial joints to assess the practicality of this imaging for clinical applications.

  3. Spread-Spectrum Carrier Estimation With Unknown Doppler Shift

    NASA Technical Reports Server (NTRS)

    DeLeon, Phillip L.; Scaife, Bradley J.

    1998-01-01

    We present a method for the frequency estimation of a BPSK modulated, spread-spectrum carrier with unknown Doppler shift. The approach relies on a classic periodogram in conjunction with a spectral matched filter. Simulation results indicate accurate carrier estimation with processing gains near 40. A DSP-based prototype has been implemented for real-time carrier estimation for use in New Mexico State University's proposal for NASA's Demand Assignment Multiple Access service.

  4. GEOS-3 Doppler difference tracking

    NASA Technical Reports Server (NTRS)

    Rosenbaum, B.

    1977-01-01

    The Doppler difference method as applied to track the GEOS 3 spacecraft is discussed. In this method a pair of 2 GHz ground tracking stations simultaneously track a spacecraft beacon to generate an observable signal in which bias and instability of the carrier frequency cancel. The baselines are formed by the tracking sites at Bermuda, Rosman, and Merritt Island. Measurements were made to evaluate the effectiveness of the Doppler differencing procedure in tracking a beacon target with the high dynamic rate of the GEOS 3 orbit. Results indicate the precision of the differenced data to be at a level comparable to the conventional precise two way Doppler tracking.

  5. Digital Doppler measurement with spacecraft

    NASA Technical Reports Server (NTRS)

    Kinman, Peter W.; Hinedi, Sami M.; Labelle, Remi C.; Bevan, Roland P.; Del Castillo, Hector M.; Chong, Dwayne C.

    1991-01-01

    Digital and analog phase-locked loop (PLL) receivers were operated in parallel, each tracking the residual carrier from a spacecraft. The PLL tracked the downlink carrier and measured its instantaneous phase. This information, combined with a knowledge of the uplink carrier and the transponder ratio, permitted the computation of a Doppler observable. In this way, two separate Doppler measurements were obtained for one observation window. The two receivers agreed on the magnitude of the Doppler effect to within 1 mHz. There was less jitter on the data from the digital receiver. This was due to its smaller noise bandwidth. The demonstration and its results are described.

  6. A novel application of musculoskeletal ultrasound imaging.

    PubMed

    Eranki, Avinash; Cortes, Nelson; Ferenček, Zrinka Gregurić; Sikdar, Siddhartha

    2013-09-17

    Ultrasound is an attractive modality for imaging muscle and tendon motion during dynamic tasks and can provide a complementary methodological approach for biomechanical studies in a clinical or laboratory setting. Towards this goal, methods for quantification of muscle kinematics from ultrasound imagery are being developed based on image processing. The temporal resolution of these methods is typically not sufficient for highly dynamic tasks, such as drop-landing. We propose a new approach that utilizes a Doppler method for quantifying muscle kinematics. We have developed a novel vector tissue Doppler imaging (vTDI) technique that can be used to measure musculoskeletal contraction velocity, strain and strain rate with sub-millisecond temporal resolution during dynamic activities using ultrasound. The goal of this preliminary study was to investigate the repeatability and potential applicability of the vTDI technique in measuring musculoskeletal velocities during a drop-landing task, in healthy subjects. The vTDI measurements can be performed concurrently with other biomechanical techniques, such as 3D motion capture for joint kinematics and kinetics, electromyography for timing of muscle activation and force plates for ground reaction force. Integration of these complementary techniques could lead to a better understanding of dynamic muscle function and dysfunction underlying the pathogenesis and pathophysiology of musculoskeletal disorders.

  7. A Novel Application of Musculoskeletal Ultrasound Imaging

    PubMed Central

    Eranki, Avinash; Cortes, Nelson; Ferenček, Zrinka Gregurić; Sikdar, Siddhartha

    2013-01-01

    Ultrasound is an attractive modality for imaging muscle and tendon motion during dynamic tasks and can provide a complementary methodological approach for biomechanical studies in a clinical or laboratory setting. Towards this goal, methods for quantification of muscle kinematics from ultrasound imagery are being developed based on image processing. The temporal resolution of these methods is typically not sufficient for highly dynamic tasks, such as drop-landing. We propose a new approach that utilizes a Doppler method for quantifying muscle kinematics. We have developed a novel vector tissue Doppler imaging (vTDI) technique that can be used to measure musculoskeletal contraction velocity, strain and strain rate with sub-millisecond temporal resolution during dynamic activities using ultrasound. The goal of this preliminary study was to investigate the repeatability and potential applicability of the vTDI technique in measuring musculoskeletal velocities during a drop-landing task, in healthy subjects. The vTDI measurements can be performed concurrently with other biomechanical techniques, such as 3D motion capture for joint kinematics and kinetics, electromyography for timing of muscle activation and force plates for ground reaction force. Integration of these complementary techniques could lead to a better understanding of dynamic muscle function and dysfunction underlying the pathogenesis and pathophysiology of musculoskeletal disorders. PMID:24084063

  8. Implementation of a versatile research data acquisition system using a commercially available medical ultrasound scanner.

    PubMed

    Hemmsen, Martin Christian; Nikolov, Svetoslav Ivanov; Pedersen, Mads Møller; Pihl, Michael Johannes; Enevoldsen, Marie Sand; Hansen, Jens Munk; Jensen, Jørgen Arendt

    2012-07-01

    This paper describes the design and implementation of a versatile, open-architecture research data acquisition system using a commercially available medical ultrasound scanner. The open architecture will allow researchers and clinicians to rapidly develop applications and move them relatively easy to the clinic. The system consists of a standard PC equipped with a camera link and an ultrasound scanner equipped with a research interface. The ultrasound scanner is an easy-to-use imaging device that is capable of generating high-quality images. In addition to supporting the acquisition of multiple data types, such as B-mode, M-mode, pulsed Doppler, and color flow imaging, the machine provides users with full control over imaging parameters such as transmit level, excitation waveform, beam angle, and focal depth. Beamformed RF data can be acquired from regions of interest throughout the image plane and stored to a file with a simple button press. For clinical trials and investigational purposes, when an identical image plane is desired for both an experimental and a reference data set, interleaved data can be captured. This form of data acquisition allows switching between multiple setups while maintaining identical transducer, scanner, region of interest, and recording time. Data acquisition is controlled through a graphical user interface running on the PC. This program implements an interface for third-party software to interact with the application. A software development toolkit is developed to give researchers and clinicians the ability to utilize third-party software for data analysis and flexible manipulation of control parameters. Because of the advantages of speed of acquisition and clinical benefit, research projects have successfully used the system to test and implement their customized solutions for different applications. Three examples of system use are presented in this paper: evaluation of synthetic aperture sequential beamformation, transverse

  9. Applications of Doppler-Free Saturation Spectroscopy for Edge Physics Studies

    SciTech Connect

    Martin, Elijah H; Caughman, John B; Isler, Ralph C; Bell, Gary L

    2016-01-01

    Doppler-free saturation spectroscopy provides a very powerful method to obtained detailed information about the electronic structure of the atom through measurement of the spectral line profile. This is achieved through a significant decrease in the Doppler broadening and essentially an elimination of the instrument broadening inherent to passive spectroscopic techniques. In this paper we will present the technique and associated physics of Doppler-free saturation spectroscopy in addition to how one selects the appropriate transition. Simulations of H spectra will be presented to illustrate the increased sensitivity to both electric field and electron density measurements.

  10. Reducing Spaceborne-Doppler-Radar Rainfall-Velocity Error

    NASA Technical Reports Server (NTRS)

    Tanelli, Simone; Im, Eastwood; Durden, Stephen L.

    2008-01-01

    A combined frequency-time (CFT) spectral moment estimation technique has been devised for calculating rainfall velocity from measurement data acquired by a nadir-looking spaceborne Doppler weather radar system. Prior spectral moment estimation techniques used for this purpose are based partly on the assumption that the radar resolution volume is uniformly filled with rainfall. The assumption is unrealistic in general but introduces negligible error in application to airborne radar systems. However, for spaceborne systems, the combination of this assumption and inhomogeneities in rainfall [denoted non-uniform beam filling (NUBF)] can result in velocity measurement errors of several meters per second. The present CFT spectral moment estimation technique includes coherent processing of a series of Doppler spectra generated in a standard manner from data over measurement volumes that are partially overlapping in the along-track direction. Performance simulation of this technique using high-resolution data from an airborne rain-mapping radar shows that a spaceborne Ku-band Doppler radar operating at signal-to-noise ratios greater than 10 dB can achieve root-mean-square accuracy between 0.5 and 0.6 m/s in vertical-velocity estimates.

  11. Doppler radar detection of vortex hazard indicators

    NASA Technical Reports Server (NTRS)

    Nespor, Jerald D.; Hudson, B.; Stegall, R. L.; Freedman, Jerome E.

    1994-01-01

    Wake vortex experiments were conducted at White Sands Missile Range, NM using the AN/MPS-39 Multiple Object Tracking Radar (MOTR). The purpose of these experiments was twofold. The first objective was to verify that radar returns from wake vortex are observed for some time after the passage of an aircraft. The second objective was to verify that other vortex hazard indicators such as ambient wind speed and direction could also be detected. The present study addresses the Doppler characteristics of wake vortex and clear air returns based upon measurements employing MOTR, a very sensitive C-Band phased array radar. In this regard, the experiment was conducted so that the spectral characteristics could be determined on a dwell to-dwell basis. Results are presented from measurements of the backscattered power (equivalent structure constant), radial velocity and spectral width when the aircraft flies transverse and axial to the radar beam. The statistics of the backscattered power and spectral width for each case are given. In addition, the scan strategy, experimental test procedure and radar parameters are presented.

  12. Ultrasound and Therapy

    NASA Astrophysics Data System (ADS)

    Lafon, Cyril

    This paper begins with an overview and a description of the interactions between ultrasound and biological tissues encountered during treatment protocols. In a second part of this seminar, two clinical applications of therapeutic ultrasound will be described in details: -Kidney stone destruction by ultrasound (lithotripsy) and High Intensity Focused Ultrasound for treating prostate cancer (HIFU).

  13. [Ultrasound in emergency medicine].

    PubMed

    Lapostolle, F; Deltour, S; Petrovic, T

    2015-12-01

    Ultrasound has revolutionized the practice of emergency medicine, particularly in prehospital setting. About a patient with dyspnea, we present the role of ultrasound in the diagnosis and emergency treatment. Echocardiography, but also hemodynamic ultrasound (vena cava) and lung exam are valuable tools. Achieving lung ultrasound and diagnostic value of B lines B are detailed.

  14. Evaluation of meteorological airborne Doppler radar

    NASA Technical Reports Server (NTRS)

    Hildebrand, P. H.; Mueller, C. K.

    1984-01-01

    This paper will discuss the capabilities of airborne Doppler radar for atmospheric sciences research. The evaluation is based on airborne and ground based Doppler radar observations of convective storms. The capability of airborne Doppler radar to measure horizontal and vertical air motions is evaluated. Airborne Doppler radar is shown to be a viable tool for atmospheric sciences research.

  15. Ultrasound Thermal Field Imaging of Opaque Fluids

    NASA Technical Reports Server (NTRS)

    Andereck, C. David

    1999-01-01

    We have initiated an experimental program to develop an ultrasound system for non-intrusively imaging the thermal field in opaque fluids under an externally imposed temperature gradient. Many industrial processes involve opaque fluids, such as molten metals, semiconductors, and polymers, often in situations in which thermal gradients are important. For example, one may wish to understand semiconductor crystal growth dynamics in a Bridgman apparatus. Destructive testing of the crystal after the process is completed gives only indirect information about the fluid dynamics of the formation process. Knowledge of the coupled thermal and velocity fields during the growth process is then essential. Most techniques for non-intrusive velocity and temperature measurement in fluids are optical in nature, and hence the fluids studied must be transparent. In some cases (for example, LDV (laser Doppler velocimetry) and PIV (particle imaging velocimetry)) the velocities of small neutrally buoyant seed particles suspended in the fluid, are measured. Without particle seeding one can use the variation of the index of refraction of the fluid with temperature to visualize, through interferometric, Schlieren or shadowgraph techniques, the thermal field. The thermal field in turn gives a picture of the pattern existing in the fluid. If the object of study is opaque, non-optical techniques must be used. In this project we focus on the use of ultrasound, which propagates easily through opaque liquids and solids. To date ultrasound measurements have almost exclusively relied on the detection of sound scattered from density discontinuities inside the opaque material of interest. In most cases it has been used to visualize structural properties, but more recently the ultrasound Doppler velocimeter has become available. As in the optical case, it relies on seed particles that scatter Doppler shifted sound back to the detector. Doppler ultrasound techniques are, however, not useful for

  16. The generalized Doppler effect for surface waves

    NASA Astrophysics Data System (ADS)

    Michel, G.

    2016-11-01

    We investigate energy exchanges through scales occurring when a surface wave reflects on a harmonically oscillating wall. We first experimentally evidence the creation of Doppler-shifted waves and measure their height as a function of the oscillation amplitude. Then, we theoretically compute the amplitudes of these new waves in the gravity regime. Both results show that even without bulk non-linearities, oscillating paddles in a fluid container lead to a complex wave energy spectrum competing with the one predicted by wave turbulence. To exemplify this point, we characterize a simple one-dimensional model consisting of a linear wave equation in an oscillating cavity with distinct injection and dissipation mechanisms. It displays features usually associated with non-linearities, as self-similarity in a spectral domain (the so-called inertial range), appearance of energy at larger and/or lower scales than the forcing one and creation of shock waves.

  17. Dual-Doppler Feasibility Study

    NASA Technical Reports Server (NTRS)

    Huddleston, Lisa L.

    2012-01-01

    When two or more Doppler weather radar systems are monitoring the same region, the Doppler velocities can be combined to form a three-dimensional (3-D) wind vector field thus providing for a more intuitive analysis of the wind field. A real-time display of the 3-D winds can assist forecasters in predicting the onset of convection and severe weather. The data can also be used to initialize local numerical weather prediction models. Two operational Doppler Radar systems are in the vicinity of Kennedy Space Center (KSC) and Cape Canaveral Air Force Station (CCAFS); these systems are operated by the 45th Space Wing (45 SW) and the National Weather Service Melbourne, Fla. (NWS MLB). Dual-Doppler applications were considered by the 45 SW in choosing the site for the new radar. Accordingly, the 45th Weather Squadron (45 WS), NWS MLB and the National Aeronautics and Space Administration tasked the Applied Meteorology Unit (AMU) to investigate the feasibility of establishing dual-Doppler capability using the two existing systems. This study investigated technical, hardware, and software requirements necessary to enable the establishment of a dual-Doppler capability. Review of the available literature pertaining to the dual-Doppler technique and consultation with experts revealed that the physical locations and resulting beam crossing angles of the 45 SW and NWS MLB radars make them ideally suited for a dual-Doppler capability. The dual-Doppler equations were derived to facilitate complete understanding of dual-Doppler synthesis; to determine the technical information requirements; and to determine the components of wind velocity from the equation of continuity and radial velocity data collected by the two Doppler radars. Analysis confirmed the suitability of the existing systems to provide the desired capability. In addition, it is possible that both 45 SW radar data and Terminal Doppler Weather Radar data from Orlando International Airport could be used to alleviate any

  18. Doppler characteristics of sea clutter.

    SciTech Connect

    Raynal, Ann Marie; Doerry, Armin Walter

    2010-06-01

    Doppler radars can distinguish targets from clutter if the target's velocity along the radar line of sight is beyond that of the clutter. Some targets of interest may have a Doppler shift similar to that of clutter. The nature of sea clutter is different in the clutter and exo-clutter regions. This behavior requires special consideration regarding where a radar can expect to find sea-clutter returns in Doppler space and what detection algorithms are most appropriate to help mitigate false alarms and increase probability of detection of a target. This paper studies the existing state-of-the-art in the understanding of Doppler characteristics of sea clutter and scattering from the ocean to better understand the design and performance choices of a radar in differentiating targets from clutter under prevailing sea conditions.

  19. Doppler tracking of planetary spacecraft

    NASA Technical Reports Server (NTRS)

    Kinman, Peter W.

    1992-01-01

    This article concerns the measurement of Doppler shift on microwave links that connect planetary spacecraft with the Deep Space Network. Such measurements are made by tracking the Doppler effect with phase-locked loop receivers. A description of equipment and techniques as well as a summary of the appropriate mathematical models are given. The two-way Doppler shift is measured by transmitting a highly-stable microwave (uplink) carrier from a ground station, having the spacecraft coherently transpond this carrier, and using a phase-locked loop receiver at the ground station to track the returned (downlink) carrier. The largest sources of measurement error are usually plasma noise and thermal noise. The plasma noise, which may originate in the ionosphere or the solar corona, is discussed; and a technique to partially calibrate its effect, involving the use of two simultaneous downlink carriers that are coherently related, is described. Range measurements employing Doppler rate-aiding are also described.

  20. Spatially-Resolved Temperature Diagnostic for Supersonic Flow Using Cross-Beam Doppler-Limited Laser Saturation Spectroscopy

    DTIC Science & Technology

    2006-03-01

    58 Cross-Beam Inter-Modulated Fluorescence Spectroscopy .................................... 61 B. Spectral Profiles for I2 Ro...intensity of the i th I2 hyperfine spectral line ( )νg spectral profile (in general) ( )νg lineshape normalized to unity at line center, i.e...L C I L CS ν νννα ναν (132) for a single Doppler-broadened transition. B. Spectral Profiles for I2 Ro-vibrational Lines To represent

  1. Mathematical Models for Doppler Measurements

    NASA Technical Reports Server (NTRS)

    Lear, William M.

    1987-01-01

    Error analysis increases precision of navigation. Report presents improved mathematical models of analysis of Doppler measurements and measurement errors of spacecraft navigation. To take advantage of potential navigational accuracy of Doppler measurements, precise equations relate measured cycle count to position and velocity. Drifts and random variations in transmitter and receiver oscillator frequencies taken into account. Mathematical models also adapted to aircraft navigation, radar, sonar, lidar, and interferometry.

  2. Novel instantaneous laser Doppler velocimeter.

    PubMed

    Avidor, J M

    1974-02-01

    A laser Doppler velocimeter capable of directly measuring instantaneous velocities is described. The new LDV uses a novel detection technique based on the utilization of a static slightly defocused spherical Fabry-Perot interferometer used in conjunction with a special mask for the detection of instantaneous Doppler frequency shifts. The essential characteristics of this LDV are discussed, and such a system recently developed is described. Results of turbulent flow measurements show good agreement with data obtained using hot wire anemometry.

  3. WE-B-210-02: The Advent of Ultrafast Imaging in Biomedical Ultrasound

    SciTech Connect

    Tanter, M.

    2015-06-15

    In the last fifteen years, the introduction of plane or diverging wave transmissions rather than line by line scanning focused beams has broken the conventional barriers of ultrasound imaging. By using such large field of view transmissions, the frame rate reaches the theoretical limit of physics dictated by the ultrasound speed and an ultrasonic map can be provided typically in tens of micro-seconds (several thousands of frames per second). Interestingly, this leap in frame rate is not only a technological breakthrough but it permits the advent of completely new ultrasound imaging modes, including shear wave elastography, electromechanical wave imaging, ultrafast doppler, ultrafast contrast imaging, and even functional ultrasound imaging of brain activity (fUltrasound) introducing Ultrasound as an emerging full-fledged neuroimaging modality. At ultrafast frame rates, it becomes possible to track in real time the transient vibrations – known as shear waves – propagating through organs. Such “human body seismology” provides quantitative maps of local tissue stiffness whose added value for diagnosis has been recently demonstrated in many fields of radiology (breast, prostate and liver cancer, cardiovascular imaging, …). Today, Supersonic Imagine company is commercializing the first clinical ultrafast ultrasound scanner, Aixplorer with real time Shear Wave Elastography. This is the first example of an ultrafast Ultrasound approach surpassing the research phase and now widely spread in the clinical medical ultrasound community with an installed base of more than 1000 Aixplorer systems in 54 countries worldwide. For blood flow imaging, ultrafast Doppler permits high-precision characterization of complex vascular and cardiac flows. It also gives ultrasound the ability to detect very subtle blood flow in very small vessels. In the brain, such ultrasensitive Doppler paves the way for fUltrasound (functional ultrasound imaging) of brain activity with unprecedented

  4. Ultrasound in Space Medicine

    NASA Technical Reports Server (NTRS)

    Dulchavsky, Scott A.; Sargsyan, A.E.

    2009-01-01

    This slide presentation reviews the use of ultrasound as a diagnostic tool in microgravity environments. The goals of research in ultrasound usage in space environments are: (1) Determine accuracy of ultrasound in novel clinical conditions. (2) Determine optimal training methodologies, (3) Determine microgravity associated changes and (4) Develop intuitive ultrasound catalog to enhance autonomous medical care. Also uses of Ultrasound technology in terrestrial applications are reviewed.

  5. High Resolution Doppler Lidar

    NASA Technical Reports Server (NTRS)

    1996-01-01

    This Grant supported the development of an incoherent lidar system to measure winds and aerosols in the lower atmosphere. During this period the following activities occurred: (1) an active feedback system was developed to improve the laser frequency stability; (2) a detailed forward model of the instrument was developed to take into account many subtle effects, such as detector non-linearity; (3) a non-linear least squares inversion method was developed to recover the Doppler shift and aerosol backscatter without requiring assumptions about the molecular component of the signal; (4) a study was done of the effects of systematic errors due to multiple etalon misalignment. It was discovered that even for small offsets and high aerosol loadings, the wind determination can be biased by as much as 1 m/s. The forward model and inversion process were modified to account for this effect; and (5) the lidar measurements were validated using rawinsonde balloon measurements. The measurements were found to be in agreement within 1-2 m/s.

  6. High Resolution Doppler Imager

    NASA Technical Reports Server (NTRS)

    Hays, Paul B.

    1999-01-01

    This report summarizes the accomplishments of the High Resolution Doppler Imager (HRDI) on UARS spacecraft during the period 4/l/96 - 3/31/99. During this period, HRDI operation, data processing, and data analysis continued, and there was a high level of vitality in the HRDI project. The HRDI has been collecting data from the stratosphere, mesosphere, and lower thermosphere since instrument activation on October 1, 1991. The HRDI team has stressed three areas since operations commenced: 1) operation of the instrument in a manner which maximizes the quality and versatility of the collected data; 2) algorithm development and validation to produce a high-quality data product; and 3) scientific studies, primarily of the dynamics of the middle atmosphere. There has been no significant degradation in the HRDI instrument since operations began nearly 8 years ago. HRDI operations are fairly routine, although we have continued to look for ways to improve the quality of the scientific product, either by improving existing modes, or by designing new ones. The HRDI instrument has been programmed to collect data for new scientific studies, such as measurements of fluorescence from plants, measuring cloud top heights, and lower atmosphere H2O.

  7. Ultrasound enhanced thrombolysis: Clinical evidence

    NASA Astrophysics Data System (ADS)

    Alexandrov, Andrei V.

    2005-04-01

    Phase II CLOTBUST randomized clinical trial (Houston, Barcelona, Edmonton, Calgary) evaluated patients with acute ischemic stroke due to intracranial occlusion and treated with intravenous tissue plasminogen activator (TPA) within 3 h of symptom onset. Randomization: monitoring with pulsed wave 2 MHz transcranial Doppler (TCD) (Target) or placebo monitoring (Control). Safety: symptomatic bleeding to the brain (sICH). Primary end-point: complete recanalization on TCD or dramatic clinical recovery by the total NIHSS score <3, or improvement by >10 NIHSS points within 2 hours after TPA bolus. All projected 126 patients were randomized 1:1 to target (median NIHSS 16) or control (NIHSS 17). sICH: 4.8% Target, 4.8% Controls. Primary end-point was achieved by 31 (49%, Target) versus 19 (30%, Control), p<0.03. At 3 months, 22 (42% Target) and 14 (29% Control) patients achieved favorable outcomes. Continuous TCD monitoring of intracranial occlusion safely augments TPA-induced arterial recanalization, and 2 MHz diagnostic ultrasound has a positive biological activity that aids systemic thrombolytic therapy. For the first time in clinical medicine, the CLOTBUST trial provides the evidence that ultrasound enhances thrombolytic activity of a drug in humans thereby confirming intense multi-disciplinary experimental research conducted worldwide for the past 30 years.

  8. Three-dimensional ultrasound imaging of the prostate

    NASA Astrophysics Data System (ADS)

    Fenster, Aaron; Downey, Donal B.

    1999-05-01

    Ultrasonography, a widely used imaging modality for the diagnosis and staging of many diseases, is an important cost- effective technique, however, technical improvements are necessary to realize its full potential. Two-dimensional viewing of 3D anatomy, using conventional ultrasonography, limits our ability to quantify and visualize most diseases, causing, in part, the reported variability in diagnosis and ultrasound guided therapy and surgery. This occurs because conventional ultrasound images are 2D, yet the anatomy is 3D; hence the diagnostician must integrate multiple images in his mind. This practice is inefficient, and may lead to operator variability and incorrect diagnoses. In addition, the 2D ultrasound image represents a single thin plane at some arbitrary angle in the body. It is difficult to localize and reproduce the image plane subsequently, making conventional ultrasonography unsatisfactory for follow-up studies and for monitoring therapy. Our efforts have focused on overcoming these deficiencies by developing 3D ultrasound imaging techniques that can acquire B-mode, color Doppler and power Doppler images. An inexpensive desktop computer is used to reconstruct the information in 3D, and then is also used for interactive viewing of the 3D images. We have used 3D ultrasound images for the diagnosis of prostate cancer, carotid disease, breast cancer and liver disease and for applications in obstetrics and gynecology. In addition, we have also used 3D ultrasonography for image-guided minimally invasive therapeutic applications of the prostate such as cryotherapy and brachytherapy.

  9. Preservation of quadrature Doppler signals from bidirectional slow blood flow close to the vessel wall using an adaptive decomposition algorithm.

    PubMed

    Zhang, Yufeng; Shi, Xinling; Zhang, Kexin; Chen, Jianhua

    2009-03-01

    A novel approach based on the phasing-filter (PF) technique and the empirical mode decomposition (EMD) algorithm is proposed to preserve quadrature Doppler signal components from bidirectional slow blood flow close to the vessel wall. Bidirectional mixed Doppler ultrasound signals, which were echoed from the forward and reverse moving blood and vessel wall, were initially separated to avoid the phase distortion of quadrature Doppler signals (which is induced from direct decomposition by the nonlinear EMD processing). Separated unidirectional mixed Doppler signals were decomposed into intrinsic mode functions (IMFs) using the EMD algorithm and the relevant IMFs that contribute to blood flow components were identified and summed to give the blood flow signals, whereby only the components from the bidirectional slow blood flow close to the vessel wall were retained independently. The complex quadrature Doppler blood flow signal was reconstructed from a combination of the extracted unidirectional Doppler blood flow signals. The proposed approach was applied to simulated and clinical Doppler signals. It is concluded from the experimental results that this approach is practical for the preservation of quadrature Doppler signal components from the bidirectional slow blood flow close to the vessel wall, and may provide more diagnostic information for the diagnosis and treatment of vascular diseases.

  10. The NPL Doppler fetal heart beat detector test facility.

    PubMed

    Bond, A D; Preston, R C

    1998-03-01

    There are many thousands of Doppler fetal heart beat detectors in medical use and many different detector manufacturers but, until recently, there has been no well-defined quantitative method for measuring the sensitivity of these detectors and, therefore, no way of directly comparing their technical performance under standardised test conditions. At NPL, we have developed a reference test facility for measuring detector sensitivity to meet the needs of manufacturers, and to comply with the requirements of an international standard (IEC 1995) that defines methods of measurement of the sensitivity of fetal heart beat detectors. The test facility has primarily been developed for detectors operating at a transmitted frequency of 2 MHz and with Doppler shifts of up to 1 kHz. The detectors are tested by directing the ultrasound beam at a small moving target being driven at a constant velocity, and then monitoring the output signal from the detector, which will be at the Doppler shift frequency. To determine the sensitivity, attenuators are inserted into the beam until the output signal is reduced to 6 dB above the noise level. The sensitivity is calculated by adding the final signal level above the noise to the total insertion loss of the attenuators in the ultrasound path and the reflection loss of the target. A crucial aspect of this calculation is the knowledge of the target strengths and characteristics. This has already been extensively studied (Preston and Bond 1997) over the frequency range of interest. The NPL test facility developed for undertaking the sensitivity measurements is described, including an assessment of the uncertainties in such a measurement and solutions to problems encountered along the way.

  11. Spectral and Spread Spectral Teleportation

    SciTech Connect

    Humble, Travis S

    2010-01-01

    We report how quantum information encoded into the spectral degree of freedom of a single-photon state is teleported using a finite spectrally entangled biphoton state. We further demonstrate how the bandwidth of a teleported waveform can be controllably and coherently dilated using a spread spectral variant of teleportation. We present analytical fidelities for spectral and spread spectral teleportation when complex-valued Gaussian states are prepared using a proposed experimental approach, and we discuss the utility of these techniques for integrating broad-bandwidth photonic qubits with narrow-bandwidth receivers in quantum communication systems.

  12. Localization of needle tip with color doppler during pericardiocentesis: In vitro validation and initial clinical application

    NASA Technical Reports Server (NTRS)

    Armstrong, G.; Cardon, L.; Vilkomerson, D.; Lipson, D.; Wong, J.; Rodriguez, L. L.; Thomas, J. D.; Griffin, B. P.

    2001-01-01

    This study evaluates a new device that uses color Doppler ultrasonography to enable real-time image guidance of the aspirating needle, which has not been possible until now. The ColorMark device (EchoCath Inc, Princeton, NJ) induces high-frequency, low-amplitude vibrations in the needle to enable localization with color Doppler. We studied this technique in 25 consecutive patients undergoing pericardiocentesis, and in vitro, in a urethane phantom with which the accuracy of color Doppler localization of the needle tip was compared with that obtained by direct measurement. Tip localization was excellent in vitro; errors axial to the ultrasound beam (velocity Doppler -0.13 +/- 0.90 mm, power Doppler -0.05 +/- 1.7 mm) were less than lateral errors (velocity -0.36 +/- 1.8 mm, power -0.02 +/- 2.8 mm). In 18 of 25 patients, the needle was identified and guided into the pericardial space with the ColorMark technique, and it allowed successful, uncomplicated drainage of fluid. Initial failures were the result of incorrect settings on the echocardiographic machine and inappropriate combinations of the needle puncture site and imaging window. This study demonstrates a novel color Doppler technique that is highly accurate at localizing a needle tip. The technique is feasible for guiding pericardiocentesis. Further clinical validation of this technique is required.

  13. Ultrasound of the Thyroid Gland

    MedlinePlus

    ... Index A-Z Ultrasound - Thyroid Thyroid ultrasound uses sound waves to produce pictures of the thyroid gland ... pictures of the inside of the body using sound waves. Ultrasound imaging, also called ultrasound scanning or ...

  14. Heating of fetal bone by diagnostic ultrasound

    NASA Astrophysics Data System (ADS)

    Doody, Claire

    Most pregnant women in the Western world undergo an ultrasound examination and so it is important to ensure that exposure of the embryo or fetus does not produce unwanted effects. It is known that ultrasound can heat tissue, especially bone, and so this thesis explores the degree to which fetal bone might be heated during a pulsed Doppler examination. This is done both by carrying out measurements and by developing computer models. Thermal measurements on human fetal thoracic vertebrae of gestational age ranging from 14 to 39 weeks are reported. The bone samples were insonated in vitro with an ultrasound beam which had power and intensity values typical of those from a clinical scanner operating in pulsed Doppler mode. Temperature rises ranging from 0.6°C to 1.8°C were observed after five minutes, with approximately 75% of the temperature rise occurring in the first minute. Two approaches to computer modelling are described. These are the heated disc technique, which is commonly used to model the temperature rise generated by an ultrasound beam, and finite element modelling, a more general approach used to obtain solutions to differential equations. The degree to which our limited knowledge of the properties of fetal tissue affect our ability to make accurate predictions of in vivo heating is explored. It is shown that the present uncertainty in the value of the thermal conductivity and attenuation coefficient of fetal bone can lead to significant uncertainty in predictions of heating. The degree to which the simplifications inherent in the heated disc model affect the results will also be discussed. The results from the models are compared with the experimental measurements in order to estimate the attenuation coefficient of the bone.

  15. Ultrasound Annual, 1983

    SciTech Connect

    Sanders, R.C.; Hill, M.C.

    1983-01-01

    The 1983 edition of Ultrasound Annual features a state-of-the-art assessment of real-time ultrasound technology and a look at improvements in real-time equipment. Chapters discuss important new obstetric applications of ultrasound in measuring fetal umbilical vein blood flow and monitoring ovarian follicular development in vivo and in vitro fertilization. Other topics covered include transrectal prostate ultrasound using a linear array system; ultrasound of the common bile duct; ultrasound in tropical diseases; prenatal diagnosis of craniospinal anomalies; scrotal ultrasonography; opthalmic ultrasonography; and sonography of the upper abdominal venous system.

  16. Noise Studies of Externally Dispersed Interferometry for Doppler Velocimetry

    SciTech Connect

    Erskine, D J; Edelstein, J; Lloyd, J; Muirhead, P

    2006-05-04

    Externally Dispersed Interferometry (EDI) is the series combination of a fixed-delay field-widened Michelson interferometer with a dispersive spectrograph. This combination boosts the spectrograph performance for both Doppler velocimetry and high resolution spectroscopy. The interferometer creates a periodic comb that multiplies against the input spectrum to create moire fringes, which are recorded in combination with the regular spectrum. Both regular and high-frequency spectral components can be recovered from the data--the moire component carries additional information that increases the signal to noise for velocimetry and spectroscopy. Here we present simulations and theoretical studies of the photon limited Doppler velocity noise in an EDI. We used a model spectrum of a 1600K temperature star. For several rotational blurring velocities 0, 7.5, 15 and 25 km/s we calculated the dimensionless Doppler quality index (Q) versus wavenumber v. This is the normalized RMS of the derivative of the spectrum and is proportional to the photon-limited Doppler signal to noise ratio.

  17. Contrast-enhanced ultrasound in ovarian tumors – diagnostic parameters: method presentation and initial experience

    PubMed Central

    MAXIM, ANITA-ROXANA; BADEA, RADU; TAMAS, ATILLA; TRAILA, ALEXANDRU

    2013-01-01

    The aim of this paper is to discuss and illustrate the use of contrast-enhanced ultrasound in evaluating ovarian tumors compared to conventional ultrasound, Doppler ultrasound and the histopathological analysis and suggest how this technique may best be used to distinguish benign from malignant ovarian masses. We present the method and initial experience of our center by analyzing the parameters used in contrast-enhanced ultrasound in 6 patients with ovarian tumors of uncertain etiology. For examination we used a Siemens ultrasound machine with dedicated contrast software and the contrast agent SonoVue, Bracco. The patients underwent conventional ultrasound, Doppler ultrasound and i.v. administration of the contrast agent. The parameters studied were: inflow of contrast (rise time), time to peak enhancement, mean transit time. The series of patients is part of an extensive prospective PhD study aimed at elaborating a differential diagnosis protocol for benign versus malignant ovarian tumors, by validating specific parameters for contrast-enhanced ultrasound. Although the method is currently used with great success in gastroenterology, urology and senology, its validation in gynecology is still in the early phases. Taking into consideration that the method is minimally invasive and much less costly that CT/MRI imaging, demonstrating its utility in oncologic gynecology would be a big step in preoperative evaluation of these cases. PMID:26527912

  18. Ultrasound in anesthesia: applying scientific principles to clinical practice.

    PubMed

    Falyar, Christian R

    2010-08-01

    The use of ultrasound as an adjunct to invasive anesthesia procedures is becoming commonplace. The U.S. Agency for Health Care Quality and the United Kingdom National Institute for Clinical Excellence have identified the role of ultrasound in improving patient safety. Numerous studies have demonstrated the benefits of ultrasound, yet there have also been articles inferring it may not offer additional benefits to traditional landmark techniques. The major disadvantage often cited is that success is user-dependent, and using ultrasound is a unique skill that requires training and experience to become proficient. Modern ultrasound systems incorporate 2 sound technologies to provide users with specific information about what is being viewed. Brightness mode imaging and pulsed-wave Doppler can be combined to reduce potential complications associated with central venous access and regional anesthesia. Human tissue is also an important factor in ultrasound imaging. The different densities of soft tissues, bone, fluid, and air all interact with sound, creating distinctive images that can aid and potentially hinder accuracy. Comprehension of basic ultrasound principles and how it is affected by tissue will enable anesthetists to better understand what is being seen and reduce the potential for errors.

  19. Attenuated Vector Tomography -- An Approach to Image Flow Vector Fields with Doppler Ultrasonic Imaging

    SciTech Connect

    Huang, Qiu; Peng, Qiyu; Huang, Bin; Cheryauka, Arvi; Gullberg, Grant T.

    2008-05-15

    The measurement of flow obtained using continuous wave Doppler ultrasound is formulated as a directional projection of a flow vector field. When a continuous ultrasound wave bounces against a flowing particle, a signal is backscattered. This signal obtains a Doppler frequency shift proportional to the speed of the particle along the ultrasound beam. This occurs for each particle along the beam, giving rise to a Doppler velocity spectrum. The first moment of the spectrum provides the directional projection of the flow along theultrasound beam. Signals reflected from points further away from the detector will have lower amplitude than signals reflected from points closer to the detector. The effect is very much akin to that modeled by the attenuated Radon transform in emission computed tomography.A least-squares method was adopted to reconstruct a 2D vector field from directional projection measurements. Attenuated projections of only the longitudinal projections of the vector field were simulated. The components of the vector field were reconstructed using the gradient algorithm to minimize a least-squares criterion. This result was compared with the reconstruction of longitudinal projections of the vector field without attenuation. Ifattenuation is known, the algorithm was able to accurately reconstruct both components of the full vector field from only one set of directional projection measurements. A better reconstruction was obtained with attenuation than without attenuation implying that attenuation provides important information for the reconstruction of flow vector fields.This confirms previous work where we showed that knowledge of the attenuation distribution helps in the reconstruction of MRI diffusion tensor fields from fewer than the required measurements. In the application of ultrasound the attenuation distribution is obtained with pulse wave transmission computed tomography and flow information is obtained with continuous wave Doppler.

  20. Micro-Doppler frequency comb generation by rotating wire scatterers

    NASA Astrophysics Data System (ADS)

    Kozlov, V.; Filonov, D.; Yankelevich, Y.; Ginzburg, P.

    2017-03-01

    Electromagnetic scattering in accelerating reference frames inspires a variety of phenomena, requiring employment of general relativity for their description. While the 'quasi-stationary field' analysis could be applied to slowly-accelerating bodies as a first-order approximation, the scattering problem remains fundamentally nonlinear in boundary conditions, giving rise to multiple frequency generation (micro-Doppler shifts). Here a frequency comb, generated by an axially rotating subwavelength (cm-range) wires is analyzed theoretically and observed experimentally by illuminating the system with a 2 GHz carrier wave. Highly accurate 'lock in' detection scheme enables factorization of the carrier and observation of multiple peaks in a comb. The Hallen integral equation is employed for deriving the currents induced on the scatterer and a set of coordinate transformations, connecting laboratory and rotating frames, is applied in order to make analytical predictions of the spectral positions and amplitudes of the frequency comb peaks. Numeric simulations of the theoretic framework reveal the dependence of the micro-Doppler peaks on the wire's length and its axis of rotation. Unique spectral signature of micro-Doppler shifts could enable resolving internal structures of scatterers and mapping their accelerations in space, which is valuable for a variety of applications spanning from targets identification to stellar radiometry.

  1. Doppler Spectra and Estimated Windspeed of a Violent Tornado.

    NASA Astrophysics Data System (ADS)

    Zrni, Dusan; Burgess, Donald W.; Hennington, Larry

    1985-10-01

    Presented in this Paper are Doppler spectra of a very large tornado that occurred on 22 May 1981 near Binger, Oklahoma. Tracking of the tornado was accomplished with the help of a novel `polar spectra display.' Bimodal tornado spectral signatures (TSS) were observed in about 40 scans. Direct measurements of maximum velocities from spectral skirts yielded a maximum tangential speed of 80 m s1 (90 m s1 relative to ground). A diameter of 1 km at 200 m above ground was deduced from a simplified model. Radial centrifuging of radar targets was estimated to be about 20 m s1. With simple assumptions for radar target sizes and summation of forces, a beamwidth average convergence value of about 2.5 × 102 s1 was calculated for the tornado boundary layer.Tornado damage to trees and structures was subjectively rated on the Fujita damage scale. The windspeed range associated with the damage scale agreed well with the Doppler-estimated maximum windspeed when the tornado was large (1 km diameter). However, as the tornado diameter decreased, the Doppler-derived windspeed considerably underestimated that associated with the damage scale.

  2. Doppler lidar signal and turbulence study

    NASA Technical Reports Server (NTRS)

    Frost, W.; Huang, K. H.

    1983-01-01

    Wind fields were measured with the ground-based NASA/MSFC lidar are compared with the in situ NASA RB-57 aircraft measurements. The mean wind fields, the turbulence intensities, and the turbulence spectra determined from measurements by both systems are in very good agreement. Turbulence intensities and spectra were calculated from the fluctuations with time in the radial wind speed component. The second moment or Doppler frequency spectral width of the lidar measurements was also compared with turbulence intensities measured by the aircraft. These second moments could only be resolved at the very low altitudes (in three range bins). Turbulence intensities estimated from the spectral width data were an order of magnitude higher than those measured by the aircraft. An interesting boundary layer evolved during the progress of the experiment. The breakup of a stable boundary layer resulted in winds blowing in one direction above 600 m msl and in the opposite direction below that level. Both the aircraft and the lidar systems clearly identified this unusual boundary layer flow and showed the identical trends.

  3. Assessment of the effect of vessel curvature on Doppler measurements in steady flow.

    PubMed

    Balbis, S; Guiot, C; Roatta, S; Arina, R; Todros, T

    2004-05-01

    Blood vessel curvature is responsible for the appearance of nonaxial velocity components and for minor changes in the pattern of the axial flow. All the velocity components are expected to contribute to the Doppler signal produced by the ultrasound (US) backscattered by the insonated blood cells, the axial velocity, contributing to the actual volumetric blood flow, and the transverse velocity, causing the recirculating vortices. A detailed, separate analysis of the velocity components is, therefore, mandatory to quantify how vessel curvature can affect results and clinical diagnosis. Both experimental in vitro measures and numerical simulations were performed on a curved tube and the Doppler power spectra so obtained were compared. The satisfactorily agreement of the above spectra shows that the nonaxial velocity components are easily detectable with clinical equipment and that their amplitude, as expected, is not negligible and can bias Doppler measurements and resulting clinical diagnosis.

  4. Potential use of Doppler perfusion index in detection of occult liver metastases from colorectal cancer

    PubMed Central

    Patrlj, Leonardo; Bušić, Željko; Kolovrat, Marijan; Rakić, Mislav; Kliček, Robert; Židak, Marcel; Stipančić, Igor

    2014-01-01

    Many clinical and preclinical studies demonstrated that measurements of liver hemodynamic [Doppler perfusion index (DPI)] may be used to accurately diagnose and predict liver metastases from primary colorectal cancer in a research setting. However, Doppler measurements have some serious limitations when applied to general population. Ultrasound is very operator-dependent, and requires skilled examiners. Also, many conditions may limit the use of Doppler ultrasound and ultrasound in general, such as the presence of air in digestive tract, cardiac arrhythmias, vascular anomalies, obesity and other conditions. Therefore, in spite of the results from clinical studies, its value may be limited in everyday practice. On the contrary, scientific research of the DPI in detection of liver metastases is of great importance, since current research speaks strongly for the presence of systemic vasoactive substance responsible for observed hemodynamic changes. Identification of such a systemic vasoactive substance may lead to the development of a simple and reproducible laboratory test that may reliably identify the presence of occult liver metastases and therefore increase the success of adjuvant chemotherapy through better selection of patients. Further research in this subject is therefore of great importance. PMID:25392837

  5. Virtual Guidance Ultrasound: A Tool to Obtain Diagnostic Ultrasound for Remote Environments

    NASA Technical Reports Server (NTRS)

    Caine,Timothy L.; Martin David S.; Matz, Timothy; Lee, Stuart M. C.; Stenger, Michael B.; Platts, Steven H.

    2012-01-01

    Astronauts currently acquire ultrasound images on the International Space Station with the assistance of real-time remote guidance from an ultrasound expert in Mission Control. Remote guidance will not be feasible when significant communication delays exist during exploration missions beyond low-Earth orbit. For example, there may be as much as a 20- minute delay in communications between the Earth and Mars. Virtual-guidance, a pre-recorded audio-visual tutorial viewed in real-time, is a viable modality for minimally trained scanners to obtain diagnostically-adequate images of clinically relevant anatomical structures in an autonomous manner. METHODS: Inexperienced ultrasound operators were recruited to perform carotid artery (n = 10) and ophthalmic (n = 9) ultrasound examinations using virtual guidance as their only instructional tool. In the carotid group, each each untrained operator acquired two-dimensional, pulsed, and color Doppler of the carotid artery. In the ophthalmic group, operators acquired representative images of the anterior chamber of the eye, retina, optic nerve, and nerve sheath. Ultrasound image quality was evaluated by independent imaging experts. RESULTS: Eight of the 10 carotid studies were judged to be diagnostically adequate. With one exception the quality of all the ophthalmic images were adequate to excellent. CONCLUSION: Diagnostically-adequate carotid and ophthalmic ultrasound examinations can be obtained by untrained operators with instruction only from an audio/video tutorial viewed in real time while scanning. This form of quick-response-guidance, can be developed for other ultrasound examinations, represents an opportunity to acquire important medical and scientific information for NASA flight surgeons and researchers when trained medical personnel are not present. Further, virtual guidance will allow untrained personnel to autonomously obtain important medical information in remote locations on Earth where communication is

  6. Inferring spectral characteristics of the Hα spectral line observed by the DOT Lyot filter

    NASA Astrophysics Data System (ADS)

    Koza, J.; Rybák, J.; Gömöry, P.; Kučera, A.

    2014-04-01

    A tunable Lyot filter can serve as a spectroscopic device rendering wide-field 2-D pseudospectroscopy of solar structures and follow-up crude reconstruction of a spectral line profile at each pixel within the field of view. We developed a method of inferring of the Doppler shift, the core intensity, the core width, and the core asymmetry of the Hα spectral line observed by the Lyot filter installed on the Dutch Open Telescope (DOT). The spectral characteristics are inferred through the fitting of five intensity samples, separated from each other by 0.35 Å, by a 4th-order polynomial, a Gaussian, and a parabola. We use the atlas Hα profile as a reference in estimating deviations of the derived spectral characteristics. The Gaussian is the most preferable means for measurements of the Doppler shift with deviations smaller than 1 km s-1. When using the 4th-order polynomial, deviations are within the interval ±2.5 km s-1, but it renders comparable deviations of the core intensity and the width as the Gaussian. The deviations are largely insensitive to the shape of the filter transmission, but depend mostly non-linearly on the Doppler shift. Therefore, they do not cancel out if the spectral characteristics are represented by their relative variations. Results can be used as corrections of spectral characteristics extracted from area-averaged Hα profiles acquired by the DOT Lyot filter.

  7. Clinical ultrasound physics.

    PubMed

    Abu-Zidan, Fikri M; Hefny, Ashraf F; Corr, Peter

    2011-10-01

    Understanding the basic physics of ultrasound is essential for acute care physicians. Medical ultrasound machines generate and receive ultrasound waves. Brightness mode (B mode) is the basic mode that is usually used. Ultrasound waves are emitted from piezoelectric crystals of the ultrasound transducer. Depending on the acoustic impedance of different materials, which depends on their density, different grades of white and black images are produced. There are different methods that can control the quality of ultrasound waves including timing of ultrasound wave emission, frequency of waves, and size and curvature of the surface of the transducer. The received ultrasound signal can be amplified by increasing the gain. The operator should know sonographic artifacts which may distort the studied structures or even show unreal ones. The most common artifacts include shadow and enhancement artifacts, edge artifact, mirror artifact and reverberation artifact.

  8. Transvaginal ultrasound (image)

    MedlinePlus

    Transvaginal ultrasound is a method of imaging the genital tract in females. A hand held probe is inserted directly ... vaginal cavity to scan the pelvic structures, while ultrasound pictures are viewed on a monitor. The test ...

  9. Abdominal ultrasound (image)

    MedlinePlus

    Abdominal ultrasound is a scanning technique used to image the interior of the abdomen. Like the X-ray, MRI, ... it has its place as a diagnostic tool. Ultrasound scans use high frequency sound waves to produce ...

  10. Prenatal ultrasound - slideshow

    MedlinePlus

    ... page: //medlineplus.gov/ency/presentations/100197.htm Prenatal ultrasound - series—Procedure, part 1 To use the sharing ... Editorial team. Related MedlinePlus Health Topics Prenatal Testing Ultrasound A.D.A.M., Inc. is accredited by ...

  11. Ultrasonic Doppler vibrometry: measurement of left ventricular wall vibrations associated with coronary artery disease.

    PubMed

    Sikdar, Siddhartha; Beach, Kirk W; Goldberg, Steven L; Lidstrom, Matthew S; Kim, Yongmin

    2006-01-01

    We have developed a new method of detecting coronary artery stenoses that uses Doppler ultrasound to measure minute local vibrations in the cardiac wall associated with post-stenotic flow turbulence. In this paper, we present the results of a preliminary clinical study to evaluate the efficacy of this method for detecting coronary artery disease (CAD) using coronary angiography as the gold standard. The study population consisted of 34 patients clinically-indicated for coronary angiography. Based on the catheterization reports, the patients were divided into three categories: severe (obstructive CAD, typically with >70% diameter reduction), moderate (non-obstructive CAD, typically with <50% diameter reduction or diffuse atherosclerosis), and normal (no angiographic evidence of CAD). A diastolic myocardial vibration index (DMVI) was calculated as the ratio of the normalized periodogram spectral energy in the 100~800-Hz frequency band of the instantaneous wall velocity in early diastole to a baseline value during diastasis. The DMVI was significantly higher in severe CAD patients (21.2 +/- 3.2 dB) compared to moderate CAD (17.5 +/- 3.5 dB) and normal (11.2 +/- 4.8 dB). The differences between each of the categories were statistically significant (p<0.05). Severe CAD patients could be distinguished from normal with a sensitivity of 91.7% and specificity of 83.3%. We believe that this method could potentially be developed into a low-cost and accurate test for diagnosis and screening for coronary artery stenosis.

  12. Ultrasound Imaging System Video

    NASA Technical Reports Server (NTRS)

    2002-01-01

    In this video, astronaut Peggy Whitson uses the Human Research Facility (HRF) Ultrasound Imaging System in the Destiny Laboratory of the International Space Station (ISS) to image her own heart. The Ultrasound Imaging System provides three-dimension image enlargement of the heart and other organs, muscles, and blood vessels. It is capable of high resolution imaging in a wide range of applications, both research and diagnostic, such as Echocardiography (ultrasound of the heart), abdominal, vascular, gynecological, muscle, tendon, and transcranial ultrasound.

  13. Effect of the optical system on the Doppler spectrum in laser-feedback interferometry.

    PubMed

    Mowla, Alireza; Nikolić, Milan; Taimre, Thomas; Tucker, John R; Lim, Yah Leng; Bertling, Karl; Rakić, Aleksandar D

    2015-01-01

    We present a comprehensive analysis of factors influencing the morphology of the Doppler spectrum obtained from a laser-feedback interferometer. We explore the effect of optical system parameters on three spectral characteristics: central Doppler frequency, broadening, and signal-to-noise ratio. We perform four sets of experiments and replicate the results using a Monte Carlo simulation calibrated to the backscattering profile of the target. We classify the optical system parameters as having a strong or weak influence on the Doppler spectrum. The calibrated Monte Carlo approach accurately reproduces experimental results, and allows one to investigate the detailed contribution of system parameters to the Doppler spectrum, which are difficult to isolate in experiment.

  14. Tracking driver's heart rate by continuous-wave Doppler radar.

    PubMed

    Kwang Jin Lee; Chanki Park; Boreom Lee

    2016-08-01

    Developing driving safety system with medical assistance devices for preventing accidents has become a major social issue in recent year. These devices have been developed using electrocardiogram (ECG) and photoplethysmogram (PPG) for measuring the heart rate (HR). However, driver should directly contact with the sensor for monitoring the HR. Recently, non-contact system based on continuous-wave Doppler radar has widely studied for monitoring HR. The periodogram by Fast Fourier Transform (FFT) was used for estimating HR. However, if motion artifacts by movement of driver and vehicle vibration contaminate the radar signal, we cannot find spectral peak of HR using FFT. In this paper, we propose a method using multiple signal classification (MUSIC) for estimating HR. We compared MUSIC algorithms with a commonly used FFT method using real experiment data while driving. The results indicate that our proposed method can estimate HR accurately from received radar Doppler signal with motion artifacts.

  15. Atomic Auger Doppler effects upon emission of fast photoelectrons.

    PubMed

    Simon, Marc; Püttner, Ralph; Marchenko, Tatiana; Guillemin, Renaud; Kushawaha, Rajesh K; Journel, Loïc; Goldsztejn, Gildas; Piancastelli, Maria Novella; Ablett, James M; Rueff, Jean-Pascal; Céolin, Denis

    2014-06-06

    Studies of photoemission processes induced by hard X-rays including production of energetic electrons have become feasible due to recent substantial improvement of instrumentation. Novel dynamical phenomena have become possible to investigate in this new regime. Here we show a significant change in Auger emission following 1s photoionization of neon, which we attribute to the recoil of the Ne ion induced by the emission of a fast photoelectron. Because of the preferential motion of the ionized Ne atoms along two opposite directions, an Auger Doppler shift is revealed, which manifests itself as a gradual broadening and doubling of the Auger spectral features. This Auger Doppler effect should be a general phenomenon in high-energy photoemission of both isolated atoms and molecules, which will have to be taken into account in studies of other recoil effects such as vibrational or rotational recoil in molecules, and may also have consequences in measurements in solids.

  16. Microwave Doppler reflectometer system in the Experimental Advanced Superconducting Tokamak.

    PubMed

    Zhou, C; Liu, A D; Zhang, X H; Hu, J Q; Wang, M Y; Li, H; Lan, T; Xie, J L; Sun, X; Ding, W X; Liu, W D; Yu, C X

    2013-10-01

    A Doppler reflectometer system has recently been installed in the Experimental Advanced Superconducting (EAST) Tokamak. It includes two separated systems, one for Q-band (33-50 GHz) and the other for V-band (50-75 GHz). The optical system consists of a flat mirror and a parabolic mirror which are optimized to improve the spectral resolution. A synthesizer is used as the source and a 20 MHz single band frequency modulator is used to get a differential frequency for heterodyne detection. Ray tracing simulations are used to calculate the scattering location and the perpendicular wave number. In EAST last experimental campaign, the Doppler shifted signals have been obtained and the radial profiles of the perpendicular propagation velocity during L-mode and H-mode are calculated.

  17. Application of FFT analyzed cardiac Doppler signals to fuzzy algorithm.

    PubMed

    Güler, Inan; Hardalaç, Firat; Barişçi, Necaattin

    2002-11-01

    Doppler signals, recorded from the output of tricuspid, mitral, and aorta valves of 60 patients, were transferred to a personal computer via 16-bit sound card. The fast Fourier transform (FFT) method was applied to the recorded signal from each patient. Since FFT method inherently cannot offer a good spectral resolution at highly turbulent blood flows, it sometimes leads to wrong interpretation of cardiac Doppler signals. In order to avoid this problem, firstly six known diseased heart signals such as hypertension, mitral stenosis, mitral failure, tricuspid stenosis, aorta stenosis, aorta insufficiency were introduced to fuzzy algorithm. Then, the unknown heart diseases from 15 patients were applied to the same fuzzy algorithm in order to detect the kinds of diseases. It is observed that the fuzzy algorithm gives true results for detecting the kind of diseases.

  18. Theoretical model for Sub-Doppler Cooling with EIT System

    NASA Astrophysics Data System (ADS)

    He, Peiru; Tengdin, Phoebe; Anderson, Dana; Rey, Ana Maria; Holland, Murray

    2016-05-01

    We propose a of sub-Doppler cooling mechanism that takes advantage of the unique spectral features and extreme dispersion generated by the so-called Electromagnetically Induced Transparency (EIT) effect, a destructive quantum interference phenomenon experienced by atoms with Lambda-shaped energy levels when illuminated by two light fields with appropriate frequencies. By detuning the probe lasers slightly from the ``dark resonance'', we observe that atoms can be significantly cooled down by the strong viscous force within the transparency window, while being just slightly heated by the diffusion caused by the small absorption near resonance. In contrast to polarization gradient cooling or EIT sideband cooling, no external magnetic field or external confining potential are required. Using a semi-classical method, analytical expressions, and numerical simulations, we demonstrate that the proposed EIT cooling method can lead to temperatures well below the Doppler limit. This work is supported by NSF and NIST.

  19. Endobronchial ultrasound.

    PubMed

    Falcone, Franco; Fois, Flavio; Grosso, Daniele

    2003-01-01

    Complex technical problems interfered with the application of thoracic ultrasound (US) for studies and clinical research. Moreover, in contrast to radiologists, cardiologists, gastroenterologists, internists, obstetricians, gynecologists and others, pulmonologists were not trained in the basics of US images. However, endoscopic US methods were developed in the last 20 years and these methods also provided important results for pulmonologists. As soon as the technical problems interfering with US application in air-containing spaces were solved, endobronchial US (EBUS) became a valuable technique as well. With EBUS, the delicate multilayer structure of the tracheobronchial wall can be analyzed. This knowledge became decisive for the management of early cancer in the central airways. These lesions can undergo local treatment instead of surgical intervention if the bronchial cartilage is intact and if the adjacent lymph nodes are not involved. EBUS proved valuable as well for the staging of more advanced lung cancer, especially with regard to endoluminal, intramural and extraluminal tumor spread. Endobronchial endosonographers are able to diagnose mediastinal lymph nodes similar to the experience of gastrointestinal endosonographers. EBUS-guided transbronchial needle aspiration (TBNA) improved the results of N-staging of lung cancer, especially in difficult lymph node levels without any clear endoscopic landmarks. The possibility of identifying N2 and N3 stages by means of a nonsurgical procedure can modify the management of lung cancer and decrease the number of unnecessary surgical interventions. EBUS can reduce the need for more invasive procedures such as thoracoscopy or mediastinoscopy. It is also useful for biopsying peripheral lesions or solitary pulmonary nodules instead of fluoroscopic guidance and also plays an important role in the strategy of interventional endoscopy.

  20. Right Ventricular Tissue Doppler in Space Flight

    NASA Technical Reports Server (NTRS)

    Garcia, Kathleen M.; Hamilton, Douglas R.; Sargsyan, Ashot E.; Ebert, Douglas; Martin, David S.; Barratt, Michael R.; Martin, David S.; Bogomolov, Valery V.; Dulchavsky, Scott A.; Duncan, J. Michael

    2010-01-01

    The presentation slides review normal physiology of the right ventricle in space, general physiology of the right ventricle; difficulties in imaging the heart in space, imaging methods, tissue Doppler spectrum, right ventricle tissue Doppler, and Rt Tei Index.

  1. Understanding Doppler Broadening of Gamma Rays

    SciTech Connect

    Rawool-Sullivan, Mohini; Sullivan, John P.

    2014-07-03

    Doppler-broadened gamma ray peaks are observed routinely in the collection and analysis of gamma-ray spectra. If not recognized and understood, the appearance of Doppler broadening can complicate the interpretation of a spectrum and the correct identification of the gamma ray-emitting material. We have conducted a study using a simulation code to demonstrate how Doppler broadening arises and provide a real-world example in which Doppler broadening is found. This report describes that study and its results.

  2. Ultrasound biomicroscopy in mouse cardiovascular development

    NASA Astrophysics Data System (ADS)

    Turnbull, Daniel H.

    2001-05-01

    The mouse is the preferred animal model for studying mammalian cardiovascular development and many human congenital heart diseases. Ultrasound biomicroscopy (UBM), utilizing high-frequency (40-50-MHz) ultrasound, is uniquely capable of providing in vivo, real-time microimaging and Doppler blood velocity measurements in mouse embryos and neonates. UBM analyses of normal and abnormal mouse cardiovascular function will be described to illustrate the power of this microimaging approach. In particular, real-time UBM images have been used to analyze dimensional changes in the mouse heart from embryonic to neonatal stages. UBM-Doppler has been used recently to examine the precise timing of onset of a functional circulation in early-stage mouse embryos, from the first detectable cardiac contractions. In other experiments, blood velocity waveforms have been analyzed to characterize the functional phenotype of mutant mouse embryos having defects in cardiac valve formation. Finally, UBM has been developed for real-time, in utero image-guided injection of mouse embryos, enabling cell transplantation and genetic gain-of-function experiments with transfected cells and retroviruses. In summary, UBM provides a unique and powerful approach for in vivo analysis and image-guided manipulation in normal and genetically engineered mice, over a wide range of embryonic to neonatal developmental stages.

  3. Ultrasound biomicroscopy in mouse cardiovascular development

    NASA Astrophysics Data System (ADS)

    Turnbull, Daniel H.

    2004-05-01

    The mouse is the preferred animal model for studying mammalian cardiovascular development and many human congenital heart diseases. Ultrasound biomicroscopy (UBM), utilizing high-frequency (40-50-MHz) ultrasound, is uniquely capable of providing in vivo, real-time microimaging and Doppler blood velocity measurements in mouse embryos and neonates. UBM analyses of normal and abnormal mouse cardiovascular function will be described to illustrate the power of this microimaging approach. In particular, real-time UBM images have been used to analyze dimensional changes in the mouse heart from embryonic to neonatal stages. UBM-Doppler has been used recently to examine the precise timing of onset of a functional circulation in early-stage mouse embryos, from the first detectable cardiac contractions. In other experiments, blood velocity waveforms have been analyzed to characterize the functional phenotype of mutant mouse embryos having defects in cardiac valve formation. Finally, UBM has been developed for real-time, in utero image-guided injection of mouse embryos, enabling cell transplantation and genetic gain-of-function experiments with transfected cells and retroviruses. In summary, UBM provides a unique and powerful approach for in vivo analysis and image-guided manipulation in normal and genetically engineered mice, over a wide range of embryonic to neonatal developmental stages.

  4. Ultrasound anatomy and normal ECD of the kidney.

    PubMed

    Rosi, Paolo; Del Zingaro, Michele; Porena, Massimo

    2005-03-01

    The adult kidney is studied using convex-array probes with a frequency of 3.5 MHz, whereas in children higher frequencies are advisable (5 MHz). The study of the organ may be carried out with three possible approaches (access routes): abdominal (anterior), lumbar (lateral), dorsal (posterior). For a correct and complete study of the renal echostructure 5 fundamental parameters need to be evaluated: shape, size, parenchymal echotexture, renal sinus and renal hilum. The most common anatomical variants need to be identified and namely, dromedary humps, foetal lobation, hypertrophied column of Berten, hypertrophied renal tubercles and labia. The use of colour-Doppler ultrasound equipment permits assessment of the main renal arteries, the segmentary branches at the level of the hilum, the interlobar arteries, the arcuate arteries, and the interlobular arteries (inconsistently). Colour and duplex ultrasound enable identification of flow signals from arteries that are not directly visible at B-mode sonography, since frequency resolution (related to the Doppler-shift) is greater than spatial and contrast resolution. Power doppler provides a detailed visualisation of the distribution of vascular structures and blood circulation in the different regions of the kidney parenchyma, affording a perfusion study similar to angiographic parenchymography. Unlike colour Doppler, power Doppler allows identification of the cortical circulation. The Doppler pattern of the renal arteries is typical of arteries with parenchyma destination, which show a systolic peak and a well-depicted diastolic curve due to low peripheral resistance. The parameters to be analysed are peak systolic velocity, acceleration time, pulsatility index, and resistive index.

  5. Tissue perfusion measurements: multiple-exposure laser speckle analysis generates laser Doppler-like spectra.

    PubMed

    Thompson, Oliver B; Andrews, Michael K

    2010-01-01

    Variations in skin perfusion are easily detected by laser speckle contrast maps, but a robust interpretation of the information has been lacking. We show that multiple-exposure laser speckle methods produce the same spectral information as laser Doppler methods when applied to targets with embedded moving scatterers. This enables laser speckle measurements to be interpreted more quantitatively. We do this by using computer simulation of speckle data, and by experimental measurements on Brownian motion and skin perfusion using a laser Doppler system and a multiple-exposure laser speckle system. The power spectral density measurements of the light fluctuations derived using both techniques are exactly equivalent. Dermal perfusion can therefore be measured by laser Doppler or laser speckle contrast methods. In particular, multiexposure laser speckle can be rapidly processed to generate a full-field map of the perfusion index proportional to the concentration and mean velocity of red blood cells.

  6. The Doppler Effect--A New Approach

    ERIC Educational Resources Information Center

    Allen, J.

    1973-01-01

    Discusses the Doppler effect as it applies to different situations, such as a stationary source of sound with the observer moving, a stationary observer, and the sound source and observer both moving. Police radar, satellite surveillance radar, radar astronomy, and the Doppler navigator, are discussed as applications of Doppler shift. (JR)

  7. Doppler observations of solar rotation

    NASA Technical Reports Server (NTRS)

    Scherrer, P. H.

    1980-01-01

    Daily observations of the photospheric equatorial rotation rate using the Doppler effect mode at the Sanford Solar Observatory are presented. These observations show no variations in the rotation rate that exceed the observational error of about one percent. The average rotation rate is indistinguishable from that of sunspots and large scale magnetic field structures.

  8. Doppler observations of solar rotation

    NASA Technical Reports Server (NTRS)

    Scherrer, P. H.; Wilcox, J. M.

    1980-01-01

    Daily observations of the photospheric equatorial rotation rate using the Doppler effect are made at the Stanford Solar Observatory. These observations show no variations in the rotation rate that exceed the observational error of about 1%. The average rotation rate is indistinguishable from that of sunspots and large-scale magnetic field structures.

  9. Doppler Imaging of EI Eridani

    NASA Astrophysics Data System (ADS)

    Washuettl, Albert; Strassmeier, Klaus G.; Collier-Cameron, Andrew

    We present Doppler images of the rapidly rotating active close binary star EI Eridani. Several Doppler images have been produced since 1984 making use of different versions of the Doppler imaging technique. They all show high-latitude spots surrounding or covering the rotational pole as well as some smaller spots on lower latitudes. The high-latitude/polar spot seems to be long-lived (at least a decade) but changes its shape on comparatively short timescales (of the order of one month). From time to time spots along the stellar equator also occur, but their lifetimes tend to be relatively short (weeks). Furthermore, long-term photometric observations revealed the existence of a magnetic cycle which has been estimated to be around 11 years. We also present time-resolved Doppler images from EI Eri obtained at McMath/NSO in fall 1996 during 70 consecutive nights. The final aim of this program is to investigate the spot evolution over the whole activity cycle.

  10. Spaceborne Simulations of Two Direct-Detection Doppler Lidar Techniques

    NASA Technical Reports Server (NTRS)

    McGill, Matthew J.; Li, Steve X.

    1998-01-01

    Direct-detection (or incoherent) lidar is now a proven technique for measuring winds in the atmosphere. Over the last few years, several types of direct-detection lidar have evolved. These methods rely on Fabry-Perot interferometers(also termed etalons) or other narrow-passband filters to provide the required spectral resolution. One method, now called the edge (EDG) technique, uses a sharply-sloping filter and measures changes in the filter transmission caused by Doppler shifting of the laser wavelength. A variation of the EDG method, called the double-edge (DEDG) technique, uses two filters. The molecular DEDG method was first demonstrated by Chanin et al. for stratospheric measurements and more recently Korb et al. successfully demonstrated the aerosol DEDG through the troposphere. A second method, here termed the multi-channel (MC) technique, measures Doppler shifts by observing angular displacement of a Fabry-Perot fringe in a spatially resolving detector. The EDG technique thus employs the Fabry-Perot to convert the frequency shift into an amplitude signal, while the MC technique uses the Fabry-Perot to resolve the spectral signature which is then fitted to determine the centroid. The focus of this presentation is on the DEDG and MC methods because these are viewed as the current state of the art in direct-detection lidar. Successful ground-based demonstrations of direct-detection wind measurements have resulted in proposals for spaceborne systems. With this new emphasis on spaceborne systems comes the need for accurate prediction of spaceborne direct-detection Doppler lidar performance. Previously, the EDG and MC methods have been compared although only for aerosol Doppler systems. A recent paper by McGill and Spinhirne compares the DEDG and MC methods in a non-system specific manner for both the aerosol and molecular Doppler systems. The purpose of this presentation is to extend the previous work of McGill and Spinhirne to examine the performance of

  11. A cavernous hemangioma of the thyroid gland: First documentation by ultrasound of a rare pathology.

    PubMed

    Gutzeit, Andreas; Stuckmann, Gerd; Tosoni, Ivo; Erdin, Dieter; Binkert, Christoph A

    2011-01-01

    Hemangioma of the thyroid gland is an extremely rare condition. We report a case of a primary cavernous hemangioma in the left lobe of the thyroid gland in an 84-year-old woman. Ultrasound examination of the lesion showed an inhomogeneous and hypoechoic nodule that was well demarcated from the rest of the left lobe and hypovascular on color Doppler ultrasound. Ultrasound-guided fine-needle aspiration was performed. The cytologic differential diagnosis included an anaplastic carcinoma of the thyroid gland. After hemithyroidectomy, the final diagnosis was a benign hemangioma of the thyroid gland.

  12. Blood flow velocity in the popliteal vein using transverse oscillation ultrasound

    NASA Astrophysics Data System (ADS)

    Bechsgaard, Thor; Hansen, Kristoffer Lindskov; Brandt, Andreas Hjelm; Holbek, Simon; Lönn, Lars; Strandberg, Charlotte; Bækgaard, Niels; Nielsen, Michael Bachmann; Jensen, Jørgen Arendt

    2016-04-01

    Chronic venous disease is a common condition leading to varicose veins, leg edema, post-thrombotic syndrome and venous ulcerations. Ultrasound (US) is the main modality for examination of venous disease. Color Doppler and occasionally spectral Doppler US (SDUS) are used for evaluation of the venous flow. Peak velocities measured by SDUS are rarely used in a clinical setting for evaluating chronic venous disease due to inadequate reproducibility mainly caused by the angle dependency of the estimate. However, estimations of blood velocities are of importance in characterizing venous disease. Transverse Oscillation US (TOUS), a non-invasive angle independent method, has been implemented on a commercial scanner. TOUS's advantage compared to SDUS is a more elaborate visualization of complex flow. The aim of this study was to evaluate, whether TOUS perform equal to SDUS for recording velocities in the veins of the lower limbs. Four volunteers were recruited for the study. A standardized flow was provoked with a cuff compression-decompression system placed around the lower leg. The average peak velocity in the popliteal vein of the four volunteers was 151.5 cm/s for SDUS and 105.9 cm/s for TOUS (p <0.001). The average of the peak velocity standard deviations (SD) were 17.0 cm/s for SDUS and 13.1 cm/s for TOUS (p <0.005). The study indicates that TOUS estimates lower peak velocity with improved SD when compared to SDUS. TOUS may be a tool for evaluation of venous disease providing quantitative measures for the evaluation of venous blood flow.

  13. Comparison of carotid artery blood velocity measurements by vector and standard Doppler approaches.

    PubMed

    Tortoli, Piero; Lenge, Matteo; Righi, Daniele; Ciuti, Gabriele; Liebgott, Hervé; Ricci, Stefano

    2015-05-01

    Although severely affected by the angle dependency, carotid artery peak systolic velocity measurements are widely used for assessment of stenosis. In this study, blood peak systolic velocities in the common and internal carotid arteries of both healthy volunteers and patients with internal carotid artery stenosis were measured by two vector Doppler (VD) methods and compared with measurements obtained with the conventional spectral Doppler approach. Although the two VD techniques were completely different (using the transmission of focused beams and plane waves, respectively), the measurement results indicate that these techniques are nearly equivalent. The peak systolic velocities measured in 22 healthy common carotid arteries by the two VD techniques were very close (according to Bland-Altman analysis, the average difference was 3.2%, with limits of agreement of ± 8.6%). Application of Bland-Altman analysis to comparison of either VD technique with the spectral Doppler method provided a 21%-25% average difference with ± 13%-15% limits of agreement. Analysis of the results obtained from 15 internal carotid arteries led to similar conclusions, indicating significant overestimation of peak systolic velocity with the spectral Doppler method. Inter- and intra-operator repeatability measurements performed in a group of 8 healthy volunteers provided equivalent results for all of the methods (coefficients of variability in the range 2.7%-6.9%), even though the sonographers were not familiar with the VD methods. The results of this study suggest that the introduction of vector Doppler methods in commercial machines may finally be considered mature and capable of overcoming the angle-dependent overestimation typical of the standard spectral Doppler approach.

  14. 3-D Ultrasound Guidance of Autonomous Robot for Location of Ferrous Shrapnel

    PubMed Central

    Rogers, Albert J.; Light, Edward D.

    2010-01-01

    Vibrations can be induced in ferromagnetic shrapnel by a variable electromagnet. Real time 3-D color Doppler ultrasound located the induced motion in a needle fragment and determined its 3-D position in the scanner coordinates. This information was used to guide a robot which moved a probe to touch the shrapnel fragment. PMID:19574140

  15. 3-D ultrasound guidance of autonomous robot for location of ferrous shrapnel.

    PubMed

    Rogers, Albert J; Light, Edward D; Smith, Stephen W

    2009-07-01

    Vibrations can be induced in ferromagnetic shrapnel by a variable electromagnet. Real time 3-D color Doppler ultrasound located the induced motion in a needle fragment and determined its 3-D position in the scanner coordinates. This information was used to guide a robot which moved a probe to touch the shrapnel fragment.

  16. Three-dimensional ultrasound imaging of the vasculature.

    PubMed

    Fenster, A; Lee, D; Sherebrin, S; Rankin, R; Downey, D

    1998-02-01

    With conventional ultrasonography, the diagnostician must view a series of two-dimensional images in order to form a mental impression of the three-dimensional anatomy, an efficient and time consuming practice prone to operator variability, which may cause variable or even incorrect diagnoses. Also, a conventional two-dimensional ultrasound image represents a thin slice of the patients anatomy at a single location and orientation, which is difficult to reproduce at a later time. These factors make conventional ultrasonography non-optimal for prospective or follow-up studies. Our efforts have focused on overcoming these deficiencies by developing three-dimensional ultrasound imaging techniques that are capable of acquiring B-mode, colour Doppler and power Doppler images of the vasculature, by using a conventional ultrasound system to acquire a series of two-dimensional images and then mathematically reconstructing them into a single three-dimensional image, which may then be viewed interactively on an inexpensive desktop computer. We report here on two approaches: (1) free-hand scanning, in which a magnetic positioning device is attached to the ultrasound transducer to record the position and orientation of each two-dimensional image needed for the three-dimensional image reconstruction; and (2) mechanical scanning, in which a motor-driven assembly is used to translate the transducer linearly across the neck, yielding a set of uniformly-spaced parallel two-dimensional images.

  17. Coherent Flow Power Doppler (CFPD): Flow Detection using Spatial Coherence Beamforming

    PubMed Central

    Li, You Leo; Dahl, Jeremy J.

    2015-01-01

    Power Doppler imaging is a widely used method of flow detection for tissue perfusion monitoring, inflammatory hyperemia detection, deep vein thrombosis diagnosis, and other clinical applications. However, thermal noise and clutter limit its sensitivity and ability to detect slow flow. In addition, large ensembles are required to obtain sufficient sensitivity, which limits frame rate and yields flash artifacts during moderate tissue motion. We propose an alternative method of flow detection using the spatial coherence of backscattered ultrasound echoes. The method enhances slow flow detection and frame rate, while maintaining or improving the signal quality of conventional power Doppler techniques. The feasibility of this method is demonstrated with simulations, flow-phantom experiments, and an in-vivo human thyroid study. In comparison to conventional power Doppler imaging, the proposed method can produce Doppler images with 15-30 dB SNR improvement. Therefore, it is able to detect flow with velocities approximately 50% lower than conventional power Doppler, or improve the frame rate by a factor of 3 with comparable image quality. The results show promise for clinical applications of the method. PMID:26067037

  18. [Color-coded M-mode Doppler echocardiography in the diagnosis of fetal arrhythmia].

    PubMed

    Gembruch, U; Bald, R; Hansmann, M

    1990-04-01

    Colour-coded M-mode Doppler echocardiography is a simultaneous registration of the conventional M-mode echocardiogram and of the pulsed wave colour-coded Doppler echocardiogram with simultaneous analysis of several sample volumes along the ultrasound cursor with a high timely resolution, guided by the two-dimensional imaging. Within 9 months, 36 foetuses with arrhythmias were prospectively examined (24 foetuses with atrial premature beats, 9 foetuses with supraventricular tachycardia, and 3 foetuses with complete heart block). The classification of arrhythmia by the colour-coded M-mode Doppler echocardiography was always possible at first examination. The most important advantage of this method is the simultaneous registration of the information of conventional M-mode and Doppler echocardiography. Therefore, the intervals between atrial and ventricular contractions can also be analysed even when the angle of insonation to the foetal heart is unfavourable, since contractions cannot only be identified by wall movements but also by the flow velocities. Furthermore, the duration of regurgitation of atrioventricular valves can be exactly measured by colour-coded M-mode Doppler echocardiography. In foetal supraventricular tachycardia, it appears that severity of congestive heart failure is correlated with the duration of atrioventricular valve regurgitation up to a holosystolic insufficiency. Thus, it seems possible, that the duration of insufficiency of atrioventricular valves is a good parameter for evaluation of cardiac function and for modifying antiarrhythmic treatment in cases of supraventricular tachycardia.

  19. Applications of Fresnel-Kirchhoff diffraction theory in the analysis of human-motion Doppler sonar grams.

    PubMed

    Bradley, Marshall; Sabatier, James M

    2010-11-01

    Observed human-gait features in Doppler sonar grams are explained by using the Boulic-Thalmann (BT) model to predict joint angle time histories and the temporal displacements of the body center of mass. Body segments are represented as ellipsoids. Temporally dependent velocities at the proximal and distal end of key body segments are determined from BT. Doppler sonar grams are computed by mapping velocity-time dependent spectral acoustic-cross sections for the body segments onto time-velocity space, mimicking the Short Time Fourier Transform used in the Doppler sonar processing. Comparisons to measured data indicate that dominant returns come from trunk, thigh and lower leg.

  20. A symposium on obstetrical ultrasound: is all this safe for the fetus?

    PubMed

    Sheiner, Eyal; Abramowicz, Jacques S

    2012-03-01

    Diagnostic ultrasound is a form of energy that has the potential for effects in tissues (bioeffects). The 2 most likely mechanisms are heating and cavitation. The thermal index (TI) expresses the potential for rise in temperature. The MI indicates the potential for the ultrasound to induce inertial cavitation. Scarce data exist regarding instrument's acoustic output for routine ultrasound examinations. Data collected during routine ultrasound examinations (first trimester for viability, nuchal translucency, anatomy surveys including 3-dimensional/4-dimensional studies and growth studies) show that "gray-scale" B-mode ultrasound is associated with a negligible rise in TI. However, Doppler studies show significantly higher levels of TI, which can reach 1.5 and above.

  1. Right Ventricular Tissue Doppler in Space Flight

    NASA Technical Reports Server (NTRS)

    Hamilton, Douglas R.; Barratt, Michael R.; Sargsyan, Ashot E.; Ebert, Douglas; Garcia, Kathleen M.; Martin, David S.; Dulchavsky, Scott A.; Duncan, J. Michael

    2009-01-01

    Tissue Doppler (TD) registers movement of a given sample of cardiac tissue throughout the cardiac cycle. TD spectra of the right ventricle (RV) were obtained from a long-duration ISS crewmember as a portion of an ongoing experiment ("Braslet" test objective). To our knowledge, this is the first report of RV TD conducted in space flight, and the data represent reproducibility and fidelity of this application in space and serve as the first "space normal" data set. Methods RV TD was performed by astronaut scientists remotely guided by an ultrasound expert from Mission Control Center, Houston, TX. In four of the subjects, RV TD was acquired from the free wall near the tricuspid annulus in two separate sessions 4 to 7 days apart. A fifth subject had only one session. All digital DICOM frames were exported for off-line analysis. Systolic (S ), early diastolic (E ) and late diastolic (A ) velocities were measured. RV Tei-index was calculated using diastolic and systolic time intervals as a combined measure of myocardial performance. Results and Discussion The mean values from the first 4 subjects (8 sessions) were used as the on-orbit reference data, and subject 5 was considered as a hypothetical patient for comparison (see Table). The greatest difference was in the early diastolic A (31 %) yet the standard deviation (a) for A amongst the reference subjects was 2.25 (mean = 16.02). Of interest is the Tei index, a simple and feasible indicator of overall ventricular function; it was similar amongst all the subjects. The late diastolic A seems to compensate for the variance in E . Normal Tei index for the RV is < 0.3, yet our data show all but one subject consistently above this level, notwithstanding their nominal responses to daily exercise in microgravity. These data remind us that the physiology of RV preload in altered gravity environments is still not completely understood.

  2. Turbulent transport measurements with a laser Doppler velocimeter

    NASA Technical Reports Server (NTRS)

    Edwards, R. V.; Angus, J. C.; Dunning, J. W., Jr.

    1972-01-01

    The power spectrum of phototube current from a laser Doppler velocimeter operating in the heterodyne mode has been computed. The spectrum is obtained in terms of the space time correlation function of the fluid. The spectral width and shape predicted by the theory are in agreement with experiment. For normal operating parameters the time average spectrum contains information only for times shorter than the Lagrangian integral time scale of the turbulence. To examine the long time behavior, one must use either extremely small scattering angles, much longer wavelength radiation or a different mode of signal analysis, e.g., FM detection.

  3. Review of Quantitative Ultrasound: Envelope Statistics and Backscatter Coefficient Imaging and Contributions to Diagnostic Ultrasound.

    PubMed

    Oelze, Michael L; Mamou, Jonathan

    2016-02-01

    Conventional medical imaging technologies, including ultrasound, have continued to improve over the years. For example, in oncology, medical imaging is characterized by high sensitivity, i.e., the ability to detect anomalous tissue features, but the ability to classify these tissue features from images often lacks specificity. As a result, a large number of biopsies of tissues with suspicious image findings are performed each year with a vast majority of these biopsies resulting in a negative finding. To improve specificity of cancer imaging, quantitative imaging techniques can play an important role. Conventional ultrasound B-mode imaging is mainly qualitative in nature. However, quantitative ultrasound (QUS) imaging can provide specific numbers related to tissue features that can increase the specificity of image findings leading to improvements in diagnostic ultrasound. QUS imaging can encompass a wide variety of techniques including spectral-based parameterization, elastography, shear wave imaging, flow estimation, and envelope statistics. Currently, spectral-based parameterization and envelope statistics are not available on most conventional clinical ultrasound machines. However, in recent years, QUS techniques involving spectral-based parameterization and envelope statistics have demonstrated success in many applications, providing additional diagnostic capabilities. Spectral-based techniques include the estimation of the backscatter coefficient (BSC), estimation of attenuation, and estimation of scatterer properties such as the correlation length associated with an effective scatterer diameter (ESD) and the effective acoustic concentration (EAC) of scatterers. Envelope statistics include the estimation of the number density of scatterers and quantification of coherent to incoherent signals produced from the tissue. Challenges for clinical application include correctly accounting for attenuation effects and transmission losses and implementation of QUS on

  4. Two-dimensional intraventricular flow mapping by digital processing conventional color-Doppler echocardiography images.

    PubMed

    Garcia, Damien; Del Alamo, Juan C; Tanne, David; Yotti, Raquel; Cortina, Cristina; Bertrand, Eric; Antoranz, José Carlos; Perez-David, Esther; Rieu, Régis; Fernandez-Aviles, Francisco; Bermejo, Javier

    2010-10-01

    Doppler echocardiography remains the most extended clinical modality for the evaluation of left ventricular (LV) function. Current Doppler ultrasound methods, however, are limited to the representation of a single flow velocity component. We thus developed a novel technique to construct 2D time-resolved (2D+t) LV velocity fields from conventional transthoracic clinical acquisitions. Combining color-Doppler velocities with LV wall positions, the cross-beam blood velocities were calculated using the continuity equation under a planar flow assumption. To validate the algorithm, 2D Doppler flow mapping and laser particle image velocimetry (PIV) measurements were carried out in an atrio-ventricular duplicator. Phase-contrast magnetic resonance (MR) acquisitions were used to measure in vivo the error due to the 2D flow assumption and to potential scan-plane misalignment. Finally, the applicability of the Doppler technique was tested in the clinical setting. In vitro experiments demonstrated that the new method yields an accurate quantitative description of the main vortex that forms during the cardiac cycle (mean error for vortex radius, position and circulation). MR image analysis evidenced that the error due to the planar flow assumption is close to 15% and does not preclude the characterization of major vortex properties neither in the normal nor in the dilated LV. These results are yet to be confirmed by a head-to-head clinical validation study. Clinical Doppler studies showed that the method is readily applicable and that a single large anterograde vortex develops in the healthy ventricle while supplementary retrograde swirling structures may appear in the diseased heart. The proposed echocardiographic method based on the continuity equation is fast, clinically-compliant and does not require complex training. This technique will potentially enable investigators to study of additional quantitative aspects of intraventricular flow dynamics in the clinical setting by

  5. Embedded Doppler system for industrial in-line rheometry.

    PubMed

    Ricci, Stefano; Liard, Maxime; Birkhofer, Beat; Lootens, Didier; Bruhwiler, Armin; Tortoli, Piero

    2012-07-01

    Rheological fluid behavior characterization is crucial for the industrial production of cosmetics, food, pharmaceutics, adhesive, sealants, etc. For example, the measurement of specific rheological features at every step of the production chain is critical for product quality control. Such measurements are often limited to laboratory tests on product specimens because of technical difficulties. In this work, we present an embedded system suitable for in-line rheometric evaluation of highly filled polyurethane-based adhesives. This system includes an ultrasound front-end and a digital signal processing section integrated in a low-cost field-programmable gate array. The system measures the real-time velocity profile developed in the pipe by the fluid, employing a Doppler multigate technique. The high-resolution velocity profile, combined with a pressure drop measurement, allows an accurate evaluation of the flow consistency index, K, and the flow behavior index, n, of the interrogated fluid.

  6. Data acquisition system for harmonic motion microwave Doppler imaging.

    PubMed

    Tafreshi, Azadeh Kamali; Karadaş, Mürsel; Top, Can Barış; Gençer, Nevzat Güneri

    2014-01-01

    Harmonic Motion Microwave Doppler Imaging (HMMDI) is a hybrid method proposed for breast tumor detection, which images the coupled dielectric and elastic properties of the tissue. In this paper, the performance of a data acquisition system for HMMDI method is evaluated on breast phantom materials. A breast fat phantom including fibro-glandular and tumor phantom regions is produced. The phantom is excited using a focused ultrasound probe and a microwave transmitter. The received microwave signal level is measured on three different points inside the phantom (fat, fibro-glandular, and tumor regions). The experimental results using the designed homodyne receiver proved the effectiveness of the proposed setup. In tumor phantom region, the signal level decreased about 3 dB compared to the signal level obtained from the fibro-glandular phantom area, whereas this signal was about 4 dB higher than the received signal from the fat phantom.

  7. Vascular flow and perfusion imaging with ultrasound contrast agents.

    PubMed

    Bruce, Matthew; Averkiou, Mike; Tiemann, Klaus; Lohmaier, Stefan; Powers, Jeff; Beach, Kirk

    2004-06-01

    Current techniques for imaging ultrasound (US) contrast agents (UCA) make no distinction between low-velocity microbubbles in the microcirculation and higher-velocity microbubbles in the larger vasculature. A combination of radiofrequency (RF) and Doppler filtering on a low mechanical index (MI) pulse inversion acquisition is presented that differentiates low-velocity microbubbles (on the order of mm/s) associated with perfusion, from the higher-velocity microbubbles (on the order of cm/s) in larger vessels. In vitro experiments demonstrate the ability to separate vascular flow using both harmonic and fundamental Doppler signals. Fundamental and harmonic Doppler signals from microbubbles using a low-MI pulse-inversion acquisition are compared with conventional color Doppler signals in vivo. Due to the lower transmit amplitude and enhanced backscatter from microbubbles, the in vivo signal to clutter ratios for both the fundamental (-11 dB) and harmonic (-4 dB) vascular flow signals were greater than with conventional power Doppler (-51 dB) without contrast agent. The processing investigated here, in parallel with conventional pulse-inversion processing, enables the simultaneous display of both perfusion and vascular flow. In vivo results demonstrating the feasibility and potential utility of the real-time display of both perfusion and vascular flow using US contrast agents are presented and discussed.

  8. Carotid arterial blood pressure waveform monitoring using a portable ultrasound system.

    PubMed

    Joohyun Seo; Pietrangelo, Sabino J; Hae-Seung Lee; Sodini, Charles G

    2015-08-01

    This work presents a non-invasive arterial blood pressure (ABP) waveform monitoring technique using ultrasound. A portable ultrasound system to excite ultrasound transducers and acquire data is designed with off-the-shelf components. The insonation angles are identified using a vector Doppler technique based on the cosine dependency of the Doppler signals. The pulse pressure of an estimated waveform at the left common carotid artery is compared to the standard sphygmomanometer measurement in a clinical test. The estimated carotid ABP waveform shows excellent agreement to the finger ABP waveform with expected discrepancy of the systolic peak shape due to different measurement sites. The proposed method also tracks slow blood pressure fluctuations. This validation on human subjects shows potential for a noninvasive blood pressure waveform monitoring device at central arterial sites.

  9. Trace analysis of rubidium hyperfine structure in a flame atomizer using sub-Doppler laser wave-mixing spectroscopy.

    PubMed

    Weed, Kenneth M; Tong, William G

    2003-12-01

    Nonlinear laser wave mixing is a versatile spectroscopic method for trace elemental analysis at high spectral resolution. Sub-Doppler spectral resolution allows isotope and hyperfine structure measurements of some of the elements even when using a room-pressure analytical flame (i.e., sub-Doppler but Lorentzian broadened spectra). A non-planar wave-mixing optical setup offers some advantages as compared to the conventional planar wave-mixing setup including better signal collection efficiency and easier optical alignment. Using our absorption-based wave mixing, a detection limit of 0.05 ng/mL (i.e., 50 parts-per-trillion) is reported for Rb in an air/acetylene flame, while still maintaining sub-Doppler spectral resolution for the infrared 780.0-nm Rb transition line.

  10. Bubble-induced Color Doppler Feedback for Histotripsy Tissue Fractionation

    PubMed Central

    Miller, Ryan M.; Zhang, Xi; Maxwell, Adam; Cain, Charles; Xu, Zhen

    2016-01-01

    Histotripsy therapy produces cavitating bubble clouds to increasingly fractionate and eventually liquefy tissue using high intensity ultrasound pulses. Following cavitation generated by each pulse, coherent motion of the cavitation residual nuclei can be detected using metrics formed from ultrasound color Doppler acquisitions. In this paper, three experiments were performed to investigate the characteristics of this motion as real-time feedback on histotripsy tissue fractionation. In the first experiment, bubble-induced color Doppler (BCD) and particle image velocimetry (PIV) analysis monitored the residual cavitation nuclei in the treatment region in an agarose tissue phantom treated with 2-cycle histotripsy pulses at > 30 MPa using a 500 kHz transducer. Both BCD and PIV results showed brief chaotic motion of the residual nuclei followed by coherent motion first moving away from the transducer and then rebounding back. Velocity measurements from both PIV and BCD agreed well, showing a monotonic increase in rebound time up to a saturation point for increased therapy dose. In a second experiment, a thin layer of red blood cells (RBC) was added to the phantom to allow quantification of the fractionation of the RBC layer to compare with BCD metrics. A strong linear correlation was observed between the fractionation level and the time to BCD peak rebound velocity over histotripsy treatment. Finally, the correlation between BCD feedback and histotripsy tissue fractionation was validated in ex vivo porcine liver evaluated histologically. BCD metrics showed strong linear correlation with fractionation progression, suggesting that BCD provides useful quantitative real-time feedback on histotripsy treatment progression. PMID:26863659

  11. Comparison of foetomaternal circulation in normal pregnancies and pregnancy induced hypertension using color Doppler studies.

    PubMed

    Gupta, Shikha; Misra, R; Ghosh, U K; Gupta, V; Srivastava, D

    2014-01-01

    The aim of present study was to assess fetomaternal blood flows in normal and abnormal pregnancies using color Doppler indices. Subjects were divided into two groups as: Group A of 25 subjects of normal pregnancy as controls and group B of 25 subjects of pregnancy induced hypertension. All the subjects were lying in the age-group of 25-35 years and having 28 to 34 weeks of gestation; the patients were evaluated by detailed history and were subjected to complete general examination. Blood pressure was taken on two occasions at least 6 hours apart. Systemic examination and obstetrical examination was done in all subjects. All cases were subjected to pathological tests- Haemogram, Test for proteins in urine. Ultrasound assessment of fetal growth was done by measuring BPD (Biparietal diameter), HC (Head circumference), FL (Femur length) and AC (Abdominal circumference): Average gestational age and effective fetal weight was then calculated by ultrasound machine. Color Doppler was used to assess the various Doppler indices indices: Pulsatility index (PI), Resistive index (RI) and Systolic diastolic ratio (S/D ratio) in bilateral uterine, umbilical and middle cerebral arteries and compared to the standard normograms. Percentage of subjects having abnormal Doppler indices were calculated. Assessment of percentage of SGA (small for gestational age) fetuses was done in all the three groups. Decline in mean values of all Doppler indices was found with advancing gestational age in normal pregnancy suggesting decreased vascular resistance and increased blood flow in fetomaternal circulation. In pregnancy induced hypertensives, the mean values of Doppler indices showed a decline as in normal pregnancy but showed an increase (more than 2 S.D. of the mean) for that gestational age in comparison to the control group suggesting increased impedance to blood flow in uteroplacental and fetomaternal circulation. Umbilical artery Doppler indices were found to be the most sensitive

  12. Active Region Moss: Doppler Shifts from Hinode/EIS Observations

    NASA Technical Reports Server (NTRS)

    Tripathi, Durgesh; Mason, Helen E.; Klimchuk, James A.

    2012-01-01

    Studying the Doppler shifts and the temperature dependence of Doppler shifts in moss regions can help us understand the heating processes in the core of the active regions. In this paper we have used an active region observation recorded by the Extreme-ultraviolet Imaging Spectrometer (EIS) onboard Hinode on 12-Dec- 2007 to measure the Doppler shifts in the moss regions. We have distinguished the moss regions from the rest of the active region by defining a low density cut-off as derived by Tripathi et al. (2010). We have carried out a very careful analysis of the EIS wavelength calibration based on the method described in Young, O Dwyer and Mason (2012). For spectral lines having maximum sensitivity between log T = 5.85 and log T = 6.25 K, we find that the velocity distribution peaks at around 0 km/s with an estimated error of 4 km/s. The width of the distribution decreases with temperature. The mean of the distribution shows a blue shift which increases with increasing temperature and the distribution also shows asymmetries towards blue-shift. Comparing these results with observables predicted from different coronal heating models, we find that these results are consistent with both steady and impulsive heating scenarios. Further observational constraints are needed to distinguish between these two heating scenarios.

  13. Zeeman Doppler Maps: Always Unique, Never Spurious?

    NASA Astrophysics Data System (ADS)

    Stift, Martin J.; Leone, Francesco

    2017-01-01

    Numerical models of atomic diffusion in magnetic atmospheres of ApBp stars predict abundance structures that differ from the empirical maps derived with (Zeeman) Doppler mapping (ZDM). An in-depth analysis of this apparent disagreement investigates the detectability by means of ZDM of a variety of abundance structures, including (warped) rings predicted by theory, but also complex spot-like structures. Even when spectra of high signal-to-noise ratio are available, it can prove difficult or altogether impossible to correctly recover shapes, positions, and abundances of a mere handful of spots, notwithstanding the use of all four Stokes parameters and an exactly known field geometry; the recovery of (warped) rings can be equally challenging. Inversions of complex abundance maps that are based on just one or two spectral lines usually permit multiple solutions. It turns out that it can by no means be guaranteed that any of the regularization functions in general use for ZDM (maximum entropy or Tikhonov) will lead to a true abundance map instead of some spurious one. Attention is drawn to the need for a study that would elucidate the relation between the stratified, field-dependent abundance structures predicted by diffusion theory on the one hand, and empirical maps obtained by means of “canonical” ZDM, i.e., with mean atmospheres and unstratified abundances, on the other hand. Finally, we point out difficulties arising from the three-dimensional nature of the atomic diffusion process in magnetic ApBp star atmospheres.

  14. Evaluation of factors influencing arterial Doppler waveforms in an in vitro flow phantom

    PubMed Central

    2017-01-01

    Purpose The aim of this study was to investigate factors that influence arterial Doppler waveforms in an in vitro phantom to provide a more accurate and comprehensive explanation of the Doppler signal. Methods A flow model was created using a pulsatile artificial heart, rubber or polyethylene tubes, a water tank, and a glass tube. Spectral Doppler tracings were obtained in multiple combinations of compliance, resistance, and pulse rate. Peak systolic velocity, minimum diastolic velocity, resistive index (RI), pulsatility index, early systolic acceleration time, and acceleration index were measured. On the basis of these measurements, the influences of the variables on the Doppler waveforms were analyzed. Results With increasing distal resistance, the RI increased in a relatively linear relationship. With increasing proximal resistance, the RI decreased. The pulsus tardus and parvus phenomenon was observed with a small acceleration index in the model with a higher grade of stenosis. An increase in the distal resistance masked the pulsus tardus and parvus phenomenon by increasing the acceleration index. Although this phenomenon occurred independently of compliance, changes in the compliance of proximal or distal tubes caused significant changes in the Doppler waveform. There was a reverse relationship between the RI and the pulse rate. Conclusion Resistance and compliance can alter the Doppler waveforms independently. The pulse rate is an extrinsic factor that also influences the RI. The compliance and distal resistance, as well as proximal resistance, influence the pulsus tardus and parvus phenomenon. PMID:27784154

  15. The influence of laser spot size on the micro-Doppler spectrum

    NASA Astrophysics Data System (ADS)

    Zhang, Dehua; Zhang, Haiyang; Zheng, Zheng; Yang, Hongzhi; Zhao, Changming; Yang, Suhui

    2015-08-01

    Micro-Doppler effect, which is induced by micro motion of target or any structure on the target, is a frequency modulation that generates sidebands about the target's Doppler frequency shift, such as mechanical vibration or rotation. When a target's motions incorporate micro motions, the radar echo signal will contain micro-Doppler characteristics related to these motions. Therefore, the micro-Doppler effect provides a new approach to obtain the dynamic properties of targets, which can be used to accomplish the detection and identification of targets, such as the identification of different types of helicopters. Scattering of the laser spot from a target surface modulates the Doppler signal, causes broadening of the signal spectrum, and, adds uncertainty to the signature analysis. A mathematic model of cone spin, which is a typical micro motion, is built first in this paper. Furthermore, an analyzed equation is deduced to predict the micro-Doppler spectral broadening of acquired medium current signals in situations of different laser spot size. It is found that the beam spot size on the target affects the resulting spectral broadening. Finally, an experiment based on the scaled model is performed to verify the simulation. A narrow-linewidth single frequency fiber laser is employed to detect the cone target at different laser spot size by coherent detection with constant detect distance and laser power. The experimental result shows that the beam spot size on the target affects the resulting spectral broadening caused by speckle, which corresponds to the simulation result. The experimental broadening was consistently greater than the theoretical broadening due to other effects that also contribute to the total broadening.

  16. [Ultrasound in pediatric dermatology].

    PubMed

    García-Martínez, F J; Muñoz-Garza, F Z; Hernández-Martín, A

    2015-11-01

    Cutaneous ultrasound is particularly useful in pediatric dermatology to diagnose numerous diseases without the need to use invasive tests. The present articles reviews some frequent dermatological entities in children whose study can be simplified through cutaneous ultrasound. This article also provides practical recommendations reported in the literature that may facilitate ultrasound examination, with special mention of benign tumoural disease, both congenital and acquired, and vascular anomalies.

  17. Children's (Pediatric) Abdominal Ultrasound Imaging

    MedlinePlus

    ... waves. Ultrasound imaging, also called ultrasound scanning or sonography , involves the use of a small transducer (probe) and ultrasound gel placed directly on the skin. High-frequency sound waves are transmitted from the ...

  18. Ultrasound of the Thyroid Gland

    MedlinePlus

    ... waves. Ultrasound imaging, also called ultrasound scanning or sonography , involves the use of a small transducer (probe) and ultrasound gel placed directly on the skin. High-frequency sound waves are transmitted from the ...

  19. Velocity magnitude estimation with linear arrays using Doppler bandwidth.

    PubMed

    Tortoli, P; Guidi, G; Mantovani, L; Newhouse, V L

    2001-04-01

    The dependence of pulsed wave Doppler bandwidth on parameters typical of linear transducer arrays used in commercial Duplex and color flow mapping systems is investigated experimentally. For a single flow line it is observed that this bandwidth generally depends not only on the scatterer velocity and the beam-to-flow angle, but also on the flow line range and orientation. This is due to the fact that in Duplex and color flow systems the transducer is differently focused in the scan and elevation planes and its aperture and focal lengths are often made to vary, depending on the distance of the flow line from the transducer. It is however experimentally demonstrated that, at points where the ultrasound beamwidths in the scan and elevation planes are both comparable to the sample volume length, the Doppler bandwidth is independent of the beam-to-flow angle. It is also shown that this invariance can be extended to other ranges by appropriately modifying the array aperture. Finally, as an application of this independence, the flow-line velocity magnitude in these beam regions is estimated with better than 5% uncertainty through a simple bandwidth measurement.

  20. Detection of Doppler Microembolic Signals Using High Order Statistics

    PubMed Central

    Geryes, Maroun; Hassan, Walid; Mcheick, Ali

    2016-01-01

    Robust detection of the smallest circulating cerebral microemboli is an efficient way of preventing strokes, which is second cause of mortality worldwide. Transcranial Doppler ultrasound is widely considered the most convenient system for the detection of microemboli. The most common standard detection is achieved through the Doppler energy signal and depends on an empirically set constant threshold. On the other hand, in the past few years, higher order statistics have been an extensive field of research as they represent descriptive statistics that can be used to detect signal outliers. In this study, we propose new types of microembolic detectors based on the windowed calculation of the third moment skewness and fourth moment kurtosis of the energy signal. During energy embolus-free periods the distribution of the energy is not altered and the skewness and kurtosis signals do not exhibit any peak values. In the presence of emboli, the energy distribution is distorted and the skewness and kurtosis signals exhibit peaks, corresponding to the latter emboli. Applied on real signals, the detection of microemboli through the skewness and kurtosis signals outperformed the detection through standard methods. The sensitivities and specificities reached 78% and 91% and 80% and 90% for the skewness and kurtosis detectors, respectively. PMID:28096889

  1. Intravascular ultrasound imaging

    SciTech Connect

    Cavaye, D.M.; White, R.A. )

    1992-01-01

    This book will give vascular surgeons, cardiologists, radiologists, and technologists a complete working knowledge of intravascular ultrasound imaging and the crucial role of this new technology in endovascular diagnosis and therapy. The book reviews the essential principles of vascular pathology and ultrasound imaging and then provides state-of-the-art information on intraluminal ultrasound imaging devices and techniques, including practical guidelines for using catheters, optimizing image quality, and avoiding artifacts. Image interpretation and computerized image reconstruction are also discussed in detail. The first section explains the diagnostic, therapeutic, and experimental applications of intravascular ultrasound, particularly as a adjunct to angioplasty and other current interventional procedures.

  2. Pipe flow measurements of turbulence and ambiguity using laser-Doppler velocimetry

    NASA Technical Reports Server (NTRS)

    Berman, N. S.; Dunning, J. W.

    1973-01-01

    The laser-Doppler ambiguities predicted by George and Lumley (1973) have been verified experimentally for turbulent pipe flows. Experiments were performed at Reynolds numbers from 5000 to 15,000 at the center line and near the wall. Ambiguity levels were measured from power spectral densities of FM demodulated laser signals and were compared with calculations based on the theory. The turbulent spectra for these water flows after accounting for the ambiguity were equivalent to hot-film measurements at similar Reynolds numbers. The feasibility of laser-Doppler measurements very close to the wall in shear flows is demonstrated.

  3. Rayleigh-backscattering doppler broadening correction for differential absorption lidar

    NASA Astrophysics Data System (ADS)

    Fan, Lanlan; Zhang, Yinchao; Chen, Siying; Guo, Pan; Chen, He

    2015-11-01

    The spectral broadening by Rayleigh backscattering can cause large changes in water vapor echo signals, causing errors when the water vapor concentration is inversed by differential absorption lidar (DIAL). A correction algorithm is proposed to revise the errors due to the effect of laser spectral broadening. The relative errors of water vapor are calculated in cases of different aerosol distribution and temperature changes before and after correction. The results show that measurement errors due to the Doppler broadening are more than 5% before correction and a 2% measurement error after corrected for the case of a smooth, background aerosol distribution. However, due to the high aerosol gradients and strong temperature inversion, errors can be up to 40% and 10% with no corrections for this effect, respectively. The relative errors can reduce to less than 2% after correction. Hence, the correction algorithm for Rayleigh Doppler broadening can improve detection accuracy in H2O DIAL measurements especially when it is applied to high aerosol concentration or strong temperature inversion.

  4. Performance Of A Doppler-Corrected MDPSK Detector

    NASA Technical Reports Server (NTRS)

    Nguyen, Tien M.; Jedrey, Thomas C.; Hinedi, Sami; Agan, Martin J.

    1994-01-01

    Report presents theoretical analysis of effect of rate of change of Doppler shift of received multiple-differential-phase-shift-keyed (MDPSK) radio signal on performance of Doppler-corrected differential detector. In particular detector, phase of received signal corrected for Doppler shift by use of Doppler estimator designed to operate in presence of negligibly small Doppler rate.

  5. Equations for Bistatic Doppler Shift and Rate of Change of Doppler Shift of Dark Satellite Observations

    DTIC Science & Technology

    Equations are given for the doppler shift and rate of change of doppler shift for the bistatic case where an orbiting, nontransmitting earth... of change of doppler shift, satellite height, earth-center angle between the receiver and the satellite, and zenith angle from receiver to satellite are shown for a typical satellite, 1958 Alpha, Explorer I....have been computed, using transmitting and receiving sites of the Space Surveillance System. Plots of various relationships between doppler shift, rate

  6. [Ultrasonic quantification, value of color and contribution of transcranial Doppler sonography in carotid artery surgery].

    PubMed

    Berni, A; Cavaiola, S; Mele, R; Tombesi, T; Custureri, F; D'Andrea, V; Marchesi, M; Tromba, L

    1996-05-01

    The authors briefly report their experience regarding the opportunities offered by the use of current ultrasound methods in carotid surgery. They describe: a system for the quantification of athcromasic plaque used to monitor non-operated patients over time; ultrasound methods used to analyse the carotid wall to establish whether it can be utilised as an index of vascular aggression in hypertension, diabetes and atherosclerosis; the use of transcranial Doppler; criteria for the definition of high risk plaque; the applications of eco-color Doppler. The paper also illustrates a new pathology identified by the authors, defined as primary intimal fibrous hyperplasia, and the evolution of the carotid wall after endarterectomy. The structural characteristics of primary hyperplasia can only be shown using ultrasound given that arteriography cannot distinguish it from atheromatic stenosis. After endarterectomy the carotid wall is subject to hematic and hemodynamic stimuli which determine the type of evolution of the wall itself. The authors therefore examine the myointimal reaction, myointimal hyperplasia, early restenosis and late restenosis as different facets of the same phenomenon.

  7. Dynamic multiplanar real time ultrasound guided infraclavicular subclavian vein catheterization.

    PubMed

    Zhong, Xin; Hamill, Mark; Collier, Bryan; Bradburn, Eric; Ferrara, John

    2015-06-01

    Ultrasound guided vascular access has been well-characterized as a safe and effective technique for internal jugular and femoral vein catheterization. However, there is limited experience with the use of ultrasound to access the infraclavicular subclavian vein. Multiple ultrasound techniques do exist to identify the subclavian vein, but real time access is limited by vessel identification in a single planar view. To overcome this limitation, a novel technique of ultrasound guided infraclavicular subclavian vein catheterization using a real time multiplanar approach has been developed. The initial experience with this approach is described. A single surgeon used combined oblique, transverse, and longitudinal views along with Doppler color flow images to both define the infraclavicular anatomy and to obtain subclavian vein access in 42 adult patients (20 M/22 F and 22 L/20 R) with a mean body mass index of 29.2 (range = 18.9-55.4). Chest x-ray was obtained to confirm position and to rule out pneumothorax. Subclavian vein cannulation was achieved in 100 per cent of patients; subsequent catheterization was successful in 92.9 per cent. The number of attempts required for cannulation averaged 1.3 (range = 1-5), and decreased after a five patient learning curve. No patient developed a pneumothorax, hematoma, or cannula malposition. Ultrasound guided multiplanar infraclavicular subclavian vein access appears to be a safe and effective adjunct for central line placement.

  8. Ultrasound skin imaging.

    PubMed

    Alfageme Roldán, F

    2014-12-01

    The interaction of high-frequency ultrasound waves with the skin provides the basis for noninvasive, fast, and accessible diagnostic imaging. This tool is increasingly used in skin cancer and inflammatory conditions as well as in cosmetic dermatology. This article reviews the basic principles of skin ultrasound and its applications in the different areas of dermatology.

  9. Pelvic ultrasound - abdominal

    MedlinePlus

    ... pelvic ultrasound. In: Lumb P, Karakitsos D, eds. Critical Care Ultrasound. Philadelphia, PA: Elsevier Saunders; 2015:chap 43. Review Date 3/4/2016 Updated by: Irina Burd, MD, PhD, Associate Professor of Gynecology and Obstetrics at Johns Hopkins University School of Medicine, Baltimore, ...

  10. Spectral Predictors

    SciTech Connect

    Ibarria, L; Lindstrom, P; Rossignac, J

    2006-11-17

    Many scientific, imaging, and geospatial applications produce large high-precision scalar fields sampled on a regular grid. Lossless compression of such data is commonly done using predictive coding, in which weighted combinations of previously coded samples known to both encoder and decoder are used to predict subsequent nearby samples. In hierarchical, incremental, or selective transmission, the spatial pattern of the known neighbors is often irregular and varies from one sample to the next, which precludes prediction based on a single stencil and fixed set of weights. To handle such situations and make the best use of available neighboring samples, we propose a local spectral predictor that offers optimal prediction by tailoring the weights to each configuration of known nearby samples. These weights may be precomputed and stored in a small lookup table. We show that predictive coding using our spectral predictor improves compression for various sources of high-precision data.

  11. Laser Doppler flowmetry for measurement of laminar capillary blood flow in the horse

    NASA Astrophysics Data System (ADS)

    Adair, Henry S., III

    1998-07-01

    Current methods for in vivo evaluation of digital hemodynamics in the horse include angiography, scintigraphy, Doppler ultrasound, electromagnetic flow and isolated extracorporeal pump perfused digit preparations. These techniques are either non-quantifiable, do not allow for continuous measurement, require destruction of the horse orare invasive, inducing non- physiologic variables. In vitro techniques have also been reported for the evaluation of the effects of vasoactive agents on the digital vessels. The in vitro techniques are non-physiologic and have evaluated the vasculature proximal to the coronary band. Lastly, many of these techniques require general anesthesia or euthanasia of the animal. Laser Doppler flowmetry is a non-invasive, continuous measure of capillary blood flow. Laser Doppler flowmetry has been used to measure capillary blood flow in many tissues. The principle of this method is to measure the Doppler shift, that is, the frequency change that light undergoes when reflected by moving objects, such as red blood cells. Laser Doppler flowmetry records a continuous measurement of the red cell motion in the outer layer of the tissue under study, with little or no influence on physiologic blood flow. This output value constitutes the flux of red cells and is reported as capillary perfusion units. No direct information concerning oxygen, nutrient or waste metabolite exchange in the surrounding tissue is obtained. The relationship between the flowmeter output signal and the flux of red blood cells is linear. The principles of laser Doppler flowmetry will be discussed and the technique for laminar capillary blood flow measurements will be presented.

  12. Calibration of echocardiographic tissue doppler velocity, using simple universally applicable methods

    NASA Astrophysics Data System (ADS)

    Dhutia, Niti M.; Zolgharni, Massoud; Willson, Keith; Cole, Graham; Nowbar, Alexandra N.; Manisty, Charlotte H.; Francis, Darrel P.

    2014-03-01

    Some of the challenges with tissue Doppler measurement include: apparent inconsistency between manufacturers, uncertainty over which part of the trace to make measurements and a lack of calibration of measurements. We develop and test tools to solve these problems in echocardiography laboratories. We designed and constructed an actuator and phantom setup to produce automatic reproducible motion, and used it to compare velocities measured using 3 echocardiographic modalities: M-mode, speckle tracking, and tissue Doppler, against a non-ultrasound, optical gold standard. In the clinical phase, 25 patients underwent M-mode, speckle tracking and tissue Doppler measurements of tissue velocities. In-vitro, the M-mode and speckle tracking velocities were concordant with optical assessment. Of the three possible tissue Doppler measurement conventions (outer, middle and inner line) only the middle line agreed with the optical assessment (discrepancy -0.20 (95% confidence interval -0.44 to 0.03)cm/s, p=0.11, outer +5.19(4.65 to 5.73)cm/s, p<0.0001, inner -6.26(-6.87 to -5.65)cm/s, p<0.0001). All 4 studied manufacturers showed a similar pattern. M-mode was therefore chosen as the in-vivo gold standard. Clinical measurements of tissue velocities by speckle tracking and the middle line of the tissue Doppler were concordant with M-mode, while the outer line significantly overestimated (+1.27(0.96 to 1.59)cm/s, p<0.0001) and the inner line underestimated (-1.81(-2.11 to -1.52)cm/s, p<0.0001). Echocardiographic velocity measurements can be calibrated by simple, inexpensive tools. We found that the middle of the tissue Doppler trace represents velocity correctly. Echocardiographers requiring velocities to match between different equipment, settings or modalities should use the middle line as the "guideline".

  13. Lung ultrasound in the critically ill

    PubMed Central

    2014-01-01

    in adults), many disciplines (pulmonology, cardiology…), austere countries, and a help in any procedure (thoracentesis). A 1992, cost-effective gray-scale unit, without Doppler, and a microconvex probe are efficient. Lung ultrasound is a holistic discipline for many reasons (e.g., one probe, perfect for the lung, is able to scan the whole-body). Its integration can provide a new definition of priorities. The BLUE-protocol and FALLS-protocol allow simplification of expert echocardiography, a clear advantage when correct cardiac windows are missing. PMID:24401163

  14. Value of combined cross sectional and Doppler echocardiography in the detection of left ventricular pseudoaneurysm after mitral valve replacement.

    PubMed Central

    Kupari, M; Verkkala, K; Maamies, T; Härtel, G

    1987-01-01

    The development of a left ventricular pseudoaneurysm is a rare complication of heart surgery. Until recently it has been impossible to detect without an angiographic study of the left ventricle. A combination of cross sectional and Doppler ultrasound studies led to the correct diagnosis in two patients with left ventricular pseudoaneurysms after mitral valve replacement. Cross sectional echocardiography showed a posterolateral echo-free space confined only by the pericardium and communicating with the left ventricle through a defect in the ventricular wall, and Doppler echocardiography confirmed the presence of blood flow in this cavity. This Doppler finding is critical if the perforation is too small to be identified reliably by cross sectional imaging. Surgical repair of the pseudoaneurysm can be undertaken without invasive studies if the echocardiographic findings are unequivocal and there is no reason to suspect the integrity of the circumflex coronary artery. Images Fig 1 Fig 2 Fig 3 Fig 4 Fig 5 PMID:3620242

  15. Doppler ultrasonic detection of particulate release during hemodialysis with cellulose hollow-fiber and sorbent suspension reciprocating dialyzers.

    PubMed

    Badylak, S F; Ash, S R; Thornhill, J A; Carr, D J

    1984-05-01

    Doppler ultrasound is a noninvasive technique for monitoring moving objects such as flowing blood while ignoring stationary objects such as shunt tubing. A Doppler system was investigated to determine its sensitivity in detecting particulate release in blood during hemodialysis. Seven hemodialysis procedures with dogs and six trials with humans were done using a sorbent suspension reciprocating dialyzer ( SSRD ). Two additional trials were done with humans using a cellulose acetate hollow-fiber dialyzer (HFD). A large increase (approximately twofold) was found in the reflected Doppler signal in outflowing blood from the SSRD and HFD in both dogs and humans. Numerous additional studies to characterize the nature of the particulate matter showed platelet aggregates in the dogs and fibrinogen-fibrin degradation products in the humans to be present in the outflowing blood. In vitro studies suggested microscopic air bubbles (less than 25 micron in diameter) may have contributed to the particulate matter detected during hemodialysis by this sensitive monitoring system.

  16. Covert contrast in velar fronting: An acoustic and ultrasound study

    PubMed Central

    Byun, Tara McAllister; Buchwald, Adam; Mizoguchi, Ai

    2016-01-01

    There is growing evidence that speech sound acquisition is a gradual process, with instrumental measures frequently revealing covert contrast in errors perceived to involve phonemic substitution. Ultrasound imaging has the potential to expand our understanding of covert contrast by showing whether a child uses different tongue shapes while producing sounds that are perceived as neutralized. This study used an ultrasound measure (Dorsum Excursion Index) and acoustic measures (VOT and spectral moments of the burst) to investigate overt and covert contrast between velar and alveolar stops in child speech. Participants were two children who produced a perceptually overt velar-alveolar contrast and two children who neutralized the contrast via velar fronting. Both acoustic and ultrasound measures revealed significant differences between perceptually distinct velar and alveolar targets. One child with velar fronting demonstrated covert contrast in one acoustic and one ultrasound measure; the other showed no evidence of contrast. Clinical implications are discussed. PMID:26325303

  17. Doppler-width thermodynamic thermometry by means of line-absorbance analysis

    SciTech Connect

    Castrillo, A.; De Vizia, M. D.; Gianfrani, L.; Moretti, L.; Galzerano, G.; Laporta, P.; Merlone, A.

    2011-09-15

    A clean and effective implementation of Doppler-width thermometry is described. Exploiting the relationship between line-center absorbance and integrated absorbance, the Doppler width of a molecular spectral line can be retrieved from a set of profiles resulting from different gas pressures. The method is validated by its application to numerically simulated spectra. Preliminary experiments, in water vapor samples, turn out to be successful, demonstrating Doppler-widths' retrieval in the near-infrared with a precision of 8x10{sup -5}, at the water triple point temperature. The direct link to the Boltzmann constant makes the proposed method very attractive for temperature metrology as a tool for the realization of a new thermodynamic temperature scale.

  18. Application of FFT-analyzed umbilical artery doppler signals to fuzzy algorithm.

    PubMed

    Hardalaç, Fýrat; Biri, Aydan; Sucak, Ayhan

    2004-12-01

    Doppler signals, recorded from the umbilical artery of 60 women with pregnancy, were transferred to personal computer via a 16-bit sound card. The fast Fourier transform (FFT) method was applied to the recorded signal from each patient. Because FFT method inherently cannot offer a good spectral resolution at highly turbulent blood flows, it sometimes causes wrong interpretation of Doppler signals. In order to avoid this problem, umbilical artery Doppler blood flow velocity parameters were introduced to a fuzzy algorithm. It is observed that the fuzzy algorithm gives true results for interpretation of umbilical artery blood flow velocity parameters. Forty-five blood flow velocity parameters of 60 women with pregnancy and 15 parameters in training data have been used in a fuzzy system as testing data. The overall success ratio in training data and the testing data were 95.55 and 93.35% respectively.

  19. [The usefulness of range-gated pulsed Doppler echocardiography. A review (author's transl)].

    PubMed

    Lange, L; Allen, H D; Goldberg, S J; Sahn, D J

    1979-03-01

    Single-crystal RGPD Echocardiography has clearly become a useful noninvasive ultrasonic method which enlarges the capabilities of investigating the heart. Recording of flow direction and showing disturbed flow allows additional clarification and confirmation of various diagnoses. This single-crystal technique does not allow flow quantification at the present time. The TIH and auditory signal displays of Doppler shift as presently utilized in commercial devices allow qualitative observation but require much experience in test performance and evaluation. The future here is probably in the area of spectral analysis. Present instrumentation employs M-mode echo for Doppler sample localization. Drawbacks include inprecise sample beam localization and non-variable sample volume size. Further, standardization of the Doppler signal is necessary. Combination with 2-D echo in the future will allow more precise sample beam localization and accuracy in flow quantification. The latter area has particular promise and is under investigation but is not yet commercially available.

  20. Airborne Differential Doppler Weather Radar

    NASA Technical Reports Server (NTRS)

    Meneghini, R.; Bidwell, S.; Liao, L.; Rincon, R.; Heymsfield, G.; Hildebrand, Peter H. (Technical Monitor)

    2001-01-01

    The Precipitation Radar aboard the Tropical Rain Measuring Mission (TRMM) Satellite has shown the potential for spaceborne sensing of snow and rain by means of an incoherent pulsed radar operating at 13.8 GHz. The primary advantage of radar relative to passive instruments arises from the fact that the radar can image the 3-dimensional structure of storms. As a consequence, the radar data can be used to determine the vertical rain structure, rain type (convective/stratiform) effective storm height, and location of the melting layer. The radar, moreover, can be used to detect snow and improve the estimation of rain rate over land. To move toward spaceborne weather radars that can be deployed routinely as part of an instrument set consisting of passive and active sensors will require the development of less expensive, lighter-weight radars that consume less power. At the same time, the addition of a second frequency and an upgrade to Doppler capability are features that are needed to retrieve information on the characteristics of the drop size distribution, vertical air motion and storm dynamics. One approach to the problem is to use a single broad-band transmitter-receiver and antenna where two narrow-band frequencies are spaced apart by 5% to 10% of the center frequency. Use of Ka-band frequencies (26.5 GHz - 40 GHz) affords two advantages: adequate spatial resolution can be attained with a relatively small antenna and the differential reflectivity and mean Doppler signals are directly related to the median mass diameter of the snow and raindrop size distributions. The differential mean Doppler signal has the additional property that this quantity depends only on that part of the radial speed of the hydrometeors that is drop-size dependent. In principle, the mean and differential mean Doppler from a near-nadir viewing radar can be used to retrieve vertical air motion as well as the total mean radial velocity. In the paper, we present theoretical calculations for the