Search results for " Doppler"
showing 10 items of 373 documents
US-Elastography for Breast Lesion Characterization: Prospective Comparison of US BIRADS, Strain Elastography and Shear wave Elastography
2020
To evaluate the diagnostic performance of strain elastography (SE) and 2 D shear wave elastography (SWE) and SE/SWE combination in comparison with conventional multiparametric ultrasound (US) with respect to improving BI-RADS classification results and differentiating benign and malignant breast lesions using a qualitative and quantitative assessment. In this prospective study, 130 histologically proven breast masses were evaluated with baseline US, color Doppler ultrasound (CDUS), SE and SWE (Toshiba Aplio 500 with a 7-15 MHz wide-band linear transducer). Each lesion was classified according to the BIRADS lexicon by evaluating the size, the B-mode and color Doppler features, the SE qualit…
Use of middle cerebral velocity and blood pressure for the analysis of cerebral autoregulation at various frequencies: The coherence index
1998
A common component in many protocols for the evaluation of cerebral autoregulation is the comparison of transcranial Doppler ultrasound (TCD) velocities with blood pressure recordings, in which correlations between these two signals correspond to impaired autoregulation. With long data sets and complicated paradigms, however, visual inspection alone cannot adequately distinguish random coincidence from consistent correlation in a statistically valid fashion. We suggest and illustrate the use of the coherence index for this purpose. To illustrate this technique, long-term recordings of TCD velocity and blood pressure were obtained from 6 normal subjects and using 23 data segments from 8 pati…
A Comprehensive Ultrasonographic Assessment of Pediatric and Adolescent Varicocele Can Improve Surgical Results.
2020
<b><i>Purpose:</i></b> Undetected refluxing venous systems could cause persistence/recurrence of varicoceles in patients undergoing varicocelectomy. Color Doppler ultrasound (CDUS) is an important tool in the diagnosis and follow-up of varicocele, and could be successfully used to detect a venous reflux in the iliac-deferential district, usually involved in the recurrence/persistence of varicocele. <b><i>Materials and Methods:</i></b> We compared 2 historical series of patients treated with Palomo laparoscopic varicocelectomy between 1994 and 2018. In group 1, preoperative scrotal CDUS was obtained, while in group 2, additional inguinal CDUS w…
Qualitative and quantitative evaluation of solitary thyroid nodules with contrast-enhanced ultrasound: initial results
2005
To assess the feasibility of contrast-enhanced ultrasound (CEUS) of the thyroid gland and to evaluate the potential of this method for characterising solitary thyroid nodules.18 patients affected by solitary thyroid nodules (size range: 0.6 to 3.6 cm; mean: 1.8 cm) confirmed by surgery (nine papillary carcinomas, four follicular carcinomas, three hyperplasias, one follicular adenoma and one Plummer’s adenoma) underwent pulse inversion US at low M.I. (0.06 to 0.08) after i.v. injection of a 2.4-mL bolus of SonoVue. Baseline echogenicity and the dynamic enhancement pattern of each nodule, in comparison with adjacent thyroid parenchyma, were assessed. Signal intensity values on grey-scale imag…
Analysing longitudinal turbulence intensity in vegetated channels
2007
Vegetation altering hydrodynamic conditions of an open channel flow controls the exchanges of sediment, nutrients and contaminants. In this paper the turbulence structure of open-channel flow over a flexible grass vegetation is investigated. Velocity measurements were carried out, in a rectangular flume, using a 2D-ADV (Acoustic Doppler Velocimeter) for different values of stem concentration, water discharge, and bed slope. The experimental results showed that: 1) the maximum value of the longitudinal turbulence intensity occurs at a water depth close to the bent vegetation height; 2) the turbulence intensity damps for increasing values of the stem concentration; 3) above the vegetation hei…
Utilidad del color doppler, power doppler y el contraste sonográfico en el diagnóstico por imagen del cáncer de próstata localizado
2012
Objetivos: 1º. Estudiar el rendimiento diagnóstico de la ecografía transrectal en escala de grises, power doppler y del contraste sonográfico en el diagnóstico precoz por imagen del cáncer de próstata localizado. 2º. Comparar la rentabilidad diagnóstica de la biopsia prostática aleatoria con la biopsia ecodirigida mediante power doppler y contraste sonográfico, en el diagnóstico precoz por imagen del cáncer de próstata localizado. Material y métodos: Se diseñó un estudio epidemiológico prospectivo y transversal de ámbito provincial, para estudiar el rendimiento diagnóstico de la ecografía transrectal en escala de grises (EG), Power Doppler (PD) y del contraste sonográfico (CS) en el diagnós…
A combination of umbilical artery PI and normalized blood flow volume in the umbilical vein: Venous–arterial index for the prediction of fetal outcome
2008
Abstract Objective The objective was to assess the diagnostic power of the umbilical venous–arterial index (VAI) as a combination of the pulsatility index in the umbilical artery and the normalized blood flow volume in the umbilical vein for the prediction of poor fetal outcome. Study design This was a prospective clinical study in which the umbilical artery PI (UAPI), the normalized umbilical vein blood volume flow rate ( n UV; ml/min/kg estimated fetal body weight), the venous–arterial index (VAI; n UV/UAPI), and the pulsatility index (PI) in the umbilical artery (UA), uterine artery (utA), middle cerebral artery (MCA), and aorta were determined in 181 fetuses once (at between 17 and 41 w…
Performance Analysis of Sweep-Spread Carrier (S2C) Modulation for Underwater Communications
2022
In the last decades, underwater acoustic communications have seen a growing development with a variety of research as well as commercial applications, dealing with channel distortions, multipath and Doppler effects typical underwater channels. A very robust modulation able to guarantee connectivity in harsh environments (where spectral efficient solutions such as OFDM can be prevented) is the so called sweep-spread carrier (S2C) modulation, which is based on the usage of a linearly time-varying carrier. Underwater modems based on S2C modulations have been patented and successfully adopted in real-world deployments. In this paper, we analyze the performance of S2C both in simulation and infi…
Experiments and predictions of the transition of the flow pattern with impeller clearance in stirred tanks
2001
In the present work, the double- to single-loop flow pattern transition in a stirred vessel equipped with a Rushton turbine is investigated by Laser Doppler anemometry (LDA). In particular, the clearance at which such transition occurs is assessed by comparing axial velocity profiles underneath the impeller. Computational fluid dynamics (CFD) simulations of the same system are carried out, by employing the 'inner-outer' fully predictive computation strategy. The comparison of predicted results with the experimental data collected shows that the transition is well reproduced by simulations. A good agreement on the mean velocities is also observed but for the impeller discharge stream angle t…
Asymptomatic carotid lesions add to cardiovascular risk prediction.
2010
AIM To show that subclinical atherosclerosis (subclinical-ATS) of carotid arteries [intima-media thickness (IMT) or asymptomatic carotid plaque (ACP)], may provide additional information for risk stratification, in asymptomatic patients, aged greater than 45 years, with a cluster of risk factors (RFs). METHODS AND RESULTS We studied 558 asymptomatic patients (235 males). RFs for atherosclerosis were assessed and the 10-year-risk was calculated according to the Italian risk score. Doppler ultrasound of carotid arteries identified the presence of IMT greater than 0.9 mm in 183 patients and ACP in 147 patients. One hundred and fifty-three patients developed cerebrovascular or cardiovascular (C…