The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
Flow velocity estimation is an important feature in ultrasound imaging. However, in conventional color Doppler imaging, only parallel flow components can be estimated, the velocity information is not simultaneously measured throughout the region of interest (ROI) due to sequential firing of the ultrasound beams, and the size of the ROI is limited under frame rate concerns. On the other hand, ultrafast...
Pulse wave velocity (PWV) is a reliable index of arterial stiffness. To date, reflected pulse wave interference is still a major challenge for regional PWV estimation using ultrasound imaging methods. In this study, a high-resolution Radon transform (HRT) method is proposed to eliminate the reflected wave interferences in PWV estimation.
Displacement estimation is a critical component of elastography. The measurement of sub-resolution displacements relies on high cross-correlation (CC) between repeated collinear RF acquisitions. CCs are degraded by common sources of acoustic noise, such as reverberation clutter, in addition to the displacement of scatterers within the radiation force field. CCs are also degraded spatially across the...
We have recently demonstrated the feasibility of vascular guided wave imaging (VGWI) in non-invasive estimation of bi-plane (i.e., longitudinal and transverse) transmural arterial Young's modulus (ELV, ETV) in tubular phantoms using phase velocity (cph) (Guo et al., ITEC 2016). In this study, we further compare the ETV estimated from the circumferential Lamb type (CLT) wave by VGWI with ETP from the...
In vivo estimation of attenuation coefficients is useful because of its potential for tissue characterization and relevance in accurate backscatter coefficient estimation. However, current methods based on spectral analysis for ultrasonic attenuation estimation suffer from a severe trade-off between estimation precision and spatial resolution. Recently, the regularized spectral log difference (RSLD)...
The estimation of Ultrasound-Contrast-Agent (UCA) kinetics from Dynamic Contrast-Enhanced Ultrasound (DCE-US) recordings has shown promise to localize prostatic malignancy. In a two-dimensional (2D) approach, UCA dispersion and velocity provide a characterization of the prostate (micro)vasculature with diagnostic value [1]. To this end, the UCA transport kinetics are modelled with strong assumptions...
The technique of non-invasive cortical bone quality assessment using ultrasound axial transmission has attracted considerable attention. Estimating the phase velocity and the attenuation of the absorbing plate will assist the assessment. Among several techniques proposed for these purposes, many employ either a thresholding process or a peak search process. The thresholding process uses the intensity...
In pulse compression using an M-sequence, the M-sequence modulated signal is transmitted and the received signal is correlated with the transmitted signal. However, the M-sequence modulated signal reflected from a moving object is Doppler-shifted. The Doppler-shifted M-sequence modulated signal cannot be correlated with the transmitted signal. Therefore, Doppler velocity estimation from a cyclic M-sequence...
Developing tools to visualize urinary flow dynamics is important, because urinary hydrodynamics is known to have a causal relationship with urethral voiding dysfunction problems. Yet, the design of such an imaging technique is challenging as fine time resolution is essential to track urine passage that can traverse at >2m/s speeds. Previously, we have overcome the time resolvability challenge in...
The Reference Phantom Method can be used to quantify acoustic properties of tissue by compensating for system effects using the average power spectrum from a well-characterized homogeneous medium. Widespread clinical application of the Reference Phantom Method is hindered by the need to scan the reference phantom using the same transducer, system, and system settings as used for scanning the tissue...
Pressure measurements within the chambers of the heart yield critical information for diagnosis and management of cardiac patients (∼92 million Americans), but cardiac catheterization procedure is invasive and expensive. Subharmonic aided pressure estimation (SHAPE) may be able to estimate intra-cardiac pressures noninvasively, if the optimum incident acoustic output (IAO) for SHAPE can be established...
Subharmonic aided pressure estimation (SHAPE) is based on the inverse relationship between the subharmonic amplitude of contrast microbubbles and the ambient pressure. A noninvasive ultrasound based pressure estimation procedure would be a major development in the diagnosis of portal hypertension and less invasive than the current hepatic venous pressure gradient (HVPG) measurement. The hypothesis...
Pulse wave velocity and blood flow velocity are two different physiological parameters which are generally assessed using two different ultrasound sequences and processing techniques. This can be explained by the difference in term of signal intensity between the tissue and blood (approx. 40 dB). On one side, blood velocity can be estimated using Doppler, speckle tracking or transverse oscillation...
Functional ultrasound (fUS) imaging is novel neuroimaging modality for brain activity based on the neurovascular coupling. This technique provides non-invasive dynamic mapping of the cerebral blood volume (CBV) variations through high-sensitivity power Doppler measurements. Complementary to CBV measurements, it would be of particular interest to extend fUS to cerebral blood flow (CBF) measurements...
The shift to software beamforming has inspired a myriad of adaptive beamformers. Some of these overestimate which signals originate from sidelobes and which originate from the mainlobe. This results in a Dark Region Artifact (DRA) next to hyperechoic targets. We investigate this artifact for seven beamformers: Delay-And-Sum (DAS), the Coherence Factor (CF), Generalized Coherence Factor (GCF), Phase...
In ultrasound examination of thin multi-layered materials, the received signal is, in both through-transmission and pulse-echo configurations, a superposition of multiple reflections from inside the sample. If the layer thicknesses are small compared to the duration of the emitted ultrasound pulse, the received signal will be a sum of overlapping ultrasound pulses. In such scenarios, estimation of...
Electronic fetal heart rate (fHR) monitoring is standard in clinical practice to detect deviations from the normal fHR pattern. Typically, an ultrasound (US) transducer, operating in a pulsedwave Doppler mode, measures the periodic motion of the fetal heart, from which the fHR can be derived. However, as the fetus moves through the birth canal, the fetal-heart location (fHL) changes continuously....
Quasi-static elastography is a widely applied ultrasound method in which RF data acquired in tissue at different states of deformation are correlated to estimate displacements and strain (displacement gradient). A recent development is the introduction of ultrafast plane-wave imaging where element data are beam-formed after collection to reconstruct the image lines. Several beam-forming strategies...
Several challenges limit the use of Pulsed Wave (PW) Doppler to assess coronary blood flow: 1) Transit time effect causes spectral broadening in regions with high blood flow such as stenoses, leading to overestimation of maximum velocities. 2) High beam to flow angles (>60°) and out of plane components often occur, making manual positioning of the sample volume and angle correction difficult. 2D...
Ultrasound shear wave imaging is a rapidly emerging technique that noninvasively quantifies shear wave speed (SWS), which is directly linked to the stiffness of soft tissues. Targeting sources of estimation errors entailed in in vivo data, previous studies have proposed different methods, e.g. radon sum (RS) (Rouze et al. 2010), under the assumption of tissue homogeneity, which significantly limits...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.