scholarly journals Combined spatiotemporal and frequency-dependent shear wave elastography enables detection of vulnerable carotid plaques as validated by MRI

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
David Marlevi ◽  
Sharon L. Mulvagh ◽  
Runqing Huang ◽  
J. Kevin DeMarco ◽  
Hideki Ota ◽  
...  
Keyword(s):  
Phase Velocity ◽  
Group Velocity ◽  
Shear Wave ◽  
Shear Wave Elastography ◽  
Intraplaque Hemorrhage ◽  
Frequency Dependent ◽  
Invasive Approach ◽  
Carotid Plaques ◽  
Phase Velocities ◽  
Luminal Narrowing

AbstractFatal cerebrovascular events are often caused by rupture of atherosclerotic plaques. However, rupture-prone plaques are often distinguished by their internal composition rather than degree of luminal narrowing, and conventional imaging techniques might thus fail to detect such culprit lesions. In this feasibility study, we investigate the potential of ultrasound shear wave elastography (SWE) to detect vulnerable carotid plaques, evaluating group velocity and frequency-dependent phase velocities as novel biomarkers for plaque vulnerability. In total, 27 carotid plaques from 20 patients were scanned by ultrasound SWE and magnetic resonance imaging (MRI). SWE output was quantified as group velocity and frequency-dependent phase velocities, respectively, with results correlated to intraplaque constituents identified by MRI. Overall, vulnerable lesions graded as American Heart Association (AHA) type VI showed significantly higher group and phase velocity compared to any other AHA type. A selection of correlations with intraplaque components could also be identified with group and phase velocity (lipid-rich necrotic core content, fibrous cap structure, intraplaque hemorrhage), complementing the clinical lesion classification. In conclusion, we demonstrate the ability to detect vulnerable carotid plaques using combined SWE, with group velocity and frequency-dependent phase velocity providing potentially complementary information on plaque characteristics. With such, the method represents a promising non-invasive approach for refined atherosclerotic risk prediction.

scholarly journals Ultrasound Elastography: another piece in the puzzle of carotid plaque vulnerability?

2021 ◽  
Author(s):  
Andjoli Davidhi ◽  
Vasileios Rafailidis ◽  
Evangelos Destanis ◽  
Panos Prassopoulos ◽  
Stefanos Foinitsis
Keyword(s):  
Shear Wave ◽  
Carotid Plaque ◽  
Diagnostic Yield ◽  
Imaging Modality ◽  
Shear Wave Elastography ◽  
Ultrasound Elastography ◽  
Intraplaque Hemorrhage ◽  
Plaque Vulnerability ◽  
Carotid Plaques ◽  
Increased Risk

Recent literature has shown that various carotid plaque features, other than stenosis, contribute to plaque vulnerability. Features such as surface morphology and plaque composition with distinct components (e.g. intraplaque hemorrhage, lipid core) have been associated with the increased risk of future cerebrovascular events. Ultrasonography constitutes the first line modality for the assessment of carotid disease and has traditionally been used to grade stenosis with high accuracy. Recenttechnological advances such as contrast-enhanced ultrasound and elastography increased the diagnostic yield of ultrasound in assessing the morphology of carotid plaques. The purpose of this review is to present the available literature on ultrasound elastography of the atherosclerotic carotid. Strain and shear wave elastography allow for the characterization of plaque components, thus indicating its nature and importantly, the plaque’s vulnerability. Shear wave elastography indices appear morerobust than Strain indices. Overall, elastography is a feasible method to distinguish vulnerable carotid plaques. There is, however, a need for larger and longer prospective controlled clinical studies in order to validate elastography as an imaging modality used for the detection of unstable carotid plaques.

scholarly journals Author Correction: Combined spatiotemporal and frequency-dependent shear wave elastography enables detection of vulnerable carotid plaques as validated by MRI

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
David Marlevi ◽  
Sharon L. Mulvagh ◽  
Runqing Huang ◽  
J. Kevin DeMarco ◽  
Hideki Ota ◽  
...  
Keyword(s):  
Shear Wave ◽  
Shear Wave Elastography ◽  
Frequency Dependent ◽  
Carotid Plaques

Do traveltimes in pulse‐transmission experiments yield anisotropic group or phase velocities?

Geophysics ◽  
1994 ◽  
Vol 59 (11) ◽  
pp. 1774-1779 ◽  
Author(s):  
Joe Dellinger ◽  
Lev Vernik
Keyword(s):  
Phase Velocity ◽  
Group Velocity ◽  
Elastic Constants ◽  
Near Field ◽  
Frequency Dispersion ◽  
Transversely Isotropic ◽  
Sh Waves ◽  
Phase Velocities ◽  
Pulse Transmission ◽  
Transmission Technique

The elastic properties of layered rocks are often measured using the pulse through‐transmission technique on sets of cylindrical cores cut at angles of 0, 90, and 45 degrees to the layering normal (e.g., Vernik and Nur, 1992; Lo et al., 1986; Jones and Wang, 1981). In this method transducers are attached to the flat ends of the three cores (see Figure 1), the first‐break traveltimes of P, SV, and SH‐waves down the axes are measured, and a set of transversely isotropic elastic constants are fit to the results. The usual assumption is that frequency dispersion, boundary reflections, and near‐field effects can all be safely ignored, and that the traveltimes measure either vertical anisotropic group velocity (if the transducers are very small compared to their separation) or phase velocity (if the transducers are relatively wide compared to their separation) (Auld, 1973).

Wall Pressure Phase Velocity Measurements in a Turbulent Boundary Layer

2012 ◽  
Author(s):  
Teresa S. Miller ◽  
Mark J. Moeller
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Phase Velocity ◽  
Group Velocity ◽  
Noise Source ◽  
Wall Pressure ◽  
Interior Noise ◽  
Convection Velocity ◽  
Phase Velocities ◽  
Wall Pressure Fluctuation

The turbulent boundary layer that forms on the outer surfaces of vehicles can be a significant source of interior noise. In automobiles this is known as wind noise, and at high speeds it dominates the interior noise. For airplanes the turbulent boundary is also a dominant noise source. Because of its importance as a noise source, it is desirable to have a model of the turbulent wall pressure fluctuations for interior noise prediction. One important parameter in building the wall pressure fluctuation model is the convection velocity. In this paper, the phase velocity was determined from the streamwise pressure measurements. The phase velocity was calculated for three separation distances ranging from 0.25 to 1.30 boundary layer thicknesses. These measurements were made for a Mach number range of 0.1 < M < 0.6. The phase velocity was shown to vary with sensor spacing and frequency. The data collapsed well on outer variable normalization. The phase velocities were fit and the group velocity was calculated from the curve fit. The group velocity was consistent with the array measured convection velocities. The group velocity was also estimated by a band limited cross correlation technique that used the Hilbert transform to find the energy delay. This result was consistent with the group velocity inferred from the phase velocities and the array measured convection velocity. From this research, it is suggested that the group velocity found in this study should be used to estimate the convection velocity in wall pressure fluctuation models.

scholarly journals Does group velocity always reflect elastic modulus in shear wave elastography?

2019 ◽  
Vol 24 (07) ◽  
pp. 1 ◽  
Author(s):  
Ivan Pelivanov ◽  
Liang Gao ◽  
John Pitre ◽  
Mitchell A. Kirby ◽  
Shaozhen Song ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Group Velocity ◽  
Shear Wave ◽  
Shear Wave Elastography

Abstract 140: High Intensity Signals on Mip Images of Carotid Atherosclerotic Plaques Detected by Routine Three Dimensional Magnetic Resonance Angiography Are Associated With Ischemic Strokes

Stroke ◽  
2015 ◽  
Vol 46 (suppl_1) ◽  
Author(s):  
Kiyofumi Yamada ◽  
Masanori Kawasaki ◽  
Shinichi Yoshimura ◽  
Shigehiro Nakahara ◽  
Yoshikazu Sato
Keyword(s):  
Magnetic Resonance ◽  
High Intensity ◽  
Three Dimensional ◽  
Multivariate Logistic Regression Analysis ◽  
Maximum Intensity Projection ◽  
Intraplaque Hemorrhage ◽  
Carotid Plaques ◽  
Symptomatic Carotid ◽  
Tof Mra ◽  
Luminal Narrowing

Background: Carotid artery stenosis is one of the major causes of ischemic strokes. Carotid intraplaque hemorrhage (IPH) has been associated with accelerated plaque growth, luminal narrowing and development of symptomatic events. Maximum intensity projection images are easily reformatted from four to five minute, routine, clinical TOF sequences. The aim of this study was to evaluate the relationships between high intensity signal (HIS) in carotid plaques on MIP images detected by routine three dimensional magnetic resonance imaging (3D-TOF MRA) and ischemic strokes. Materials and Methods: Sixty patients with carotid stenosis ≥ 50% (North American Symptomatic Carotid Endarterectomy Trial criteria) were included. Carotid IPH was defined as the presence of HIS in carotid plaques on MIP images detected by 3DTOF MRA using the criteria previously we reported. We analyzed the relation between the presence of HIS in the plaques and prior ischemic strokes defined as ischemic lesions on diffusion weighed images of the brain. Results: HISs in carotid plaque were present in 27 (44%) of 61 carotid arteries in 60 patients. Prior ipsilateral ischemic strokes occurred more frequently in HIS positive group (17 of 27, 63%) than HIS negative group (3 of 34; 9%) [p<0.001]. In multivariate logistic regression analysis, HIS was the only independent predictor of prior ischemic strokes after being adjusted by age, cardiovascular risk factors, degree of stenosis and history of ischemic heart disease [Odds ratio: 23.0 (95%CI: 5.1 - 103.1), p<0.001]. Conclusions: HISs in carotid plaques on 3DTOF-MRA MIP images are the only independent determinant of prior ischemic strokes, and they can potentially provide a reliable risk stratification of carotid plaques.

scholarly journals Shear wave elastography imaging of carotid plaques: feasible, reproducible and of clinical potential

2014 ◽  
Vol 12 (1) ◽  
Author(s):  
Kumar V Ramnarine ◽  
James W Garrard ◽  
Baris Kanber ◽  
Sarah Nduwayo ◽  
Timothy C Hartshorne ◽  
...  
Keyword(s):  
Shear Wave ◽  
Shear Wave Elastography ◽  
Carotid Plaques ◽  
Clinical Potential

scholarly journals Local Phase Velocity Based Imaging: A New Technique Used for Ultrasound Shear Wave Elastography

2019 ◽  
Vol 38 (4) ◽  
pp. 894-908 ◽  
Author(s):  
Piotr Kijanka ◽  
Matthew W. Urban
Keyword(s):  
Phase Velocity ◽  
Shear Wave ◽  
Shear Wave Elastography ◽  
New Technique ◽  
Local Phase ◽  
A New Technique
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