scholarly journals Mechanics of ultrasound elastography

2017 ◽  
Vol 473 (2199) ◽  
pp. 20160841 ◽  
Author(s):  
Guo-Yang Li ◽  
Yanping Cao
Keyword(s):  
Soft Tissues ◽  
Soft Materials ◽  
Ultrasound Elastography ◽  
Practical Applications ◽  
Linear Elastic ◽  
Non Invasive ◽  
Anisotropic Elastic ◽  
Non Destructive

Ultrasound elastography enables in vivo measurement of the mechanical properties of living soft tissues in a non-destructive and non-invasive manner and has attracted considerable interest for clinical use in recent years. Continuum mechanics plays an essential role in understanding and improving ultrasound-based elastography methods and is the main focus of this review. In particular, the mechanics theories involved in both static and dynamic elastography methods are surveyed. They may help understand the challenges in and opportunities for the practical applications of various ultrasound elastography methods to characterize the linear elastic, viscoelastic, anisotropic elastic and hyperelastic properties of both bulk and thin-walled soft materials, especially the in vivo characterization of biological soft tissues.

scholarly journals Why Are Viscosity and Nonlinearity Bound to Make an Impact in Clinical Elastographic Diagnosis?

Sensors ◽  
2020 ◽  
Vol 20 (8) ◽  
pp. 2379 ◽  
Author(s):  
Guillermo Rus ◽  
Inas H. Faris ◽  
Jorge Torres ◽  
Antonio Callejas ◽  
Juan Melchor
Keyword(s):  
Soft Tissues ◽  
Elastic Parameters ◽  
Tissue Microstructure ◽  
Non Invasive ◽  
Recent Developments ◽  
Mechanical Biomarkers ◽  
Nonlinear Elastic

The adoption of multiscale approaches by the biomechanical community has caused a major improvement in quality in the mechanical characterization of soft tissues. The recent developments in elastography techniques are enabling in vivo and non-invasive quantification of tissues’ mechanical properties. Elastic changes in a tissue are associated with a broad spectrum of pathologies, which stems from the tissue microstructure, histology and biochemistry. This knowledge is combined with research evidence to provide a powerful diagnostic range of highly prevalent pathologies, from birth and labor disorders (prematurity, induction failures, etc.), to solid tumors (e.g., prostate, cervix, breast, melanoma) and liver fibrosis, just to name a few. This review aims to elucidate the potential of viscous and nonlinear elastic parameters as conceivable diagnostic mechanical biomarkers. First, by providing an insight into the classic role of soft tissue microstructure in linear elasticity; secondly, by understanding how viscosity and nonlinearity could enhance the current diagnosis in elastography; and finally, by compounding preliminary investigations of those elastography parameters within different technologies. In conclusion, evidence of the diagnostic capability of elastic parameters beyond linear stiffness is gaining momentum as a result of the technological and imaging developments in the field of biomechanics.

scholarly journals Mechanical characterization of functionally graded soft materials with ultrasound elastography

2019 ◽  
Vol 377 (2144) ◽  
pp. 20180075 ◽  
Author(s):  
Guo-Yang Li ◽  
Zhao-Yi Zhang ◽  
Jialin Qian ◽  
Yang Zheng ◽  
Wenli Liu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Dispersion Relation ◽  
Soft Tissues ◽  
Mechanical Characterization ◽  
Applied Mathematics ◽  
Soft Materials ◽  
Functionally Graded ◽  
Ultrasound Elastography ◽  
Transient Wave

Functionally graded soft materials (FGSMs) with microstructures and mechanical properties exhibiting gradients across a spatial volume to satisfy specific functions have received interests in recent years. How to characterize the mechanical properties of these FGSMs in vivo/in situ and/or in a non-destructive manner is a great challenge. This paper investigates the use of ultrasound elastography in the mechanical characterization of FGSMs. An efficient finite-element model was built to calculate the dispersion relation for surface waves in FGSMs. For FGSMs with large elastic gradients, the measured dispersion relation can be used to identify mechanical parameters. In the case where the elastic gradient is smaller than a certain critical value calculated here, our analysis on transient wave motion in FGSMs shows that the group velocities measured at different depths can infer the local mechanical properties. Experiments have been performed on polyvinyl alcohol (PVA) cryogel to demonstrate the usefulness of the method. Our analysis and the results may not only find broad applications in mechanical characterization of FGSMs but also facilitate the use of shear wave elastography in clinics because many diseases change the local elastic properties of soft tissues and lead to different material gradients. This article is part of the theme issue ‘Rivlin's legacy in continuum mechanics and applied mathematics’.

scholarly journals Prevalence and Photobiology of Photosynthetic Dinoflagellate Endosymbionts in the Nudibranch Berghia stephanieae

Animals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 2200
Author(s):  
Ruben X. G. Silva ◽  
Paulo Cartaxana ◽  
Ricardo Calado
Keyword(s):  
Food Deprivation ◽  
Photosynthetic Efficiency ◽  
Rapid Decrease ◽  
Complete Loss ◽  
Symbiotic Association ◽  
Non Invasive ◽  
Sea Slugs ◽  
Non Destructive ◽  
Over Time

Berghia stephanieae is a stenophagous sea slug that preys upon glass anemones, such as Exaiptasia diaphana. Glass anemones host photosynthetic dinoflagellate endosymbionts that sea slugs ingest when consuming E. diaphana. However, the prevalence of these photosynthetic dinoflagellate endosymbionts in sea slugs appears to be short-lived, particularly if B.stephanieae is deprived of prey that host these microalgae (e.g., during bleaching events impacting glass anemones). In the present study, we investigated this scenario, along with food deprivation, and validated the use of a non-invasive and non-destructive approach employing chlorophyll fluorescence as a proxy to monitor the persistence of the association between sea slugs and endosymbiotic photosynthetic dinoflagellates acquired through the consumption of glass anemones. Berghia stephanieae deprived of a trophic source hosting photosynthetic dinoflagellate endosymbionts (e.g., through food deprivation or by feeding on bleached E. diaphana) showed a rapid decrease in minimum fluorescence (Fo) and photosynthetic efficiency (Fv/Fm) when compared to sea slugs fed with symbiotic anemones. A complete loss of endosymbionts was observed within 8 days, confirming that no true symbiotic association was established. The present work opens a new window of opportunity to rapidly monitor in vivo and over time the prevalence of associations between sea slugs and photosynthetic dinoflagellate endosymbionts, particularly during bleaching events that prevent sea slugs from incorporating new microalgae through trophic interactions.

scholarly journals Study of Osteocyte Behavior by High-Resolution Intravital Imaging Following Photo-Induced Ischemia

Molecules ◽  
2018 ◽  
Vol 23 (11) ◽  
pp. 2874
Author(s):  
Hengfeng Yuan ◽  
Wen Jiang ◽  
Yuanxin Chen ◽  
Betty Kim
Keyword(s):  
Imaging Techniques ◽  
Avascular Osteonecrosis ◽  
Functional Changes ◽  
Cellular Processes ◽  
Non Invasive ◽  
Behavioral Dynamics ◽  
Bony Anatomy ◽  
Magnetic Resonance Imaging Mri

Ischemic injuries and local hypoxia can result in osteocytes dysfunction and play a key role in the pathogenesis of avascular osteonecrosis. Conventional imaging techniques including magnetic resonance imaging (MRI) and computed tomography (CT) can reveal structural and functional changes within bony anatomy; however, characterization of osteocyte behavioral dynamics in the setting of osteonecrosis at the single cell resolution is limited. Here, we demonstrate an optical approach to study real-time osteocyte functions in vivo. Using nicotinamide adenine dinucleotide (NADH) as a biomarker for metabolic dynamics in osteocytes, we showed that NADH level within osteocytes transiently increase significantly after local ischemia through non-invasive photo-induced thrombosis of afferent arterioles followed by a steady decline. Our study presents a non-invasive optical approach to study osteocyte behavior through the modulation of local environmental conditions. Thus it provides a powerful toolkit to study cellular processes involved in bone pathologies in vivo.

Beyond Death: Forensic Investigations of pre-Columbian Mummies from the Tarapacá Valley, Chile, Using Variable Pressure SEM and Raman Spectroscopy

2007 ◽  
Vol 15 (6) ◽  
pp. 6-11 ◽  
Author(s):  
S.V. Prikhodko ◽  
C. Fischer ◽  
R. Boytner ◽  
M. C. Lozada ◽  
M. Uribe ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Chemical Characterization ◽  
Quantitative Information ◽  
Mortuary Practices ◽  
Variable Pressure ◽  
Scientific Investigations ◽  
Non Invasive ◽  
Archaeological Materials ◽  
Non Destructive

Variable pressure scanning electron microscopy (VPSEM) coupled with other non-destructive analytical methods, such as energy dispersive (EDS) and Raman spectroscopy (RS) offers new capabilities for non-invasive imaging and chemical characterization of archaeological materials. This article underlines the application of VPSEM-EDS-RS on bioarchaeological specimens of pre-Columbian mummies from the Tarapacá Valley in northern Chile. The aim of the scientific investigations is to identify nonanatomical features and to provide qualitative and quantitative information at molecular levels, complementing the morphological record from studies in physical anthropology, in an effort to understand mortuary practices in the Tarapacá Valley and the effects of the burial environment in the preservation of mummified human remains.

Non-Invasive Measurement of In-Vivo Elasticity of Skeletal Muscles with MR-Elastography

2007 ◽  
Vol 342-343 ◽  
pp. 901-904
Author(s):  
Yu Bong Kang ◽  
T. Oida ◽  
Duk Young Jung ◽  
A. Fukuma ◽  
T. Azuma ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Shear Modulus ◽  
Skeletal Muscles ◽  
Soft Tissues ◽  
Viscosity Coefficient ◽  
Non Invasive ◽  
Novel Method ◽  
Human Calf ◽  
Invasive Measurement

In order to evaluate the mechanical properties of the human skeletal muscles, the elasticity and viscosity of the human calf muscles were measured with Magnetic Resonance Elastography (MRE). MRE is a novel method to measure the mechanical properties of living soft tissues in vivo quantitatively by observing the strain waves propagated in the object. In this study, the shear modulus and viscosity coefficient were measured with MRE. The shear modulus was 3.7 kPa in relaxed state, and increased with increasing the muscle forces. Interestingly, the viscosity was changed with the vibration frequency applied to the muscles, that was 4.5 Pa·s at 100Hz vibration and 2.4 Pa·s at 200Hz vibration. This shows clearly the visco-elastic property.

scholarly journals Non-invasive Characterization of Focal Arrhythmia with Electromechanical Wave Imaging in Vivo

2018 ◽  
Vol 44 (11) ◽  
pp. 2241-2249 ◽  
Author(s):  
Alexandre Costet ◽  
Elaine Wan ◽  
Lea Melki ◽  
Ethan Bunting ◽  
Julien Grondin ◽  
...  
Keyword(s):  
Non Invasive ◽  
Wave Imaging
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