scholarly journals EVALUATION OF IRIDOCILIARY AND LENTICULAR ELASTICITY USING SHEAR-WAVE ELASTOGRAPHY IN RABBIT EYES

2014 ◽  
Vol 57 (1) ◽  
pp. 9-14 ◽  
Author(s):  
Efstathios T. Detorakis ◽  
Eleni E. Drakonaki ◽  
Harilaos Ginis ◽  
Nikolaos Karyotakis ◽  
Ioannis G. Pallikaris
Keyword(s):  
Shear Wave ◽  
Ciliary Body ◽  
Ex Vivo ◽  
Anterior Segment ◽  
Anterior Chamber Depth ◽  
Shear Wave Elastography ◽  
Ultrasound Elastography ◽  
Eye Model ◽  
Rabbit Eye

Introduction: A previous study has employed shear-wave ultrasound elastographic imaging to assess corneal rigidity in an ex-vivo porcine eye model. This study employs the same modality in vivo in a rabbit eye model in order to assess lens, ciliary body and total ocular rigidity changes following the instillation of atropine and pilocarpine. Methods: Ten non-pigmented female rabbits were examined. Measurements of the lens, ciliary body and total ocular rigidity as well as lens thickness and anterior chamber depth were taken with the Aixplorer system (SuperSonic Imagine, Aix-en-Provence, France) with the SuperLinear™ SL 15-4 transducer in both eyes at baseline as well as after pilocarpine and atropine instillation. The IOP was also measured with the TonoPen tonometer. Results: Changes in rigidity in the examined areas following atropine instillation were statistically not significant. Ciliary body rigidity was significantly increased whereas lens and total ocular rigidity were significantly reduced following pilocarpine instillation. The decrease in lens rigidity following pilocarpine was significantly associated with the respective increase in ciliary body rigidity. Conclusions: Shear-wave ultrasound elastography can detect in vivo rigidity changes in the anterior segment of the rabbit eye model and may potentially be applied in human eyes, providing useful clinical information on conditions in which rigidity changes play an important role, such as glaucoma, pseudoexfoliation syndrome or presbyopia.

scholarly journals In vivo assessment of spinal cord elasticity using shear wave ultrasound in dogs

2018 ◽  
Vol 29 (4) ◽  
pp. 461-469 ◽  
Author(s):  
Amro Al-Habib ◽  
Abdulrahman Albakr ◽  
Abdullah Al Towim ◽  
Metab Alkubeyyer ◽  
Abdullah Abu Jamea ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Shear Wave ◽  
Dura Mater ◽  
Ex Vivo ◽  
Shear Wave Elastography ◽  
Biomechanical Properties ◽  
Tissue Elasticity ◽  
Pia Mater ◽  
Balloon Compression

OBJECTIVEEvaluation of living tissue elasticity has wide applications in disease characterization and prognosis prediction. Few previous ex vivo attempts have been made to characterize spinal cord elasticity (SCE). Recently, tissue elasticity assessment has been clinically feasible using ultrasound shear wave elastography (SWE). The current study aims to characterize SCE in healthy dogs, in vivo, utilizing SWE, and to address SCE changes during compression.METHODSTen Greyhound dogs (mean age 14 months; mean weight 14.3 kg) were anesthetized and tracheally intubated, with hemodynamic and neurological monitoring. A 3-level, midcervical laminectomy was performed. SCE was assessed at baseline. Next, 8- and 13-mm balloon compressions were sequentially applied ventral to the spinal cord.RESULTSThe mean SCE was 18.5 ± 7 kPa. Elasticity of the central canal, pia mater, and dura mater were 21.7 ± 9.6 kPa, 26.1 ± 14.8 kPa, and 63.2 ± 11.5 kPa, respectively. As expected, the spinal cord demonstrated less elasticity than the dura mater (p < 0.0001) and pia mater (trend toward significance p = 0.08). Notably, the 13-mm balloon compression resulted in a stiffer spinal cord than at baseline (233 ± 73 kPa versus 18.5 ± 7 kPa, p < 0.0001) and 8-mm balloon compression (233 ± 73 kPa versus 185 ± 68 kPa, p < 0.048).CONCLUSIONSIn vivo SCE evaluation using SWE is feasible and comparable to earlier reports, as demonstrated by physical sectioning of the spinal cord. The compressed spinal cord is stiffer than a free spinal cord, with a linear increase in SCE with increasing mechanical compression. Knowledge of the biomechanical properties of the spinal cord including SCE has potential implications for disease management and prognosis.

Characterization of Passive Elastic Properties of the Human Tibialis Anterior Muscle Using Supersonic Shear Wave Elastography

2013 ◽  
Author(s):  
Terry K. Koo ◽  
Jingyi Guo ◽  
Jeffrey H. Cohen ◽  
Kevin J. Parker
Keyword(s):  
Shear Wave ◽  
Elastic Properties ◽  
Tibialis Anterior ◽  
Ex Vivo ◽  
Tibialis Anterior Muscle ◽  
Shear Wave Elastography ◽  
Indirect Measurement ◽  
Muscle Elasticity ◽  
Passive Muscle

In a companion ex vivo study of chicken muscles [1], we demonstrated that muscle elasticity measured by Supersonic shear wave elastography (SWE) increases linearly with passive tension, and hence, SWE could be an indirect measurement of passive muscle force. Objectives of the present study were: (1) Determine the test-retest reliability of SWE for in vivo measurements of passive muscle elasticity of the tibialis anterior (TA) muscle; (2) Assess the relationship between elasticity and ankle angle of the TA; and (3) Extract physiologically meaningful parameters from the elasticity-angle curves for better quantification of passive elastic properties.

scholarly journals Reverberant Shear Wave Elastography: A Multi-Modal and Multi-Scale Approach to Measure the Viscoelasticity Properties of Soft Tissues

2021 ◽  
Vol 8 ◽  
Author(s):  
Juvenal Ormachea ◽  
Fernando Zvietcovich
Keyword(s):  
Wave Propagation ◽  
Shear Wave ◽  
Acoustic Waves ◽  
Guided Waves ◽  
Soft Tissues ◽  
Ex Vivo ◽  
Surface Acoustic Waves ◽  
Shear Wave Elastography ◽  
Biomechanical Properties

There are a variety of approaches used to create elastography images. Techniques based on shear wave propagation have received significant attention. However, there remain some limitations and problems due to shear wave reflections, limited penetration in highly viscous media, requirements for prior knowledge of wave propagation direction, and complicated propagation in layers where surface acoustic waves and guided waves are dominant. To overcome these issues, reverberant shear wave elastography (RSWE) was proposed as an alternative method which applies the concept of a narrow-band diffuse field of shear waves within the tissue. Since 2017, the RSWE approach has been implemented in ultrasound (US) and optical coherence tomography (OCT). Specifically, this approach has been implemented in these imaging modalities because they are similar in image formation principles and both share several approaches to estimate the biomechanical properties in tissues. Moreover, they cover different spatial-scale and penetration depth characteristics. RSWE has shown promising results in the elastic and viscoelastic characterization of multiple tissues including liver, cornea, and breast. This review summarizes the 4-year progress of the RSWE method in US and OCT. Theoretical derivations, numerical simulations, and applications in ex vivo and in vivo tissues are shown. Finally, we emphasize the current challenges of RSWE in terms of excitation methods and estimation of biomechanical parameters for tissue-specific cases and discuss future pathways for the in vivo and in situ clinical implementations.

Evaluation of the Effect of Tissue Compression on the Results of Shear Wave Elastography Measurements

2018 ◽  
Vol 40 (6) ◽  
pp. 380-393 ◽  
Author(s):  
Jaromir Vachutka ◽  
Zuzana Sedlackova ◽  
Tomas Furst ◽  
Miroslav Herman ◽  
Jan Herman ◽  
...  
Keyword(s):  
Young’S Modulus ◽  
Shear Wave ◽  
Ex Vivo ◽  
Young's Modulus ◽  
Shear Wave Elastography ◽  
Shear Wave Imaging ◽  
Phantom Measurements ◽  
Wave Imaging ◽  
Tissue Compression

Shear wave imaging is considered to be more precise and less operator dependent when compared with strain imaging. It enables quantitative and reproducible data (Young’s modulus of the imaged tissue). However, results of shear wave imaging can be affected by a variety of different factors. The aim of this study is to evaluate the effect of the pressure applied by the ultrasound probe during examination on the measured values of Young’s modulus. The effect of the tissue compression on the results of the real-time shear wave elastography was evaluated via the gelatine phantom measurements, via the ex vivo experiments with pig liver, and via the in vivo measurements of the thyroid gland stiffness on healthy volunteers. The results of our measurements confirmed that the measured value of Young’s modulus increases with the increasing pressure applied on the imaged object. The highest increase was observed during the ex vivo experiments (400%), and the lowest increase was detected in the case of the phantom measurements (8%). A two- to threefold increase in Young’s modulus was observed between the minimum and maximum pressure in the case of the in vivo elastography measurements of thyroid gland. The Veronda-Westman theoretical model was used for the description of the tissue nonlinearity. We conclude that tissue compression by the force exerted on the probe can significantly affect the results of the real-time shear wave elastography measurements. Minimum pressure should be used when measuring the absolute value of Young’s modulus of superficial organs.

scholarly journals Viscoelasticity measured by shear wave elastography in a rat model of NAFLD: comparison with dynamic mechanical analysis

2020 ◽  
Author(s):  
Zhaoke Pi ◽  
Mengke Wang ◽  
Haoming Lin ◽  
Yanrong Guo ◽  
Siping Chen ◽  
...  
Keyword(s):  
Dynamic Mechanical Analysis ◽  
Shear Wave ◽  
Rat Model ◽  
Liver Steatosis ◽  
Shear Wave Elastography ◽  
Mechanical Analysis ◽  
Ultrasound Elastography ◽  
Nonalcoholic Fatty Liver ◽  
Dynamic Mechanical

Abstract Background: Nonalcoholic fatty liver disease (NAFLD) is rapidly becoming one of the most common liver diseases. Ultrasound elastography has been used for the diagnosis of NAFLD. However, clinical research on steatosis by elastography technology has mainly focused on steatosis with fibrosis or non-alcoholic steatohepatitis (NASH), while steatosis without fibrosis has been poorly studied. Moreover, the relationship between liver viscoelasticity and steatosis grade is not clear. In this study, we evaluated the degree of liver steatosis in a simple steatosis rat model using shear wave elastography (SWE). Results: The viscoelasticity values of 69 rats with hepatic steatosis were measured quantitatively by SWE in vivo and validated by a dynamic mechanical analysis (DMA) test. Pathological sections were used to determine the steatosis grading for each rat. The results showed that the elasticity values obtained by the two methods followed the same trend, and the elasticity is significantly correlated with liver steatosis. The Pearson’s correlation coefficients indicate that elasticity obtained by SWE is positively linear correlated with DMA (r = 0.628, p = 7.85×10 -9 ) Conclusion: SWE might have the feasibility to be introduced as an auxiliary technique for NAFLD patients in clinical settings. However, the viscosity results measured by the two methods are significantly different because the two methods work in different frequency bands.

scholarly journals Elastic Modulus and Elasticity Ratio of Malignant Breast Lesions with Shear Wave Ultrasound Elastography: Variations with Different Region of Interest and Lesion Size

Diagnostics ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1015
Author(s):  
Antonio Bulum ◽  
Gordana Ivanac ◽  
Eugen Divjak ◽  
Iva Biondić Špoljar ◽  
Martina Džoić Dominković ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Shear Wave ◽  
Large Diameter ◽  
Small Diameter ◽  
Shear Wave Elastography ◽  
Lesion Size ◽  
Ultrasound Elastography ◽  
Breast Lesions ◽  
Malignant Breast ◽  
The Impact

Shear wave elastography (SWE) is a type of ultrasound elastography with which the elastic properties of breast tissues can be quantitatively assessed. The purpose of this study was to determine the impact of different regions of interest (ROI) and lesion size on the performance of SWE in differentiating malignant breast lesions. The study included 150 female patients with histopathologically confirmed malignant breast lesions. Minimal (Emin), mean (Emean), maximal (Emax) elastic modulus and elasticity ratio (e-ratio) values were measured using a circular ROI size of 2, 4 and 6 mm diameters and the lesions were divided into large (diameter ≥ 15 mm) and small (diameter < 15 mm). Highest Emin, Emean and e-ratio values and lowest variability were observed when using the 2 mm ROI. Emax values did not differ between different ROI sizes. Larger lesions had significantly higher Emean and Emax values, but there was no difference in e-ratio values between lesions of different sizes. In conclusion, when measuring the Emin, Emean and e-ratio of malignant breast lesions using SWE the smallest possible ROI size should be used regardless of lesion size. ROI size has no impact on Emax values while lesion size has no impact on e-ratio values.

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