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1

Effects of vibration and passive resting on muscle stiffness and restitution after submaximal exercise analyzed by elastography

Chwała Wiesław, Pogwizd Paweł

Acta of Bioengineering and Biomechanics

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2021

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Vol. 23, no. 2

3--11

EN

Purpose: The research aimed to assess the influence of vibration therapy on acceleration of muscles regeneration process after physical effort. Verification of the pace of motor capabilities recovery in fatigued muscles was performed with the use of the measurement method applying shear-wave elastography. It took into account an alteration in muscle stiffness affected by created passive stresses and accompanying deformations connected with muscles work above their resting length. Methods: The research included 42 young males aged 20–24. They all were a homogeneous group regarding body build indices (body height 175.4 ± 8.1 cm; body mass 75.5 ± 8.32 kg) and the level of physical activity. Muscles of lower limbs (hip and knee joints extensors and flexors plantaris) were subject to submaximal exercise of the auxotonic muscle work character after a 90 s warm-up. The exercise comprised 20-fold overcoming the load at the level of 75% of maximal strength abilities without rest, by alternating between extension and flexion of lower limbs joints at the leg press placed at 45° angle upward and monitoring of angle setting of lower limbs joints. The post-exercise restitution used a vibration stimulus of variable frequency ranging from 20 to 50 Hz and amplitude of 0.5 mm, and passive resting in the control group. For an objective assessment of the applied vibration effect, a 5-fold measurement of rectus femoris muscles stiffness of both limbs at the middle of venter took place after each stage of the experiment. Results: After warm-up, a considerable increase of the examined muscles stiffness, that did not vary significantly, was observed. In the DW experimental group (vibration massage), where post-exercise restitution was enhanced by vibration, significantly lower values of muscle stiffness were registered after each of the post-exercise regeneration stages in relation to the DB control group (passive rest). After the I regeneration stage, a value of the Δ σ _r1-s variable ( p < 0.05) lower by 16% was noticed in favour of the group enhanced by vibration. Whereas, values of muscles stiffness after the II stage of regeneration, Δ σ _r2-s were by 14% lower in favour of DW group ( p < 0.005). Conclusions: Enhancement of the post-exercise relaxation of muscles by vibration treatment significantly lowered the values of post-exercise muscles stiffness and turned out to be a more effective method of restitution than passive resting. Recovery of the level of muscles stiffness from before the exercise was much slower in the control group than in the one enhanced by vibration. The improved method of muscle stiffness measurement with the use of shear-wave elastography with a special head attachment turned out to be a useful tool to assess post-exercise muscles restitution.

2

Badania ultrasonograficzne: elastografia ultrasonograficzna

Fedak Andrzej

Inżynier i Fizyk Medyczny

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2019

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Vol. 8, nr 3

167--170

PL

Badania ultrasonograficzne z wykorzystaniem zjawiska propagacji fali ścinającej w ośrodkach o różnej impedancji akustycznej – oporności tkanek w czasie przechodzenia przez nie fali mechanicznej – ultradźwiękowej, są w stanie wykazać metodami obrazowymi obecność zmian, które mogą być stwierdzone jedynie w badaniach histopatologicznych. Autor przedstawia podstawy fizyczne, mechanizmy obrazowania oraz podstawowe zastosowania metody.

EN

Ultrasound examinations, using the shear wave propagation phenomenon in medium with different acoustic impedance – tissue resistance during the passing of a mechanical wave – ultrasound wave, are able to show, by means of imaging methods, the presence of changes that can be found only in histopathological studies. The author presents physical fundamentals, imaging mechanisms and basic applications of the modern ultrasound examination method.

3

Introduction to tissue shear wave elastography

Nowicki A., Dobruch-Sobczak K.

Hydroacoustics

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2017

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Vol. 20

129--138

EN

Ultrasonic elastography is a technique allowing imaging of the elastic properties of tissue. There are two basic techniques of elastographic imaging; compressional - displaying the evaluation of tissue deformation under the external stress; and dynamic, tracking the propagation velocity of the shear wave generated by the acoustic radiation force. Soft tissue bulk modulus varies, from a few to several GPa, whereas the shear modulus is significantly smaller, not exceeding a few hundred Pa for adipose tissue, breast or liver, up to several hundred kPa for “hard” tissue. Forces generated in the tissue due to the external, axial piston-like stresses depend mainly on the shear modulus. In Shear Wave Elastography, long, several tens of microseconds, ultrasonic pulses successively focused at several depths are sent: generating a conical wave front moving with the supersonic velocity, depending on the tissue stiffness. Velocity of propagation of shear wave depends on the shear modulus μ and the modulus of elasticity E of the examined tissue is equal to E=3μ.

4

Normalization of Multifocal Acoustic Radiation Force Impulse Images

González-Salido N., Camacho J.

Archives of Acoustics

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2017

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Vol. 42, No. 2

321--331

EN

Imaging the tissue displacements caused by Acoustic Radiation Force Impulse (ARFI) provides qualitative tissue elasticity maps around the focus. To increase imaging range, multi-focus techniques combine several images obtained with different focal depths. Since the acoustic radiation force depends on focus depth, axial distance and steering angle, a normalization process is required before blending multi-focal ARFI images so that changes in the displayed displacements represent true tissue elasticity variations. This work analyzes the sources of displacement variability in multi-focal-zone ARFI and proposes a procedure to normalize and combine partial images. The proposal is based on the system focal configuration, transducer characteristics and global tissue parameters found by ultrasonic measurements. Performance of the proposed algorithm is experimentally evaluated with tissue mimicking phantoms.

5

Relationships between acoustical properties and stiffness of soft tissue phantoms

Gambin B., Kruglenko E., Byra M.

Hydroacoustics

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2016

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Vol. 19

111--120

EN

Polyvinyl-alcohol cryogel is commonly used for soft tissue phantom manufacture. The gel formation from an aqueous solution of polyvinyl-alcohol takes place during the freezing and thawing cycle. The aim of this work was to assess the degree of gel solidification, hence the material stiffness, by means of quantitative ultrasound. We manufactured three phantoms which differed in the number of freezing/thawing cycles. First, tissue phantoms were examined with an elastography technique. Next, we measured the speed of sound and the attenuation coefficient. What is more, the inter structure variations in phantoms were assessed with the Nakagami imaging which quantifies the scattering properties of the backscattered ultrasound echo. Obtained results confirmed the connection between the number of freezing/thawing cycles and the solidification p rocess. We d efined th e bo undary layer as a region which has a different structure than the sample interior. Next, for each phantom this layer was extracted based on a Nakagami parameter map. We calculated that the thickness of the boundary layer was lower in samples which were subjected to a larger number of freezing/thawing cycles.

6

Automatic seed point selection in ultrasound echography images of breast using texture features

Selvan S., Shenbaga Devi S.

Biocybernetics and Biomedical Engineering

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2015

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Vol. 35, no. 3

157--168

EN

Automatic segmentation of breast lesions in 2D ultrasound B-scan images via active contours, require a seed point to be selected inside the breast lesion. The grey levels on an ultrasound image of the breast show intensity information. The fat tissue is hypo echoic relative to the surrounding glandular tissue. The glandular parenchyma tissue usually appears homogeneously echogenic as compared with fat lobules. Simple cysts are anechoic. Malignant solid masses are usually heterogeneous, hypo echoic and tend to look intensely black compared to surrounding isoechoic fat. Benign solid masses tend to appear on ultrasound with intense and uniform hyper echogenicity. Texture features represent changes in grey level intensities. This paper proposes a method that can automatically identify a seed point based on texture features and allow automatic contour initialization for level set segmentation. This seed point plotted on an US B-scan image is mapped on to its corresponding elastogram pair. The proposed approach is applied to 199 ultrasound B-scan images of which 52 are benign solid masses, 84 malignant solid masses and 63 simple and complex cysts. The seed point obtained using this approach is mapped to its corresponding elastogram pair in 62 US B-scan and US elastography image pairs. Quantitative experiment results show that our proposed approach can successfully find proper seed points based on texture values, in ultrasound B-scan images and therefore in elastography images, with an overall accuracy of 86.93%. This approach is effective and makes segmentation of breast lesions computationally easier, more accurate and fast.

7

Ultrasonografia nadnerczy – stan obecny

Słapa R., Kasperlik-Załuska A., Piwoński A., Bednarczuk T., Rosłonowska E., Szopiński K., Jakubowski W.

Acta Bio-Optica et Informatica Medica. Inżynieria Biomedyczna

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2011

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Vol. 17, nr 1

58-61

PL

W pracy przedstawiono stan obecny dotyczący diagnostyki ultrasonograficznej nadnerczy, z uwzględnieniem nowych technik ultrasonograficznych, jak: ultrasonografia endoskopowa, elastografia dynamiczna, ultrasonografia 3D/4D, obrazowanie harmoniczne, ultrasonografia złożona przestrzennie oraz ultrasonograficzne środki kontrastujące.

EN

The paper presents contemporary adrenal ultrasound including new ultrasound techniques as endoscopic ultrasound, shear wave elastography, 3D/4D ultrasound, harmonic ultrasound, compound ultrasound and ultrasound contrast agents.

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Nowe techniki ultrasonograficzne w badaniach tarczycy

Słapa R., Jakubowski W.

Acta Bio-Optica et Informatica Medica. Inżynieria Biomedyczna

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2010

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Vol. 16, nr 2

147-150

PL

W artykule omówiono nowe techniki ultrasonograficzne znajdujące zastosowanie w rutynowych badaniach tarczycy oraz będące w fazie prób klinicznych. Nowe techniki ultrasonograficzne można podzielić na: polepszające jakość obrazu w prezentacji B (skali szarości), jak obrazowanie harmoniczne i ultrasonografia złożona; przekształcające badanie w przestrzeni, jak rozszerzone pole widzenia i ultrasonografia trójwymiarowa, oraz dostarczające jakościowo nowych informacji w badaniu ultrasonograficznym, jak mapowanie mikrozwapnień i elastografia.

EN

The new ultrasound techniques applied for routine examinations of thyroid gland, as well as introduced in clinical phase of research studies, were discussed. These can be divided into techniques that improve quality of the image in B mode (gray-scale) as harmonic imaging and compound ultrasound, the techniques transforming examination in space as extended field of view and three-dimensional ultrasound, and finally techniques delivering qualitatively new information in on ultrasound examination as mapping of microcalcifications and elastography.

9

Nieinwazyjna ocena struktury tkanek skóry oraz analiza składu ciała osób z rozpoznaniem zmian cellulitowych - analiza przypadku

Tomaszewicz V., Zalewski P., Klawe J., Tafil-Klawe M., Kołodziejska K., Cieściński J., Lasek W.

Acta Bio-Optica et Informatica Medica. Inżynieria Biomedyczna

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2010

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Vol. 16, nr 4

341-344

PL

Zmiany struktury skóry dotkniętej cellulitem są spowodowane wieloma czynnikami, m.in. zaburzeniami metabolizmu tkanki tłuszczowej, upośledzeniem przepływu krwi I limfy oraz magazynowaniem produktów przemiany mateiii w skórze. Problem cellulitu dotyczy wielu osób, w zdecydowanej większości kobiet. Wykorzystując nowoczesne metody analizy właściwości tnechanicznych skóry oraz analizy składu ciała, możliwa jest analiza wielu czynników wpływających na nasilenie procesu negatywnych zmian strukturalnych w obrębie skóry i tkanki podskórnej.

EN

Morphological changes of skin with ceilulite are caused by various factors, e.g. adipose tissue metabolism and microcirculation disorders. T h e y may also result from gathering of metabolism products witthin skin. Cellulite problems are considered to be a serious problem for women. This kind of sk n changes causes various problem in dermatological and psychological aspects of treatment. Modernand non-invasive examination techniques of skin propertis and body composition analysis enable to obtain very valuable data concerning ceilulite.

10

Study of displacement estimation methods for elastographic applications

Kałużyński K., Leśniak B., Cygan S.

Elektronika : konstrukcje, technologie, zastosowania

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2004

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Vol. 45, nr 8-9

135-138

EN

Two methods of displacement estimation - based on the 1D maximum crosscorrelation coefficient and on the minimum of the sum of absolute differences (SAD) were tested on the RF and baseband envelope data, obtained from a homogenous tissue phantom, submitted to a quasistatic deformation, uniform in the analysed area of size approx. 3 mm x 22 mm. The maximum strain ranged from 2.4% to 7.5%. The data processing consisted in choosing a 1D correlation/SAD kernel of length from 0.4 mm to approx. 1.5 mm, and comparing it within a search kernel ranging from approx. 0.7 mm to 1.8 mm. The displacement images were submitted to a 1D median filtering and to smoothing. The processing was carried out in the MATLAB environment. Use of the RF data appeared fundamental to obtain low variance displacement estimates. The best results were obtained using the SAD method.

PL

Badaniom poddano metodę estymacji przemieszczeń opartą na poszukiwaniu maksimum współczynnika korelacji 1D oraz metodę wykorzystującą minimum sumy różnic bezwzględnych SAD. Analizowano dane RF oraz dane w paśmie podstawowym, pochodzące z jednorodnego fantomu tkankowego poddanego jednorodnemu quasistatycznemu odkształceniu, dla obszaru o wymiarach ok. 3 mm x 22 mm. Maksymalne wartości odkształceń wynosiły 2.4% - 7.5%. Przetwarzanie polegało na porównywaniu jądra o długości od 0.4 mm do 1.5 mm z obszarem poszukiwań o wymiarach od 0.7 mm do 1.8 mm. Obrazy przemieszczeń poddano filtracji medianowej i wygładzaniu. Przetwarzanie przeprowadzono w środowisku MATLAB. Estymację przemieszczeń o najniższej wariancji zapewnia wykorzystanie danych RF oraz metody SAD.