Analysis of image vs. position, scale and direction reveals pattern texture anisotropy

Lehoucq, Roland; Weiss, JÃ©rÃ ́me; Dubrulle, BÃ©rengÃ ̈re; Amon, Axelle; Bouil, Antoine Le; Crassous, JÃ©rÃ ́me; Amitrano, David; Graner, F.

doi:10.3389/fphy.2014.00084

Cited by 15 publications

(8 citation statements)

References 31 publications

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“…To characterize the degree of anisotropy in an image we use a method extensively described elsewhere [24]. Considering the value of each pixel of an activity image as a weight, we compute the center of mass of the image G and the inertia tensor P which quantify the spatial repartition of the weights around G (see Fig.…”

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confidence: 99%

Experimental study of shear band formation: Bifurcation and localization

Nguyen¹,

Amon²

2016

EPL

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-We report the experimental observation of the bifurcation at the origin of localization of the deformation in a granular material submitted to uniaxial compression. We present a quantitative characterization of the heterogeneity in the strain field repartition allowing to evidence objectively the existence of a bifurcation initiating the shear bands formation process. We show that this bifurcation is supercritical and has no clear signature on the stress-strain curve. At the bifurcation, a symetry breaking occurs characterized by the emergence of a well-defined orientation corresponding to the Mohr-Coulomb angle. Yet, plasticity is still diffuse and the shear band extension is of the order of the sample width. While loading proceeds, the shear band narrows until it reaches, after the peak of the stress-strain curve, a stationary width.

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confidence: 99%

Experimental study of shear band formation: Bifurcation and localization

Nguyen¹,

Amon²

2016

EPL

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“…We have developed different image analysis tools [17,20,21] in order to characterize quantitatively the process of formation of the shear band. We present here only the results obtained using projection analysis.…”

Section: Image Analysis Methodsmentioning

confidence: 99%

Experimental study of shear bands formation in a granular material

et al. 2017

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Abstract. We present an experimental investigation of the formation of shear bands in a granular sample submitted to a biaxial test. Our principal result is the direct observation of the bifurcation at the origin of the localization process in the material. At the bifurcation, the shear band is spatially extended: we observe a breaking of symmetry without any sudden localization of the deformation in a narrow band. Our work thus allows to clearly distinguish different phenomena: bifurcation which is a ponctual event which occurs before the peak, localization which is a process that covers a range of deformation of several percents during which the peak occurs and finally stationary shear bands which are well-defined permanent structures that can be observed at the end of the localization process, after the peak.

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“…As degenerative muscle changes intensify (i.e., increase fat content and fibrosis), this preferential orientation of the signal may be disrupted; that is, the local texture anisotropy is reduced. A proposed method for quantitatively revealing and characterizing local texture anisotropy consists of dividing the image into analysis boxes; in each box, an ellipse (the inertia tensor) is fitted to the signal and determines the direction in which the signal is more present (Lehoucq et al 2015). To the best of our knowledge, no previous report has investigated the potential of local texture anisotropy as an estimate of muscle quality.…”

Section: Introductionmentioning

confidence: 99%

Local Texture Anisotropy as an Estimate of Muscle Quality in Ultrasound Imaging

Dubois

Bachasson

Lacourpaille

et al. 2018

Ultrasound in Medicine & Biology

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This study introduces local pattern texture anisotropy as a novel parameter to differentiate healthy and disordered muscle and to gauge the severity of muscle impairments based on B-mode ultrasound images. Preliminary human results are also presented. A local pattern texture anisotropy index (TAI) was computed in one region of interest in the short head of the biceps brachii. The effects of gain settings and box sizes required for TAI computation were investigated. Between-day reliability was studied in patients with sporadic inclusion body myositis (n = 26). The ability of the TAI to discriminate dystrophic from healthy muscle was evaluated in patients with Duchenne muscular dystrophy and healthy controls (n = 16). TAI values were compared with a gray-scale index (GSI). TAI values were less influenced by gain settings than were GSI values. TAI had lower between-day variability (typical error = 2.3%) compared with GSI (typical error = 2.3% vs. 8.3%, respectively). Patients with Duchenne muscular dystrophy had lower TAIs than controls (0.76 ± 0.06 vs. 0.87 ± 0.03, respectively, p <0.05). At 40% gain, TAI values correlated with percentage predicted elbow flexor strength in inclusion body myositis (R = 0.63, p <0.001). The TAI may be a promising addition to other texture-based approaches for quantitative muscle ultrasound imaging.

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Analysis of image vs. position, scale and direction reveals pattern texture anisotropy

Cited by 15 publications

References 31 publications

Experimental study of shear band formation: Bifurcation and localization

Experimental study of shear band formation: Bifurcation and localization

Experimental study of shear bands formation in a granular material

Local Texture Anisotropy as an Estimate of Muscle Quality in Ultrasound Imaging

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