Nonlinear tissue mimicking phantoms characterization using the Nakagami statistical model: simulations and measurements

International audienceIn order to improve the tissue characterization, the probability density function of ultrasonic backscattered echoes which may be treated as random signals, is modeled by using Nakagami statistical distribution. Recently, it has been found that Nakagami statistical model constitutes a quite good model in tissue characterization due to its simplicity and general character. In the present study, computer simulations and experiments on phantoms have been carried out to test the validity of Nakagami distribution in order to model the backscattered envelope of ultrasonic signals in the nonlinear regime. Experiments were performed using a 5MHz linear array connected to an open research platform. A commercially available phantom was used to mimick tissue backscatter. For different sizes and positions of the sampling window, the RF signals have been acquired at different frequencies and bandwidths, then filtered around the center frequency and around twice the center frequency. The signals obtained have been analyzed in order to evaluate the Nakagami parameter (m), the scaling parameter (Ω) and the probability density function. These results have been compared to those obtained by using Field II software

Transmission d'ondes acoustiques ultrasonores par effet tunnel dans un guide d'onde à section variable

Des résultats expérimentaux et numériques concernant la propagation d'ondes de Lamb dans un guide d'onde élastique de section linéairement variable entre deux tronçons d'épaisseurs constantes de 2 et 5 mm sont présentés. Dans les conditions où l'onde de Lamb atteint sa fréquence de coupure, lors de la propagation à partir du tronçon le plus épais, elle est réfléchie mais une partie de l'onde est transmise par effet tunnel dans le tronçon de plus faible épaisseur, avec une conversion de modes

The Parametric Images of Microbubbles and Tissue Mimicking Phantoms Based on the Nakagami Parameters Map

AbstractThe ultrasonic B-mode imaging is an important clinical tool used to examine internal structures of biological tissue and contrast microbubbles. To overcome the drawbacks of conventional B-scans which cannot fully reflect the nature of the tissue, other imaging methods based on stochastic models are proposed. Among these models, the Nakagami statistical model was chosen, because it is more general and simpler to apply than other statistical models (Rayleigh and K models), to generate parametric images based on the Nakagami parameters.Experiments were performed using a 2.5MHz linear array connected to an open research platform. A commercially phantom was used to mimic tissue and microbubbles backscatters. For several regions of interest and for different microbubbles dilutions, the RF signals have been generated at 3 and 5 transmit cycles.The Nakagami image can be combined with the use of the B-mode image simultaneously to visualize the tissue and the contrast microbubbles structures for a better medical diagnosis

Propagation of Lamb waves in an immersed periodically grooved plate: Experimental detection of the scattered converted backward waves

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