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Specular Reflector Noise: Effect and Correction for in Vivo Attenuation Estimation

After reviewing the usual models proposed for the echo-graphic response of soft tissues, we discuss the interaction between the ultrasonic wave and large size obstacles. Structures of this size, specular reflectors, can be found in tissues. The influence of such reflectors on in vivo attenuation measurements is detailed. We point out the importance of the specular echo noise originating from two kinds of reflectors: planelike and vessel-like reflectors. We present a complete study of their influence on two different algorithms for attenuation estimates: the spectral centroid shift and the narrow band methods. Results are presented on stimulated data, a tissue-mimicking phantom and in vivo muscle data. Different procedures for minimizing the specular echo noise are also discussed.