Shannon entropy: A specular echo-insensitive imaging metric showing myocardial anisotropy

Abstract

This work demonstrates the utility of Shannon entropy imaging of myocardial anisotropy in mice. Conventional acoustic microscopy measurements of excised short-axis myocardial slices may be used to delineate this anisotropy ex vivo. This approach often requires processing of specular echoes, which can cause artifacts in images that obscure detailed structures near interfacial boundaries. Two different ultrasonic signal receivers were evaluated using the same raw data as input: log energy (log[E <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</sub> ]) and Shannon entropy imaging (H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</sub> ), entropic imaging is least influenced by specular echoes and is able to resolve anisotropy near interfacial boundaries.