Pseudoenhancement of Gallbladder Sludge: A Confusing Artifact Caused by Nonlinear Propagation of Ultrasound Through Microbubbles - Li, S. Y.; Huang, P.; Cosgrove, D.; Xu, H.; Xu, L. L.; Liang, X.; Cai, X. J. (Ultraschall in der Medizin - European Journal of Ultrasound, 2016)