The International Symposium of Acoustical Imaging has been widely recognized as the premier forum for presentations of advanced research result in both theoretical and experimental development. Held regularly since 1968, the symposium brings together international leading researchers in the area of acoustical imaging. The proceedings from the 25th meeting contains articles on the following topics: Mathematics and Physics of Acoustical Imaging, Transducers and Arrays, Nondestructive Evaluation, Geophysical and Underwater Ultrasonics, Microscopy and Microscanning, Scattering by Blood and Tissue, Medical and Biological Image Formation, Tissue Characterization, Tissue and Motion and Blood Flow, Elasticity Imaging, Hard Tissues, and Novel and Emerging Methods.