Gallstones: in vitro comparison of physical, radiographic, and ultrasonic characteristics.

An in vitro study of 30 gallstones was undertaken in which radiographic, ultrasonic, and physical characteristics were compared. Stones greater than 1 mm in diameter were consistently visualized in vitro using higher frequency transducers, lower intensities, and simple sector scanning techniques in different planes. All stones greater than 3 mm demonstrated consistent posterior acoustic shadowing, similarly facilitated by use of these techniques. The demonstration of posterior acoustic shadowing does not relate to the calcium content, shape, surface characteristics, or specific gravity of the stone.