The bony labyrinth obtained at necropsy in four cases was studied by a new computer-generated three-dimensional (3-D) system. One case was normal (control) and the other three were histopathologically confirmed cases of Mondini's dysplasia. In case 1, the cochlea had only 2 turns and the lateral semicircular canal did not make a circle but appeared as a spherical mass projecting from the utricle even though the posterior semicircular canal made a normal circle. In case 2, there were no turns in the cochlea even though the semicircular canals and the vestibule appeared normal. In case 3, the cochlea showed 1 to 1 and 1/2 turns and the semicircular canals were premature showing only bud-like projections. This 3-D imaging system, which utilizes the toggling method, provides a way of obtaining satisfactory images without markers, and the time required to obtain these 3-D images was reduced by using a video camera instead of a digitizer. One of the problems associated with the use of 3-D imaging is the long processing time. We resolved this by inputting the section images with a video camera and by picking up structures using density segmentation instead of tracing with a digitizer.</p
