Electronic work stations are becoming a standard means of presenting medical images for diagnosis and consultation, and they will become more wide-spread as picture archiving and communication systems (PACS) come into use. These work stations must allow the user both to perceive the patterns necessary for accurate diagnosis and to "navigate" efficiently within large sets of related images, ie, quickly find and compare desired images. The work stations must operate without a feeling of "fraction" and have an affordable cost. In this report we survey the tasks and system objectives, first regarding the perceptual needs and second with respect to the navigational needs. We then survey the technology available to satisfy these needs and conclude with a list of needed research and technology that can be expected or should be provided in the future.