An expandable member for characterizing a three-dimensional space within a mammalian body is described. The expandable member is delivered to a target region in a deflated state where it is expanded by inflation of the member. Sensory transducers that contact the member relay sensory information generated when the member is in an expanded state to a microprocessor located outside the body. Using the sensory information, a data-driven picture that characterizes the three-dimensional space within the body is created with a microprocessor. The apparatus is useful in preparation for minimally invasive surgical therapy.
