Devices and methods for obtaining a three-dimensional image of an internal body site are provided. The subject devices are elongated structures (e.g., catheters) having a plurality of ultrasonic transducers located at their distal end. The configuration of the plurality of ultrasonic transducers may be reversibly changed from a first to a second configuration, where the radial aperture of the plurality of ultrasonic transducers is greater in the second configuration than in the first configuration. A feature of certain embodiments of the subject invention is that the plurality of ultrasonic tranducers are configured in the second configuration as a substantially continuous set of transducers. In using the subject imaging devices, the distal end of the devices is positioned at the internal body site of interest while the plurality of ultrasonic transducers is in the first configuration. The configuration of the ultrasonic transducers in then changed to the second configuration for imaging the internal body site. The subject devices and methods for their use find application in imaging a variety of different internal body sites.