An ultrasound imaging system is disclosed. The system comprises an ultrasound emitter and receiver movably disposed within an elongate member, an actuator coupled to the emitter, and a control system. The actuator moves the emitter through a path comprising at least a portion of an arc. The control system controls the emission of a sequence of pulses from the emitter and receives from the receiver ultrasound echo data associated with the sequence of pulses emitted along the path. The control system processes the ultrasound echo data to generate a cross-sectional image of an internal structure based on echo amplitude data and echo velocity data.
