A system for imaging a vessel of a patient comprises an elongated sheath with proximal and distal ends. The elongated sheath includes a flexible body with a first lumen in communication with a distal opening at the distal end. The system further includes an imaging core disposed within the first lumen and rotatable about an axis of rotation. The imaging core includes a first transducer subassembly adapted to transmit a first beam, distally of the flexible body, through the distal opening. The imaging core also includes a second transducer subassembly adapted to transmit a second beam through the flexible body in a transverse direction to the axis of rotation.
