Intravascular systems, devices, and methods having a captively-held filling are provided. An intravascular imaging device can include a flexible elongate member including a lumen having a proximal portion and a distal portion a drive cable disposed within the lumen such that an ultrasound transducer coupled to the drive cable is positioned within the distal portion of the lumen and a filling captively held within at least the distal portion of the lumen and surrounding the ultrasound transducer, the filling facilitating transmission and receipt of ultrasound signals. A method of manufacturing an intravascular imaging device can include acquiring a flexible elongate member including a lumen inserting a drive cable into the lumen, a rotational ultrasound transducer being coupled to the drive cable inserting a filling that facilitates transmission and receipt of ultrasonic signals into the lumen such that the filling surrounds rotational ultrasound transducer and sealing the filling within the lumen.
