A tissue-removing catheter for removing tissue in a body lumen includes an elongate body having an axis and proximal and distal end portions spaced apart from one another along the axis. A handle is mounted to the proximal end portion of the elongate body and operable to cause rotation of the elongate body. A tissue-removing element is mounted on the elongate body. The tissue-removing element is configured to remove the tissue as the tissue-removing element is rotated by the elongate body within the body lumen. An inner liner is received within the elongate body and is coupled to the handle at a proximal end portion of the inner liner. The inner liner defines a guidewire lumen. A sensor is arranged with respect to the inner liner and is configured to produce a signal for indicating the presence of a guidewire within the inner liner.
