An atherectomy catheter is provided having a tissue collection chamber capable of being cleaned out in a simple, fast and effective way, and also provides methods of using said catheter to remove material from a blood vessel lumen. In one embodiment the tissue collection chamber has an expandable tip having a first closed position capable of retaining material in the chamber and having a second open position that may allow expulsion of material from the chamber. In a second embodiment the tissue collection chamber has a displaceable tip having a first closed position to retain material in the chamber and having a second open position to allow expulsion of material from the chamber.