A registration apparatus registers an elongated introduction element (18), like a catheter or a needle, during an interventional procedure, for instance, a brachytherapy or a biopsy. A guide element (13) includes at least one opening which guides the introduction element when being introduced into a living being (2) through the opening. A temperature profile generation element (14) associated with the opening generates a characteristic temperature profile at the opening for being transferred to the introduction element when being present in the opening. A temperature determination unit (15) determines a temperature along the introduction element, and a registration unit (16) registers the introduction element. The registering includes identifying the transferred characteristic temperature profile on the introduction element based on the determined temperature. This allows the registration unit to register the introduction element during the introduction process in a simple and efficient manner.