A delivery apparatus for the percutaneous placement of a medical device at an area of interest in a tissue mass comprises an introducer comprising a cannula having an insertion tip, an expulsion opening near the insertion tip, and a medical device within the cannula comprising an imaging element, and a guide element connected to the imaging element and having a separable portion, and wherein the cannula is inserted into the tissue mass such that the medical device can be expelled through the expulsion opening into the tissue mass, and when the cannula is withdrawn from the tissue mass, the imaging element is placed within the tissue mass at the area of interest, and at least part of the guide element extends exteriorly of the tissue mass, and when the separable portion is separated from the guide element, no part of the guide element extends exteriorly of the tissue mass.