formed by the coils the hollow interior and the air pockets of the coil spring 62 as well as the radiopaque fibers 64 the coil spring 62 is pre shaped prior to being loaded into the marker recess 46 so that it tends to form a circular shape as shown in fig6 after it is ejected from the marker recess 46 the circular shape tends to resist migration within the tissue fig7 illustrates a second embodiment 70 of a radiopaque marker having a star burst configuration comprising a core 72 with multiple fingers 74 extending from the core fig8 illustrates a third embodiment 80 of a radiopaque marker that is similar to the star burst marker 70 in that it comprises a core 82 from which extend three fingers 84 each of the fingers includes radiopaque fibers 86 which are preferably made from dacron or a similar material fig9 illustrates a fourth embodiment 90 of a radiopaque marker having a generally y shaped configuration comprising an arm 92 from which extend diverging fingers 94 the arm and fingers 92 94 are preferably made from a suitable resilient metal such that the fingers can be compressed towards each other and the entire radiopaque marker 90 stored within the marker recess 46 of the cannula upon ejection of the marker 90 from the marker recess 46 into the tissue mass the fingers 94 will spring outwardly to provide the marker 90 with an effectively greater.