However, rather than providing the tubular member 132 with necked down portions 132a, 132b and 132c, in the embodiment shown in FIG. 12 radiopaque bands 162 formed of a suitable material such as platinum are disposed within the passageway 133 and are secured to the interior wall forming the passageway 133 of the flexible elongate tubular member 132 in spaced apart positions corresponding to the po