Disclosed are vascular access devices, implantable dialysis grafts, and systems that include them useful in facilitating easy, accurate and reproducible cannulation or needle entry into an implantable device such as a hemodialysis graft, by localizing a portion of the implanted graft that contains one or more paramagnetic materials that operably define the physical boundaries of the target cannulation site/entry port by passage of an external magnetic detector wand over that portion of the patients body into which the device has been implanted.
