A detection and guide system provides access to desired blood vessel locations. An implant formed of a biocompatible material is implanted within a mammalian body proximate an outer surface of a blood vessel. The detection and guide system may be configured to be positioned outside the mammalian body to detect the implant and to guide a needle to the desired entry site of the biological boundary structure. A needle guide may be coupled to a housing of the detection and guide system and directed at an angle such that positioning the implant detector over the implant aligns an opening through the needle guide with the desired entry site. The detection and guide system may, for example, provide metal detection of a metallic implant or magnetic detection of a magnetic implant.
