A method for mapping a lymphatic system following a cavity generating procedure, may include a step of providing a post-biopsy cavity treatment implant, the implant including a collagenous matrix having a non-uniform cross-linking density that is configured to cause the implant to swell non-uniformly when placed within an aqueous environment, the implant including a dye or a pigment contained therein. The provided post-biopsy cavity treatment implant may then be implanted into the cavity and the cavity closed. The dye/pigment may then be caused to be released from the implant and to propagate through the lymphatic system. The propagated dye/pigment may then be visualized in the lymphatic system using a selected visualization mode.