The dendrimer conjugates may include an imaging agent, which permits the lymphatic system to be imaged when selective intra-lymphatic concentration of the dendrimer occurs. Further, when the dendrimer conjugate includes an activatable anti-tumor agent, the method may include selectively applying physical energy to the subject’s body to selectively activate the anti-tumor agent in the lymphatic system. The dendrimer conjugate can include gadolinium, wherein the gadolinium acts as a contrast agent to image the lymphatic system.

In a particular example, the dendrimer conjugate includes a gadolinium-imaging agent that is activatable by a neutron beam. Once the gadolinium containing dendrimer conjugate is concentrated in the lymphatic system, detecting selective concentration of the dendrimer conjugate in the lymphatic system images the lymphatic system. The presence of tumor in lymph nodes can also be detecting using this imaging technique. A neutron beam is then selectively applied to the imaged lymphatic system to selectively activate the anti-tumor agent at target areas in the lymphatic system for the treatment of metastatic tumor. In this example, the target area may be a lymph node, such as a sentinel lymph node, or a lymphatic vessel. The target area, when imaged, may show evidence of primary or metastatic tumor.