Novel technique changes lymph node biopsy, reduces radiatio...(o the sound. Exogenous contrast a...)

Exogenous contrast agents, like the gold nanocages developed by Xia's group, can be used to image parts of the body that even contain endogenous contrast agents. These nanocages are especially attractive because their properties can be tuned to give optimal contrast and gold is non-toxic.

"By controlling the synthesis, we can move the absorption peak for the nanocages to a region that allows them to be imaged deep in tissue. We can also attach biomolecules to the surface of the nanocages so they are targeted to cancer cells," Xia said.

The SLN, the first draining node, is often biopsied in breast cancer patients to determine if the cancer has metastasized. "To find the SLN, doctors inject radioactive particles and a blue dye into the breast. The lymphatic system gobbles up the injected material, treating it as foreign matter and accumulating it in the SLN. The radioactive particles can be detected using a Geiger counter held to the breast to locate the lymph nodes. Then, the doctors surgically open the breast, follow the blue dye, and dissect the SLN," Wang said.

Wang and Xia's technique allows the SLN to be imaged safely without radioactivity or surgery. A piece of tissue can then be removed using a minimally invasive needle biopsy and tested for cancer. "We will convert an invasive surgical procedure into a minimally invasive needle biopsy," Wang said.

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