NEW YORK (Reuters Health) - US researchers have developed near-infrared “quantum dots” that could improve the mapping of sentinel lymph nodes (SLN) for a variety of malignancies, according to a report in the December 7th online issue of Nature Biotechnology.
The technique involves the injection of the quantum dots, which fluoresce in the near infrared, at the site of the primary tumor. Looking through a special imaging device, the surgeon can then follow the course of the dots as they travel from the tumor, through the lymph vessels, and into the sentinel node.
“Currently, SLN mapping is done with a combination of radioactivity and a blue dye,” senior author Dr. John V. Frangioni, from Beth Israel Deaconess Medical Center in Boston, told Reuters Health. Unfortunately, this approach “really doesn’t guide the surgeon in where to make the initial incision, and there is a huge learning curve,” he added.
“What we’ve developed is a system that allows the surgeon to do the entire procedure under optical guidance,” Dr. Frangioni noted. “With this system, there is no question where the lymph is flowing or where the sentinel node is.”
Because the near-infrared fluorescence is transmitted through skin and tissue, the lymphatic tract is clearly defined and the surgeon knows beforehand where to make the initial incision, he added.
In the current study, the researchers used the dots to map various sentinel nodes in animals. Nodes up to 1 cm deep were successfully imaged.
“This is a proof of principle study,” Dr. Frangioni emphasized. “The quantum dots are actually made of chemicals, such as lead and cadmium, that are quite toxic.”
“We are currently working on molecules that can be safely injected into humans,” Dr. Frangioni noted. “Also, we plan on improving the depth of imaging by using more complicated optics.”
Source: Nat Biotechnol 2003. [ Google search on this article ]
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