The NIR-II dye can resolve blood vessels in the forelimb as well as the brain with unprecedented clarity. The dye also allows clear resolution of tumors in the center of the mouse’s brain.
At Stanford and elsewhere, researchers have worked to create dyes that, when stimulated, emit light of long wavelengths close to infrared light. Such a light, which is not visible to the human eye, could then be viewed by a special camera and be projected to a monitor to produce deeper, sharper images from inside the body. It can help to pinpoint tumor locations near the skin’s surface in a variety of cancers, such as head and neck, melanoma and breast cancer.
Most dyes have safety concerns: Some made from carbon nanotubes or quantum dots can linger in the body for days and months, caught in the liver and spleen, before being excreted slowly. This drawback thus far has prevented their use in humans. Stanford scientists solved that problem with molecular fluorescent dyes that produce light in a portion of the near infrared range known as the second near-infrared window, or NIR-II. Dyes emitting light in that range have long wavelengths that can escape from tissues with little scattering, thus producing better images.
Led by chemistry Professor Hongjie Dai, the team has created a dye that can be excreted through urine within 24 hours, a development that may at some point make this valuable imaging procedure available for human health care. What’s more, the new dye produces images that are sharper and more detailed than before, increasing their potential value to medicine and surgery, Antaris said.
NIR-II fluorescence imaging has potential as a surgical guide because it can capture video in real time, a striking contrast to tomographic imaging techniques, which can take minutes to hours to complete one scan.
“This could enable clinical use of fluorescence imaging to reach unprecedented depth for diagnostics or imaging guided surgery,” Dai said.
http://news.stanford.edu/news/2015/december/dye-dai-imaging-121915.html
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