bloody tangle. a new laser scanning technology reveals the vasculature of the brain of a rat.
BALTIMORE, Maryland- - Biology does not get much more basic - or much more work - histology, examination of the finer details of tissue samples. Now, researchers say they have developed a laser-based approach that can produce 3D high resolution images in a fraction of the time required for traditional techniques.
histology usually involves freezing a tissue sample, cut into thin slices and staining with dyes that label different components. Researchers take images and digitally colored sections recombine to reconstruct a three-dimensional view. But such reconstructions are often hampered because the blades can move components around.
So, a group led by Jeff Squier, a physicist laser at Colorado School of Mines Golden, turned to a laser capable of shooting light pulses lasting only 20 quadrillionths of a second. Such short pulse lasers are useful for imaging of fluorescent molecules within the upper fabric layer and for the removal of thin layers of tissue. Squier's team decided to put the two jobs at once.
In one experiment, the team used the laser to scan the brain tissue of rats engineered to express a fluorescent protein in cells that line the blood vessels in the cerebral cortex. They shot a series of low-intensity infrared pulses, which triggered the protein designed to emit photons of light yellow. The light is captured by a camera and stored on a computer. Then the researchers bent the laser enough to take off the first 10 microns of tissue. They repeated imaging and ablation steps several times and then used a computer to integrate the image file in a 3D view of the vasculature of the brain of a rat. Squier presented the findings here on June 2 at the meeting of the Conference on Lasers and Electro-Optics.
"It is a very promising technique," said Virginijus Barzda a biophysicst at the University of Toronto in Canada. Barzda noted that this technique enables researchers to produce images with a resolution of about 1 micron much better than conventional techniques such as magnetic resonance imaging that peers through tissue. But because the laser destroyed the sample Barzda and others say it is unlikely to be useful for traditional clinical pathology tests on human tissue, because doctors generally prefer to save the samples so they can be reviewed later.
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