Synchrotron enables faster, better tissue imaging

Compiled by Photonics Spectra staff

A synchrotron-based imaging technique delivers intensity a million times brighter than sunlight – and offers high-resolution pictures of the molecular composition of tissues with high speed and quality.

A team of researchers from the University of Wisconsin-Milwaukee (UWM), the University of Illinois at Urbana-Champaign and the University of Illinois at Chicago demonstrated the capabilities of the new method, led by Carol Hirschmugl, a physicist at UWM. Along with UWM scientist Michael Nasse, Hirschmugl built a facility called Infrared Environmental Imaging (IRENI) to perform the technique at the Synchrotron Radiation Center at the Madison campus of the University of Wisconsin. The technique provided by the facility employs multiple beams – instead of just one – of synchrotron light to illuminate a state-of-the art camera.

IRENI cuts the amount of time required to image a sample from hours to minutes while quadrupling the range of the sample size and producing high-resolution images that do not have to be tagged or stained as they would with an optical microscope. Revealing the molecular composition, structure and chemistry of a tissue sample, IRENI enables users to see the distribution of function groups, such as proteins, carbohydrates and lipids.

IRENI-generated images (right) are 100 times less pixelated than those created by conventional infrared imaging (left). The difference is the result of multiple synchrotron beams, which provided enough light to obtain a detailed image of the sample. With the technique, the quality of the chemical images is now similar to that of optical microscopy. Courtesy of Carol Hirschmugl and Michael Nasse, University of Wisconsin-Milwaukee.

The unique features of the synchrotron make it a versatile light source for spectroscopy. Streams of speeding electrons emit continuous light across the entire electromagnetic spectrum so that researchers can access whatever wavelength is best absorbed for a particular purpose. The team used the mid-IR range to form graphic fingerprints of biochemically important molecules.

Using 12 beams of synchrotron light in this range allows researchers to collect thousands of chemical fingerprints simultaneously, producing an image that is 100 times less pixelated than in conventional IR imaging. The team tested the technique on breast and prostate tissue samples to determine its potential for diagnosing cancer and other diseases. With unprecedented detail, it detected features that distinguish epithelial cells, in which cancer begins, from stromal cells, which are found in deeper tissues.

The technique could open the door to a broad spectrum of applications in medicine, pharmaceutical drug analysis, art conservation, forensics, biofuel production and advanced materials such as graphene, Hirschmugl said.

The team’s findings, which were published online March 20, 2011, in Nature Methods (doi: 10.1038/nmeth.1585), could lead to synchrotron-based imaging that can monitor cellular processes from simple metabolism to stem cell specialization.