OR Imaging Technique Differentiates Tumors from Normal Tissue

Researchers at the University of Michigan (Ann Arbor; USA) and Harvard University (Boston, MA, USA) used stimulated Raman scattering (SRS) microscopy to differentiate healthy human and mouse brain tissue from tumor-infiltrated brain tissue. The weak Raman signal was magnified by more than 10,000 times, accentuating histoarchitectural and biochemical differences in the tissues, allowing multicolor SRS images to be generated. They also showed a correlation between SRS and hematoxylin and eosin microscopy for the detection of glioma infiltration.

The researchers also found that SRS microscopy was able to successfully differentiate tumor tissue from non-neoplastic tissue in an infiltrative human glioblastoma xenograft mouse model based on their different Raman spectra. Finally, they applied SRS microscopy in vivo in mice during surgery to reveal tumor margins that were undetectable under standard operative conditions. The researchers claim that the rapid intraoperative assessment of brain tissue possible using SRS microscopy could improve the safety and accuracy of surgeries when tumor boundaries are visually indistinct. The study was published in the September 4, 2013, issue of Science Translational Medicine.

“Biopsy has been the gold standard for detecting and removing these types of tumors,” said senior author Harvard professor of chemistry and chemical biology Xiaoliang Sunney Xie, PhD. “But this technique, we believe, is better because it's live. Surgeons can now skip all the steps of taking a biopsy, freezing and staining the tissue—this technique allows them to do it all in vivo.”

Raman spectroscopy is a form of molecular spectroscopy based on Raman scattering. When a beam of light interacts with a material, part of it is transmitted, part it is reflected, and part of it is scattered; over 99% of the scattered radiation has the same frequency as the incident beam, but a small portion of the scattered radiation has frequencies different from that of the incident beam. The scattered radiation contains information about the energies of molecular vibrations and rotations, and these depend on the particular atoms or ions that comprise the molecule, the chemical bonds connect them, the symmetry of their molecule structure, and the physicochemical environment where they reside.

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