Shadowing a DoctorMarch 20, 2014
In the ongoing fight against brain cancer, surgeons now have an innovative new weapon – an imaging technique that has the potential to dramatically increase accuracy in brain surgery leaving almost no room for error. Called SRS microscopy or Stimulated Raman Scattering, this technology creates a marked distinction between diseased and healthy cells and shows surgeons exactly where the tumour ends and the brain begins. This allows surgeons to distinguish clearly between tumours and brain tissue at a microscopic level, which can greatly boost the accuracy of brain surgery.
This innovative technique was developed by a team of scientists from Harvard University and the University of Michigan who were looking for a better way to image brain tumours so as to reduce the risk potential of brain cancer surgery.
Brain tissue and tumours have different chemical compositions. Using that as the basis, the researchers aimed at devising a method to create images that show the boundary area with higher precision so that the margin where tumour cells infiltrate into normal cells is more clearly visible. This would act as a more accurate guide for surgeons in the operating room. With SRS microscopy it will be possible for surgeons to remove every last bit of the tumour tissue without worrying about accidently removing any healthy tissue.
Traditionally, biopsy has been the gold standard for detecting and removing these types of tumours but it had its limitations. When operating to remove brain tumours, it isn’t always possible for the surgeon to tell if all of the offending tumours have been removed or if any still remain. Any attempt to remove more of the harmful tissue increases the risk of cutting into healthy tissue.
A surgeon who is very experienced may be able to differentiate between healthy brain tissue and a dangerous tumour based on subtle differences in colour, but to many surgeons the colour differences are almost undetectable.
In this respect SRS microscopy is shows tremendous promise as it allows surgeons to see something that would have been invisible through conventional surgical microscopy.
How Stimulated Raman Scattering Works
In the Stimulated Raman Scattering technique, the brain is hit by a non-invasive laser which is capable of sensing the slightest resonance in chemical bonds. The spectrum of light that is emitted is analysed. This high sensitivity of the laser light helps it distinguish lighter healthy tissue from denser tumour tissue by showing the variations in the amount of proteins and lipids in cells. Proteins appeared blue while lipids were green. Tumours, which are typically rich in protein, showed up bright blue.
The researchers suggested that SRS microscopy could potentially be as accurate as Hematoxylin and eosin (H&E) staining, which is the current approach used in brain tumour diagnosis. The difference is that SRS microscopy can be done in real time, without having to dye, remove or process the tissue, which could be complicated, laborious and time consuming.