Wide-field and non-invasive imaging of brain tumours with scattered light techniques.

The ability to identify tumour tissue in a label-free, contactless, and real-time manner is much needed in tumour resection surgery. Current techniques cause interruptions to surgical flow and have high false positive rates, which can cause collateral damage to healthy brain tissue. We propose laser light scattering techniques, such as diffuse correlation spectroscopy and laser speckle contrast imaging, to image mechanical stiffness differences in the brain's surface associated with tumour tissue. We validate the optimal processing technique quantitatively with a controlled experiment in which paraformaldehyde was used to induce a change in tissue stiffness in ex vivo mouse brains. We then demonstrate that the technique applies to tumour localisation using ex vivo mouse models with real tumours. Qualitative comparisons with magnetic resonance imaging indicate accurate tumour localisation using only surface stiffness changes to underlying tumours. We also demonstrate sub-millimetre precision when imaging brain slices.