Coherent anti-Stokes Raman scattering and two photon excited fluorescence for neurosurgery

• CARS and TPEF provide cytological, histological and molecular information.
• The methods function also in vivo and no staining of tissue is necessary.
• The images enable to clearly identify different tissue types.
• CARS and TPEF will contribute to avoid the collection of non-representative material.
• CARS and TPEF will decrease the risk to injure eloquent brain tissue and minimize the risk to injure blood vessels.

ObjectiveThere is no established method for in vivo imaging during biopsy and surgery of the brain, which is capable to generate competitive images in terms of resolution and contrast comparable with histopathological staining.MethodsCoherent anti-Stokes Raman scattering (CARS) and two photon excited fluorescence (TPEF) microscopy are non-invasive all optical imaging techniques that are capable of high resolution, label-free, real-time, nondestructive examination of living cells and tissues. They provide image contrast based on the molecular composition of the specimen which allows the study of large tissue areas of frozen tissue sections ex vivo.ResultsHere, preliminary data on 55 lesions of the central nervous system are presented. The generated images very nicely demonstrate cytological and architectural features required for pathological tumor typing and grading. Furthermore, information on the molecular content of a probe is provided. The tool will be implemented into a biopsy needle or endoscope in the near future for in vivo studies.ConclusionWith this promising multimodal imaging approach the neurosurgeon might directly see blood vessels to minimize the risk for biopsy associated hemorrhages. The attending neuropathologist might directly identify the tumor and guide the selection of representative specimens for further studies. Thus, collection of non-representative material could be avoided and the risk to injure eloquent brain tissue minimized.