Multi-photon excitation fluorescence microscopy of brain-tumour tissue and analysis of cell density

Background: Recent studies have highlighted the importance of the complete resection of a brain tumour but the task often remains a challenge for the neurosurgeon. New technologies which add objective information beyond visualisation provided by the traditional operating microscope are required. In this study, we have analysed the cellular density of the tumour/brain interface using three dimensional multi-photon microscopy intensity-images of experimental gliomas and human brain-tumour biopsy samples. Methods: The density of cellular nuclei was determined in specimens of experimental gliomas in a mouse model and human brain tumour biopsies by analysis of optical tissue sections. Three dimensional multi-photon microscopy image stacks were compared to serial H&E stained sections of conventional histolopathology. Findings: Both techniques consistently showed a good correlation of cell density values in solid tumour tissue of experimental gliomas versus adjacent brain. The multi-photon microscopy analysis of human biopsy specimens showed that optical analysis of native tissue provided information on the cellular density. Conclusions: Multi-photon microscopy is an efficient and rapid tool for the study of brain and brain tumour tissue. Multi-photon microscopy allows the detection of individual tumour cells and tumour cell clusters in native tissue biopsies and may therefore provide a tool in the identification of highly cellular lesions during the resection of brain tumours.