6. Autofluorescence as a parameter in tumor diagnosis: Application in neurosurgery

The autofluorescence properties of a biological tissue depend on both the amount and the distribution of the endogenous fluorophores, which, in turn, can be related to the histological organization and metabolic functions of the tissue. Tissue alterations induced by neoplasia can result in changes in the fluorescence signal amplitude and spectral shape, that can be exploited for diagnostic purposes. In this work, a preliminary investigation is reported concerning the autofluorescence as a possible tool for intraoperative delineation of brain tumor resection margin. To this aim, autofluorescence properties of normal tissue and glioblastoma were investigated, both on tissue sections from ex vivo samples, by means of microspectro-fluorometric techniques, and directly on living tissues during surgical operation, via fiber optic probe. Differences in terms of emission amplitude and spectral shape between glioblastoma and normal surrounding tissue were found in ex vivo samples. In patients, highly significant differences were found in terms of emission amplitudes, the fluorescence intensity measured in tumor being 2030% and 40-70% of that measured in white matter and cortex, respectively. The difference found in vivo are greater than those expected according to the results of the microspectrofluorometric analysis on tissue sections, and could be attributable to changes in optical properties of the tissues.