5-AMINOLEVULINIC ACID INDUCED PROTOPORPHYRIN IX FLUORESCENCE FOR DETECTION OF BRAIN TUMOR CELLS IN VIVO
The use of optical methods for brain tumor diagnostics was evaluated according to the differences of fluorescence spectra. The in vivo biological tissue autofluorescence and the induction of endogenous porphyrins after i.v. injection of 5-aminolevulinic acid (ALA) were studied in Wistar rats bearing 101.8 brain tumors. Light induced fluorescence techniques were applied to in vivo detection of spectral signatures of endogenous porphyrins in malignant tissues and host normal brain. Animal models of cerebral glioma were prepared by implanting 101.8-glioma cells suspension into Wistar rats left parietal brain region. After 14 days craniotomy was performed on tumor-bearing animals. Time-dependent accumulation of endogenous porphyrins in brain tissues following i.v. administration of 300 mg/kg ALA has been examined using OMA (optical multichannel analyzer) and fiber optic probe. Normal brain tissue showed low endogenous (exogenous) porphyrin fluorescence, whereas tumor tissue was distinguished by bright fluorescence at wave lengthes 635 and 705 nm. The intracellular uptake of PpIX after ALA i.v. injection occurs selectively in tumor tissue resulting in maximum tumor/normal brain fluorescence contrast ratio appearing 6 h after the injection. ALA induced PpIX fluorescence might be used for intraoperative diagnosis of gliomas.
No Comments » Add comments