P07.12.B Brain Biopsy with Optical Guidance

Abstract

Abstract Background Accurate stereotactic biopsies of brain tumors are imperative for diagnosis and decisions on therapy. Repetitive needle insertions owing to inconclusive tissue samples enhance increased risks of brain lesioning, hemorrhage and prolonged procedure. Previously we reported on frame-based stereotactic biopsies with a combined 5-ALA fluorescence and laser Doppler flowmetry detection system[1]. The system has now been adapted to frameless navigation with a modified biopsy needle and a new registration system[2]. Material and Methods Planning was effected with the Medtronic Stealth System. The optical probe was inserted inside the outer cannula of the biopsy needle, which had an opening at the tip, enabling optical measurements ahead of the needle in real-time while manually forwarding it along the trajectory to the target. Fluorescence spectra, microvascular blood flow, and tissue grayness were recorded during insertion. The biopsies were taken where the fluorescence indicated tumor tissue; the optical probe was replaced by the inner cannula. The diagnoses were compared with the fluorescence signals. Results In the 9 examined patients the fluorescence measurements and pathological diagnosis of high-grade gliomas or lymphomas matched. Only one needle insertion was necessary. The optical measurements along the trajectory took 5-10 min to the target, the pathological diagnosis was reported after 30-70 min. The probe provided direct feedback of increased blood flow along the trajectory and of malignant tissue in the vicinity of the target. Conclusion The optical probe can detect tumor before any tissue is retrieved. If fluorescence is registered, pathological tissue is safely identified. The method can increase the precision and safety of the biopsy and shorten the procedure. The new multimodal probe and the improved registration unit will be tested with other stereotactic and navigation systems and at other neurosurgical centers. Also, the parallel project on fluorescence guided resection of high-grade gliomas is continued[3].