SURG-01. AN INTRAOPERATIVE RAMAN SPECTROSCOPIC PROBE FOR GLIOMA SURGERY: INDICATIONS, SAFETY, AND FUTURE DIRECTIONS

Abstract

INTRODUCTION: Raman spectroscopy is a tool that utilizes a noncontact label-free modality of optical imaging that measures inelastic scattered photon shifts to give a unique biochemical signature. There is established work showing that these unique fingerprints can differentiate a glioma from necrosis and normal brain. The ability to instantly characterize these organic tissues intraoperatively, then, can help guide a surgeon's resection. The goal of the present study is to review the Raman work that has been performed to date, its demonstrated safety in a rat model and the indications for use of this operative tool. METHOD(S): We review the fundamental principles of Raman spectroscopy, some contemporary data, and show its effectiveness as an intraoperative probe. Because the probe uses a 100mW 785nM laser wavelength, we also determined the threshold at which it causes damage to cortical grey matter in a rat model. RESULT(S): Raman spectroscopy has a high sensitivity and specificity (>97%) when discriminating between grey matter, necrosis and GBM. A discriminant function analysis, supervised classification algorithm, is used for spectral identification to allow relevant spectral interpretation and allows for tailoring to which Raman peaks are significant for diagnosis. In regards to safety, animal experiments showed no damage seen at 10 seconds/250mW and estimated damage to occur at 60 seconds/250mW. We also present an intraoperative workflow of how this tool could be used in the operating room. CONCLUSION(S): A Raman spectrographic probe is a safe and powerful tool that can provide live intraoperative diagnosis and identify tissue margins. Further work is being done to identify clinical outcomes, the unique fingerprints of other pathological tissues and further differentiate gliomas based on molecular markers like IDH-1.