504 Improving Precision of Resection Limits in Surgery for High-grade Gliomas: Preliminary Experience with an In Vivo Raman Spectroscopy Probe

Abstract

INTRODUCTION: Supramaximal resection of gliomas to anatomic-functional boundaries is currently widely employed. This leads to removal of potentially tumor-negative thus healthy brain tissue. Therefore, a device that detects glioma tissue infiltrating the white matter in vivo would be valuable. METHODS: Patients and methods. An in vivo Raman spectroscopic system (Sentry 1000, ODS Medical, Montreal, Canada) with an early stage binary classifier trained on 501 samples from 17 patients (tumor n=211 and pure normal n=290 from Montreal Neurological Hospital, Montreal, Canada) has been employed in 15 patients with high-grade gliomas . Of those, 172 samples were collected from 2 areas: n=18 from the central tumor core and n=154 from the adjacent glioma-infiltrated white matter until Raman negative or until an anatomic or functional boundary was reached. All samples were reviewed for the presence of glioma cells by histopathology. RESULTS: Sensitivity of Raman spectroscopy for correct high-grade glioma cells was 79%, specificity for non-infiltrated white matter was 52%. Median resection volume outside MR contrast enhancement was 78 ± 143 cm3. Removal of the infiltration zone guided by Raman spectroscopy revealed a non-concentric growth mainly along white matter fiber bundles. CONCLUSION: According to our data, Raman spectroscopy has the potential to improve the precision of high-grade glioma resection. This may allow a more selective removal of the tumor-infiltrated white matter.