OS3.6 Optical Biopsies in Neurosurgery: Raman Spectroscopy for the Real-time Identification of Tumours during Surgery

Abstract

INTRODUCTION: A single centre prospective observational study involving a consecutive series of 30 patients undergoing craniotomy for intrinsic tumours and metastases. Raman spectra were systematically obtained over the normal cortical surface, on route to tumour, superficial and deep tumour zones and the resection cavity. 3D Ultrasound navigation position and a core biopsy for histological analysis was taken at each reading site. Data was classified using machine learning algorithms employing spectral processing and multivariate statistics. The results were compared to 3D ultrasound characteristics and validated using official histopathology. METHOD(S): We report on the first use during Neurosurgery of a stable fibre-optic Raman laser system capable of accurate real-time tissue characterisation of intrinsic brain tumours. The system has been coupled with 3D Neuronavigational ultrasound to give high spatial resolution accounting for brain shift during tumour resection. RESULT(S): Multivariate statistical models including Principle Component Analysis and Linear Discriminant Analysis were built for the classification of healthy and abnormal tissue. Raman spectroscopy was able to give greater than 95% sensitivity and specificity validated by post operative histology for all tumour types studied. CONCLUSION(S): We have successfully demonstrated the use of Raman spectroscopy in Neurosurgery to distinguish different brain tumours. The benefits of an optical biopsy system such as this is immediate non- destructive tissue identification with high spatial resolution which can guide more complete and safer tumour resection by accurately identifying tumour tissue from normal brain tissue. The system integrates easily with operating room workflow and could save time on waiting for frozen section results. Further analysis of the data may reveal novel diagnostic and prognostic biomarkers and new subgroups of patients with differing responses to treatment and survival.