Characterization of a Raman spectroscopy probe system for intraoperative brain tissue classification.

Joannie Desroches,Eric Marple,Kelvin Mok,Karl St-Arnaud,Jeanne Mercier,Kirk Urmey,Cédric Lemieux-Leduc,Kevin Petrecca,Frédéric Leblond,Michael Jermyn,Marie-Christine Guiot

doi:10.1364/boe.6.002380

Abstract

A detailed characterization study is presented of a Raman spectroscopy system designed to maximize the volume of resected cancer tissue in glioma surgery based on in vivo molecular tissue characterization. It consists of a hand-held probe system measuring spectrally resolved inelastically scattered light interacting with tissue, designed and optimized for in vivo measurements. Factors such as linearity of the signal with integration time and laser power, and their impact on signal to noise ratio, are studied leading to optimal data acquisition parameters. The impact of ambient light sources in the operating room is assessed and recommendations made for optimal operating conditions. In vivo Raman spectra of normal brain, cancer and necrotic tissue were measured in 10 patients, demonstrating that real-time inelastic scattering measurements can distinguish necrosis from vital tissue (including tumor and normal brain tissue) with an accuracy of 87%, a sensitivity of 84% and a specificity of 89%.

Highlights

Gliomas are aggressive brain cancers characterized by diffuse infiltrating borders with cancer cells invading the surrounding normal brain tissue
To address this clinical problem, we have developed a hand-held contact Raman spectroscopy (RS) probe technique for real-time tissue classification based on intrinsic inelastic scattering contrast
It consists of a hand-held probe (EmVision LLC, FL, USA), a spectrally stabilized laser emitting in the near-infrared (NIR) at 785 nm (Innovative Photonic Solutions, NJ, USA), a navigation attachment (Suretrack, Medtronic, CO, USA) installed on the probe, a high speed and high-resolution charge-coupled device (CCD) spectrometer (ANDOR Technology, Belfast, UK), and a computer controlling the optical hardware for intraoperative data acquisition

Summary

Introduction

Gliomas are aggressive brain cancers characterized by diffuse infiltrating borders with cancer cells invading the surrounding normal brain tissue. Several studies demonstrated that surgical metrics, such as volume of resected tumor or completeness of resection based on observed residual contrast on post-operative MR scans, correlate with progression-free and overall survival [2,3,4,5] This is because residual invasive cancer cells invariably remain following surgery, often leading to disease recurrence. Glioma surgery differs from several other surgical oncology procedures (e.g., skin, breast, mouth & throat cancer) in that no safety margins can be removed since unnecessary removal of normal brain tissue can often lead to neurological deficits with a direct negative impact on patient health such as impaired cognition, memory, strength and vision [5, 6] To address this clinical problem, we have developed a hand-held contact Raman spectroscopy (RS) probe technique for real-time tissue classification based on intrinsic inelastic scattering contrast. Ensuring that biopsy samples are not collected in a necrotic area is essential

System characterization procedure and results

System description

Signal to noise ratio

Findings

Discussion