title: Miniature standoff Raman probe for neurosurgical applications.
abstract: Removal of intrinsic brain tumors is a delicate process, where a high degree of specificity is required to remove all of the tumor tissue without damaging healthy brain. The accuracy of this process can be greatly enhanced by intraoperative guidance. Optical biopsies using Raman spectroscopy are a minimally invasive and lower-cost alternative to current guidance methods. A miniature Raman probe for performing optical biopsies of human brain tissue is presented. The probe allows sampling inside a conventional stereotactic brain biopsy system: a needle of length 200 mm and inner diameter of 1.8 mm. By employing a miniature stand-off Raman design, the probe removes the need for any additional components to be inserted into the brain. Additionally, the probe achieves a very low internal silica background while maintaining good collection of Raman signal. To illustrate this, the probe is compared with a Raman probe that uses a pair of optical fibers for collection. The miniature stand-off Raman probe is shown to collect a comparable number of Raman scattered photons, but the Raman signal to background ratio is improved by a factor of five at Raman shifts below ∼500  cm(−1). The probe’s suitability for use on tissue is demonstrated by discriminating between different types of healthy porcine brain tissue.
authors.affiliation: University of Bristol, Interface Analysis Centre, H.H. Wills Physics Laboratory, Tyndall Avenue, Bristol BS8 1TL, United Kingdom.
authors.forename: Oliver A C
authors.initials: OA
authors.lastname: Stevens
authors.affiliation: University of Bristol, Interface Analysis Centre, H.H. Wills Physics Laboratory, Tyndall Avenue, Bristol BS8 1TL, United KingdombBiophotonics Research Unit, Gloucestershire Hospitals NHS Foundation Trust, Gloucester GL1 3NN, United Kingdom.
authors.forename: Joanne
authors.initials: J
authors.lastname: Hutchings
authors.affiliation: Cardiff University, Neuroscience and Mental Health Research Institute, Schools of Medicine and Biosciences, Cardiff CF14 4XN, United Kingdom.
authors.forename: William
authors.initials: W
authors.lastname: Gray
authors.affiliation: Pfizer, 230 East Grand Avenue, South San Francisco, California 94080, United States.
authors.forename: Rosa Louise
authors.initials: RL
authors.lastname: Vincent
authors.affiliation: University of Bristol, Interface Analysis Centre, H.H. Wills Physics Laboratory, Tyndall Avenue, Bristol BS8 1TL, United Kingdom.
authors.forename: John C
authors.initials: JC
authors.lastname: Day
mesh_terms: D000818:Animals; D001706:Biopsy; D001932:Brain Neoplasms / Q000000981:diagnostic imaging*; D004867:Equipment Design; D006801:Humans; D009493:Neurosurgery / Q000295:instrumentation*; D055100:Optical Fibers; D013059:Spectrum Analysis, Raman; D013552:Swine