Combined autofluorescence and diffuse reflectance for brain tumour surgical guidance: initial ex vivo study results

Abstract

This ex vivo study was conducted to assess the potential of using a fibre optic probe system based on autofluorescence and diffuse reflectance for tissue differentiation in the brain. A total of 180 optical measurements were acquired from 28 brain specimens (five patients) with eight excitation and emission wavelengths spanning from 300 to 700 nm. Partial least square-linear discriminant analysis (PLS-LDA) was used for tissue discrimination. Leave-one-out cross validation (LOOCV) was then used to evaluate the performance of the classification model. Grey matter was differentiated from tumour tissue with sensitivity of 89.3% and specificity of 92.5%. The variable importance in projection (VIP) derived from the PLS regression was applied to wavelengths selection, and identified the biochemical sources of the detected signals. The initial results of the study were promising and point the way towards a cost-effective, miniaturized hand-held probe for real time and label-free surgical guidance.

Layer thickness prediction and tissue classification in two-layered tissue structures using diffuse reflectance spectroscopy

“…The detected diffuse reflectance spectrum of this light represents an “optical fingerprint” of the measured tissue, which can be analyzed. DRS has been successfully evaluated for detection of cancer in breast 20 , 21 , 29 , colorectal 30 – 34 , head and neck 22 , 35 , 36 , liver 23 , 24 , lung 25 , 26 , and brain 27 , 28 tissue, in both ex vivo and in vivo studies. These studies showed that tumor tissue could be discriminated from healthy tissue with classification accuracies of 0.77–1.00, suggesting this technique has a great potential for real-time tissue assessment during surgery.…”

Silicon Photomultiplier—A High Dynamic Range, High Sensitivity Sensor for Bio-Photonics Applications

“…Bio-photonics uses light–tissue interactions such as reflectance, scattering, absorption, time-of-flight (ToF) and fluorescence to evaluate the properties and composition of tissues [ 1 ]. These diagnostic techniques can be performed on in vivo and ex vivo tissue through minimally invasive procedures, offering attractive alternatives to traditionally used medical diagnostic tools and also enabling research for the next generation of medical devices [ 2 , 3 ]. These devices are traditionally optical fibre based and integrated into a catheter or guidewire for intra operative use for surgical guidance and diagnostics [ 3 ].…”

“…This integrated ASIC and SiPM will have particular application for brain tumour margin resection using auto-fluorescence (AF) [ 3 , 4 , 5 ]. Additionally, use of multispectral and hyperspectral optical source techniques for deep tissue measurements and AF measurements for biomarker detection further challenges the sensitivity and dynamic range requirements of detectors and their supporting electronics [ 2 , 4 , 6 ].…”

“…However, some published works contain detailed discussion of the photodetectors employed. Some of the research listed here used photodiodes (PDs) [ 8 , 9 ], avalanche photodiodes (APDs) [ 2 , 4 , 10 , 11 , 12 , 13 , 14 ], single photon avalanche photodiodes (SPADs) [ 15 ], and silicon photomultipliers [ 16 , 17 , 18 , 19 , 20 ]. These works primarily focus on the specific bio-photonics applications rather than discussing the specifications of the photo detection devices.…”

Multi-Spectral Clinical Prototype for Fluorophore Detection

“…Hence, this study presents a novel, fibre-based optical instrument with extended dynamic range, capable of continuously compensating for ambient illumination while performing contact point measurements. The instrument presented builds on our previous study [34]. The major novelty aspect of the system is its capability to measure concentrations of two independent fluorophores in diffuse media with large variation of absorption and scattering.…”