Spatially-Resolved Multiply-Excited Autofluorescence and Diffuse Reflectance Spectroscopy: SpectroLive Medical Device for Skin In Vivo Optical Biopsy

Abstract

This contribution presents the development of an optical spectroscopy device, called SpectroLive, that allows spatially-resolved multiply-excited autofluorescence and diffuse reflectance measurements. Besides describing the device, this study aims at presenting the metrological and safety regulation validations performed towards its aimed application to skin carcinoma in vivo diagnosis. This device is made of six light sources and four spectrometers for detection of the back-scattered intensity spectra collected through an optical probe (made of several optical fibers) featuring four source-to-detector separations (from 400 to 1000 µm). In order to be allowed by the French authorities to be evaluated in clinics, the SpectroLive device was successfully checked for electromagnetic compatibility and electrical and photobiological safety. In order to process spectra, spectral correction and metrological calibration were implemented in the post-processing software. Finally, we characterized the device’s sensitivity to autofluorescence detection: excitation light irradiance at the optical probe tip in contact with skin surface ranges from 2 to 11 W/m², depending on the light source. Such irradiances combined to sensitive detectors allow the device to acquire a full spectroscopic sequence within 6 s which is a short enough duration to be compatible with optical-guided surgery. All these results about sensitivity and safety make the SpectroLive device mature enough to be evaluated through a clinical trial that aims at evaluating its diagnostic accuracy for skin carcinoma diagnosis.

Proposal for a Skin Layer-Wise Decomposition Model of Spatially-Resolved Diffuse Reflectance Spectra Based on Maximum Depth Photon Distributions: A Numerical Study

“…The geometrical and optical features of source and detection fibers implemented in our SR-DRS simulations were based on the technical characteristics of an existing device developed by our team [37], whose purpose is to assist a surgeon in establishing surgical margins during skin carcinoma resection [38]. Work with a similar goal has already been presented in the literature using DR [39] (elastic scattering) or Raman [40] (inelastic scattering) spectra.…”

“…The values of the volume fraction and mass concentration of each chromophore applied in every layer of our numerical model are summarized in Table 5. They were chosen following (i) a literature review [47,49,52,53] and (ii) comparisons between simulated spectra and experimental data acquired in clinics [38] (see Figure 3) using our SR-DRS device [37].…”

Impact of optical clearing on ex vivo human skin optical properties characterized by spatially resolved multimodal spectroscopy

“…The SpectroLive device was used to acquire SR DR and multiply excited AF intensity spectra (see Refs [50,51]. for detailed technical and metrological features).…”

Hierarchic Clustering-Based Face Enhancement for Images Captured in Dark Fields

“…Thus the value k can be estimated by the ratio between the middle-level and the next to last-level gray values of the clustered image (Equations ( 3) and ( 4)). When dealing with the over bright region, the diffuse reflectance [26] can be defined and computed by ( 5) and ( 6); and its estimation can be calculated by (7). Clearly, the bigger the diffuse reflectance A is, the better the face recognition effect will be:…”