Feasibility of integrated high‐wavenumber Raman imaging and fingerprint Raman spectroscopy for fast margin assessment in breast cancer surgery

Abstract

Intraoperative assessment of surgical margins remains one of the main challenges in cancer surgery. Raman spectroscopy can detect cancer cells with high accuracy, but it is time-consuming. In this paper, we investigated a selectivesampling Raman spectroscopy approach, based on high wavenumber (HW) Raman imaging (spectral range 2,500-3,500 cm −1) and fingerprint Raman spectroscopy (spectral range 600-1,800 cm −1), to reduce the overall tissue analysis time while maintaining high diagnostic accuracy. HW Raman mapping was used as a first step to identify the adipose tissue regions based on the C-H stretching bands at 2,700-2,950 cm −1. As residual tumors are typically found in nonadipose tissue, an algorithm was developed to allocate sampling points for fingerprint Raman spectroscopy at locations corresponding to low intensity in the HW-Raman maps. Preliminary results show that HW-Raman imaging based on a 671 nm laser is effective and fast for mapping of adipose tissue in breast resections, with typical imaging times of 2 min for tissue areas as large as 2 × 2 cm 2 areas. Albeit the remaining high fluorescence background in the fingerprint region prevents the use of single 671-nm laser, the HW Raman imaging can be still exploited in combination with 785-nm excitation Raman spectroscopy for identifying residual tumor. Although this study demonstrates the feasibility of this approach, further improvements, such as using single element detectors for HW Raman imaging, are required to increase the analysis speed further towards intraoperative use in the routine clinical setting.

Mesoscopic fluorescence lifetime imaging: Fundamental principles, clinical applications and future directions

“…Diffuse reflectance spectroscopy and diffuse optical imaging exploit the heterogeneous absorption and scattering properties of light in tissue for breast cancer management [21–23] and has also been applied to assess brain tissue [24,25]. Raman spectroscopic imaging has remarkable molecular specificity and it has been used in preliminary studies for guiding surgeries and identifying tumors and cancerous tissue in head and neck [26–32], brain [33–35], skin [36,37], breast [38–41] and the gastrointestinal track [42–45], among others [46].…”

Selective-sampling Raman imaging techniques for ex vivo assessment of surgical margins in cancer surgery

“…For this purpose, alternative imaging techniques can be used, as long as they are fast and have high sensitivity to the required features of interest. Such optical techniques include confocal fluorescence microscopy 46, 47, , high-wavenumber Raman spectroscopy 55 , coherent anti-Stokes Raman-scattering, second harmonic generation 56,57 and quantitative phase microscopy 58 . These techniques can be used to identify regions of interest in the samples and screen out regions that can be confidently identified as normal tissue.…”

“…While the initial studies in selective-sampling Raman spectroscopy employed a second optical modality for determining the spatial properties of the sample, Liao et al investigated the combination of high wavenumber (HW) Raman imaging (spectral range 2,500-3,500 cm -1 ) and fingerprint Raman spectroscopy (spectral range 600-1,800 cm -1 ). HW-Raman imaging was used to identify adipose tissue by targeting the C-H stretching bands of lipids at 2,700-2,950 cm -1 , an then the areas identified as non-adipose tissue were further investigated by fingerprint Raman spectroscopy in order to provide an accurate classification 55 .…”

Handheld macroscopic Raman spectroscopy imaging instrument for machine-learning-based molecular tissue margins characterization

“…Many Raman microscopes have been developed with the intention of guiding surgery by assisting pathologists in the visualization of tissue margins in excised tissue (e.g., breast, 30 skin, 31 and oral 32 cancer). These systems can cover areas up to several , but they are unsuitable for performing molecular imaging in vivo .…”