Significance: Raman spectroscopy has been developed for surgical guidance applications interrogating live tissue during tumor resection procedures to detect molecular contrast consistent with cancer pathophysiological changes. To date, the vibrational spectroscopy systems developed for medical applications include single-point measurement probes and intraoperative microscopes. There is a need to develop systems with larger fields of view (FOVs) for rapid intraoperative cancer margin detection during surgery. Aim: We design a handheld macroscopic Raman imaging system for in vivo tissue margin characterization and test its performance in a model system. Approach: The system is made of a sterilizable line scanner employing a coherent fiber bundle for relaying excitation light from a 785-nm laser to the tissue. A second coherent fiber bundle is used for hyperspectral detection of the fingerprint Raman signal over an area of 1 cm 2. Machine learning classifiers were trained and validated on porcine adipose and muscle tissue. Results: Porcine adipose versus muscle margin detection was validated ex vivo with an accuracy of 99% over the FOV of 95 mm 2 in ∼3 min using a support vector machine. Conclusions: This system is the first large FOV Raman imaging system designed to be integrated in the workflow of surgical cancer resection. It will be further improved with the aim of discriminating brain cancer in a clinically acceptable timeframe during glioma surgery.

Attainable levels of signal-to-background ratio (SBR) in Raman spectroscopy of biological samples is limited by the presence of endogenous fluorophores. It is customary to remove the ubiquitous fluorescence background using postacquisition data processing. However, new approaches are needed to reduce background contributions and maximize the fraction of the sensor dynamical range occupied by Raman photons. Time-resolved detection using pulsed lasers and time-gated

Raman spectroscopy imaging is a technique that can be adapted for intraoperative tissue characterization to be used for surgical guidance. Here we present a macroscopic line scanning Raman imaging system...

Compared to other transparent infrared fiber materials, ZBLAN fluoride glasses promise to be best suited for laser power delivery in the 3µm wavelength region due to their high transmission and excellent mechanical flexibility. These claims were demonstrated in a series of power handling tests of both straight and coiled fibers using an Er,Cr:YSGG laser emitting a train of pulses of 150 µs duration at a repetition frequency of 20 Hz producing 7.5 W average power. Large core fibers (450/510µm 0,2NA) are characterized by an attenuation of 0.02dB/m at 3µm and stay within 0.5°C from ambient temperature when carrying full laser power. A 2-m fiber length prepared with bare cleaves has been tested for over 23 hours, cumulating 1,140,000 shots of 1530 J/cm 2 fluence while maintaining 90% transmission without any measurable degradation. Coiling the fiber to 11 cm radius did not have an impact on power handling reliability. These results show the potential of these highly transparent fibers in surgical laser delivery applications.

No abstract