BACKGROUND:Glioblastoma (GBM) remains the most aggressive primary brain tumor, and intraoperative frozen section analysis is the current standard for rapid histopathological assessment. However, this approach is time-consuming and resource-intensive. Stimulated Raman scattering (SRS) imaging has emerged as a label-free technique enabling near real-time microscopic evaluation of fresh tissue. This study compares the visualization of selected histopathological features in a newly developed intraoperative SRS system with conventional hematoxylin-eosin (HE) staining in confirmed GBM. METHODS:Tumor samples from 30 patients with neuropathologically confirmed GBM were analyzed. For each case, both HE-stained frozen sections and SRS-generated virtual HE-like images were prepared from separate portions of the specimen. Twelve neuropathologists with varying levels of experience assessed 60 images according to seven predefined GBM criteria, resulting in 720 image evaluations. Feature detection was analyzed using cluster-adjusted generalized estimating equation models, and interobserver agreement was assessed using Fleiss' κ. RESULTS:Descriptively, hypercellularity and hypervascularization were identified at similar frequencies in both modalities, whereas pleomorphism, endothelial proliferation, mitotic activity, and necrosis were more often recognized in HE images. In cluster-adjusted analyses, SRS showed significantly lower detection rates for hypercellularity, pleomorphism, endothelial proliferation, and mitotic activity, while no significant difference was observed for hypervascularization, necrosis, or pseudopalisading after false discovery rate correction. Interobserver agreement was feature-dependent and generally higher for HE than SRS, particularly for hypercellularity. CONCLUSIONS:In this feature-level analysis of neuropathologically confirmed GBM, SRS imaging provided rapid, label-free morphological information and showed comparable visualization of selected histopathological features, particularly hypervascularization. While conventional HE-stained frozen sections remained superior for certain WHO-defining features, SRS represents a promising intraoperative adjunct that may complement established neuropathological workflows. Further studies including non-tumor tissue and a broader range of glioma grades are needed to determine the full diagnostic accuracy and clinical applicability of this technique.

We present a fully integrated, clinical-compatible SRS imaging device giving access to the complete Raman spectrum for histological tissue examination during tumor surgeries.

Hyperspectral Stimulated Raman Imaging (SRS) has shown great promise as a label-free chemical imaging technique in biomedical and medical research. We present recent developments in SRS integrating a compact and portable all-fiber laser with balanced detection into an imaging system, aiming to enhance ease-of-use, specificity, and reliability in acquiring high-speed, multicolor chemical images. The system's adaptability is highlighted by its seamless integration with a Nikon Eclipse Ti widefield microscope, providing a compact and robust extension for varied imaging setups. The system incorporates a balanced detector to enable shot-noise-limited measurements, accommodating over 100mW of Stokes power on the detector.

We present a fully integrated, clinical-compatible SRS imaging device giving access to the complete Raman spectrum during tumor surgeries. Leveraging the advantages of a compact and robust fiber laser, we have integrated the entire microscopy system into a clinical cart, facilitating deployment in diverse clinical environments. The laser provides rapid tunability within milliseconds across a broad spectral range of 700 to 3300 cm^-1, covering biomedically relevant resonances in the fingerprint region. For detailed examination of larger tissue samples, we have designed a high-speed, low-resolution imaging mode to quickly identify cancerous hot-spots, followed by a high-resolution imaging mode.

We present a fully integrated, clinical-compatible SRS imaging device giving access to the complete Raman spectrum for histological tissue examination during tumor surgeries.

We present a turn-key portable picosecond fiber laser for efficient quantum dot excitation to generate single photons. The laser combines a mode-hop-free tunability in the regions 770-980 nm and 1150-1500 nm with a high pulse-to-pulse coherence of 98%. A high single photon purity and indistinguishability were demonstrated. An excellent long-term power stability with a standard deviation of less than 0.3% and wavelength stability of better than 5 pm were achieved. The laser enables excitation of different semiconductor quantum dots and excitation schemes, essential for versatile easy-to-use single-photon sources based on quantum dots for research applications and commercial quantum computing.

Stimulated Raman scattering (SRS) microscopy is a powerful tool for in vivo diagnostic imaging due to the chemically-selective and label-free nature of the Raman process. In contrast to coherent anti-Stokes Raman scattering (CARS) SRS is often described as being background-free, although the SRS process can suffer from parasitic effects such as cross-phase modulation, two-photon absorption and thermal lensing with according distortion of the SRS signal and a corresponding reduction of the image contrast [1].

We present our recent developments in utilizing a compact and portable light source for high-speed multicolor stimulated Raman scattering imaging (SRS) in biomedical and medical environments. The source combines a rapid and wide tunability for accessing Raman bands between 700 and 3300 cm-1 with high stability in terms of power (deviation < 0.3 %) and wavelength (deviation < 0.5 pm) over more than 100 h. We were able to shorten the Stokes pulse duration to below 3ps, resulting in a twofold increase in SRS signal intensity compared to our previous version (7ps).

We present our recent developments in utilizing a compact and portable light source for high-speed multicolor stimulated Raman scattering imaging (SRS) in biomedical and medical environments. The source combines a rapid and wide tunability for accessing Raman bands between 700 and 3300 cm-1 with high stability in terms of power (deviation < 0.3 %) and wavelength (deviation < 0.5 pm) over more than 100 h. We were able to shorten the Stokes pulse duration to below 3ps, resulting in a twofold increase in SRS signal intensity compared to our previous version (7ps).