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Purpose: Analysis of autofluorescence holds promise for brain tumor delineation and diagnosis. Therefore, we investigated the potential of a commercial confocal laser scanning endomicroscopy (CLE) system for clinical imaging of brain tumors., Methods: A clinical CLE system with fiber probe and 488 nm laser excitation was used to acquire images of tissue autofluorescence. Fresh samples were obtained from routine surgeries (glioblastoma n = 6, meningioma n = 6, brain metastases n = 10, pituitary adenoma n = 2, non-tumor from surgery for the treatment of pharmacoresistant epilepsy n = 2). Additionally, in situ intraoperative label-free CLE was performed in three cases. The autofluorescence images were visually inspected for feature identification and quantification. For reference, tissue cryosections were prepared and further analyzed by label-free multiphoton microscopy and HE histology., Results: Label-free CLE enabled the acquisition of autofluorescence images for all cases. Autofluorescent structures were assigned to the cytoplasmic compartment of cells, elastin fibers, psammoma bodies and blood vessels by comparison to references. Sparse punctuated autofluorescence was identified in most images across all cases, while dense punctuated autofluorescence was most frequent in glioblastomas. Autofluorescent cells were observed in higher abundancies in images of non-tumor samples. Diffuse autofluorescence, fibers and round fluorescent structures were predominantly found in tumor tissues., Conclusion: Label-free CLE imaging through an approved clinical device was able to visualize the characteristic autofluorescence patterns of human brain tumors and non-tumor brain tissue ex vivo and in situ. Therefore, this approach offers the possibility to obtain intraoperative diagnostic information before resection, importantly independent of any kind of marker or label., Competing Interests: Declarations. Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

Background: Infrared (IR) spectroscopy allows intraoperative, optical brain tumor diagnosis. Here, we explored it as a translational technology for the identification of aggressive meningioma types according to both, the WHO CNS grading system and the methylation classes (MC)., Methods: Frozen sections of 47 meningioma were examined by IR spectroscopic imaging and different classification approaches were compared to discern samples according to WHO grade or MC., Results: IR spectroscopic differences were more pronounced between WHO grade 2 and 3 than between MC intermediate and MC malignant, although similar spectral ranges were affected. Aggressive types of meningioma exhibited reduced bands of carbohydrates (at 1024 cm -1 ) and nucleic acids (at 1080 cm -1 ), along with increased bands of phospholipids (at 1240 and 1450 cm -1 ). While linear discriminant analysis was able to discern spectra of WHO grade 2 and 3 meningiomas (AUC 0.89), it failed for MC (AUC 0.66). However, neural network classifiers were effective for classification according to both WHO grade (AUC 0.91) and MC (AUC 0.83), resulting in the correct classification of 20/23 meningiomas of the test set., Conclusions: IR spectroscopy proved capable of extracting information about the malignancy of meningiomas, not only according to the WHO grade, but also for a diagnostic system based on molecular tumor characteristics. In future clinical use, physicians could assess the goodness of the classification by considering classification probabilities and cross-measurement validation. This might enhance the overall accuracy and clinical utility, reinforcing the potential of IR spectroscopy in advancing precision medicine for meningioma characterization., Competing Interests: None., (© The Author(s) 2024. Published by Oxford University Press, the Society for Neuro-Oncology and the European Association of Neuro-Oncology.)

As the state of resection margins is an important prognostic factor after extirpation of colorectal liver metastases, surgeons aim to obtain negative margins, sometimes elaborated by resections of the positive resection plane after intraoperative frozen sections. However, this is time consuming and results sometimes remain unclear during surgery. Label-free multimodal multiphoton microscopy (MPM) is an optical technique that retrieves morpho-chemical information avoiding all staining and that can potentially be performed in real-time. Here, we investigated colorectal liver metastases and hepatic tissue using a combination of three endogenous nonlinear signals, namely: coherent anti-Stokes Raman scattering (CARS) to visualize lipids, two-photon excited fluorescence (TPEF) to visualize cellular patterns, and second harmonic generation (SHG) to visualize collagen fibers. We acquired and analyzed over forty thousand MPM images of metastatic and normal liver tissue of 106 patients. The morphological information with biochemical specificity produced by MPM allowed discriminating normal liver from metastatic tissue and discerning the tumor borders on cryosections as well as formalin-fixed bulk tissue. Furthermore, automated tissue type classification with a correct rate close to 95% was possible using a simple approach based on discriminant analysis of texture parameters. Therefore, MPM has the potential to increase the precision of resection margins in hepatic surgery of metastases without prolonging surgical intervention., (© 2023. The Author(s).)

The elucidation of biomechanics furthers our understanding of brain tumour biology. Brillouin spectroscopy is a new optical method that addresses viscoelastic properties down to subcellular resolution in a contact-free manner. Moreover, it can be combined with Raman spectroscopy to obtain co-localized biochemical information. Here, we applied co-registered Brillouin and Raman spectroscopy to U87-MG human glioblastoma cells in vitro . Using two-dimensional and three-dimensional cultures, we related biomechanical properties to local biochemical composition at the subcellular level, as well as the cell phenotype. Brillouin and Raman mapping of adherent cells showed that the nucleus and nucleoli are stiffer than the perinuclear region and the cytoplasm. The biomechanics of the cell cytoplasm is affected by culturing conditions, i.e. cells grown as spheroids are stiffer than adherent cells. Inside the spheroids, the presence of lipid droplets as assessed by Raman spectroscopy revealed higher Brillouin shifts that are not related to a local increase in stiffness, but are due to a higher refractive index combined with a lower mass density. This highlights the importance of locally defined biochemical reference data for a correct interpretation of the Brillouin shift of cells and tissues in future studies investigating the biomechanics of brain tumour models by Brillouin spectroscopy.

1. The cerebral anlage of Agapornis roseicollis was investigated in serially cut slices during the developmental stages before hatching (day 3-day 20) by light microscopical quantitative and qualitative methods. 2. During earlier stages of development, the brain anlage is divided in three dorsally and four ventrally situated, longitudinally oriented matrix zones (D1-D3, V1-V4 according to Kuhlenbeck). In this developing system, mainly the lateral part of the telencephalic wall including its dorsal extension is considered to establish special importance for the further ontogenetic development. 3. The quite simple structure of the epistriatum in Reptils occurs as the neo-hyperstriatum-complex in Birds; likewise, deriving from the neocortex primitivus in Reptils, in Mammalia this part obviously develops to the more and more expanding neocortex as can be followed from lower mammalia species up to the highly developed Primates. According to the first main criterion of Remane, the homology of these parts of the brain in different vertebrates is most evident because these brain parts occupy exactly the same position in the brain anlage of early embryonal stages. 4. In Reptils, the neocortex primitivus appears as the last during ontogenetic development. Likewise in Birds, the neohyperstriatum-complex that is homologeous to the neocortex in Mammalia, differentiates during the final stages. These facts again emphasize the homology of these structures. 5. Further evidence for homology is obtained by the observation that in Agapornides the primordium of the neo-hyperstriatumcomplex contains migrating matrix cells columns, which also in Mammalia arrange into the same manner. Moreover, the transient and heterochronuous occurrence of cell layers at the outer surface of the brain anlage reminds to the development of palaeocortex and neocortex in Reptils and Mammalia. 6. From the point of view of evolution biology, the process of the progressive evolution is considered to be based on the step by step addition of tiny new structure-function-units to the already present morphology going along with a full structural and functional integration of the added, thus to achive the new quality. This so-called "Additive Morphogenesis" was effective during millions of years, consisting of such microevolutionary processes, and finally caused the "Gestaltungswandel", the ever changing evolving variety of bodily forms (and functions) that is recapitulated during individual species ontogenesis.