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Purpose: Raman spectroscopy (RS) is a promising method for brain tumor detection. Near-infrared autofluorescence (AF) acquired during RS provides additional useful information for tumor identification and was investigated in comparison with RS for delineating brain tumors in situ., Methods: Raman spectra were acquired together with AF in situ within the solid tumor and at the tumor border during routine brain tumor surgeries (218 spectra; glioma WHO II-III, n = 6; GBM, n = 10; metastases, n = 10; meningioma, n = 3). Tissue classification for tumor identification in situ was trained on ex vivo data (375 spectra; glioma/GBM patients, n = 20; metastases, n = 11; meningioma, n = 13; and epileptic hippocampi, n = 4)., Results: Both in situ and ex vivo data showed that AF intensity in brain tumors was lower than that in border regions and normal brain tissue. Moreover, a positive correlation was observed between the AF intensity and the intensity of the Raman band corresponding to lipids at 1437 cm - 1 , while a negative correlation was found with the intensity of the protein band at 1260 cm - 1 . The classification of in situ AF and RS datasets matched the surgeon's evaluation of tissue type, with correct rates of 0.83 and 0.84, respectively. Similar correct rates were achieved in comparison to histopathology of tissue biopsies resected in selected measurement positions (AF: 0.80, RS: 0.83)., Conclusions: Spectroscopy was successfully integrated into existing neurosurgical workflows, and in situ spectroscopic data could be classified based on ex vivo data. RS confirmed its ability to detect brain tumors, while AF emerged as a competitive method for intraoperative tumor delineation., (© 2024. The Author(s).)

Purpose: Infrared (IR) spectroscopy has the potential for tumor delineation in neurosurgery. Previous research showed that IR spectra of brain tumors are generally characterized by reduced lipid-related and increased protein-related bands. Therefore, we propose the exploitation of these common spectral changes for brain tumor recognition., Methods: Attenuated total reflection IR spectroscopy was performed on fresh specimens of 790 patients within minutes after resection. Using principal component analysis and linear discriminant analysis, a classification model was developed on a subset of glioblastoma (n = 135) and non-neoplastic brain (n = 27) specimens, and then applied to classify the IR spectra of several types of brain tumors., Results: The model correctly classified 82% (517/628) of specimens as "tumor" or "non-tumor", respectively. While the sensitivity was limited for infiltrative glioma, this approach recognized GBM (86%), other types of primary brain tumors (92%) and brain metastases (92%) with high accuracy and all non-tumor samples were correctly identified., Conclusion: The concept of differentiation of brain tumors from non-tumor brain based on a common spectroscopic tumor signature will accelerate clinical translation of infrared spectroscopy and related technologies. The surgeon could use a single instrument to detect a variety of brain tumor types intraoperatively in future clinical settings. Our data suggests that this would be associated with some risk of missing infiltrative regions or tumors, but not with the risk of removing non-tumor brain., (© 2022. The Author(s).)

Objective To determine the value of apparent diffusion coefficient (ADC) histogram parameters for the prediction of individual survival in patients undergoing surgery for recurrent glioblastoma (GBM) in a retrospective cohort study. Methods Thirty-one patients who underwent surgery for first recurrence of a known GBM between 2008 and 2012 were included. The following parameters were collected: age, sex, enhancing tumor size, mean ADC, median ADC, ADC skewness, ADC kurtosis and fifth percentile of the ADC histogram, initial progression free survival (PFS), extent of second resection and further adjuvant treatment. The association of these parameters with survival and PFS after second surgery was analyzed using log-rank test and Cox regression. Results Using log-rank test, ADC histogram skewness of the enhancing tumor was significantly associated with both survival (p = 0.001) and PFS after second surgery (p = 0.005). Further parameters associated with prolonged survival after second surgery were: gross total resection at second surgery (p = 0.026), tumor size (0.040) and third surgery (p = 0.003). In the multivariate Cox analysis, ADC histogram skewness was shown to be an independent prognostic factor for survival after second surgery. Conclusion ADC histogram skewness of the enhancing lesion, enhancing lesion size, third surgery, as well as gross total resection have been shown to be associated with survival following the second surgery. ADC histogram skewness was an independent prognostic factor for survival in the multivariate analysis.

Inactivating germline mutations of the novel putative tumor-suppressor gene LKB1/STK11 at 19p13.3 have been shown to cause Peutz-Jeghers syndrome (PJS), an autosomal dominantly inherited disease characterized by a predisposition to mucocutaneous pigmentations, as well as various benign and malignant neoplasms. To elucidate the role of LKB1/STK11 in the carcinogenesis of primary and secondary human brain tumors, a total of 309 tumors were analyzed for loss of heterozygosity (LOH) at microsatellite loci D19S886, DI9S878, and D19S565. Low LOH rates were observed for glioma (17.3%, n = 139), meningioma (5.3%, n = 57), schwannoma (0%, n = 21), pituitary adenoma (18.8%, n = 16), primary CNS lymphoma, neuroblastoma, plasmocytoma, medulloblastoma, germinoma, and papilloma of the choroid plexus (6.6%, n = 15). In contrast, brain metastases exhibited a mean LOH frequency of 42.6% (n = 61), with breast (56.3%) and lung cancer metastases (58.3%) being most frequently affected. Genomic DNA sequencing of the complete coding region of LKB1/STK11 was performed in all brain metastases exhibiting LOH (n = 26); no mutation was revealed, but we did find a germline mutation in a PJS patient. Despite high LOH fiequencies at the 19p13.3 locus in carcinoma metastases to the brain and occasional mutations reported for certain primary carcinomas, there are no mutations in LKB1/STK11. This fact suggests that alterations of LKB1/STK11 occur relatively early in tumorigenesis and are rarely involved in the development of carcinoma metastases. Based on these findings, the genes adjacent to LKB1/STK11 may be relevant for the development of metastases to the brain from certain carcinomas.