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Item Intraoperative assessment of tumor margins during glioma resection by desorption electrospray ionization-mass spectrometry(National Academy of Sciences, 2017-06-27) Pirro, Valentina; Alfaro, Clint M.; Jarmusch, Alan K.; Hattab, Eyas M.; Cohen-Gadol, Aaron A.; Cooks, R. Graham; Pathology and Laboratory Medicine, School of MedicineGliomas infiltrate into surrounding healthy brain tissue. Microsurgical resection aims for maximal tumor resection while minimizing morbidity. Surgical margins are defined based on the surgeon’s experience, visual observation, and neuronavigation. Surgical margin assessment is rarely undertaken intraoperatively due to time constraints and unreliability of such evaluation. Routine, pathologic intraoperative examination provides no molecular information. Molecular measurements using mass spectrometry can be made rapidly on tissue during surgery to identify tissue types, estimate tumor infiltration, and recognize the presence of prognostic mutations by monitoring oncometabolites and phospholipids. This intraoperative study demonstrates the power of mass spectrometry in assessing diagnostic and prognostic information on discrete surgeon-defined points along the resection margins to improve tumor resection, even in regions without MRI contrast enhancement., Intraoperative desorption electrospray ionization-mass spectrometry (DESI-MS) is used to characterize tissue smears by comparison with a library of DESI mass spectra of pathologically determined tissue types. Measurements are performed in the operating room within 3 min. These mass spectra provide direct information on tumor infiltration into white or gray brain matter based on N-acetylaspartate (NAA) and on membrane-derived complex lipids. The mass spectra also indicate the isocitrate dehydrogenase mutation status of the tumor via detection of 2-hydroxyglutarate, currently assessed postoperatively on biopsied tissue using immunohistochemistry. Intraoperative DESI-MS measurements made at surgeon-defined positions enable assessment of relevant disease state of tissue within the tumor mass and examination of the resection cavity walls for residual tumor. Results for 73 biopsies from 10 surgical resection cases show that DESI-MS allows detection of glioma and estimation of high tumor cell percentage (TCP) at surgical margins with 93% sensitivity and 83% specificity. TCP measurements from NAA are corroborated by indirect measurements based on lipid profiles. Notably, high percentages (>50%) of unresected tumor were found in one-half of the margin biopsy smears, even in cases where postoperative MRI suggested gross total tumor resection. Unresected tumor causes recurrence and malignant progression, as observed within a year in one case examined in this study. These results corroborate the utility of DESI-MS in assessing surgical margins for maximal safe tumor resection. Intraoperative DESI-MS analysis of tissue smears, ex vivo, can be inserted into the current surgical workflow with no alterations. The data underscore the complexity of glioma infiltration.Item Neurosurgical Flexible Probe Microscopy with Enhanced Architectural and Cytological Detail(Elsevier, 2019-08) Osman, Hany; Elsahy, Deena; Slivova, Veronika; Thompson, Corey; Georges, Joseph; Yocom, Steven; Cohen-Gadol, Aaron A.; Neurological Surgery, School of MedicineBackground Microscopic delineation and clearance of tumor cells at neurosurgical excision margins potentially reduce tumor recurrence and increase patient survival. Probe-based in vivo fluorescence microscopy technologies are promising for neurosurgical in vivo microscopy. Objective We sought to demonstrate a flexible fiberoptic epifluorescence microscope capable of enhanced architectural and cytological imaging for in vivo microscopy during neurosurgical procedures. Methods Eighteen specimens were procured from neurosurgical procedures. These specimens were stained with acridine orange and imaged with a 3-dimensional (3D)-printed epifluorescent microscope that incorporates a flexible fiberoptic probe. Still images and video sequence frames were processed using frame alignment, signal projection, and pseudo-coloring, resulting in resolution enhancement and an increased field of view. Results Images produced displayed good nuclear contrast and architectural detail. Grade 1 meningiomas demonstrated 3D chords and whorls. Low-grade meningothelial nuclei showed streaming and displayed regularity in size, shape, and distribution. Oligodendrogliomas showed regular round nuclei and a variably staining background. Glioblastomas showed high degrees of nuclear pleomorphism and disarray. Mitoses, vascular proliferation, and necrosis were evident. Conclusions We demonstrate the utility of a 3D-printed, flexible probe microscope for high-resolution microscopic imaging with increased architectural detail. Enhanced in vivo imaging using this device may improve our ability to detect and decrease microscopic tumor burden at excision margins during neurosurgical procedures.