Cпектроскопия спонтанного комбинационного рассеяния для ex vivo диагностики внутричерепных опухолей

Neurosurgery of intracranial tumors, especially of glial origin, is a non-trivial task due to their infiltrative growth. In recent years, optical methods of intraoperative navigation have been actively used in neurosurgery. However, one of the most widely used approaches based on the selective accumulation of fluorescent contrast medium (5-ALA-induced protoporphyrin IX) by the tumor cannot be applied to a significant number of tumors due to its low accumulation. On the contrary, Raman spectroscopy, which allows analyzing the molecular composition of tissues while preserving all the advantages of the method of fluorescence spectroscopy, does not require the use of an exogenous dye and may become a method of choice when composing a system for intraoperative navigation or optical biopsy. This work presents the first results of using the principal component method to classify Raman spectra of human glioblastoma with intermediate processing of spectra to minimize possible errors from the fluorescence of both endogenous fluorophores and photosensitizers used in fluorescence navigation. As a result, differences were found in the principal component space, corresponding to tissue samples with microcystic components, extensive areas of necrosis, and foci of fresh hemorrhages. It is shown that this approach can serve as the basis for constructing a system for automatic intraoperative tissue classification based on the analysis of Raman spectra.Cпектроскопия спонтанного комбинационного рассеяния для ex vivo диагностики внутричерепных опухолей  Нейрохирургия внутричерепных опухолей, особенно глиального происхождения, представляет нетривиальную задачу в силу их инфильтративного роста. В последние годы в нейрохирургии активно используются оптические методы интраоперационной навигации, однако один из наиболее широко распространенных подходов, основанный на селективном накоплении опухолью флуоресцентного контрастного вещества (5-АЛК индуцированного протопорфирина IX), не может быть применен для значимой части опухолей вследствие его низкого накопления. Напротив, спектроскопия комбинационного рассеяния, позволяющая проводить анализ молекулярного состава тканей с сохранением всех достоинств метода флуоресцентной спектроскопии, не требует при этом введения экзогенного красителя и может быть вариантом выбора при построении системы интраоперационной навигации или оптической биопсии. В настоящей работе представлены первые результаты использования метода главных компонент для классификации спектров комбинационного рассеяния глиобластомы человека с промежуточной обработкой спектров для минимизации возможных ошибок от флуоресценции как эндогенных флуорофоров, так и фотосенсибилизаторов, используемых при флуоресцентной навигации. В результате были обнаружены различия в пространстве главных компонент, соответствующие образцам тканей с микрокистозными компонентами, обширными участками некрозов, фокусами свежих кровоизлияний. Показано, что данный подход может послужить основой для построения системы автоматической интраоперационной классификации тканей на основе анализа спектров комбинационного рассеяния

Predictive model for preoperative risk calculation of cerebrospinal fluid leak after resection of midline craniofacial mass lesions

Background: Complex anterior skull base defects produced by resection of mass lesions vary in size and configuration and may be extensive. We analyzed the largest single-center series of midline craniofacial lesions extending intra- and extracranially. The study aims at the development of a predictive model for preoperative measurement of the risk of the postoperative cerebrospinal fluid (CSF) leak based on patients' characteristics and surgical plans. Methods: 166 male and 149 female patients with mean age 40,5 years (1 year and – 81 years) operated for benign and tumor-like midline craniofacial mass lesions were retrospectively analyzed using logistic regression method (Ridge regression algorithm was selected). The overall CSF leak rate was 9.6%. The ROSE algorithm and ‘glmnet’ software suite in R were used to overcome the cohort's disbalance and avoid overtraining the model. Results: The most influential modifiable negative predictor of the postoperative CSF leak was the use of extracranial and combined approaches. Use of transbasal approaches, gross total resection, utilization of one or two vascularized flaps for skull base reconstruction were the foremost modifiable predictors of a good outcome. Criterium of elevated risk was established at 50% with a specificity of the model as high as 0.83. Conclusions: The performed study has allowed for identifying the most significant predictors of postoperative CSF leak and developing an effective formula to estimate the risk of this complication using data known for each patient. We believe that the suggested web-based online calculator can be helpful for decision making support in off-pattern clinical situations

One-step orbit reconstruction using PMMA implants following hyperostotic sphenoid wing meningioma removal: Evolution of the technique in short clinical series

Purpose: To report our experience with patient specific implants for one-step orbit reconstruction following hyperostotic SWM removal and to describe the evolution of the technique through three surgical cases. Methods: Three cases of one-step SWM removal and orbit reconstruction are described. All cases are given consecutively to describe the evolution of the technique. Hyperostotic bone resection was facilitated by electromagnetic navigation and cutting guides (templates). Based on a 3D model, silicone molds were made using CAD/CAM. Then PMMA implant was fabricated from these molds. The implant was adjusted and fixed to the cranium with titanium screws after tumor removal. Results: Following steps of the procedure changed over these series: hyperostotic bone resection, implant thickness control, implant overlay features, anatomic adjustments, implant fixation. The proptosis resolved in all cases. In one patient the progressive visual acuity deterioration was recognized during the follow-up. No oculomotor disturbances and no tumor regrowth were found at the follow-up. Conclusion: CAD/CAM technologies enable creation of implants of any size and configuration, and thereby, to increase the extent of bony resection and lower the risk of tumor progression. The procedure is performed in one step which decreases the risk of postoperative morbidity

Spontaneous Raman spectroscopy for intracranial tumors diagnostics ex vivo

Neurosurgery of intracranial tumors, especially of glial origin, is a non-trivial task due to their infiltrative growth. In recent years, optical methods of intraoperative navigation have been actively used in neurosurgery. However, one of the most widely used approaches based on the selective accumulation of fluorescent contrast medium (5-ALA-induced protoporphyrin IX) by the tumor cannot be applied to a significant number of tumors due to its low accumulation. On the contrary, Raman spectroscopy, which allows analyzing the molecular composition of tissues while preserving all the advantages of the method of fluorescence spectroscopy, does not require the use of an exogenous dye and may become a method of choice when composing a system for intraoperative navigation or optical biopsy. This work presents the first results of using the principal component method to classify Raman spectra of human glioblastoma with intermediate processing of spectra to minimize possible errors from the fluorescence of both endogenous fluorophores and photosensitizers used in fluorescence navigation. As a result, differences were found in the principal component space, corresponding to tissue samples with microcystic components, extensive areas of necrosis, and foci of fresh hemorrhages. It is shown that this approach can serve as the basis for constructing a system for automatic intraoperative tissue classification based on the analysis of Raman spectra