The new approach to intraoperative navigation during glial brain tumors removal is presented. A combined method is proposed for simultaneous spectroscopic and video fluorescence analysis of the state of tissues in the destruction zone using the applied part performed in the form of a neurosurgical aspirator cannula. In the walls of the applied part there are tubular channels into which lighting and receiving optical fibers are integrated. At the end of the cannula, the channels for optical fibers are arranged so as to perform spectroscopic analysis in contact with the surface of the biological tissue, as well as video fluorescence analysis at the working distance to the surface of the tissue. The joint use of fiber-optic systems for recording the video stream and spectral dependences allows real-time assessment of the degree of pathological tissue changes in the field of view of the video system, which are also located in the aspiration zone, with the simultaneous quantification of diagnostically significant spectroscopic criteria. System testing was carried out on samples of human intracranial tumors obtained during neurosurgical operations. During the removal of a tumor from different sites (tumor center, perifocal area), the degree of in vivo fluorescence signal from the tumor site was determined intraoperatively using a Zeiss Opmi Pentero intraoperative microscope in Blue 400 mode. From the selected area of the tumor, biopsy material was taken (presumably homogeneous in its properties) with subsequent measurement of spectra and combined images using the developed device. A high correlation was shown between the level of the fluorescence signal recorded spectroscopically and the brightness of the fluorescence image in the endoscopic channel of the device. The level of the fluorescent signal showed a high correlation with the degree of malignancy of tissues according to the results of pathomorphological examination.
We applied reflection-mode terahertz (THz) pulsed spectroscopy to study ex vivo the optical properties of human brain tumors with the different World Health Organization grades, as well as of perifocal regions comprised of intact (healthy) and edematous tissues. We applied gelatin-embedding in order to fix freshly-excised tissues, thus, preserving them from hydration/dehydration and sustaining their THz response unaltered for a couple of hours after resection. We observed a contrast between the THz optical properties of intact tissues and tumors, including gliomas and meningiomas of the brain, in turn, the response of edematous tissues is close to that of a tumor. The observed contrast between intact tissues and tumors has an endogenous character and originates reportedly from increased water content in a tumor due to edema, abnormal vascularity and, in some cases, necrotic debris. The observed results justify a prospect of THz technology in the intraoperative label-free diagnosis of human brain tumors.
An intraoperative diagnosis of brain tumors is one of the most urgent and challenging problem of the modern neurosurgery. The most important measure of the effectiveness of treatment is the complete tumor resection. The existing methods of the intraoperative neurodiagnosis of tumors are plagued with limited sensitivity, especially for low-grade gliomas, and, furthermore, can remain rather expensive. The recently reported results of optical coherence tomography (OCT) application for finding differences between healthy and malignant tissues make it become one of the promising label-free diagnostic instruments. Nevertheless, the wide use of OCT in clinical practice is limited by the lack of complete study of its opportunities in neurosurgery, which leads to a huge scientific interest. Our research, aimed at the study of the ability of OCT for the intraoperative diagnosis of brain gliomas of different grades, has the goal to observe the differences between OCT signals obtained for ex vivo samples of various types of human brain glioma and intact brain tissue. We propose a 3D-feature based data analysis that demonstrates promising results in differentiation of tissue classes.
The problem of complete resection of human brain glioma during neurosurgery is still one of the most challenging, since the existed diagnostic methods are plagued with limited sensitivity and specificity; they remain laborious, time-consuming and/or rather expensive. The present work includes the ex vivo study of malignant brain gliomas featuring different grades (according to the World Health Organization) by means of two methods, i.e. optical coherence tomography (OCT) and terahertz pulsed spectroscopy (TPS). Both OCT and TPS studies were done just after the tissue resection and included gelatin embedding of the samples for conservation of water content. The further histological examination using hematoxylin and eosin (H&E) stained microscopy approved the diagnosis. The results demonstrate the potential of TPS to differentiate intact and malignant tissues and the potential of OCT to differentiate low- and high-grade gliomas as well as intact tissue and low-grade gliomas. Thus, combination of these modalities seems to be rather prospective for the further development of the advanced intraoperative diagnostic tools.
Intraoperative diagnosis of brain tumors remains a challenging problem of modern neurosurgery. A complete resection of tumor is the most important factor, determining an efficiency of its treatment, while an incomplete resection, caused by inaccurate detection of tumor margins, increases a probability of the tumor recurrence. The existing methods of the intraoperative neurodiagnosis of tumors are plagued with limited sensitivity and specificity; they remain laborious, time-consuming and/or rather expensive. Therefore, the development of novel methods for the intraoperative diagnosis of gliomas relying on modern instruments of medical imaging is a topical problem of medicine, physics, and engineering. In our research, we studied the ability of dual-modality imaging that combines such methods as optical coherence tomography (OCT) and terahertz (THz) pulsed spectroscopy, for intraoperative diagnosis of brain tumors with a strong emphasize on a human brain gliomas. We performed experimental studies of the frequency-dependent THz dielectric properties and OCT imaging of healthy (intact) and pathological brain tissues ex vivo in order to analyze the prospect for differentiation between tissue classes. The observed results highlight a potential of the considered instruments in the label-free intraoperative neurodiagnostics.
We applied terahertz (THz)-pulsed spectroscopy to study ex vivo the refractive index and absorption coefficient of human brain gliomas featuring different grades, as well as perifocal regions containing both intact and edematous tissues. Glioma samples from 26 patients were considered and analyzed according to further histological examination. In order to fix tissues for the THz measurements, we applied gelatin embedding, which allows for sustaining their THz response unaltered, as compared to that of the freshly excised tissues. We observed a statistical difference between the THz optical constants of intact tissues and gliomas of grades I to IV, while the response of edema was similar to that of tumor. The results of this paper justify a potential of THz technology in the intraoperative label-free diagnosis of human brain gliomas for ensuring the gross-total resection.
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