Optical coherence tomography of the ex vivo human and rat brain tissue samples is performed. The analysis of attenuation coefficient, coefficient based on effective refractive index, and their standard deviations was obtained from OCT measurements.
In the paper, the double-Debye and double-overdamped-oscillator models are considered for parametrization of the terahertz (THz) dielectric response of human brain tissues. Experimental data can be accurately reproduced for the intact tissues and gliomas using both models. While the double-Debye dielectric model is widely used in THz biophotonics, the double-overdamped-oscillator model appears to be more physically rigorous, since it satisfies the sum rule. In our opinion, the described double-overdamped-oscillator model is important for further research and development in THz biophotonics and neurodiagnosis of tumors.
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.
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.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.