Terahertz spectroscopy of gelatin-embedded human brain gliomas of different grades: a road toward intraoperative THz diagnosis

Abstract

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 grosstotal resection.

Investigation of Fresh Gastric Normal and Cancer Tissues Using Terahertz Time-Domain Spectroscopy

“…Basically, cancer and normal tissues could be well-distinguished by absorption coefficient only in Case 3 (Figure 5j). The strong deviation of absorption coefficient sometimes occurred when investigating fresh biological tissues by the THz time-domain spectroscopy, which was also obtained by other authors [22][23][24]. On the other hand, the difference between cancer and normal tissues was clearly seen by the refractive index in all cases, except Case 1 (Figure 5c), where cancer and serosa were distinguishable only above 0.6 THz.…”

“…Since increased water content is a symptom of many diseases, it is possible to confuse them with cancer during THz diagnosis. In [22], the authors did not find the difference in gelatin-embedded human brain gliomas with different World Health Organization (WHO) grades and edematous tissues in the brain. Additionally, the morphology of squamous cell carcinomas (SCC) and basal cell carcinomas (BCC) was not distinguished by THz imaging, unlike optical imaging that accurately presents the morphological features [28].…”

“…This difference could be explained by the high cell density in cancer regions [5], features of the tumor microenvironment that cause profound metabolic changes in the cells [26,27], abnormal protein density alterations, and the increase in the vasculature [27]. However, one of the main factors affecting the THz response from fresh biological tissue is an increased water content in tumors in comparison to normal tissues [8,22]. As seen in Figure 3, values and relations of dispersions of refractive indices and absorption coefficients might vary slightly in different cases, this could be explained by the changing water concentration in the samples that depend on the individual particularity of different patients as well as other factors, such as the difference in time during which the samples were in the NaCl saline.…”

“…Nevertheless, cancer is well distinguishable from, both, mucosa and serosa, which is the main requirement in an intraoperative diagnosis of malignant neoplasms. In future works we are planning to investigate THz response of various types of fresh gastric tissues, specifically, by conducting more statistical analyses, reducing the tissue dehydration by gelatin embedding [31], as well as using theories that introduce an inhomogeneous nature of biological tissues [22].…”

Температурная эволюция диэлектрического отклика alpha-лактозы моногидрата в терагерцовом диапазоне частот

“…он определяет низкочастотную границу применимости данных метода ТГц импульсной спектроскопии для численного анализа результатов. С учетом всех особенностей схемы измерения [27,28] следует ограничиться частотой около 10 cm −1 (300 GHz), ниже которой возможны существенные ошибки в установлении характера диэлектрической дисперсии вещества. Нагрев образца приводит не только к количественным, но и к качественным изменениям в спектрах, что указывает на происходящие в нем структурные изменения.…”