Dielectric Spectroscopy Shows a Permittivity Contrast between Meningioma Tissue and Brain White and Gray Matter-A Potential Physical Biomarker for Meningioma Discrimination.

The effectiveness of surgical resection of meningioma, the most common primary CNS tumor, depends on the capability to intraoperatively discriminate between the meningioma tissue and the surrounding brain white and gray matter tissues. Aiming to find a potential biomarker based on tissue permittivity, dielectric spectroscopy of meningioma, white matter, and gray matter ex vivo tissues was performed using the open-ended coaxial probe method in the microwave frequency range from 0.5 to 18 GHz. The averages and the 95% confidence intervals of the measured permittivity for each tissue were compared. The results showed the absence of overlap between the 95% confidence intervals for meningioma tissue and for brain white and gray matter, indicating a significant difference in average permittivity (p ≤ 0.05) throughout almost the entire measured frequency range, with the most pronounced contrast found between 2 GHz and 5 GHz. The discovered contrast is relevant as a potential physical biomarker to discriminate meningioma tissue from the surrounding brain tissues by means of permittivity measurement, e.g., for intraoperative meningioma margin assessment. The permittivity models for each tissue, developed in this study as its byproducts, will allow more accurate electromagnetic modeling of brain tumor and healthy tissues, facilitating the development of new microwave-based medical devices and tools.

Complex Permittivity of Ex-Vivo Human, Bovine and Porcine Brain Tissues in the Microwave Frequency Range.

Accurate knowledge about the dielectric properties of biological tissues in the microwave frequency range may lead to advancement of biomedical applications based on microwave technology. However, the published data are very scarce, especially for human brain tissues. The aim of this work was to measure and report the complex permittivity of brain white matter, grey matter and cerebellum. Complex permittivity was measured on human, bovine and porcine brain tissues in the microwave frequency range from 0.5 to 18 GHz using an open-ended coaxial probe. The results present a valuable addition to the available data on the brain tissue complex permittivity. Some noticeable variations between the results lead to several conclusions. Complex permittivity variation within the same tissue type of the individual species was comparable to interspecies variation. The difference was prominent between human brains obtained from autopsies, while bovine brains obtained from healthy animals showed very similar complex permittivity. We hypothesize that the difference might have been caused by the basic pathologies of the patients, where the associated therapies could have affected the brain water content. We also examined the effect of excised tissue degradation on its complex permittivity over the course of three days, and the results suggest the gradual dehydration of the samples.

Malignant brain neoplasms incidence and mortality trends in Croatia from 2001 to 2014.

AIM: To analyze the sex-specific incidence and mortality trends of brain malignancies in Croatia from 2001 to 2014. METHODS: Incidence and mortality rates per 100000 population were calculated using data obtained from the Croatian National Cancer Registry and the Croatian Bureau of Statistics. Rates were age-standardized to the European Standard Population, and trends were assessed using joinpoint regression. RESULTS: In the observed period there were 6634 new brain malignancy cases (52% men) and 5379 deaths due to this diagnosis (52% men). Age-standardized incidence rates ranged from 9.2-11.5 per 100000 in men and from 7-8.8 per 100000 in women. Mortality rates ranged from 7.5-8.7 per 100 000 in men and from 5-6.5 in women. Incidence trends in men, mortality in men, and mortality in women were not statistically significant, while a significant trend was observed in incidence in women (annual percent change -1.5; 95% confidence interval -2.3 to -0.6). No joinpoints were observed in any of the joinpoint analyses by sex for incidence and mortality. Age-specific incidence and mortality rates in both sexes indicate a trend shift toward older age. The proportion of morphologically verified cases ranged from 40.2%-62.4% in men and from 38.6%-56.3% in women; the proportion of death-certificate-only cases ranged from 3.3%-9.4% in men and from 3.3%-17.5% in women. CONCLUSION: Incidence and mortality of brain malignancies in Croatia are among the highest in Europe, while reporting on brain malignancies is still poor. There is a need for improved care of patients with brain malignancies and detailed and accurate data reporting.