Arterial spin labelling MRI for brain tumour surveillance:do we really need cerebral blood flow maps?

Objectives: Arterial spin labelling (ASL) perfusion MRI is one of the available advanced MRI techniques for brain tumour surveillance. The first aim of this study was to investigate the correlation between quantitative cerebral blood flow (CBF) and non-quantitative perfusion weighted imaging (ASL-PWI) measurements. The second aim was to investigate the diagnostic accuracy of ASL-CBF and ASL-PWI measurements as well as visual assessment for identifying tumour progression. Methods: A consecutive cohort of patients who underwent 3-T MRI surveillance containing ASL for treated brain tumours was used. ROIs were drawn in representative parts of tumours in the ASL-CBF maps and copied to the ASL-PWI. ASL-CBF ratios and ASL-PWI ratios of the tumour ROI versus normal appearing white matter (NAWM) were correlated (Pearson correlation) and AUCs were calculated to assess diagnostic accuracy. Additionally, lesions were visually classified as hypointense, isointense, or hyperintense. We calculated accuracy at two thresholds: low threshold (between hypointense-isointense) and high threshold (between isointense-hyperintense). Results: A total of 173 lesions, both enhancing and non-enhancing, measured in 115 patients (93 glioma, 16 metastasis, and 6 lymphoma) showed a very high correlation of 0.96 (95% CI: 0.88–0.99) between ASL-CBF ratios and ASL-PWI ratios. AUC was 0.76 (95%CI: 0.65–0.88) for ASL-CBF ratios and 0.72 (95%CI: 0.58–0.85) for ASL-PWI ratios. Diagnostic accuracy of visual assessment for enhancing lesions was 0.72. Conclusion: ASL-PWI ratios and ASL-CBF ratios showed a high correlation and comparable AUCs; therefore, quantification of ASL-CBF could be omitted in these patients. Visual classification had comparable diagnostic accuracy to the ASL-PWI or ASL-CBF ratios. Clinical relevance statement: This study shows that CBF quantification of ASL perfusion MRI could be omitted for brain tumour surveillance and that visual assessment provides the same diagnostic accuracy. This greatly reduces the complexity of the use of ASL in routine clinical practice. Key Points: • Arterial spin labelling MRI for clinical brain tumour surveillance is undervalued and underinvestigated. • Non-quantitative and quantitative arterial spin labelling assessments show high correlation and comparable diagnostic accuracy. • Quantification of arterial spin labelling MRI could be omitted to improve daily clinical workflow.</p

Longitudinal characteristics of T2-FLAIR mismatch in IDH-mutant astrocytomas: Relation to grade, histopathology, and overall survival in the GLASS-NL cohort.

BACKGROUND: The T2-FLAIR mismatch sign is defined by signal loss of the T2-weighted hyperintense area with Fluid-Attenuated Inversion Recovery (FLAIR) on magnetic resonance imaging, causing a hypointense region on FLAIR. It is a highly specific diagnostic marker for IDH-mutant astrocytoma and is postulated to be caused by intercellular microcystic change in the tumor tissue. However, not all IDH-mutant astrocytomas show this mismatch sign and some show the phenomenon in only part of the lesion. The aim of the study is to determine whether the T2-FLAIR mismatch phenomenon has any prognostic value beyond initial noninvasive molecular diagnosis. METHODS: Patients initially diagnosed with histologically lower-grade (2 or 3) IDH-mutant astrocytoma and with at least 2 surgical resections were included in the GLASS-NL cohort. T2-FLAIR mismatch was determined, and the growth pattern of the recurrent tumor immediately before the second resection was annotated as invasive or expansive. The relation between the T2-FLAIR mismatch sign and tumor grade, microcystic change, overall survival (OS), and other clinical parameters was investigated both at first and second resection. RESULTS: The T2-FLAIR mismatch sign was significantly related to Grade 2 (80% vs 51%), longer post-resection median OS (8.3 vs 5.2 years), expansive growth, and lower age at second resection. At first resection, no relation was found between the mismatch sign and OS. Microcystic change was associated with areas of T2-FLAIR mismatch. CONCLUSIONS: T2-FLAIR mismatch in IDH-mutant astrocytomas is correlated with microcystic change in the tumor tissue, favorable prognosis, and Grade 2 tumors at the time of second resection

Longitudinal characteristics of T2-FLAIR mismatch in IDH-mutant astrocytomas: Relation to grade, histopathology, and overall survival in the GLASS-NL cohort

BACKGROUND: The T2-FLAIR mismatch sign is defined by signal loss of the T2-weighted hyperintense area with Fluid-Attenuated Inversion Recovery (FLAIR) on magnetic resonance imaging, causing a hypointense region on FLAIR. It is a highly specific diagnostic marker for IDH-mutant astrocytoma and is postulated to be caused by intercellular microcystic change in the tumor tissue. However, not all IDH-mutant astrocytomas show this mismatch sign and some show the phenomenon in only part of the lesion. The aim of the study is to determine whether the T2-FLAIR mismatch phenomenon has any prognostic value beyond initial noninvasive molecular diagnosis. METHODS: Patients initially diagnosed with histologically lower-grade (2 or 3) IDH-mutant astrocytoma and with at least 2 surgical resections were included in the GLASS-NL cohort. T2-FLAIR mismatch was determined, and the growth pattern of the recurrent tumor immediately before the second resection was annotated as invasive or expansive. The relation between the T2-FLAIR mismatch sign and tumor grade, microcystic change, overall survival (OS), and other clinical parameters was investigated both at first and second resection. RESULTS: The T2-FLAIR mismatch sign was significantly related to Grade 2 (80% vs 51%), longer post-resection median OS (8.3 vs 5.2 years), expansive growth, and lower age at second resection. At first resection, no relation was found between the mismatch sign and OS. Microcystic change was associated with areas of T2-FLAIR mismatch. CONCLUSIONS: T2-FLAIR mismatch in IDH-mutant astrocytomas is correlated with microcystic change in the tumor tissue, favorable prognosis, and Grade 2 tumors at the time of second resection

Estudi de la influència del perfil dels àcids grassos sobre les propietats d'emulsions estabilitzades amb cel·lulosa bacteriana

[ES] Una de las aplicaciones de la celulosa bacteriana que actualmente está llamando la atención es su uso como agente estabilizador de emulsiones. Este proyecto analiza cómo la estructura de los ácidos grasos del aceite que forma la emulsión afecta a la estabilidad creada por la celulosa bacteriana. Se preparan cuatro tipos de emulsiones de aceite en agua con diferente composición de ácidos grasos (aceite de canola, aceite de oliva, aceite de coco y manteca de cerdo) mediante la técnica de sonicación y se compara el efecto estabilizador de la celulosa bacteriana en cada uno mediante varios métodos, incluida la microscopía. y herramientas analíticas. Los resultados obtenidos muestran que los ácidos grasos insaturados de cadena larga contribuyen a una mayor estabilidad de la emulsión, mientras que las grasas sólidas con cadenas más cortas muestran el peor comportamiento en cuanto a estabilidad, aunque la celulosa bacteriana parece evitar que las grasas se oxiden durante el almacenamiento. Si bien es probable que las emulsiones de aceite líquido estabilizadas con celulosa bacteriana desempeñen un papel importante en la industria alimentaria, las emulsiones de grasa sólida resistentes a la oxidación tienen un potencial notable en los cosméticos de larga duración.[EN] One of the applications of bacterial cellulose that is currently raising attention is its use as an emulsion stabilizing agent. This project analyzes how the structure of the fatty acids in the oil forming the emulsion affects the stability created by bacterial cellulose. Four types of oil-in-water emulsions with different fatty acids composition (canola oil, olive oil, coconut oil and pork lard) are prepared using the sonication technique and the stabilizing effect of bacterial cellulose in each one is compared by various methods including microscopy and analytical tools. The results obtained show that long-chained unsaturated fatty acids contribute to higher emulsion stability, while solid fats with shorter chains show the worst performance as to stability, although bacterial cellulose seems to prevent the fats from oxidation during storage. While liquid oil emulsions stabilized with bacterial cellulose are likely to play an important role in the food industry, oxidation-resistant solid fat emulsions have a notable potential in long shelf-life cosmetics.Lavrova, A. (2022). Study of influence of fatty acid profile on properties of emulsions stabilized with bacterial cellulose. Universitat Politècnica de València. http://hdl.handle.net/10251/186311TFG

Stress level in beams with sinusoidal perforation

The problem of determining of stress state in beams with sinusoidal perforation under concentrated force was considered. An empirical expression has been obtained for the stress distribution in dependence on parameters of perforation and force factors – bending moment and shear force. Von Mises equivalent stresses near the edge of openings is presented by the sum of two items caused by two types of deformations – shear and bending. The numerical coefficients of this dependence were determined with help of the finite element method calculations. The obtained empirical relation was verified by FEM calculations using the ANSYS software. It was studied effect of the fillet radius in corners of openings on stress state of beams with sinusoidal perforation in wide range of relative height of openings. Obtained results allow to conclude that calculation of equivalent stresses in beams with sinusoidal perforation bring to divergence not exceeding 5%

MODELING OF LOCAL BUCKLING OF PERFORATED BEAMS WITH CIRCULAR OPENINGS: COMPUTATION BY FEM AND EXPERIMENTS ON TIN-PLATE STRUCTURES

Subject: investigation of local stability of cellular beams with circular openings, which are widely used in civil engineering. The main problem in this field is the absence of analytical relations for evaluation of critical load of perforated beams. Research objectives: show effectiveness of studying the local stability of perforated beams on small-scale models made of tin; obtain a relationship for recalculating the results of the model tests onto the full-scale structure; check the reliability of numerical calculations of the critical load by the finite element method (FEM). Materials and methods: tests were performed on the tin models of small beams of 32 cm length and on the full-scale steel structure of 4 m length. As for research methods, we used similarity theory, experiments and numerical modeling of stability by the finite element method with help of the software package ANSYS. Results: it was shown that the tests of small-scale models give reliable results for estimation of critical load for full-scale structures that experience local buckling in elastic stage of loading. Obtained relationship for recalculation of critical load of the model onto the full-scale structure does not require strict observance of similarity with respect to Poisson’s ratio and size of flanges because their influence on the critical load is small. Comparison of data obtained from the model tests with the results of structure analysis by the finite element method showed that FEM calculations give reliable results for prediction of stability, and the testing of models is needed only for examining the effect of initial imperfections in the form of small buckles, inaccuracy of manufacture or variation in thicknesses, or the influence of residual stresses due to welding. Discrepancy between the results of tests of the models and numerical calculations of the critical load by FEM does not exceed 6 %. Conclusions: the relationship obtained on the basis of similarity theory allows us to efficiently recalculate the critical load of the model onto the full-scale structure, for which only similarity of geometry of the perforated web from the side view, identity of boundary conditions and the loading type should be respected. Critical load of the cellular beam is proportional to the cube of the web thickness

Detection of cyber threats to network infrastructure of digital production based on the methods of Big Data and multifractal analysis of traffica

The article offers an approach to analyzing data security of network infrastructure of digital production providing for contraction of network traffic size and detecting anomalies in the network traffic on the basis of multifractal analysis. The contraction of data size will be provided due to extraction of significant parameters from the network packets and dropping the rest data, as well as due to application of such Big Data method as aggregation. The experimental investigations on contracting data size on analyzing security have proven the operability and efficiency thereof. The method of contracting data size has demonstrated a possibility of traffic volume contraction from hundreds of Gbit to several Mbyte. The suggested approach to security analysis using the assessment of width of multifractional spectrum as a criterion of anomaly presence has detected both simulated attacks of denial of servicing SYN-flood and smurf. Thus, the suggested approach can be efficiently used for analyzing big volumes of dissimilar traffic of network infrastructure of digital production

Wavelet-analysis of network traffic time-series for detection of attacks on digital production infrastructure

Digital production integrates with all the areas of human activity including critical industries, therefore the task of detecting network attacks has a key priority in protecting digital manufacture systems. This article offers an approach for analysis of digital production security based on evaluation of a posteriori probability for change point in time-series, which are based on the change point coefficient values of digital wavelet-transform in the network traffic time-series. These time-series make it possible to consider the network traffic from several points of view at the same time, which plays an important role in the task of detecting network attacks. The attack methods vary significantly; therefore, in order to detect them it is necessary to monitor different values of various traffic parameters. The proposed method has demonstrated its efficiency in detecting network service denial attacks (SlowLoris and HTTP DoS) being realized at the application level

Detection of cyber threats to network infrastructure of digital production based on the methods of Big Data and multifractal analysis of traffic

The article offers an approach to analyzing data security of network infrastructure of digital production providing for contraction of network traffic size and detecting anomalies in the network traffic on the basis of multifractal analysis. The contraction of data size will be provided due to extraction of significant parameters from the network packets and dropping the rest data, as well as due to application of such Big Data method as aggregation. The experimental investigations on contracting data size on analyzing security have proven the operability and efficiency thereof. The method of contracting data size has demonstrated a possibility of traffic volume contraction from hundreds of Gbit to several Mbyte. The suggested approach to security analysis using the assessment of width of multifractional spectrum as a criterion of anomaly presence has detected both simulated attacks of denial of servicing SYN-flood and smurf. Thus, the suggested approach can be efficiently used for analyzing big volumes of dissimilar traffic of network infrastructure of digital production