| 1. |
- Flannick, Jason, et al.
(author)
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Data Descriptor : Sequence data and association statistics from 12,940 type 2 diabetes cases and controls
- 2017
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In: Scientific Data. - : Springer Science and Business Media LLC. - 2052-4463. ; 4
-
Journal article (peer-reviewed)abstract
- To investigate the genetic basis of type 2 diabetes (T2D) to high resolution, the GoT2D and T2D-GENES consortia catalogued variation from whole-genome sequencing of 2,657 European individuals and exome sequencing of 12,940 individuals of multiple ancestries. Over 27M SNPs, indels, and structural variants were identified, including 99% of low-frequency (minor allele frequency [MAF] 0.1-5%) non-coding variants in the whole-genome sequenced individuals and 99.7% of low-frequency coding variants in the whole-exome sequenced individuals. Each variant was tested for association with T2D in the sequenced individuals, and, to increase power, most were tested in larger numbers of individuals (> 80% of low-frequency coding variants in similar to ~82 K Europeans via the exome chip, and similar to ~90% of low-frequency non-coding variants in similar to ~44 K Europeans via genotype imputation). The variants, genotypes, and association statistics from these analyses provide the largest reference to date of human genetic information relevant to T2D, for use in activities such as T2D-focused genotype imputation, functional characterization of variants or genes, and other novel analyses to detect associations between sequence variation and T2D.
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| 2. |
- Fuchsberger, Christian, et al.
(author)
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The genetic architecture of type 2 diabetes
- 2016
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In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 536:7614, s. 41-47
-
Journal article (peer-reviewed)abstract
- The genetic architecture of common traits, including the number, frequency, and effect sizes of inherited variants that contribute to individual risk, has been long debated. Genome-wide association studies have identified scores of common variants associated with type 2 diabetes, but in aggregate, these explain only a fraction of the heritability of this disease. Here, to test the hypothesis that lower-frequency variants explain much of the remainder, the GoT2D and T2D-GENES consortia performed whole-genome sequencing in 2,657 European individuals with and without diabetes, and exome sequencing in 12,940 individuals from five ancestry groups. To increase statistical power, we expanded the sample size via genotyping and imputation in a further 111,548 subjects. Variants associated with type 2 diabetes after sequencing were overwhelmingly common and most fell within regions previously identified by genome-wide association studies. Comprehensive enumeration of sequence variation is necessary to identify functional alleles that provide important clues to disease pathophysiology, but large-scale sequencing does not support the idea that lower-frequency variants have a major role in predisposition to type 2 diabetes.
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| 3. |
- Manning, Alisa, et al.
(author)
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A Low-Frequency Inactivating AKT2 Variant Enriched in the Finnish Population Is Associated With Fasting Insulin Levels and Type 2 Diabetes Risk
- 2017
-
In: Diabetes. - : AMER DIABETES ASSOC. - 0012-1797 .- 1939-327X. ; 66:7, s. 2019-2032
-
Journal article (peer-reviewed)abstract
- To identify novel coding association signals and facilitate characterization of mechanisms influencing glycemic traits and type 2 diabetes risk, we analyzed 109,215 variants derived from exome array genotyping together with an additional 390,225 variants from exome sequence in up to 39,339 normoglycemic individuals from five ancestry groups. We identified a novel association between the coding variant (p.Pro50Thr) in AKT2 and fasting plasma insulin (FI), a gene in which rare fully penetrant mutations are causal for monogenic glycemic disorders. The low-frequency allele is associated with a 12% increase in FI levels. This variant is present at 1.1% frequency in Finns but virtually absent in individuals from other ancestries. Carriers of the FI-increasing allele had increased 2-h insulin values, decreased insulin sensitivity, and increased risk of type 2 diabetes (odds ratio 1.05). In cellular studies, the AKT2-Thr50 protein exhibited a partial loss of function. We extend the allelic spectrum for coding variants in AKT2 associated with disorders of glucose homeostasis and demonstrate bidirectional effects of variants within the pleckstrin homology domain of AKT2.
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| 4. |
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| 5. |
- Bauer, Michael, et al.
(author)
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Association between solar insolation and a history of suicide attempts in bipolar I disorder.
- 2019
-
In: Journal of psychiatric research. - : Elsevier BV. - 1879-1379 .- 0022-3956. ; 113, s. 1-9
-
Journal article (peer-reviewed)abstract
- In many international studies, rates of completed suicide and suicide attempts have a seasonal pattern that peaks in spring or summer. This exploratory study investigated the association between solar insolation and a history of suicide attempt in patients with bipolar I disorder. Solar insolation is the amount of electromagnetic energy from the Sun striking a surface area on Earth. Data were collected previously from 5536 patients with bipolar I disorder at 50 collection sites in 32 countries at a wide range of latitudes in both hemispheres. Suicide related data were available for 3365 patients from 310 onset locations in 51 countries. 1047 (31.1%) had a history of suicide attempt. There was a significant inverse association between a history of suicide attempt and the ratio of mean winter solar insolation/mean summer solar insolation. This ratio is smallest near the poles where the winter insolation is very small compared to the summer insolation. This ratio is largest near the equator where there is relatively little variation in the insolation over the year. Other variables in the model that were positively associated with suicide attempt were being female, a history of alcohol or substance abuse, and being in a younger birth cohort. Living in a country with a state-sponsored religion decreased the association. (All estimated coefficients p<0.01). In summary, living in locations with large changes in solar insolation between winter and summer may be associated with increased suicide attempts in patients with bipolar disorder. Further investigation of the impacts of solar insolation on the course of bipolar disorder is needed.
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| 6. |
- Lauria, A., et al.
(author)
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BMI is an important driver of beta-cell loss in type 1 diabetes upon diagnosis in 10 to 18-year-old children
- 2015
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In: European Journal of Endocrinology. - : BioScientifica. - 0804-4643 .- 1479-683X. ; 172:2, s. 107-113
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Journal article (peer-reviewed)abstract
- Objective: Body weight-related insulin resistance probably plays a role in progression to type 1 diabetes, but has an uncertain impact following diagnosis. In this study, we investigated whether BMI measured at diagnosis was an independent predictor of C-peptide decline 1-year post-diagnosis. Design: Multicentre longitudinal study carried out at diagnosis and up to 1-year follow-up. Methods: Data on C-peptide were collected from seven diabetes centres in Europe. Patients were grouped according to age at diagnosis (less than5 years, n = 126; greater than5 years less than10 years, n = 295; greater than10 years less than18 years, n = 421; greater than18 years, n = 410). Linear regression was used to investigate whether BMI was an independent predictor of change in fasting C-peptide over 1 year. Models were additionally adjusted for baseline insulin dose and HbA1c. Results: In individuals diagnosed between 0 and 5 years, 5 and 10 years and those diagnosed greater than18 years, we found no association between BMI and C-peptide decline. In patients aged 10-18 years, higher BMI at baseline was associated with a greater decline in fasting C-peptide over 1 year with a decrease (beta 95% CI; P value) of 0.025 (0.010, 0.041) nM/kg per m(2) higher baseline BMI (P = 0.001). This association remained significant after adjusting for gender and differences in HbA1c and insulin dose (beta = 0.026, 95% CI = 0.0097, 0.042; P = 0.002). Conclusions: These observations indicate that increased body weight and increased insulin demand are associated with more rapid disease progression after diagnosis of type 1 diabetes in an age group 10-18 years. This should be considered in studies of beta-cell function in type 1 diabetes.
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| 7. |
- Petrov, Dmitry, et al.
(author)
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Machine Learning for Large-Scale Quality Control of 3D Shape Models in Neuroimaging
- 2017
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In: Machine learning in medical imaging. MLMI (Workshop). - Cham : Springer International Publishing. ; 10541, s. 371-378
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Journal article (peer-reviewed)abstract
- As very large studies of complex neuroimaging phenotypes become more common, human quality assessment of MRI-derived data remains one of the last major bottlenecks. Few attempts have so far been made to address this issue with machine learning. In this work, we optimize predictive models of quality for meshes representing deep brain structure shapes. We use standard vertex-wise and global shape features computed homologously across 19 cohorts and over 7500 human-rated subjects, training kernelized Support Vector Machine and Gradient Boosted Decision Trees classifiers to detect meshes of failing quality. Our models generalize across datasets and diseases, reducing human workload by 30-70%, or equivalently hundreds of human rater hours for datasets of comparable size, with recall rates approaching inter-rater reliability.
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| 8. |
- Asan, Noor Badariah, 1984-, et al.
(author)
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Effect of Thickness Inhomogeneity in Fat Tissue on In-Body Microwave Propagation
- 2018
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In: Proceedings of the 2018 IEEE/MTT-S International Microwave Biomedical Conference (IMBIOC). - Philadelphia, USA : IEEE. - 9781538659182 ; , s. 136-138
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Conference paper (peer-reviewed)abstract
- In recent studies, it has been found that fat tissue can be used as a microwave communication channel. In this article, the effect of thickness inhomogeneities in fat tissues on the performance of in-body microwave communication at 2.45 GHz is investigated using phantom models. We considered two models namely concave and convex geometrical fat distribution to account for the thickness inhomogeneities. The thickness of the fat tissue is varied from 5 mm to 45 mm and the Gap between the transmitter/receiver and the starting and ending of concavity/convexity is varied from 0 mm to 25 mm for a length of 100 mm to study the behavior in the microwave propagation. The phantoms of different geometries, concave and convex, are used in this work to validate the numerical studies. It was noticed that the convex model exhibited higher signal coupling by an amount of 1 dB (simulation) and 2 dB (measurement) compared to the concave model. From the study, it was observed that the signal transmission improves up to 30 mm thick fat and reaches a plateau when the thickness is increased further.
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| 9. |
- Asan, Noor Badariah, 1984-, et al.
(author)
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Effects of Blood Vessels on Fat Channel Microwave Communication
- 2018
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In: 2018 IEEE Conference on Antenna Measurements & Applications (CAMA). - : IEEE. - 9781538657959
-
Conference paper (peer-reviewed)abstract
- This study aims to investigate the reliability of intra-body microwave propagation through the fat tissue in presence of blood vessels. Here, we consider three types of blood vessels with different sizes. We investigate the impact of the number of blood vessels and their alignment on the transmission of microwave signals through the fat channel. In our study, we employ two probes that act as a transmitter and a receiver. The probes are designed to operate at the Industrial, Scientific, and Medical radio band (2.45 GHz). For a channel length of 100 mm, our results indicate that the presence of the blood vessels may increase the channel path loss by similar to 1.5 dB and similar to 4.5 dB when the vessels are aligned and orthogonally aligned with the fat channel, respectively.
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| 10. |
- Calzone, Rocco, et al.
(author)
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Innovations in Biomedicine : Measuring Physiological Parameters Becomes As Simple As Applying A Plaster on the Body
- 2019
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In: Proceedings Of The 2019 International Conference On Electromagnetics In Advanced Applications (ICEAA). - New York : IEEE. - 9781728105635 ; , s. 1443-1446
-
Conference paper (peer-reviewed)abstract
- Electromagnetic applications play an essential role in medical research. As a response to the consistent increase in the number of people suffering from various diseases, the medical research is always looking for better diagnostic tools, expedited information transfer technologies, accurate prognosis devices, efficient patient management system and other alternative medicine strategies. In this context, the H2020 Project SINTEC proposes a soft intelligent epidermal communication platform where two main innovations are integrated: soft epidermal electronics and the intra-body communication based on fat tissue as a transmission channel. This proposed platform will host miniaturized, conformal and flexible sensing and data transfer technologies to enable real-time monitoring of certain vital parameters at any time (while doing sport, sleeping or watching television without having to go to a health specialized facility and/or using different devices such as a pulse oximetry, heart rate monitor and thermometer). As part of the phantom development, empirical models relating bioimpedance signals to other physiological signals (ECG, Sp02, Blood Pressure, etc.) is being studied and will be used to optimize phantom -based demonstrators as close as possible to human subjects. To this end, proper characterization of bioimpedance signals in different human subjects is crucial to devise such empirical models. This work presents preliminary results in four human volunteers, with different weight, gender and age, using two types of electrodes configurations. These results show that bioimpedance signals correlate well with volunteer's metadata as predicted by previous works. Finally, the communication through the FAT-channel and also comparisons with the traditional Freespace BLE (Bluetooth Low Energy) protocol will be demonstrated.
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| 11. |
- Ebrahimizadeh, Javad, et al.
(author)
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Electromagnetic Time-Reversal Technique for Monitoring Skull Healing Stages
- 2019
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In: 2019 13th European Conference On Antennas And Propagation (EuCAP). - : IEEE. - 9788890701887
-
Conference paper (peer-reviewed)abstract
- This paper provides a novel non-resonant spectroscopy technique for monitoring of the healing process in skull defects created in cranial surgery. Currently, there is not such a method and information on the healing process which is vital to avoid further complications and for a better understanding of the process. During the healing, which can take several months, the thickness and the permittivity of the skull varies. The proposed approach makes use of the approximated Dyadic Green's function integral equation for deriving the variations in permittivity of the skull. The scattered electric field from the defect is collected using Time-Reversal Array (TRA) in order to produce the Multi-StaticData Matrix (MDM). The singular value decomposition on the MDM matrix based on time reversal operator (TRO) decomposition (known under French acronym DORT), provides information of the permittivity of the defect. The problem of the sensing the defect response after the cranial surgery is formulated for multi-layer medium and it will be shown that the dominant singular values are corresponding to the permittivity of the defect. Finally, the veracity of the theory is clarified by conducting a numerical simulation for a planar multi-layer medium consisting of skin, skull brain and a defect embedded in the skull. We show that the dominant singular values corresponding to the defect permittivity vary significantly which conclude that the dominant singular value can be a good criterion for monitoring the skull healing stages.
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| 12. |
- Gutierrez, Mauricio, et al.
(author)
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Forced response analysis of a transonic turbine using a free interface component mode synthesis method
- 2015
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In: 11th European Conference on Turbomachinery Fluid Dynamics and Thermodynamics, ETC 2015. - : European Conference on Turbomachinery (ETC).
-
Conference paper (peer-reviewed)abstract
- Assessing forced response is crucial during the design phase of turbomachines. Since the analyses are computationally expensive and time-consuming when using full models, Reduced Order Models (ROM) are utilized to decrease the number of Degrees Of Freedom (DOF) and consequently analysis time and cost. The ROM used in the current analysis belongs to the component mode synthesis (CMS) method with a free-interface approach known as Craig-Chang. A transonic high pressure turbine is investigated featuring large ranges of disk and blade dominated modes depending in the Nodal Diameter (ND). The free-interface approach will be assessed in the disk and blade dominated regions with a detailed study of the frequencies and mode shapes. In addition, a forced response analysis within the blade dominated region is evaluated in the paper. Moreover, a study of the amount of modes required in the basis for the reduced order transformation matrix is presented.
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| 13. |
- Gutierrez Salas, Mauricio, et al.
(author)
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Forced response analysis of a mistuned compressor blisk comparing three different reduced order model approaches
- 2016
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In: Proceedings of the ASME Turbo Expo. - : ASME Press. - 9780791849835
-
Conference paper (peer-reviewed)abstract
- Accurate structural modeling of blisk mistuning is critical for the analysis of forced response in turbomachinery. Apart from intentional mistuning, mistuning can be due to the manufacturing tolerances, corrosion, foreign object damage and in-service wear in general. It has been shown in past studies that mistuning can increase the risk of blade failure due to energy localization. For weak blade to blade coupling, this localization has been shown to be critical and higher amplitudes of vibration are expected in few blades. This paper presents a comparison of three reduced order models for the structural modeling of blisks. Two of the models assume cyclic symmetry while the third model is free of this assumption. The performance of the reduced order models for cases with small and large amount of mistuning will be examined. The benefits and drawbacks of each reduction method will be discussed.
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| 14. |
- Kohler, Annegret, et al.
(author)
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Convergent losses of decay mechanisms and rapid turnover of symbiosis genes in mycorrhizal mutualists.
- 2015
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In: Nature Genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 47:4, s. 176-410
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Journal article (peer-reviewed)abstract
- To elucidate the genetic bases of mycorrhizal lifestyle evolution, we sequenced new fungal genomes, including 13 ectomycorrhizal (ECM), orchid (ORM) and ericoid (ERM) species, and five saprotrophs, which we analyzed along with other fungal genomes. Ectomycorrhizal fungi have a reduced complement of genes encoding plant cell wall-degrading enzymes (PCWDEs), as compared to their ancestral wood decayers. Nevertheless, they have retained a unique array of PCWDEs, thus suggesting that they possess diverse abilities to decompose lignocellulose. Similar functional categories of nonorthologous genes are induced in symbiosis. Of induced genes, 7-38% are orphan genes, including genes that encode secreted effector-like proteins. Convergent evolution of the mycorrhizal habit in fungi occurred via the repeated evolution of a 'symbiosis toolkit', with reduced numbers of PCWDEs and lineage-specific suites of mycorrhiza-induced genes.
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| 15. |
- Mathur, Parul, et al.
(author)
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An Efficient Method for Computing the Interaction of Open Ended Circular Waveguide with a Layered Media
- 2018
-
In: Progress In Electromagnetics Research Letters. - : E M W PUBLISHING. - 1937-6480. ; 76, s. 55-61
-
Journal article (peer-reviewed)abstract
- This article presents a new method for studying the near-field electromagnetic interaction between a dielectric filled open ended circular waveguide (OECW) and a layered dielectric structure. The proposed model is based on plane wave spectrum theory using a novel and computationally efficient two step integration method. The first integral, involving multiple singularities in the integration path, is efficiently solved using a deformed elliptical integration path which encircles the singularities of the integral. The infinite domain tail integral involving the slowly converging integrand is further solved using an efficient trigonometric transformation. The proposed OECW based method is capable of determining the unknown material properties of any layered dielectric medium, and hence finds application in nondestructive evaluation of materials.
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| 16. |
- Mathur, Parul, et al.
(author)
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NDECOAX : A software package for nondestructive evaluation of stratified dielectric media
- 2019
-
In: SoftwareX. - : Elsevier. - 2352-7110. ; 9, s. 187-192
-
Journal article (peer-reviewed)abstract
- This article presents a software package based on the C++ language for accurate computation of material properties of a stratified media using an open ended coaxial probe (OECP). Since OECP is one of the most commonly used sensors for evaluation of materials today, the program developed can be customized for real time nondestructive evaluation of materials. The main contribution of this article is a computationally efficient software for solving an infinite domain integral with multiple singularities based on plane wave spectrum theory. The computed results for aperture admittance of the coaxial probe using the developed software show good agreement with both measurements and results from a commercial solver using the finite element method (FEM). It is also proved that, the execution time per frequency point of the developed code is much faster than FEM. (C) 2019 The Authors. Published by Elsevier B.V.
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| 17. |
- Perez, Mauricio D., et al.
(author)
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Microwave Sensors for New Approach in Monitoring Hip Fracture Healing
- 2017
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In: 2017 11th European Conference On Antennas And Propagation (EUCAP). - : IEEE. - 9788890701870 ; , s. 1838-1842
-
Conference paper (peer-reviewed)abstract
- Cyber-Physical System (CPS) applications in lower-extremity bony-fracture rehabilitation systems require real-time biophysical data. Emerging and interesting solutions are microwave approaches that provide good contrast between hard and soft tissues and between local anomalies inside tissues. Preliminarily some contacting non-invasive planar methods have been investigated in their feasibility of detecting human tissues variations with promising results. In this work we introduce two new microwave planar sensors for a new approach of hip fracture healing follow-up tool. They are designed for improved resolution and penetration at frequencies between 1 to 3 GHz in detecting variations in bone, muscle or fat tissues that are expected during a rehabilitation process. The resonant devices are optimized using Frequency Domain Reflectometry and CST (R) environment and validated using clinical trials with volunteers. The new approach is validated using clinical trials with volunteers and patients. These outcomes further emphasize the feasibility of devising systems for fracture rehabilitation.
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| 18. |
- Perez, Mauricio D., et al.
(author)
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New Approach for Clinical Data Analysis of Microwave Sensor Based Bone Healing Monitoring System in Craniosynostosis Treated Pediatric Patients
- 2018
-
In: 2018 IEEE Conference On Antenna Measurements & Applications (CAMA). - : IEEE. - 9781538657959
-
Conference paper (peer-reviewed)abstract
- In the BDAS project one of the goals is to provide a solution to the monitoring bone healing issue complementing current techniques. Data have been collected in clinical trials from infants treated for Craniosynostosis by a craniotomy surgery. The data are collected with a biomedical sensor based in microwave technology. This sensor could be able to sense changes in the composition of the different tissues in the upper-hemisphere of the head by noticing a difference in the propagation of the microwaves, as the bone injury from the craniotomy heals over time. In this thesis, we analyse the clinical data in BDAS project incorporating new approaches with respect to previous analysis methods. These new approaches could give new insight into the proposed solution, but more analysis need to be done.
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| 19. |
- Pickwell, K., et al.
(author)
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Minor amputation does not negatively affect health-related quality of life as compared with conservative treatment in patients with a diabetic foot ulcer : An observational study
- 2017
-
In: Diabetes/Metabolism Research and Reviews. - : Wiley. - 1520-7552. ; 33:3
-
Journal article (peer-reviewed)abstract
- Background: Health-related quality of life (HRQoL) is poor in patients with persistent diabetic foot ulcers and poor HRQoL predicts worse outcomes in these patients. Amputation is often considered a treatment failure, which is why conservative treatment is generally preferred over amputation. However, it is unclear whether minor amputation negatively affects HRQoL compared with conservative treatment in patients with diabetic foot ulcers. Methods: In the cohort of the multicenter, prospective, observational Eurodiale study, we determined difference in change of HRQoL measured by EQ-5D between patients with a diabetic foot ulcers that healed after conservative treatment (n = 676) and after minor amputation (n = 145). Propensity score was used to adjust for known confounders, attempting to overcome lack of randomization. Results: Baseline HRQoL was not significantly different between patients treated conservatively and undergoing minor amputation. In addition, there was no difference in the change of HRQoL between these groups. In patients who healed 6 to 12 months after the first visit, HRQoL on the anxiety/depression subscale even appeared to improve more in those who underwent minor amputation. Conclusions: Minor amputation was not associated with a negative impact on HRQoL in patients with a diabetic foot ulcers. It may therefore not be considered treatment failure in terms of HRQoL but rather a viable treatment option. A randomized controlled trial is warranted to further examine the influence of minor amputations on health-related quality of life.
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| 20. |
- Piovesan, Damiano, et al.
(author)
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DisProt 7.0 : a major update of the database of disordered proteins
- 2017
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In: Nucleic Acids Research. - : Oxford University Press (OUP). - 0305-1048 .- 1362-4962. ; 45:D1, s. d219-D227
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Journal article (peer-reviewed)abstract
- The Database of Protein Disorder (DisProt, URL: www.disprot.org) has been significantly updated and upgraded since its last major renewal in 2007. The current release holds information on more than 800 entries of IDPs/IDRs, i.e. intrinsically disordered proteins or regions that exist and function without a well-defined three-dimensional structure. We have re-curated previous entries to purge DisProt from conflicting cases, and also upgraded the functional classification scheme to reflect continuous advance in the field in the past 10 years or so. We define IDPs as proteins that are disordered along their entire sequence, i.e. entirely lack structural elements, and IDRs as regions that are at least five consecutive residues without well-defined structure. We base our assessment of disorder strictly on experimental evidence, such as X-ray crystallography and nuclear magnetic resonance ( primary techniques) and a broad range of other experimental approaches (secondary techniques). Confident and ambiguous annotations are highlighted separately. DisProt 7.0 presents classified knowledge regarding the experimental characterization and functional annotations of IDPs/IDRs, and is intended to provide an invaluable resource for the research community for a better understanding structural disorder and for developing better computational tools for studying disordered proteins.
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| 21. |
- Redzwan Mohd Shah, Syaiful, et al.
(author)
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Improved Sensor for Non-invasive Assessment of Burn Injury Depth Using Microwave Reflectometry
- 2019
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In: 2019 13th European Conference on Antennas and Propagation (EuCAP). - 9788890701887
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Conference paper (peer-reviewed)abstract
- The European project “Senseburn” aims to develop a non-invasive diagnostic instrument for assessing the depth and propagation of human burns in the clinical scenario. This article introduces an improved flexible microwave split-ring resonator-based sensor, as a new development in this project. The excitation system and the fabrication process are the major improvements with respect to its precedent microwave sensor, both based in polydimethylsiloxane (PDMS) and copper. Both improvements are introduced together with the design of the sensor and of the experimental setup. Human tissue emulating phantoms are designed, fabricated, validated, and employed to emulate different burn depths and to validate the conceptual functionality of the proposed sensor. The Keysight dielectric probe 85070E is employed for the phantom validation. The analysis suggests that the sensor could estimate the burn depth. Future works will be carried out with ex vivo human tissues.
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| 22. |
- Redzwan, Syaiful, et al.
(author)
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Analysis of Thickness Variation in Biological Tissues using Microwave Sensors for Health Monitoring Applications
- 2019
-
In: IEEE Access. - 2169-3536. ; 7, s. 156033-156043
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Journal article (peer-reviewed)abstract
- Microwave sensing technique is a possible and attractive alternative modality to standard Xrays,magnetic resonance imaging, and computed tomography methods for medical diagnostic applications.This technique is beneficial since it uses non-ionizing radiation and that can be potentially used for themicrowave healthcare system. The main purpose of this paper is to present a microwave sensing techniqueto analyze the variations in biological tissue thickness, considering the effect of physiological and biologicalproperties on microwave signals. With this goal, we have developed a two-port non-invasive sensor systemcomposed of two split ring resonators (SRRs) operating at an Industrial, Scientific, and Medical frequencyband of 2.45 GHz. The system is verified using the amplitude and phase of the transmitted signal in ex-vivomodels, representing different tissue thicknesses. Clinical applications such as the diagnosis of muscularatrophy can be benefitted from this study.
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| 23. |
- Redzwan, Syaiful, et al.
(author)
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Initial in-vitro trial for intra-cranial pressure monitoring using subdermal proximity-coupled split-ring resonator
- 2018
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In: IMBioc 2018 - 2018 IEEE/MTT-S International Microwave Biomedical Conference. - : Institute of Electrical and Electronics Engineers (IEEE). - 9781538659182 ; , s. 73-75
-
Conference paper (peer-reviewed)abstract
- Intra cranial pressure (ICP) monitoring is used in treating severe traumatic brain injury (TBI) patients. All current clinical available measurement methods are invasive presenting considerable social costs. This paper presents a preliminary investigation of the feasibility of ICP monitoring using an innovative microwave-based non-invasive approach. A phantom mimicking the dielectric characteristics of human tissues of the upper part of the head at low microwave frequencies is employed together to a proof-of-concept prototype based on the proposed approach consisting in a readout system and a sub-dermally implanted passive device, both based in split ring resonator techniques. This study shows the potential of our approach to detect two opposite pressure variation stages inside the skull. The employed phantom model needs to be improved to support finer variations in the pressure and better phantom parts, principally for the skull mimic and the loss tangent of all mimics.
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| 24. |
- Redzwan, Syaiful, et al.
(author)
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Split-Ring Resonator Sensor Penetration Depth Assessment Using In Vivo Microwave Reflectivity and Ultrasound Measurements for Lower Extremity Trauma Rehabilitation
- 2018
-
In: Sensors. - : MDPI. - 1424-8220. ; 18:2
-
Journal article (peer-reviewed)abstract
- In recent research, microwave sensors have been used to follow up the recovery of lower extremity trauma patients. This is done mainly by monitoring the changes of dielectric properties of lower limb tissues such as skin, fat, muscle, and bone. As part of the characterization of the microwave sensor, it is crucial to assess the signal penetration in in vivo tissues. This work presents a new approach for investigating the penetration depth of planar microwave sensors based on the Split-Ring Resonator in the in vivo context of the femoral area. This approach is based on the optimization of a 3D simulation model using the platform of CST Microwave Studio and consisting of a sensor of the considered type and a multilayered material representing the femoral area. The geometry of the layered material is built based on information from ultrasound images and includes mainly the thicknesses of skin, fat, and muscle tissues. The optimization target is the measured S-11 parameters at the sensor connector and the fitting parameters are the permittivity of each layer of the material. Four positions in the femoral area (two at distal and two at thigh) in four volunteers are considered for the in vivo study. The penetration depths are finally calculated with the help of the electric field distribution in simulations of the optimized model for each one of the 16 considered positions. The numerical results show that positions at the thigh contribute the highest penetration values of up to 17.5 mm. This finding has a high significance in planning in vitro penetration depth measurements and other tests that are going to be performed in the future.
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| 25. |
- Velander, Jacob, et al.
(author)
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A Four-Layer Phantom for Testing In-Vitro Microwave-Based Sensing Approach in Intra-Cranial Pressure Monitoring
- 2018
-
In: Proceedings Of The 2018 IEEE/MTT-S International Microwave Biomedical Conference (IMBioC). - : IEEE. - 9781538659182 ; , s. 49-51
-
Conference paper (peer-reviewed)abstract
- Multi-layer phantoms in proofs of concept, designs and validations of both microwave-based biomedical sensing and imaging system are becoming popular means to facilitate in-vitro experiments. In addition, they can contribute significantly to reduce animal use in scientific experimentation. In this paper, we design and fabricate a four-layer phantom composed of skin, skull, cerebrospinal fluid and brain mimic tissues to work between 2 and 3 GHz. In addition, the phantom incorporates a mechanism to produce pressure variation between the cerebrospinal fluid and the brain mimic tissues. This phantom is used in an in-vitro experiment to test and validate a new approach which could sense intra-cranial pressure variations through a microwave-based reflection method. The similarity of the phantom's tissues with human tissues from the viewpoint of the microwave response is analyzed in comparison with data from Italian Institute of Applied Physics in Florence. We found good agreement for the dielectric constant (Rel. Err. < 13 % for 68% of significance) in skin, cerebrospinal fluid and brain mimic tissues. For the skin, we got also good agreement for the loss tangent (Rel. Err. < 11 % for 68% of significance). The skull mimic phantom was stiff enough, but even presenting considerable errors, it was still good enough for the experiment. In addition, the capability of the phantom to operate at different pressures is discussed.
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