Iteracinis optimizavimu pagrįsto akies dugno kraujagyslių trasavimo metodo variantas

Akies dugne matomos smulkios žmogaus kraujagyslės. Iš jų pakitimų galima diagnozuoti įvairias sisteminių ligų komplikacijas. Dėl to daug dėmesio skiriama automatiniams kraujagyslių stebėjimo akies dugno vaizduose algoritmams. Daugelis esamų kraujagyslių trasavimo metodų pradeda trasavimą arba nuo daugelio automatiškai rastų taškų, arba nuo vartotojo interaktyviai pažymėtų taškų. Šiame darbe buvo siekiama plačiau išnagrinėti galimybę pradėti trasavimą nuo vieno automatiškai gautotaško, kurio priklausymo kraujagyslei tikimybė labai didelė. Naudojant straipsnyje aprašytą algoritmą trasavimas pradedamas randant pradinį tašką pagal skirtumo tarp skaitmeninio vaizdo raudono ir žalio RGB komponentų reikšmes. Kraujagyslės trasuojamos keliomis kryptimis nuo pradinio taško. Tolesni kraujagyslės taškai randami ieškant didžiausios tikslo funkcijos reikšmės. Tyrimas leido įsitikinti, kad pradedant kraujagyslių trasavimą nuo vieno taško, galima pasiekti kokybę, palyginamą su kitų kraujagyslių radimo metodų kokybe.Iterative Variant of the Optimisation-Based Eye Fundus Blood Vessel Tracking MethodMartynas Patašius, Vaidotas Marozas, Darius Jegelevičius, Arūnas Lukoševičius SummaryEye fundus is the place where human microvasculature can be observed directly. The vascular changes that can be detected there make it possible to diagnose complications of various systemic diseases. Thus a lot of attention is paid to blood vessel detection in eye fundus images. Most of the currently used blood vessels tracking methods start the tracking either from a set of automatically generated seed points, or from the manually marked seed points. In this study, we tried to explore the possibility to start the tracing from one point that belongs to the blood vessel with a high probability. Using the method described here blood vessel tracking starts from fi nding a seed point according to the difference of red and green RGB components. The next points of the blood vessel are found by searching for the maximal values of the goal function. The study has corroborated that it is possible to achieve a blood vessel detection quality comparable to the quality achieved by other blood vessel detection methods by starting blood vessel tracking from a single point according to the described method

A Noise-Adaptive Method for Detection of Brief Episodes of Paroxysmal Atrial Fibrillation

Abstract The aim of this work is to develop a method for detection of brief episode paroxysmal atrial fibrillation (PAF Introduction The detection of brief episode paroxysmal atrial fibrillation (PAF) is an important problem to solve since atrial fibrillation (AF) is a progressive disorder. If not treated, PAF usually becomes more frequent and longer until it becomes permanent Automatic AF detection can be done in different waysone is based on identification of P-wave absence and another on the analysis of RR interval irregularity. Since P-waves are not apparent during AF such knowledge can be combined with RR irregularity information in order to improve the performance of AF detection Recently, there has been a growing interest in developing algorithms for detection of brief AF episodes. A sample entropy based method was proposed that is capable of detecting AF using only 12 consecutive RR intervals A novel detector architecture was recently proposed, where information on P wave presence/absence, heart rate irregularity, and atrial activity analysis was combined, using an artificial neural network as classifier In this study, the proposed method is based on atrial activity extraction using an echo state network (ESN) recently introduced as a unified solution to the problem of QRST cancellation in the presence of substantial variation in beat morphology and/or occasional ectopic beats Methods The main processing steps of the proposed AF detector are illustrated i

Visual Analytics for Health Monitoring and Risk Management in CARRE

With the rise of wearable sensor technologies, an increasing number of wearable health and medical sensors are available on the market, which enables not only people but also doctors to utilise them to monitor people’s health in such a consistent way that the sensors may become people’s lifetime companion. The consistent measurements from a variety of wearable sensors implies that a huge amount of data needs to be processed, which cannot be achieved by traditional processing methods. Visual analytics is designed to promote knowledge discovery and utilisation of big data via mature visual paradigms with well-designed user interactions and has become indispensable in big data analysis. In this paper we introduce the role of visual analytics for health monitoring and risk management in the European Commission funded project CARRE which aims to provide innovative means for the management of cardiorenal diseases with the assistance of wearable sensors. The visual analytics components of timeline and parallel coordinates for health monitoring and of node-link diagrams, chord diagrams and sankey diagrams for risk analysis are presented to achieve ubiquitous and lifelong health and risk monitoring to promote people’s health

MyHealthAvatar and CARRE: case studies of interactive visualisation for Internet-enabled sensor-assisted health monitoring and risk analysis

With the progress of wearable sensor technologies, more wearable health sensors have been made available on the market, which enables not only people to monitor their health and lifestyle in a continuous way but also doctors to utilise them to make better diagnoses. Continuous measurement from a variety of wearable sensors implies that a huge amount of data needs to be collected, stored, processed and presented, which cannot be achieved by traditional data processing methods. Visualisation is designed to promote knowledge discovery and utilisation via mature visual paradigms with well-designed user interactions and has become indispensable in data analysis. In this paper we introduce the role of visualisation in wearable sensor-assisted health analysis platforms by case studies of two projects funded by the European Commission: MyHealthAvatar and CARRE. The former focuses on health sensor data collection and lifestyle tracking while the latter aims to provide innovative means for the management of cardiorenal diseases with the assistance of wearable sensors. The roles of visualisation components including timeline, parallel coordinates, map, node-link diagrams, Sankey diagrams, etc. are introduced and discussed

The influence of temperature for crack opening in reinforced concrete shell of pressure piping in Kruonis pump storage power plant

Veikiant suminiam agresyvių aplinkų ir apkrovų poveikiui gelžbetoninėse konstrukcijose gali susiformuoti plyšiai. Pagal plyšių pavojingumą konstrukcijai išskiriamos trys plyšių grupės:1) nepavojingi plyšiai, 2) pavojingi plyšiai, 3) tarpinio pavojingumo plyšiai. Darbe analizuoti dėl temperatūros kaitos atsivėrę plyšiai Kruonio hidroakumuliacinės elektrinės slėginio vamzdyno gelžbetoniniame apvalkale. Įvertinus vamzdynų techninę būklę, detaliau analizuoti plyšiai ir deformacijos dėl temperatūros perkričių. Pateikiamos būdingos iliustracijos, skaičiavimai bei rekomendaciniai pasiūlymai šių pažaidų remontui.Cracks in the reinforced concrete appear because of both the aggressive enviroment and the load influence. Cracks are classified according to their geometry (length, width, depth) and statistical parameters (mean and variance of the number of cracks per unit area), according cracks riskiness for structures and so on. There are known three types of cracks according their riskiness: 1) secure cracks, 2) dangerous cracks, 3) medium risk cracks. In this paper, cracks opening in reinforced concrete shell of pressure piping at Kruonis pumped storage power station due to temperature change are analyzed. Detailed analysis of cracks and deformations due to temperature changes were performed after the evaluation of technical state of the pipeline. Specific illustrations, calculations and guidance for repair of these deteriorations were offered.Žemės ūkio akademijaVytauto Didžiojo universiteta

Three-Dimensional Freehand Ultrasound Strain Elastography Based on the Assessment of Endogenous Motion: Phantom Study

The purpose of this paper is to present the results of the pilot experiments demonstrating proof of concept of three-dimensional strain elastography, based on freehand ultrasound for the assessment of strain induced by endogenous motion. The technique was tested by inducing pulsatility in an agar-based tissue mimicking phantom with inclusions having different stiffness and scanning the 1D array with an electromagnetic position sensor. The proof of concept is explored with a defined physical phantom and the adopted algorithm for strain analysis. The agar-based phantom was manufactured with two cylindrical inclusions having different stiffness (7 kPa and 75 kPa in comparison to the background 25 kPa) and scattering properties. The internal strain in the phantom was introduced by mimicking a pulsating artery. The agar mixture displacements were estimated by using the GLUE algorithm. The 3D isosurfaces of inclusion from rendered volumes obtained from the B-mode image set and strain elastograms were reconstructed and superimposed for a quantitative comparison. The correspondence between the B-mode image-based inclusion volume and the strain elastography-based volume was good (the Jaccard similarity coefficient in the range 0.64–0.74). The obtained results confirm the 3D freehand endogenous motion-based elastography as a feasible technique. The visualization of the inclusions was successful. However, quantitative measurements showed that the accuracy of the method in volumetric measurements is limited

Corneal thickness factor and artificial intelligent control for intraocular pressure estimation

Estimation and valuation of confounding factors via artificial intelligent technologies is of the main importance when eliminating intraocular pressure tonometric mistakes. Current investigation focuses on intraocular pressure (IOP) magnitude, being the basis in diagnosis and monitoring of ocular hypertension, valuation reliability. The statistical modeling of experimental data, proved the central corneal thickness (CCT) to be confounding factor and positively correlated source of variation in intraocular pressure measurements among ocular hypertension subjects. To fix reliability of measured intraocular pressure magnitudes the artificial intelligent control in terms of numerical simulations via finite element method is proposed. Referring to statistical modeling of experimental data and provided numerical simulations in general conclusion we point the imperative of the artificial intelligent control method applied for introduce of CCT correction factor when having measured IOP via GAT. The convergence of proposed artificial intelligent control method proves it to be an appropriate alternative for ocular hypertension misdiagnose

Main Uncertainties in the RF Ultrasound Scanning Simulation of the Standard Ultrasound Phantoms

Ultrasound echoscopy technologies are continuously evolving towards new modalities including quantitative parameter imaging, elastography, 3D scanning, and others. The development and analysis of new methods and algorithms require an adequate digital simulation of radiofrequency (RF) signal transformations. The purpose of this paper is the quantitative evaluation of RF signal simulation uncertainties in resolution and contrast reproduction with the model of a phased array transducer. The method is based on three types of standard physical phantoms. Digital 3D models of those phantoms are composed of point scatterers representing the weak backscattering of the background material and stronger backscattering from inclusions. The simulation results of echoscopy with sector scanning transducer by Field II software are compared with the RF output of the Ultrasonix scanner after scanning standard phantoms with 2.5 MHz phased array. The quantitative comparison of axial, lateral, and elevation resolutions have shown uncertainties from 9 to 22% correspondingly. The echoscopy simulation with two densities of scatterers is compared with contrast phantom imaging on the backscattered RF signals and B-scan reconstructed image, showing that the main sources of uncertainties limiting the echoscopy RF signal simulation adequacy are an insufficient knowledge of the scanner and phantom’s parameters. The attempt made for the quantitative evaluation of simulation uncertainties shows both problems and the potential of echoscopy simulation in imaging technology developments. The analysis presented could be interesting for researchers developing quantitative ultrasound imaging and elastography technologies looking for simulated raw RF signals comparable to those obtained from real ultrasonic scanning

Simulation of Ultrasound RF Signals Backscattered from a 3D Model of Pulsating Artery Surrounded by Tissue

Arterial stiffness is an independent predictor of cardiovascular events. The motion of arterial tissues during the cardiac cycle is important as a mechanical deformation representing vessel elasticity and is related to arterial stiffness. In addition, arterial pulsation is the main source of endogenous tissue micro-motions currently being studied for tissue elastography. Methods based on artery motion detection are not applied in clinical practice these days, because they must be carefully investigated in silico and in vitro before wide usage in vivo. The purpose of this paper is to propose a dynamic 3D artery model capable of reproducing the biomechanical behavior of human blood vessels surrounded by elastic tissue for endogenous deformation elastography developments and feasibility studies. The framework is based on a 3D model of a pulsating artery surrounded by tissue and simulation of linear scanning by Field II software to generate realistic dynamic RF signals and B-mode ultrasound image sequential data. The model is defined by a spatial distribution of motions, having patient-specific slopes of radial and longitudinal motion components of the artery wall and surrounding tissues. It allows for simulating the quantified mechanical micro-motions in the volume of the model. Acceptable simulation errors calculated between modeled motion patterns and those estimated from simulated RF signals and B-scan images show that this approach is suitable for the development and validation of elastography algorithms based on motion detection

The influence of temperature change for crack opening in reinforced concrete shell of pressure piping in Kruonis pump storage power plant

Plyšiai klasifikuojami pagal jų geometrinius (ilgį, plotį, gylį) ir statistinius parametrus (vidutinis plyšių skaičius ir dispersija ploto vienete), pagal pavojingumą konstrukcijai ir kt. Šiame darbe analizuoti dėl temperatūros kaitos atsivėrę plyšiai Kruonio hidroakumuliacinės elektrinės slėginio vamzdyno gelžbetoniniame apvalkale. Įvertinus vamzdynų techninę būklę, detaliau analizuoti plyšiai ir deformacijos dėl temperatūros perkričių. Pateikiamos būdingos iliustracijos, skaičiavimai bei rekomendaciniai pasiūlymai šių pažaidų remontuiCracks are classified according to their geometry (length, width, depth) and statistical parameters (mean and variance of the number of cracks per unit area), according cracks riskiness for structures and so on. In this paper, cracks opening in reinforced concrete shell of pressure piping at Kruonis pumped storage power station due to temperature change are analyzed. Detailed analysis of cracks and deformations due to temperature changes were performed after the evaluation of technical state of the pipeline. Specific illustrations, calculations and guidance for repair of these deteriorations were offeredVytauto Didžiojo universitetasŽemės ūkio akademij