Lačezar Ličev

Inter-Rater Reliability of Carotid Atherosclerotic Plaque Quantification by 3-Dimensional Sonography

Embolization from atherosclerotic carotid plaques is the most common cause of ischemic stroke; therefore, identification of high‐risk plaques by sonography is important. The aim of this study was to investigate the agreement between 2 investigators in the evaluation of sonographic parameters relating to plaque stability.

Adjusting the input ultrasound image data and the atherosclerotic plaque detection in the carotid artery by the FOTOMNG system

Stroke is the third most frequent cause of death. Specifically, ischemic stroke accounts for the largest group of this kind of cases. Despite all the advances in medical therapeutic methods, no methods that would reliably reduce mortality from ischemic stroke have been found. Prevention is still the most significant way to combat stroke. When the frequent cause of ischemic stroke is atherosclerotic plaque in the carotid artery, its exploration can help to determine the development of the disease. These problems were very extensively discussed in October 2013 during the XVI International Neurosonology Congress in Sofia organized under the auspices of World Research Neurosonology Group, Bulgarian Neurosonology and Cerebral Hemodynamics Association. Our goal was to develop special modules for carotid artery picture processing (AVI file processing, reparation and reconstruction) and modules containing tools for automated carotid artery plaque detection; and to solve its measurement and three-dimensional modelling of the carotid artery and the plaque. New modules were implemented into the FOTOMNG system and tested on appropriate input data files, which verified their functionality and applicability.

Equipment for 3-D Picturing and Measurement of Atherosclerotic Plaque

Equipment for 3-D Picturing and Measurement of Atherosclerotic Plaque This contribution presents a management system with the achieved results of a complex grant project focused on the development of equipment for the 3-D picturing of a carotid artery. This problem was solved during years 2006 - 2008 by specialists from the Faculty of Mechanical Engineering VŠB-TUO, Faculty of Electrical Engineering and Computer Science VŠB-TUO and Neurological Clinic FN Ostrava during the solving of research project GA 101/06/0491 supported by the Czech Science Foundation. The main goal is mechanical system for the exact measurement of Atherosclerotic Plaque (AC plaque) in a carotid artery, including the control system and synchronizations with the heart activity. The obtained pictures enable the necessary analysis and acquisition of data for Atherosclerotic Plaque with appropriate accuracy and recurring measurements. These results open the way for medical use.

Analysis and diagnostics of the brain-stem ultrasound images

The medical sonography is an ultrasound-based technique used to visualize internal organs. It is based on detecting the reflections of the waves emitted by a probe. The waves may have various frequencies. Generally, the higher the frequency is, the better and more detailed output images we can get. However, if we want to obtain the brain-stem ultrasound images suitable for the Parkinson disease diagnostics, we can only use the low-frequency probes due to the presence of skull. For this reason, the output images will necessarily be of low quality. In spite of that, these images are essential for the Parkinson disease diagnostics and treatment because, except outer symptoms, they provide the only way how to determine the existence and seriousness of the disease. The low image quality may even lead to the different or inaccurate diagnosis of same image from different medical doctors. Our objective is to create a tool that should help to minimize the physicians subjectivity in the final diagnosis and should provide more exact information about the processed images.

Evaluation of Sandstone Internal Structure with Application of Micro-CT and FOTOM System

The sandstone internal structure is one of the most important factors controlling mechanical properties of this stone. There are many methods enabling study of the properties and character of the internal structure. The known methods are based on the penetration of a chosen medium of a detected volume into the pores or they are based on image analysis of rock slices, where fluorescent colouring highlights the pores. Unfortunately, these methods have a destructive character and, therefore, it is not possible to use the stone samples again. The possibility to re-use the samples makes the micro-CT a very useful tool. Interpretation of the micro-CT results in combination with the results of other methods may enable more detailed view into the internal structure. We studied widely used Czech sandstones using the micro-CT in the course of our experiment. Next, the acquired data was evaluated in commercial software VGStudio MAX 2.2 and also in our FOTOMNG system. We implemented new specialized module in this system for evaluating of such data. For a measurement we prepared several image preprocessing methods. This preprocessing is consisted for example from image binary thresholding for a better diversity between inner porosity and sandstone itself or colour inversion. As addition we implemented function for cropping the samples, due to depreciation of the sample borders caused by repeated measurement. We are able to calculate the value of porosity, for whole series a volume of porespace of sandstone samples or other statistical values. Results and limitations of interpretability are discussed in this article.

New Approach to Steganography Detection via Steganalysis Framework

The aim is to propose basic steganalytical tool that can use multiple methods of analysis. We describe two detection methods that were implemented. These methods include improved detection capability than conventional steganalytical tools thanks to use of artificial neural network and several other innovative improvements. In our work is important to understand the behavior of the targeted steganography algorithm. Then we can use its weaknesses to increase the detection capability. We analyze prepared stegogrammes by application of several conventional algorithms such as image difference. Then we can determine where are the most suitable areas of image for embedding the message by steganography algorithm.

An Enhanced Method for Automatic Detection and Segmentation of Carotid Artery in Ultrasound Images

This paper deals with processing of ultrasonic images of carotid arteries. These images often suffer from low quality, intensity inhomogeneity and artefacts. Due to this, edges of segmented objects may be corrupted. Conventional methods for image processing are therefore insufficient. The newly developed method suited for automatic circular object detection and segmentation is capable to keep the original arterial borders, while precisely segmenting the eventual pathology. Hough transform was used for artery detection. Active contour based on level set methods was adjusted according to our needs and applied for the object segmentation.

Advances in the development of an imaging device for plaque measurement in the area of the carotid artery

This paper describes the advances in the development and subsequent testing of an imaging device for three-dimensional ultrasound measurement of atherosclerotic plaque in the carotid artery. The embolization from the atherosclerotic carotid plaque is one of the most common causes of ischemic stroke and, therefore, we consider the measurement of the plaque as extremely important. The paper describes the proposed hardware for enhancing the standard ultrasonic probe to provide a possibility of accurate probe positioning and synchronization with the cardiac activity, allowing the precise plaque measurements that were impossible with the standard equipment. The synchronization signal is derived from the output signal of the patient monitor (electrocardiogram (ECG)), processed by a microcontroller-based system, generating the control commands for the linear motion moving the probe. The controlling algorithm synchronizes the movement with the ECG waveform to obtain clear images not disturbed by the heart activity.

Search and Implementation of Optimization Algorithms in Analysis of Ultrasonic Pictures in Neurology

This contribution deals with search and implementation of optimization algorithms in analyzing and evaluating objects of interest present in ultrasound images as well as assessing the progress or regressions illustrated in these objects. These objects are highly significant from a medical perspective and include atherosclerotic plaque in carotid arteries, the intima-media thickness in the distal part of the common carotid artery, cerebral cortex size and brain stem findings in cases of Parkinson disease. Here, we describe procedures employing common principles and methods for recognizing points of interest in images that may serve in finding and determining pixel coordinates and other parameters and properties of analyzed objects. We use the stochastic optimization algorithm to optimize the energy function of deformable models used to approximate the locations and shapes of object boundaries in medical images. We suppose that evolutionary algorithm called SOMA can be used to find the desired global solution. Evolutionary algorithms are based on principles of evolution found in nature and respect the Darwin‘s theory of natural selection according to the defined cost function and gene recombination and mutation. As the computation of gradient vector flow field and also the evolution of active contour are computationally very expensive, we investigate the suitability of the GPU for a parallel implementation.

The photogrammetric system FOTOM and recognition of the objects of interest

The recognition of points of interest leads to the detection and consequent specification of the values of Xi and Yi coordinates. The result is a data file of the coordinates. The problem domain is divided into two parts. The first one includes the processing of graphic information, while the second concentrates on searching for the points and objects of interest.