Jan Mikulka

Soft-tissues image processing: comparison of traditional segmentation methods with 2D active contour methods

Soft-tissues Image Processing: Comparison of Traditional Segmentation Methods with 2D active Contour Methods The paper deals with modern methods of image processing, especially image segmentation, classification and evaluation of parameters. It focuses primarily on processing medical images of soft tissues obtained by magnetic resonance tomography (MR). It is easy to describe edges of the sought objects using segmented images. The edges found can be useful for further processing of monitored object such as calculating the perimeter, surface and volume evaluation or even three-dimensional shape reconstruction. The proposed solutions can be used for the classification of healthy/unhealthy tissues in MR or other imaging. Application examples of the proposed segmentation methods are shown. Research in the area of image segmentation focuses on methods based on solving partial differential equations. This is a modern method for image processing, often called the active contour method. It is of great advantage in the segmentation of real images degraded by noise with fuzzy edges and transitions between objects. In the paper, results of the segmentation of medical images by the active contour method are compared with results of the segmentation by other existing methods. Experimental applications which demonstrate the very good properties of the active contour method are given.

In vitro motor patterns and electrophysiological changes in patients with colonic diverticular disease

PurposeThe underlying mechanism responsible for motility changes in colonic diverticular disease (DD) is still unknown. In the present study, our aim was to investigate the structural and in vitro motor changes in the sigmoid colon of patients with DD.MethodsMuscle bath, microelectrodes and immunohistochemical techniques were performed with samples obtained from the left and sigmoid colon of patients with DD and compared with those of patients without DD.ResultsThe amplitude and area under the curve of the spontaneous rhythmic phasic contractions were greatly reduced in patients with DD whereas their frequency and tone remained unaltered. Electrical field stimulation induced a neurally mediated, enhanced ON-contraction (amplitude) in patients with DD and increased the duration of latency of OFF-contractions. The resting membrane potential of smooth muscle cells was hyperpolarized and the amplitude of the inhibitory junction potential was increased in patients with DD. In contrast, no significant histological differences were observed in patients with DD as smooth muscle (circular and longitudinal layers), interstitial cells of Cajal, glial cells and myenteric neurons densities remained unaltered.ConclusionsSigmoid strips from patients with asymptomatic DD showed an altered motor pattern with reduced spontaneous motility and enhanced neurally mediated colonic responses involving both excitatory and inhibitory motor pathways. No major neural and muscular structural elements were detected at this stage of the disease. These findings could be valuable in understanding the pathophysiology of this prevalent digestive disease.

CCK and Barker Coding Implementation in IEEE 802.11b Standard

This paper deals with a Matlab-simulink simulation of IEEE 802.11b physical Layer specification. There was made a Matlab Simulink program that simulates 4 data rates (1, 2, 5.5, 11 Mbps) specified in the 802.1 lb standard. Program includes Barker coding implementation for lower data rates (1,2 Mbps) and CCK (complementary code keying) for higher data rates providing 5.5 and 11 Mbps. All data rates are using DSSS (direct sequence spread spectrum). Basic description of the program and results in graphical and numerical form are introduced as a BER to Eb/NO dependence.

ImageJ plug-ins for microscopic image processing

The article deals with initial research into the methods of microscopic image processing methods for the study of diverticular disease. Functional and structural changes were found in tissues of persons afflicted with diverticular disease in previous medical research. The acquired images were processed manually. The goal of research into image processing methods for automatic or semiautomatic processing followed by manual supervision is to simplify and speed-up the image processing and evaluation of object parameters. The research is focused on increasing the accuracy of and speeding up the evaluation of tissue properties. ImageJ plug-ins implementing the proposed algorithms were developed for five kinds of image processing: circular muscle layer, longitudinal muscle layer, myenteric plexus layer, interstitial cells in myenteric plexus layer and interstitial cells of cajal in smooth muscle layer.

Gender recognition using PCA and DCT of face images

In this paper we propose a gender recognition algorithm of face images. We have used PCA and DCT for dimensionality reduction. The algorithm is based on a genetic algorithm to improve the selection of training set of images for the PCA algorithm. Genetic algorithm helps to select the images, which best represent each gender, from the image database. We have evaluated a nearest neighbor classifier as well as a neural network. Experimental results show a correct identification rate of 85,9%.

Segmentation of brain tumor parts in magnetic resonance images

The problem most frequently encountered in the practical processing of medical images consists in the lack of instruments enabling machine evaluation of the images. A typical example of this situation is perfusion analysis of brain tumor types. The first and very significant step lies in the segmentation of individual parts of the brain tumor; after segmentation, the rate of penetration by the applied contrast agent is observed in the parts. The common method, in which a high error rate has to be considered, is to mark these tumor portions manually. Within the second step of the segmentation procedure, the monitoring of perfusion in the segmented tissues is realized together with the correlation to model cases. The quality of brain tissue segmentation exerts significant influence on the quality of evaluation of perfusion parameters; consequently, the tumor type recognition is also influenced. This means that the design of a suitable, accurate, and reproducible method constitutes a critical point within perfusion analysis. In this context, reproducibility is an important aspect owing to the preservation of segmentation conditions in monitoring the development of a tumor in time. The authors describe classification methods enabling the segmentation of images acquired via magnetic resonance tomography.

Classification of jawbone cysts via orthopantomogram processing

The subject of the paper is a method proposed for automated evaluation of the parameters of orthopantomograms of cystic disorders in human jawbones. The main problem in medical diagnostic is the low repeatability due to the subjective evaluation of images/pictures without using a tool for image processing. An available database of images of cysts is described in the paper. Results of a fast automated segmentation by the live-wire method are also given. Selected segments were processed in the ImageJ Java environment. In the cystic regions their basic statistical and shape properties were evaluated. Results of the evaluation are given in the paper conclusion. In the next stage of the research, the values obtained will be compared with the subjective evaluation by radiologists and the possibility will be discussed of exploiting selected parameters or their combinations for an automatic assessment of the level of cystic disorders.

Processing of MR Slices of Temporomandibular Disc for 3D Visualization

This article deals with a segmentation of MR images in temporomandibular joint (TMJ) area. The TMJ belongs to small but the most overloaded joint of the human body. It consists of the head of the mandible and articular fossa (1). Between them is the mandibular disc. The mandibular disc is a cartilage for a force transmission. The physiological placement of the disc is on the top of the mandibular head. One of the frequent diseases is the disc dislocation from the physiological placement therefore there is a blocking of the mandibular head movement. In the worse case it can come to the total disc deformation (2). The aim of this work is to obtain the most exact image or model of the mandibular disc for the right assessment of a treatment in order to minimize the invasive surgery. There was chosen an active contour method based on level set partial difierential equation for the MR image segmentation (3,4). There was found the boundary of the mandibular disc in the noised image of low contrast with suitable parameters and initial curve without of any kind of preprocessing. The article shows our results of the segmentation of some MR slices with visible mandibular disc. These results are poised to following postprocessing which will be the 3D model of the mandibular disc creation. There are described some methods for this kind of preprocessing.

Complementary Code Keying Implementation in the Wireless Networking

This paper deals with a Matlab-simulink simulation of IEEE 802.11 b Physical Layer specification. There was made a Matlab Simulink program that simulates 4 data rates (1, 2, 5.5, 11 Mbps) specified in the 802.11 b standard. Program includes Barker coding implementation for lower data rates (1,2 Mbps) and CCK (complementary code keying) for higher data rates providing 55 and 11 Mbps. All data rates are using DSSS (direct sequence spread spectrum). Basic description of the program and results in graphical and numerical form are introduced as a BER to Eb/N0 dependence.

Data processing in studying the temporomandibular joint, using MR imaging and sonographic techniques

The temporomandibular joint is one of the most complicated joints in the human body. Diagnosing its disorders is difficult because the pain is mistakenly taken for toothache, pain in the jaw bones, etc. The paper deals with a post-processing tomographic examination of temporomandibular joint. An interesting post-processing method was used to increase the contrast related to relaxation time T2. Both increasing the contrast and enhancing the arthritic region were realized by processing two MR images in different echo-times. The enhancement rate is realized on the basis of subjective MR image evaluation by the surgeon. Magnetic resonance images (MRIs) are of very low resolution and contrast. An appropriate algorithm has been found, which consists of pre-processing the image by a smoothing filter, focusing, and four-phase level set segmentation. This method segments the image on the basis of the intensity of respective regions and is thus suitable to be applied to the above MR images, in which no sharp edges occur.