Browsing by Author "Platkajis, Ardis"

Now showing 1 - 4 of 4
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    Computer Analysis of Knee by Magnetic Resonance Imaging Data
    (2016-12-01) Suponenkovs, Artjoms; Markovics, Zigurds; Platkajis, Ardis; Rīga Stradiņš University
    The examination of knee cartilage degradation by magnetic resonance imaging (MRI) data is essential due to the reduction in physical activity of the population and a rising number of patients with osteoarthritis(OA). The main aim of this publication is to show a new approach for analyzing knee tissue by MRI data. The present paper investigates the problems of relaxation times calculation, medical image segmentation and statistical texture features calculation. Proposed paper describes an approach for medical image segmentation, relaxation times calculation and statistical texture features calculation. An important aspect of analysis of articular cartilage relaxation times changing is illustrated in the experimental part. The experimental part of the publication also describes the dependence between organic structure and relaxation times. The proposed approach the obtained results can be useful for early OA diagnostics.
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    Development of methods for analysis of knee articular cartilage degeneration by magnetic resonance imaging data
    (2017-03-23) Suponenkovs, Artjoms; Glazs, Aleksandrs; Platkajis, Ardis; Rīga Stradiņš University
    The aim of this paper is to describe the new methods for analyzing knee articular cartilage degeneration. The most important aspects regarding research about magnetic resonance imaging, knee joint anatomy, stages of knee osteoarthritis, medical image segmentation and relaxation times calculation. This paper proposes new methods for relaxation times calculation and medical image segmentation. The experimental part describes the most important aspect regarding analysing of articular cartilage relaxation times changing. This part contains experimental results, which show the codependence between relaxation times and organic structure. These experimental results and proposed methods can be helpful for early osteoarthritis diagnostics.
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    Human herpesvirus 6 and 7 reactivation and disease activity in multiple sclerosis
    (2011) Nora-Krukle, Zaiga; Chapenko, Svetlana; Logina, Inara; Millers, Andrejs; Platkajis, Ardis; Murovska, Modra; Institute of Microbiology and Virology; Department of Neurology and Neurosurgery; Department of Radiology
    Recent studies have focused on the associations between human herpesvirus 6 (HHV-6) and human herpesvirus 7 (HHV-7), and multiple sclerosis (MS). The aim of this study was to investigate the associations between HHV-6 and HHV-7 reactivation and MS disease activity, and interleukin 12 (IL-12) and tumor necrosis factor α (TNF-α) production. Material and Methods. The frequency of plasma viremia by nested polymerase chain reaction and transcription of viral mRNA in peripheral blood mononuclear cells by reverse transcriptasepolymerase chain reaction (RT-PCR) of 14 relapsing/remitting (RR) and 14 secondary progressive (SP) MS patients were studied in comparison with clinical manifestation of the disease. Serum concentrations of cytokines IL-12 and TNF-α were analyzed by enzyme-linked immunosorbent assay. Results. Plasma samples from 25 of the 28 MS patients with estimated latent/persistent HHV-6 and/or HHV-7 infection were examined during relapse and remission/relative remission. HHV-6 reactivation was found in 4 of the 7 RRMS and 4 of the 7 SPMS patients, and HHV-7 reactivation was identified in 3 of the 7 RRMS and 1 of the 7 SPMS patients (all in relapse). In 2 of the 3 RRMS patients without viremia in relapse, HHV-6 mRNA transcription was detected. In RRMS and SPMS patients with active HHV-6 and HHV-7 infection in relapse, the serum concentrations of IL-12 and TNF-α were significantly higher than in those with latent virus infection. Conclusions. HHV-6 and HHV-7 reactivation could be implicated in the exacerbation of MS via activation of Th1 lymphocyte subsets.
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    White matter abnormalities in methcathinone abusers with an extrapyramidal syndrome
    (2010-12) Stepens, Ainars; Stagg, Charlotte Jane; Platkajis, Ardis; Boudrias, Marie Hélène; Johansen-Berg, Heidi; Donaghy, Michael; Department of Neurology and Neurosurgery; Department of Radiology
    We examined white matter abnormalities in patients with a distinctive extrapyramidal syndrome due to intravenous methcathinone (ephedrone) abuse. We performed diffusion tensor imaging in 10 patients and 15 age-matched controls to assess white matter structure across the whole brain. Diffuse significant decreases in white matter fractional anisotropy, a diffusion tensor imaging metric reflecting microstructural integrity, occurred in patients compared with controls. In addition, we identified two foci of severe white matter abnormality underlying the right ventral premotor cortex and the medial frontal cortex, two cortical regions involved in higher-level executive control of motor function. Paths connecting different cortical regions with the globus pallidus, the nucleus previously shown to be abnormal on structural imaging in these patients, were generated using probabilistic tractography. The fractional anisotropy within all these tracts was lower in the patient group than in controls. Finally, we tested for a relationship between white matter integrity and clinical outcome. We identified a region within the left corticospinal tract in which lower fractional anisotropy was associated with greater functional deficit, but this region did not show reduced fractional anisotropy in the overall patient group compared to controls. These patients have widespread white matter damage with greatest severity of damage underlying executive motor areas.