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  • Author: V. Juráš x
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The Relationship between MR Parameters and Biomechanical Quantities of Loaded Human Articular Cartilage in Osteoarthritis: An In-Vitro Study

The aim of this study was to assess the changes in MRI parameters during applied load directly in MR scanner and correlate these changes with biomechanical parameters of human articular cartilage. Cartilage explants from patients who underwent total knee replacement were examined in the micro-imaging system in 3T scanner. Respective MRI parameters (T1 without- and T1 with contrast agent as a marker of proteoglycan content, T2 as a marker of collagen network anisotropy and ADC as a measure of diffusivity) were calculated in pre- and during compression state. Subsequently, these parameters were compared to the biomechanical properties of articular cartilage, instantaneous modulus (I), equilibrium modulus (Eq) and time of tissue relaxation (τ). Significant load-induced changes of T2 and ADC were recorded. High correlation between T1Gd and I (r = 0.6324), and between ADC and Eq (r = -0.4884) was found. Multi-parametric MRI may have great potential in analyzing static and dynamic biomechanical behavior of articular cartilage in early stages of osteoarthritis (OA).

Phased Array Receiving Coils for Low Field Lungs MRI: Design and Optimization

Recent techniques of radiofrequency (RF) probes and preamplifiers in Magnetic Resonance Imaging (MRI) developments almost reached the physical limits of signal to noise ratio (SNR). More improvements in speed accelerations of data acquisition are very difficult to achieve. One exception, called RF phased array coils, is recently being developed very progressively. The approach is conceptually similar to phased array used in radar techniques; hence it is usually called MRI phased array coils. It is necessary to ensure independence of the individual coil channels in the array by the coil and preamp decoupling and the coil geometry optimization to get maximum benefits from this technique. Thus, the qualitative design and method for optimization of geometric properties of the coil elements in phased arrays, with aim to increase SNR, minimize the G-factor and to limit noise correlation, are proposed in this paper. By the finite element method (FEM) simulations, we obtained the sensitivity maps and inductances of the coils. The introduced program primarily calculates the Sensitivity Encoding (SENSE) G-factor along with other parameters that can be derived from sensitivity maps. By the proposed optimization algorithm, the program is capable to calculate the optimal values of the geometric coil parameters in a relatively small number of iterations.

Abstract

The aim of this work was to evaluate the presence of Cysticercus bovis of slaughtered cattle in a Croatian slaughterhouse between 2005 and 2010. In total, 203 166 carcasses and organs were examined, of which in 228 C. bovis was found (0.11 %). The highest number of cysticercosis was found in cows (0.69 %, n = 13 605), then in steers (0.093 %; n = 134 212), and the lowest in calves (0.014 %; n = 55 349). Among the 228 positive specimens, 129 (56.57 %) came from rural estates and 99 (43.43 %) from farms. The ratio of invaded steers from rural estates (n = 2 790) and from farm breed (n = 131 422) was 1.075 %: 0.064 %, calves (n = 316 and n = 55 033) 0.316 %: 0.012 %, and cows (n = 8 985 and n = 4 620) 097 %: 0.15 %. The number of cysticercosis invaded cattle decreased from the initial 0.37 % to 0.07 %. Despite low prevalence, we consider that each positive result requires an individual epidemiologic study in order to decrease the risk even more.

Abstract

Anthropological examinations were performed on skeletal material from four barrow necropolises located in the Yampil Region (Ukraine) and dated to the Eneolithic, Bronze Age and Iron Age. The purpose of the examinations was the determination of sex and age at death of individuals, reconstruction of their stature and assessment of their status of health. The examinations covered 61 individuals: 17 children and 44 adults. Their health status was assessed using four common indicators: linear enamel hypoplasia, cribra orbitalia, porotic hyperostosis and dental caries.