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SMV-2013-07: Vypracování a ověření metodiky zobrazení a analýzy animálního modelu schizofrenie prostředky magnetické rezonance v poli 9,4 Tesla a proměření dodaného vzorku
Starčuk jr., Zenon ; Dražanová, Eva ; Jiřík, Radovan ; Rychnovský, Jan ; Starčuková, Jana ; Kořínek, Radim
Na základě smlouvy bylo provedeno posouzení zadaného myšího modelu schizofrenie z hlediska možností zobrazení relevantních parametrů struktury a funkce zadavatelem určených orgánů, byly vyhodnoceny možnosti z hlediska požadavků zadavatele, byla navržena a vypracována metodika zobrazení, byly připraveny a validovány projekty pokusů a navržená metodika byla aplikována na sérii 60 zvířat v souladu s platnými projekty pokusů. Původní i statisticky vyhodnocená data byla předána zadavateli.
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The Synthesis, Surface Modification and Stability of SPIO Nanoparticles for MRI Application
Kovář, D. ; Fohlerová, Z. ; Malá, A. ; Jiřík, Radovan ; Starčuk jr., Zenon ; Kalina, M. ; Skládal, P.
The biocompatibility and biodegradability of new magnetic resonance imaging (MRI) contrast agents is high-ly desired. The superparamagnetic iron oxide (SPIO) nanoparticles are suitable candidates for these pur-poses. Here the co-precipitation technique for synthesis of monodispersed SPIO nanoparticles is pre-sented. The critical point of the synthesis is core formation and consequent crystal growth. The conditions for core formation (time, temperature, rate of base addition) were optimised. The nanoparticles were stabilised by either silanisation or polymer coating (cationic chitosan, poly-D-Arg, dextran, gelatine, hyaluronic acid). The stability was investigated in physiological pH, different ionic strength solutions, PBS-albumine solution or blood plasma. The biocompatibility was tested in vitro either in the presence of Saccharomyces cerevisiae or erythrocytes suspension. The size and shape was investigated by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The molecular structures of nanoparticles were investigated by FTIR (Fourier transform infrared spectroscopy). The iron cations were determined using the Prussian blue staining test. The stability of nano-particles was investigated by the zeta potential using the method of electrophoretic light scattering (ELS).
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Some comments on frequency selective excitation in newly proposed MRSI sequences
Starčuk jr., Zenon ; Horký, Jaroslav ; Starčuk, Zenon ; Mlynárik, V. ; Gruber, S. ; Moser, E.
In many pathologies it is desirable to compare the metabolism inside a lesion, near the lesion, and in healthy tissue. The diagnostic value of MRS is enhanced by spectroscopic imaging (MRSI), permitting the simultaneous acquisition of spatially resolved spectra. In this way, assessing metabolic information about different brain regions within a single examination is possible. As with all in vivo spectroscopy, low signal-to-noise ratio (SNR) is the fundamental limiting factor in MRSI due to very low concentrations of metabolites of interest. Proton spectroscopic imaging, however, offers additional technical challenges as compared to single-voxel techniques, especially if acquisition of short echo time (TE<30 ms) is required. Critical to the success of proton MRSI studies of the human brain is the elimination of the very intense water and lipid signals arising from outside the volume of interest (VOI). Water suppression in MRSI can be very problematic in MRSI, in which the achievable degree of water suppression is limited by B.sub.0./sub. and B.sub.1./sub. inhomogeneities and water T.sub.1./sub. variations, invariably present throughout the larger VOIs. Suppression of liquid signals (from bone marrow and subcutaneous fat) is often severely complicated due to the fact that their relaxation behavior differs substantially from that of water. One of the basic approaches used to reduce the undesired contamination if the MRSI signals of interest consists in the use of the STEAM or PRESS selective excitation of the VOI. Both STEAM and PRESS techniques suffer from some drawbacks. STEAM reduces the sensitivity of measurement, PRESS has higher RF power requirements.
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High resolution multivoxel spectroscopy of human brain at 3 Tesla
Mlynárik, V. ; Gruber, S. ; Starčuk, Zenon ; Starčuk jr., Zenon ; Horký, Jaroslav ; Moser, E.
Localisation in in vivo NMR spectroscopy can be achieved using different concepts. Single voxel localized spectroscopy exploits three slice selective pulses defining a cube (or a parallelepiped) in their intersection. By proper combination of spoiling gradients the excited magnetization outside the cube is dephased and does not contribute to the NMR signal. Another way of localisation is combination of slice selection with phase encoding of the NMR signal in the other two dimensions by means of gradient magnetic fields. The latter method is referred to as spectroscopic imaging and provides an array of spectra corresponding to individual voxels defined by the phase encoding. Further subdivision of the voxels is possible by Hadamard encoding of the excitation pulses.
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