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16 results on '"Pierzchała, Katarzyna"'

1. Fast 3D 31P B1+ mapping with a weighted stack of spiral trajectory at 7 Tesla

Author

Widmaier, Mark, Kaiser, Antonia, Baup, Salome, Wenz, Daniel, Pierzchala, Katarzyna, Xiao, Ying, Huang, Zhiwei, Jiang, Yun, and Xin, Lijing

Subjects
Physics - Medical Physics
Abstract

Purpose: Phosphorus Magnetic Resonance Spectroscopy (31P MRS) enables non-invasive assessment of energy metabolism, yet its application is hindered by sensitivity limitations. To overcome this, often high magnetic fields are used, leading to challenges such as spatial B_1^+ inhomogeneity and therefore the need for accurate flip angle determination in accelerated acquisitions with short repetition times (T_R). In response to these challenges, we propose a novel short T_R and look-up table-based Double-Angle Method for fast 3D 31P B_1^+ mapping (fDAM). Methods: Our method incorporates 3D weighted stack of spiral gradient echo acquisitions and a frequency-selective pulse to enable efficient B_1^+ mapping based on the phosphocreatine signal at 7T. Protocols were optimised using simulations and validated through phantom experiments. The method was validated in phantom experiments and skeletal muscle applications using a birdcage 1H/31P volume coil. Results: The results of fDAM were compared to the classical DAM (cDAM). A good correlation (r=0.94) was obtained between the two B_1^+ maps. A 3D 31P B_1^+ mapping in the human calf muscle was achieved in about 10 min using a birdcage volume coil, with a 20% extended coverage relative to that of the cDAM (24 min). fDAM also enabled the first full brain coverage 31P 3D B_1^+ mapping in approx. 10 min using a 1 Tx/ 32 Rx coil. Conclusion: fDAM is an efficient method for 31P 3D B_1^+ mapping, showing promise for future applications in rapid 31P MRSI.

Published
2024

2. SPARCQ: A new approach for fat fraction mapping using asymmetries in the phase-cycled bSSFP signal profile

Author

Rossi, Giulia MC, Mackowiak, Adele LC, Hilbert, Tom, Acikgoz, Berk C, Pierzchała, Katarzyna, Kober, Tobias, and Bastiaansen, Jessica AM

Subjects
Physics - Medical Physics
Abstract

Purpose: To develop SPARCQ (Signal Profile Asymmetries for Rapid Compartment Quantification), a novel approach to quantify fat fraction using asymmetries in the phase-cycled bSSFP profile. Methods: SPARCQ uses phase-cycling to obtain bSSFP frequency profiles, which display asymmetries in the presence of fat and water at certain repetition times. For each voxel, the measured signal profile is decomposed into a weighted sum of simulated profiles via multi-compartment dictionary matching. Each dictionary entry represents a single-compartment bSSFP profile with a specific off-resonance frequency and relaxation time ratio. Using the results of dictionary matching, the fractions of the different off-resonance components are extracted for each voxel, generating quantitative maps of water and fat fraction and banding-artifact-free images for the entire image volume. SPARCQ was validated using simulations, experiments in a water-fat phantom and in knees of healthy volunteers. Experimental results were compared with reference proton density fat fractions obtained with 1H-MRS (phantoms) and with multiecho gradient-echo MRI (phantoms and volunteers). SPARCQ repeatability was evaluated in six scan-rescan experiments. Results: Simulations showed that fat fraction quantification is accurate and robust for signal-to-noise ratios greater than 20. Phantom experiments demonstrated good agreement between SPARCQ and gold standard fat fractions. In volunteers, banding-artifact-free quantitative maps and water-fat-separated images obtained with SPARCQ and ME-GRE demonstrated the expected contrast between fatty and non-fatty tissues. The coefficient of repeatability of SPARCQ fat fraction was 0.0512. Conclusion: SPARCQ demonstrates potential for fat quantification using asymmetries in bSSFP profiles, and may be a promising alternative to conventional fat fraction quantification techniques., Comment: 30 pages, 8 figures, submitted to Magnetic Resonance in Medicine

Published
2020
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14. Photocatalytic and phototoxic properties of TiO2-based nanofilaments: ESR and AFM assays.

Author

Pierzchała, Katarzyna, Lekka, Małgorzata, Magrez, Arnaud, Kulik, Andrzej J., Forró, László, and Sienkiewicz, Andrzej

Subjects
*TITANIUM dioxide, *PHOTOCATALYSIS, *TOXICOLOGY, *REACTIVE oxygen species, *NANOTECHNOLOGY
Abstract

There is uncertainty in understanding of the relationship between physico-chemical parameters of nanosized titanium dioxide (nano-TiO2) and its toxicity when brought into contact with living cells. This study provides a multidisciplinary experimental insight into the toxicity and phototoxicity of the custom-made TiO2-based nanowires (TiO2-NWs). We employed electron spin resonance (ESR) to detect reactive oxygen species (ROS) generated in aqueous suspensions of TiO2-NWs and combined these results with atomic force microscopy (AFM) to trace the onset of toxic effects towards human melanoma cells. The cells were treated with low concentrations (∼2.5 μg/ml) of TiO2-NWs and Degussa P25. High-resolution AFM surface topography and cell elasticity measurements revealed toxic effects both in cells incubated with TiO2-NWs in the dark and exposed to the photo-oxidative stress under UVA radiation. In contrast to ROS generation efficacy in the absence of cells in vitro, no direct correlation was found between the physical parameters of nano-TiO2 and cell toxicity. [ABSTRACT FROM AUTHOR]

Published
2012
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15. Synthesis, Characterization, and Photocatalytic Activities of Nanoparticulate N, S-Codoped TiO2Having Different Surface-to-Volume Ratios

Author

Rengifo-Herrera, Julian A., Pierzchała, Katarzyna, Sienkiewicz, Andrzej, Forró, Laszlo, Kiwi, John, Moser, Jacques E., and Pulgarin, Cesar

Abstract

An efficient, visible light active, N, S-codoped TiO2-based photocatalyst was prepared by reacting thiourea with nanoparticulate anatase TiO2. Commercial anatase powders were manually ground with thiourea and annealed at 400 °C in two crucibles with different surface-to-volume ratios (S/V= 20 and 1.5) to prepare two N, S-codoped TiO2materials. The differentiated aeration conditions during the catalyst annealing on the crucibles allowed for different amounts of O2to reach the catalyst surface. The first material, with S/V= 20, herein referred to as D-TKP 102-A, was clear beige colored. The second material, with S/V= 1.5, herein referred to as D-TKP 102-B, was darker and revealed a markedly lower efficiency in Escherichia coliinactivation. The D-TKP 102-A powder presented visible light absorption due to the nitrogen (N) and sulfur (S) doping. X-ray photoelectron spectroscopy signals for this catalyst were observed for N 1s peaks at binding energies of 399.2 and 400.7 eV due to interstitial N-doping or Ti−O−N species. The S 2p were due to SO4−2signals with BE >168 eV and signals at 162.8 and 167.2 eV due to anionic and cationic S-doping, respectively. By fast kinetic spectroscopy, the decay of the electron induced by pulsed light at λ = 450 nm (∼8 ns/laser pulse) was followed for the D-TKP 102-A catalyst. Undoped D-TKP 102 catalyst did not promote the electron in the visible range, and consequently no signal decay could be observed in the latter case. Low-temperature electron spin resonance measurements at 8 K provided evidence for electrons trapped in shallow traps, such as oxygen vacancies, Vo, induced by N, S doped on D-TKP 102-A. The ESR measurements implementing the reactive scavenging with singlet oxygen scavenger, TMP−OH, revealed the production of singlet oxygen (1O2).

Published
2010
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16. Photocatalytic and phototoxic properties of TiO2-based nanofilaments: ESR and AFM assays.

Author

Pierzchała K, Lekka M, Magrez A, Kulik AJ, Forró L, and Sienkiewicz A

Subjects
Catalysis, Cell Line, Tumor, Cell Survival drug effects, Electron Spin Resonance Spectroscopy, Humans, Microscopy, Atomic Force, Microscopy, Electron, Transmission, Oxidative Stress, Photochemical Processes, Nanostructures toxicity, Titanium toxicity
Abstract

There is uncertainty in understanding of the relationship between physico-chemical parameters of nanosized titanium dioxide (nano-TiO(2)) and its toxicity when brought into contact with living cells. This study provides a multidisciplinary experimental insight into the toxicity and phototoxicity of the custom-made TiO(2)-based nanowires (TiO(2)-NWs). We employed electron spin resonance (ESR) to detect reactive oxygen species (ROS) generated in aqueous suspensions of TiO(2)-NWs and combined these results with atomic force microscopy (AFM) to trace the onset of toxic effects towards human melanoma cells. The cells were treated with low concentrations (∼2.5 μg/ml) of TiO(2)-NWs and Degussa P25. High-resolution AFM surface topography and cell elasticity measurements revealed toxic effects both in cells incubated with TiO(2)-NWs in the dark and exposed to the photo-oxidative stress under UVA radiation. In contrast to ROS generation efficacy in the absence of cells in vitro, no direct correlation was found between the physical parameters of nano-TiO(2) and cell toxicity.

Published
2012
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