First Positronium Lifetime Imaging using 52Mn and 55Co with a plastic-based PET scanner
M. Das, S. Sharma, E. Y. Beyene, A. Bilewicz, J. Choiński, N. Chug, C. Curceanu, E. Czerwiński, J. Hajduga, S. Jalali, K. Kacprzak, T. Kaplanoglu, Ł. Kapłon, K. Kasperska, A. Khreptak, G. Korcyl, T. Kozik, K. Kubat, D. Kumar, S. Kumar Kundu, A. Kunimmal Venadan, E. Lisowski, F. Lisowski, J. Medrala-Sowa, S. Moyo, W. Mryka, S. Niedźwiecki, A. Pandey, P. Pandey, S. Parzych, A. Porcelli, B. Rachwał, M. Rädler, N. Rathod, N. Razzaq, A. Rominger, K. Shi, M. Skurzok, M. Słotwiński, A. Stolarz, T. Szumlak, P. Tanty, K. Tayefi Ardebili, S. Tiwari, K. Valsan Eliyan, R. Walczak, E. Ł. Stępień, P. Moskal
abstract
This study demonstrates applicability of 52Mn and 55Co radionuclides for positronium imaging. Positronium Lifetime Imaging
(PLI) extends positron emission tomography by using the lifetime of positronium atoms as a probe of tissue molecular
architecture. However, its practical use requires ?+ emitters that also provide an additional prompt ? ray to mark the positron creation time. In this work, we report the first PLI measurements performed with 52Mn and 55Co using the modular J-PET. Four samples were studied in each experiment: two Certified Reference Materials (polycarbonate and fused silica) and two
human tissues (cardiac myxoma and adipose). The selection of PLI events was based on the registration of two 511 keV
annihilation photons and one prompt gamma in triple coincidence. From the resulting lifetime spectra we extracted the mean
ortho-positronium lifetime ?oPs and the mean positron lifetime ?Tmean for each sample. The measured values of ?oPs in
polycarbonate using both isotopes matches well with the certified reference values. Furthermore, 55Co reproduced identical
results for fused-silica measurements at their respective uncertainty levels. In contrast, measurements with 52Mn in fused silica show a minor deviation, which could be caused by the Parafilm spacer. In myxoma and adipose tissue, the reduced ?oPs values are mainly linked to the long storage history of the samples rather than to the choice of isotope. Comparing peak-to-background ratios and spectral purity, 55Co provides cleaner PLI data under the same experimental conditions. Although 52Mn offers a longer half-life and a multi gamma cascade enhancing ?+ + ? coincidences, but at the expense of higher background. In this study, we demonstrate that the applied selection criteria on the data measured with the modular J-PET can be used for PLI studies even with radionuclides with complex decay patterns.
Cryo-TEM and NTA Characterisation of Hyperglycemia-Induced Variability in Morphology and Size Distribution of EVs
M. Słotwiński, E. Stępień, A. Kyzioł, M. Rawski
abstract
Introduction: Extracellular vesicles (EVs) are membrane-bound structures that play a crucial role in intercellular communication and molecular transport. Due to their biological functions, EVs hold great potential as a novel diagnostic tool or as the targeted drug carriers in anticancer therapies. Elevated glucose concentrations affect cellular metabolism, thereby modifying the composition of the EVs and their lipid bilayer. This, in turn, can influence EVs' properties and morphology, which is important in their function.
Hypothesis: Hyperglycemic conditions, by altering the composition and metabolism of EVs, influence their size distribution and physicochemical properties.
Objective: Visualisation and size distribution comparison of EVs isolated from normoglycemic (NG) and hyperglycemic (HG) conditions.
Methods: Two complementary methods based on different physical principles were applied and compared in terms of their applicability: nanoparticle tracking analysis (NTA) and cryo- -transmission electron microscopy (Cryo-TEM). In this study, 1.1B4 cells were cultured in normo- (NG, 5 mM glucose) and hyperglycemic (HG, 25 mM glucose) conditions.
Results: The mean hydrodynamic EV size under hyperglycemic conditions (236 ? 28 nm) was slightly higher than the control (209 ? 43 nm; Paired Sample Wilcoxon Signed Test, p = 0.05). Physical EV sizes (Cryo-TEM), as well as mode hydrodynamic sizes (NTA) were consistent and not affected by glucose concentration. In contrast to NTA, Cryo-TEM is a more precise technique for real-size distribution analysis, whereas NTA provides a rapid and cost-effective assessment of hydrodynamic radii. The theoretical level of detection of NTA for EVs was close to what was observed in results.
Conclusions: Hyperglycemic conditions slightly influenced only the mean hydrodynamic radius of EVs, indicating effects on EV corona size and the biogenesis of large EVs (lEVs).
