Simulating NEMA characteristics of the modular total-body J-PET scanner-an economic total-body PET from plastic scintillators

The purpose of the presented research is estimation of the performance characteristics of the economic total-body Jagiellonian-PET system (TB-J-PET) constructed from plastic scintillators. The characteristics are estimated according to the NEMA NU-2-2018 standards utilizing the GATE package. The simulated detector consists of 24 modules, each built out of 32 plastic scintillator strips (each with cross section of 6 mm times 30 mm and length of 140 or 200 cm) arranged in two layers in regular 24-sided polygon circumscribing a circle with the diameter of 78.6 cm. For the TB-J-PET with an axial field-of-view (AFOV) of 200 cm, a spatial resolutions (SRs) of 3.7 mm (transversal) and 4.9 mm (axial) are achieved. The noise equivalent count rate (NECR) peak of 630 kcps is expected at 30 kBq cc^-1. Activity concentration and the sensitivity at the center amounts to 38 cps kBq^-1. The scatter fraction (SF) is estimated to 36.2 %. The values of SF and SR are comparable to those obtained for the state-of-the-art clinical PET scanners and the first total-body tomographs: uExplorer and PennPET. With respect to the standard PET systems with AFOV in the range from 16 to 26 cm, the TB-J-PET is characterized by an increase in NECR approximately by factor of 4 and by the increase of the whole-body sensitivity by factor of 12.6 to 38. The time-of-flight resolution for the TB-J-PET is expected to be at the level of CRT = 240 ps full width at half maximum. For the TB-J-PET with an AFOV of 140 cm, an image quality of the reconstructed images of a NEMA IEC phantom was presented with a contrast recovery coefficient and a background variability parameters. The increase of the whole-body sensitivity and NECR estimated for the TB-J-PET with respect to current commercial PET systems makes the TB-J-PET a promising cost-effective solution for the broad clinical applications of total-body PET scanners. TB-J-PET may constitute an economic alternative for the crystal TB-PET scanners, since plastic scintillators are much cheaper than BGO or LYSO crystals and axial arrangement of the strips significantly reduces the costs of readout electronics and SiPMs.

Feasibility study of the positronium imaging with the J-PET tomograph

A detection system of the conventional PET tomograph is set-up to record data from [Formula: see text] annihilation into two photons with energy of 511 keV, and it gives information on the density distribution of a radiopharmaceutical in the body of the object. In this paper we explore the possibility of performing the three gamma photons imaging based on ortho-positronium annihilation, as well as the possibility of positronium mean lifetime imaging with the J-PET tomograph constructed from plastic scintillators. For this purposes simulations of the ortho-positronium formation and its annihilation into three photons were performed taking into account distributions of photons' momenta as predicted by the theory of quantum electrodynamics and the response of the J-PET tomograph. In order to test the proposed ortho-positronium lifetime image reconstruction method, we concentrate on the decay of the ortho-positronium into three photons and applications of radiopharmaceuticals labeled with isotopes emitting a prompt gamma. The proposed method of imaging is based on the determination of hit-times and hit-positions of registered photons which enables the reconstruction of the time and position of the annihilation point as well as the lifetime of the ortho-positronium on an event-by-event basis. We have simulated the production of the positronium in point-like sources and in a cylindrical phantom composed of a set of different materials in which the ortho-positronium lifetime varied from 2.0 ns to 3.0 ns, as expected for ortho-positronium created in the human body. The presented reconstruction method for total-body J-PET like detector allows to achieve a mean lifetime resolution of  ∼40 ps. Recent positron annihilation lifetime spectroscopy measurements of cancerous and healthy uterine tissues show that this sensitivity may allow to study the morphological changes in cell structures.

The increased plasma C-reactive protein and interleukin-6 levels in patients undergoing coronary artery bypass grafting surgery are associated with the interleukin-6−174G > C gene polymorphism

Background

The interleukin-6 (IL-6) promoter −174G/C polymorphism (rs1800795) is associated with enhanced systemic inflammatory response to injury. However, data on the effect of this polymorphism on inflammatory markers in patients undergoing coronary artery bypass grafting surgery (CABG) are inconsistent. The aim of our study was to investigate whether −174G/C IL-6 polymorphism affects plasma IL-6 and C-reactive protein (CRP) concentrations in patients undergoing CABG.

Methods

A total of 179 consecutive white patients (77% men, aged 65 ± 8.6 standard deviation [SD] y) scheduled for elective isolated CABG were studied. Pre- and postoperative CRP and IL-6 levels were analysed in relation to the 174G/C IL-6 polymorphism determined by using TaqMan single-nucleotide polymorphism genotyping technique.

Results

The genotype distribution was as follows: GG –46 (26%), GC –93 (52%) and CC –40 (22%). The C allele carriers had higher baseline CRP (4.1 ± 0.35 versus 2.4 ± 0.59 mg/L, P = 0.02) and IL-6 levels (3.0 ± 0.17 versus 2.2 ± 0.3 pg/mL, P = 0.02) than GG patients. Five to seven days after CABG, CRP levels rose by 54% ( P = 0.03), and IL-6 levels tended to be higher ( P = 0.07) in −174C allele carriers than the non-carriers. There were no associations between −174G/C IL-6 polymorphism and any demographic-, clinical- or procedure-related variables as well as major adverse cardiovascular events. Multivariate regression analysis, including sex, age, body mass index, hypercholesterolaemia, smoking, hypertension diabetes, identified CG + CC genotype as the only independent predictor of preoperative CRP and IL-6 levels.

Conclusions

The presence of the −174C allele determines to some extent higher plasma CRP and IL-6 concentrations pre- and postoperatively in CABG patients.