Positrons are widely used in molecular imaging through the positron emission tomography (PET) imaging technique. However PET only reconstruct the distribution of the positron emitting radioisotopes, ...and because the <inline-formula> <tex-math notation="LaTeX">\beta ^{+} </tex-math></inline-formula> isotopes are linked to a vector molecule, the distribution of <inline-formula> <tex-math notation="LaTeX">\beta ^{+} </tex-math></inline-formula> isotopes is correlated to the distribution of a given biological function. Positron-electron annihilation can transit through a meta-stable called positronium, which can exist in two spin states: 1) the single state-parapositronium and 2) the triplet state-orthopositronium. The orthopositronium lifetime <inline-formula> <tex-math notation="LaTeX">(\tau _{\mathrm {oPs}}) </tex-math></inline-formula>, formation probabilities and decay modes are sensitive to the physical and chemical state of the neighboring medium and could therefore provide information on the tissues themselves during a PET acquisition. However, traditional PET only relies on the detection of the two annihilation photons, therefore the lifetime and annihilation higher-multiplicity annihilations are not accessible to such PET paradigm. This review will present some of the use cases of positronium as a specific signature for event selection in astrophysics and particle physics, and as a probe for the microscopic state of materials and tissues. These usages of positronium highlight the interest for positronium for diagnostic in medical science, the projects for using positronium in upcoming PET tomographs are then presented.
The concept of imaging several subjects simultaneously is an active preclinical research topic. In this article, we assessed the imaging capabilities of two positron emission tomograph (PET)/computed ...tomograph (CT) systems based on similar detector technology. The IRIS system is a mice/rat imaging system arranged in two rings of eight detectors each, the more recent IRIS XL 260, dedicated to nonhuman primate (NHP) imaging has a single ring of 16 detectors. Both systems were equipped with standard animal cells (Minerve) and 3-mice adapters. Our objective is to study which of these systems could be more appropriate to perform quantitative high-throughput imaging on mice. Phantoms and 18FFDG tumor-bearing mice acquisitions have been conducted in single- and high-throughput modes using both the IRIS (up to 3 mice) and the IRIS XL-260 PET/CT (up to 6 mice) systems. Image quality phantom results obtained in high-throughput mode show some slight degradation of the recovery coefficient for rods of 1, 2, and 3 mm in diameter compared to the single-mode results, as one would normally expect. Similarly, we observed a decrease in image uniformity between the single- and the high-throughput modes for both the IRIS PET and the IRIS XL-260 PET systems. We performed 18FFDG tumor-bearing mice PET acquisitions with both systems. In order to estimate the quantification differences in all the studied configurations, we calculate the ratios between the %ID/g values extracted from the PET images and the ex-vivo values. In single-mode acquisitions, ratios of 0.94 ± 0.09 and 0.83 ± 0.08 were obtained for the IRIS and the IRIS XL-260 PET systems, respectively. In high-throughput mode, ratios of 0.78 ± 0.12 and 0.73 ± 0.13 were obtained for the IRIS and the IRIS XL-260 PET systems, respectively. The difference in %ID/g between static acquisitions and ex-vivo value is not statistically significant (<inline-formula> <tex-math notation="LaTeX">p </tex-math></inline-formula>-value > 0.1) for both PET systems in single mode, as well as for the IRIS system in the high-throughput mode. We noted a slightly higher statistical difference between static acquisitions and ex-vivo values for the IRIS XL-260 system with a <inline-formula> <tex-math notation="LaTeX">p </tex-math></inline-formula>-value of 0.015. Phantoms and in-vivo studies have made it possible to highlight the capability of the two systems to perform high-throughput acquisitions. Our results suggest that the IRIS system configuration may be the most suitable when aiming for quantitative high-throughput mice imaging. The large transverse field of view of the IRIS XL-260 makes it possible to image a greater number of mice simultaneously, which may be useful in specific cases, such as studies using an expensive radiotracer and/or with a short half-life. However, the IRIS PET/CT offers a full axial coverage of the animals and a higher sensitivity.
Mesothelioma is a rare and aggressive malignant neoplasm arising from mesothelial cells, which occasionally manifests recurrent fusions. EWSR1/FUS-CREB, YY1, MAP3K8, NR4A3, and ALK-rearranged ...proliferations have been reported in limited series with no clear histological or clinical correlations, limiting clinicians’ ability to assess prognosis and integrate these new entities into therapeutic decisions. The aim of this study was to better characterize these rearranged proliferations histologically, molecularly, and clinically.
Clinical, pathological, and comprehensive transcriptome and mutation data were collected for each case.
A total of 41 tumors were included, encompassing 7 ALK, 10 MAP3K8, 4 NR4A3, 8 ESWR1/FUS::ATF1, 8 EWSR1::YY1, and 4 SUFU-fused cases. We found a female predominance, except for cases harboring NR4A3 and SUFU; and most patients were around 60 years of age, but those harboring ALK or EWSR1/FUS::ATF1 gene fusions were younger. Each group exhibited distinct histological, immunohistochemical, molecular features, and oncological courses. Specifically, MAP3K8 and ALK presented PAX8+ papillary proliferations, ESWR1/FUS::ATF1 and EWSR1::YY1 displayed angiomatoid fibrous histiocytoma-like patterns, while SUFU showcased ‘tissue culture’-like spindle cell proliferation. Poor prognosis factors were the pleural site, male sex, Ki67 ≥10%, and ESWR1/FUS::ATF1 or SUFU gene fusions.
This study significantly broadens the spectrum of mesothelial tumors associated with fusions, offering insight into novel epithelioid (mesothelial) proliferations with distinctive histological appearances, molecular profiles, and prognoses to guide adapted treatments for patients.
•Investigation histologically, molecularly, and clinically of 41 peritoneal and pleural rearranged mesotheliomas and neoplasms.•Each group exhibited distinct histological, immunohistochemical, molecular features, and overall survival.•A female predominance was found, except for cases of NR4A3 and SUFU fusion.•Most patients were aged 60 years, but those harboring ALK or EWSR1/FUS::ATF1 gene fusions were younger.•A longer overall survival was found for female sex, peritoneum or tunica vaginalis testis site, ALK, or NR4A3 fusions, and Ki67 <10%.
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A
bstract
The Double Chooz experiment measures the neutrino mixing angle
θ
13
by detecting reactor
ν
¯
e
via inverse beta decay. The positron-neutron space and time coincidence allows for a sizable ...background rejection, nonetheless liquid scintillator detectors would profit from a positron/electron discrimination, if feasible in large detector, to suppress the remaining background. Standard particle identification, based on particle dependent time profile of photon emission in liquid scintillator, can not be used given the identical mass of the two particles. However, the positron annihilation is sometimes delayed by the ortho-positronium (o-Ps) metastable state formation, which induces a pulse shape distortion that could be used for positron identification. In this paper we report on the first observation of positronium formation in a large liquid scintillator detector based on pulse shape analysis of single events. The o-Ps formation fraction and its lifetime were measured, finding the values of 44 % ±12 % (sys.) ±5 % (stat.) and 3.68 ns ±0.17 ns (sys.) ±0.15 ns (stat.) respectively, in agreement with the results obtained with a dedicated positron annihilation lifetime spectroscopy setup.
We present the waveform digitiser used in the Double Chooz experiment. We describe the hardware and the custom-built firmware specifically developed for the experiment. The performance of the device ...is tested with regards to digitising low light level signals from photomultiplier tubes and measuring pulse charge. This highlights the role of quantisation effects and leads to some general recommendations on the design and use of waveform digitisers.
The MiniBooNE experiment at Fermilab reports a total excess of 638.0 ± 52.1 (stat .) ± 122.2 (syst.) electronlike events from a data sample corresponding to 18.75 × 10 20 protons-on-target in ...neutrino mode, which is a 46% increase in the data sample with respect to previously published results and 11.27 × 10 20 protons-on-target in antineutrino mode. The overall significance of the excess, 4.8σ, is limited by systematic uncertainties, assumed to be Gaussian, as the statistical significance of the excess is 12.2σ. The additional statistics allow several studies to address questions on the source of the excess. First, we provide two-dimensional plots in visible energy and the cosine of the angle of the outgoing lepton, which can provide valuable input to models for the event excess. Second, we test whether the excess may arise from photons that enter the detector from external events or photons exiting the detector from π 0 decays in two model independent ways. Beam timing information shows that almost all of the excess is in time with neutrinos that interact in the detector. The radius distribution shows that the excess is distributed throughout the volume, while tighter cuts on the fiducial volume increase the significance of the excess. The data likelihood ratio disfavors models that explain the event excess due to entering or exiting photons.
We report on the first measurement of flux-integrated single differential cross sections for charged-current (CC) muon neutrino (νμ) scattering on argon with a muon and a proton in the final state, ...Ar40 (νμ,μp)X. The measurement was carried out using the Booster Neutrino Beam at Fermi National Accelerator Laboratory and the MicroBooNE liquid argon time projection chamber detector with an exposure of 4.59×1019 protons on target. Events are selected to enhance the contribution of CC quasielastic (CCQE) interactions. The data are reported in terms of a total cross section as well as single differential cross sections in final state muon and proton kinematics. We measure the integrated per-nucleus CCQE-like cross section (i.e., for interactions leading to a muon, one proton, and no pions above detection threshold) of (4.93±0.76stat±1.29sys)×10−38 cm2, in good agreement with theoretical calculations. The single differential cross sections are also in overall good agreement with theoretical predictions, except at very forward muon scattering angles that correspond to low-momentum-transfer events.
Neutrinos were assumed to be massless particles until the discovery of the neutrino oscillation process. This phenomenon indicates that the neutrinos have non-zero masses and the mass eigenstates ...(ν1, ν2, ν3) are mixtures of their flavour eigenstates (νe, νμ, ντ). The oscillations between different flavour eigenstates are described by three mixing angles (θ12, θ23, θ13), two differences of the squared neutrino masses of the ν2/ν1 and ν3/ν1 pairs and a charge conjugation parity symmetry violating phase δCP. The Double Chooz experiment, located near the Chooz Electricité de France reactors, measures the oscillation parameter θ13 using reactor neutrinos. Here, the Double Chooz collaboration reports the measurement of the mixing angle θ13 with the new total neutron capture detection technique from the full data set, yielding sin2(2θ13) = 0.105 ± 0.014. This measurement exploits the multidetector configuration, the isoflux baseline and data recorded when the reactors were switched off. In addition to the neutrino mixing angle measurement, Double Chooz provides a precise measurement of the reactor neutrino flux, given by the mean cross-section per fission 〈σf〉 = (5.71 ± 0.06) × 10−43 cm2 per fission, and reports an empirical model of the distortion in the reactor neutrino spectrum.The Double Chooz collaboration reports the neutrino oscillation parameter θ13 from a measurement of the disappearance of reactor anti-electron neutrinos with the total neutron capture technique.
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