Studies have assessed PET by using various tracers to diagnose disease recurrence in patients with previously treated glioma; however, the accuracy of these methods, particularly compared with ...alternative imaging modalities, remains unclear. We conducted a meta-analysis to quantitatively synthesize the diagnostic accuracy of PET and compare it with alternative imaging modalities.
We searched PubMed and Scopus (until June 2011), bibliographies, and review articles. Two reviewers extracted study characteristics, validity items, and quantitative data on diagnostic accuracy. We performed meta-analysis when ≥5 studies were available.
Twenty-six studies were eligible. Studies were heterogeneous in treatment strategies and diagnostic criteria of PET; recurrence was typically suspected by CT or MR imaging. The diagnostic accuracies of (18)F-FDG (n = 16) and (11)C-MET PET (n = 7) were heterogeneous across studies. (18)F-FDG PET had a summary sensitivity of 0.77 (95% CI, 0.66-0.85) and specificity of 0.78 (95% CI, 0.54-0.91) for any glioma histology; (11)C-methionine PET had a summary sensitivity of 0.70 (95% CI, 0.50-0.84) and specificity of 0.93 (95% CI, 0.44-1.0) for high-grade glioma. These estimates were stable in subgroup and sensitivity analyses. Data were limited on (18)F-FET (n = 4), (18)F-FLT (n = 2), and (18)F-boronophenylalanine (n = 1). Few studies performed direct comparisons between different PET tracers or between PET and other imaging modalities.
(18)F-FDG and (11)C-MET PET appear to have moderately good accuracy as add-on tests for diagnosing recurrent glioma suspected by CT or MR imaging. Studies comparing alternative tracers or PET versus other imaging modalities are scarce. Prospective studies performing head-to-head comparisons between alternative imaging modalities are needed.
Interaction between the solar wind and objects in the solar system varies largely according to the settings, such as the existence of a global intrinsic magnetic field and/or thick atmosphere. The ...Moon's case is characterized by the absence of both of them. Low energy ion measurements on the lunar orbit is realized more than 30 years after the Apollo period by low energy charged particle analyzers MAP‐PACE on board SELENE(KAGUYA). MAP‐PACE ion sensors have found that 0.1%∼1% of the solar wind protons are reflected back from the Moon instead of being absorbed by the lunar surface. Some of the reflected ions are accelerated above solar wind energy as they are picked‐up by the solar wind convection electric field. The proton reflection that we have newly discovered around the Moon should be a universal process that characterizes the environment of an airless body.
The suprathermal electrons of ≥20 keV that extend from the hot thermal electron with 2–3 keV temperature are sometimes observed in Earth's magnetosphere in association with reconnection. We study the ...origin of the hot and suprathermal electrons in terms of the kinetic magnetic reconnection process by using the two‐dimensional particle‐in‐cell simulation. We find that the hot and suprathermal electrons can be formed in the nonlinear evolution of a large‐scale magnetic reconnection. The electrons are, at the first stage, accelerated in the elongated, thin, X‐type current sheet. Next the preheated/accelerated electrons are transported to the stronger magnetic field region produced by piling up of magnetic field lines due to colliding of the fast reconnection outflow with the preexisting plasma. In this region they are further accelerated owing to the ∇B drift and the curvature drift. The mirror force of the reconnecting magnetic fields, the effective pitch angle scattering that occurs when the Larmor radius is comparable to the magnetic field line curvature radius, and the broadband waves excited by the Hall electric current are the other important agents to control the particle acceleration.
Neutrinos generated during solar flares remain elusive. However, after 50 years of discussion and search, the potential knowledge unleashed by their discovery keeps the search crucial. Neutrinos ...associated with solar flares provide information on otherwise poorly known particle acceleration mechanisms during a solar flare. For neutrino detectors, the separation between atmospheric neutrinos and solar flare neutrinos is technically encumbered by an energy band overlap. To improve differentiation from background neutrinos, we developed a method to determine the temporal search window for neutrino production during solar flares. Our method is based on data recorded by solar satellites, such as the
Geostationary Operational Environmental Satellite
(GOES), the
Reuven Ramaty High Energy Solar Spectroscopic Imager
(RHESSI), and GEOTAIL. In this study, we selected 23 solar flares above X5.0 class that occurred between 1996 and 2018. We analyzed the light curves of soft X-rays, hard X-rays,
γ
-rays, line
γ
-rays from neutron capture as well as the derivative of soft X-rays. The average search windows are determined as follows: 4178 s for soft X-ray, 700 s for the derivative of soft X-ray, 944 s for hard X-ray (100 – 800 keV),
1
,
586
s for line
γ
-ray from neutron captures, and 776 s for hard X-ray (above 50 keV). This method allows neutrino detectors to improve their sensitivity to solar flare neutrinos.
We study solar wind (SW) entry deep into the near‐Moon wake using SELENE (KAGUYA) data. It has been known that SW protons flowing around the Moon access the central region of the distant lunar wake, ...while their intrusion deep into the near‐Moon wake has never been expected. We show that SW protons sneak into the deepest lunar wake (anti‐subsolar region at ∼100 km altitude), and that the entry yields strong asymmetry of the near‐Moon wake environment. Particle trajectory calculations demonstrate that these SW protons are once scattered at the lunar dayside surface, picked‐up by the SW motional electric field, and finally sneak into the deepest wake. Our results mean that the SW protons scattered at the lunar dayside surface and coming into the night side region are crucial for plasma environment in the wake, suggesting absorption of ambient SW electrons into the wake to maintain quasi‐neutrality.
The CALorimetric Electron Telescope (CALET)on the International Space Station consists of a high-energy cosmic-ray CALorimeter (CAL)and a lower-energy CALET Gamma-ray Burst Monitor (CGBM). CAL is ...sensitive to electrons up to 20 TeV, cosmic-ray nuclei from Z=1 throughZ∼40, and gamma rays over the range1 GeV–10 TeV. CGBM observes gamma rays from 7 keV to 20 MeV. The combined CAL-CGBM instrument has conducted a search for gamma-ray bursts (GRBs)since 2015 October. We report here on the results of a search for X-ray/gamma-ray counterparts to gravitational-wave events reported during the LIGO/Virgo observing run O3. No events have been detected that pass all acceptance criteria. We describe the components, performance, and triggering algorithms of the CGBM—the two Hard X-ray Monitors consisting of LaBr3(Ce)scintillators sensitive to 7 keV–1 MeV gamma rays and a Soft Gamma-ray Monitor BGO scintillator sensitive to 40 keV–20 MeV—and the high-energy CAL consisting of a charge detection module, imaging calorimeter, and the fully active total absorption calorimeter. The analysis procedure is described and upper limits to the time-averaged fluxes are presented.
We present the results of searches for gamma-ray counterparts of the LIGO/Virgo gravitational wave events using CALorimetric Electron Telescope (CALET) observations. The main instrument of CALET, ...CALorimeter (CAL), observes gamma-rays from ∼1 GeV up to 10 TeV with a field of view (FOV) of nearly 2 sr. In addition, the CALET gamma-ray burst monitor views ∼3 sr and ∼2π sr of the sky in the 7 keV-1 MeV and the 40 keV-20 MeV bands, respectively, by using two different crystal scintillators. The CALET observations on the International Space Station started in 2015 October, and here we report analyses of events associated with the following gravitational wave events: GW151226, GW170104, GW170608, GW170814, and GW170817. Although only upper limits on gamma-ray emission are obtained, they correspond to a luminosity of 1049 ∼ 1053 erg s−1 in the GeV energy band depending on the distance and the assumed time duration of each event, which is approximately on the order of luminosity of typical short gamma-ray bursts. This implies that there will be a favorable opportunity to detect high-energy gamma-ray emission in further observations if additional gravitational wave events with favorable geometry will occur within our FOV. We also show the sensitivity of CALET for gamma-ray transient events, which is on the order of 10−7 erg cm−2 s−1 for an observation of 100 s in duration.
The CALorimetric Electron Telescope primary detector (CALET-CAL) is a 30 radiation-length-deep hybrid calorimeter designed for the accurate measurement of high-energy cosmic rays. It is capable of ...triggering on and giving near complete containment of electromagnetic showers from primary electrons and gamma rays from 1 GeV to over 10 TeV. The first 24 months of on-orbit scientific data (2015 November 01-2017 October 31) provide valuable characterization of the performance of the calorimeter based on analyses of the gamma-ray data set in general and bright point sources in particular. We describe the gamma-ray analysis, the expected performance of the calorimeter based on Monte Carlo simulations, the agreement of the flight data with the simulated results, and the outlook for long-term gamma-ray observations with the CAL.
The ‘whistler critical Mach number’, Mcritw, is one of the dimensionless parameters that characterizes collisionless shocks. Originally, it was introduced to indicate the critical point above which ...whistler waves do not propagate upstream. Indeed our analysis of Geotail data at the Earth's bow shock shows intense whistler waves in the sub‐critical regime, MA < Mcritw, but not in the super‐critical regime. In this paper, we further report that Mcritw seems to regulate the electron acceleration efficiency at the shocks. At the shock transition layer it is found that the spectral index Γ of electron energy spectra defined by f(E) ∝ E−Γ is distributed between 3.5 and 5.0 in the sub‐critical regime, while the hardest energy spectra with Γ = 3–3.5 are detected in the super‐critical regime. We discuss a possible relationship between Mcritw and the electron acceleration.
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