79 research outputs found
Stau relic density at the Big-Bang nucleosynthesis era consistent with the abundance of the light element nuclei in the coannihilation scenario
We calculate the relic density of stau at the beginning of the Big-Bang
Nucleosynthesis (BBN) era in the coannihilation scenario of minimal
supersymmetric standard model (MSSM). In this scenario, stau can be long-lived
and form bound states with nuclei. We put constraints on the parameter space of
MSSM by connecting the calculation of the relic density of stau to the
observation of the light elements abundance, which strongly depends on the
relic density of stau. Consistency between the theoretical prediction and the
observational result, both of the dark matter abundance and the light elements
abundance, requires the mass difference between the lighter stau and the
lightest neutralino to be around 100MeV, the stau mass to be 300 -- 400 GeV,
and the mixing angle of the left and right-handed staus to be
.Comment: 9 pages, 5 figures, figure 5 correcte
Possible solution to the Li problem by the long lived stau
Modification of standard big-bang nucleosynthesis is considered in the
minimal supersymmetric standard model to resolve the excessive theoretical
prediction of the abundance of primordial lithium 7. We focus on the stau as a
next-lightest superparticle, which is long lived due to its small mass
difference with the lightest superparticle. It provides a number of additional
decay processes of and . A particularly
important process is the internal conversion in the stau-nucleus bound state,
which destroys the and effectively. We show
that the modification can lead to a prediction consistent with the observed
abundance of .Comment: 6 pages, 5 figure
Big-bang nucleosynthesis with a long-lived charged massive particle including He spallation processes
We propose helium-4 spallation processes induced by long-lived stau in
supersymmetric standard models, and investigate an impact of the processes on
light elements abundances. We show that, as long as the phase space of helium-4
spallation processes is open, they are more important than stau-catalyzed
fusion and hence constrain the stau property.Comment: 12 pages, 4 figures, 1 table, references added, all figures correcte
Added Diagnostic Value of Cerebrospinal Fluid Carcinoembryonic Antigen in a Patient with Leptomeningeal Carcinomatosis as the Initial Manifestation of Gastric Cancer
A 77-year-old woman with no history of malignancy presented with anorexia and bilateral lower extremity weakness. Her consciousness level worsened daily, so we performed a lumbar puncture. Cerebrospinal fluid (CSF) analysis indicated meningitis, but three rounds of CSF cytology showed no malignant cells. The patient’s carcinoembryonic antigen (CEA) level was highly elevated in CSF, but normal in serum. Through gadolinium-enhanced brain/spinal magnetic resonance imaging and gastrointestinal endoscopy, she was diagnosed with leptomeningeal carcinomatosis (LC) from gastric cancer. CEA level in CSF facilitated the diagnosis of LC from gastric cancer because there were no malignant cells on CSF cytology
Magnetic Field Effect on Electron Transfer Process in Electrochemical Reaction(Crystal Growth, Chemical Reaction and Biology)
A new method with MHD electrode (MHDE) to analyze the electrochemical reaction under the magnetic field is applied to the copper reduction. The Tafel plots obtained at the magnetic field up to 13T show that there is no change in the slopes but drastic decrease of the current density in comparison with the results in the no or low magnetic field
Imaging of Cardiomyopathy
Background: In cardiomyopathy, 99mTc-MIBI washout can reflect mitochondrial dysfunction and late gadolinium enhancement (LGE) on cardiac magnetic imaging (MRI) is associated with tissue fibrosis. We sought to determine the relationship between 99mTc-MIBI uptake, 99mTc-MIBI washout, and LGE on MRI in patients with cardiomyopathy.
Methods: Twenty-one patients underwent rest myocardial perfusion scintigraphy at 45 minutes (early) and 4 hours (delayed) after intravenous 99mTc-MIBI administration and cardiac MRI. We assessed myocardial perfusion, 99mTc-MIBI washout, and LGE. We divided the left ventricle (LV) wall into 16 segments using a polar map. Then, we classified each segment into 5 groups according to 99mTc-MIBI uptake in early-rest images and washout. Additionally, we created a contingency table based on LGE presence/absence in the groups.
Results: We evaluated 336 segments in 21 patients. 99mTc-MIBI uptake was decreased in 168 segments in the early-rest 99mTc-MIBI images. 99mTc-MIBI washout was observed in 108 segments with either normal perfusion or reduced perfusion in the early-rest 99mTc-MIBI images. LGE was positive in 104 segments. A contingency table analysis with Fisher’s exact test showed that LGE was observed significantly more frequently in the segments with decreased 99mTc-MIBI uptake (p < 0.001). In segments without a decreased 99mTc-MIBI uptake, there was a significant correlation between increased 99mTc-MIBI washout and the presence of LGE (p = 0.033).
Conclusions: In cardiomyopathy, the mitochondrial dysfunction in the early stage is shown as 99mTc-MIBI washout, and fibrotic changes in the myocardium in advanced stages are shown as LGE on cardiac MRI. The severity of myocardial damage and the clinical stage of cardiomyopathy can be evaluated using multimodal imaging
Effect of malnutrition on FDG PET
Objective
18F-FDG PET/CT is a hybrid imaging method widely used as a useful, noninvasive imaging modality for evaluating various neoplastic diseases. When assessing the tumor uptake, the liver and the mediastinal blood pool are often used as a reference region. In daily clinical practice, the 18F-FDG uptake in the liver sometimes appears to decrease on PET images of patients with malnutrition. The purpose of this study was to investigate whether or not the liver 18F-FDG uptake is decreased in patients with malnutrition.
Methods
We retrospectively analyzed 246 patients who underwent 18F-FDG PET/CT from January 2018 to June 2018 and whose blood serum albumin was measured within 1 month of PET/CT. We compared the liver uptake and mediastinal blood uptake of patients with low serum albumin level (< 4.0 g/dl) and hypoalbuminemia (< 3.5 g/dl) with those with a normal serum albumin level (≥ 4.0 g/dl). Correlations between the liver and mediastinal blood uptake and the serum albumin level were also calculated.
Results
The maximum standardized uptake value (SUVmax) and mean standardized uptake value (SUVmean) of the liver in 117 patients with low serum albumin were 3.1 ± 0.5 and 2.3 ± 0.3, respectively, while they were 2.9 ± 0.4, 2.0 ± 0.3 in 29 patients with hypoalbuminemia; these values were all significantly lower than the respective ones (3.4 ± 0.5, 2.5 ± 0.4) in 129 patients with normal serum albumin (all p < 0.001). The SUVmean of the mediastinal blood uptake in patients with hypoalbuminemia and normal serum albumin were 1.6 ± 0.2 and 1.7 ± 0.3, respectively (p = 0.053). The serum albumin level demonstrated a significantly positive, moderate correlation with the liver SUVmean, showing a regression line of y = 0.31x + 1.1 (r = 0.41, p < 0.001).
Conclusion
The liver 18F-FDG uptake tended to decrease in patients with hypoalbuminemia. In the patients with malnutrition, the mediastinal blood pool may be more stable reference than the liver for evaluating the tumor activity because hypoalbuminemia is considered to less strongly influence the mediastinal blood pool than that in the liver
The diagnostic ability of SPECT/CT fusion imaging for gastrointestinal bleeding : a retrospective study
Background
Blood loss from the gastrointestinal tract can be an acute and life-threatening event. For the treatment of gastrointestinal bleeding, it is important to accurately detect gastrointestinal bleeding and to localize the sites of bleeding. The purpose of this study was to retrospectively assess the capabilities of SPECT/CT in the diagnosis of gastrointestinal bleeding by a comparison with planar imaging alone as well as planar and SPECT.
Methods
We conducted a retrospective analysis of 20 patients (21 examinations) who underwent gastrointestinal bleeding scintigraphy in the past 7 years and in whom the bleeding site was identified by endoscopy or capsule endoscopy, or in whom no evidence of gastrointestinal bleeding was identified during the clinical course. Five patients (5 examinations) were diagnosed by planar imaging (planar group). Eight patients (9 examinations) were diagnosed by planar imaging and SPECT (planar + SPECT group). Seven patients (7 examinations) were diagnosed by planar imaging and SPECT/CT (planar + SPECT/CT group). We calculated the diagnostic ability of each method in detecting the presence of bleeding, as well as the ability of each method to identify the sites of bleeding. The sensitivity, specificity, and accuracy of the methods were compared.
Results
The diagnostic ability of the three imaging methods in detecting the presence of gastrointestinal bleeding was as follows. Planar imaging showed 100% sensitivity (3/3), 100% specificity (2/2), and 100% accuracy (5/5). Planar + SPECT imaging showed 85.7% sensitivity (6/7), 100% specificity (2/2), and 88.9% accuracy (8/9). Planar + SPECT/CT imaging showed 100% sensitivity (6/6), 100% specificity (1/1), and 100% accuracy (7/7). The diagnostic ability of the three modalities in detecting the site of bleeding was as follows: planar, 33.3% (1/3); planar + SPECT, 71.4% (5/7); and planar + SPECT/CT, 100% (6/6).
Conclusions
All 3 imaging methods showed good accuracy in detecting the presence of gastrointestinal bleeding. The addition of SPECT or SPECT/CT made the anatomical position of the uptake clear and contributed to the localization of the site of gastrointestinal bleeding. Planar + SPECT/CT imaging therefore showed the highest diagnostic ability for detecting the site of gastrointestinal bleeding
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