MR angiography (MRA) is increasingly used as an alternative to digital subtraction angiography (DSA) to evaluate internal carotid artery (ICA) stenosis. Because MRA is not standardized in data ...acquisition and postprocessing, we sought to evaluate the effects of different acquisition techniques (time-of-flight MRA TOF-MRA) and contrast-enhanced MRA CE-MRA) and postprocessing methods (maximum intensity projection MIP, multiplanar reformation MPR, and volume-rendering on stenosis grading.
Fifty patients (33 men, 17 women) with symptomatic ICA stenosis were examined at 1.5T. Two imaging techniques and 3 postprocessing methods resulted in 6 image datasets per patient. Two readers independently evaluated ICA stenosis according to the North American Symptomatic Carotid Endarterectomy Trial criteria. Interobserver variability was calculated with the Pearson correlation coefficient and simultaneous confidence intervals (CI). The relationship of the values of ICA stenosis between the techniques was assessed by means of simultaneous 95% Tukey CI.
Interobserver agreement was high. Higher concordance was found for postprocessing techniques with TOF- than with CE-MRA; the mean difference between TOF-MPR and TOF-MIP was 0.4% (95% CI, -2.9%-3.8%). Stenosis values for CE-MPR differed significantly from those of CE volume-rendering (7.2%; 95% CI, 3.9%-10.6%).
Stenosis grading was found to be independent of the postprocessing technique except for comparison of CE-MPR with CE volume-rendering, with the volume-rendering technique resulting in higher stenosis values. MPR seems to be best-suited for measurement of ICA stenosis. Parameter setting is critical with volume-rendering, in which stenosis values were consistently higher compared with the other methods.
Probing the symmetry energy with heavy ions Lynch, W.G.; Tsang, M.B.; Zhang, Y. ...
Progress in particle and nuclear physics,
04/2009, Letnik:
62, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Constraints on the EoS for symmetric matter (equal neutron and proton numbers) at supra-saturation densities have been extracted from energetic collisions of heavy ions. Collisions of ...neutron-deficient and neutron-rich heavy ions now provide initial constraints on the EoS of neutron-rich matter at sub-saturation densities. Comparisons are made to other available constraints.
The mixed phase of quarks and hadrons which might exist in the dense matter encountered in the varying conditions of temperature and trapped neutrino fraction in proto-neutron stars is studied. We ...show that hadronic equations of state that maximize the quark content of matter at a given density generally minimize the extent of the mixed phase region in a neutron star of a given mass, and that only in extreme cases could a pure quark star result. Neutrino trapping inhibits the appearance of a mixed phase which leads to possible proto-neutron star metastability. We also demonstrate that the temperature along adiabats in the quark-hadron mixed phase is much smaller than what is found for the kaon condensate-hadron mixed phase. This could lead to core temperatures which are significantly lower in stars containing quarks than in those not containing quarks.
For the first time, a traditional radioactive nickel (63Ni) β emission ionization source for ion mobility spectrometry was employed with an atmospheric pressure ion mobility orthogonal reflector ...time-of-flight mass spectrometer (IM(tof)MS) to detect a chemical warfare agent (CWA) simulant from aerosol samples. Aerosol-phase sampling employed a quartz cyclonic chamber for sample introduction. The simulant reference material, which closely mimicked the characteristic chemical structure of CWAs as defined and described by Schedule 1, 2, or 3 of the Chemical Warfare Convention treaty verification, was used in this study. An overall elevation in arbitrary signal intensity of ∼1.0 orders of magnitude was obtained by the progressive increase of the thermal AP-IMS temperature from 75 to 275 °C. A mixture of one G-type nerve simulant (dimethyl methylphosphonate (DMMP)) in four (water, kerosene, gasoline, diesel) matrixes was found in each case (AP-IMS temperature 75−275 °C) to be clearly resolved in less than 2.20 × 104 μs using the IM(tof)MS instrument. Corresponding ions, masses, drift times, K o values, and arbitrary signal intensities for each of the sample matrixes are reported for the CWA simulant DMMP.
The detection of electron antineutrinos produced by natural radioactivity in the Earth could yield important geophysical information. The Kamioka liquid scintillator antineutrino detector (KamLAND) ...has the sensitivity to detect electron antineutrinos produced by the decay of 238U and 232Th within the Earth. Earth composition models suggest that the radiogenic power from these isotope decays is 16 TW, approximately half of the total measured heat dissipation rate from the Earth. Here we present results from a search for geoneutrinos with KamLAND. Assuming a Th/U mass concentration ratio of 3.9, the 90 per cent confidence interval for the total number of geoneutrinos detected is 4.5 to 54.2. This result is consistent with the central value of 19 predicted by geophysical models. Although our present data have limited statistical power, they nevertheless provide by direct means an upper limit (60 TW) for the radiogenic power of U and Th in the Earth, a quantity that is currently poorly constrained.
Apathy is the most common noncognitive symptom in Alzheimer's disease (AD). The structural correlates of apathy in AD have not yet been described.
We analyzed magnetic resonance imaging data of 35 AD ...patients with and without apathy.
There was a significant linear association between apathy severity and cortical gray matter atrophy in the bilateral anterior cingulate Brodmann area (BA) 24; r = 0.39-0.42, p = 0.01 and left medial frontal cortex (BA 8 and 9; r = 0.4, p < 0.02). Left mean cingulate cortical thinning predicted the presence/absence of apathy at the trend level of significance.
Our study demonstrates a strong association between apathy and the integrity of medial frontal regions in AD.
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