Purpose: To investigate the relationship between ADC values measured by diffusion-weighted MRI (DWI) and the split glomerular filtration rate (GFR).Materials and Methods: DWI (b ϭ 0 and 500 seconds/ mm 2 ) was performed with a 1.5T MR unit in 55 patients. The ADCs were calculated with ROIs positioned in the renal parenchyma, and the split GFRs were measured by 99 Tc m -DTPA scintigraphy using Gates' method. The 110 kidneys were divided into four groups: normal renal function (GFR 40 mL ⅐ minute -1 ), mild renal impairment (40 Ͼ GFR Ն 20 mL ⅐ minute -1 ), moderate renal impairment (20 Ͼ GFR Ն 10 mL ⅐ minute -1 ), and severe renal impairment (GFR Ͻ 10 mL ⅐ minute -1 ). The renal ADCs between four groups were statistically compared by analysis of variance (ANOVA), and the relationship between ADCs and GFR was examined using Pearson's correlation test.
Results:The mean renal ADCs of the four groups were 2.87 Ϯ 0.11, 2.55 Ϯ 0.17, 2.29 Ϯ 0.10, and 2.20 Ϯ 0.11 ϫ 10 -3 mm 2 /second, respectively. There was a statistically significant difference in renal ADCs among the four groups (P Ͻ 0.001). There was a positive correlation between the ADCs and split GFR (r ϭ 0.709).
Conclusion:The ADCs were significantly lower in impaired kidneys than in normal kidneys, and there was a positive correlation between the ADCs and GFR.
Solar magnetic flux ropes are core structures in driving solar activities. We construct a magnetic flux rope for a filament/prominence observed at 01:11 UT on 2011 June 21 in active region 11236 with a combination of state of the art methods, including triangulation from multi-perspective observations, the flux rope embedding method, the regularized Biot-Savart laws, and the magneto-frictional method. First, the path of the filament is reconstructed via the triangulation with 304Å images observed by the Atmospheric Imaging Assembly (AIA) on board Solar Dynamics Observatory (SDO ) and by the Extreme Ultraviolet Imager (EUVI) on board the twin Solar Terrestrial Relations Observatory (STEREO ). Then, a flux rope is constructed with the regularized Biot-Savart laws using the information of its axis. Next, it is embedded into a potential magnetic field computed from the photospheric radial magnetic field observed by the Helioseismic and Magnetic Imager on board SDO. The combined magnetic field is finally relaxed by the magneto-frictional method to reach a nonlinear force-free state. It is found that both models constructed by the regularized Biot-Savart laws and after the magneto-frictional relaxation coincide with the 304Å images. The distribution of magnetic dips coincides with part of the filament/prominence material, and the quasi-separatrix layers wrap the magnetic flux ropes and display hyperbolic flux tube structures. These models have the advantages to construct magnetic flux ropes in the higher atmosphere and weak magnetic field regions, which could be used as initial conditions for magnetohydrodynamic simulations of coronal mass ejections.
The propagation direction and true velocity of a solar coronal mass ejection, which are among the most decisive factors for its geo-effectiveness, are difficult to determine through single-perspective imaging observations. Here we show that Sun-as-a-star spectroscopic observations, together with imaging observations, could allow us to solve this problem. Using observations of the Extreme Ultraviolet Variability Experiment onboard the Solar Dynamics Observatory, we found clear blueshifted secondary emission components in extreme-ultraviolet spectral lines during a solar eruption on 2021 October 28. From simultaneous imaging observations, we found that the secondary components are caused by a mass ejection from the flare site. We estimated the line-of-sight (LOS) velocity of the ejecta from both the double Gaussian fitting method and the red-blue asymmetry analysis. The results of both methods agree well with each other, giving an average LOS velocity of the plasma of ∼423 km s−1. From the 304 Å image series taken by the Extreme ultraviolet Imager onboard the Solar Terrestrial Relation Observatory-A (STEREO-A) spacecraft, we estimated the plane-of-sky velocity from the STEREO-A viewpoint to be around 587 km s−1. The full velocity of the bulk motion of the ejecta was then computed by combining the imaging and spectroscopic observations, which turns out to be around 596 km s−1 with an angle of 42.°4 to the west of the Sun–Earth line and 16.°0 south to the ecliptic plane.
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