We propose, analyze and demonstrate experimentally an entirely new optical effect in which the centroid of a coherent optical beam can be designed to propagate along a curved trajectory in free space ...by tailoring the spatial distribution of linear polarization across the transverse beam profile. Specifically, a non-zero spatial gradient of second order or higher in the linear state of polarization is shown to cause the beam centroid to “accelerate” in the direction transverse to the direction of propagation. The effect is confirmed experimentally using spatial light modulation to create the distribution in linear polarization and then measuring the transverse location of the beam profile at varying propagation distances. The observed displacement of the beam centroid is shown to closely match the theory out to 34m propagation distance.
•Compressed sensing made it possible to obtain single breath-hold 3D-MRCP (BH-MRCP).•Acquisition time of respiratory-gated 3D-MRCP (RG-MRCP) was 10 times of BH-MRCP.•Image quality of BH-MRCP was not ...significantly better than that of RG-MRCP.•Image quality of RG-MRCP was occasionally degraded by severe motion artifacts.•Combine use of RG-MRCP and BH-MRCP was useful to obtain stable and effective MRCP.
To clarify the clinical usefulness of breath-hold compressed sensing three-dimensional magnetic resonance cholangiopancreatography (BH-MRCP) added to conventional respiratory-gating MRCP (RG-MRCP), we prospectively evaluated the image quality of BH-MRCP and compared it with that of RG-MRCP. We also evaluated to what extent the overall image quality was improved by adding BH-MRCP to RG-MRCP.
A total of 113 patients who underwent RG-MRCP and BH-MRCP at a 3-T MR unit were enrolled. We set a scan time of approximately 180 s for RG-MRCP and 20 s for BH-MRCP before examination, and measured actual scan time and assessed image quality using a 5-point scale (5, good; 1, poor). Image quality scores of 1, 2 and 3 were considered clinically inadequate. Image quality scores of RG-MRCP and BH-MRCP were compared. In addition, we compared “RG-MRCP alone” and “hybrid MRCP” (the best-scoring image was picked from RG-MRCP and BH-MRCP when the RG-MRCP score was clinically inadequate).
The mean actual scan time of RG-MRCP/BH-MRCP was 191/20 s. The mean scores of RG-MRCP, BH-MRCP and hybrid MRCP were 3.67, 3.35 and 3.92, respectively. The score of hybrid MRCP was significantly better than that of RG-MRCP (P < 0.05). The image quality of RG-MRCP was clinically inadequate in 43/113 (38 %) cases and the inadequate image quality was improved to be clinically adequate in 13/43 (30 %) cases by adding BH-MRCP.
BH-MRCP brings added value to RG-MRCP because an additional examination of BH-MRCP could compensate for the image deterioration of RG-MRCP caused by motion artifacts.
Shedding light on a theme which affects Muslim-Christian conversation to the present day, this book describes the earliest extant interpretations of the Qur'ān's "tampering" verses which have been ...used to support the Muslim accusation of the corruption of pre-Qur'ānic scriptures.
Background
Changes in muscle fat composition as for example observed in sarcopenia or muscular dystrophy affect physical performance and muscular function, like strength and power. The purpose of the ...present study is to measure the repeatability of Dixon magnetic resonance imaging (MRI) for assessing muscle volume and fat in the thigh. Furthermore, repeatability of magnetic resonance spectroscopy (MRS) for assessing muscle fat is determined.
Methods
A prototype 6‐point Dixon MRI method was used to measure muscle volume and muscle proton density fat fraction (PDFF) in the left thigh. PDFF was measured in musculus semitendinosus of the left thigh with a T2‐corrected multi‐echo MRS method. For the determination of short‐term repeatability (consecutive examinations), the root mean square coefficients of variation of Dixon MRI and MRS data of 23 young and healthy (29 ± 5 years) and 24 elderly men with sarcopenia (78 ± 5 years) were calculated. For the estimation of the long‐term repeatability (13 weeks between examinations), the root mean square coefficients of variation of MRI data of seven young and healthy (31 ± 7 years) and 23 elderly sarcopenic men (76 ± 5 years) were calculated. Long‐term repeatability of MRS was not determined.
Results
Short‐term errors of Dixon MRI volume measurement were between 1.2% and 1.5%, between 2.1% and 1.6% for Dixon MRI PDFF measurement, and between 9.0% and 15.3% for MRS. Because of the high short‐term repeatability errors of MRS, long‐term errors were not determined. Long‐term errors of MRI volume measurement were between 1.9% and 4.0% and of Dixon MRI PDFF measurement between 2.1% and 4.2%.
Conclusions
The high degree of repeatability of volume and PDFF Dixon MRI supports its use to predict future mobility impairment and measures the success of therapeutic interventions, for example, in sarcopenia in aging populations and muscular dystrophy. Because of possible inhomogeneity of fat infiltration in muscle tissue, the application of MRS for PDFF measurements in muscle is more problematic because this may result in high repeatability errors. In addition, the tissue composition within the MRS voxel may not be representative for the whole muscle.
Basic research has been done on diffusion-welded joints with the overall aim of an adjusted interface design. The phase formation of aluminium alloy/magnesium alloy bonds has been revealed by X-ray ...diffraction, energy-dispersive spectroscopy and electron back-scatter diffraction. The presence of Al
12
Mg
17
and Al
3
Mg
2
phases in a bi-layer has been confirmed. The distribution and microstructure of the formed intermetallics and the arrangement of the precipitates originating from the alloys have been determined. Precipitates originating from the alloys agglomerate in the bi-layered welding zone. Their arrangement in combination with the grain boundary evolution of the intermetallics and the change of the aluminium base solid solution in the interface region has a significant influence on the mechanical properties of the joint.
To establish and evaluate an ultra-fast MRI screening protocol for prostate cancer (PCa) in comparison to the standard multiparametric (mp) protocol, reducing scan time and maintaining adequate ...diagnostic performance.
This prospective single-center study included consecutive biopsy-naïve patients with suspected PCa between December 2022 and March 2023. A PI-RADSv2.1 conform mpMRI protocol was acquired in a 3 T scanner (scan time: 25 min 45 sec). In addition, two deep-learning (DL) accelerated sequences (T2- and diffusion-weighted) were acquired, serving as a screening protocol (scan time: 3 min 28 sec). Two readers evaluated image quality and the probability of PCa regarding PI-RADSv2.1 scores in two sessions. The diagnostic performance of the screening protocol with mpMRI serving as the reference standard was derived. Inter- and intra-reader agreements were evaluated using weighted kappa statistics.
We included 77 patients with 97 lesions (mean age: 66 years; SD: 7.7). Diagnostic performance of the screening protocol was excellent with a sensitivity and specificity of 100%/100% and 89%/98% (cut-off ≥ PI-RADS 4) for reader 1 (R1) and reader 2 (R2), respectively. Mean image quality was 3.96 (R1) and 4.35 (R2) for the standard protocol vs. 4.74 and 4.57 for the screening protocol (p < 0.05). Inter-reader agreement was moderate (κ: 0.55) for the screening protocol and substantial (κ: 0.61) for the multiparametric protocol.
The ultra-fast screening protocol showed similar diagnostic performance and better imaging quality compared to the mpMRI in under 15% of scan time, improving efficacy and enabling the implementation of screening protocols in clinical routine.
The ultra-fast protocol enables examinations without contrast administration, drastically reducing scan time to 3.5 min with similar diagnostic performance and better imaging quality. This facilitates patient-friendly, efficient examinations and addresses the conflict of increasing demand for examinations at currently exhausted capacities.
Time-consuming MRI protocols are in conflict with an expected increase in examinations required for prostate cancer screening. An ultra-fast MRI protocol shows similar performance and better image quality compared to the standard protocol. Deep-learning acceleration facilitates efficient and patient-friendly examinations, thus improving prostate cancer screening capacity.
Purpose: The optimal temporal resolution for free-breathing dynamic contrast-enhanced MRI (FBDCE-MRI) of the pancreas has not been determined. This study aimed to evaluate the appropriate temporal ...resolution to achieve good image quality and to perform pharmacokinetic analysis in FBDCE-MRI of the pancreas using golden-angle radial sparse parallel (GRASP).Methods: Sixteen participants (53 ± 15 years, eight females) undergoing FBDCE-MRI were included in this prospective study. Images were retrospectively reconstructed at four temporal resolutions (1.8, 3.0, 4.8, and 7.8s). Two radiologists (5 years of experience) evaluated the image quality of each reconstructed image by assessing the visualization of the celiac artery (CEA), the common hepatic artery, the splenic artery, each area of the pancreas, and artifacts using a 5-point scale. Using Tissue-4D, pharmacokinetic parameters were calculated for each area in the reconstructed images at each temporal resolution for 16 examinations, excluding two with errors in the pharmacokinetic modeling analysis. Friedman and Bonferroni tests were used for analysis. A P value < 0.05 was considered statistically significant.Results: During vascular assessment, only scores for the CEA at 7.8s were significantly lower than the other temporal resolutions. Scores of all pancreatic regions and artifacts were significantly lower at 1.8s than at 4.8s and 7.8s. In the pharmacokinetic analysis, all volume transfer coefficients (Ktrans), rate constants (Kep), and the initial area under the concentration curve (iAUC) in the pancreatic head and tail were significantly lower at 4.8s and 7.8s than at 1.8s. iAUC in the pancreatic body and extracellular extravascular volume fraction (Ve) in the pancreatic head were significantly lower at 7.8s than at 1.8s.Conclusion: A temporal resolution of 3.0s is appropriate to achieve image quality and perform pharmacokinetic analysis in FBDCE-MRI of the pancreas using GRASP.
•MRC on T1-weighted images (T1-MRC) can be obtained with Gd-EOB-DTPA administration.•T1-MRC with either technique enables high-resolution MRC with 1-mm isovoxel.•There was no difference between the ...two kinds of T1-MRC in image quality.•High-resolution T1-MRC may produce higher-quality images than conventional T2-MRC.
To compare the quality of images obtained by T1-weighted hepatobiliary MR cholangiography using Gd-EOB-DTPA with 1-mm isovoxel acquisition and compressed sensing (T1-MRCCS) or parallel imaging (T1-MRCPI) for assessment of biliary tree anatomy.
We prospectively reviewed T1-MRCCS, T1-MRCPI, and respiratory-triggered 3D T2-weighted MR cholangiography (T2-MRC) images in 58 patients. Two radiologists independently assessed the three sets of images and scored the biliary tree visualization and overall image quality in all cases using a 5-point Likert scale. The resulting scores were compared among T1-MRCCS, T1-MRCPI, and T2-MRC images using a Friedman test followed by a Scheffe test. The inter-reader agreement in scoring was assessed using κ statistics.
The image quality scores for the gallbladder on both T1-MRCCS and T1-MRCPI were significantly lower than those on T2-MRC (p < 0.01) for both readers. Meanwhile, the image quality scores for the right and left hepatic ducts and the anterior and posterior branches of the right hepatic duct on both T1-MRCCS and T1-MRCPI were significantly higher than those on T2-MRC (p < 0.05) for both readers. For Reader 2, the overall image quality scores on T1-MRCCS and T1-MRCPI were both significantly higher than those on T2-MRC (p < 0.05). There were no significant differences between the image quality scores on T1-MRCCS and T1-MRCPI for visualization of each bile duct (p < 0.05).
There may be no significant difference in quality between T1-MRCCS images and T1-MRCPI images for assessment of biliary tree anatomy, and both types of images may be better than T2-MRC images, although clinical indication is limited compared with T2-MRC.
In actual or future fusion machines like ITER, JT-60SA, W7-X or the present EU-DEMO design, low temperature superconductor (LTS) cables are used or planned to be used in the magnet system to create ...the strong magnetic field necessary for plasma confinement. High temperature superconductors (HTS) offer the potential to increase the magnetic field strength in fusion magnet systems even further, allowing to build more compact fusion machines or to realize higher flux swings in central solenoids. In this work, two HTS conductors were fabricated and characterized by high current testing at 77 K in self-field conditions and at 4.2 K with an external magnetic field up to 12 T. Both samples offer the same amount of superconducting HTS tapes but differ in the assembly process and termination type. These tests were intended to validate the current KIT design of a HTS CroCo triplet conductor and to qualify a low degradation cable manufacturing process.
PDF
