Laser Spectroscopy Measurements of Metastable Pionic Helium Atoms at Paul Scherrer Institute.

We review recent experiments carried out by the PiHe collaboration of the Paul Scherrer Institute (PSI) that observed an infrared transition of three-body pionic helium atoms by laser spectroscopy. These measurements may lead to a precise determination of the charged pion mass, and complement experiments of antiprotonic helium atoms carried out at the new ELENA facility of CERN.

Reaction Mechanism and Selectivity Control of Si Compound ALE Based on Plasma Modification and F-Radical Exposure.

In this work, atomic layer etching (ALE) of Si compounds using H2 or N2 plasma modification followed by fluorine radical exposure is discussed. It is shown that the H2 plasma modification process promotes the selective etching of SiN, SiC, and SiCO versus SiO2. The N2 plasma modification, on the other hand, enables the selective etching of SiC and SiCO versus SiN and SiO2. The origin of the etching selectivity between different Si compounds is investigated using a combination of in situ SE and FTIR supported by several ex situ analysis techniques. It is shown that the formation of a hydrogen-rich layer after plasma modification is essential to enable the ALE process. The hydrogen-rich layer can be formed due to ion and radicals of the modification plasma (H2 plasma modification) or be a result of the reconfiguration of hydrogen that is already present in the film (N2 plasma modification). The obtained insights are expected to further enhance the etching selectivity of Si compound ALE processes. Furthermore, it is anticipated that the process can be extended to many other compound materials such as Ti and Hf, as well as enable selective etching between their oxides, carbides, and nitrides.

Myelin and Axonal Damage in Normal-Appearing White Matter in Patients with Moyamoya Disease.

BACKGROUND AND PURPOSE: Although chronic ischemia is known to induce myelin and axonal damage in animal models, knowledge regarding patients with Moyamoya disease is limited. We aimed to investigate the presence of myelin and axonal damage in Moyamoya disease and their relationship with cognitive performance. MATERIALS AND METHODS: Eighteen patients with Moyamoya disease (16-55 years of age) and 18 age- and sex-matched healthy controls were evaluated with myelin-sensitive MR imaging based on magnetization transfer saturation imaging and 2-shell diffusion MR imaging. The myelin volume fraction, which reflects the amount of myelin sheath; the g-ratio, which represents the ratio of the inner (axon) to the outer (axon plus myelin) diameter of the fiber; and the axon volume fraction, which reflects axonal components, were calculated and compared between the patients and controls. In the patients with Moyamoya disease, the relationship between these parameters and cognitive task-measuring performance speed was also evaluated. RESULTS: Compared with the healthy controls, the patients with Moyamoya disease showed a significant decrease in the myelin and axon volume fractions (P < .05) in many WM regions, while the increases in the g-ratio values were not statistically significant. Correlations with cognitive performance were most frequently observed with the axon volume fraction (r = 0.52-0.54; P < .03 in the right middle and posterior cerebral artery areas) and were the strongest with the g-ratio values in the right posterior cerebral artery region (r = 0.64; P = .004). CONCLUSIONS: Myelin-sensitive MR imaging and diffusion MR imaging revealed that myelin and axonal damage exist in patients with Moyamoya disease. The relationship with cognitive performance might be stronger with axonal damage than with myelin damage.

Bayesian Estimation of CBF Measured by DSC-MRI in Patients with Moyamoya Disease: Comparison with 15O-Gas PET and Singular Value Decomposition.

BACKGROUND AND PURPOSE: CBF analysis of DSC perfusion using the singular value decomposition algorithm is not accurate in patients with Moyamoya disease. This study compared the Bayesian estimation of CBF against the criterion standard PET and singular value decomposition methods in patients with Moyamoya disease. MATERIALS AND METHODS: Nineteen patients with Moyamoya disease (10 women; 22-52 years of age) were evaluated with both DSC and 15O-gas PET within 60 days. DSC-CBF maps were created using Bayesian analysis and 3 singular value decomposition analyses (standard singular value decomposition, a block-circulant deconvolution method with a fixed noise cutoff, and a block-circulant deconvolution method that adopts an occillating noise cutoff for each voxel according to the strength of noise). Qualitative and quantitative analyses of the Bayesian-CBF and singular value decomposition-CBF methods were performed against 15O-gas PET and compared with each other. RESULTS: In qualitative assessments of DSC-CBF maps, Bayesian-CBF maps showed better visualization of decreased CBF on PET (sensitivity = 62.5%, specificity = 100%, positive predictive value = 100%, negative predictive value = 78.6%) than a block-circulant deconvolution method with a fixed noise cutoff and a block-circulant deconvolution method that adopts an oscillating noise cutoff for each voxel according to the strength of noise (P < .03 for all except for specificity). Quantitative analysis of CBF showed that the correlation between Bayesian-CBF and PET-CBF values (ρ = 0.46, P < .001) was similar among the 3 singular value decomposition methods, and Bayesian analysis overestimated true CBF (mean difference, 47.28 mL/min/100 g). However, the correlation between CBF values normalized to the cerebellum was better in Bayesian analysis (ρ = 0.56, P < .001) than in the 3 singular value decomposition methods (P < .02). CONCLUSIONS: Compared with previously reported singular value decomposition algorithms, Bayesian analysis of DSC perfusion enabled better qualitative and quantitative assessments of CBF in patients with Moyamoya disease.

White Matter Abnormalities in Multiple Sclerosis Evaluated by Quantitative Synthetic MRI, Diffusion Tensor Imaging, and Neurite Orientation Dispersion and Density Imaging.

BACKGROUND AND PURPOSE: A number of MR-derived quantitative metrics have been suggested to assess the pathophysiology of MS, but the reports about combined analyses of these metrics are scarce. Our aim was to assess the spatial distribution of parameters for white matter myelin and axon integrity in patients with relapsing-remitting MS by multiparametric MR imaging. MATERIALS AND METHODS: Twenty-four patients with relapsing-remitting MS and 24 age- and sex-matched controls were prospectively scanned by quantitative synthetic and 2-shell diffusion MR imaging. Synthetic MR imaging data were used to retrieve relaxometry parameters (R1 and R2 relaxation rates and proton density) and myelin volume fraction. Diffusion tensor metrics (fractional anisotropy and mean, axial, and radial diffusivity) and neurite orientation and dispersion index metrics (intracellular volume fraction, isotropic volume fraction, and orientation dispersion index) were retrieved from diffusion MR imaging data. These data were analyzed using Tract-Based Spatial Statistics. RESULTS: Patients with MS showed significantly lower fractional anisotropy and myelin volume fraction and higher isotropic volume fraction in widespread white matter areas. Areas with different isotropic volume fractions were included within areas with lower fractional anisotropy. Myelin volume fraction showed no significant difference in some areas with significantly decreased fractional anisotropy in MS, including in the genu of the corpus callosum and bilateral anterior corona radiata, whereas myelin volume fraction was significantly decreased in some areas where fractional anisotropy showed no significant difference, including the bilateral posterior limb of the internal capsule, external capsule, sagittal striatum, fornix, and uncinate fasciculus. CONCLUSIONS: We found differences in spatial distribution of abnormality in fractional anisotropy, isotropic volume fraction, and myelin volume fraction distribution in MS, which might be useful for characterizing white matter in patients with MS.

Preferences for health information in middle-aged Japanese workers based on health literacy levels: a descriptive study.

OBJECTIVES: To describe the health information preferences in middle-aged Japanese workers based on health literacy (HL) levels and presence of medications. STUDY DESIGN: A cross-sectional study. METHODS: We performed a web-based questionnaire survey with Japanese workers aged below 60 years. HL was assessed using the total score of communicative skills (five items) and critical skills (four items) from the 14-item Health Literacy Scale. Regarding their health information preferences, participants were asked about the health information they wanted (four items), could easily understand (six items), or easily use (two items) and answered on a 4-point scale (strongly agree/agree/disagree/strongly disagree). The percentages of the affirmative responses (strongly agree or agree) were compared among tertiles based on the HL score. RESULTS: We obtained data from a total of 3387 volunteers, of whom 510 participants were on either antihypertensive, lipid-lowering, or antidiabetic drugs. Compared with the high HL and middle HL groups, low HL had fewer affirmative responses to most health information items. Health information items received 70% of affirmative responses even in the low HL level. They were visually shown by figures or pictures, highlighted by colors for important points, could be read in 1-2 min, and were accessed on the Internet, regardless of the presence of medications. Additionally, the explanation for mechanisms of medications or lifestyle to prevent or improve diseases showed high affinity in all HL levels, only for those on medications. CONCLUSIONS: This result generates a hypothesis that low HL individuals have a low interest in health information. Our data showed several possible forms of health information with high affinity based on HL levels that would help plan future population approaches.

Neuromelanin or DaT-SPECT: which is the better marker for discriminating advanced Parkinson's disease?

BACKGROUND AND PURPOSE: Whether the neuromelanin-positive substantia nigra pars compacta area (NM-SNc) on neuromelanin magnetic resonance imaging (NM-MRI) and the specific binding ratio (SBR) on 123 I-N-v-fluoropropyl-2b-carbomethoxy3b-(4-iodophenyl)nortropane single photon emission computed tomography (DaT-SPECT) can be correlated with motor fluctuations (MFs) in advanced Parkinson's disease (PD) was investigated. METHODS: Thirty-five PD patients (60 ± 13 years) and 23 healthy individuals as controls (59 ± 19 years) were enrolled. The relationships between NM-MRI and DaT-SPECT were prospectively examined in two subgroups divided according to the presence or absence of MFs. Multivariate analysis was performed using the Cox proportional hazard model to screen for association factors. RESULTS: The NM-SNc size was correlated with the SBR (Spearman's ρ = 0.43, P < 0.05). The NM-SNc size was significantly reduced in PD with MFs compared with the subgroup without (P < 0.001), whereas the SBR did not significantly differ between the groups. NM-SNc size was a significant association factor for MFs (hazard ratio 0.94, P = 0.04). In receiver operating characteristic analysis of the factors for MF occurrence, the area under the receiver operating characteristic curve of the NM-SNc size showed a significant difference of 0.89 (P < 0.05) but no significant difference was found in the SBR. CONCLUSIONS: NM-SNc size was significantly correlated with the SBR in PD, but several factors in advanced PD were more closely associated with NM-SNc size than the SBR. NM-MRI might reflect the status of advanced PD more accurately than DaT-SPECT. Therefore, NM-MRI appears to provide a better marker for discriminating advanced PD than DaT-SPECT.

Improving the Quality of Synthetic FLAIR Images with Deep Learning Using a Conditional Generative Adversarial Network for Pixel-by-Pixel Image Translation.

BACKGROUND AND PURPOSE: Synthetic FLAIR images are of lower quality than conventional FLAIR images. Here, we aimed to improve the synthetic FLAIR image quality using deep learning with pixel-by-pixel translation through conditional generative adversarial network training. MATERIALS AND METHODS: Forty patients with MS were prospectively included and scanned (3T) to acquire synthetic MR imaging and conventional FLAIR images. Synthetic FLAIR images were created with the SyMRI software. Acquired data were divided into 30 training and 10 test datasets. A conditional generative adversarial network was trained to generate improved FLAIR images from raw synthetic MR imaging data using conventional FLAIR images as targets. The peak signal-to-noise ratio, normalized root mean square error, and the Dice index of MS lesion maps were calculated for synthetic and deep learning FLAIR images against conventional FLAIR images, respectively. Lesion conspicuity and the existence of artifacts were visually assessed. RESULTS: The peak signal-to-noise ratio and normalized root mean square error were significantly higher and lower, respectively, in generated-versus-synthetic FLAIR images in aggregate intracranial tissues and all tissue segments (all P < .001). The Dice index of lesion maps and visual lesion conspicuity were comparable between generated and synthetic FLAIR images (P = 1 and .59, respectively). Generated FLAIR images showed fewer granular artifacts (P = .003) and swelling artifacts (in all cases) than synthetic FLAIR images. CONCLUSIONS: Using deep learning, we improved the synthetic FLAIR image quality by generating FLAIR images that have contrast closer to that of conventional FLAIR images and fewer granular and swelling artifacts, while preserving the lesion contrast.

Effect of Gadolinium on the Estimation of Myelin and Brain Tissue Volumes Based on Quantitative Synthetic MRI.

BACKGROUND AND PURPOSE: The effect of gadolinium on the estimation of myelin has not been reported. The aim of the current study was to investigate the effects of gadolinium on automatic myelin and brain tissue volumetry via quantitative synthetic MR imaging. MATERIALS AND METHODS: The study included 36 patients who were referred for brain metastases screening, and quantitative synthetic MR imaging data before and after gadolinium-based contrast agent administration were analyzed retrospectively. Brain metastases were detected in 17 patients. WM volume, GM volume, CSF volume, non-WM/GM/CSF volume, myelin volume, brain parenchymal volume, myelin fraction (myelin volume/brain parenchymal volume), and intracranial volume were estimated. T1 and T2 relaxation times, proton density, and myelin partial volume per voxel averaged across the brain parenchyma were also analyzed. RESULTS: In patients with and without metastases after gadolinium-based contrast agent administration, measurements of WM and myelin volumes, and myelin fraction were significantly increased (+26.65 and +29.42 mL, +10.14 and +12.46 mL, +0.88% and +1.09%, respectively), whereas measurements of GM, CSF, brain parenchymal, and intracranial volumes were significantly decreased (-36.23 and -34.49 mL, -20.77 and -18.94 mL, -6.76 and -2.84 mL, -27.41 and -21.84 mL, respectively). Non-WM/GM/CSF volume did not show a significant change. T1, T2, and proton density were significantly decreased (-51.34 and -46.84 ms, -2.67 and -4.70 ms, -1.05%, and -1.28%, respectively) after gadolinium-based contrast agent administration, whereas measurements of myelin partial volume were significantly increased (+0.78% and +0.75%, respectively). CONCLUSIONS: Gadolinium had a significant effect on the automatic calculation of myelin and brain tissue volumes using quantitative synthetic MR imaging, which can be explained by decreases in T1, T2, and proton density.

Imaging Differences between Neuromyelitis Optica Spectrum Disorders and Multiple Sclerosis: A Multi-Institutional Study in Japan.

BACKGROUND AND PURPOSE: Both clinical and imaging criteria must be met to diagnose neuromyelitis optica spectrum disorders and multiple sclerosis. However, neuromyelitis optica spectrum disorders are often misdiagnosed as MS because of an overlap in MR imaging features. The purpose of this study was to confirm imaging differences between neuromyelitis optica spectrum disorders and MS with visually detailed quantitative analyses of large-sample data. MATERIALS AND METHODS: We retrospectively examined 89 consecutive patients with neuromyelitis optica spectrum disorders (median age, 51 years; range, 16-85 years; females, 77; aquaporin 4 immunoglobulin G-positive, 93%) and 89 with MS (median age, 36 years; range, 18-67 years; females, 68; relapsing-remitting MS, 89%; primary-progressive MS, 7%; secondary-progressive MS, 2%) from 9 institutions across Japan (April 2008 to December 2012). Two neuroradiologists visually evaluated the number, location, and size of all lesions using the Mann-Whitney U test or the Fisher exact test. RESULTS: We enrolled 79 patients with neuromyelitis optica spectrum disorders and 87 with MS for brain analysis, 57 with neuromyelitis optica spectrum disorders and 55 with MS for spinal cord analysis, and 42 with neuromyelitis optica spectrum disorders and 14 with MS for optic nerve analysis. We identified 911 brain lesions in neuromyelitis optica spectrum disorders, 1659 brain lesions in MS, 86 spinal cord lesions in neuromyelitis optica spectrum disorders, and 102 spinal cord lesions in MS. The frequencies of periventricular white matter and deep white matter lesions were 17% and 68% in neuromyelitis optica spectrum disorders versus 41% and 42% in MS, respectively (location of brain lesions, P < .001). We found a significant difference in the distribution of spinal cord lesions between these 2 diseases (P = .024): More thoracic lesions than cervical lesions were present in neuromyelitis optica spectrum disorders (cervical versus thoracic, 29% versus 71%), whereas they were equally distributed in MS (46% versus 54%). Furthermore, thoracic lesions were significantly longer than cervical lesions in neuromyelitis optica spectrum disorders (P = .001), but not in MS (P = .80). CONCLUSIONS: Visually detailed quantitative analyses confirmed imaging differences, especially in brain and spinal cord lesions, between neuromyelitis optica spectrum disorders and MS. These observations may have clinical implications.

Disruption of the pacemaker activity of interstitial cells of Cajal via nitric oxide contributes to postoperative ileus.

BACKGROUND: Interstitial cells of Cajal (ICC) serve as intestinal pacemakers. Postoperative ileus (POI) is a gastrointestinal motility disorder that occurs following abdominal surgery, which is caused by inflammation-induced dysfunction of smooth muscles and enteric neurons. However, the participation of ICC in POI is not well understood. In this study, we investigated the functional changes of ICC in a mouse model of POI. METHODS: Intestinal manipulation (IM) was performed to induce POI. At 24 h or 48 h after IM, the field potential of the intestinal tunica muscularis was investigated. Tissues were also examined by immunohistochemistry and electron microscopic analysis. KEY RESULTS: Gastrointestinal transit was significantly decreased with intestinal tunica muscularis inflammation at 24 h after IM, which was ameliorated at 48 h after IM. The generation and propagation of pacemaker potentials were disrupted at 24 h after IM and recovered to the control level at 48 h after IM. ICC networks, detected by c-Kit immunoreactivity, were remarkably disrupted at 24 h after IM. Electron microscopic analysis revealed abnormal vacuoles in the ICC cytoplasm. Interestingly, the ICC networks recovered at 48 h after IM. Administration of aminoguanidine, an inducible nitric oxide synthase inhibitor, suppressed the disruption of ICC networks. Ileal smooth muscle tissue cultured in the presence of nitric oxide donor, showed disrupted ICC networks. CONCLUSIONS AND INFERENCES: The generation and propagation of pacemaker potentials by ICC are disrupted via nitric oxide after IM, and this disruption may contribute to POI. When inflammation is ameliorated, ICC can recover their pacemaker function.

Automated brain tissue and myelin volumetry based on quantitative MR imaging with various in-plane resolutions.

BACKGROUND AND PURPOSE: Segmented brain tissue and myelin volumes can now be automatically calculated using dedicated software (SyMRI), which is based on quantification of R1 and R2 relaxation rates and proton density. The aim of this study was to determine the validity of SyMRI brain tissue and myelin volumetry using various in-plane resolutions. METHODS: We scanned 10 healthy subjects on a 1.5T MR scanner with in-plane resolutions of 0.8, 2.0 and 3.0mm. Two scans were performed for each resolution. The acquisition time was 7-min and 24-sec for 0.8mm, 3-min and 9-sec for 2.0mm and 1-min and 56-sec for 3.0mm resolutions. The volumes of white matter (WM), gray matter (GM), cerebrospinal fluid (CSF), non-WM/GM/CSF (NoN), brain parenchymal volume (BPV), intracranial volume (ICV) and myelin were compared between in-plane resolutions. Repeatability for each resolution was then analyzed. RESULTS: No significant differences in volumes measured were found between the different in-plane resolutions, except for NoN between 0.8mm and 2.0mm and between 2.0mm and 3.0mm. The repeatability error value for the WM, GM, CSF, NoN, BPV and myelin volumes relative to ICV was 0.97%, 1.01%, 0.65%, 0.86%, 1.06% and 0.25% in 0.8mm; 1.22%, 1.36%, 0.73%, 0.37%, 1.18% and 0.35% in 2.0mm and 1.18%, 1.02%, 0.96%, 0.45%, 1.36%, and 0.28% in 3.0mm resolutions. CONCLUSION: SyMRI brain tissue and myelin volumetry with low in-plane resolution and short acquisition times is robust and has a good repeatability so could be useful for follow-up studies.

Analysis of White Matter Damage in Patients with Multiple Sclerosis via a Novel In Vivo MR Method for Measuring Myelin, Axons, and G-Ratio.

BACKGROUND AND PURPOSE: Myelin and axon volume fractions can now be estimated via MR imaging in vivo, as can the g-ratio, which equals the ratio of the inner to the outer diameter of a nerve fiber. The purpose of this study was to evaluate WM damage in patients with MS via this novel MR imaging technique. MATERIALS AND METHODS: Twenty patients with relapsing-remitting MS with a combined total of 149 chronic plaques were analyzed. Myelin volume fraction was calculated based on simultaneous tissue relaxometry. Intracellular and CSF compartment volume fractions were quantified via neurite orientation dispersion and density imaging. Axon volume fraction and g-ratio were calculated by combining these measurements. Myelin and axon volume fractions and g-ratio were measured in plaques, periplaque WM, and normal-appearing WM. RESULTS: All metrics differed significantly across the 3 groups (P < .001, except P = .027 for g-ratio between periplaque WM and normal-appearing WM). Those in plaques differed most from those in normal-appearing WM. The percentage changes in plaque and periplaque WM metrics relative to normal-appearing WM were significantly larger in absolute value for myelin volume fraction than for axon volume fraction and g-ratio (P < .001, except P = .033 in periplaque WM relative to normal-appearing WM for comparison between myelin and axon volume fraction). CONCLUSIONS: In this in vivo MR imaging study, the myelin of WM was more damaged than axons in plaques and periplaque WM of patients with MS. Myelin and axon volume fractions and g-ratio may potentially be useful for evaluating WM damage in patients with MS.

First Elastic Electron Scattering from

The first elastic electron scattering has been successfully performed at the self-confining radioactive-isotope ion target (SCRIT) facility, the world's first electron scattering facility for SCRIT technique achieved high luminosity (over 10^{27} cm^{-2} s^{-1}, sufficient for determining the nuclear shape) with only 10^{8} target ions. While ^{132}Xe used in this time as a target is a stable isotope, the charge density distribution was first extracted from the momentum transfer distributions of the scattered electrons by comparing the results with those calculated by a phase shift calculation.

Zingiberis Siccatum Rhizoma, the active component of the Kampo formula Daikenchuto, induces anti-inflammatory actions through α7 nicotinic acetylcholine receptor activation.

BACKGROUND: We previously reported that Daikenchuto (DKT), a gastrointestinal prokinetic Japanese herbal (Kampo) medicine used for the treatment of postoperative ileus (POI), has characteristic potent anti-inflammatory activity. This effect may be partly mediated by the activation of α7 nicotinic acetylcholine receptor (nAChR). In this study, we identified the specific herbs in DKT that induce anti-inflammatory action. METHODS: The herbal components of DKT were individually administered orally to each mouse four times before and after intestinal manipulation (IM) was carried out on the distal ileum. The anti-inflammatory activity of each crude drug was subsequently evaluated using immunohistochemical analyses of relevant molecules. KEY RESULTS: Treatment with Zingiberis Siccatum Rhizoma (ZSR) but not the other components inhibited the infiltration of cluster of differentiation 68 (CD68)-positive macrophages as effectively as DKT treatment. Selective α7nAChR antagonists, such as methyllycaconitine citrate, or transient receptor potential ankyrin 1 (TRPA1) antagonists, such as HC-030031, significantly inhibited the amelioration of macrophage infiltration by ZSR. The inhibition of macrophage infiltration by ZSR was abolished in both α7nAChR and 5-hydroxytryptamine 4 receptor (5-HT4 R) knockout mice. CONCLUSIONS & INFERENCES: Daikenchuto-induced anti-inflammatory activity, which was mediated by inhibiting macrophage infiltration in POI, is dependent on the effects of ZSR. Zingiberis Siccatum Rhizoma activates TRPA1 channels possibly in enterochromaffin (EC) cells to release 5-HT, which stimulates 5-HT4 R in the myenteric plexus neurons to release ACh, which in turn activates α7nAChR on macrophages to inhibit inflammation in POI.

Blue light-induced immunosuppression in Bactrocera dorsalis adults, as a carryover effect of larval exposure.

Detrimental effects of ultraviolet (UV) light on living organisms are well understood, little is known about the effects of blue light irradiation. Although a recent study revealed that blue light caused more harmful effects on insects than UV light and blue light irradiation killed insect pests of various orders including Diptera, the effects of blue light on physiology of insects are still largely unknown. Here we studied the effects of blue light irradiation on cuticular melanin in larval and the immune response in adult stage of Bactrocera dorsalis. We also evaluated the effects of blue light exposure in larval stage on various age and mass at metamorphosis and the mediatory role of cuticular melanin in carryover effects of larval stressors across metamorphosis. We found that larvae exposed to blue light decreased melanin contents in their exoskeleton with smaller mass and delayed metamorphosis than insects reared without blue light exposure. Across metamorphosis, lower melanotic encapsulation response and higher susceptibility to Beauveria bassiana was detected in adults that had been exposed to blue light at their larval stage, thereby constituting the first evidence that blue light impaired adult immune function in B. dorsalis as a carryover effect of larval exposure.

Non-Contrast-Enhanced Silent Scan MR Angiography of Intracranial Anterior Circulation Aneurysms Treated with a Low-Profile Visualized Intraluminal Support Device.

BACKGROUND AND PURPOSE: The Low-Profile Visualized Intraluminal Support Device comprises a small-cell nitinol structure and a single-wire braided stent that provides greater metal coverage than previously reported intracranial stents, as well as assumed strong susceptibility artifacts. This study aimed to assess the benefits of non-contrast-enhanced MRA by using a Silent Scan (Silent MRA) for intracranial anterior circulation aneurysms treated with Low-Profile Visualized Intraluminal Support Device stents. MATERIALS AND METHODS: Thirty-one aneurysms treated with Low-Profile Visualized Intraluminal Support Device stents were assessed by using Silent MRA, 3D TOF-MRA, and x-ray DSA. The quality of MRA visualization of the reconstructed artery was graded on a 4-point scale from 1 (not visible) to 4 (excellent). Aneurysm occlusion status was evaluated by using a 2-grade scale (total occlusion/remnant [neck or aneurysm]). Weighted κ statistics were used to evaluate interobserver and intermodality agreement. RESULTS: The mean scores ± SDs for Silent MRA and 3D TOF-MRA were 3.16 ± 0.79 and 1.48 ± 0.67 (P < .05), respectively, with substantial interobserver agreement (κ = 0.66). The aneurysm occlusion rates of the 2-grade scale (total occlusion/remnant [neck or aneurysm]) were 69%/31% for DSA, 65%/35% for Silent MRA, and 92%/8% for 3D TOF-MRA, respectively. The intermodality agreements were 0.88 and 0.30 for DSA/Silent MRA and DSA/3D TOF-MRA, respectively. CONCLUSIONS: Silent MRA seems to be useful for visualizing intracranial anterior circulation aneurysms treated with Low-Profile Visualized Intraluminal Support Device stents.

Synthetic MRI in the Detection of Multiple Sclerosis Plaques.

BACKGROUND AND PURPOSE: Synthetic MR imaging enables the creation of various contrast-weighted images including double inversion recovery and phase-sensitive inversion recovery from a single MR imaging quantification scan. Here, we assessed whether synthetic MR imaging is suitable for detecting MS plaques. MATERIALS AND METHODS: Quantitative and conventional MR imaging data on 12 patients with MS were retrospectively analyzed. Synthetic T2-weighted, FLAIR, double inversion recovery, and phase-sensitive inversion recovery images were produced after quantification of T1 and T2 values and proton density. Double inversion recovery images were optimized for each patient by adjusting the TI. The number of visible plaques was determined by a radiologist for a set of these 4 types of synthetic MR images and a set of conventional T1-weighted inversion recovery, T2-weighted, and FLAIR images. Conventional 3D double inversion recovery and other available images were used as the criterion standard. The total acquisition time of synthetic MR imaging was 7 minutes 12 seconds and that of conventional MR imaging was 6 minutes 29 seconds The lesion-to-WM contrast and lesion-to-WM contrast-to-noise ratio were calculated and compared between synthetic and conventional double inversion recovery images. RESULTS: The total plaques detected by synthetic and conventional MR images were 157 and 139, respectively (P = .014). The lesion-to-WM contrast and contrast-to-noise ratio on synthetic double inversion recovery images were superior to those on conventional double inversion recovery images (P = .001 and < 0.001, respectively). CONCLUSIONS: Synthetic MR imaging enabled detection of more MS plaques than conventional MR imaging in a comparable acquisition time. The contrast for MS plaques on synthetic double inversion recovery images was better than on conventional double inversion recovery images.

Usefulness of Non-Contrast-Enhanced MR Angiography Using a Silent Scan for Follow-Up after Y-Configuration Stent-Assisted Coil Embolization for Basilar Tip Aneurysms.

BACKGROUND AND PURPOSE: Y-configuration stent-assisted coil embolization is used for treating wide-neck aneurysms. Noninvasive alternatives to x-ray DSA for follow-up after Y-configuration stent-assisted coil embolization treatment are required. This study aimed to assess the usefulness of non-contrast-enhanced MRA by using a Silent Scan (silent MRA) for follow-up after Y-configuration stent-assisted coil embolization for basilar tip aneurysms. MATERIALS AND METHODS: Seven patients treated with Y-configuration stent-assisted coil embolization for basilar tip aneurysms underwent silent MRA, 3D TOF-MRA, and DSA. Silent MRA and 3D TOF-MRA images were obtained during the same scan session on a 3T MR imaging system. Two neuroradiologists independently reviewed both types of MRA images and subjectively scored the flow in the stents on a scale of 1 (not visible) to 5 (nearly equal to DSA) by referring to the latest DSA image as a criterion standard. Furthermore, we evaluated the visualization of the neck remnant. RESULTS: In all patients, the 2 observers gave a higher score for the flow in the stents on silent MRA than on 3D TOF-MRA. The average score ± standard deviation was 4.07 ± 0.70 for silent MRA and 1.93 ± 0.80 (P < .05) for 3D TOF-MRA. Neck remnants were depicted by DSA in 5 patients. In silent MRA, neck remnants were depicted in 5 patients, and visualization was similar to DSA; however, in 3D TOF-MRA, neck remnants were depicted in only 1 patient. CONCLUSIONS: Silent MRA might be useful for follow-up after Y-configuration stent-assisted coil embolization.