Advantages of fluid and white matter suppression (FLAWS) with MP2RAGE compared with double inversion recovery turbo spin echo (DIR-TSE) at 7T.

Cerebrospinal fluid (CSF) and white matter (WM) signal suppression techniques allow better visualization of both WM and gray matter (GM) lesions in such disorders as multiple sclerosis and epilepsy. Recently, a technique, FLuid And White matter Suppression "FLAWS", has been proposed at 3 T based on the magnetization-prepared with two rapid gradient echoes (MP2RAGE) sequence. In this study, the FLAWS-MP2RAGE pulse sequence was compared with a double inversion recovery turbo spin echo (DIR-TSE) sequence at 7 T. Twenty-two healthy volunteers were examined. Isotropic spatial resolution of 1 mm and a scan time of approximately 6 min were chosen due to a restricted clinical schedule. Homogeneity of CSF and WM signal suppression was compared with GM signal as an intensity reference. Volumes of GM visualization and specific absorption rates (SARs) were compared using Wilcoxon-rank sum tests with Bonferroni-Holm correction for multiple comparisons. WM-to-GM signal ratios in FLAWS-MP2RAGE images were significantly lower than DIR-TSE (median: 24.5% vs 59.0%, P <  0.0001), whereas CSF-to-GM signal ratios in FLAWS-MP2RAGE were significantly higher than DIR-TSE (57.1% vs 38.3%, P =  0.0001). Ranges of the signal ratios between 20 and 80 percentiles were lower in FLAWS-MP2RAGE than DIR-TSE for WM (24.1% vs 37.2%, P <  0.0001) but were higher in FLAWS-MP2RAGE compared with DIR-TSE for CSF (80.8% vs 63.0%, P =  0.0001). Pixels of low GM signal (< 20% of the median) were mainly distributed at the skull base, and these low signal GM volume ratios were lower in FLAWS-MP2RAGE than DIR-TSE (2.27% vs 6.18%, P <  0.0001). Median SAR in sixteen subjects was 2.5 times higher in DIR-TSE than in FLAWS-MP2RAGE. FLAWS-MP2RAGE showed superior and more homogenous WM signal suppression, better GM visualization at the skull base and lower SAR compared with DIR-TSE, suggesting superiority of FLAWS-MP2RAGE at 7 T

Influence of Zr substitution on the stabilization of ThMn12-type (Nd1−αZrα)(Fe0.75Co0.25)11.25Ti0.75N1.2−1.4 (α = 0–0.3) compounds

The influence of Zr substitution in ThMn12 compounds was investigated using strip casting alloys. It was found that Zr substitution stabilized (Nd1−αZrα)(Fe0.75Co0.25)11.25Ti0.75N1.2−1.4 (α = 0–0.3) compounds. Specifically, a reduction in the lattice constant along the a-axis was observed. Energy-dispersive X-ray spectroscopy mapping combined with Cs-corrected scanning transmission electron microscopy indicated that Zr atoms preferentially occupied Nd 2a sites. Both the magnetic anisotropy field and saturation polarization were maximum at Zr substitution ratio α = 0.1. The (Nd1−αZrα)(Fe0.75Co0.25)11.25Ti0.75N1.2−1.4 (α = 0–0.3) compounds displayed higher saturation polarization than Nd2Fe14B at high temperatures

A (Nd, Zr)(Fe, Co)11.5Ti0.5Nx compound as a permanent magnet material

We studied NdFe11TiNx compounds as permanent magnet materials. The (Nd0.7,Zr0.3)(Fe0.75Co0.25)11.5Ti0.5N0.52 powder that contained a limited amount of the α-(Fe, Co) phase shows fairly good magnetic properties, such as a saturation polarization (Js) of 1.68 T and an anisotropic field (Ha) of 2.88 (Law of approach to saturation) – 4.0 MA/m (Intersection of magnetization curves). Both properties are comparable to those of the Nd2Fe14B phase

Towards HCP-Style macaque connectomes: 24-Channel 3T multi-array coil, MRI sequences and preprocessing

Macaque monkeys are an important animal model where invasive investigations can lead to a better understanding of the cortical organization of primates including humans. However, the tools and methods for noninvasive image acquisition (e.g. MRI RF coils and pulse sequence protocols) and image data preprocessing have lagged behind those developed for humans. To resolve the structural and functional characteristics of the smaller macaque brain, high spatial, temporal, and angular resolutions combined with high signal-to-noise ratio are required to ensure good image quality. To address these challenges, we developed a macaque 24-channel receive coil for 3-T MRI with parallel imaging capabilities. This coil enables adaptation of the Human Connectome Project (HCP) image acquisition protocols to the in-vivo macaque brain. In addition, we adapted HCP preprocessing methods to the macaque brain, including spatial minimal preprocessing of structural, functional MRI (fMRI), and diffusion MRI (dMRI). The coil provides the necessary high signal-to-noise ratio and high efficiency in data acquisition, allowing four- and five-fold accelerations for dMRI and fMRI. Automated FreeSurfer segmentation of cortex, reconstruction of cortical surface, removal of artefacts and nuisance signals in fMRI, and distortion correction of dMRI all performed well, and the overall quality of basic neurobiological measures was comparable with those for the HCP. Analyses of functional connectivity in fMRI revealed high sensitivity as compared with those from publicly shared datasets. Tractography-based connectivity estimates correlated with tracer connectivity similarly to that achieved using ex-vivo dMRI. The resulting HCP-style in vivo macaque MRI data show considerable promise for analyzing cortical architecture and functional and structural connectivity using advanced methods that have previously only been available in studies of the human brain