Three-dimensional Spin Research Articles

Magnetic field induced deformation of the spin density wave microphases in Ca3Co2O6

The frustrated triangular Ising magnet Ca$_3$Co$_2$O$_6$ has long been known for an intriguing combination of extremely slow spin dynamics and peculiar magnetic orders, such as the evenly-spaced non-equilibrium metamagnetic magnetization steps and the long-wavelength spin density wave (SDW) order, the latter of which is essentially an emergent crystal of solitons. Recently, an elaborate field-cooling protocol to bypass the low-field SDW phase was proposed to overcome the extraordinarily long timescale of spin relaxation that impeded previous experimental studies in equilibrium, which may point to a deep connection between the low-temperature slow relaxation and the cooling process passing through the low-field SDW phase. As the first step to elucidate the conjectured connection, we investigate the magnetic field-induced deformation of the SDW state and incommensurate-commensurate transitions, thereby mapping out the equilibrium in-field phase diagram for a realistic three-dimensional lattice spin model by using Monte Carlo simulations. We also discuss Ginzburg-Landau theory that includes several Umklapp terms as well as an effective sine-Gordon model, which can qualitatively explain the observed magnetic field-induced deformation of the SDW microphases.

Association of Cerebral Hemodynamics and Cognitive Function in Adult Patients with Moyamoya Disease: A Three-Dimensional Pseudo-Continuous Arterial Spin Labeling Study

Cognitive dysfunction is a serious complication of moyamoya disease (MMD) in adults, and reduced cerebral blood flow (CBF) might be the potential cause. We aimed to explore the correlation between cerebral hemodynamics and cognitive function in adults with MMD by using three-dimensional pseudo-continuous arterial spin labeling (3D-pCASL). A total of 24 MMD patients with a history of cerebral infarction, 25 asymptomatic MMD patients, and 25 healthy controls were prospectively enrolled in this study. All participants were performed 3D-pCASL, and cognitive function was evaluated with the Mini-Mental State Examination (MMSE), the Montreal Cognitive Assessment Scale (MoCA), and the Trail Making Test Part A (TMTA). The correlation between cerebral hemodynamics and cognitive function was explored in the region of interest-based analysis. Compared with healthy controls, both CBF and cognition decreased in adult MMD. In the infarction group, the MMSE and MoCA scores correlated with CBF of the right anterior cerebral artery (P=0.037 and 0.010, respectively) and the left middle cerebral artery (MCA) cortical territories (P=0.002 and 0.001, respectively), and the TMTA time-consuming has a negative correlation with CBF of the right and left MCA cortical territories (P=0.044 and 0.010, respectively); in the asymptomatic group, the MMSE and MoCA scores correlated with CBF of the left MCA cortical territory (P=0.032 and 0.029, respectively). The 3D-pCASL can find the hypoperfusion area of CBF in adults with MMD, and hypoperfusion in specific brain regions may cause cognitive dysfunction even in asymptomatic patients.

Comparison of single-postlabeling delay and seven-delay three-dimensional pseudo-continuous arterial spin labeling in the assessment of intracranial atherosclerotic disease.

The assessment of cerebral blood flow (CBF) is crucial in the evaluation of intracranial atherosclerotic disease. This study was performed to compare single postlabeling delay (PLD) 3-dimensional pseudo-continuous arterial spin labeling (3D-pCASL) and 7-delay 3D-pCASL magnetic resonance imaging in patients with intracranial atherosclerotic stenosis. A total of 26 patients with moderate to severe atherosclerotic stenosis or occlusion of an intracranial artery were prospectively enrolled in the study. Perfusion parameters were obtained in various regions of interest (ROIs), namely CBF for single PLDs of 1,525 ms (CBF1525 ms), 2,025 ms (CBF2025 ms), and 2,525 ms (CBF2525 ms) with 3D-pCASL, as well as arterial transit time (ATT) and transit-corrected CBF (CBFtransit-corrected) for 7-delay 3D-pCASL. The consistency of the perfusion parameters between single-PLD 3D-pCASL and 7-delay 3D-pCASL was investigated, and the relationship between vascular stenosis and perfusion parameters was explored. Bland-Altman plots compared the CBF values derived from single-PLD 3D-pCASL to those from CBFtransit-corrected. ATT significantly correlated with the difference between CBFtransit-corrected and CBF1525 ms, CBF2025 ms, and CBF2525 ms, respectively (P<0.05). Binary logistic regression analysis revealed that the CBFtransit-corrected and ATT correlated with the presence of moderate or more severe stenotic vascular territories (P<0.05). The single-PLD 3D-pCASL and the 7-delay 3D-pCASL showed inconsistencies in the assessment of CBF, and the perfusion parameters generated under the standard single-PLD 3D-pCASL were more affected by ATT. Moreover, CBFtransit-corrected and ATT were consistent with stenotic vascular territories, which is useful in the evaluation of intracranial atherosclerotic disease.

Modulation transfer function measurement of three-dimensional T1-weighted turbo spin echo sequence with low refocusing flip angles using single-plate method

This study aimed to demonstrate the usefulness of modulation transfer function (MTF) measurements using the single-plate method to evaluate changes in resolution properties that are dependent on three parameters: echo train length (ETL), low refocusing flip angle (RFA), and start-up echo in three-dimensional T1-weighted turbo spin echoes (TSE) with a low RFA and to optimize these parameters. Although the MTFs were slightly degraded with an RFA of 120°, they were considerably degraded with an RFA of ≤ 90°. On the other hand, the MTF of low RFA was greatly improved by setting the start-up echo, allowing setting a long ETL. The single-plate method provided a clear and easy evaluation of the resolution properties of low RFA TSE. Furthermore, this method allows us to visualize changes in the signal intensity of each echo in k-space, depending on the sequence variation. These results suggest that the MTF measurement using the single-plate method is useful for evaluating the resolution properties of TSE sequences and optimizing the measured parameters.

Quantitative association of cerebral blood flow, relaxation times and proton density in young and middle-aged primary insomnia patients: A prospective study using three-dimensional arterial spin labeling and synthetic magnetic resonance imaging.

To quantitatively measure the T1 value, T2 value, proton density (PD) value, and cerebral blood flow (CBF) in young and middle-aged primary insomnia (PI) patients, and analyze the correlations between relaxation times, PD, and CBF to explore potential brain changes. Cranial magnetic resonance (MR) images of 44 PI patients and 30 healthy subjects were prospectively collected for analysis. The T1, T2, PD, and CBF values of the frontal lobe, parietal lobe, temporal lobe, and occipital lobe were independently measured using three-dimensional arterial spin labeling (3D-ASL), synthetic magnetic resonance imaging (syMRI) and a whole-brain automatic segmentation method. The differences of these imaging indices were compared between PI patients and healthy subjects. Follow-up MR images were obtained from PI patients after 6 months to compare with pre-treatment images. The Wilcoxon signed rank test and Spearman rank were used for statistical analysis. Bilateral CBF asymmetry was observed in 38 patients, with significant differences in both the T2 value and CBF between the four lobes of the brain (p < 0.01). However, no significant difference was found in the T1 and PD values between the bilateral lobes. A negative correlation was found between CBF and T2 values in the right four lobes of patients with primary insomnia (PI). During follow-up examinations, five PI patients showed a disappearance of insomnia symptoms and a decrease in CBF in both brain lobes. Insomnia symptoms may be associated with high CBF, and most PI patients have higher CBF and lower T2 values in the right cerebral hemispheres. The right hemisphere appears to play a critical role in the pathophysiology of PI. The 3D-ASL and syMRI technologies can provide a quantitative imaging basis for investigating the brain conditions and changes in young and middle-aged PI patients.

Three-dimensional pseudo-continuous arterial spin labeling for evaluation of cerebral hemodynamic changes after revascularization in adult patients with moyamoya disease

To evaluate cerebral hemodynamic changes using three-dimensional pseudo-continuous arterial spin labeling (3D-pCASL) and its association with the changes of neurological symptoms in adult patients with moyamoya disease after revascularization. We prospectively collected the clinical and radiographic data of 40 adult patients with moyamoya disease diagnosed by digital subtraction angiography (DSA) or magnetic resonance angiography (MRA) undergoing unilateral superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis. All the patients underwent 3D-pCASL examination before and after the surgery, and were followed up for 3 to 11 months after the operation. The region of interest (ROI) was located in the middle cerebral artery cortical territory covering the surgical side and ipsilateral cerebellar hemisphere. Cerebral blood flow (CBF) and relative CBF (rCBF) values were compared before and after the surgery, and the changes in cerebral hemodynamics were evaluated. The correlations were analyzed between preoperative rCBF and Suzuki stage and between the changes in postoperative neurological symptoms and rCBF. The mean CBF of the patients increased significantly from 53.96±10.04 mL·100 g-1·min-1 to 58.90±13.57 mL·100 g-1·min-1 after the operation (t=-3.068, P=0.004); the mean rCBF also increased significantly after the operation (0.96 ± 0.14 vs 1.15 ± 0.18; t=-7.155, P < 0.001). The changes in postoperative neurological symptoms were significantly correlated with the changes in rCBF (P=0.017) and the type of disease onset (P < 0.001). 3D-pCASL is an valuable means for noninvasive monitoring of hemodynamic changes after revascularization in adult patients with moyamoya disease without the use of contrast agent.

Carotid Artery Thrombus in Antiphospholipid Antibody Syndrome.

HomeRadiologyRecently Published PreviousNext Reviews and CommentaryFree AccessImages in RadiologyCarotid Artery Thrombus in Antiphospholipid Antibody SyndromeZongli Han, Hui Qi Zongli Han, Hui Qi Author AffiliationsFrom the Department of Neurosurgery, Peking University Shenzhen Hospital, 1120 Lianhua Rd, Shenzhen 518036, PR China.Address correspondence to H.Q. (email: [email protected]).Zongli HanHui Qi Published Online:Mar 14 2023https://doi.org/10.1148/radiol.221836MoreSectionsPDF ToolsImage ViewerAdd to favoritesCiteTrack CitationsPermissionsReprints ShareShare onFacebookTwitterLinked In A 23-year-old previously healthy woman presented with sudden-onset right-sided hemiparesis and paresthesia. Brain MRI scan demonstrated acute left frontal lobe embolic infarcts. High-spatial-resolution vessel wall MRI scan revealed an isointense peripherally enhancing lesion in the left common carotid artery with resultant severe luminal narrowing, compatible with an intraluminal thrombus (Figure, A–C). Contrast-enhanced US image confirmed free-floating thrombus with proximal attachment to the vessel wall (Figure, D). Endarterectomy was performed, and an organized thrombus was confirmed with pathologic process. Antibody serology tests were positive for anticardiolipin immunoglobulin G, β-2 glycoprotein immunoglobulin G, and lupus anticoagulants. The diagnosis of antiphospholipid antibody syndrome was established according to the Miyakis criteria (1,2). The patient was treated with warfarin and showed no signs of clinical or radiologic relapse at 1-year follow-up.Images in a 23-year-old woman with sudden-onset right-sided hemiparesis and paresthesia. (A–C) T1-weighted three-dimensional isotropic variable flip-angle fast spin echo MRI scans with black-blood technique with a 3-T clinical scanner (uMR 780; United Imaging Healthcare) show vessel walls. (A) Axial and (B) coronal T1-weighted images without contrast material show an intraluminal T1 isointense lesion within the left common carotid artery with resultant severe luminal narrowing (arrows). (C) Coronal contrast-enhanced T1-weighted image shows peripheral linear contrast enhancement of the thrombus (arrow). (D) Contrast-enhanced US image demonstrates a free-floating thrombus with microbubbles between the thrombus and the carotid vessel (*) with proximal attachment to the vessel wall (arrowhead).Download as PowerPointOpen in Image Viewer Antiphospholipid antibody syndrome is an autoimmune disease characterized by recurrent arterial or venous thrombosis, pathologic pregnancy, and positive antiphospholipid antibodies (3). Neurologic manifestations, especially cerebral ischemia, are frequently present; however, presentation with carotid thrombus is uncommon (4).Disclosures of conflicts of interest: Z.H. No relevant relationships. H.Q. No relevant relationships.AcknowledgmentsThe authors thank Hui Zhang from the Department of Radiology, who helped with the interpretation of the high-resolution MRI. They also thank Liya Wei from the Department of Ultrasound, who helped with the interpretation of the contrast-enhanced US image.

Response to "Comment on 'Spin- and angle-resolved inverse photoemission setup with spin orientation independent from electron incidence angle'" [Rev. Sci. Instrum. 93, 093904 (2022)

We reply to the Comment by Donath et al. on our setup, which allows a total 3D control of the polarization direction of the electron beam in an inverse photoemission spectroscopy (IPES) experiment, a significant advance with respect to previous setups with partial polarization control. Donath et al. claim an incorrect operation of our setup after comparing their results, treated to enhance the spin asymmetry, with our spectra without the same treatment. They also equal spectra backgrounds instead of equaling peak intensities above the background. Thus, we compare our Cu(001) and Au(111) results with the literature. We reproduce previous results, including spin-up/spin-down spectral differences observed for Au and not observed for Cu. Also, spin-up/spin-down spectral differences appear at the expected reciprocal space regions. In the Comment, it is also stated that our tuning of the spin polarization misses the target because the spectra background changes when tuning the spin. We argue that the background change is irrelevant to IPES since the information is contained in peaks produced by primary electrons, those having conserved their energy in the inverse photoemission process. Second, our experiments agree with previous results from Donath et al. [Wissing et al., New J. Phys. 15, 105001 (2013)] and with a zero-order quantum-mechanical model of spins in vacuum. Deviations are explained by more realistic descriptions including the spin transmission through an interface. Consequently, the operation of our original setup is fully demonstrated. Our development corresponds to "the promising and rewarding angle-resolved IPES setup with the three-dimensional spin resolution," as indicated in the Comment, after our work.

Observation of phononic skyrmions based on hybrid spin of elastic waves

Skyrmions with topologically stable configuration have shown a promising route toward high-density magnetic and photonic information processing due to their defect-immune and low-driven energy. Here, we experimentally report and observe the existence of phononic skyrmions as new topological structures formed by the three-dimensional hybrid spin of elastic waves. We demonstrate that the frequency-independent spin configuration leads to ultra-broadband feature of phononic skyrmions, which can be produced in any solid structure, including chip-scale ones. We further experimentally show the excellent robustness of the flexibly movable phononic skyrmion lattices against local defects of disorder, sharp corners, and even rectangular holes. Our research opens a vibrant horizon toward an unprecedented way for elastic wave manipulation and structuration by spin configuration and offers a promising lever for alternative phononic technologies, including information processing, biomedical testing, and wave engineering.

Topology of three-dimensional Dirac semimetals and quantum spin Hall systems without gapless edge modes

A theoretical framework is outlined for calculating the spin-Chern number of topological Dirac semimetals and quantum spin Hall insulators lacking spin-conservation law and gapless edge modes. Spin-charge separation and quantized spin-pumping are probed by inserting a magnetic flux tube.

Ground States of Heisenberg Spin Clusters from a Cluster-Based Projected Hartree–Fock Approach

Recent work on approximating ground states of Heisenberg spin clusters by projected Hartree–Fock theory (PHF) is extended to a cluster-based ansatz (cPHF). Whereas PHF variationally optimizes a site–spin product state for the restoration of spin- and point-group symmetry, cPHF groups sites into discrete clusters and uses a cluster-product state as the broken-symmetry reference. Intracluster correlation is thus already included at the mean-field level, and intercluster correlation is introduced through symmetry projection. Variants of cPHF differing in the broken and restored symmetries are evaluated for ground states and singlet-triplet gaps of antiferromagnetic spin rings for various cluster sizes, where cPHF in general affords a significant improvement over ordinary PHF, although the division into clusters lowers the cyclical symmetry. In contrast, certain two- or three-dimensional spin arrangements permit cluster groupings compatible with the full spatial symmetry. We accordingly demonstrate that cPHF yields approximate ground states with correct spin- and point-group quantum numbers for honeycomb lattice fragments and symmetric polyhedra.

Noninvasively evaluating the grade and IDH mutation status of gliomas by using mono-exponential, bi-exponential diffusion-weighted imaging and three-dimensional pseudo-continuous arterial spin labeling

ObjectivesTo noninvasively assess the diagnostic performance of diffusion-weighted imaging (DWI), bi-exponential intravoxel incoherent motion imaging (IVIM) and three-dimensional pseudo-continuous arterial spin labeling (3D pCASL) in differentiating lower-grade gliomas (LGGs) from high-grade gliomas (HGGs), and predicting the isocitrate dehydrogenase (IDH) mutation status. Materials and methodsNinety-five patients with pathologically confirmed grade 2–4 gliomas with preoperative DWI, IVIM and 3D pCASL were enrolled in this study. The Student’s t test and Mann-Whitney U test were used to evaluate differences in parameters of DWI, IVIM and 3D pCASL between LGG and HGG as well as between mutant and wild-type IDH in grade 2 and 3 diffusion astrocytoma; receiver operator characteristic (ROC) analysis was used to assess the diagnostic performance. ResultsThe value of ADCmean, ADCmin, Dmean and Dmin in HGGs were lower than in LGGs, while the value of CBFmean and CBFmax in HGGs were higher than in LGGs. In ROC analysis, the AUC values of Dmean, Dmin and CBFmax were 0.827, 0.878 and 0.839, respectively. The combination of CBFmax and Dmin displayed the highest diagnostic performance to distinguish LGGs from HGGs, with AUC 0.906, sensitivity 82.4 %, and specificity 86.4 %. In grades 2 and 3 diffusion astrocytoma patients, ADCmin, Dmean, Dmin, CBFmean and CBFmax showed significant differences between IDHmut and IDHwt group (p < 0.05, 0.001, 0.001, 0.01 and 0.001, respectively) and the AUC values were 0. 709, 0.849, 0.919, 0.755 and 0.873, respectively. Similarly, the combination of CBFmax and Dmin demonstrated the highest AUC value (0.938) in prediction IDH mutation status, with sensitivity 92.9 %, and specificity 95.5 %. ConclusionThe combination of IVIM and 3D pCASL can be used in prediction histologic grade and IDH mutation status of glioma noninvasively.

Three-dimensional topological magnetic monopoles and their interactions in a ferromagnetic meta-lattice.

Topological magnetic monopoles (TMMs), also known as hedgehogs or Bloch points, are three-dimensional (3D) non-local spin textures that are robust to thermal and quantum fluctuations due to the topology protection1-4. Although TMMs have been observed in skyrmion lattices1,5, spinor Bose-Einstein condensates6,7, chiral magnets8, vortex rings2,9 and vortex cores10, it has been difficult to directly measure the 3D magnetization vector field of TMMs and probe their interactions at the nanoscale. Here we report the creation of 138 stable TMMs at the specific sites of a ferromagnetic meta-lattice at room temperature. We further develop soft X-ray vector ptycho-tomography to determine the magnetization vector and emergent magnetic field of the TMMs with a 3D spatial resolution of 10 nm. This spatial resolution is comparable to the magnetic exchange length of transition metals11, enabling us to probe monopole-monopole interactions. We find that the TMM and anti-TMM pairs are separated by 18.3 ± 1.6 nm, while the TMM and TMM, and anti-TMM and anti-TMM pairs are stabilized at comparatively longer distances of 36.1 ± 2.4 nm and 43.1 ± 2.0 nm, respectively. We also observe virtual TMMs created by magnetic voids in the meta-lattice. This work demonstrates that ferromagnetic meta-lattices could be used as a platform to create and investigate the interactions and dynamics of TMMs. Furthermore, we expect that soft X-ray vector ptycho-tomography can be broadly applied to quantitatively image 3D vector fields in magnetic and anisotropic materials at the nanoscale.

Self-consistent computation of spin torques and magneto-resistance in tunnel junctions and magnetic read-heads with metallic pinhole defects

A three-dimensional self-consistent spin transport model is developed, which includes both tunnelling transport, leading to tunnelling magneto-resistance, as well as metallic transport, leading to giant magneto-resistance. An explicit solution to the drift-diffusion model is also derived, which allows analysing the effect of both the reference and free layer thickness on the spin-transfer torque polarization and field-like coefficient. It is shown the model developed here can be used to compute the signal-to-noise ratio in realistic magnetic read-heads, where spin torque-induced fluctuations and instabilities limit the maximum operating voltage. The effect of metallic pinhole defects in the insulator layer is also analysed. Increasing the area covered by pinholes results in a rapid degradation of the magneto-resistance, following an inverse dependence. Moreover, the spin torque angular dependence becomes skewed, similar to that obtained in fully metallic spin valves, and the spin-transfer torque polarization decreases. The same results are obtained when considering tunnel junctions with a single pinhole defect, but decreasing cross-sectional area, showing that even a single pinhole defect can significantly degrade the performance of tunnel junctions and magnetic read-heads below the 40 nm node.

Three-dimensional pseudocontinuous arterial spin labeling perfusion imaging shows cerebral blood flow perfusion decline in attention-deficit/hyperactivity disorder children.

To investigate the feasibility of three-dimensional pseudocontinuous arterial spin labeling (3D-pcASL) perfusion imaging in the brain of children with Attention-deficit/hyperactivity disorder (ADHD). A total of 78 ADHD children aged 5-13 years were prospectively selected as the study group, and 89 healthy children matched in age and sex were selected as the control group. All children underwent MRI conventional sequence, 3D-pcASL, and 3D-T1 sequence scans. The brain gray and white matter volume and cerebral blood flow (CBF) perfusion values were obtained by software post-processing, and were compared and analyzed in the two groups to find out their characteristics in the brain of ADHD children. The total brain volume and total CBF values were lower in ADHD children than in healthy children (P < 0.05); the gray and white matter volumes in the frontal lobe, temporal lobe, hippocampus, caudate nucleus, putamen, globus pallidus and other brain regions were lower in ADHD children than in healthy children (P < 0.05); the gray matter CBF values in the frontal lobe, temporal lobe, hippocampus, caudate nucleus, putamen, globus pallidus and other brain regions were lower in ADHD children than in healthy children (P < 0.05); the differences between the white matter CBF values of white matter in the said brain regions of ADHD children and healthy children were not statistically significant (P > 0.05); and the CBF values in frontal lobe and caudate nuclei could distinguish ADHD children (AUC > 0.05, P < 0.05). The 3D-pcASL technique showed reduced cerebral perfusion in some brain regions of ADHD children.

Signal-to-noise ratio penalties from a loss of stimulated echoes when using slab-selective excitation in three-dimensional fast spin echo imaging with long echo trains.

Three-dimensional fast spin echo imaging with long echo trains combines high resolution with reasonable acquisition times and reduced specific absorption rate due tolow refocusing flip angles. Typically, an entire volume is encoded (nonselective excitation) or localization can be performed with slab select excitation, which uses a long 90° pulse for precise localization, followed by a preliminary nonselective 180° pulse bounded by spoiler gradients to destroy signal outside of the volume of interest. Subsequent flip angles in the train are nonselective and identical between the two methods. The inclusion of the initial selective pulse and spoiler gradients results in a signal-to-noise ratio (SNR) penalty for slab selection, beyond the slice-averaging dependence, arising from a loss of stimulated echoes. SNR differences are explored using Bloch equation simulations of a T2-weighted 96 echo train sequence with varying parameters including T2, T1, and B1+ and compared with phantom and in vivo brain, neck, and knee experiments. In vivo SNR measurements in the three regions showed a maximum decrease of selective SNR by 29% (gastrocnemius muscle), 25% (pons), and 22% (globus pallidus), despite similar experimental parameters to nonselective experiments. Decreased SNR was compounded by B1+ variation affecting prescribedflip angles with further smaller reductions with T2 and T1 times. In conclusion, the elimination of coherences via the preliminary nominal 180° pulse and spoiler gradients in addition to the extended echo timing from the long excitation pulse resulted in a reduction in SNR compared with the nonselective case. Consideration of the required SNR and chosen anatomy as well as sequence restrictions should be weighed before choosing slab-selective excitation.

Three-dimensional polarization state and spin structure of a tightly focused radially polarized Gaussian Schell-model beam

In this work, we revisit the tight focusing of a radially polarized partially coherent Gaussian Schell-model beam and examine the effect of spatial coherence of the incident beam on the focal-plane three-dimensional (3D) polarization characters, including the 3D degree of polarization, polarimetric dimensionality, and polarimetric structure. The polarimetric structure and the associated structure for the spin density vector of the tightly focused field are obtained via the 3D characteristic decomposition of the $3\ifmmode\times\else\texttimes\fi{}3$ polarization matrix. We demonstrate that the generated focused field shows the genuine 3D polarization state and a sophisticated spin structure due to the reduced spatial coherence in the incident beam. We find the contributions to whole 3D polarization state of the focused field from the pure state, middle-term state, and 3D unpolarized state in the characteristic decomposition, as well as the contributions to the total spin density vector from the spins of pure state and middle-term state can be controlled by the transverse spatial coherence width of the incident Gaussian Schell-model beam. In addition, the genuine 3D polarization and the spin structure are analyzed in the connection of the recently introduced concept of polarimetric nonregularity.

Prediction of short-term treatment outcome of nasopharyngeal carcinoma based on voxel incoherent motion imaging and arterial spin labeling quantitative parameters

PurposeTo evaluate the early response of chemoradiotherapy (CRT) in nasopharyngeal carcinoma (NPC) based on intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) and three-dimensional pseudo-continuous arterial spin labeling (3D pCASL). Materials and methodsForty patients diagnosed with NPC were recruited and divided into complete remission (CR) and partial remission (PR) group after CRT. All patients underwent IVIM and ASL and the related parameters was obtained. These parameters include pure diffusion coefficient (D), pseudo-diffusion coefficient (D*), perfusion fraction (f), average blood flow ( BFavg), minimum blood flow (BFmin), and maximum blood flow (BFmax). Student’s t test was used to compare the difference in ASL and IVIM derived parameters between CR and PR. The Areas under curve (AUC) of the receiver operating characteristic (ROC) was used to analyze the diagnostic performance of each parameter of ASL and IVIM to the treatment outcome. Resultsthe D value of IVIM in CR group was lower than that of the PR group ( P = 0.014),. Among the parameters of ASL, the BFavg and BFmax of the CR group were higher than those of the PR group(p = 0.004,0.013), but the BFmin had no statistical significance in the two groups（P = 0.54）. AUC of D, BFavg, and BFmax is about 0.731, 0.753, and 0.724, respectively, all of their combined AUC diagnosis was 0.812. ConclusionThe early response of NPC after CRT can predict by IVIM’s diffusion parameters and ASL-related blood flow parameters.

Quantum transport of a spin-1 chiral fermion

We theoretically study the quantum transport in a three-dimensional spin-1 chiral fermion system in the presence of impurity scattering. Within the self-consistent Born approximation, we find peak structure of the density of states and significant suppression of electrical conductivity around the zero energy. The zero-energy conductivity depends less on impurity concentration, unlike a Weyl fermion. These properties originate from the flat-band structure of the spin-1 chiral fermion.

Characteristic cerebral perfusion pattern in neuronal intranuclear inclusion disease.

Neuronal intranuclear inclusion disease (NIID), which pathogenesis remains largely unclear, is a neurodegenerative disease caused by GGC repeat expansion in NOTCH2NLC gene. As case studies have reported dynamic cortical perfusion changes in NIID, this study aimed to explore the cerebral perfusion pattern in NIID patients. A total of 38 NIID patients and 34 healthy controls (HCs) were recruited, and 2 NIID patients who had had episodic symptoms within 2 months were excluded. Data on demographic characteristics and clinical features were collected. All participants underwent three-dimensional pseudo-continuous arterial spin labeling perfusion magnetic resonance imaging (MRI) scanning. Voxel-based comparisons of cerebral blood flow (CBF) were conducted. NIID patients showed decreased perfusion in the cortex but increased perfusion in the deep brain regions compared with HCs. The regions with significant hypoperfusion were distributed in the bilateral frontal, temporal, parietal, and occipital gyri, with the left frontal gyrus being the most prominent. The regions with significant hyperperfusion included the bilateral basal ganglia, midbrain, pons, para-hippocampal, and parts of the bilateral cerebellum, fusiform, lingual, rectus, orbital, and cingulum anterior gyri, which were adjacent to the midline (all FDR-corrected p <0.05). When comparing the mean CBF value of the whole brain, no significant differences were observed between NIID patients and HCs (28.81 ± 10.1 vs. 27.99 ± 5.68 ml/100 g*min, p = 0.666). Voxel-based analysis showed no significant difference in cerebral perfusion between NIID patients with and without episodic symptoms. The perfusion within the bilateral middle frontal and anterior cingulate gyri showed positive correlations with MMSE and MoCA scores using age, sex, and education as covariates (p <0.005 uncorrected). NIID patients exhibited characteristic cortical hypoperfusion and deep brain hyperperfusion. The perfusion in the bilateral frontal lobe and cingulate gyrus was correlated with the severity of cognitive dysfunction. Cerebral perfusion change may be involved in NIID pathophysiology and serve as a potential indicator for monitoring NIID severity and progression.