Association of Glymphatic and White Matter Impairment With the Postoperative Outcome of Pediatric Hydrocephalus.

BACKGROUND AND OBJECTIVES: Assessment of postoperative outcomes on pediatric hydrocephalus is critical for adjusting treatment strategies. The aim of this work was to investigate the ability of MRI metrics to predict postoperative outcomes. METHODS: A total of 55 children with hydrocephalus who underwent MRI and ventriculoperitoneal shunt surgery were prospectively enrolled. MRI was also performed at 6 months postoperatively in 33 of the 55 children. A total of 92 controls matched for age and sex were enrolled and divided into preoperative and postoperative control groups. We calculated the diffusion tensor imaging along the perivascular space (DTI-ALPS) index, Evans index, and diffusion tensor imaging metrics. The ability of various metrics to predict postoperative outcomes was assessed using receiver operating characteristic curve analysis. RESULTS: The DTI-ALPS index was significantly lower in patients with hydrocephalus than in controls. The abnormal DTI-ALPS index trended toward the normal range after surgery. Patients with lower preoperative DTI-ALPS index, lower fractional anisotropy (FA), and higher radial diffusivity in association fibers had less favorable short-term outcomes. Patients with worse long-term outcomes had lower postoperative DTI-ALPS index, higher postoperative Evans index, and lower FA and higher radial diffusivity in association fibers. Predictive performance was better when the DTI-ALPS index and FA in association fibers were used in combination than when either of these metrics was used alone. CONCLUSION: The DTI-ALPS index and FA in association fibers provided complementary information for prognostic assessment after the ventriculoperitoneal shunt surgery on pediatric hydrocephalus. A combination of DTI-ALPS index and FA would improve our ability to predict postoperative outcomes in these patients.

Magnetotransport spectroscopy of electroburnt graphene nanojunctions.

We have reported the precise methodology for fabricating graphene quantum dots through electroburning and performed measurements on the Coulomb blockade and oscillation phenomena. The diameters of graphene quantum dots can be estimated to range from several to tens of nanometers, utilizing the disk capacitance model and the two-dimensional quantum well model. By subjecting the quantum dots to a vertical magnetic field, an obvious alteration in conductance can be detected at the point of resonance tunneling. This observed phenomenon can be attributed to the modification in the density of states of Landau levels within the graphene leads. Moreover, by manipulating the gate voltage, it is possible to regulate the Fermi level of the lead, resulting in distinct magnetoresistance of different electron states. The presence of this lead effect may potentially disrupt the magnetic response analysis of graphene-based single-molecule transistors, necessitating a comprehensive theoretical examination to mitigate such interference.

Cortical mapping of callosal connections in healthy young adults.

The corpus callosum (CC) is the principal white matter bundle supporting communication between the two brain hemispheres. Despite its importance, a comprehensive mapping of callosal connections is still lacking. Here, we constructed the first bidirectional population-based callosal connectional atlas between the midsagittal section of the CC and the cerebral cortex of the human brain by means of diffusion-weighted imaging tractography. The estimated connectional topographic maps within this atlas have the most fine-grained spatial resolution, demonstrate histological validity, and were reproducible in two independent samples. This new resource, a complete and comprehensive atlas, will facilitate the investigation of interhemispheric communication and come with a user-friendly companion online tool (CCmapping) for easy access and visualization of the atlas.

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

Background: 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. Methods: 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. Results: 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). Conclusions: 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.

Experimental Observation of the Gate-Controlled Reversal of the Anomalous Hall Effect in the Intrinsic Magnetic Topological Insulator MnBi2Te4 Device.

Magnetic topological insulator, a platform for realizing quantum anomalous Hall effect, axion state, and other novel quantum transport phenomena, has attracted a lot of interest. Recently, it is proposed that MnBi2Te4 is an intrinsic magnetic topological insulator, which may overcome the disadvantages in the magnetic doped topological insulator, such as disorder. Here we report on the gate-reserved anomalous Hall effect (AHE) in the MnBi2Te4 thin film. By tuning the Fermi level using the top/bottom gate, the AHE loop gradually decreases to zero and the sign is reversed. The positive AHE exhibits distinct coercive fields compared with the negative AHE. It reaches a maximum inside the gap of the Dirac cone, and its amplitude exhibits a linear scaling with the longitudinal conductance. The positive AHE is attributed to the competition of the intrinsic Berry curvature and the extrinsic skew scattering. Its gate-controlled switching contributes a scheme for the topological spin field-effect transistors.