Frontiers in neuroimaging最新文献

Introduction: Smoothing fMRI data prior to analysis is a fundamental and widely used technique to increase sensitivity. Unconstrained smoothing can also reduce the spatial specificity of the analysis by introducing artifacts in the data. This study tested the effects of smoothing on the reliability and accuracy of both task fMRI and resting state data. The effects of unconstrained smoothing were compared to those of an anatomically constrained smoothing method, which prevents smoothing across the white and gray matter surfaces of the cortex.

Methods: Unconstrained Gaussian smoothing and anatomically constrained smoothing were applied to simulated data, a sensory task fMRI dataset, a precision fMRI motor task mapping dataset, and a resting state fMRI dataset. Smoothing-related artifacts were tested for and compared between the smoothing methods, and the effects of the smoothing methods on the reliability and accuracy were measured.

Results: In the experiments with simulated data, unconstrained Gaussian smoothing demonstrated decreased accuracy and increased white matter activation compared to constrained smoothing. In the sensory task activation analysis, both Gaussian and constrained smoothing increased the reliability of the sensory task fMRI activations, but Gaussian smoothing increased the percentage of active voxels in the white matter relative to constrained smoothing (p < 0.001). Relative to constrained smoothing, Gaussian smoothing with FWHM > 3 mm also decreased the accuracy of motor mapping results from individual sessions to the precision maps (p < 0.001). With cluster significance thresholding, mean false positive voxel percentages remained below 5% for both methods across the tested kernel widths. Both Gaussian and constrained smoothing demonstrated a biasing effect on the resting state connectivity of nearby regions and on the graph theory metrics of the functional connectomes.

Conclusion: This study showed that unconstrained Gaussian smoothing spreads activation across cortical boundaries, increases white matter activation, and biases graph theory connectivity metrics. Anatomically constrained smoothing reduced some of these smoothing artifacts while still increasing reliability and may be a reasonable alternative to unconstrained Gaussian smoothing.

Background: GBCA-enhanced MRI is considered the gold standard for diagnosing intracranial tumors. However, concerns regarding gadolinium-based contrast agents (GBCAs) and workflow limitations have led to increasing interest in GBCA-free MRI techniques.

Objective: To compare the diagnostic performance of GBCA-free MRI with GBCA-enhanced MRI for detecting intracranial tumors within a neurological diagnostic pathway.

Methods: In this retrospective cohort study, 191 patients with 195 tumors (124 intra-axial and 71 extra-axial) and 410 controls were included from a regional brain tumor diagnostic pathway between 2013 and 2022. Three senior neuroradiologists independently assessed anonymized MRI scans. Each scan was first evaluated using GBCA-free sequences and subsequently reassessed using the full GBCA-enhanced protocol. Sensitivity, specificity, and inter-method agreement were calculated.

Results: GBCA-free MRI demonstrated a sensitivity of 79.6% and a specificity of 96.1%, whereas GBCA-enhanced MRI showed a sensitivity of 73.3% and a specificity of 92.9% (p = 0.15). Agreement between the two imaging approaches was substantial (κ = 0.699). Subgroup analyses showed comparable performance for intra-axial tumors, while both imaging approaches demonstrated modest sensitivity for extra-axial tumors.

Conclusion: GBCA-free MRI demonstrated diagnostic performance comparable to that of GBCA-enhanced MRI for detecting intracranial tumors. These findings suggest that GBCA-free MRI may serve as a reliable first-line screening tool within the neurological diagnostic pathway, reserving GBCA administration for cases requiring further lesion characterization.

Understanding how large-scale functional networks mature across development is essential for linking brain organization to cognition and behavior. Thus, the population-level organization of functional networks in children and how it compares to adult network architecture deserves further study. Using resting-state fMRI data from 7,316 children aged 9-10 years in the Adolescent Brain Cognitive Development (ABCD) Study, we mapped functional networks in matched discovery (n = 3,624) and replication (n = 3,692) cohorts in the cerebral cortex, basal ganglia, thalamus, and cerebellum. Functional connectivity and network topography were highly reproducible across child cohorts, demonstrating that large-scale network organization can be reliably estimated in childhood at the population scale. Comparisons with the adult Human Connectome Project (HCP; n = 1,000) dataset revealed reduced cross-age similarity compared to the within-age similarity. Our findings indicate that by late childhood, the global scaffold of brain networks approximates adult architecture with continued refinement, particularly in higher-order association systems. This large-scale, discovery-replication framework establishes a reproducible benchmark for cross-age functional network mapping, providing a foundation for longitudinal analyses of maturation across adolescence.

White matter (WM) has traditionally been considered structurally important but functionally inert in fMRI research. However, growing evidence indicates that WM exhibits meaningful BOLD fluctuations and participates in functional connectivity. Here, we investigate alterations in WM functional network connectivity (FNC) across the Alzheimer's disease (AD) spectrum using resting-state fMRI data from the Alzheimer's Disease Neuroimaging Initiative (ADNI; 415 cognitively normal (CN), 283 mild cognitive impairment (MCI), 91 AD). We applied a guided independent component analysis (ICA) approach based on a combined multiscale template including 202 intrinsic connectivity networks [ICNs; 97 WM, 105 gray matter (GM)] to estimate subject-specific timecourses and compute FNC. Group differences in WM-WM, GM-GM, and WM-GM functional network connectivity (AD-CN, AD-MCI, MCI-CN) were evaluated using two-sample t-tests on residual FNC values for age, sex, and mean framewise displacement. Multiple comparisons across edges were controlled using false discovery rate correction (q < 0.05), and effect sizes were quantified using Hedges' g. Results showed robust alterations in WM-WM and WM-GM connectivity in AD, particularly involving WM subcortical, frontal, sensorimotor, and occipitotemporal networks. Several WM-GM interactions with cerebellar and hippocampal GM networks were also disrupted, including reduced GM-cerebellar: WM-frontal coupling and increased GM-hippocampal: WM-frontal connectivity. Notably, MCI already showed WM-GM dysconnectivity relative to CN, suggesting that functional disruption of WM circuits emerges prior to overt dementia. These findings provide converging evidence that WM functional connectivity is both measurable and selectively altered across the AD continuum. Our findings support WM FNC as a candidate biomarker to GM-based measures for staging and monitoring AD. Together, these results position WM-GM dysconnectivity as an important systems-level signature of the AD continuum and support WM functional network connectivity as a promising complement to established GM-based measures for understanding disease progression.

Background: Schizophrenia (Sz) and autism spectrum disorder (ASD) are associated with reduced accuracy offace emotion recognition (FER). Nevertheless, the underlying pathophysiological mechanisms may diverge, potentially related to differential processing patterns within the early visual system. Here, we investigated physiological-level responses to emotional faces. We hypothesized that Sz and ASD would be associated with convergent behavioral performance, but divergent pathophysiological mechanisms.

Study design: Simultaneous eye-tracking and continuous EEG data were obtained from 23 adults diagnosed with schizophrenia (Sz), 21 autistic adults, and 24 neurotypical controls (NC) in response to intact and chimeric emotion faces. Event-related potentials (ERP) were calculated from the ongoing EEG data using time- and time-frequency (TF) domain approaches. Symptoms were rated using the Positive and Negative Symptom Scale (PANSS) and the Autism Diagnostic Observation Schedule, Second Edition (ADOS-2) in Sz and ASD, respectively.

Study results: As predicted, Sz and ASD were associated with similar levels of reduced FER accuracy relative to NC, but differential patterns of eye tracking and EEG-related activity. Rates of eye- vs. mouth-fixations were reduced across groups but did not correlate with FER. Nevertheless, the ability to utilize eye-information diverged across groups. Thus, when viewing chimeric faces, Sz was associated with reduced tendency to utilize eye information and increased tendency to utilize mouth information even when fixation location was considered. In TF analyses, reduced FER accuracy was associated with reduced initial sensory responses in Sz, as reflected in the theta-band time-frequency response. In contrast, in ASD, reduced FER accuracy was associated with increased alpha-frequency event-related desynchronization (alpha-ERD) consistent with hyper-engagement of secondary visual regions (V2). A combination of physiological and eye-tracking measures differentiated schizophrenia and ASD with >90% accuracy. V2 hyper-engagement in ASD correlated with both reduced FER accuracy and ADOS Social Interaction domain scores.

Conclusion: Schizophrenia and ASD are associated with divergent physiological-level alterations within the early visual system during emotional face processing, supporting models of magnocellular visual hypoactivity in schizophrenia but retinotectal visual hyperactivity leading to hyper-engagement of non-face regions (V2) by face stimuli in ASD. These alterations, in turn, may serve as targets for future intervention studies related to social cognition.

Introduction: Sudoku is a popular logic-based puzzle that requires sustained attention, working memory, and rule-based reasoning. Despite its widespread use, the neural processes supporting Sudoku play have not been systematically synthesised, limiting understanding of its potential applications beyond leisure.

Methods: This systematic review aimed to examine the neural correlates of Sudoku solving and to evaluate its potential relevance as a cognitive training paradigm. Six neuroimaging studies were included (five fMRI, and one fNIRS).

Results: Across haemodynamic studies, Sudoku solving consistently engaged frontoparietal networks, including the dorsolateral prefrontal cortex (DLPFC) and parietal regions implicated in executive control and visuospatial working memory, alongside activation of the anterior cingulate cortex (ACC), associated with performance monitoring and cognitive control.

Discussion: The included fNIRS study provided converging evidence of increased prefrontal activation during Sudoku solving under more ecologically valid conditions. Together, these findings suggest that Sudoku play recruits distributed neural systems supporting cognitive control, monitoring, and memory processes. While the limited number and heterogeneity of studies preclude firm conclusions regarding efficacy, the observed neural engagement highlights Sudoku as a candidate task for probing executive function and self-regulatory processes in both healthy and clinical populations.

Introduction: Fatigue is common in persons with Crohn's disease, negatively impacting quality of life in both active and remitted disease state. Neural correlates of fatigue in Crohn's disease are understudied, particularly relative to the separate impacts of physical, cognitive, and psychosocial fatigue. The potential moderating role of cortical complexity on the relationship between disease activity and fatigue has yet to be examined.

Methods: Forty-nine participants with Crohn's disease and 49 healthy control participants completed the Fatigue Impact Scale (which includes physical, cognitive, and psychosocial subscales) and whole-brain T1-weighted magnetic resonance imaging. Cortical complexity analyses were performed in CAT12, including within- and between-group analyses.

Results: In the Crohn's disease group, greater fatigue across all domains was associated with lower cortical complexity in the right superior temporal gyrus. Physical and cognitive impacts of fatigue were differently related to cortical complexity in the superior frontal and supramarginal gyri. Cortical complexity in the healthy control group was exclusively, positively, related to the physical impact of fatigue. The relationship between disease activity and fatigue varied relative to cortical complexity in the right superior temporal gyrus (ΔR² = 0.062, F = 5.558, p = 0.023) and the right superior frontal gyrus (ΔR² = 0.058, F = 4.059, p = 0.050).

Discussion: The present findings expand our understanding of the complex brain-gut interactions linking disease activity and fatigue in Crohn's disease relative to underlying differences in cortical complexity.

Objective: We aimed to investigate changes in whole-brain functional connectivity (FC) before and after electroconvulsive therapy (ECT) in adolescents with major depressive disorder (MDD) and suicidal ideation (SI).

Methods: Forty-nine adolescents with MDD and SI were enrolled, and resting-state functional magnetic resonance imaging (rs-fMRI) was performed at baseline and after ECT for each patient. Forty healthy controls (HCs) were scanned only at baseline. Region-of-interest (ROI)-based whole-brain FC analyses were used, with the left superior frontal gyrus (L-SFG) and right superior temporal gyrus (R-STG) as seed regions.

Results: Compared with HCs, MDD patients at baseline showed decreased FC between R-STG and left inferior occipital gyrus (L-IOG), and between L-SFG and right anterior cingulate gyrus (R-ACG). After ECT, MDD patients showed reduced FC between R-STG and right middle temporal gyrus (R-MTG), increased FC between L-SFG and right middle frontal gyrus (R-MFG), and decreased FC between L-SFG and right superior occipital gyrus (R-SOG)/right superior frontal gyrus (R-SFG). Pearson's correlation found that post-ECT Hamilton Depression Rating Scale-17 (HAMD-17) scores were negatively correlated with FC between R-STG and L-IOG.

Conclusion: Abnormal FC in the frontal-cingulate and frontal-temporal circuits may be a potential neurobiological basis of depressive and suicidal symptoms in adolescents. ECT may improve these symptoms by modulating FC in these key brain regions.

Cerebral infarction is the most common neurological complication in patients with hypereosinophilic syndromes (HES), typically occurring in border-zone regions. However, intracranial artery stenosis is rarely observed in HES, and the underlying mechanisms of cerebral infarction remain largely unknown. Here, we report a case of HES complicated by acute ischemic stroke secondary to severe stenosis of left middle cerebral artery (MCA). A diagnosis of idiopathic HES was established based on eosinophilia (14.08%) in bone marrow aspiration and negative genetic testing. Without contraindications, intravenous thrombolysis with alteplase was administered, resulting in a decrease of the National Institutes of Health Stroke Scale score from 13 to 2. High-resolution magnetic resonance imaging (HR-MRI) showed homogeneous, concentric wall thickening and enhancement in the terminal segments of the left internal carotid artery and at the origin of the MCA, indicating an inflammatory process. Follow-up HR-MRI at 17 months demonstrated a reduction in vessel wall enhancement after immunosuppressive therapy. Over the two-year follow-up period, the eosinophil count remained within the range of 0.22-1.09 × 10⁹/L, and no stroke recurrence was observed. In the literature review, only three cases of stroke associated with HES reported intracranial stenosis, all located in the M1 segment of the MCA. Their clinical outcomes improved following immunosuppressive therapy. Thus, intracranial large artery stenosis is a rare etiology of stroke in patients with HES. Homogeneous vessel wall enhancement on HR-MRI suggests an underlying vasculitis, which appears responsive to immunosuppressive therapy.

Introduction: Human 7T MRI systems are manufactured by three vendors (Siemens, Philips, and GE) who all provide equivalent head coils from the same 3rd party manufacturer. Furthermore, many 7T MRI sites have two head coils available for neuroimaging: a 1Tx32Rx head coil for conventional single-channel transmit imaging and an 8Tx32Rx head coil for parallel-transmit (pTx) imaging.

Methods: We compared the performance of these coils in six healthy volunteers. All scans were done on a 7T MRI (MAGNETOM Terra, Siemens, Germany). We tested seven sequences in wide use at our centre: B₀ and B₁ ⁺ mapping, anatomical T₁-weighted MP2RAGE, R₂*-mapping, single-voxel spectroscopy (MRS), echo-planar imaging time series, and diffusion tensor imaging (DTI). Sequences were run unmodified and without any pTx pulses.

Results: Data quality is comparable for both coils. The 8Tx32Rx coil had improved B₁ ⁺ in inferior brain regions, enhanced spinal cord visibility in the cervical spine on anatomical MP2RAGE, higher SNR in MRS of the brainstem, and more defined fitted white matter tracts in the DTI images. All sequences showed acceptable data quality with the 8Tx32Rx coil.

Conclusion: It is reasonable to substitute the 8Tx32Rx coil for the 1Tx32Rx coil for standard neuroimaging protocols. This will enable advanced parallel transmit sequences to be added to protocols with minimal disruption.