Search Results (60)

Background: Cognitive difficulties are common after SARS-CoV-2 infection, yet their neurobiological underpinnings remain uncertain. Cognitive symptoms in post-COVID-19 condition (PCC) are often characterised by attentional and executive dysfunction, although the relationship between subjective symptoms and objective neurobiological changes remains uncertain. Methods: Adults previously hospitalised with COVID-19 who reported persistent cognitive symptoms underwent neuropsychological testing and 3 T MRI. The protocol included high-resolution volumetric imaging, diffusion-based tractography, and magnetic resonance spectroscopy (MRS) of frontal white matter. Data were compared with age- and sex-matched controls from a pre-COVID-19 cohort and against pooled normative MRS datasets. Analyses adjusted for intracranial volume, sex, and time since infection, with false-discovery-rate correction. This study was exploratory and hypothesis-generating in design. Results: Thirty participants were recruited; twenty-nine completed MRI acquisition. Participants (mean age 58 years; 62% female; approximately two years post-infection) demonstrated selective impairments in attention, working memory, and verbal fluency. No widespread volumetric or white-matter differences were identified, although reduced posterior hypothalamic volume and altered occipito-parietal connectivity were observed. MRS demonstrated reduced N-acetylaspartate and elevated choline, myo-inositol, and glutamate-glutamine ratios relative to normative reference ranges. No significant associations were observed between imaging measures and cognitive or symptoms outcomes after correction. Conclusions: PCC is characterised by circumscribed cognitive changes and subtle neural differences, but these objective changes do not closely align with subjective symptom severity. This mismatch shares phenotypic features with functional cognitive disorder and suggests that post-COVID-19 “brain fog” is not driven by structural or neurochemical changes alone. Instead, it potentially reflects a combination of mild neurobiological effects and functional cognitive processes. Together, these findings highlight the importance of considering both brain-based and functional contributors to persistent cognitive complaints after SARS-CoV-2 infection. Full article

Background/Objectives: White matter (WM) tract detection is critical in the presurgical planning of tumor resection. However, standard-of-care imaging techniques including T₁-weighted, T₂-weighted, and Diffusion Tensor Imaging (DTI) often fail to identify WM tracts within edematous regions. In T₁/T₂-weighted imaging, edema increases extracellular water and reduces tissue contrast, and in diffusion-weighted imaging, edema elevates isotropic diffusion, reducing sensitivity to anisotropic diffusion along WM tracts. Advanced biophysical diffusion modeling techniques such as Neurite Orientation Dispersion and Density Imaging (NODDI) and the Standard Model (SM) address this limitation by compartmentalizing the diffusion signal into free-water, intra-neurite, and extra-neurite contributions. Here, we test if biophysical multi-compartment models can robustly identify WM tracts and recover tractography streamlines within edematous regions. Methods: In this study, we use multi-shell diffusion-weighted MRI data obtained from patients with meningiomas—a pathology allowing for isolation of the effects of edema without the confounding effects of tumor cell invasion. We compared FA from standard and free-water-corrected DTI, the orientation dispersion index (ODI) from NODDI, and P₂ (a scalar descriptor of fiber orientation coherence) from the SM fODF in edematous and unaffected contralateral WM regions. As a proof of concept, we visually evaluated the tractography performance across models. Results: Our results show that (1 − ODI) and P₂ values in edema remained close to within-subject contralateral measurements, contrasting with substantial reductions in FA and FW-FA. (1 − ODI) showed a small but statistically significant increase in edema (~8%, p = 0.02), while P₂ was unchanged. Conclusions: These results highlight the potential of biophysical diffusion models for preoperative mapping in edema. Full article

Background/Objectives: Preservation of critical white matter (WM) pathways is essential for maximizing surgical safety in neuro-oncology and functional neurosurgery. Constrained spherical deconvolution (CSD) offers superior modeling of complex fiber architecture compared to diffusion tensor imaging (DTI). This case series evaluates the clinical utility of CSD in surgical planning and intraoperative navigation. Methods: A retrospective review of 20 patients (15 brain tumors, 5 functional disorders) treated between September 2022, and September 2024 was performed. All patients underwent preoperative MRI with CSD-based reconstruction of eloquent WM tracts. Clinical presentation, tract involvement, surgical strategy, and postoperative outcomes were analyzed. Results: CSD reliably reconstructed CST, AF, IFOF, OT, and DRTT depending on tumor location or DBS target. Compared with standard DTI, CSD provided improved delineation of tract extent and tumor–tract interfaces. Gross total resection (GTR) was achieved in all tumor patients without new neurological deficits. DBS cases showed precise correlation between stimulation thresholds, side effects, and CSD-predicted distances to critical WM tracts. DRTT targeting resulted in marked clinical improvement in Holmes tremor. Conclusions: CSD enhances anatomical accuracy in WM tract visualization, supporting safer resections in eloquent areas and improving DBS targeting. Its integration into routine workflow may optimize neurosurgical outcomes. Full article

Background/Objectives: The posterior commissure (PC) and habenular commissure (HC) are fine-caliber midline fiber bundles located within the epithalamic roof of the third ventricle. Their small size and deep anatomical position render them vulnerable during fiber dissection, and it is difficult to delineate reliably with conventional diffusion MRI. To define a reproducible microsurgical strategy for three-dimensional exposure of the PC and HC, and to evaluate their tractographic representation using high-resolution diffusion template data. Methods: Four formalin-fixed adult cadaveric brains were prepared using a modified Klingler technique and underwent systematic microsurgical fiber dissection focused on preservation of the epithalamic roof and midline commissures. Diffusion MRI data from the Human Connectome Project (HCP-1065) were reconstructed in MNI space using q-space diffeomorphic reconstruction in DSI Studio to attempt deterministic tractographic reconstruction of the PC and HC. Results: In all specimens, the PC was identified as a compact transverse bundle superior to the rostral cerebral aqueduct within the inferior pineal lamina. The HC appeared as a thinner band superior to the pineal recess, interconnecting the bilateral habenular nuclei and separated from the PC by the hypothalamic sulcus. A midline-prioritized dissection sequence facilitated preservation of commissural continuity. Deterministic tractography reproduced adjacent peduncular trajectories but failed to consistently reconstruct discrete HC or PC streamlines. Conclusions: Cadaveric fiber dissection remains the most reliable method for studying the fine commissural anatomy of the epithalamus. A midline-first, roof-preserving strategy enhances visualization of the PC and HC and may have implications for posterior third ventricular surgery and stereotactic targeting. Full article

When people interact, their actions reflect mood, attitude, and intention. Stern termed the affective qualities conveyed by actions, such as gentleness or rudeness, Vitality Forms (VFs). Previous research shows that children with autism spectrum disorder (ASD) differ from neurotypical (NT) peers in both perceiving and expressing these fundamental aspects of communication. It remains unclear whether these differences arise from structural or connectivity alterations in brain regions involved in VF processing. This study investigated structural and microstructural brain differences between children with ASD and NT peers, focusing on the VF-related network, which includes the dorso-central insula (DCI), premotor cortex (PM), middle cingulate cortex (MCC), and dorsolateral prefrontal cortex (DLPFC). Structural MRI data were collected from 60 right-handed boys aged 6–10 years (30 ASD, 30 NT), with diffusion MRI data available for a subset (20 ASD, 20 NT). A multimodal approach combined voxel-based morphometry (VBM), tract-based spatial statistics (TBSS), and probabilistic tractography. VBM revealed increased grey-matter volume in the PM, DLPFC, and MCC in the ASD group, with no differences in the DCI. TBSS showed white-matter microstructural alterations in premotor-related pathways. Probabilistic tractography further indicated atypical organization of tracts connecting the PM with the DLPFC, MCC, and DCI in children with ASD. Overall, the findings suggest atypical development of the premotor cortex and its associated white-matter connections in ASD, supporting theoretical accounts that link this network to altered processing of affective action dynamics during social interaction. Full article

Minimally invasive parafascicular surgery (MIPS) represents a paradigm shift in the management of deep-seated brain tumors, enabling function-sparing resections previously limited to biopsy and/or medical therapy. Central to MIPS are structured frameworks guiding preoperative planning and intraoperative execution. The six-pillar concept—comprising imaging, navigation, atraumatic access, optics, resection, and postoperative care—provides a comprehensive approach to integrate advanced neuroimaging, tractography, tubular retractor systems, fluorescence-guided resection, and neuromonitoring to optimize functional outcomes. Five-point target-trajectory complex planning—craniotomy, outer radial corridor, inner radial corridor, target, and resection margins—translates preoperative imaging and functional mapping into a precise surgical trajectory, balancing maximal tumor resection with minimal disruption of eloquent brain structures. Preoperative assessment of tumor characteristics, vascular relationships, and cortical eloquence informs trajectory planning and intraoperative adjustments. A critical determinant of MIPS success is the intraoperative golden hour, referring to the high-risk period surrounding brain cannulation with a tubular retractor. Key principles include (1) precannulation system checks to ensure instrument readiness; (2) access injury prevention through optimized craniotomy sizing and sulcal preparation; (3) tubular-tumor targeting accuracy addressing brain and tubular translation, tumor displacement, and white-matter sleeves; and (4) intracranial pressure control strategies to minimize tissue strain and venous congestion. Overcoming this period enables a controlled resection phase guided by the above-mentioned surgical adjuncts. The six-pillar concept and five-point target-trajectory complex planning are the foundations of MIPS planning, whereas the intraoperative golden hour provides a roadmap for successful intraoperative delivery of the surgical plan. Full article

Purpose: This study aimed to investigate alterations in brain white matter fiber bundle integrity among older long-term breast cancer survivors treated with chemotherapy, with a focus on identifying potential neural correlates of cancer-related cognitive impairment (CRCI). Methods: Women aged 65 years and older were prospectively enrolled and divided into three groups: breast cancer survivors 5 to 15 years after chemotherapy treatment (C+), breast cancer survivors without chemotherapy (C−), and age–sex-matched healthy controls (HC). Participants underwent brain MRI with diffusion tensor imaging and cognitive testing at time point 1 (TP1) upon enrollment and again after two years at time point 2 (TP2). White matter fiber tract integrity was assessed using fractional anisotropy-based (FA) tractography across 80 major fiber bundles in the brain. Results: Over the two-year period, both C+ and C− groups exhibited significant reductions in white matter integrity with FA reductions noted in several fiber tracts, including the left inferior fronto-occipital fasciculus (C+ group: p < 0.01; C− group: p = 0.01), right inferior fronto-occipital fasciculus (p < 0.01), left inferior longitudinal fasciculus (C+ group: p < 0.01; C− group: p = 0.04), right inferior longitudinal fasciculus (C+ group: p = 0.04; C− group: p = 0.02), right vertical occipital fasciculus (C+ group: p < 0.02; C− group: p = 0.01), left anterior corticostriatal tracts (C+ group: p < 0.01; C− group: p = 0.02), right anterior corticostriatal tracts (C+ group: p = 0.01; C− group: p = 0.02), anterior commissure (C+ group: p = 0.01; C− group: p = 0.03), and forceps minor (C+ group: p = 0.03; C− group: p = 0.01). In addition, FA reductions were noted in the left superior longitudinal fasciculus (p < 0.01), uncinate fasciculus (p = 0.01), thalamic radiation (p = 0.04), left optic radiations (p = 0.04) and right optic radiations (p = 0.03) in the C+ group only. No significant changes over time were detected in the HC group (p > 0.05). The fiber tract changes were considered statistically significant at a threshold of p < 0.05, with family-wise error (FWE) correction. Significant positive correlation was found between the longitudinal changes in the right inferior fronto-occipital fasciculus and the fluid composite cognition score in the C+ group (R = 0.65 and p = 0.03; Pearson’s correlation). Conclusions: This study showed continued white matter fiber tract alterations in the older long-term breast cancer survivors who may have cognitive difficulties years after chemotherapy. Diffusion tensor imaging may provide valuable insights into the white matter microstructural correlates of CRCI in older cancer survivors. Full article

Background/Objectives: In recent years, MRI-based diffusion-weighted tractography techniques have uncovered additional white matter pathways that have significant roles in language processing and production. In this review, we aim to outline the major language centers of the brain and major language pathways along with association tracts that serve dual roles in both the language and limbic systems. According to the current dual-stream model of language processing, the brain’s language network is organized into a dorsal stream, responsible for mapping sound to articulation, and a ventral stream, which maps sound to meaning. Materials and Methods: The literature cited in this manuscript was identified through targeted searches of the PubMed database. Priority was given to peer-reviewed human studies, including original neuroimaging, cadaveric validation, and intraoperative stimulation studies. Non-peer-reviewed sources and publications lacking clear anatomical or functional correlation to language pathways were excluded. Results: Advances in functional MRI and diffusion weighted imaging techniques have revealed a more interconnected network, expanding our understanding beyond the classical dual-stream model of language processing. The Kamali limbic model proposed distinct ventral and dorsal limbic networks. Notably, several fiber pathways within the ventral limbic network may subserve both language and limbic functions. The association tracts with dual limbic-language functions form a critical basis for understanding the pathophysiology of language disorders accompanied by cognitive and emotional comorbidities observed in dyslexia, speech apraxia, aphasia, autism spectrum disorder, schizophrenia and post-traumatic stress disorder. Conclusions: Visualizing the language center and interconnected dual language and limbic fiber tracts highlights the importance of integrating language, executive function, and emotion in developing disease models and designing effective, targeted treatments for patients. Full article

Drug-resistant epilepsy affects nearly one-third of individuals with epilepsy and remains a major cause of neurological morbidity worldwide. Surgical intervention offers a potential cure, but its success critically depends on the precise identification of the epileptogenic zone and the preservation of eloquent cortical and subcortical regions. This review aims to provide a comprehensive synthesis of current evidence on the role of multimodal neuroimaging in the personalized presurgical evaluation and planning of epilepsy surgery. We analyze how structural, functional, metabolic, and electro-physiological imaging modalities contribute synergistically to improving localization accuracy and surgical outcomes. Structural MRI remains the cornerstone of presurgical assessment, with advanced sequences, post-processing techniques, and ultra-high-field (7 T) MRI enhancing lesion detection in previously MRI-negative cases. Functional and metabolic imaging, including FDG-PET, ictal/interictal SPECT, and arterial spin labeling MRI, offer complementary insights by revealing regions of altered metabolism or perfusion associated with seizure onset. Functional MRI enables non-invasive mapping of language, memory, and motor networks, while diffusion tensor imaging and tractography delineate critical white-matter pathways to minimize postoperative deficits. Electrophysiological integration through EEG source imaging and magnetoencephalography refines localization when combined with MRI and PET data, forming the basis of multimodal image integration platforms used for surgical navigation. Our review also briefly explores emerging intraoperative applications such as augmented and virtual reality, intraoperative MRI, and laser interstitial thermal therapy, as well as advances driven by artificial intelligence, such as automated lesion detection and predictive modeling of surgical outcomes. By consolidating recent developments and clinical evidence, this review underscores how multimodal imaging transforms epilepsy surgery from a lesion-centered to a patient-centered discipline. The purpose is to highlight best practices, identify evidence gaps, and outline future directions toward precision-guided, minimally invasive, and function-preserving neurosurgical strategies for patients with drug-resistant focal epilepsy. Full article

Background: Acquired brain injury (ABI) leads to cognitive, emotional, and social impairments that substantially affect quality of life. Although cortical lesions have traditionally received more attention, increasing evidence highlights the importance of the integrity of major white matter association tracts. However, few studies have simultaneously examined cognitive, affective, and social domains within a tractography framework. Methods: In this exploratory pilot study, ten ABI patients underwent diffusion-based tractography of the principal association tracts—the superior and inferior longitudinal fasciculi, the uncinate fasciculus, the inferior fronto-occipital fasciculus, and the cingulum—together with a comprehensive neuropsychological battery covering global cognition, executive functions, memory, emotional symptoms, and empathy. Results: Marked interindividual variability was observed in both tract profiles and neuropsychological outcomes. Findings revealed paradoxical associations, such as larger volumes of the left superior longitudinal fasciculus being linked to poorer cognitive performance, suggesting maladaptive reorganization. Hemispheric lateralization patterns were also identified, with the uncinate fasciculus showing differential contributions to immediate memory and working memory across hemispheres. Notably, empathy scores consistently correlated with volumes of the inferior longitudinal fasciculus, the uncinate fasciculus, and the cingulum, in line with recent evidence on the structural basis of socio-emotional outcomes after ABI. Conclusions: Although limited by sample size, this study provides novel evidence regarding the structure–function paradox, hemispheric specialization, and the clinical relevance of empathy in ABI. Overall, the results support the integration of tractography of the main association tracts with neuropsychological assessment as complementary tools to advance personalized neurorehabilitation. Full article

Several recent studies have utilized neuroimaging to delineate the localization and function of brain regions involved in language. However, many uncertainties persist regarding the organization of the linguistic system in the human brain. The aim of the present study was to characterize the structural changes produced in a sample of 9 patients with post-stroke aphasia (4 women; mean age = 60 years, SD = 14.86) and their relationship with performance in the entire Boston Diagnostic Aphasia Examination (BDAE). Magnetic Resonance Imaging was acquired from the brain of each patient and brain lesions were assessed. Disconnection’s severity of each white matter tract by embedding the lesion into the streamline tractography atlas of the Human Connectome Project was analyzed, and grey matter lesion load using a 7-Network Cortical parcellation template was estimated, with additional subcortical, cerebellar and brainstem parcels. Finally, all data obtained was correlated with performance in the BDAE. Somatomotor network correlated with repetition scale. The disconnection of the left acoustic radiation and inferior longitudinal fasciculus correlated with repetition sub-scale. Finally, the left U-fibers correlated with severity (a BDAE sub-scale that assesses the patient’s communicative skills), conversational speech and reading sub-scales. These findings emphasized that the disconnection of these fronto-parieto-temporal structures correlate with deficits in repetition, beyond the classical hypothesis attributing such deficits solely to the impairment of the arcuate fasciculus. Full article

Objectives: Breast cancer survivors often experience long-term neurological complications, including balance impairments, following treatment. This study aimed to investigate microstructural changes in white matter tracts in breast cancer survivors with balance impairment using diffusion tensor tractography. Methods: An open, single-center, prospective study was conducted including two groups—healthy age-matched volunteers (n = 28) and breast cancer survivors (n = 35) with balance impairment. All participants underwent diffusion tensor tractography at baseline and at the end of the follow-up period of six months. Quantitative anisotropy was analyzed using DSI Studio to assess white matter integrity. Results: At baseline, patients with balance impairment exhibited significantly reduced quantitative anisotropy values in the middle cerebellar peduncles (p = 0.046) and cerebellar hemispheres (p = 0.024, 0.055) compared to healthy controls. At the end of the follow-up, quantitative anisotropy values were increased across most tracts, though some differences persisted between groups (p < 0.001). Conclusions: Breast cancer survivors with balance impairment demonstrate sustained microstructural white matter changes, particularly in cerebellar and vestibular pathways. These findings suggest that diffusion tensor tractography can provide valuable insights into central nervous system alterations contributing to post-treatment balance dysfunction and may serve as a potential tool for early diagnosis and rehabilitation planning. Full article

Background: Acquired brain injury (ABI) often produces heterogeneous cognitive and emotional outcomes that are not fully explained by conventional neuropsychological testing. Diffusion tensor imaging (DTI) tractography may capture patient-specific patterns of white matter connectivity and thereby complement clinical assessment. Methods: We conducted an exploratory case series of nine patients in the subacute phase of ABI (traumatic brain injury or subarachnoid hemorrhage). Each underwent a brief cognitive-emotional battery and 1.5 T DTI with deterministic tractography of major association tracts and the corpus callosum. Tract lateralization was quantified using the Structural Asymmetry Index (SAI), and individual profiles were compared with neuropsychological and emotional data. Results: Six patients met criteria for clinically significant anxiety, and four for depression, often dissociated from global cognitive screening. Tractography revealed heterogeneous asymmetry patterns, most often in the superior longitudinal fasciculus, uncinate fasciculus, and cingulum. In several cases, structural asymmetries diverged from neuropsychological findings, suggesting dissociations between behavioral testing and connectivity-based measures. Conclusions: Within-subject tract asymmetry analysis provided preliminary, potentially clinically relevant information not captured by tests alone. These findings indicate that individualized tractography could enrich the interpretation of cognitive and emotional profiles and help guide hypothesis generation for connectivity-informed neurorehabilitation. Full article

Background: The epidermal growth factor receptor (EGFR) is an important factor in the behavior of diffuse glioma, serving as a potential biomarker for tumor aggressiveness and a therapeutic target. Diffusion tensor imaging (DTI) provides insights into the microstructural integrity of brain tissues, allowing for detailed visualization of tumor-induced changes in white matter tracts. This imaging technique can complement molecular pathology by correlating imaging findings with molecular markers and genetic profiles, potentially enhancing the understanding of tumor behavior and aiding in the formulation of targeted therapeutic strategies. The present study aimed to investigate the molecular properties of diffuse glioma based on DTI sequences. Methods: A total of 27 patients with diffuse glioma (in accordance with the WHO 2021 classification) were investigated using preoperative DTI sequences. The study was conducted using the tractography software DSI Studio (Hou versions 2025.04.16). Following the preprocessing of the raw data, volumes of the arcuate fasciculus (AF), frontal aslant tract (FAT), inferior fronto-occipital fasciculus (IFOF), superior longitudinal fasciculus (SLF), and uncinate fasciculus (UF) were reconstructed, and fractional anisotropy (FA) was derived. Molecular pathological examination was conducted to assess the presence of EGFR amplifications. Results: The mean age of patients was 56 ± 13 years, with 33% females. EGFR amplification was observed in 8/27 (29.6%) of cases. Following correction for multiple comparisons, FA in the left AF (p = 0.025) and in the left FAT (p = 0.020) was found to be significantly lowered in EGFR amplified glioma. In the right language network, however, no statistically significant changes were observed. Conclusions: EGFR amplification may be associated with lower white matter integrity of left hemispheric language tracts, possibly impairing neurological function and impacting surgical outcomes. The underlying molecular and cellular mechanisms driving this association require further investigation. Full article

Glioblastoma (GBM) often exhibits distinct anatomical patterns of relapse after radiotherapy. Tumour cell migration along myelinated white matter tracts is a key driver of disease progression. The failure of conventional imaging to capture subclinical infiltration has driven interest in advanced imaging biomarkers capable of quantifying tumour–brain interactions. Diffusion tensor imaging (DTI), radiomics, and connectomics represent a triad of innovative, non-invasive approaches that map white matter architecture, predict recurrence risk, and inform biologically guided treatment strategies. This review examines the biological rationale and clinical applications of DTI-based metrics, radiomic signatures, and tractography-informed connectomics in GBM. We discuss the integration of these modalities into machine learning frameworks and radiotherapy/surgical planning, supported by landmark studies and multi-institutional data. The implications for personalised neuro-oncology are profound, marking a shift towards risk-adaptive, tract-aware treatment strategies that may improve local control and preserve neurocognitive function. Full article