Medicine › Radiology, Nuclear Medicine and Imaging

Advanced Neuroimaging Techniques and Applications

Works Count: 52969

Wikipedia

Description

This cluster of papers focuses on the use of diffusion magnetic resonance imaging (MRI) to study the microstructural organization and connectivity of white matter in the brain. It covers topics such as tractography, brain connectivity, neuroimaging, and the development of brain microstructure using diffusion MRI techniques.

Keywords

Diffusion MRI; White Matter; Tractography; Brain Connectivity; Neuroimaging; Fiber Tractography; Brain Microstructure; Axonal Tracking; Anisotropic Water Diffusion; Brain Development

MR diffusion tensor spectroscopy and imaging

1994-01-01

Peter J. Basser , James Mattiello , D. LeBihan

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How to correct susceptibility distortions in spin-echo echo-planar images: application to diffusion tensor imaging

2003-09-22

Jesper Andersson , Stefan Skare , John Ashburner

A review of MRI findings in schizophrenia

2001-04-01

Martha E. Shenton , Chandlee C. Dickey , Melissa Frumin +1 more

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Q‐ball imaging

2004-11-23

David S. Tuch

Abstract Magnetic resonance diffusion tensor imaging (DTI) provides a powerful tool for mapping neural histoarchitecture in vivo. However, DTI can only resolve a single fiber orientation within each imaging voxel … Abstract Magnetic resonance diffusion tensor imaging (DTI) provides a powerful tool for mapping neural histoarchitecture in vivo. However, DTI can only resolve a single fiber orientation within each imaging voxel due to the constraints of the tensor model. For example, DTI cannot resolve fibers crossing, bending, or twisting within an individual voxel. Intravoxel fiber crossing can be resolved using q ‐space diffusion imaging, but q ‐space imaging requires large pulsed field gradients and time‐intensive sampling. It is also possible to resolve intravoxel fiber crossing using mixture model decomposition of the high angular resolution diffusion imaging (HARDI) signal, but mixture modeling requires a model of the underlying diffusion process. Recently, it has been shown that the HARDI signal can be reconstructed model‐independently using a spherical tomographic inversion called the Funk–Radon transform, also known as the spherical Radon transform. The resulting imaging method, termed q ‐ball imaging, can resolve multiple intravoxel fiber orientations and does not require any assumptions on the diffusion process such as Gaussianity or multi‐Gaussianity. The present paper reviews the theory of q ‐ball imaging and describes a simple linear matrix formulation for the q ‐ball reconstruction based on spherical radial basis function interpolation. Open aspects of the q ‐ball reconstruction algorithm are discussed. Magn Reson Med 52:1358–1372, 2004. © 2004 Wiley‐Liss, Inc.

Diffusion tensor imaging detects and differentiates axon and myelin degeneration in mouse optic nerve after retinal ischemia

2003-10-15

Sheng‐Kwei Song , Shu‐Wei Sun , Won‐Kyu Ju +3 more

Probabilistic diffusion tractography with multiple fibre orientations: What can we gain?

2006-10-28

Timothy E.J. Behrens , Heidi Johansen‐Berg , Saâd Jbabdi +2 more

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Robust determination of the fibre orientation distribution in diffusion MRI: Non-negativity constrained super-resolved spherical deconvolution

2007-02-22

Jacques‐Donald Tournier , Fernando Calamante , Alan Connelly

Diffusion Tensor Imaging of the Brain

2007-06-27

Andrew L. Alexander , Jee Eun Lee , Mariana Lazar +1 more

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Advances in functional and structural MR image analysis and implementation as FSL

2004-01-01

Stephen M. Smith , Mark Jenkinson , Mark W. Woolrich +7 more

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Rich-Club Organization of the Human Connectome

2011-11-02

Martijn P. van den Heuvel , Olaf Sporns

The human brain is a complex network of interlinked regions. Recent studies have demonstrated the existence of a number of highly connected and highly central neocortical hub regions, regions that … The human brain is a complex network of interlinked regions. Recent studies have demonstrated the existence of a number of highly connected and highly central neocortical hub regions, regions that play a key role in global information integration between different parts of the network. The potential functional importance of these "brain hubs" is underscored by recent studies showing that disturbances of their structural and functional connectivity profile are linked to neuropathology. This study aims to map out both the subcortical and neocortical hubs of the brain and examine their mutual relationship, particularly their structural linkages. Here, we demonstrate that brain hubs form a so-called "rich club," characterized by a tendency for high-degree nodes to be more densely connected among themselves than nodes of a lower degree, providing important information on the higher-level topology of the brain network. Whole-brain structural networks of 21 subjects were reconstructed using diffusion tensor imaging data. Examining the connectivity profile of these networks revealed a group of 12 strongly interconnected bihemispheric hub regions, comprising the precuneus, superior frontal and superior parietal cortex, as well as the subcortical hippocampus, putamen, and thalamus. Importantly, these hub regions were found to be more densely interconnected than would be expected based solely on their degree, together forming a rich club. We discuss the potential functional implications of the rich-club organization of the human connectome, particularly in light of its role in information integration and in conferring robustness to its structural core.

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The Human Connectome Project: A data acquisition perspective

2012-02-17

David C. Van Essen , Kâmil Uğurbil , Edward J. Auerbach +7 more

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Estimation of the Effective Self-Diffusion Tensor from the NMR Spin Echo

1994-03-01

Peter J. Basser , James Mattiello , D. LeBihan

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NODDI: Practical in vivo neurite orientation dispersion and density imaging of the human brain

2012-03-30

Hui Zhang , Torben Schneider , Claudia A. M. Gandini Wheeler‐Kingshott +1 more

Fiber tracking: principles and strategies – a technical review

2002-11-01

Susumu Mori , Peter C.M. van Zijl

Abstract The state of the art of reconstruction of the axonal tracts in the central nervous system (CNS) using diffusion tensor imaging (DTI) is reviewed. This relatively new technique has … Abstract The state of the art of reconstruction of the axonal tracts in the central nervous system (CNS) using diffusion tensor imaging (DTI) is reviewed. This relatively new technique has generated much enthusiasm and high expectations because it presently is the only approach available to non‐invasively study the three‐dimensional architecture of white matter tracts. While there is no doubt that DTI fiber tracking is providing exciting new opportunities to study CNS anatomy, it is very important to understand its limitations. In this review we therefore assess the basic principles and the assumptions that need to be made for each step of the study, including both data acquisition and the elaborate fiber reconstruction algorithms. Special attention is paid to situations where complications may arise, and possible solutions are reviewed. Validation issues and potential future directions and improvements are also discussed. Copyright © 2002 John Wiley & Sons, Ltd.

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Dysmyelination Revealed through MRI as Increased Radial (but Unchanged Axial) Diffusion of Water

2002-11-01

Sheng‐Kwei Song , Shu‐Wei Sun , Michael J. Ramsbottom +3 more

Automated Anatomical Labeling of Activations in SPM Using a Macroscopic Anatomical Parcellation of the MNI MRI Single-Subject Brain

2002-01-01

N. Tzourio-Mazoyer , Brigitte Landeau , Dimitri Papathanassiou +5 more

The basis of anisotropic water diffusion in the nervous system – a technical review

2002-11-01

Christian Beaulieu

Abstract Anisotropic water diffusion in neural fibres such as nerve, white matter in spinal cord, or white matter in brain forms the basis for the utilization of diffusion tensor imaging … Abstract Anisotropic water diffusion in neural fibres such as nerve, white matter in spinal cord, or white matter in brain forms the basis for the utilization of diffusion tensor imaging (DTI) to track fibre pathways. The fact that water diffusion is sensitive to the underlying tissue microstructure provides a unique method of assessing the orientation and integrity of these neural fibres, which may be useful in assessing a number of neurological disorders. The purpose of this review is to characterize the relationship of nuclear magnetic resonance measurements of water diffusion and its anisotropy (i.e. directional dependence) with the underlying microstructure of neural fibres. The emphasis of the review will be on model neurological systems both in vitro and in vivo . A systematic discussion of the possible sources of anisotropy and their evaluation will be presented followed by an overview of various studies of restricted diffusion and compartmentation as they relate to anisotropy. Pertinent pathological models, developmental studies and theoretical analyses provide further insight into the basis of anisotropic diffusion and its potential utility in the nervous system. Copyright © 2002 John Wiley & Sons, Ltd.

Bayesian analysis of neuroimaging data in FSL

2008-11-14

Mark W. Woolrich , Saâd Jbabdi , Brian Patenaude +6 more

Perisylvian language networks of the human brain

2004-12-13

Marco Catani , Derek K. Jones , Dominic ffytche

Abstract Early anatomically based models of language consisted of an arcuate tract connecting Broca's speech and Wernicke's comprehension centers; a lesion of the tract resulted in conduction aphasia. However, the … Abstract Early anatomically based models of language consisted of an arcuate tract connecting Broca's speech and Wernicke's comprehension centers; a lesion of the tract resulted in conduction aphasia. However, the heterogeneous clinical presentations of conduction aphasia suggest a greater complexity of perisylvian anatomical connections than allowed for in the classical anatomical model. This article re‐explores perisylvian language connectivity using in vivo diffusion tensor magnetic resonance imaging tractography. Diffusion tensor magnetic resonance imaging data from 11 right‐handed healthy male subjects were averaged, and the arcuate fasciculus of the left hemisphere reconstructed from this data using an interactive dissection technique. Beyond the classical arcuate pathway connecting Broca's and Wernicke's areas directly, we show a previously undescribed, indirect pathway passing through inferior parietal cortex. The indirect pathway runs parallel and lateral to the classical arcuate fasciculus and is composed of an anterior segment connecting Broca's territory with the inferior parietal lobe and a posterior segment connecting the inferior parietal lobe to Wernicke's territory. This model of two parallel pathways helps explain the diverse clinical presentations of conduction aphasia. The anatomical findings are also relevant to the evolution of language, provide a framework for Lichtheim's symptom‐based neurological model of aphasia, and constrain, anatomically, contemporary connectionist accounts of language. Ann Neurol 2005

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Stereotaxic Display of Brain Lesions

2000-01-01

Chris Rorden , Matthew Brett

Traditionally lesion location has been reported using standard templates, text based descriptions or representative raw slices from the patient′s CT or MRI scan. Each of these methods has drawbacks for … Traditionally lesion location has been reported using standard templates, text based descriptions or representative raw slices from the patient′s CT or MRI scan. Each of these methods has drawbacks for the display of neuroanatomical data. One solution is to display MRI scans in the same stereotaxic space popular with researchers working in functional neuroimaging. Presenting brains in this format is useful as the slices correspond to the standard anatomical atlases used by neuroimagers. In addition, lesion position and volume are directly comparable across patients. This article describes freely available software for presenting stereotaxically aligned patient scans. This article focuses on MRI scans, but many of these tools are also applicable to other modalities (e.g. CT, PET and SPECT). We suggest that this technique of presenting lesions in terms of images normalized to standard stereotaxic space should become the standard for neuropsychological studies.

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Reproducibility of quantitative tractography methods applied to cerebral white matter

2007-03-21

Setsu Wakana , Arvind Caprihan , Martina M. Panzenboeck +7 more

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MR signal abnormalities at 1.5 T in Alzheimer's dementia and normal aging

1987-08-01

Franz Fazekas , J. Chawluk , Abass Alavi +2 more

The type, frequency, and extent of MR signal abnormalities in Alzheimer's disease and normal aging are a subject of controversy. With a 1.5-MR unit we studied 12 Alzheimer patients, four … The type, frequency, and extent of MR signal abnormalities in Alzheimer's disease and normal aging are a subject of controversy. With a 1.5-MR unit we studied 12 Alzheimer patients, four subjects suffering from multiinfarct dementia and nine age-matched controls. Punctate or early confluent high-signal abnormalities in the deep white matter, noted in 60% of both Alzheimer patients and controls, were unrelated to the presence of hypertension or other vascular risk factors. A significant number of Alzheimer patients exhibited a more extensive smooth "halo" of periventricular hyperintensity when compared with controls (p = .024). Widespread deep white-matter hyperintensity (two patients) and extensive, irregular periventricular hyperintensity (three patients) were seen in multiinfarct dementia. Areas of high signal intensity affecting hippocampal and sylvian cortex were also present in five Alzheimer and two multiinfarct dementia patients, but absent in controls. Discrete, small foci of deep white-matter hyperintensity are not characteristic of Alzheimer's disease nor do they appear to imply a vascular cause for the dementing illness. The frequently observed "halo" of periventricular hyperintensity in Alzheimer's disease may be of diagnostic importance. High-signal abnormalities in specific cortical regions are likely to reflect disease processes localized to those structures.

Resting-State Functional Connectivity Reflects Structural Connectivity in the Default Mode Network

2008-04-09

Michael D. Greicius , Kaustubh Supekar , Vinod Menon +1 more

Resting-state functional connectivity magnetic resonance imaging (fcMRI) studies constitute a growing proportion of functional brain imaging publications. This approach detects temporal correlations in spontaneous blood oxygen level-dependent (BOLD) signal oscillations … Resting-state functional connectivity magnetic resonance imaging (fcMRI) studies constitute a growing proportion of functional brain imaging publications. This approach detects temporal correlations in spontaneous blood oxygen level-dependent (BOLD) signal oscillations while subjects rest quietly in the scanner. Although distinct resting-state networks related to vision, language, executive processing, and other sensory and cognitive domains have been identified, considerable skepticism remains as to whether resting-state functional connectivity maps reflect neural connectivity or simply track BOLD signal correlations driven by nonneural artifact. Here we combine diffusion tensor imaging (DTI) tractography with resting-state fcMRI to test the hypothesis that resting-state functional connectivity reflects structural connectivity. These 2 modalities were used to investigate connectivity within the default mode network, a set of brain regions--including medial prefrontal cortex (MPFC), medial temporal lobes (MTLs), and posterior cingulate cortex (PCC)/retropslenial cortex (RSC)--implicated in episodic memory processing. Using seed regions from the functional connectivity maps, the DTI analysis revealed robust structural connections between the MTLs and the retrosplenial cortex whereas tracts from the MPFC contacted the PCC (just rostral to the RSC). The results demonstrate that resting-state functional connectivity reflects structural connectivity and that combining modalities can enrich our understanding of these canonical brain networks.

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Diffusion tensor MR imaging of the human brain.

1996-12-01

Carlo Pierpaoli , Peter Jezzard , Peter J. Basser +2 more

To assess intrinsic properties of water diffusion in normal human brain by using quantitative parameters derived from the diffusion tensor, D, which are insensitive to patient orientation.Maps of the principal … To assess intrinsic properties of water diffusion in normal human brain by using quantitative parameters derived from the diffusion tensor, D, which are insensitive to patient orientation.Maps of the principal diffusivities of D, of Trace(D), and of diffusion anisotropy indices were calculated in eight healthy adults from 31 multisection, interleaved echo-planar diffusion-weighted images acquired in about 25 minutes.No statistically significant differences in Trace(D) (approximately 2,100 x 10(-6) mm2/sec) were found within normal brain parenchyma, except in the cortex, where Trace(D) was higher. Diffusion anisotropy varied widely among different white matter regions, reflecting differences in fiber-tract architecture. In the corpus callosum and pyramidal tracts, the ratio of parallel to perpendicular diffusivities was approximately threefold higher than previously reported, and diffusion appeared cylindrically symmetric. However, in other white matter regions, particularly in the centrum semiovale, diffusion anisotropy was low, and cylindrical symmetry was not observed. Maps of parameters derived from D were also used to segment tissues based on their diffusion properties.A quantitative characterization of water diffusion in anisotropic, heterogeneously oriented tissues is clinically feasible. This should improve the neuroradiologic assessment of a variety of gray and white matter disorders.

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Non-invasive mapping of connections between human thalamus and cortex using diffusion imaging

2003-06-13

Timothy E.J. Behrens , Heidi Johansen‐Berg , Mark W. Woolrich +7 more

Diffusional kurtosis imaging: The quantification of non‐gaussian water diffusion by means of magnetic resonance imaging

2005-05-19

Jens H. Jensen , Joseph A. Helpern , Anita Ramani +2 more

Abstract A magnetic resonance imaging method is presented for quantifying the degree to which water diffusion in biologic tissues is non‐Gaussian. Since tissue structure is responsible for the deviation of … Abstract A magnetic resonance imaging method is presented for quantifying the degree to which water diffusion in biologic tissues is non‐Gaussian. Since tissue structure is responsible for the deviation of water diffusion from the Gaussian behavior typically observed in homogeneous solutions, this method provides a specific measure of tissue structure, such as cellular compartments and membranes. The method is an extension of conventional diffusion‐weighted imaging that requires the use of somewhat higher b values and a modified image postprocessing procedure. In addition to the diffusion coefficient, the method provides an estimate for the excess kurtosis of the diffusion displacement probability distribution, which is a dimensionless metric of the departure from a Gaussian form. From the study of six healthy adult subjects, the excess diffusional kurtosis is found to be significantly higher in white matter than in gray matter, reflecting the structural differences between these two types of cerebral tissues. Diffusional kurtosis imaging is related to q ‐space imaging methods, but is less demanding in terms of imaging time, hardware requirements, and postprocessing effort. It may be useful for assessing tissue structure abnormalities associated with a variety of neuropathologies. Magn Reson Med 53:1432–1440, 2005. © 2005 Wiley‐Liss, Inc.

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White matter integrity, fiber count, and other fallacies: The do's and don'ts of diffusion MRI

2012-07-23

Derek K. Jones , Thomas R. Knösche , Robert Turner

Diffusion tensor imaging: Concepts and applications

2001-03-21

Denis Le Bihan , Jean‐François Mangin , Cyril Poupon +4 more

Abstract The success of diffusion magnetic resonance imaging (MRI) is deeply rooted in the powerful concept that during their random, diffusion‐driven displacements molecules probe tissue structure at a microscopic scale … Abstract The success of diffusion magnetic resonance imaging (MRI) is deeply rooted in the powerful concept that during their random, diffusion‐driven displacements molecules probe tissue structure at a microscopic scale well beyond the usual image resolution. As diffusion is truly a three‐dimensional process, molecular mobility in tissues may be anisotropic, as in brain white matter. With diffusion tensor imaging (DTI), diffusion anisotropy effects can be fully extracted, characterized, and exploited, providing even more exquisite details on tissue microstructure. The most advanced application is certainly that of fiber tracking in the brain, which, in combination with functional MRI, might open a window on the important issue of connectivity. DTI has also been used to demonstrate subtle abnormalities in a variety of diseases (including stroke, multiple sclerosis, dyslexia, and schizophrenia) and is currently becoming part of many routine clinical protocols. The aim of this article is to review the concepts behind DTI and to present potential applications. J. Magn. Reson. Imaging 2001;13:534–546. © 2001 Wiley‐Liss, Inc.

Intrinsic Functional Connectivity As a Tool For Human Connectomics: Theory, Properties, and Optimization

2009-11-05

Koene R. A. Van Dijk , Trey Hedden , Archana Venkataraman +3 more

Resting state functional connectivity MRI (fcMRI) is widely used to investigate brain networks that exhibit correlated fluctuations. While fcMRI does not provide direct measurement of anatomic connectivity, accumulating evidence suggests … Resting state functional connectivity MRI (fcMRI) is widely used to investigate brain networks that exhibit correlated fluctuations. While fcMRI does not provide direct measurement of anatomic connectivity, accumulating evidence suggests it is sufficiently constrained by anatomy to allow the architecture of distinct brain systems to be characterized. fcMRI is particularly useful for characterizing large-scale systems that span distributed areas (e.g., polysynaptic cortical pathways, cerebro-cerebellar circuits, cortical-thalamic circuits) and has complementary strengths when contrasted with the other major tool available for human connectomics—high angular resolution diffusion imaging (HARDI). We review what is known about fcMRI and then explore fcMRI data reliability, effects of preprocessing, analysis procedures, and effects of different acquisition parameters across six studies ( n = 98) to provide recommendations for optimization. Run length (2–12 min), run structure (1 12-min run or 2 6-min runs), temporal resolution (2.5 or 5.0 s), spatial resolution (2 or 3 mm), and the task (fixation, eyes closed rest, eyes open rest, continuous word-classification) were varied. Results revealed moderate to high test-retest reliability. Run structure, temporal resolution, and spatial resolution minimally influenced fcMRI results while fixation and eyes open rest yielded stronger correlations as contrasted to other task conditions. Commonly used preprocessing steps involving regression of nuisance signals minimized nonspecific (noise) correlations including those associated with respiration. The most surprising finding was that estimates of correlation strengths stabilized with acquisition times as brief as 5 min. The brevity and robustness of fcMRI positions it as a powerful tool for large-scale explorations of genetic influences on brain architecture. We conclude by discussing the strengths and limitations of fcMRI and how it can be combined with HARDI techniques to support the emerging field of human connectomics.

An integrated approach to correction for off-resonance effects and subject movement in diffusion MR imaging

2015-10-24

Jesper Andersson , Stamatios N. Sotiropoulos

In this paper we describe a method for retrospective estimation and correction of eddy current (EC)-induced distortions and subject movement in diffusion imaging. In addition a susceptibility-induced field can be … In this paper we describe a method for retrospective estimation and correction of eddy current (EC)-induced distortions and subject movement in diffusion imaging. In addition a susceptibility-induced field can be supplied and will be incorporated into the calculations in a way that accurately reflects that the two fields (susceptibility- and EC-induced) behave differently in the presence of subject movement. The method is based on registering the individual volumes to a model free prediction of what each volume should look like, thereby enabling its use on high b-value data where the contrast is vastly different in different volumes. In addition we show that the linear EC-model commonly used is insufficient for the data used in the present paper (high spatial and angular resolution data acquired with Stejskal-Tanner gradients on a 3T Siemens Verio, a 3T Siemens Connectome Skyra or a 7T Siemens Magnetome scanner) and that a higher order model performs significantly better. The method is already in extensive practical use and is used by four major projects (the WU-UMinn HCP, the MGH HCP, the UK Biobank and the Whitehall studies) to correct for distortions and subject movement.

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MR imaging of intravoxel incoherent motions: application to diffusion and perfusion in neurologic disorders.

1986-11-01

Denis Le Bihan , Élodie Breton , D Lallemand +3 more

Molecular diffusion and microcirculation in the capillary network result in a distribution of phases in a single voxel in the presence of magnetic field gradients. This distribution produces a spin-echo … Molecular diffusion and microcirculation in the capillary network result in a distribution of phases in a single voxel in the presence of magnetic field gradients. This distribution produces a spin-echo attenuation. The authors have developed a magnetic resonance (MR) method to image such intravoxel incoherent motions (IVIMs) by using appropriate gradient pulses. Images were generated at 0.5 T in a high-resolution, multisection mode. Diffusion coefficients measured on images of water and acetone phantoms were consistent with published values. Images obtained in the neurologic area from healthy subjects and patients were analyzed in terms of an apparent diffusion coefficient (ADC) incorporating the effect of all IVIMs. Differences were found between various normal and pathologic tissues. The ADC of in vivo water differed from the diffusion coefficient of pure water. Results were assessed in relation to water compartmentation in biologic tissues (restricted diffusion) and tissue perfusion. Nonuniform slow flow of cerebrospinal fluid appeared as a useful feature on IVIM images. Observation of these motions may significantly extend the diagnostic capabilities of MR imaging.

Predicting human resting-state functional connectivity from structural connectivity

2009-02-03

Christopher J. Honey , Olaf Sporns , Leila Cammoun +4 more

In the cerebral cortex, the activity levels of neuronal populations are continuously fluctuating. When neuronal activity, as measured using functional MRI (fMRI), is temporally coherent across 2 populations, those populations … In the cerebral cortex, the activity levels of neuronal populations are continuously fluctuating. When neuronal activity, as measured using functional MRI (fMRI), is temporally coherent across 2 populations, those populations are said to be functionally connected. Functional connectivity has previously been shown to correlate with structural (anatomical) connectivity patterns at an aggregate level. In the present study we investigate, with the aid of computational modeling, whether systems-level properties of functional networks--including their spatial statistics and their persistence across time--can be accounted for by properties of the underlying anatomical network. We measured resting state functional connectivity (using fMRI) and structural connectivity (using diffusion spectrum imaging tractography) in the same individuals at high resolution. Structural connectivity then provided the couplings for a model of macroscopic cortical dynamics. In both model and data, we observed (i) that strong functional connections commonly exist between regions with no direct structural connection, rendering the inference of structural connectivity from functional connectivity impractical; (ii) that indirect connections and interregional distance accounted for some of the variance in functional connectivity that was unexplained by direct structural connectivity; and (iii) that resting-state functional connectivity exhibits variability within and across both scanning sessions and model runs. These empirical and modeling results demonstrate that although resting state functional connectivity is variable and is frequently present between regions without direct structural linkage, its strength, persistence, and spatial statistics are nevertheless constrained by the large-scale anatomical structure of the human cerebral cortex.

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A New Rating Scale for Age-Related White Matter Changes Applicable to MRI and CT

2001-06-01

Lars‐Olof Wahlund , Frederik Barkhof , Franz Fazekas +7 more

Background and Purpose —MRI is more sensitive than CT for detection of age-related white matter changes (ARWMC). Most rating scales estimate the degree and distribution of ARWMC either on CT … Background and Purpose —MRI is more sensitive than CT for detection of age-related white matter changes (ARWMC). Most rating scales estimate the degree and distribution of ARWMC either on CT or on MRI, and they differ in many aspects. This makes it difficult to compare CT and MRI studies. To be able to study the evolution and possible effect of drug treatment on ARWMC in large patient samples, it is necessary to have a rating scale constructed for both MRI and CT. We have developed and evaluated a new scale and studied ARWMC in a large number of patients examined with both MRI and CT. Methods —Seventy-seven patients with ARWMC on either CT or MRI were recruited and a complementary examination (MRI or CT) performed. The patients came from 4 centers in Europe, and the scans were rated by 4 raters on 1 occasion with the new ARWMC rating scale. The interrater reliability was evaluated by using κ statistics. The degree and distribution of ARWMC in CT and MRI scans were compared in different brain areas. Results —Interrater reliability was good for MRI (κ=0.67) and moderate for CT (κ=0.48). MRI was superior in detection of small ARWMC, whereas larger lesions were detected equally well with both CT and MRI. In the parieto-occipital and infratentorial areas, MRI detected significantly more ARWMC than did CT. In the frontal area and basal ganglia, no differences between modalities were found. When a fluid-attenuated inversion recovery sequence was used, MRI detected significantly more lesions than CT in frontal and parieto-occipital areas. No differences were found in basal ganglia and infratentorial areas. Conclusions —We present a new ARWMC scale applicable to both CT and MRI that has almost equal sensitivity, except for certain regions. The interrater reliability was slightly better for MRI, as was the detectability of small lesions.

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The influence of head motion on intrinsic functional connectivity MRI

2011-07-26

Koene R. A. Van Dijk , Mert R. Sabuncu , Randy L. Buckner

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Microstructural and Physiological Features of Tissues Elucidated by Quantitative-Diffusion-Tensor MRI

1996-06-01

Peter J. Basser , Carlo Pierpaoli

Automatic 3D Intersubject Registration of MR Volumetric Data in Standardized Talairach Space

1994-03-01

D. Louis Collins , P. Neelin , Terrence M. Peters +1 more

In both diagnostic and research applications, the interpretation of MR images of the human brain is facilitated when different data sets can be compared by visual inspection of equivalent anatomical … In both diagnostic and research applications, the interpretation of MR images of the human brain is facilitated when different data sets can be compared by visual inspection of equivalent anatomical planes. Quantitative analysis with predefined atlas templates often requires the initial alignment of atlas and image planes. Unfortunately, the axial planes acquired during separate scanning sessions are often different in their relative position and orientation, and these slices are not coplanar with those in the atlas. We have developed a completely automatic method to register a given volumetric data set with Talairach stereotaxic coordinate system.The registration method is based on multi-scale, three-dimensional (3D) cross-correlation with an average (n > 300) MR brain image volume aligned with the Talariach stereotaxic space. Once the data set is re-sampled by the transformation recovered by the algorithm, atlas slices can be directly superimposed on the corresponding slices of the re-sampled volume. the use of such a standardized space also allows the direct comparison, voxel to voxel, of two or more data sets brought into stereotaxic space.With use of a two-tailed Student t test for paired samples, there was no significant difference in the transformation parameters recovered by the automatic algorithm when compared with two manual landmark-based methods (p > 0.1 for all parameters except y-scale, where p > 0.05). Using root-mean-square difference between normalized voxel intensities as an unbiased measure of registration, we show that when estimated and averaged over 60 volumetric MR images in standard space, this measure was 30% lower for the automatic technique than the manual method, indicating better registrations. Likewise, the automatic method showed a 57% reduction in standard deviation, implying a more stable technique. The algorithm is able to recover the transformation even when data are missing from the top or bottom of the volume.We present a fully automatic registration method to map volumetric data into stereotaxic space that yields results comparable with those of manually based techniques. The method requires no manual identification of points or contours and therefore does not suffer the drawbacks involved in user intervention such as reproducibility and interobserver variability.

Characterization and propagation of uncertainty in diffusion‐weighted MR imaging

2003-10-24

Timothy E.J. Behrens , Mark W. Woolrich , Mark Jenkinson +6 more

Abstract A fully probabilistic framework is presented for estimating local probability density functions on parameters of interest in a model of diffusion. This technique is applied to the estimation of … Abstract A fully probabilistic framework is presented for estimating local probability density functions on parameters of interest in a model of diffusion. This technique is applied to the estimation of parameters in the diffusion tensor model, and also to a simple partial volume model of diffusion. In both cases the parameters of interest include parameters defining local fiber direction. A technique is then presented for using these density functions to estimate global connectivity (i.e., the probability of the existence of a connection through the data field, between any two distant points), allowing for the quantification of belief in tractography results. This technique is then applied to the estimation of the cortical connectivity of the human thalamus. The resulting connectivity distributions correspond well with predictions from invasive tracer methods in nonhuman primate. Magn Reson Med 50:1077–1088, 2003. © 2003 Wiley‐Liss, Inc.

In vivo fiber tractography using DT-MRI data

2000-01-01

Peter J. Basser , Sinisa Pajevic , Carlo Pierpaoli +2 more

Fiber tract trajectories in coherently organized brain white matter pathways were computed from in vivo diffusion tensor magnetic resonance imaging (DT-MRI) data. First, a continuous diffusion tensor field is constructed … Fiber tract trajectories in coherently organized brain white matter pathways were computed from in vivo diffusion tensor magnetic resonance imaging (DT-MRI) data. First, a continuous diffusion tensor field is constructed from this discrete, noisy, measured DT-MRI data. Then a Frenet equation, describing the evolution of a fiber tract, was solved. This approach was validated using synthesized, noisy DT-MRI data. Corpus callosum and pyramidal tract trajectories were constructed and found to be consistent with known anatomy. The method's reliability, however, degrades where the distribution of fiber tract directions is nonuniform. Moreover, background noise in diffusion-weighted MRIs can cause a computed trajectory to hop from tract to tract. Still, this method can provide quantitative information with which to visualize and study connectivity and continuity of neural pathways in the central and peripheral nervous systems in vivo, and holds promise for elucidating architectural features in other fibrous tissues and ordered media.

Three-dimensional tracking of axonal projections in the brain by magnetic resonance imaging

1999-02-01

Susumu Mori , Barbara J. Crain , V. P. Chacko +1 more

The relationship between brain structure and complex behavior is governed by large-scale neurocognitive networks. The availability of a noninvasive technique that can visualize the neuronal projections connecting the functional centers … The relationship between brain structure and complex behavior is governed by large-scale neurocognitive networks. The availability of a noninvasive technique that can visualize the neuronal projections connecting the functional centers should therefore provide new keys to the understanding of brain function. By using high-resolution three-dimensional diffusion magnetic resonance imaging and a newly designed tracking approach, we show that neuronal pathways in the rat brain can be probed in situ. The results are validated through comparison with known anatomical locations of such fibers. Ann Neurol 1999;45:265–269

Stereotaxic white matter atlas based on diffusion tensor imaging in an ICBM template

2008-02-07

Susumu Mori , Kenichi Oishi , Hangyi Jiang +7 more

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Tract-based spatial statistics: Voxelwise analysis of multi-subject diffusion data

2006-04-20

Stephen M. Smith , Mark Jenkinson , Heidi Johansen‐Berg +7 more

Brain development during childhood and adolescence: a longitudinal MRI study

1999-10-01

Jay N. Giedd , Jonathan D. Blumenthal , Neal Jeffries +6 more

Brain development in children and adolescents: Insights from anatomical magnetic resonance imaging

2006-01-01

Rhoshel Lenroot , Jay N. Giedd

Hessian eigenmaps: Locally linear embedding techniques for high-dimensional data

2003-04-30

David L. Donoho , Carrie Grimes

We describe a method for recovering the underlying parametrization of scattered data ( m i ) lying on a manifold M embedded in high-dimensional Euclidean space. The method, Hessian-based locally … We describe a method for recovering the underlying parametrization of scattered data ( m i ) lying on a manifold M embedded in high-dimensional Euclidean space. The method, Hessian-based locally linear embedding, derives from a conceptual framework of local isometry in which the manifold M , viewed as a Riemannian submanifold of the ambient Euclidean space ℝ n , is locally isometric to an open, connected subset Θ of Euclidean space ℝ d . Because Θ does not have to be convex, this framework is able to handle a significantly wider class of situations than the original ISOMAP algorithm. The theoretical framework revolves around a quadratic form ℋ( f ) = ∫ M ∥ H f ( m )∥ \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} \begin{equation*}{\mathrm{_{{\mathit{F}}}^{2}}}\end{equation*}\end{document} dm defined on functions f : M ↦ ℝ. Here Hf denotes the Hessian of f , and ℋ( f ) averages the Frobenius norm of the Hessian over M . To define the Hessian, we use orthogonal coordinates on the tangent planes of M . The key observation is that, if M truly is locally isometric to an open, connected subset of ℝ d , then ℋ( f ) has a ( d + 1)-dimensional null space consisting of the constant functions and a d -dimensional space of functions spanned by the original isometric coordinates. Hence, the isometric coordinates can be recovered up to a linear isometry. Our method may be viewed as a modification of locally linear embedding and our theoretical framework as a modification of the Laplacian eigenmaps framework, where we substitute a quadratic form based on the Hessian in place of one based on the Laplacian.

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Toward a quantitative assessment of diffusion anisotropy

1996-12-01

Carlo Pierpaoli , Peter J. Basser

Abstract Indices of diffusion anisotropy calculated from diffusion coefficients acquired in two or three perpendicular directions are rotationally variant. In living monkey brain, these indices severely underestimate the degree of … Abstract Indices of diffusion anisotropy calculated from diffusion coefficients acquired in two or three perpendicular directions are rotationally variant. In living monkey brain, these indices severely underestimate the degree of diffusion anisotropy. New indices calculated from the entire diffusion tensor are rotationally invariant (RI). They show that anisotropy is highly variable in different white matter regions depending on the degree of coherence of fiber tract directions. In structures with a regular, parallel fiber arrangement, water diffusivity in the direction parallel to the fibers (D | ≈ 1400–1800 × 10 −6 mm 2 /s) is almost 10 times higher than the average diffusivity in directions perpendicular to them ((D + D⊥′)/2 ≈ 150–300 × 10 −6 mm 2 /s), and is almost three times higher than previously reported. In structures where the fiber pattern is less coherent (e.g., where fiber bundles merge), diffusion anisotropy is significantly reduced. However, RI anisotropy indices are still susceptible to noise contamination. Monte Carlo simulations show that these indices are statistically biased, particularly those requiring sorting of the eigenvalues of the diffusion tensor based on their magnitude. A new intervoxel anisotropy index is proposed that locally averages inner products between diffusion tensors in neighboring voxels. This “lattice” RI index has an acceptably low error variance and is less susceptible to bias than any other RI anisotropy index proposed to date.

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Tracking neuronal fiber pathways in the living human brain

1999-08-31

Thomas E. Conturo , Nicolás Lori , Thomas S. Cull +6 more

Functional imaging with positron emission tomography and functional MRI has revolutionized studies of the human brain. Understanding the organization of brain systems, especially those used for cognition, remains limited, however, … Functional imaging with positron emission tomography and functional MRI has revolutionized studies of the human brain. Understanding the organization of brain systems, especially those used for cognition, remains limited, however, because no methods currently exist for noninvasive tracking of neuronal connections between functional regions [Crick, F. & Jones, E. (1993) Nature (London) 361, 109–110]. Detailed connectivities have been studied in animals through invasive tracer techniques, but these invasive studies cannot be done in humans, and animal results cannot always be extrapolated to human systems. We have developed noninvasive neuronal fiber tracking for use in living humans, utilizing the unique ability of MRI to characterize water diffusion. We reconstructed fiber trajectories throughout the brain by tracking the direction of fastest diffusion (the fiber direction) from a grid of seed points, and then selected tracks that join anatomically or functionally (functional MRI) defined regions. We demonstrate diffusion tracking of fiber bundles in a variety of white matter classes with examples in the corpus callosum, geniculo-calcarine, and subcortical association pathways. Tracks covered long distances, navigated through divergences and tight curves, and manifested topological separations in the geniculo-calcarine tract consistent with tracer studies in animals and retinotopy studies in humans. Additionally, previously undescribed topologies were revealed in the other pathways. This approach enhances the power of modern imaging by enabling study of fiber connections among anatomically and functionally defined brain regions in individual human subjects.

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Measurement and classification of psychiatric symptoms

1975-04-01

David Goldberg

MRtrix3: A fast, flexible and open software framework for medical image processing and visualisation

2019-08-29

Jacques‐Donald Tournier , Robert E. Smith , David Raffelt +7 more

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FSL

2011-09-16

Mark Jenkinson , Christian F. Beckmann , Timothy E.J. Behrens +2 more

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Co-planar stereotaxic atlas of the human brain : 3-dimensional proportional system : an approach to cerebral imaging

1988-01-01

J Talairach , P Tournoux , Mark Rayport

Direct and Indirect Radiologic Localization Reference System: Basal Brain Line CA-CP Cerebral Structures in Three-Dimensional Space Practical Examples for the Use of the Atlas in Neuroradiologic Examinations Three-Dimensional Atlas of … Direct and Indirect Radiologic Localization Reference System: Basal Brain Line CA-CP Cerebral Structures in Three-Dimensional Space Practical Examples for the Use of the Atlas in Neuroradiologic Examinations Three-Dimensional Atlas of a Human Brain Nomenclature-Abbreviations Anatomic Index Conclusions.

Disruption of functional and structural topological organization in specific subnetwork among patients with classical trigeminal neuralgia: a graph theory-based magnetic resonance imaging study

2025-06-24

Lan Huang , Meng Li , Yuying Chen +3 more | Brain Imaging and Behavior

Reply to: ‘<scp>MASLD</scp>‐Brain Aging Study Biases: Distribution Shift and Self‐Cancellation’

2025-06-23

Jiao Wang , Huijie Huang , Rongrong Yang +1 more | Liver International

MRI-based insights into brain structural and functional alterations in schizophrenia treated with risperidone

2025-06-20

Hangyu Li , Xinyue Chen , Sen Peng +4 more | Frontiers in Psychiatry

Background Schizophrenia (SZ) is a severe psychiatric disorder, with antipsychotics serving as the primary treatment. Among them, risperidone plays a crucial role in alleviating both positive and negative symptoms while … Background Schizophrenia (SZ) is a severe psychiatric disorder, with antipsychotics serving as the primary treatment. Among them, risperidone plays a crucial role in alleviating both positive and negative symptoms while also enhancing cognitive function. Advances in magnetic resonance imaging (MRI) technology have provided an effective means of investigating the effects of risperidone on the brain, particularly in terms of neural pathways, therapeutic efficacy, and predictive outcomes. This review offers a summary of current findings on the impact of risperidone treatment on gray matter, white matter, and functional brain activity and connectivity in SZ patients, including its neural mechanisms, therapeutic benefits, and potential side effects. Methods Literatures on the use of risperidone for treating schizophrenia were searched in PubMed, Embase and Web of Science analyzing and summarizing the alterations in brain structure and function associated with risperidone. Results Through the analysis and summary, it was found that risperidone treatment in SZ patients can have a marked effect on different structural and functional regions including the prefrontal lobe, temporal lobe, cingulate gyrus, corona radiata, basal ganglia, and corpus callosum. Conclusion Most research has focused on short-term effects, with limited longitudinal data to assess long-term efficacy and side effects, more researches could be added in the future. In addition, more potential methods such as DKI, DSI and brain covariance network have the opportunity to be used in the study of brain structure and function in the treatment of schizophrenia with risperidone in the future.

Anisotropy boosting improves ODF-Fingerprinting tractography in edematous brain

2025-06-20

Patryk Filipiak , Kamri Clarke , Timothy M. Shepherd +3 more

Abstract Peritumoral vasogenic edema of the brain is a major confounding factor for diffusion MRI tractography. Excessive fluids accumulated in edematous white matter decrease anisotropy of water self-diffusion which affects … Abstract Peritumoral vasogenic edema of the brain is a major confounding factor for diffusion MRI tractography. Excessive fluids accumulated in edematous white matter decrease anisotropy of water self-diffusion which affects tracking algorithms. We address this hurdle with ODF-Fingerprinting (ODF-FP) — a dictionary-based fiber reconstruction algorithm that accommodates variability of neural tissue. By adding a regularization term to the ODF-FP matching formula, we boost diffusion anisotropy to improve white matter fiber identification in edematous regions.

Association of Superficial White Matter Microstructure With Cortical Pathology Deposition Across Early Stages of the AD Continuum

2025-06-19

Shu-Yue Wang , Fan Zhang , Qingze Zeng +7 more | Neurology

β-amyloid (Aβ) and tau, 2 prominent pathologies of Alzheimer disease (AD), originate in cortical regions and primarily affect, and even spread along, the white matter tracts directly connected to these … β-amyloid (Aβ) and tau, 2 prominent pathologies of Alzheimer disease (AD), originate in cortical regions and primarily affect, and even spread along, the white matter tracts directly connected to these cortical regions. Superficial white matter (SWM), containing short-range association connections beneath the cortex, has been affected in mild cognitive impairment and AD, with gaps in understanding the disease's early stages. We perform a detailed investigation of individual SWM connections with cortical pathology deposition and cognition in the early stages of the AD continuum. We enroll participants with Aβ PET, tau PET, diffusion MRI, and cognitive status from the Alzheimer's Disease Neuroimaging Initiative (ADNI) and Harvard Aging Brain Study (HABS). We stratify participants into disease stages following the Aβ/tau (AT) framework. We use diffusion MRI tractography to analyze SWM fiber clusters and assess their microstructure through free-water modeling, identifying significant differences between pathologically staged groups. We investigate associations of diffusion measures in SWM fiber clusters with regional pathology deposition (Aβ- and tau- PET uptake) and cognition. The study includes 150 ADNI participants (mean age 73.6 years, 61.3% female) and 175 HABS participants (mean age 75.6 years, 61.1% female). We find the following: (1) SWM microstructure differs along the early-stage Alzheimer disease continuum, with primary abnormalities in posterior brain regions; (2) there are significant free-water alterations in cognitively intact but pathology-positive individuals (p < 0.05, false discovery rate [FDR] corrected); (3) associations are identified between free water in SWM connections and proximal pathologic deposition, as well as between free water in several connections and memory function (standardized β coefficient = [-0.297 to -0.352], all p < 0.05, FDR corrected); and (iv) free water of a temporal SWM connection mediates the impact of temporal tau on memory (95% CI = [-0.146 to -0.002], accounts for 15.0% of the total effect). The findings of this study suggest that the propagation of AD pathology and cognitive changes may involve SWM pathways even in the early stages, emphasizing the importance of SWM in developing AD therapies and early interventions.

Challenges and Opportunities in Computational Neurology

2025-06-19

S. Vijayanand , C. Priya | CRC Press eBooks

Scratching Beneath the Cortex

2025-06-19

Mario Tranfa , Tiago Gil Oliveira | Neurology

Unveiling the neural network of freezing of gait in Parkinson's disease: A coordinate-based network study

2025-06-19

Chiara Camastra , Antonio Augimeri , Aldo Quattrone +1 more | Journal of Parkinson s Disease

Background Freezing of gait (FoG) is a debilitating symptom in Parkinson's disease (PD), yet its pathophysiological mechanisms remain poorly understood. Several studies have investigated the FoG neuroimaging correlates, with heterogeneous … Background Freezing of gait (FoG) is a debilitating symptom in Parkinson's disease (PD), yet its pathophysiological mechanisms remain poorly understood. Several studies have investigated the FoG neuroimaging correlates, with heterogeneous results. Objective This study investigated in a large PD cohort whether the disparate neuroimaging findings may converge to a common brain network. Methods T1-weighted MRI scans of 500 PD patients (90 with FoG [PD-FoG] and 410 without FoG [PD-nFoG]) were acquired from the Parkinson's Progression Markers Initiative. A voxel-based morphometry (VBM) analysis was conducted to identify clusters of decreased grey matter (GM) in PD-FoG patients. Subsequently, VBM coordinates of significant clusters were used as seed regions to generate connectivity network maps using a large functional normative connectome, and these maps were overlapped to identify regions connected with most VBM clusters. Results PD-FoG patients showed GM atrophy in cerebellar lobes, hippocampus, putamen, insula, inferior temporal gyrus and lateral orbitofrontal gyrus compared with PD-nFoG patients. Network analysis revealed that these regions colocalized within a specific brain network focused on midbrain, substantia nigra, subthalamic nucleus, globus pallidus, inferior putamen and dorsal medial cerebellum. These findings were confirmed by using coordinates from previous VBM studies for the network analysis, validating our results. Conclusions This study revealed a brain network underlying FoG in PD, reducing the heterogeneity of previous neuroimaging evidence on FoG. These results may represent a significant step forward in the understanding of FoG and may be relevant for optimized targeted neuro-modulatory treatments to reduce FoG in PD patients.

Harmonizing network-based statistics across different atlases in brain connectome analysis

2025-06-19

Qingyuan Liu , Yongbin Wei , Dongxu Liu +6 more | Communications Biology

Incorporating summary statistics across neuroimaging studies is important for enhancing translatability but poses challenges to connectomic analyses due to diverse methodological pipelines and brain atlases. We present TACOS (Transform brAin … Incorporating summary statistics across neuroimaging studies is important for enhancing translatability but poses challenges to connectomic analyses due to diverse methodological pipelines and brain atlases. We present TACOS (Transform brAin COnnectomes across atlaSes), a novel tool that translates network-based statistics across different atlases without requiring individual raw data. TACOS employs linear models based on anatomical information from brain parcellations and white matter fibers. Testing across 17 atlases, we show TACOS-transformed t-statistics to correlate well to the ground truth for both structural (r = 0.32-0.95) and functional networks (r = 0.57-0.95) using HCP surrogate statistics. These correlations remain consistent when tested with independent data from populations of different ancestries. Furthermore, TACOS effectively harmonizes connectomic results across multi-site schizophrenia data cohorts (r = 0.57-0.94 and 0.75-0.95 for structural and functional networks, respectively). This tool enables cross-atlas transformations of network-based statistics, showing great potential for downstream applications that share and combine multi-site connectomic data.

Diffusion Tensor Imaging Findings in Cerebral Sensorimotor Areas in Patients After Spinal Cord Injury Correlate With Neurophysiological Deficits

2025-06-19

Anna Zimny , Przemysław Podgórski , Weronika Machaj +4 more | Neurorehabilitation and neural repair

Objectives Assessment of sensorimotor cortex and tracts degeneration using novel diffusion tensor imaging (DTI) templates in patients with chronic spinal cord injury (SCI) and its correlation with clinical and neurophysiological … Objectives Assessment of sensorimotor cortex and tracts degeneration using novel diffusion tensor imaging (DTI) templates in patients with chronic spinal cord injury (SCI) and its correlation with clinical and neurophysiological findings. Methods Sex and age-matched 29 patients with chronic SCI (paraplegic: p-SCI; tetraplegic: t-SCI) and 29 healthy controls underwent neurophysiological assessment including motor evoked potentials (MEP). DTI was performed on 3 T magnetic resonance imaging scanner and postprocessed using Human Motor Area and Sensorimotor Area Tract Templates. DTI parameters were compared using analysis of covariance with post hoc Scheffé and Bonferroni corrections. Spearman’s rank test was used for correlations with P < .05 considered significant. Results Compared to controls, all SCI patients showed significantly lower fractional anisotropy (FA) in several tracts (primary motor [M1], somatosensory [S1], pre-supplementary motor area [preSMA], and dorsal premotor [PMd]) and cortices (M1, pre-SMA, and S1). There were no differences in DTI parameters between p-SCI and t-SCI or p-SCI and controls. Compared to controls, t-SCI showed significantly decreased FA within M1 and S1 tracts. In t-SCI higher motor scores were associated with higher FA from ventral premotor area (PMv) tracts and cortex; higher sensory scores were associated with higher FA from S1 tracts. Positive correlations were found between MEP amplitudes from rectus femoris muscles and FA for M1, PMd, PMv, pre-SMA, SMA tracts, and PMv cortex. Conclusions DTI shows remote degeneration of sensorimotor cortex and supraspinal tracts in SCI correlating with several clinical motor and sensory scores, and MEP parameters. DTI metrics have the potential to become biomarkers of remote degeneration.

White matter abnormalities of the frontal–striatal–thalamic circuit in individuals with attenuated positive symptom syndromes: a probabilistic tractography study

2025-06-18

Zhenzhu Chen , Qijing Bo , Lei Zhao +6 more | Schizophrenia

Attenuated positive symptoms syndrome (APSS) is a risk state preceding psychosis, and its early identification is key to early intervention. Previous studies have suggested that disturbances in the frontal-striatal-thalamic (FST) … Attenuated positive symptoms syndrome (APSS) is a risk state preceding psychosis, and its early identification is key to early intervention. Previous studies have suggested that disturbances in the frontal-striatal-thalamic (FST) circuit may play a role in the neuropathology of APSS. However, the evidence regarding white matter structure remains fragmented. This study aimed to systematically investigate white matter (WM) alterations within the FST circuits in individuals with APSS. Diffusion magnetic resonance imaging (dMRI) and T1-weighted images were acquired from 43 individuals with APSS and 50 healthy controls (HCs). The dMRI data were preprocessed using FMRIB Software Library software. The Brainnetome Atlas was utilized to extract regions of interest (ROIs) in the frontal lobe, striatum, and thalamus. Bidirectional probabilistic tractography was performed to construct the FST circuit. The connection probability (CP) and diffusion index values were compared between the APSS and HC groups using the two-sample t test. Compared to HCs, individuals with APSS exhibited significantly lower CP values in right orbital gyrus_area 13- right nucleus accumbens (OrG_A13-NAC) fiber tract; higher mean diffusivity values in the left OrG_A13-NAC and left ventral caudate-left caudal temporal thalamus (vCa-cTtha) fiber tracts; higher radial diffusivity values in the right OrG_A13-NAC fiber tract; and higher axial diffusivity values in multiple frontal lobe ROI-striatum ROI and striatum ROI-thalamus ROI fiber tracts. Overall, individuals with APSS demonstrated white matter microstructural abnormalities, especially in the OrG_A13-NAC fiber tracts. These alterations may contribute to our understanding on the neuropathology of APSS.

Brain white matter development in 8-year-old children is associated with maternal mental health during pregnancy

2025-06-18

Yali Huang , Timothy R. Koscik , Aline Andres +4 more | Frontiers in Human Neuroscience

Background Maternal mental health during pregnancy can influence fetal brain development, yet its long-term effects remain unclear. This study investigates the association between prenatal maternal depression and anxiety symptoms and … Background Maternal mental health during pregnancy can influence fetal brain development, yet its long-term effects remain unclear. This study investigates the association between prenatal maternal depression and anxiety symptoms and white matter microstructure in the limbic system of 8-year-old children. Methods Fifty-one healthy pregnant women and typically developing 8-year-old children dyads were included in this prospective and longitudinal study. Maternal depression and anxiety symptoms were assessed at 12, 24, and 36 weeks of gestation using the Beck Depression Inventory-II (BDI-II) and State–Trait Anxiety Inventory (STAI). Their children underwent a brain MRI examination at age 8 years with multi-shell diffusion imaging analyzed using diffusion tensor imaging (DTI), diffusional kurtosis imaging (DKI), and neurite orientation dispersion and density imaging (NODDI) models for a multi-aspect evaluation of microstructural development. Key diffusion metrics (FA: fractional anisotropy; MD: mean diffusivity; AD: axial diffusivity; RD: radial diffusivity; MK: mean kurtosis; AK: axial kurtosis; RK: radial kurtosis; NDI: neurite density index; ODI: orientation dispersion index; FWF: free water fraction) were extracted from the limbic system white matter structures including cingulum, fornix, and uncinate fasciculus, which are closely associated with emotional and motivational processes. Results Higher maternal depression symptom scores were associated with lower FA ( R = –0.3126, p = 0.0305, in CGH.R; R = –0.3025, p = 0.0366, in FXC.R) and MK ( R = –0.3284, p = 0.0227, in CGG.R) and higher MD ( R = 0.2879, p = 0.0472, in CGH.R) and RD ( R = 0.3451, p = 0.0163, in CGH.R; R = 0.3456, p = 0.0161, in FXC.R) in predominately right-hemisphere limbic tracts. Higher maternal anxiety symptom scores were associated with increased MD ( R = 0.2897, p = 0.0458, in FXC.L; R = 0.2859, p = 0.0488, in UF.L) and RD ( R = 0.3168, p = 0.0283, in FXC.L), decreased NDI ( R = –0.3787, p = 0.0079, in FXC.L; R = –0.3422, p = 0.0173, in UF.R), and increased AK ( R = 0.3154, p = 0.029, in UF.L) in predominately left-hemisphere limbic tracts. Conclusion Our findings suggest that maternal depression and anxiety during pregnancy may have long-lasting impacts on offspring white matter microstructure maturation in the limbic system. This highlights the need for prenatal mental health screening and potential interventions to promote brain development and support optimal neurodevelopmental outcomes in children.

Learning topological states from randomized measurements using variational tensor network tomography

2025-06-18

NULL AUTHOR_ID | PRX Quantum

Amino acid patterns predict white matter integrity measures in the brain in patients across the Alzheimer’s disease continuum

2025-06-18

Farshad Goharmanesh , Maryam Masmoie , Hamideh Nasiri +7 more | Metabolic Brain Disease

High‐density MRI coil arrays with integrated field monitoring systems for human connectome mapping

2025-06-18

Mirsad Mahmutović , M Shrestha , Gabriel Ramos‐Llordén +7 more | Magnetic Resonance in Medicine

ABSTRACT Purpose To develop and test two high‐density MRI coil arrays with integrated field monitoring systems for enhanced diffusion imaging with strong diffusion‐sensitizing gradients. Methods Two multichannel head coils were … ABSTRACT Purpose To develop and test two high‐density MRI coil arrays with integrated field monitoring systems for enhanced diffusion imaging with strong diffusion‐sensitizing gradients. Methods Two multichannel head coils were constructed for first‐ and second‐generation 3T Connectome MRI scanners, incorporating 64 and 72 receive channels, respectively. The array coils were evaluated using RF bench‐level metrics, including quality factor, tuning, matching, and coupling measurements. Imaging performance was comprehensively assessed through metrics such as SNR, efficiency, and inter‐channel noise correlations, and compared with and without field camera integration. Parallel imaging capability was evaluated using geometry (g)‐factors. The field camera performance was characterized by quantifying phase errors and field probe FID lifetimes. In vivo DWI acquisitions with high ‐values were performed to evaluate the system's ability to correct higher‐order field perturbations. Results The developed arrays demonstrated up to 1.4‐fold higher SNR and superior g‐factor performance when compared to a commercially available 32‐channel head coil. Integration of the field camera was achieved without compromising the performance of either system. In vivo imaging with concurrent field monitoring enabled accurate spatiotemporal field corrections, significantly reducing geometric distortions, blurring, and ghosting in high ‐value DWI. Conclusion The integration of high‐density MRI arrays with field monitoring systems facilitated the capture and correction of spatiotemporal field perturbations during strong gradient activity, substantially enhancing image quality and diffusion parameter mapping quality. These advancements provide a robust platform for exploring the structural intricacies of the human connectome.

Anatomo-functional approach to multimodal motor mapping in diffuse glioma surgery: hierarchical networks

2025-06-17

José Pedro Lavrador , Víctor Expósito García , Francesco Marchi +7 more | Brain Structure and Function

The use of intraoperative tractography in brain tumor and epilepsy surgery: a systematic review and meta-analysis

2025-06-17

Holly Aylmore , Fiona Young , Kristian Aquilina +2 more | Frontiers in Neuroimaging

Introduction Tractography is the only available technique for visualizing whitematter pathways within the living brain. Avoiding these pathways during surgical interventions for brain tumors and epilepsy is key to reducing … Introduction Tractography is the only available technique for visualizing whitematter pathways within the living brain. Avoiding these pathways during surgical interventions for brain tumors and epilepsy is key to reducing postoperative neurological deficits whilst achieving maximum safe resection. Despite this, the use of intraoperative tractography is not widely adopted in clinical practice, with time required to run analyses often cited as a limitation. This systematic review and meta-analysis aimed to assess the impact of intraoperative tractography on neurosurgical outcomes in both tumor and epilepsy surgeries. Methods Conducted in accordance with PRISMA guidelines, five major databases were searched using neurosurgery, tractography, brain tumor, and epilepsy terms. Original primary research studies in English were included. A risk of bias analysis was conducted using the MINORS tool. Results The search strategy identified 2,611 papers. Following de-duplication and screening, 26 papers were included in the final analysis. Risk of bias was found to be moderate. Findings suggest that the use of intraoperative tractography has the potential to improve surgical outcomes for patients undergoing tumor and epilepsy surgery. Meta-analysis indicated a good rate of gross total resection, 79%, and only three studies of brain tumors and one study of epilepsy reported worsening of neurological deficits. Discussion Though the evidence supporting its use remains limited, results indicate that intraoperative tractography can be a valuable tool in improving neurosurgical outcomes and reducing the risk of postoperative deficits. Further research is required to determine optimal use in clinical practice. Systematic review registration https://www.crd.york.ac.uk/PROSPERO/view/CRD42023427427 , Identifier: CRD42023427427.

Structural connector hub properties of the thalamus in large-scale brain networks: white matter structure as an anatomical basis

2025-06-17

Tatsuya Jitsuishi , Atsushi Yamaguchi | NeuroImage

Connector hubs are critical to maintain the modular architecture of large-scale brain networks. This study aimed to explore the structural connector hub properties of the thalamus via the white matter … Connector hubs are critical to maintain the modular architecture of large-scale brain networks. This study aimed to explore the structural connector hub properties of the thalamus via the white matter pathways as an anatomical substrate. First, whole-brain tractography was performed to examine the thalamocortical structural connectivity (SC) based on the canonical seven resting-state networks (7-RSNs). It identified multiple overlapping clusters in the thalamus, which are highly connected to the canonical 7-RSNs. Graph theoretical analysis indicated that these clusters have higher participation coefficient (PC) and within-module degree Z-score (WMD) values, suggesting nodal centrality between separate modules. Further, thalamic nuclei with structurally defined connector hub properties showed high functional connectivity (FC) with canonical RSNs in multiple task-fMRI analyses. Collectively, these findings suggest that the thalamus harbors intrinsic structural connector hub properties in large-scale networks as an anatomical basis.

Multiscale characterization of myelin distribution with polarized THG microscopy

2025-06-17

Joséphine Morizet , Nicolas Olivier , Marie‐Stéphane Aigrot +6 more | Optica

Robust functional ultrasound imaging in the awake and behaving brain: a systematic framework for motion artifact removal

2025-06-17

Samuel Diebolt , Felipe Cybis Pereira , Jean-Charles Mariani +6 more | bioRxiv (Cold Spring Harbor Laboratory)

Abstract Functional ultrasound imaging (fUSI) is a promising tool for studying brain activity in awake and behaving animals, offering insights into neural dynamics that are more naturalistic than those obtained … Abstract Functional ultrasound imaging (fUSI) is a promising tool for studying brain activity in awake and behaving animals, offering insights into neural dynamics that are more naturalistic than those obtained under anesthesia. However, motion artifacts pose a significant challenge, introducing biases that can compromise the integrity of the data. This study provides a comprehensive evaluation and benchmarking of strategies for detecting and removing motion artifacts in transcranial fUSI acquisitions of awake mice. We evaluated 792 denoising strategies across four datasets, focusing on clutter filtering, scrubbing, frequency filtering, and confound regression methods. Our findings highlight the superior performance of adaptive clutter filtering and aCompCor confound regression in mitigating motion artifacts while preserving functional connectivity patterns. We also demonstrate that high-pass filtering is generally more effective than band-pass filtering in the presence of motion artifacts. Additionally, we show that with effective clutter filtering, scrubbing may become optional, which is particularly beneficial for experimental designs where motion correlates with conditions of interest. Based on these insights, we propose four optimized denoising paradigms tailored to different experimental constraints, providing practical recommendations for enhancing the reliability and reproducibility of fUSI data. Our findings challenge current practices in the field and have immediate practical implications for existing fUSI analysis workflows, paving the way for more sophisticated applications of fUSI in studying complex brain functions and dysfunctions in awake experimental paradigms.

Think deep in the tractography game: deep learning for tractography computing and analysis

2025-06-16

Fan Zhang , Antoine Théberge , Pierre‐Marc Jodoin +2 more | Brain Structure and Function

The tractographer’s dilemma: understanding sources of variability in tractography

2025-06-16

Flavio Dell’Acqua , Alexander Leemans , Fan Zhang +3 more | Brain Structure and Function

Fixel-Based Analysis Reveals Detailed White Matter Changes in Semantic Dementia

2025-06-16

Maria Luisa Mandelli , Yann Cobigo , Ilaria Perretti +7 more | Research Square (Research Square)

<title>Abstract</title> Background and Purpose Accurately characterizing white matter (WM) microstructure is critical for understanding neurodegenerative diseases such as semantic dementia (SD). Regionally constrained techniques like tract-based spatial statistics (TBSS) rely … <title>Abstract</title> Background and Purpose Accurately characterizing white matter (WM) microstructure is critical for understanding neurodegenerative diseases such as semantic dementia (SD). Regionally constrained techniques like tract-based spatial statistics (TBSS) rely on diffusion-tensor imaging (DTI) and assume a single fiber population per voxel, limiting their sensitivity to complex architecture. Fixel-based morphometry (FBM) overcomes this by assessing multiple fiber populations (fixels) within a single voxel. In this study, we compared TBSS and Fixel-based analysis (FBA) for detecting WM alterations in SD variants associated with anterior temporal lobe (ATL) atrophy. Methods Multi-shell diffusion MRI from 16 left-lateralized semantic-variant PPA (svPPA) and 15 right-lateralized semantic-behavioral fronto-temporal dementia (sbvFTD) cases, plus 44 neurologically healthy controls, underwent both TBSS-DTI and whole-brain FBA. Fiber-specific metrics of fiber density and cross-section were contrasted with conventional DTI measures. Results Both methods confirmed damage to ATL-connected tracts—the uncinate fasciculus, inferior longitudinal fasciculus, inferior fronto-occipital fasciculus, and temporal projections of the arcuate fasciculus. FBA, however, revealed additional involvement of juxtacortical and other previously overlooked pathways, including the tapetum and anterior commissure, projections to the parahippocampal gyrus and amygdala, and longer-range parietal connections. Conclusions By capturing fiber-specific micro- and macrostructural changes, FBA yields a more comprehensive map of WM degeneration in SD than TBSS. The ability to detect early alterations in commissural and mesial-temporal pathways refines our understanding of disease spread and highlights candidate targets for monitoring and intervention aimed at preserving cognitive function.

Structural White Matter Correlates of the Crowding Effect: Insights From a Tractography Study of the Arcuate Fasciculus Post‐Hemispherotomy

2025-06-15

Justus Bisten , Johannes Grün , Christian Hoppe +7 more | Human Brain Mapping

ABSTRACT The neuropsychological crowding effect denotes the reallocation of cognitive functions within the contralesional hemisphere following unilateral brain damage, prioritizing language at the expense of nonverbal abilities. This study investigates … ABSTRACT The neuropsychological crowding effect denotes the reallocation of cognitive functions within the contralesional hemisphere following unilateral brain damage, prioritizing language at the expense of nonverbal abilities. This study investigates structural white matter correlates of crowding in the arcuate fasciculus (AF), a key language tract, using hemispherotomy as a unique setting to explore structural reorganization supporting language preservation. We explore two main hypotheses. First, the contralesional right AF undergoes white matter reorganization correlated with preserved language function at the expense of nonverbal abilities following left‐hemispheric damage. Second, this reorganization varies with epilepsy etiology, influencing different stages of developmental language lateralization. This retrospective study included individuals post‐hemispherotomy and healthy controls. Inclusion criteria were; (1) being a native German speaker, (2) having no MRI contraindication, (3) the ability to undergo approximately 2 h of MRI scans, and (4) the ability to participate in neuropsychological assessments over two consecutive days. Neuroimaging included T1‐, T2‐, and diffusion‐weighted imaging, alongside postoperative neuropsychological assessments, where it was taken as evidence for crowding if verbal IQ exceeded performance IQ by at least 10 points. The AF was reconstructed using advanced tractography, and CoBundleMAP was used to compare morphologically corresponding AF subsections. Statistical significance was set at , with correction for multiple comparisons applied across contiguous tract sections using Threshold‐Free Cluster Enhancement. The final cohort comprised 22 individuals post‐hemispherotomy (median age: years, range: ; 55% female; 55% with left‐sided surgeries) and 20 healthy controls (median age: years, range: ; 55% female). Crowding was associated with significantly higher fractional anisotropy (FA) in the AF (, Cohen's ), but only observed in individuals with left‐sided hemispherotomy, localized to a subsection between Geschwind's territory and Wernicke's area (). This region also displayed significantly higher normalized FA in AF of individuals with congenital etiology and crowding compared to acquired etiology and no crowding (). This study identifies previously unreported neural correlates of crowding in right contralesional AF of individuals post‐hemispherotomy and highlights specific AF subsections involved in preserving language functions at the cost of nonverbal abilities. The findings suggest a link between crowding and epilepsy etiology, particularly in the region spanning Geschwind's territory and Wernicke's area.

Repairing Myelin After Irradiated Pediatric Brain Tumor: A Magnetization Transfer Imaging Analysis

2025-06-14

Éloïse Baudou , Jennifer Ryan , Julie Tseng +5 more | Pediatric Blood & Cancer

ABSTRACT Background While exercise training and metformin treatment have demonstrated preliminary cognitive improvements in pediatric brain tumor (PBT) survivors, the neuronal mechanisms underlying their cognitive improvements are unclear. Diffusion‐weighted metrics … ABSTRACT Background While exercise training and metformin treatment have demonstrated preliminary cognitive improvements in pediatric brain tumor (PBT) survivors, the neuronal mechanisms underlying their cognitive improvements are unclear. Diffusion‐weighted metrics (e.g., fractional anisotropy [FA]) are commonly used to evaluate remyelination, but magnetization transfer imaging is thought to be more sensitive to myelin plasticity. Methods We compared white matter changes after exercise and metformin interventions by evaluating magnetization transfer ratio (MTR) and FA changes in irradiated PBT survivors who completed either an exercise (NCT01944761) or metformin pilot trial (NCT02040376) (30 participants: exercise n = 11, metformin n = 12, and control n = 7). Then, we explored correlations between MTR and cognitive outcomes. Results There were significant MTR changes in three brain regions (right forceps minor in both interventions, right inferior and superior longitudinal fasciculi in the exercise group), but no significant FA changes. MTR increases occurred in the right forceps minor in the exercise and metformin groups compared with the control group ( p < 0.033), and in the superior longitudinal fasciculus in the exercise group compared with the control group ( p = 0.016). Preliminary correlations between MTR and cognitive changes were not significant after correcting for multiple comparisons. Conclusions Our results suggest that 12 weeks of exercise or metformin intervention may promote remyelination in PBT survivors in brain regions involved in memory and executive function, and there may be differences in the brain regions affected by each intervention. This work sets the stage for larger clinical trials to identify definitive differences in MTR and validate their association with cognition.

Short association fiber tractography: key insights and surprising facts

2025-06-14

Kurt G. Schilling , Fan Zhang , Claudio Román +2 more | Brain Structure and Function

ADVANCED NEUROLOGICAL IMAGING ANALYSIS USING DIFFUSION TENSOR TECHNIQUES AND DISTRIBUTED WEB SYSTEMS

2025-06-14

DAN CACOVEAN , Marian Ileana | REVUE ROUMAINE DES SCIENCES TECHNIQUES — SÉRIE ÉLECTROTECHNIQUE ET ÉNERGÉTIQUE

Diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI) are crucial in modern neurological diagnostics, enabling detailed analysis of brain structures and connectivity. This article presents a comprehensive approach to analysing … Diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI) are crucial in modern neurological diagnostics, enabling detailed analysis of brain structures and connectivity. This article presents a comprehensive approach to analysing MRI images using advanced tools such as the FSL software library. The proposed method leverages distributed web systems to enhance the scalability and accessibility of image processing and analysis across multiple medical facilities. Key steps, including noise reduction, artefact removal, and tensor reconstruction, are performed to improve diagnostic accuracy. Additionally, metrics such as fractional anisotropy (FA), mean diffusivity (MD), and axial diffusivity (AD) are evaluated to detect microstructural brain abnormalities. The integration of distributed web technologies facilitates real-time collaboration between specialists, accelerating diagnostic processes and enabling cross-hospital data sharing. This study highlights the potential of combining cutting-edge imaging techniques with scalable digital infrastructures to optimise medical decision-making and improve patient outcomes.

Lesion distribution and network mapping in dyskinetic cerebral palsy

2025-06-13

Ana Luísa de Almeida Marcelino , Bassam Al‐Fatly , Mehmet Salih Tuncer +3 more | Brain Communications

Abstract Dyskinetic cerebral palsy encompasses a group of predominantly perinatally acquired complex motor disorders that present with dystonia and/or choreoathetosis and are frequently associated with brain lesions in neuroimaging. Recently, … Abstract Dyskinetic cerebral palsy encompasses a group of predominantly perinatally acquired complex motor disorders that present with dystonia and/or choreoathetosis and are frequently associated with brain lesions in neuroimaging. Recently, lesion network mapping provided a tool to redefine neurological disorders as circuitopathies. Elucidating the common networks impacted by lesions in this condition could pave the way to identify new targets for neuromodulatory therapeutic approaches. In this study, we aim to assess lesion distribution in dyskinetic cerebral palsy and identify a related functional network derived from lesions. Here, we review the literature of MRI findings in dyskinetic cerebral palsy and perform literature-based lesion network mapping. Articles reporting conventional MRI findings clearly attributable to affected patients were included for review. Imaging findings and their anatomical distribution were extracted and quantified according to an established MRI classification system for cerebral palsy. Reviewed articles were searched for figures depicting lesions and these were traced onto a pediatric template. Whole-brain functional connectivity from lesions causing dyskinetic cerebral palsy was calculated using a pediatric resting-state functional MRI connectome. Individual maps were thresholded and later overlapped to derive a common network map associated with dyskinetic cerebral palsy. Results were contrasted with two control datasets for spatial specificity. Review of 48 selected articles revealed that grey matter injury predominated (51%), followed by white matter injury (28%). In 16% of cases MRI was normal. Subcortical lesions affected the thalamus, pallidum and putamen in &gt;40% of reported patients, respectively. Figures available from 23 literature cases were used to calculate the lesion netwok map of dyskinetic cerebral palsy. The lesion-derived map revealed functional connectivity to a wide network including the brainstem, cerebellum, basal ganglia, cingulate, and sensorimotor cortices. The strongest connectivity was found for the motor thalamus. This study confirms subcortical grey matter lesions as the most common MRI finding in dyskinetic cerebral palsy. The neural network identified with lesion network mapping includes areas previously implicated in hyperkinetic disorders and highlights the motor thalamus as a common network node. These results should be validated and their therapeutic implications explored in prospective trials.

Correcting pulse duration effects in the diffusional kurtosis of the multi‐compartment Kärger model

2025-06-10

Jens H. Jensen | Magnetic Resonance in Medicine

To demonstrate a method of reducing pulse duration effects for the diffusional kurtosis of the multi-compartment Kärger model (KM) as estimated with a Stejskal-Tanner DWI sequence. An effective diffusion time … To demonstrate a method of reducing pulse duration effects for the diffusional kurtosis of the multi-compartment Kärger model (KM) as estimated with a Stejskal-Tanner DWI sequence. An effective diffusion time is introduced that corrects errors in the apparent diffusional kurtosis arising from a nonzero pulse duration δ for the multi-compartment KM. The correction is exact to first order in the diffusion time Δ, and numerical calculations are used to assess how well it reduces pulse duration effects. Specifically, for the two-compartment KM, the deviations of the apparent kurtosis obtained with the Stejskal-Tanner sequence from the exact kurtosis are calculated for the full range of δ and Δ, and similar calculations are performed for the deviation in the derivative of the kurtosis with respect to Δ. For the general multi-compartment KM, upper bounds on the maximum magnitude of the deviations are determined. Application of the correction to estimation of intercompartmental exchange rates is illustrated with several examples. For the two-compartment KM, the correction reduces the deviation of the apparent kurtosis and its time derivative for most values of δ and Δ. For the general multi-compartment KM, the maximum deviation magnitude, relative to the initial kurtosis, is 2.26% for the uncorrected kurtosis and 0.57% after correction. The correction reduces the maximum deviation magnitude of the derivative from 46% to less than 1%. Pulse duration effects for the kurtosis of the multi-compartment KM can be strongly suppressed by applying the effective diffusion time correction.