About
170
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Introduction
Additional affiliations
June 2018 - June 2018
International Society for Magnetic Resonance in Medicine
Position
- Lecturer
Description
- ISMRM 2018 weekend diffusion MRI course
May 2016 - May 2019
Pint of Science
Position
- Invited speaker at Pint of Science Festival
Description
- Invited speaker for 2016 and 2019 editions of Pint of Science Festival
Publications
Publications (170)
Multi-shell multi-tissue constrained spherical deconvolution (MSMT-CSD) and single-shell 3-tissue CSD (SS3T-CSD) decompose the diffusion MRI signal in a white matter (WM) fibre orientation distribution (FOD) and grey matter (GM) and cerebrospinal fluid (CSF) compartments. An unsupervised method was recently proposed to estimate the required WM/GM/C...
To overcome the fact that the fibre orientation distribution (FOD) from constrained spherical deconvolution (CSD) assumes a single-fibre white matter (WM) response function—and is thus inappropriate and distorted in voxels containing grey matter (GM) or cerebrospinal fluid (CSF)—multi-shell multi-tissue CSD (MSMT-CSD) was proposed. MSMT-CSD can res...
Constrained spherical deconvolution (CSD) is a robust approach to resolve the fibre orientation distribution (FOD) from diffusion MRI data. However, the FOD from CSD only aims to represent "pure" white matter (WM) and is inappropriate/distorted in regions of (partial voluming with) grey matter (GM) or cerebrospinal fluid (CSF). Multi-shell multi-ti...
Multi-shell multi-tissue constrained spherical deconvolution (MSMT-CSD) and single-shell 3-tissue CSD (SS3T-CSD) resolve WM fibre orientation distributions and GM and CSF tissue compartments by deconvolving WM, GM and CSF response functions from the diffusion MRI data. We aim for more general interpretation of the “WM/GM/CSF” compartments obtained...
FLAIR MR images feature striking contrast, allowing easy identification of white matter hyperintense lesions. While such lesions have been explained by a range of microstructural characteristics, FLAIR itself doesn't provide specificity to distinguish these heterogeneous origins. 3-tissue CSD techniques resolve white matter (WM), grey matter (GM) a...
Introduction
There is growing evidence suggesting that children with prenatal alcohol exposure (PAE) struggle with cognitively demanding tasks, such as learning, attention, and language. Complex structural network analyses can provide insight into the neurobiological underpinnings of these functions, as they may be sensitive for characterizing the...
Patients with schizophrenia exhibit structural and functional dysconnectivity but the relationship to the well-documented cognitive impairments is less clear. This study investigates associations between structural and functional connectivity and executive functions in antipsychotic-naïve patients experiencing schizophrenia. Sixty-four patients wit...
Background
The effects of low-moderate prenatal alcohol exposure (PAE) on brain development have been infrequently studied.
Aim
To compare cortical and white matter structure between children aged 6 to 8 years with low-moderate PAE in trimester 1 only, low-moderate PAE throughout gestation, or no PAE.
Methods
Women reported quantity and frequency...
Background
Age‐related cognitive decline is linked to changes in the brain, particularly the deterioration of white matter (WM) microstructure that accelerates after the age of 60. WM deterioration is associated with mild cognitive impairment and dementia, but the origin and role of white matter signal abnormalities (WMSA) seen in standard MRI rema...
Early life experiences can exert a significant influence on cortical and cognitive development. Very preterm birth exposes infants to several adverse environmental factors during hospital admission, which affect cortical architecture. However, the subsequent consequence of very preterm birth on cortical growth from infancy to adolescence has never...
The network-based statistic (NBS) is a popular method for performing edge-wise statistical inference on brain networks, with a known limitation in the form of a need for the user to pre-define an arbitrary cluster-forming threshold. Recently a new method, the “Threshold Free Network Based Statistic” (TFNBS), was proposed to attempt to overcome this...
Diffusion magnetic resonance imaging studies often investigate white matter (WM) microstructural degeneration in aging by probing WM regions that exhibit negative age associations of fractional anisotropy (FA). However, WM regions in which FA is unassociated with age are not necessarily "spared" in aging. Besides the confound of inter-participant h...
Aging is associated with changes in the central nervous system and leads to reduced life quality. Here, we investigated the age-related differences in the CNS underlying motor performance deficits using magnetic resonance spectroscopy and diffusion MRI. MRS measured N-acetyl aspartate (NAA), choline (Cho), and creatine (Cr) concentrations in the se...
Fixel-based analysis was used to probe age-related changes in white matter micro- and macrostructure of the corpus callosum between participants with (N = 54) and without (N = 50) autism spectrum disorder (ASD). Data were obtained from the Autism Brain Imaging Data Exchange-II (ABIDE-II). Compared to age-matched controls, young adolescents with ASD...
Multiple lines of research support the dysconnectivity hypothesis of schizophrenia. However, findings on white matter (WM) alterations in patients with schizophrenia are widespread and non-specific. Confounding factors from magnetic resonance image (MRI) processing, clinical diversity, antipsychotic exposure, and substance use may underlie some of...
Background and Objectives
Cerebral white matter health can be estimated by MRI-derived indices of microstructure. White matter dysfunction is increasingly recognized as a contributor to neurodegenerative disorders affecting cognition and to functional outcomes after stroke. Reduced indices of white matter microstructure have been demonstrated cross...
Early life experiences, such as very preterm (VP) birth, can affect brain and cognitive development. Several prior studies investigated brain structure in adults born VP; synthesising these studies may help to provide a clearer understanding of long-term effects of VP birth on the brain. We systematically searched Medline and Embase for articles th...
Infants born very preterm (VPT; ≤29 weeks of gestation) are at high risk of developmental disabilities and abnormalities in neural white matter characteristics. Early physical therapy interventions such as Supporting Play Exploration and Early Development Intervention (SPEEDI2) are associated with improvements in developmental outcomes. Six VPT inf...
We present a dataset of magnetic resonance imaging (MRI) data (T1, diffusion, BOLD) acquired in 25 brain tumor patients before the tumor resection surgery, and six months after the surgery, together with the tumor masks, and in 11 controls (recruited among the patients’ caregivers). The dataset also contains behavioral and emotional scores obtained...
The superior longitudinal fasciculus (SLF) is a complex associative tract comprising three distinct subdivisions in the frontoparietal cortex, each of which has its own anatomical connectivity and functional roles. However, many studies on white matter development, hampered by limitations of data quality and tractography methods, treated the SLF as...
Background
Tensor-based investigations suggest that delayed or disrupted white matter (WM) development may relate to adverse behavioral outcomes in individuals born very preterm (VP), however, metrics derived from such models lack specificity. Here, we applied a fixel-based analysis framework to examine WM microstructural and macrostructural correl...
Aging may be associated with motor decline that is attributed to deteriorating white matter microstructure of the corpus callosum (CC), among other brain-related factors. Similar to motor functioning, executive functioning (EF) typically declines during aging, with age-associated changes in EF likewise being linked to altered white matter connectiv...
Introduction
Neonatal arterial ischemic stroke (NAIS) has been shown to affect white matter (WM) microstructure beyond the lesion. Here, we employed fixel-based analysis, a technique which allows to model and interpret WM alterations in complex arrangements such as crossing fibers, to further characterize the long-term effects of NAIS on the entire...
There have been many studies demonstrating children born very preterm exhibit brain white matter microstructural alterations, which have been related to neurodevelopmental difficulties. These prior studies have often been based on diffusion MRI modelling and analysis techniques, which commonly focussed on white matter microstructural properties in...
Background
Corpus callosum anomalies are commonly noted in autism spectrum disorder (ASD). Given the complexity of its microstructural architecture, with crossing fibers projecting throughout, we applied fixel-based analysis to probe white matter micro- and macrostructure within this region. As ASD is a neurodevelopmental condition with noted abnor...
Functional and anatomical hemispheric asymmetries abound in the neural language system, yet the relationship between them remains elusive. One attractive proposal is that structural interhemispheric differences reflect or even drive functional language laterality. However, studies on structure–function couplings either find that left and right lang...
Recent studies suggest a framework where white matter (WM) atrophy plays an important role in fronto-temporal dementia (FTD) pathophysiology. However, these studies often overlook the fact that WM tracts bridging different brain regions may have different vulnerabilities to the disease and the relative contribution of GM atrophy to this WM model, r...
Objectives
To investigate the timeframe prior to symptom onset when cortico-basal ganglia white matter (white matter) loss begins in premanifest Huntington’s disease (preHD), and which striatal and thalamic sub-region white matter tracts are most vulnerable.
Methods
We performed fixel-based analysis, which allows resolution of crossing white matte...
Background
We aimed to chart white matter integrity over 3 years after stroke, to examine if post‐stroke loss of white matter continues to be accelerated compared to control participants.
Method
We applied a longitudinal “fixel”‐based analysis, sensitive to fibre tract‐specific differences within a voxel, to assess axonal loss in stroke (N=71, 22...
Background
Children born very preterm (VP) are at higher risk of emotional and behavioral problems compared with full-term (FT) children. We investigated the neurobiological basis of internalizing and externalizing symptoms in individuals born VP and FT by applying a graph theory approach.
Methods
Structural and diffusion MRI data were combined to...
The book is available here: https://www.elsevier.com/books/connectomic-deep-brain-stimulation/horn/978-0-12-821861-7
Diffusion MRI is currently the only non-invasive imaging technique that allows us to map the location and trajectory of bundles of white matter axons throughout the brain, in vivo and without ionising radiation. In this chapter, we provide a general intuition as to how microstructural properties of white matter can be derived from measuring self-di...
Diffusion MRI has provided the neuroimaging community with a powerful tool to acquire in-vivo data sensitive to microstructural features of white matter, up to 3 orders of magnitude smaller than typical voxel sizes. The key to extracting such valuable information lies in complex modelling techniques, which form the link between the rich diffusion M...
Supplementary Document 3 for Dhollander, T., Clemente, A., Singh, M., Boonstra, F., Civier, O., Duque, J. D., Egorova, N., Enticott, P., Fuelscher, I., Gajamange, S., Genc, S., Gottlieb, E., Hyde, C., Imms, P., Kelly, C., Kirkovski, M., Kolbe, S., Liang, X., Malhotra, A., Mito, R., Poudel, G., Silk, T.J., Vaughan, D.N., Zanin, J., Raffelt, D., Caey...
Supplementary Document 2 for Dhollander, T., Clemente, A., Singh, M., Boonstra, F., Civier, O., Duque, J. D., Egorova, N., Enticott, P., Fuelscher, I., Gajamange, S., Genc, S., Gottlieb, E., Hyde, C., Imms, P., Kelly, C., Kirkovski, M., Kolbe, S., Liang, X., Malhotra, A., Mito, R., Poudel, G., Silk, T.J., Vaughan, D.N., Zanin, J., Raffelt, D., Caey...
Supplementary Document 4 for Dhollander, T., Clemente, A., Singh, M., Boonstra, F., Civier, O., Duque, J. D., Egorova, N., Enticott, P., Fuelscher, I., Gajamange, S., Genc, S., Gottlieb, E., Hyde, C., Imms, P., Kelly, C., Kirkovski, M., Kolbe, S., Liang, X., Malhotra, A., Mito, R., Poudel, G., Silk, T.J., Vaughan, D.N., Zanin, J., Raffelt, D., Caey...
Supplementary Document 1 for Dhollander, T., Clemente, A., Singh, M., Boonstra, F., Civier, O., Duque, J. D., Egorova, N., Enticott, P., Fuelscher, I., Gajamange, S., Genc, S., Gottlieb, E., Hyde, C., Imms, P., Kelly, C., Kirkovski, M., Kolbe, S., Liang, X., Malhotra, A., Mito, R., Poudel, G., Silk, T.J., Vaughan, D.N., Zanin, J., Raffelt, D., Caey...
Diffusion-weighted magnetic resonance imaging (dMRI) is the primary method for noninvasively studying the organization of white matter in the human brain. Here we introduce QSIPrep, an integrative software platform for the processing of diffusion images that is compatible with nearly all dMRI sampling schemes. Drawing on a diverse set of software s...
Attentional lapses interfere with goal-directed behaviors, which may result in harmless (e.g., not hearing instructions) or severe (e.g., fatal car accident) consequences. Task-related functional MRI (fMRI) studies have shown a link between attentional lapses and activity in the frontoparietal network. Activity in this network is likely to be media...
Multi-tissue constrained spherical deconvolution of diffusion MRI data yields white matter fibre orientation distributions, from which a quantitative metric of apparent fibre density can be obtained. Unlike most other diffusion MRI models, this fibre density metric is directly proportional to the diffusion-weighted signal magnitude, and thus intens...
While many studies have used diffusion MRI to investigate white matter microstructure, fewer studies have investigated cortical grey matter microstructure. We investigated cortical microstructural tissue and fluid composition using diffusion tissue signal fractions from Single-Shell 3-Tissue Constrained Spherical Deconvolution, in a cohort of prete...
We investigated the microstructural composition of the brain tissue in 130 adolescents born very preterm (VP) compared with 45 full-term (FT)-born controls. This involved a novel voxel-based analysis of white matter-like, grey matter-like, and fluid-like (free-water) diffusion tissue signal fractions derived by Single-Shell 3-Tissue Constrained Sph...
Methadone is often used as for medication-assisted treatment of heroin addiction during pregnancy. Children with prenatal exposure to the drug are at increased risk of neurodevelopmental and behavioural impairment. We recently reported that prenatal exposure to methadone is associated with microstructural alterations in major white matter tracts, a...
Processing speed on cognitive tasks relies upon efficient communication between widespread regions of the brain. Recently, novel methods of quantifying network communication like ‘navigation efficiency’ have emerged, which aim to be more biologically plausible compared to traditional shortest path length-based measures. However, it is still unclear...
Objective:
Studies of motor outcome after Neonatal Arterial Ischemic Stroke (NAIS) often rely on lesion mapping using MRI. However, clinical measurements indicate that motor deficit can be different than what would solely be anticipated by the lesion extent and location. Because this may be explained by the cortical disconnections between motor are...
The superior longitudinal fasciculus (SLF) is a complex associative tract comprising of three distinct subdivisions in the fronto-parietal cortex, each presenting different anatomical connectivity and different functional roles. However, the subdivision of SLF was hampered by limitations of data quality and tractography methods, and many studies on...
Objectives
To investigate the timeframe prior to symptom onset when cortico-basal ganglia white matter (WM) loss begins in premanifest Huntington’s disease (preHD), and which striatal and thalamic sub-region WM tracts are most vulnerable.
Methods
We performed fixel-based analysis, which allows resolution of crossing WM fibres at the voxel level, o...
Using advanced diffusion MRI, we aimed to assess the microstructural properties of normal-appearing white matter (NAWM) preceding conversion to white matter hyperintensities (WMHs) using 3-tissue diffusion signal compositions in ischemic stroke. Data were obtained from the Cognition and Neocortical Volume After Stroke (CANVAS) study. Diffusion-weig...
Language is the most commonly described lateralised cognitive function, relying more on the left hemisphere compared to the right hemisphere in over 90% of the population. Most research examining the structure-function relationship of language lateralisation only included people showing a left language hemisphere dominance. In this work, we applied...
The final peer reviewed version of this work was published in NeuroImage. The full text and supplementary documents are available open access via https://doi.org/10.1016/j.neuroimage.2021.118417 — Abstract: Diffusion MRI has provided the neuroimaging community with a powerful tool to acquire in-vivo data sensitive to microstructural features of whi...
In complex everyday environments, action selection is critical for optimal goal-directed behavior. This refers to the process of choosing a proper action from the range of possible alternatives. The neural mechanisms underlying action selection and how these are affected by normal aging remain to be elucidated. In the present cross-sectional study,...
In complex everyday environments, action selection is critical for optimal goal-directed behavior. This refers to the process of choosing a proper action from the range of possible alternatives. The neural mechanisms underlying action selection and how these are affected by normal aging remain to be elucidated. In the present cross-sectional study,...
White matter hyperintensities (WMH) are regions of high signal intensity typically identified on fluid attenuated inversion recovery (FLAIR). Although commonly observed in elderly individuals, they are more prevalent in Alzheimer’s disease (AD) patients. Given that WMH appear relatively homogeneous on FLAIR, they are commonly partitioned into locat...
Objective
We use the dynamic electroencephalography–functional magnetic resonance imaging (EEG‐fMRI) method to incorporate variability in the amplitude and field of the interictal epileptic discharges (IEDs) into the fMRI analysis. We ask whether IED variability analysis can (a) identify additional activated brain regions during the course of IEDs,...
Diffusion-weighted magnetic resonance imaging (dMRI) has become the primary method for non-invasively studying the organization of white matter in the human brain. While many dMRI acquisition sequences have been developed, they all sample q-space in order to characterize water diffusion. Numerous software platforms have been developed for processin...
Objective
studies of motor outcome after Neonatal Arterial Ischemic Stroke (NAIS) often rely on lesion mapping using MRI. However, clinical measurements indicate that motor deficit can be different than what would solely be anticipated by the lesion extent and location. Because this may be explained by the cortical disconnections between motor area...
Alzheimer’s disease (AD) is characterised by degeneration of specific white matter tracts, however the longitudinal trajectory of tract-specific decline has not yet been well described. In this work, we utilise a longitudinal fixel-based analysis framework to investigate specific fibre tracts that exhibit accelerated decline in AD and mild cognitiv...
The CSF-like free water signal fraction is an advanced diffusion MRI metric representing the freely diffusing water in brain tissue. Different methods to calculate the free water signal fraction using constrained spherical deconvolution exist but it is still unknown how variation in data quality and acquisition affect measurements. Using a large cl...
Recent advances in the analysis of diffusion MRI have allowed for the estimation of 3 tissue compartments in the brain from data with only a single non b=0 shell. There is currently no published quantitative comparison between signal fractions derived from either single- or multi-shell methods. Applying both single-shell analysis and multi-shell an...
Despite the typical symmetrical appearance of the human brain, several functional and structural asymmetries have been reported. Language is the most commonly described lateralised cognitive function, relying relatively more on the left hemisphere in over 90% of the population. This is in line with white matter studies which have revealed leftwards...
Background
The brain's white matter undergoes profound changes during early childhood, which are believed to underlie the rapid development of cognitive and behavioral skills during this period. Neurite density, and complexity of axonal projections, have been shown to change across the life span, though changes during early childhood are poorly cha...
Objectives:
Auditory neuropathy (AN) is the term used to describe a group of hearing disorders, in which the hearing impairment occurs as a result of abnormal auditory nerve function. While our understanding of this condition has advanced significantly over recent years, the ability to determine the site of lesion and the extent of dysfunction in...
White matter hyperintensities (WMHs) are known to be associated with cognitive impairment and vascular brain burden. Evidence suggests that the development of focal WMHs is preceded by subtle injury to the white matter integrity of surrounding normal-appearing white matter (NAWM). Diffusion tensor imaging (DTI) supports this, showing mean diffusivi...
The brain's white matter undergoes profound changes during early childhood that are believed to underlie the rapid development of cognitive and behavioral skills across this period. Diffusion MRI estimates of axonal density and dispersion of axonal projections have been shown to increase with brain development. Widespread increases in estimated axo...
Although diffusion-weighted magnetic resonance imaging (dMRI) can take many forms, they all sample q-space in order to characterize water diffusion. Numerous pipelines and software platforms have been built for processing dMRI data, but most work on only a subset of sampling schemes, or implement only parts of the processing workflow. Comparisons a...
Fronto-temporal dementia (FTD) is a neurodegenerative disease characterized by focal atrophy of the gray matter (GM), especially in the frontal and temporal regions. Recent studies suggest a framework where white matter (WM) atrophy plays an important role in FTD pathophysiology. However, these studies often overlook the fact that WM tracts bridgin...
Background and Purpose—
We examined if ischemic stroke is associated with white matter degeneration predominantly confined to the ipsi-lesional tracts or with widespread bilateral axonal loss independent of lesion laterality.
Methods—
We applied a novel fixel-based analysis, sensitive to fiber tract–specific differences within a voxel, to assess a...