384 results match your criteria spherical deconvolution

Peripheral Nerve Focused Ultrasound Lesioning-Visualization and Assessment Using Diffusion Weighted Imaging.

Front Neurol 2021 9;12:673060. Epub 2021 Jul 9.

Institute of Medical Science, University of Toronto, Toronto, ON, Canada.

Magnetic resonance-guided focused ultrasound (MRgFUS) is a non-invasive targeted tissue ablation technique that can be applied to the nervous system. Diffusion weighted imaging (DWI) can visualize and evaluate nervous system microstructure. Tractography algorithms can reconstruct fiber bundles which can be used for treatment navigation and diffusion tensor imaging (DTI) metrics permit the quantitative assessment of nerve microstructure . Read More

View Article and Full-Text PDF

Enhancing the estimation of fiber orientation distributions using convolutional neural networks.

Comput Biol Med 2021 Jul 14;135:104643. Epub 2021 Jul 14.

School of Biomedical Engineering and Imaging Sciences, King's College London, UK.

Local fiber orientation distributions (FODs) can be computed from diffusion magnetic resonance imaging (dMRI). The accuracy and ability of FODs to resolve complex fiber configurations benefits from acquisition protocols that sample a high number of gradient directions, a high maximum b-value, and multiple b-values. However, acquisition time and scanners that follow these standards are limited in clinical settings, often resulting in dMRI acquired at a single shell (single b-value). Read More

View Article and Full-Text PDF

Functional Contributions of the Arcuate Fasciculus to Language Processing.

Front Hum Neurosci 2021 25;15:672665. Epub 2021 Jun 25.

Aphasia Recovery Lab, Department of Psychology, University of California, Berkeley, Berkeley, CA, United States.

Current evidence strongly suggests that the arcuate fasciculus (AF) is critical for language, from spontaneous speech and word retrieval to repetition and comprehension abilities. However, to further pinpoint its unique and differential role in language, its anatomy needs to be explored in greater detail and its contribution to language processing beyond that of known cortical language areas must be established. We address this in a comprehensive evaluation of the specific functional role of the AF in a well-characterized cohort of individuals with chronic aphasia ( = 33) following left hemisphere stroke. Read More

View Article and Full-Text PDF

Connectome analysis of male world-class gymnasts using probabilistic multishell, multitissue constrained spherical deconvolution tracking.

J Neurosci Res 2021 Jul 10. Epub 2021 Jul 10.

Juntendo University Graduate School of Health and Sports Science, Chiba, Japan.

In athletes, long-term intensive training has been shown to increase unparalleled athletic ability and might induce brain plasticity. We evaluated the structural connectome of world-class gymnasts (WCGs), as mapped by diffusion-weighted magnetic resonance imaging probabilistic tractography and a multishell, multitissue constrained spherical deconvolution method to increase the precision of tractography at the tissue interfaces. The connectome was mapped in 10 Japanese male WCGs and in 10 age-matched male controls. Read More

View Article and Full-Text PDF

Structural impairments in hippocampal and occipitotemporal networks specifically contribute to decline in place and face category processing but not to other visual object categories in healthy aging.

Brain Behav 2021 Jun 29:e02127. Epub 2021 Jun 29.

Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), Institute for Nuclear Sciences Applied to Health (ICNAS), University of Coimbra, Coimbra, Portugal.

Background: Functional neuroimaging studies have identified a set of nodes in the occipital-temporal cortex that preferentially respond to faces in comparison with other visual objects. By contrast, the processing of places seems to rely on parahippocampal cortex and structures heavily implicated in memory (e.g. Read More

View Article and Full-Text PDF

Learning to estimate the fiber orientation distribution function from diffusion-weighted MRI.

Neuroimage 2021 Jun 26:118316. Epub 2021 Jun 26.

Computational Radiology Laboratory (CRL), Department of Radiology, Boston Children's Hospital, and Harvard Medical School, USA.

Estimation of white matter fiber orientation distribution function (fODF) is the essential first step for reliable brain tractography and connectivity analysis. Most of the existing fODF estimation methods rely on sub-optimal physical models of the diffusion signal or mathematical simplifications, which can impact the estimation accuracy. In this paper, we propose a data-driven method that avoids some of these pitfalls. Read More

View Article and Full-Text PDF

White matter integrity in a rat model of epileptogenesis: structural connectomics and fixel-based analysis.

Brain Connect 2021 Jun 22. Epub 2021 Jun 22.

Ghent University Faculty of Engineering and Architecture, 86795, Gent, Belgium;

Introduction: Electrophysiological and neuroimaging studies have demonstrated that large-scale brain networks are affected during the development of epilepsy. These networks can be investigated using diffusion magnetic resonance imaging (dMRI). The most commonly used model to analyze dMRI is diffusion tensor imaging (DTI). Read More

View Article and Full-Text PDF

Structural connectivity changes in the cerebral pain matrix in burning mouth syndrome: a multi-shell, multi-tissue-constrained spherical deconvolution model analysis.

Neuroradiology 2021 Jun 18. Epub 2021 Jun 18.

Department of Radiology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.

Purpose: Burning mouth syndrome (BMS) is a chronic intraoral pain syndrome. Previous studies have attempted to determine the brain connectivity features in BMS using functional and structural magnetic resonance imaging. However, no study has investigated the structural connectivity using multi-shell, multi-tissue-constrained spherical deconvolution (MSMT-CSD), anatomically constrained tractography (ACT), and spherical deconvolution informed filtering of tractograms (SIFT). Read More

View Article and Full-Text PDF

Fiber orientation distribution from diffusion MRI: Effects of inaccurate response function calibration.

J Neuroimaging 2021 Jun 15. Epub 2021 Jun 15.

Image Sciences Institute, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands.

Background And Purpose: Diffusion MRI of the brain enables to quantify white matter fiber orientations noninvasively. Several approaches have been proposed to estimate such characteristics from diffusion MRI data with spherical deconvolution being one of the most widely used methods. Spherical deconvolution requires to define--or derive from the data--a response function, which is used to compute the fiber orientation distribution (FOD). Read More

View Article and Full-Text PDF

Tracking white-matter brain modifications in chronic non-bothersome acoustic trauma tinnitus.

Neuroimage Clin 2021 May 8;31:102696. Epub 2021 May 8.

Univ. Grenoble Alpes, Inserm U1216, Grenoble Institut Neurosciences, 38000 Grenoble, France. Electronic address:

Subjective tinnitus is a symptom characterized by the perception of sound with no external acoustic source, most often accompanied by co-morbidities. To date, the specific role of white matter abnormalities related to tinnitus reaches no consensus in the literature. The goal of this study was to explore the structural connectivity related to tinnitus percept per se, thus focusing on a specific population presenting chronic non-bothersome tinnitus of similar etiology (noise induced) without co-morbidities. Read More

View Article and Full-Text PDF

Comparison of multiple tractography methods for reconstruction of the retinogeniculate visual pathway using diffusion MRI.

Hum Brain Mapp 2021 Aug 12;42(12):3887-3904. Epub 2021 May 12.

Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.

The retinogeniculate visual pathway (RGVP) conveys visual information from the retina to the lateral geniculate nucleus. The RGVP has four subdivisions, including two decussating and two nondecussating pathways that cannot be identified on conventional structural magnetic resonance imaging (MRI). Diffusion MRI tractography has the potential to trace these subdivisions and is increasingly used to study the RGVP. Read More

View Article and Full-Text PDF

Validating pore size estimates in a complex microfiber environment on a human MRI system.

Magn Reson Med 2021 09 7;86(3):1514-1530. Epub 2021 May 7.

Cardiff University Brain Research Imaging Centre (CUBRIC), Cardiff University, Cardiff, United Kingdom.

Purpose: Recent advances in diffusion-weighted MRI provide "restricted diffusion signal fraction" and restricting pore size estimates. Materials based on co-electrospun oriented hollow cylinders have been introduced to provide validation for such methods. This study extends this work, exploring accuracy and repeatability using an extended acquisition on a 300 mT/m gradient human MRI scanner, in substrates closely mimicking tissue, that is, non-circular cross-sections, intra-voxel fiber crossing, intra-voxel distributions of pore-sizes, and smaller pore-sizes overall. Read More

View Article and Full-Text PDF
September 2021

White matter microstructure in youth at risk for serious mental illness: A comparative analysis.

Psychiatry Res Neuroimaging 2021 06 20;312:111289. Epub 2021 Apr 20.

Department of Radiology, University of Calgary, Calgary, Alberta, Canada; Department of Radiology, Alberta Children's Hospital Research Institute,; Department of Radiology, Child and Adolescent Imaging Research Program, Calgary, Alberta, Canada.

Identifying biomarkers of serious mental illness, such as altered white matter microstructure, can aid in early diagnosis and treatment. White matter microstructure was assessed using constrained spherical deconvolution of diffusion imaging data in a sample of 219 youth (age 12-25 years, 64.84% female) across 8 sites. Read More

View Article and Full-Text PDF

Synchrotron X-ray micro-CT as a validation dataset for diffusion MRI in whole mouse brain.

Magn Reson Med 2021 08 25;86(2):1067-1076. Epub 2021 Mar 25.

Department of Radiology, University of Chicago, Chicago, Illinois, USA.

Purpose: To introduce synchrotron X-ray microcomputed tomography (microCT) and demonstrate its use as a natively isotropic, nondestructive, 3D validation modality for diffusion MRI in whole, fixed mouse brain.

Methods: Postmortem diffusion MRI and microCT data were acquired of the same whole mouse brain. Diffusion data were processed using constrained spherical deconvolution. Read More

View Article and Full-Text PDF

From Neurosurgical Planning to Histopathological Brain Tumor Characterization: Potentialities of Arcuate Fasciculus Along-Tract Diffusion Tensor Imaging Tractography Measures.

Front Neurol 2021 26;12:633209. Epub 2021 Feb 26.

Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy.

Tractography has been widely adopted to improve brain gliomas' surgical planning and guide their resection. This study aimed to evaluate state-of-the-art of arcuate fasciculus (AF) tractography for surgical planning and explore the role of along-tract analyses for characterizing tumor histopathology. High angular resolution diffusion imaging (HARDI) images were acquired for nine patients with tumors located in or near language areas (age: 41 ± 14 years, mean ± standard deviation; five males) and 32 healthy volunteers (age: 39 ± 16 years; 16 males). Read More

View Article and Full-Text PDF
February 2021

Personalized biomechanical tongue models based on diffusion-weighted MRI and validated using optical tracking of range of motion.

Biomech Model Mechanobiol 2021 Jun 7;20(3):1101-1113. Epub 2021 Mar 7.

Department of Head and Neck Oncology and Surgery, Netherlands Cancer Institute, Antoni Van Leeuwenhoek Hospital, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands.

For advanced tongue cancer, the choice between surgery and organ-sparing treatment is often dependent on the expected loss of tongue functionality after treatment. Biomechanical models might assist in this choice by simulating the post-treatment function loss. However, this function loss varies between patients and should, therefore, be predicted for each patient individually. Read More

View Article and Full-Text PDF

Detecting Corticospinal Tract Impairment in Tumor Patients With Fiber Density and Tensor-Based Metrics.

Front Oncol 2020 27;10:622358. Epub 2021 Jan 27.

Department of Neurosurgery, Charité-Universitätsmedizin Berlin, Berlin, Germany.

Tumors infiltrating the motor system lead to significant disability, often caused by corticospinal tract injury. The delineation of the healthy-pathological white matter (WM) interface area, for which diffusion magnetic resonance imaging (dMRI) has shown promising potential, may improve treatment outcome. However, up to 90% of white matter (WM) voxels include multiple fiber populations, which cannot be correctly described with traditional metrics such as fractional anisotropy (FA) or apparent diffusion coefficient (ADC). Read More

View Article and Full-Text PDF
January 2021

Preoperative transcranial magnetic stimulation for picture naming is reliable in mapping segments of the arcuate fasciculus.

Brain Commun 2020 29;2(2):fcaa158. Epub 2020 Sep 29.

Department of Neurosurgery, Charité University Hospital, Berlin, Germany.

In preoperative planning for neurosurgery, both anatomical (diffusion imaging tractography) and functional tools (MR-navigated transcranial magnetic stimulation) are increasingly used to identify and preserve eloquent language structures specific to individuals. Using these tools in healthy adults shows that speech production errors occur mainly in perisylvian cortical sites that correspond to subject-specific terminations of the major language pathway, the arcuate fasciculus. It is not clear whether this correspondence remains in oncological patients with altered tissue. Read More

View Article and Full-Text PDF
September 2020

In vivo microstructural heterogeneity of white matter lesions in healthy elderly and Alzheimer's disease participants using tissue compositional analysis of diffusion MRI data.

Neuroimage Clin 2020 26;28:102479. Epub 2020 Oct 26.

Florey Institute of Neuroscience and Mental Health, Melbourne, Victoria, Australia; Florey Department of Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria, Australia.

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 location- or distance-based classes when investigating their relevance to disease. Read More

View Article and Full-Text PDF

Tractographic and Microstructural Analysis of the Dentato-Rubro-Thalamo-Cortical Tracts in Children Using Diffusion MRI.

Cereb Cortex 2021 Mar;31(5):2595-2609

Developmental Imaging and Biophysics Section, UCL-GOS Institute of Child Health, London WC1N 1EH, UK.

The dentato-rubro-thalamo-cortical tract (DRTC) is the main outflow pathway of the cerebellum, contributing to a finely balanced corticocerebellar loop involved in cognitive and sensorimotor functions. Damage to the DRTC has been implicated in cerebellar mutism syndrome seen in up to 25% of children after cerebellar tumor resection. Multi-shell diffusion MRI (dMRI) combined with quantitative constrained spherical deconvolution tractography and multi-compartment spherical mean technique modeling was used to explore the frontocerebellar connections and microstructural signature of the DRTC in 30 healthy children. Read More

View Article and Full-Text PDF

Frontoparietal microstructural damage mediates age-dependent working memory decline in face and body information processing: Evidence for dichotomic hemispheric bias mechanisms.

Neuropsychologia 2021 01 13;151:107726. Epub 2020 Dec 13.

Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), Institute for Nuclear Sciences Applied to Health (ICNAS), Faculty of Medicine, University of Coimbra, Portugal. Electronic address:

Age-associated damage in the microstructure of frontally-based connections (e.g. genu of the corpus callosum and superior longitudinal fasciculus) is believed to lead to impairments in processing speed and executive function. Read More

View Article and Full-Text PDF
January 2021

The role of oxygen in a carbon source (castor oil versus paraffin oil) in the synthesis of carbon nano-onions.

Nanotechnology 2021 Mar;32(13):135603

DSI-NRF Centre of Excellence in Strong Materials, University of the Witwatersrand, 2050, Johannesburg, South Africa. Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, 2050, Johannesburg, South Africa.

The role of a carbon source containing oxygen groups on the physicochemical properties of carbon nano-onions (CNOs) was investigated. Two oils, castor oil (with O groups) and paraffin oil (without O groups) were converted to CNOs in gram-scale yields using an open flame pyrolysis procedure. The products were heated under argon at 900 °C for varying times (1 h, 2 h, 3 h), to investigate the temperature dependence on their structural properties. Read More

View Article and Full-Text PDF

Constrained spherical deconvolution of nonspherically sampled diffusion MRI data.

Hum Brain Mapp 2021 02 10;42(2):521-538. Epub 2020 Nov 10.

Imec-Vision Lab, Department of Physics, University of Antwerp, Antwerp, Belgium.

Constrained spherical deconvolution (CSD) of diffusion-weighted MRI (DW-MRI) is a popular analysis method that extracts the full white matter (WM) fiber orientation density function (fODF) in the living human brain, noninvasively. It assumes that the DW-MRI signal on the sphere can be represented as the spherical convolution of a single-fiber response function (RF) and the fODF, and recovers the fODF through the inverse operation. CSD approaches typically require that the DW-MRI data is sampled shell-wise, and estimate the RF in a purely spherical manner using spherical basis functions, such as spherical harmonics (SH), disregarding any radial dependencies. Read More

View Article and Full-Text PDF
February 2021

Characterisation of white matter asymmetries in the healthy human brain using diffusion MRI fixel-based analysis.

Neuroimage 2021 01 2;225:117505. Epub 2020 Nov 2.

Florey Department of Neuroscience and Mental Health, University of Melbourne, Melbourne, Australia; The University of Sydney, Sydney Imaging, Sydney, Australia; The University of Sydney, School of Biomedical Engineering, Sydney, Australia. Electronic address:

The diffusion tensor model for diffusion MRI has been used extensively to study asymmetry in the human brain white matter. However, given the limitations of the tensor model, the nature of any underlying asymmetries remains uncertain, particularly in crossing fibre regions. Here, we provide a more robust characterisation of human brain white matter asymmetries based on fibre-specific diffusion MRI metrics and a whole-brain data-driven approach. Read More

View Article and Full-Text PDF
January 2021

Assessment of the structural complexity of diffusion MRI voxels using 3D electron microscopy in the rat brain.

Neuroimage 2021 01 2;225:117529. Epub 2020 Nov 2.

A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, PO Box 1627, FI-70211 Kuopio, Finland. Electronic address:

Validation and interpretation of diffusion magnetic resonance imaging (dMRI) requires detailed understanding of the actual microstructure restricting the diffusion of water molecules. In this study, we used serial block-face scanning electron microscopy (SBEM), a three-dimensional electron microscopy (3D-EM) technique, to image seven white and grey matter volumes in the rat brain. SBEM shows excellent contrast of cellular membranes, which are the major components restricting the diffusion of water in tissue. Read More

View Article and Full-Text PDF
January 2021

Fiber-Specific Changes in White Matter Microstructure in Individuals With X-Linked Auditory Neuropathy.

Ear Hear 2020 Nov/Dec;41(6):1703-1714

Department of Otorhinolaryngology, Head and Neck Surgery, Institute of Otolaryngology, Chinese People's Liberation Army General Hospital 301, Beijing, China.

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 affected individuals remains a challenge. To this end, we investigated potential axonal degeneration in the white matter tracts of the brainstem in individuals with X-linked AN. Read More

View Article and Full-Text PDF

Diffusion magnetic resonance imaging assessment of regional white matter maturation in preterm neonates.

Neuroradiology 2021 Apr 29;63(4):573-583. Epub 2020 Oct 29.

Centre for the Developing Brain, School of Imaging Sciences & Biomedical Engineering, King's College London, London, UK.

Purpose: Diffusion magnetic resonance imaging (dMRI) studies report altered white matter (WM) development in preterm infants. Neurite orientation dispersion and density imaging (NODDI) metrics provide more realistic estimations of neurite architecture in vivo compared with standard diffusion tensor imaging (DTI) metrics. This study investigated microstructural maturation of WM in preterm neonates scanned between 25 and 45 weeks postmenstrual age (PMA) with normal neurodevelopmental outcomes at 2 years using DTI and NODDI metrics. Read More

View Article and Full-Text PDF

Diffusion MRI tractography filtering techniques change the topology of structural connectomes.

J Neural Eng 2020 Oct 19. Epub 2020 Oct 19.

Athena Project Team, Université Cote D'Azur, Inria Sophia Antipolis Mediterranean Research Centre, Sophia Antipolis, FRANCE.

Objective: The use of non-invasive techniques for the estimation of structural brain networks (i.e. connectomes) opened the door to large-scale investigations on the functioning and the architecture of the brain, unveiling the link between neurological disorders and topological changes of the brain network. Read More

View Article and Full-Text PDF
October 2020

Preterm birth leads to impaired rich-club organization and fronto-paralimbic/limbic structural connectivity in newborns.

Neuroimage 2021 01 8;225:117440. Epub 2020 Oct 8.

Division of Development and Growth, Department of Woman, Child and Adolescent, University Hospitals of Geneva, Geneva, Switzerland. Electronic address:

Prematurity disrupts brain development during a critical period of brain growth and organization and is known to be associated with an increased risk of neurodevelopmental impairments. Investigating whole-brain structural connectivity alterations accompanying preterm birth may provide a better comprehension of the neurobiological mechanisms related to the later neurocognitive deficits observed in this population. Using a connectome approach, we aimed to study the impact of prematurity on neonatal whole-brain structural network organization at term-equivalent age. Read More

View Article and Full-Text PDF
January 2021

The effect of gradient nonlinearities on fiber orientation estimates from spherical deconvolution of diffusion magnetic resonance imaging data.

Hum Brain Mapp 2021 02 9;42(2):367-383. Epub 2020 Oct 9.

Image Sciences Institute, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands.

Gradient nonlinearities in magnetic resonance imaging (MRI) cause spatially varying mismatches between the imposed and the effective gradients and can cause significant biases in rotationally invariant diffusion MRI measures derived from, for example, diffusion tensor imaging. The estimation of the orientational organization of fibrous tissue, which is nowadays frequently performed with spherical deconvolution techniques ideally using higher diffusion weightings, can likewise be biased by gradient nonlinearities. We explore the sensitivity of two established spherical deconvolution approaches to gradient nonlinearities, namely constrained spherical deconvolution (CSD) and damped Richardson-Lucy (dRL). Read More

View Article and Full-Text PDF
February 2021