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Ilaria Boscolo Galazzo, Lorenza Brusini, Silvia Obertino, Mauro Zucchelli, Cristina Granziera, Gloria Menegaz
Recent tract-based analyses provided evidence for the exploitability of 3D-SHORE microstructural descriptors derived from diffusion MRI (dMRI) in revealing white matter (WM) plasticity. In this work, we focused on the main open issues left: (1) the comparative analysis with respect to classical tensor-derived indices, i.e., Fractional Anisotropy (FA) and Mean Diffusivity (MD); and (2) the ability to detect plasticity processes in gray matter (GM). Although signal modeling in GM is still largely unexplored, we investigated their sensibility to stroke-induced microstructural modifications occurring in the contralateral hemisphere...
2018: Frontiers in Neuroscience
H B Stolp, G Ball, P-W So, J-D Tournier, M Jones, C Thornton, A D Edwards
A key challenge in medical imaging is determining a precise correspondence between image properties and tissue microstructure. This comparison is hindered by disparate scales and resolutions between medical imaging and histology. We present a new technique, 3D Bridging of Optically-clear histology with Neuroimaging Data (3D-BOND), for registering medical images with 3D histology to overcome these limitations. Ex vivo 120 × 120 × 200 μm resolution diffusion-MRI (dMRI) data was acquired at 7 T from adult C57Bl/6 mouse hippocampus...
March 5, 2018: Scientific Reports
Giorgio M Innocenti, Roberto Caminiti, Eric M Rouiller, Graham Knott, Tim B Dyrby, Maxime Descoteaux, Jean-Philippe Thiran
The axonal composition of cortical projections originating in premotor, supplementary motor (SMA), primary motor (a4), somatosensory and parietal areas and descending towards the brain stem and spinal cord was characterized in the monkey with histological tract tracing, electron microscopy (EM) and diffusion MRI (dMRI). These 3 approaches provided complementary information. Histology provided accurate assessment of axonal diameters and size of synaptic boutons. dMRI revealed the topography of the projections (tractography), notably in the internal capsule...
February 27, 2018: Cerebral Cortex
Graham L Baum, David R Roalf, Philip A Cook, Rastko Ciric, Adon F G Rosen, Cedric Xia, Mark A Elliott, Kosha Ruparel, Ragini Verma, Birkan Tunc, Ruben C Gur, Raquel E Gur, Danielle S Bassett, Theodore D Satterthwaite
Multiple studies have shown that data quality is a critical confound in the construction of brain networks derived from functional MRI. This problem is particularly relevant for studies of human brain development where important variables (such as participant age) are correlated with data quality. Nevertheless, the impact of head motion on estimates of structural connectivity derived from diffusion tractography methods remains poorly characterized. Here, we evaluated the impact of in-scanner head motion on structural connectivity using a sample of 949 participants (ages 8-23 years old) who passed a rigorous quality assessment protocol for diffusion magnetic resonance imaging (dMRI) acquired as part of the Philadelphia Neurodevelopmental Cohort...
February 24, 2018: NeuroImage
Thomas Schultz, Anna Vilanova
Modern diffusion magnetic resonance imaging (dMRI) acquires intricate volume datasets and biological meaning can only be found in the relationship between its different measurements. Suitable strategies for visualizing these complicated data have been key to interpretation by physicians and neuroscientists, for drawing conclusions on brain connectivity and for quality control. This article provides an overview of visualization solutions that have been proposed to date, ranging from basic grayscale and color encodings to glyph representations and renderings of fiber tractography...
February 27, 2018: NMR in Biomedicine
Vadivalagia Nambi Sivakumar, Venkatraman Indiran, Babu Peter Sathyanathan
Objective: The aim of this study was to evaluate and compare the diagnostic accuracy of dynamic contrast- enhanced magnetic resonance imaging (dMRI) and isotope renogram in the functional evaluation of pelviureteric junction obstruction (PUJO). Material and methods: Forty-two patients included in the study were investigated with isotope renogram and subsequently, subjected to dMRI. Time-activity curves were generated for both isotope renogram and dMRI. Out of the 42 cases, 9 cases were conservatively managed...
January 2018: Turkish Journal of Urology
Lipeng Ning, Markus Nilsson, Samo Lasič, Carl-Fredrik Westin, Yogesh Rathi
The rate of water exchange across cell membranes is a parameter of biological interest and can be measured by diffusion magnetic resonance imaging (dMRI). In this work, we investigate a stochastic model for the diffusion-and-exchange of water molecules. This model provides a general solution for the temporal evolution of dMRI signal using any type of gradient waveform, thereby generalizing the signal expressions for the Kärger model. Moreover, we also derive a general nth order cumulant expansion of the dMRI signal accounting for water exchange, which has not been explored in earlier studies...
February 21, 2018: Journal of Chemical Physics
M P Noonan, R B Mars, J Sallet, R I M Dunbar, L K Fellows
Social skills rely on a specific set of cognitive processes, raising the possibility that individual differences in social networks are related to differences in specific brain structural and functional networks. Here, we tested this hypothesis with multimodality neuroimaging. With diffusion MRI (DMRI), we showed that differences in structural integrity of particular white matter (WM) tracts, including cingulum bundle, extreme capsule and arcuate fasciculus were associated with an individual's social network size (SNS)...
February 19, 2018: Behavioural Brain Research
Michel R T Sinke, Willem M Otte, Daan Christiaens, Oliver Schmitt, Alexander Leemans, Annette van der Toorn, R Angela Sarabdjitsingh, Marian Joëls, Rick M Dijkhuizen
Diffusion MRI (dMRI)-based tractography offers unique abilities to map whole-brain structural connections in human and animal brains. However, dMRI-based tractography indirectly measures white matter tracts, with suboptimal accuracy and reliability. Recently, sophisticated methods including constrained spherical deconvolution (CSD) and global tractography have been developed to improve tract reconstructions through modeling of more complex fiber orientations. Our study aimed to determine the accuracy of connectome reconstruction for three dMRI-based tractography approaches: diffusion tensor (DT)-based, CSD-based and global tractography...
February 20, 2018: Brain Structure & Function
Julie Constanzo, Matthieu Dumont, Réjean Lebel, Luc Tremblay, Kevin Whittingstall, Laurence Masson-Côté, Sameh Geha, Philippe Sarret, Martin Lepage, Benoit Paquette, Maxime Descoteaux
PURPOSE: The analysis of biological and mesoscopic structures properties by diffusion MRI (dMRI) in brain after radiation therapy remains challenging. In our study, we described the consequences associated with an unwanted dose to healthy tissue, assessing radiation-induced brain alterations of living rats with dMRI compared to histopathology and behavioral assays. METHODS: The right primary motor cortex M1 of the rat brain was targeted by stereotactic radiosurgery with a mean radiation dose of 41 Gy...
February 9, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Céline D Alt, Laura Benner, Theresa Mokry, Florian Lenz, Peter Hallscheidt, Christof Sohn, Hans-Ulrich Kauczor, Kerstin A Brocker
Background Dynamic magnetic resonance imaging (dMRI) captures the entire pelvis during Valsalva maneuver and helps diagnosing pelvic floor changes after reconstructive surgery. Purpose To evaluate therapeutic outcome five years after reconstructive surgery using clinical examination, dMRI, and quality-of-life (QOL) questionnaire. Material and Methods Clinical examination, dMRI, and QOL questionnaire were conducted before surgery and in the follow-ups at 12 weeks, one year, and five years in women with pelvic organ prolapse (POP) stage ≥2...
January 1, 2018: Acta Radiologica
Shuo Li, Yanchun Zhu, Yaoqin Xie, Song Gao
Dynamic magnetic resonance imaging (DMRI) is used to noninvasively trace the movements of organs and the process of drug delivery. The results can provide quantitative or semiquantitative pathology-related parameters, thus giving DMRI great potential for clinical applications. However, conventional DMRI techniques suffer from low temporal resolution and long scan time owing to the limitations of the k-space sampling scheme and image reconstruction algorithm. In this paper, we propose a novel DMRI sampling scheme based on a golden-ratio Cartesian trajectory in combination with a compressed sensing reconstruction algorithm...
2018: PloS One
Yulia Surova, Markus Nilsson, Björn Lampinen, Jimmy Lätt, Sara Hall, Håkan Widner, Danielle van Westen, Oskar Hansson
PURPOSE: In Parkinson's disease (PD), pathological microstructural changes occur that may be detected using diffusion magnetic resonance imaging (dMRI). However, there are few longitudinal studies that explore the effect of disease progression on diffusion indices. METHODS: We prospectively included 76 patients with PD and 38 healthy controls (HC), all of whom underwent diffusion kurtosis imaging (DKI) as part of the prospective Swedish BioFINDER study at baseline and 2 years later...
January 24, 2018: Neuroradiology
Chenyu Wang, Alexander Klistorner, Linda Ly, Michael H Barnett
The posterior visual pathway is commonly affected by multiple sclerosis (MS) pathology that results in measurable clinical and electrophysiological impairment. Due to its highly structured retinotopic mapping, the visual pathway represents an ideal substrate for investigating patho-mechanisms in MS. Therefore, a reliable and robust imaging segmentation method for in-vivo delineation of the optic radiations (OR) is needed. However, diffusion-based tractography approaches, which are typically used for OR segmentation are confounded by the presence of focal white matter lesions...
2018: PloS One
Angela Albi, Antonio Meola, Fan Zhang, Pegah Kahali, Laura Rigolo, Chantal M W Tax, Pelin Aksit Ciris, Walid I Essayed, Prashin Unadkat, Isaiah Norton, Yogesh Rathi, Olutayo Olubiyi, Alexandra J Golby, Lauren J O'Donnell
BACKGROUND AND PURPOSE: Diffusion magnetic resonance imaging (dMRI) provides preoperative maps of neurosurgical patients' white matter tracts, but these maps suffer from echo-planar imaging (EPI) distortions caused by magnetic field inhomogeneities. In clinical neurosurgical planning, these distortions are generally not corrected and thus contribute to the uncertainty of fiber tracking. Multiple image processing pipelines have been proposed for image-registration-based EPI distortion correction in healthy subjects...
January 10, 2018: Journal of Neuroimaging: Official Journal of the American Society of Neuroimaging
Vaibhav Mohanty, Emilie T McKinnon, Joseph A Helpern, Jens H Jensen
PURPOSE: To compare estimates for the diffusional kurtosis in brain as obtained from a cumulant expansion (CE) of the diffusion MRI (dMRI) signal and from q-space (QS) imaging. THEORY AND METHODS: For the CE estimates of the kurtosis, the CE was truncated to quadratic order in the b-value and fit to the dMRI signal for b-values from 0 up to 2000s/mm2. For the QS estimates, b-values ranging from 0 up to 10,000s/mm2 were used to determine the diffusion displacement probability density function (dPDF) via Stejskal's formula...
January 3, 2018: Magnetic Resonance Imaging
John Paul Kolcun, Lee Onn Chieng, Karthik Madhavan, Michael Y Wang
Dynamic spinal cord compression has been investigated for several years, but until the advent of open MRI, the use of dynamic MRI (dMRI) did not gain popularity. Several publications have shown that cervical cord compression is both static and dynamic. On many occasions the evaluation of cervical spondylotic myelopathy (CSM) is straightforward, but patients are frequently encountered with a significantly worse clinical examination than would be suggested by radiological images. In this paper, we present an extensive review of the literature in order to describe the importance of dMRI in various settings and applications...
December 2017: Asian Spine Journal
Matthew Cieslak, Tegan Brennan, Wendy Meiring, Lukas J Volz, Clint Greene, Alexander Asturias, Subhash Suri, Scott T Grafton
White matter structures composed of myelinated axons in the living human brain are primarily studied by diffusion-weighted MRI (dMRI). These long-range projections are typically characterized in a two-step process: dMRI signal is used to estimate the orientation of axon segments within each voxel, then these local orientations are linked together to estimate the spatial extent of putative white matter bundles. Tractography, the process of tracing bundles across voxels, either requires computationally expensive (probabilistic) simulations to model uncertainty in fiber orientation or ignores it completely (deterministic)...
December 21, 2017: NeuroImage
Tharindu Ganepola, Zoltan Nagy, Aurobrata Ghosh, Theodore Papadopoulo, Daniel C Alexander, Martin I Sereno
Cortical area parcellation is a challenging problem that is often approached by combining structural imaging (e.g., quantitative T1, diffusion-based connectivity) with functional imaging (e.g., task activations, topological mapping, resting state correlations). Diffusion MRI (dMRI) has been widely adopted to analyse white matter microstructure, but scarcely used to distinguish grey matter regions because of the reduced anisotropy there. Nevertheless, differences in the texture of the cortical 'fabric' have long been mapped by histologists to distinguish cortical areas...
December 20, 2017: NeuroImage
Jian-Kun Dai, Shu-Xia Wang, Dai Shan, Hai-Chen Niu, Hao Lei
Diffusion-weighted magnetic resonance imaging (dMRI) is widely used to study white and gray matter (GM) micro-organization and structural connectivity in the brain. Super-resolution track-density imaging (TDI) is an image reconstruction method for dMRI data, which is capable of providing spatial resolution beyond the acquired data, as well as novel and meaningful anatomical contrast that cannot be obtained with conventional reconstruction methods. TDI has been used to reveal anatomical features in human and animal brains...
December 16, 2017: Neuroscience Bulletin
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