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Magnetic Resonance in Medicine Oct 2003Formalin fixation of tissue is a common laboratory practice. A direct comparison of diffusion tensor imaging (DTI) parameters from mouse brains before (in vivo) and... (Comparative Study)
Comparative Study
Formalin fixation of tissue is a common laboratory practice. A direct comparison of diffusion tensor imaging (DTI) parameters from mouse brains before (in vivo) and after (ex vivo) formalin fixation is reported herein. Five diffusion indices were examined in a cohort of seven mice: relative anisotropy (RA), directional correlation (DC), trace (Tr(D)), trace-normalized axial diffusivity (D(axially)), and radial diffusivity (D(radially)). Seven regions of interest (ROIs), including five in white matter and two in gray matter, were selected for examination. Consistent with previous findings, a significant decrease of Tr(D) was observed for all ROIs after fixation. However, water diffusion anisotropy, as defined by the indices RA, DC, D(axially), and D(radially), remained unchanged after fixation. Thus, fixation does not appear to alter diffusion anisotropy in the mouse brain. This finding supports the utility of diffusion anisotropy analysis of fixed tissue. The combination of DTI measurements and standard histology may shed light on the microstructural determinants of diffusion anisotropy in normal and disease states.
Topics: Animals; Anisotropy; Brain; Diffusion Magnetic Resonance Imaging; Fixatives; Formaldehyde; Male; Mice; Mice, Inbred C57BL; Tissue Fixation; Water
PubMed: 14523960
DOI: 10.1002/mrm.10605 -
Radiology Jan 2002To evaluate differences in white matter diffusion properties as a function of age in healthy children and adolescents.
PURPOSE
To evaluate differences in white matter diffusion properties as a function of age in healthy children and adolescents.
MATERIALS AND METHODS
Echo-planar diffusion-tensor magnetic resonance (MR) imaging was performed in 33 healthy subjects aged 5-18 years who were recruited from a functional imaging study of normal language development. Results of neurologic, psychologic, and structural MR imaging examinations were within the normal range for all subjects. The trace of the apparent diffusion coefficient and fractional anisotropy in white matter were correlated as a function of age by using Spearman rank correlation.
RESULTS
Statistically significant negative correlation of the trace of the apparent diffusion coefficient with age was found throughout the white matter. Significant positive correlation of fractional anisotropy with age was found in the internal capsule, corticospinal tract, left arcuate fasciculus, and right inferior longitudinal fasciculus.
CONCLUSION
Diffusion-tensor MR imaging results indicate that white matter maturation assessed at different ages involves increases in both white matter density and organization during childhood and adolescence. The trace of the apparent diffusion coefficient and fractional anisotropy may reflect different physiologic processes in healthy children and adolescents.
Topics: Adolescent; Age Factors; Anisotropy; Brain; Child; Child, Preschool; Diffusion; Echo-Planar Imaging; Female; Humans; Image Processing, Computer-Assisted; Male
PubMed: 11756728
DOI: 10.1148/radiol.2221010626 -
Biomedical Engineering Online Nov 2007Information on anatomical connectivity in the brain by measurements of the diffusion of water in white matter tracts lead to quantification of local tract directionality...
BACKGROUND
Information on anatomical connectivity in the brain by measurements of the diffusion of water in white matter tracts lead to quantification of local tract directionality and integrity.
METHODS
The combination of connectivity mapping (fibre tracking, FT) with quantitative diffusion fractional anisotropy (FA) mapping resulted in the approach of results based on group-averaged data, named tractwise FA statistics (TFAS). The task of this study was to apply these methods to group-averaged data from different subjects to quantify differences between normal subjects and subjects with defined alterations of the corpus callosum (CC).
RESULTS
TFAS exhibited a significant FA reduction especially in the CC, in agreement with region of interest (ROI)-based analyses.
CONCLUSION
In summary, the applicability of the TFAS approach to diffusion tensor imaging studies of normal and pathologically altered brains was demonstrated.
Topics: Adult; Algorithms; Anisotropy; Biomedical Engineering; Brain; Brain Mapping; Central Nervous System; Corpus Callosum; Diffusion; Diffusion Magnetic Resonance Imaging; Female; Humans; Male; Models, Statistical
PubMed: 17996104
DOI: 10.1186/1475-925X-6-42 -
Magma (New York, N.Y.) Oct 2019Several studies have demonstrated that anisotropic phantoms can be utilized for diffusion magnetic resonance imaging. The purpose of our study was to examine whether...
OBJECTIVE
Several studies have demonstrated that anisotropic phantoms can be utilized for diffusion magnetic resonance imaging. The purpose of our study was to examine whether wood is suitable as an anisotropic phantom material from the viewpoints of affordability and availability. In the current study, wood was used for restricted diffusion, and fibers were used for hindered diffusion.
MATERIALS AND METHODS
Wood and fiber phantoms were made. Diffusion kurtosis images were acquired with three magnetic resonance scanners. Fractional anisotropy, radial diffusivity, axial diffusivity, radial kurtosis and axial kurtosis values were measured. The wood phantom was imaged, and its durability was confirmed. The phantoms were imaged in varying orientations within the magnetic field. The wood was observed using an optical microscope.
RESULTS
Ten kinds of wood and the fiber had a diffusion metrics. The wood diffusion metrics suggested low variation over a period of 9 months. Changing the orientation of the phantoms within the magnetic field resulted in changes in diffusion metrics. Observation of wood vessels and fibers was conducted.
DISCUSSION
Wood and fibers have anisotropy and are promising as phantom materials. The development of anisotropic phantoms that anyone can use is useful for diffusion magnetic resonance imaging research and clinical applications.
Topics: Anisotropy; Artifacts; Brain; Diffusion Magnetic Resonance Imaging; Diffusion Tensor Imaging; Humans; Materials Testing; Phantoms, Imaging; Wood
PubMed: 31144164
DOI: 10.1007/s10334-019-00761-3 -
Brain Connectivity Nov 2016Autism spectrum disorder (ASD) is a neurodevelopmental disorder found to have widespread alterations in the function and synchrony of brain regions. These differences...
Autism spectrum disorder (ASD) is a neurodevelopmental disorder found to have widespread alterations in the function and synchrony of brain regions. These differences may underlie alterations in microstructural organization, such as in white matter pathways. To investigate the diffusion of major white matter tracts, the current study examined multiple indices of white matter diffusion in 42 children and adults with ASD and 44 typically developing (TD) age- and IQ-matched peers using diffusion tensor imaging. Diffusivity measures were compared between groups for the following tracts: bilateral cingulum bundle, corpus callosum, inferior longitudinal fasciculus, superior longitudinal fasciculus, and uncinate fasciculus. Results indicate a significant reduction in fractional anisotropy (FA) for the left superior longitudinal fasciculus (LSLF) in ASD children and adults compared with TD peers. A significant increase in radial diffusivity for ASD participants was also found in the same cluster along the LSLF. In addition, a significant positive correlation emerged for all subjects between FA for the LSLF and age, with FA increasing with age. These findings point to a significant alteration in long-distance white matter connectivity in children and adults with ASD, potentially underscoring the relationship between alterations in white matter diffusion and the ASD phenotype. These results also suggest that the white matter alterations in autism may be subtle and related to the developmental trajectory.
Topics: Adolescent; Adult; Anisotropy; Autism Spectrum Disorder; Brain; Child; Diffusion Tensor Imaging; Female; Humans; Male; Neural Pathways; White Matter; Young Adult
PubMed: 27555361
DOI: 10.1089/brain.2016.0442 -
Medical Image Computing and... 2011Diffusion-weighted imaging (DWI) enables non-invasive investigation and characterization of the white-matter but suffers from a relatively poor resolution. In this work...
Diffusion-weighted imaging (DWI) enables non-invasive investigation and characterization of the white-matter but suffers from a relatively poor resolution. In this work we propose a super-resolution reconstruction (SRR) technique based on the acquisition of multiple anisotropic orthogonal DWI scans. We address the problem of patient motions by aligning the volumes both in space and in q-space. The SRR is formulated as a maximum a posteriori (MAP) problem. It relies on a volume acquisition model which describes the generation of the acquired scans from the unknown high-resolution image. It enables the introduction of image priors that exploit spatial homogeneity and enables regularized solutions. We detail our resulting SRR optimization procedure and report various experiments including numerical simulations, synthetic SRR scenario and real world SRR scenario. Super-resolution reconstruction in DWI may enable DWI to be performed with unprecedented resolution.
Topics: Algorithms; Anisotropy; Brain; Brain Mapping; Computer Simulation; Diffusion; Diffusion Magnetic Resonance Imaging; Humans; Image Processing, Computer-Assisted; Magnetic Resonance Imaging; Models, Statistical; Models, Theoretical; Programming Languages; Software
PubMed: 21995021
DOI: 10.1007/978-3-642-23629-7_16 -
NeuroImage Aug 1999Diffusion tensor imaging is a magnetic resonance method which provides quantitative measurements of the directionality (anisotropy) of diffusion. Anisotropy measurements...
Diffusion tensor imaging is a magnetic resonance method which provides quantitative measurements of the directionality (anisotropy) of diffusion. Anisotropy measurements can be used to obtain quantitative information about the microstructural integrity of white matter tracts. In intact tracts diffusion is restricted and directional because water molecules move predominantly longitudinally to tracts. The aim of this study was to measure the anisotropy of diffusion in patients with chronic hemiparesis. We measured in the corona radiata and the cerebral peduncle in 10 patients with a chronic hemiparesis and supratentorial lesions and 10 control subjects in regions of interest. In all patients anisotropy was reduced in the coronal radiata contralateral to the hemiparesis by more than 3 SD compared to control subjects. In three patients, each of which had a severe hemiparesis, anisotropy in the cerebral peduncle was reduced by more than 3 SD compared to normal control subjects. Our findings suggest that reduced anisotropy is associated with chronic hemiparesis.
Topics: Adult; Anisotropy; Brain; Brain Damage, Chronic; Brain Mapping; Diffusion; Dominance, Cerebral; Extracellular Space; Female; Hemiplegia; Humans; Image Processing, Computer-Assisted; Magnetic Resonance Imaging; Magnetic Resonance Spectroscopy; Male; Middle Aged; Pyramidal Tracts
PubMed: 10417255
DOI: 10.1006/nimg.1999.0456 -
PloS One 2023The caudate nucleus has been thought to be involved in the control of motor commands by the cerebrum, and recent studies suggest that it may play a role in the control...
The caudate nucleus has been thought to be involved in the control of motor commands by the cerebrum, and recent studies suggest that it may play a role in the control of attachment behavior, cognition, emotion, and mental functions. Implied by the basal ganglia's involvement in the execution, planning and control of movement, the caudate nucleus functions in a situation-dependent manner where processing of external stimuli is important on the basis of learning and memory. Sensory processing, which determines the response to external stimuli, has been shown to be related to various brain regions but it remains unknown how sensory processing is associated with the structure of the caudate nucleus and white matter microstructures of the caudate. Using four diffusion parameters derived from diffusion tensor imaging (DTI) (i.e., fractional anisotropy (FA), mean diffusivity (MD), axonal diffusivity (AD), and radial diffusivity (RD)) and the Adolescent/Adult Sensory Profile (AASP) questionnaire of 99 healthy subjects [42 males and 57 females; mean age:26.9 years, standard deviation 6.9], we investigated the relationship between white matter structure in the caudate nucleus and sensory processing. In consistent with what had been suggested by the results of previous studies, we found significant correlations between AD, MD and tactile sensation. Furthermore, we found a significant correlation between AD, MD and tactile sensory avoidance, the AASP sub-scores regarding the tactile senses. To the best of our knowledge, this is the first study to show that DTI diffusion parameters correlate with AASP scores in specific brain regions.
Topics: Male; Adult; Female; Adolescent; Humans; Diffusion Tensor Imaging; Brain; White Matter; Touch; Anisotropy; Perception
PubMed: 37036862
DOI: 10.1371/journal.pone.0284250 -
Biophysical Journal Nov 2005Diffusion of molecules in brain and other tissues is important in a wide range of biological processes and measurements ranging from the delivery of drugs to...
Diffusion of molecules in brain and other tissues is important in a wide range of biological processes and measurements ranging from the delivery of drugs to diffusion-weighted magnetic resonance imaging. Diffusion tensor imaging is a powerful noninvasive method to characterize neuronal tissue in the human brain in vivo. As a first step toward understanding the relationship between the measured macroscopic apparent diffusion tensor and underlying microscopic compartmental geometry and physical properties, we treat a white matter fascicle as an array of identical thick-walled cylindrical tubes arranged periodically in a regular lattice and immersed in an outer medium. Both square and hexagonal arrays are considered. The diffusing molecules may have different diffusion coefficients and concentrations (or densities) in different domains, namely within the tubes' inner core, membrane, myelin sheath, and within the outer medium. Analytical results are used to explore the effects of a large range of microstructural and compositional parameters on the apparent diffusion tensor and the degree of diffusion anisotropy, allowing the characterization of diffusion in normal physiological conditions as well as changes occurring in development, disease, and aging. Implications for diffusion tensor imaging and for the possible in situ estimation of microstructural parameters from diffusion-weighted MR data are discussed in the context of this modeling framework.
Topics: Algorithms; Anisotropy; Biophysical Phenomena; Biophysics; Brain; Central Nervous System; Diffusion; Diffusion Magnetic Resonance Imaging; Humans; Magnetic Resonance Imaging; Models, Anatomic; Models, Biological; Models, Statistical; Models, Theoretical; Myelin Sheath; Neurons
PubMed: 16100258
DOI: 10.1529/biophysj.105.063016 -
AJNR. American Journal of Neuroradiology Mar 2001Diffusion-weighted MR images have enabled measurement of directionality of diffusion (anisotropy) in white matter. To investigate differences in the anisotropy for...
BACKGROUND AND PURPOSE
Diffusion-weighted MR images have enabled measurement of directionality of diffusion (anisotropy) in white matter. To investigate differences in the anisotropy for various types of pathologic findings and the association between the anisotropy of tracts and neurologic dysfunction, we compared the anisotropy of the posterior limb of the internal capsule and the corona radiata between patients with stroke and those with tumors and between patients with and without hemiparesis.
METHODS
Thirty-three patients consisting of 11 with tumors and 22 with ischemic disease (16 acute infarction, four old infarction, and two transient ischemic attack) and nine control patients were studied with a 1.5-T MR imager. Diffusion-weighted images were obtained with diffusion gradients applied in three orthogonal directions. The diffusion anisotropy measurements were obtained from regions of interests defined within the internal capsule and the corona radiata.
RESULTS
The diffusion anisotropy was significantly reduced in all internal capsules and coronae radiata involved by infarcts, tumors, and peritumoral edema compared with that of the control patients (P <.0001). This reduction was most prominent in the tracts involved by tumors (P <.05). The anisotropy of the internal capsules and coronae radiata was significantly decreased in cases with moderate-to-severe hemiparesis as compared with those with no or mild hemiparesis (P <.0001). Diffusion anisotropy tended to be also reduced in normal-appearing internal capsules and coronae radiata that were remote from the involved segment of the corticospinal tract.
CONCLUSION
The degree of impaired diffusion anisotropy may vary in different pathologic conditions and correlate with neurologic dysfunction. The measurement of diffusion anisotropy may provide additional information relating to neurologic function and transneuronal effects.
Topics: Adolescent; Adult; Aged; Aged, 80 and over; Anisotropy; Brain Neoplasms; Cerebral Cortex; Child; Diffusion; Female; Hemiplegia; Humans; Internal Capsule; Magnetic Resonance Imaging; Male; Middle Aged; Retrospective Studies; Stroke
PubMed: 11237966
DOI: No ID Found