467 research outputs found
PEAR: PEriodic And fixed Rank separation for fast fMRI
In functional MRI (fMRI), faster acquisition via undersampling of data can
improve the spatial-temporal resolution trade-off and increase statistical
robustness through increased degrees-of-freedom. High quality reconstruction of
fMRI data from undersampled measurements requires proper modeling of the data.
We present an fMRI reconstruction approach based on modeling the fMRI signal as
a sum of periodic and fixed rank components, for improved reconstruction from
undersampled measurements. We decompose the fMRI signal into a component which
a has fixed rank and a component consisting of a sum of periodic signals which
is sparse in the temporal Fourier domain. Data reconstruction is performed by
solving a constrained problem that enforces a fixed, moderate rank on one of
the components, and a limited number of temporal frequencies on the other. Our
approach is coined PEAR - PEriodic And fixed Rank separation for fast fMRI.
Experimental results include purely synthetic simulation, a simulation with
real timecourses and retrospective undersampling of a real fMRI dataset.
Evaluation was performed both quantitatively and visually versus ground truth,
comparing PEAR to two additional recent methods for fMRI reconstruction from
undersampled measurements. Results demonstrate PEAR's improvement in estimating
the timecourses and activation maps versus the methods compared against at
acceleration ratios of R=8,16 (for simulated data) and R=6.66,10 (for real
data). PEAR results in reconstruction with higher fidelity than when using a
fixed-rank based model or a conventional Low-rank+Sparse algorithm. We have
shown that splitting the functional information between the components leads to
better modeling of fMRI, over state-of-the-art methods
An Occupational Therapy Community-Based Self-Esteem Program for Adolescents Who Have Experienced Burn Injuries
Self-esteem is a problem that adolescent burn survivors deal with on a daily basis. Yet, there is limited research regarding adolescent burns and the psychosocial aspect within their daily occupations. The purpose of this scholarly project was to develop and provide occupational therapists with interventions and outcome measures to utilize in a Self-Esteem Program for implementation in both inpatient and outpatient settings. This program focuses on helping adolescents to regain their self-esteem and confidence when returning back to their communities. Burns have an emotional and behavioral effect on children/adolescents, causing anxiety, pain, distorted self-image, and depression (Pardo, Garcia, Marrero, & Cia, 2008). Occupational therapy would be beneficial to adolescent burn survivors in facilitating a smooth transition back into the community.
A comprehensive literature review was conducted focusing on adolescents 10-21 years of age who experienced a burn injury that affected their daily activities and social participation. A literature review, including occupational therapy theoretical and practice literature, guided the Self-Esteem Program developed for adolescents who have experienced burns and are returning back into the community. The articles included in the literature review were retrieved from PubMed, CINAHL, Google Scholar, The American Journal of Occupational Therapy, and selected professional textbooks.
A Self-Esteem Program based on the Occupational Adaptation Model (Schkade & McClung, 2001) was developed for implementation by occupational therapists employed by inpatient or outpatient burn care settings. The target audience is adolescents who have experienced burns and are returning back into the community. In this program, occupational therapists provide client and caregiver education so both audiences may have a better understanding of burn injuries and the recovery process.
Occupational therapy (OT) offers many benefits to adolescents who have been injured by burns. Goals for interventions that OT provides within the program include: increasing adolescentâs self-esteem, social interaction, assertiveness, and successful reintegration back into their communities. This program is expected to assist adolescents in the realistic analysis of life situations, application of the self-esteem techniques provided within the program, with the anticipation of an improved psychosocial outcome following burn injury. Interventions and outcomes are directed toward increasing the adolescentsâ psychosocial skills for adaptation following burn injury
The effect of realistic geometries on the susceptibility-weighted MR signal in white matter
Purpose: To investigate the effect of realistic microstructural geometry on
the susceptibility-weighted magnetic resonance (MR) signal in white matter
(WM), with application to demyelination.
Methods: Previous work has modeled susceptibility-weighted signals under the
assumption that axons are cylindrical. In this work, we explore the
implications of this assumption by considering the effect of more realistic
geometries. A three-compartment WM model incorporating relevant properties
based on literature was used to predict the MR signal. Myelinated axons were
modeled with several cross-sectional geometries of increasing realism: nested
circles, warped/elliptical circles and measured axonal geometries from electron
micrographs. Signal simulations from the different microstructural geometries
were compared to measured signals from a Cuprizone mouse model with varying
degrees of demyelination.
Results: Results from simulation suggest that axonal geometry affects the MR
signal. Predictions with realistic models were significantly different compared
to circular models under the same microstructural tissue properties, for
simulations with and without diffusion.
Conclusion: The geometry of axons affects the MR signal significantly.
Literature estimates of myelin susceptibility, which are based on fitting
biophysical models to the MR signal, are likely to be biased by the assumed
geometry, as will any derived microstructural properties.Comment: Accepted March 4 2017, in publication at Magnetic Resonance in
Medicin
Detecting microstructural properties of white matter based on compartmentalization of magnetic susceptibility
AbstractThe microscopic structure of neuronal tissue is crucial to brain function, with axon diameter, axonal density and myelination directly influencing signal conduction in the white matter. There is increasing evidence that these microstructural properties alter signal in magnetic resonance imaging (MRI) driven by magnetic susceptibility of different compartments (e.g., myelin sheaths and iron-laden cells). To explain these observations, we have developed a multi-compartmental geometric model of whitematter microstructure. Using a single set of literature parameters, this forward model predicts experimentally observed orientation dependence and temporal evolution of the MRI signal. Where previous models have aimed to explain only the orientation dependence of signal phase, the proposed approach encapsulates the full repertoire of signal behavior. The frequency distribution underlying signal behavior is predicted to be a rich source of microstructural information with relevance to neuronal pathology
Group-PCA for very large fMRI datasets
Increasingly-large datasets (for example, the resting-state fMRI data from the Human Connectome Project) are demanding analyses that are problematic because of the sheer scale of the aggregate data. We present two approaches for applying group-level PCA; both give a close approximation to the output of PCA applied to full concatenation of all individual datasets, while having very low memory requirements regardless of the number of datasets being combined. Across a range of realistic simulations, we find that in most situations, both methods are more accurate than current popular approaches for analysis of multi-subject resting-state fMRI studies. The group-PCA output can be used to feed into a range of further analyses that are then rendered practical, such as the estimation of group-averaged voxelwise connectivity, group-level parcellation, and group-ICA. (C) 2014 Elsevier Inc. All rights reserved.Peer reviewe
Scan time reduction for readout-segmented EPI using simultaneous multislice acceleration: Diffusion-weighted imaging at 3 and 7 Tesla
Purpose:
Readoutâsegmented echoâplanar imaging (rsâEPI) can provide high quality diffusion data because it is less prone to distortion and blurring artifacts than singleâshot echoâplanar imaging (ssâEPI), particularly at higher resolution and higher field. Readout segmentation allows shorter echoâspacing and echo train duration, resulting in reduced image distortion and blurring, respectively, in the phaseâencoding direction. However, these benefits come at the expense of longer scan times because the segments are acquired in multiple repetitions times (TRs). This study shortened rsâEPI scan times by reducing the TR duration with simultaneous multislice acceleration.
Methods:
The blippedâCAIPI method for slice acceleration with reduced gâfactor SNR loss was incorporated into the diffusionâweighted rsâEPI sequence. The rsâ and ssâEPI sequences were compared at a range of resolutions at both 3 and 7 Tesla in terms of image fidelity and diffusion postprocessing results.
Results:
Sliceâaccelerated clinically useful traceâweighted images and tractography results are presented. Tractography analysis showed that the reduced artifacts in rsâEPI allowed better discrimination of tracts than ssâEPI.
Conclusion:
Slice acceleration reduces rsâEPI scan times providing a practical alternative to diffusionâweighted ssâEPI with reduced distortion and high resolution. Magn Reson Med 74:136â149, 2015
Diffusion Tensor Imaging of Dolphin Brains Reveals Direct Auditory Pathway to Temporal Lobe
The brains of odontocetes (toothed whales) look grossly different from their terrestrial relatives. Because of their adaptation to the aquatic environment and their reliance on echolocation, the odontocetesâ auditory system is both unique and crucial to their survival. Yet, scant data exist about the functional organization of the cetacean auditory system. A predominant hypothesis is that the primary auditory cortex lies in the suprasylvian gyrus along the vertex of the hemispheres, with this position induced by expansion of âassociative0 regions in lateral and caudal directions. However, the precise location of the auditory cortex and its connections are still unknown. Here, we used a novel diffusion tensor imaging (DTI) sequence in archival post-mortem brains of a common dolphin (Delphinus delphis) and a pantropical dolphin (Stenella attenuata) to map their sensory and motor systems. Using thalamic parcellation based on traditionally defined regions for the primary visual (V1) and auditory cortex (A1), we found distinct regions of the thalamus connected to V1 and A1. But in addition to suprasylvian-A1, we report here, for the first time, the auditory cortex also exists in the temporal lobe, in a region near cetacean-A2 and possibly analogous to the primary auditory cortex in related terrestrial mammals (Artiodactyla). Using probabilistic tract tracing, we found a direct pathway from the inferior colliculus to the medial geniculate nucleus to the temporal lobe near the sylvian fissure. Our results demonstrate the feasibility of postmortem DTI in archival specimens to answer basic questions in comparative neurobiology in a way that has not previously been possible and shows a link between the cetacean auditory system and those of terrestrial mammals. Given that fresh cetacean specimens are relatively rare, the ability to measure connectivity in archival specimens opens up a plethora of possibilities for investigating neuroanatomy in cetaceans and other species
Some of Our Favorite Tunes : KSU Faculty Jazz Parliament
The KSU Faculty Jazz Parliament present a concert entitled: Some of Our Favorite Tunes .https://digitalcommons.kennesaw.edu/musicprograms/2308/thumbnail.jp
Hybrid-space reconstruction with add-on distortion correction for simultaneous multi-slab diffusion MRI
Purpose: This study aims to propose a model-based reconstruction algorithm
for simultaneous multi-slab diffusion MRI acquired with blipped-CAIPI gradients
(blipped-SMSlab), which can also incorporate distortion correction.
Methods: We formulate blipped-SMSlab in a 4D k-space with kz gradients for
the intra-slab slice encoding and km (blipped-CAIPI) gradients for the
inter-slab encoding. Because kz and km gradients share the same physical axis,
the blipped-CAIPI gradients introduce phase interference in the z-km domain
while motion induces phase variations in the kz-m domain. Thus, our previous
k-space-based reconstruction would need multiple steps to transform data back
and forth between k-space and image space for phase correction. Here we propose
a model-based hybrid-space reconstruction algorithm to correct the phase errors
simultaneously. Moreover, the proposed algorithm is combined with distortion
correction, and jointly reconstructs data acquired with the blip-up/down
acquisition to reduce the g-factor penalty.
Results: The blipped-CAIPI-induced phase interference is corrected by the
hybrid-space reconstruction. Blipped-CAIPI can reduce the g-factor penalty
compared to the non-blipped acquisition in the basic reconstruction.
Additionally, the joint reconstruction simultaneously corrects the image
distortions and improves the 1/g-factors by around 50%. Furthermore, through
the joint reconstruction, SMSlab acquisitions without the blipped-CAIPI
gradients also show comparable correction performance with blipped-SMSlab.
Conclusion: The proposed model-based hybrid-space reconstruction can
reconstruct blipped-SMSlab diffusion MRI successfully. Its extension to a joint
reconstruction of the blip-up/down acquisition can correct EPI distortions and
further reduce the g-factor penalty compared with the separate reconstruction.Comment: 10 figures+tables, 8 supplementary figure
Faculty Jazz Parliament, Introducing Karla Harris
This performance by the KSU Faculty Jazz Parliament introduces Artist-in-Residence jazz vocalist, Karla Harris. Also featured are Sam Skelton and Luke Weathington on reeds, Rob Opitz on trumpet, Wes Funderburk on trombone, Trey Wright on guitar, Tyrone Jackson on piano, Marc Miller on bass, and Justin Chesarek on drums.https://digitalcommons.kennesaw.edu/musicprograms/2043/thumbnail.jp
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