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MRI theory and use

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https://www.readbyqxmd.com/read/28630885/bayesian-framework-inspired-no-reference-region-of-interest-quality-measure-for-brain-mri-images
#1
Michael Osadebey, Marius Pedersen, Douglas Arnold, Katrina Wendel-Mitoraj
We describe a postacquisition, attribute-based quality assessment method for brain magnetic resonance imaging (MRI) images. It is based on the application of Bayes theory to the relationship between entropy and image quality attributes. The entropy feature image of a slice is segmented into low- and high-entropy regions. For each entropy region, there are three separate observations of contrast, standard deviation, and sharpness quality attributes. A quality index for a quality attribute is the posterior probability of an entropy region given any corresponding region in a feature image where quality attribute is observed...
April 2017: Journal of Medical Imaging
https://www.readbyqxmd.com/read/28630340/enhancing-t1-magnetic-resonance-imaging-contrast-with-internalized-gadolinium-iii-in-a-multilayer-nanoparticle
#2
Valeria S Marangoni, Oara Neumann, Luke Henderson, Caterina C Kaffes, Hui Zhang, Runmin Zhang, Sandra Bishnoi, Ciceron Ayala-Orozco, Valtencir Zucolotto, James A Bankson, Peter Nordlander, Naomi J Halas
Multifunctional nanoparticles for biomedical applications have shown extraordinary potential as contrast agents in various bioimaging modalities, near-IR photothermal therapy, and for light-triggered therapeutic release processes. Over the past several years, numerous studies have been performed to synthesize and enhance MRI contrast with nanoparticles. However, understanding the MRI enhancement mechanism in a multishell nanoparticle geometry, and controlling its properties, remains a challenge. To systematically examine MRI enhancement in a nanoparticle geometry, we have synthesized MRI-active Au nanomatryoshkas...
June 19, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28620215/theta-band-transcranial-alternating-current-stimulations-modulates-network-behavior-of-dorsal-anterior-cingulate-cortex
#3
Keiichi Onoda, Toshikazu Kawagoe, Haixia Zheng, Shuhei Yamaguchi
Dorsal anterior cingulate cortex (dACC) is an important region in the processing of both cognition and affect. Recently, transcranial brain stimulation has been used to modulate cortical activity, but it is unclear whether this stimulation has a specific effect on dACC. Based on EEG evidence that frontal midline theta activity is generated in dACC, we hypothesized that transcranial alternating current stimulation (tACS) with theta band frequency would modulate neural networks including dACC. In this study, we examined the effects of theta band tACS on functional networks and emotional state...
June 15, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28619436/tumefactive-demyelinating-lesions-a-comprehensive-review
#4
REVIEW
Hussein Algahtani, Bader Shirah, Ali Alassiri
Tumefactive multiple sclerosis or tumefactive demyelinating lesion (TDL) is one of the rare variants of multiple sclerosis (MS) posing a diagnostic challenge and a therapeutic enigma since it is difficult to distinguish from a true central nervous system (CNS) neoplasm or other CNS lesions on magnetic resonance imaging (MRI). The prevalence of TDL is estimated to be 1-3/1000 cases of MS with an annual incidence of 0.3/100,000. This could be an underestimate due to unavailability of a global MS registry and under-reporting of this condition...
May 2017: Multiple Sclerosis and related Disorders
https://www.readbyqxmd.com/read/28617222/an-extensive-assessment-of-network-alignment-algorithms-for-comparison-of-brain-connectomes
#5
Marianna Milano, Pietro Hiram Guzzi, Olga Tymofieva, Duan Xu, Christofer Hess, Pierangelo Veltri, Mario Cannataro
BACKGROUND: Recently the study of the complex system of connections in neural systems, i.e. the connectome, has gained a central role in neurosciences. The modeling and analysis of connectomes are therefore a growing area. Here we focus on the representation of connectomes by using graph theory formalisms. Macroscopic human brain connectomes are usually derived from neuroimages; the analyzed brains are co-registered in the image domain and brought to a common anatomical space. An atlas is then applied in order to define anatomically meaningful regions that will serve as the nodes of the network - this process is referred to as parcellation...
June 6, 2017: BMC Bioinformatics
https://www.readbyqxmd.com/read/28584970/morphometric-evaluation-of-facial-and-vestibulocochlear-nerves-using-magnetic-resonance-imaging-comparison-of-meni%C3%A3-re-s-disease-ears-with-normal-hearing-ears
#6
Annika Henneberger, Birgit Ertl-Wagner, Maximilian Reiser, Robert Gürkov, Wilhelm Flatz
Loss of neural structures (such as hair cells or neurones within the spiral ganglion) has been proposed to be involved in Menière's disease (MD) (Spoendlin et al. Acta oto-laryngologica Supplementum 499:1-21, 1; Merchant et al. Eur Arch Oto-Rhino-Laryngol Off J Eur Feder Oto-Rhino-Laryngol Soc (EUFOS) Affil German Soc Oto-Rhino-Laryngol Head Neck Surg 252(2):63-75, 2; Tsuji et al. Ann Otol Rhinol Laryngol Suppl 81:26-31, 3; Kariya, Otol Neurotol Off Publ Am Otol Soc Am Neurotol Soc Eur Acad Otol Neurotol 28(8):1063-1068, 4; Megerian Laryngoscope 115(9):1525-1535, 5) but this has yet to be confirmed...
June 5, 2017: European Archives of Oto-rhino-laryngology
https://www.readbyqxmd.com/read/28573962/anatomical-integration-and-rich-club-connectivity-in-euthymic-bipolar-disorder
#7
S O'Donoghue, L Kilmartin, D O'Hora, L Emsell, C Langan, S McInerney, N J Forde, A Leemans, B Jeurissen, G J Barker, P McCarthy, D M Cannon, C McDonald
BACKGROUND: Although repeatedly associated with white matter microstructural alterations, bipolar disorder (BD) has been relatively unexplored using complex network analysis. This method combines structural and diffusion magnetic resonance imaging (MRI) to model the brain as a network and evaluate its topological properties. A group of highly interconnected high-density structures, termed the 'rich-club', represents an important network for integration of brain functioning. This study aimed to assess structural and rich-club connectivity properties in BD through graph theory analyses...
July 2017: Psychological Medicine
https://www.readbyqxmd.com/read/28558274/active-control-of-the-spatial-mri-phase-distribution-with-optimal-control-theory
#8
Pauline M Lefebvre, Eric Van Reeth, Hélène Ratiney, Olivier Beuf, Elisabeth Brusseau, Simon A Lambert, Steffen J Glaser, Dominique Sugny, Denis Grenier, Kevin Tse Ve Koon
This paper investigates the use of Optimal Control (OC) theory to design Radio-Frequency (RF) pulses that actively control the spatial distribution of the MRI magnetization phase. The RF pulses are generated through the application of the Pontryagin Maximum Principle and optimized so that the resulting transverse magnetization reproduces various non-trivial and spatial phase patterns. Two different phase patterns are defined and the resulting optimal pulses are tested both numerically with the ODIN MRI simulator and experimentally with an agar gel phantom on a 4...
May 22, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/28549795/brain-grey-and-white-matter-predictors-of-verbal-ability-traits-in-older-age-the-lothian-birth-cohort-1936
#9
Paul Hoffman, Simon R Cox, Dominika Dykiert, Susana Muñoz Maniega, Maria C Valdés Hernández, Mark E Bastin, Joanna M Wardlaw, Ian J Deary
Cerebral grey and white matter MRI parameters are related to general intelligence and some specific cognitive abilities. Less is known about how structural brain measures relate specifically to verbal processing abilities. We used multi-modal structural MRI to investigate the grey matter (GM) and white matter (WM) correlates of verbal ability in 556 healthy older adults (mean age = 72.68 years, s.d. = .72 years). Structural equation modelling was used to decompose verbal performance into two latent factors: a storage factor that indexed participants' ability to store representations of verbal knowledge and an executive factor that measured their ability to regulate their access to this information in a flexible and task-appropriate manner...
May 24, 2017: NeuroImage
https://www.readbyqxmd.com/read/28536804/modeling-dynamic-contrast-enhanced-mri-data-with-a-constrained-local-aif
#10
Chong Duan, Jesper F Kallehauge, Carlos J Pérez-Torres, G Larry Bretthorst, Scott C Beeman, Kari Tanderup, Joseph J H Ackerman, Joel R Garbow
PURPOSE: This study aims to develop a constrained local arterial input function (cL-AIF) to improve quantitative analysis of dynamic contrast-enhanced (DCE)-magnetic resonance imaging (MRI) data by accounting for the contrast-agent bolus amplitude error in the voxel-specific AIF. PROCEDURES: Bayesian probability theory-based parameter estimation and model selection were used to compare tracer kinetic modeling employing either the measured remote-AIF (R-AIF, i.e...
May 23, 2017: Molecular Imaging and Biology: MIB: the Official Publication of the Academy of Molecular Imaging
https://www.readbyqxmd.com/read/28527756/radiological-lumbar-stenosis-severity-predicts-worsening-sagittal-malalignment-on-full-body-standing-stereoradiographs
#11
Aaron J Buckland, Subaraman Ramchandran, Louis Day, Shay Bess, Themistocles Protopsaltis, Peter G Passias, Bassel G Diebo, Renaud Lafage, Virginie Lafage, Akhila Sure, Thomas J Errico
BACKGROUND CONTEXT: Patients with degenerative lumbar stenosis (DLS) adopt a forward flexed posture in an attempt to decompress neural elements. The relationship between sagittal alignment and severity of lumbar stenosis has not previously been studied. PURPOSE: We hypothesized that patients with increasing radiological severity of lumbar stenosis will exhibit worsening sagittal alignment. STUDY DESIGN: This is a cross-sectional study. PATIENT SAMPLE: Our sample consists of patients who have DLS...
May 17, 2017: Spine Journal: Official Journal of the North American Spine Society
https://www.readbyqxmd.com/read/28515708/disrupted-structural-and-functional-networks-and-their-correlation-with-alertness-in-right-temporal-lobe-epilepsy-a-graph-theory-study
#12
Wenyu Jiang, Jianping Li, Xuemei Chen, Wei Ye, Jinou Zheng
Previous studies have shown that temporal lobe epilepsy (TLE) involves abnormal structural or functional connectivity in specific brain areas. However, limited comprehensive studies have been conducted on TLE associated changes in the topological organization of structural and functional networks. Additionally, epilepsy is associated with impairment in alertness, a fundamental component of attention. In this study, structural networks were constructed using diffusion tensor imaging tractography, and functional networks were obtained from resting-state functional MRI temporal series correlations in 20 right temporal lobe epilepsy (rTLE) patients and 19 healthy controls...
2017: Frontiers in Neurology
https://www.readbyqxmd.com/read/28499604/iron-oxide-nanoparticles-in-vivo-in-vitro-biomedical-applications-and-in-silico-studies
#13
REVIEW
Miroslava Nedyalkova, Borjana Donkova, Julia Romanova, George Tzvetkov, Sergio Madurga, Vasil Simeonov
The review presents a broad overview of the biomedical applications of surface functionalized iron oxide nanoparticles (IONPs) as magnetic resonance imaging (MRI) agents for sensitive and precise diagnosis tool and synergistic combination with other imaging modalities. Then, the recent progress in therapeutic applications, such as hyperthermia is discussed and the available toxicity data of magnetic nanoparticles concerning in vitro and in vivo biomedical applications are addressed. This review also presents the available computer models using molecular dynamics (MD), Monte Carlo (MC) and density functional theory (DFT), as a basis for a complete understanding of the behaviour and morphology of functionalized IONPs, for improving NPs surface design and expanding the potential applications in nanomedicine...
May 3, 2017: Advances in Colloid and Interface Science
https://www.readbyqxmd.com/read/28486817/altered-network-topology-in-patients-with-primary-brain-tumors-after-fractionated-radiotherapy
#14
Naeim Bahrami, Tyler M Seibert, Roshan Karunamuni, Hauke Bartsch, AnithaPriya Krishnan, Nikdokht Farid, Jona A Hattangadi-Gluth, Carrie R McDonald
Radiation therapy (RT) is a critical treatment modality for patients with brain tumors, although it can cause adverse effects. Recent data suggest that brain RT is associated with dose-dependent cortical atrophy, which could disrupt neocortical networks. This study examines whether brain RT affects structural network properties in brain tumor patients. We applied graph theory to MRI-derived cortical thickness estimates of 54 brain tumor patients before and after RT. Cortical surfaces were parcellated into 68 regions and correlation matrices were created for patients pre- and post-RT...
June 2017: Brain Connectivity
https://www.readbyqxmd.com/read/28474385/disrupted-topological-organization-of-structural-networks-revealed-by-probabilistic-diffusion-tractography-in-tourette-syndrome-children
#15
Hongwei Wen, Yue Liu, Islem Rekik, Shengpei Wang, Jishui Zhang, Yue Zhang, Yun Peng, Huiguang He
Tourette syndrome (TS) is a childhood-onset neurobehavioral disorder. Although previous TS studies revealed structural abnormalities in distinct corticobasal ganglia circuits, the topological alterations of the whole-brain white matter (WM) structural networks remain poorly understood. Here, we used diffusion MRI probabilistic tractography and graph theoretical analysis to investigate the topological organization of WM networks in 44 drug-naive TS children and 41 age- and gender-matched healthy children. The WM networks were constructed by estimating inter-regional connectivity probability and the topological properties were characterized using graph theory...
May 5, 2017: Human Brain Mapping
https://www.readbyqxmd.com/read/28466257/cortical-representation-of-pain-and-touch-evidence-from-combined-functional-neuroimaging-and-electrophysiology-in-non-human-primates
#16
REVIEW
Li Min Chen
Human functional MRI studies in acute and various chronic pain conditions have revolutionized how we view pain, and have led to a new theory that complex multi-dimensional pain experience (sensory-discriminative, affective/motivational, and cognitive) is represented by concurrent activity in widely-distributed brain regions (termed a network or pain matrix). Despite these breakthrough discoveries, the specific functions proposed for these regions remain elusive, because detailed electrophysiological characterizations of these regions in the primate brain are lacking...
May 2, 2017: Neuroscience Bulletin
https://www.readbyqxmd.com/read/28465264/quantitative-susceptibility-mapping-as-a-possible-tool-to-radiographically-diagnose-sentinel-headache-associated-with-intracranial-aneurysm-case-report
#17
Daichi Nakagawa, Cameron Cushing, Yasunori Nagahama, Lauren Allan, David Hasan
BACKGROUND: Sentinel headache (SH) occurs before aneurysm rupture in an estimated 15%-60% of cases of aneurysmal subarachnoid hemorrhage (aSAH). By definition, noncontrast computed tomography (CT) scan of the brain and lumbar puncture are both negative in patients presenting with SH. One of the theories explaining this phenomenon is that microhemorrhage (MH) from the aneurysm wall contribute to iron deposition in the interface between the aneurysm wall and brain parenchyma. Quantitative susceptibility mapping (QSM) is a recently introduced magnetic resonance imaging (MRI) technique that has proven capable of localizing the deposition of paramagnetic metals, particularly ferric iron...
April 30, 2017: World Neurosurgery
https://www.readbyqxmd.com/read/28460243/optimal-control-design-of-preparation-pulses-for-contrast-optimization-in-mri
#18
Eric Van Reeth, Hélène Ratiney, Michael Tesch, Denis Grenier, Olivier Beuf, Steffen J Glaser, Dominique Sugny
This work investigates the use of MRI radio-frequency (RF) pulses designed within the framework of optimal control theory for image contrast optimization. The magnetization evolution is modeled with Bloch equations, which defines a dynamic system that can be controlled via the application of the Pontryagin Maximum Principle (PMP). This framework allows the computation of optimal RF pulses that bring the magnetization to a given state to obtain the desired contrast after acquisition. Creating contrast through the optimal manipulation of Bloch equations is a new way of handling contrast in MRI, which can explore the theoretical limits of the system...
April 21, 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/28452522/imaging-local-diffusive-dynamics-using-diffusion-exchange-spectroscopy-mri
#19
Dan Benjamini, Michal E Komlosh, Peter J Basser
The movement of water between microenvironments presents a central challenge in the physics of soft matter and porous media. Diffusion exchange spectroscopy (DEXSY) is a powerful 2D nuclear magnetic resonance method for measuring such exchange, yet it is rarely used because of its long scan time requirements. Moreover, it has never been combined with magnetic resonance imaging (MRI). Using probability theory, we vastly reduce the required data, making DEXSY MRI feasible for the first time. Experiments are performed on a composite nerve tissue phantom with restricted and free water-exchanging compartments...
April 14, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28438464/association-of-medial-prefrontal-cortex-connectivity-with-consciousness-level-and-its-outcome-in-patients-with-acquired-brain-injury
#20
Xiaoyan Liu, Jingqi Li, Jian Gao, Zhen Zhou, Fanxia Meng, Gang Pan, Benyan Luo
Medial prefrontal cortex (mPFC) is usually known for participating in virtually all self related processing. However, few have investigated the role of mPFC in modulating conscious awareness. This study aimed to depict the relationship between the mPFC connectivity and the severity and outcome of the disorders of consciousness (DOC) among patients with acquired brain injury. Thirty-four patients with DOC (17 in a minimally conscious state and 17 in an unresponsive wakefulness syndrome/vegetative state) and 11 healthy controls were recruited, underwent clinical assessment and resting-state functional MRI scan, and were further followed up to evaluate recovery outcome using the Glasgow Outcome Scale...
April 21, 2017: Journal of Clinical Neuroscience: Official Journal of the Neurosurgical Society of Australasia
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