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1

Functional magnetic resonance imaging (FMRI) of the human brain  

Microsoft Academic Search

Functional magnetic resonance imaging (FMRI) can provide detailed images of human brain that reflect localized changes in cerebral blood flow and oxygenation induced by sensory, motor, or cognitive tasks. This review presents methods for gradient-recalled echo-planar functional magnetic resonance imaging (FMRI). Also included is a discussion of the hypothesized basis of FMRI, imaging hardware, a unique visual stimulation apparatus, image

Edgar A. DeYoe; Peter Bandettini; Jay Neitz; David Miller; Paula Winans

1994-01-01

2

Functional magnetic resonance imaging (FMRI) with auditory stimulation in songbirds.  

PubMed

The neurobiology of birdsong, as a model for human speech, is a pronounced area of research in behavioral neuroscience. Whereas electrophysiology and molecular approaches allow the investigation of either different stimuli on few neurons, or one stimulus in large parts of the brain, blood oxygenation level dependent (BOLD) functional Magnetic Resonance Imaging (fMRI) allows combining both advantages, i.e. compare the neural activation induced by different stimuli in the entire brain at once. fMRI in songbirds is challenging because of the small size of their brains and because their bones and especially their skull comprise numerous air cavities, inducing important susceptibility artifacts. Gradient-echo (GE) BOLD fMRI has been successfully applied to songbirds (1-5) (for a review, see (6)). These studies focused on the primary and secondary auditory brain areas, which are regions free of susceptibility artifacts. However, because processes of interest may occur beyond these regions, whole brain BOLD fMRI is required using an MRI sequence less susceptible to these artifacts. This can be achieved by using spin-echo (SE) BOLD fMRI (7,8) . In this article, we describe how to use this technique in zebra finches (Taeniopygia guttata), which are small songbirds with a bodyweight of 15-25 g extensively studied in behavioral neurosciences of birdsong. The main topic of fMRI studies on songbirds is song perception and song learning. The auditory nature of the stimuli combined with the weak BOLD sensitivity of SE (compared to GE) based fMRI sequences makes the implementation of this technique very challenging. PMID:23770665

Van Ruijssevelt, Lisbeth; De Groof, Geert; Van der Kant, Anne; Poirier, Colline; Van Audekerke, Johan; Verhoye, Marleen; Van der Linden, Annemie

2013-06-03

3

Interhemispheric neuroplasticity following limb deafferentation detected by resting-state functional connectivity magnetic resonance imaging (fcMRI) and functional magnetic resonance imaging (fMRI)  

Microsoft Academic Search

Functional connectivity magnetic resonance imaging (fcMRI) studies in rat brain show brain reorganization following peripheral nerve injury. Subacute neuroplasticity was observed 2 weeks following transection of the four major nerves of the brachial plexus. Direct stimulation of the intact radial nerve reveals a functional magnetic resonance imaging (fMRI) activation pattern in the forelimb regions of the sensory and motor cortices that

Christopher P. Pawela; Bharat B. Biswal; Anthony G. Hudetz; Rupeng Li; Seth R. Jones; Younghoon R. Cho; Hani S. Matloub; James S. Hyde

2010-01-01

4

Examining Personality and Alcohol Expectancies Using Functional Magnetic Resonance Imaging (fMRI) with Adolescents*  

PubMed Central

Objective Personality and alcohol expectancies have been examined as risk factors for the initiation and maintenance of alcohol use in adolescents and young adults. Differences in processing appetitive stimuli are seen as a mechanism for personality's influence on behavior, and that mechanism predisposes individuals to form more positive expectancies for alcohol. The go/no-go task has been used to show how personality differences influence responding to appetitive stimuli in adolescents and adults, and functional magnetic resonance imaging (fMRI) has been used to examine the relation of go/no-go responding to personality in adult males. However, no study to date has examined the relation between fMRI responding, personality and alcohol expectancies in adolescents. Method Forty-six adolescents (ages 12?14 years; 61% male) with minimal substance use histories completed measures of neuroticism, extraversion, and alcohol expectancies, and performed a go/no-go task during fMRI acquisition. Results Greater blood oxygen level-dependent (BOLD) response to inhibition predicted fewer expectancies of cognitive and motor improvements but more expectancies of cognitive and motor impairment from alcohol. In addition, extraverted youths reported more positive alcohol expectancies. However, BOLD response did not predict neuroticism or extraversion. Conclusions These preliminary results suggest that decreased inhibitory neural processing may contribute to more positive and less negative expectancies, which can eventually lead to problem drinking. Further, extraversion may also yield more positive expectancies and could underlie a vulnerability to disordered alcohol use.

ANDERSON, KRISTEN G.; SCHWEINSBURG, ALECIA; PAULUS, MARTIN P.; BROWN, SANDRA A.; TAPERT, SUSAN

2008-01-01

5

Interhemispheric neuroplasticity following limb deafferentation detected by resting-state functional connectivity magnetic resonance imaging (fcMRI) and functional magnetic resonance imaging (fMRI).  

PubMed

Functional connectivity magnetic resonance imaging (fcMRI) studies in rat brain show brain reorganization following peripheral nerve injury. Subacute neuroplasticity was observed 2 weeks following transection of the four major nerves of the brachial plexus. Direct stimulation of the intact radial nerve reveals a functional magnetic resonance imaging (fMRI) activation pattern in the forelimb regions of the sensory and motor cortices that is significantly different from that observed in normal rats. Results of this fMRI experiment were used to determine seed voxel regions for fcMRI analysis. Intrahemispheric connectivities in the sensorimotor forelimb representations in both hemispheres are largely unaffected by deafferentation, whereas substantial disruption of interhemispheric sensorimotor cortical connectivity occurs. In addition, significant intra- and interhemispheric changes in connectivities of thalamic nuclei were found. These are the central findings of the study. They could not have been obtained from fMRI studies alone-both fMRI and fcMRI are needed. The combination provides a general marker for brain plasticity. The rat visual system was studied in the same animals as a control. No neuroplastic changes in connectivities were found in the primary visual cortex upon forelimb deafferentation. Differences were noted in regions responsible for processing multisensory visual-motor information. This incidental discovery is considered to be significant. It may provide insight into phantom limb epiphenomena. PMID:19796693

Pawela, Christopher P; Biswal, Bharat B; Hudetz, Anthony G; Li, Rupeng; Jones, Seth R; Cho, Younghoon R; Matloub, Hani S; Hyde, James S

2009-09-28

6

Brain connectivity In listening to affective stimuli: A functional magnetic resonance imaging (fMRI) study and implications for psychotherapy  

Microsoft Academic Search

To investigate the functional connectivity among amygdala, insula, and auditory cortex during affective auditory stimulation and its relevance for psychotherapy, the authors recorded, using functional magnetic resonance imaging (fMRI), the blood oxygenation level-dependent (BOLD) responses of these brain regions in 20 healthy adults while listening to affective sounds (laughing and crying). Their connectivity was analyzed by time-series panel analysis. The

Wolfgang Tschacher; Michael Schildt; Kerstin Sander

2010-01-01

7

Physiological self-regulation of regional brain activity using real-time functional magnetic resonance imaging (fMRI): methodology and exemplary data  

Microsoft Academic Search

A brain–computer interface (BCI) based on real-time functional magnetic resonance imaging (fMRI) is presented which allows human subjects to observe and control changes of their own blood oxygen level-dependent (BOLD) response. This BCI performs data preprocessing (including linear trend removal, 3D motion correction) and statistical analysis on-line. Local BOLD signals are continuously fed back to the subject in the magnetic

Nikolaus Weiskopf; Ralf Veit; Michael Erb; Klaus Mathiak; Wolfgang Grodd; Rainer Goebel; Niels Birbaumer

2003-01-01

8

Error-related processing following severe traumatic brain injury: An event-related functional magnetic resonance imaging (fMRI) study  

PubMed Central

Continuous monitoring of one’s performance is invaluable for guiding behavior towards successful goal attainment by identifying deficits and strategically adjusting responses when performance is inadequate. In the present study, we exploited the advantages of event-related functional magnetic resonance imaging (fMRI) to examine brain activity associated with error-related processing after severe traumatic brain injury (sTBI). fMRI and behavioral data were acquired while 10 sTBI participants and 12 neurologically-healthy controls performed a task-switching cued-Stroop task. fMRI data were analyzed using a random-effects whole-brain voxel-wise general linear model and planned linear contrasts. Behaviorally, sTBI patients showed greater error-rate interference than neurologically-normal controls. fMRI data revealed that, compared to controls, sTBI patients showed greater magnitude error-related activation in the anterior cingulate cortex (ACC) and an increase in the overall spatial extent of error-related activation across cortical and subcortical regions. Implications for future research and potential limitations in conducting fMRI research in neurologically-impaired populations are discussed, as well as some potential benefits of employing multimodal imaging (e.g., fMRI and event-related potentials) of cognitive control processes in TBI.

Sozda, Christopher N.; Larson, Michael J.; Kaufman, David A.S.; Schmalfuss, Ilona M.; Perlstein, William M.

2011-01-01

9

Development of an apparatus and methodology for conducting functional magnetic resonance imaging (fMRI) with pharmacological stimuli in conscious rhesus monkeys  

PubMed Central

Functional magnetic resonance imaging (fMRI) is a technique with significant potential to advance our understanding of multiple brain systems. However, when human subjects undergo fMRI studies they are typically conscious whereas pre-clinical fMRI studies typically utilize anesthesia, which complicates comparisons across studies. Therefore, we have developed an apparatus suitable for imaging conscious rhesus monkeys. In order to minimize subject stress and spatial motion, each subject was acclimated to the necessary procedures over several months. The effectiveness of this process was then evaluated, in fully trained subjects, by quantifying objective physiological measures. These physiological metrics were stable both within and across sessions and did not differ from when these same subjects were immobilized using standard primate handling procedures. Subject motion and blood oxygenation level dependent (BOLD) fMRI measurements were then evaluated by scanning subjects under three different conditions: the absence of stimulation, presentation of a visual stimulus, or administration of intravenous (i.v.) cocaine (0.3 mg/kg). Spatial motion differed neither by condition nor along the three principal axes. In addition, maximum translational and rotational motion never exceeded one half of the voxel size (0.75 mm) or 1.5 degrees, respectively. Furthermore, the localization of changes in blood oxygenation closely matched those reported in previous studies using similar stimuli. These findings document the feasibility of fMRI data collection in conscious rhesus monkeys using these procedures and allow for the further study of the neural effects of psychoactive drugs.

Murnane, Kevin Sean; Howell, Leonard Lee

2010-01-01

10

Conference report: functional magnetic resonance imaging for beginners--a review of the fMRI experience IV, 13-14 May 2002, Natcher Conference Center, National Institutes of Health, Bethesda, MD.  

PubMed

The fourth fMRI Experience meeting was held at the Bethesda, Maryland campus of the National Institutes of Health on May 13th and 14th, 2002. The purpose of the meeting was to provide a platform for students working with functional magnetic resonance imaging (fMRI) to pres ent their research to an international audience of peers. This year"s meeting featured special lectures from Dr. Leslie Ungerleider ("Imaging Mechanisms of Visual Attention") and Dr. Daniel Weinberger ("Genetic Variation and fMRI Response"). PMID:12920320

Caggiano, Daniel; Joffily, Mateus

2002-06-27

11

Does the cerebellum contribute to cognitive aspects of speech production? A functional magnetic resonance imaging (fMRI) study in humans.  

PubMed

Several positron emission tomography (PET) studies suggest a contribution of the lateral aspects of the right cerebellar hemisphere to higher-level (cognitive) aspects of speech production such as controlled verbal response selection. As an alternative, however, 'inner speech', giving rise to subliminal activity of orofacial and laryngeal muscles, might account for the observed activation effects. Eighteen subjects underwent functional magnetic resonance imaging (fMRI) during continuous silent recitation of the names of the months of the year ('automatic speech'). The right cerebellar hemisphere showed a significantly increased hemodynamic response concomitant with, among others, an asymmetric activation pattern towards the left side at the level of the motor strip. Since highly overlearned word strings, presumably, pose few demands on controlled response selection and since the projections of the right cerebellar hemisphere to the left precentral gyrus participate in motor control, the observed cerebellar activation, thus, seems to be related to the articulatory level of speech production rather than, as suggested by previous PET studies, to cognitive operations. PMID:9655624

Ackermann, H; Wildgruber, D; Daum, I; Grodd, W

1998-05-15

12

Impairment of fronto-striatal and parietal cerebral networks correlates with attention deficit hyperactivity disorder (ADHD) psychopathology in adults - a functional magnetic resonance imaging (fMRI) study.  

PubMed

Attention deficit hyperactivity disorder (ADHD) is a common, genetically transmitted common childhood-onset disorder with a high rate of persistence in adulthood. Although many studies have shown anatomical and functional abnormalities in children and adolescents, studies with adult patients are rare. Nineteen adults with ADHD (11 ADHD, combined type; 8 ADHD, partially remitted) and 17 controls were included in this functional magnetic resonance imaging (fMRI) study. Brain activation was investigated with a continuous performance test (CPT). Impaired activation of a fronto-striatal and a parietal attentional network was observed during the NoGo condition in ADHD subjects. Correlations of reduced activity of the caudate nuclei, the anterior cingulate cortex, and parietal cortical structures, as well as increased activity in the insular cortex, with inattention and impulsivity symptom scores were found. The activation patterns were similar to those known from children and adolescents with ADHD. In conclusion we found not only a widespread dysfunction of brain regions that are involved in cognitive processing in adults with ADHD compared with controls, but also correlations between symptom severity and dysfunction of neuronal systems across adult subjects with a history of ADHD in childhood but whose symptoms did (persistent ADHD) and did not (not persistent ADHD) qualify for a full diagnosis of ADHD in adulthood. PMID:20558047

Schneider, Marc F; Krick, Christoph M; Retz, Wolfgang; Hengesch, Georges; Retz-Junginger, Petra; Reith, Wolfgang; Rösler, Michael

2010-06-16

13

Functional Magnetic Resonance Imaging of Eye Dominance at 4 Tesla  

Microsoft Academic Search

We studied eye dominance in visual cortex and lateral geniculate nucleus (LGN) using functional magnetic resonance imaging (fMRI) at a very high magnetic field (4 tesla). Eight normal volunteers were studied with fMRI at 4 tesla during alternating monocular visual stimulation. The acquisition was repeated twice in 4 subjects to confirm reproducibility. In addition, magnetic resonance signal intensities during three

Atsushi Miki; Grant T. Liu; Sarah A. Englander; Theo G. M. van Erp; Gabrielle R. Bonhomme; David O. Aleman; Chia-Shang J. Liu; John C. Haselgrove

2001-01-01

14

Neuronal current distribution imaging using magnetic resonance  

Microsoft Academic Search

A new functional magnetic resonance imaging (fMRI) technique to visualize the distribution of neuronal currents in the human brain was developed Measurements of the internal magnetic field deformation caused by an electric current dipole in a phantom were performed using a method based on the microscopic magnetic resonance imaging technique. The minimal value of the current dipole moment detected by

Hirotake Kamei; Keiji Iramina; K. Yoshikawa; Shoogo Ueno

1999-01-01

15

Functional Magnetic Resonance Imaging and Spectroscopic Imaging of the Brain: Application of fMRI and fMRS to Reading Disabilities and Education.  

ERIC Educational Resources Information Center

|This tutorial/review covers functional brain-imaging methods and results used to study language and reading disabilities. Although the emphasis is on magnetic resonance imaging and functional magnetic resonance spectroscopy, other imaging techniques are also discussed including positron emission tomography, electroencephalography,…

Richards, Todd L.

2001-01-01

16

Functional Magnetic Resonance Imaging and Spectroscopic Imaging of the Brain: Application of fMRI and fMRS to Reading Disabilities and Education.  

ERIC Educational Resources Information Center

This tutorial/review covers functional brain-imaging methods and results used to study language and reading disabilities. Although the emphasis is on magnetic resonance imaging and functional magnetic resonance spectroscopy, other imaging techniques are also discussed including positron emission tomography, electroencephalography,…

Richards, Todd L.

2001-01-01

17

Magnetic resonance imaging of the fetus  

Microsoft Academic Search

Fetal magnetic resonance imaging (FMRI) has gained considerable interest during the last decade, especially in its intracranial\\u000a applications. Due to its high soft-tissue contrast and presumed safety, FMRI should be accepted as a complementary technique\\u000a in prenatal diagnosis, useful either to elucidate equivocal findings on routine US studies or to further delineate some pathological\\u000a entities. Normal patterns of fetal brain

C. Garel; Hervé Brisse; G. Sebag; Monique Elmaleh; Jean-François Oury; Max Hassan

1998-01-01

18

Functional Magnetic Resonance Imaging in Nursing Research  

Microsoft Academic Search

Functional magnetic resonance imaging (fMRI) is a powerful noninvasive neuroimaging technique nurse scientists can use to investigate the structure and cognitive capacities of the brain. A strong magnetic field and intermittent high-frequency pulses cause protons in body tissues to release energy, which can be recorded and processed into images that are sensitive to specific tissue characteristics. Although temporal and spatial

L. Clark Johnson; Todd L. Richards; Kristen H. Archbold; Carol A. Landis

2006-01-01

19

Decoding brain states using functional magnetic resonance imaging  

Microsoft Academic Search

Most leading research in basic and clinical neuroscience has been carried out by functional magnetic resonance imaging (fMRI),\\u000a which detects the blood oxygenation level dependent signals associated with neural activities. Among new fMRI applications,\\u000a brain decoding is an emerging research area, which infers mental states from fMRI signals. Brain decoding using fMRI includes\\u000a classification, identification, and reconstruction of brain states.

Dongha Lee; Changwon Jang; Hae-Jeong Park

2011-01-01

20

A Primer on Functional Magnetic Resonance Imaging  

Microsoft Academic Search

In this manuscript, basic principles of functional magnetic resonance imaging (fMRI) are reviewed. In the first section, two\\u000a intrinsic mechanisms of magnetic resonance image contrast related to the longitudinal and transverse components of relaxing\\u000a spins and their relaxation rates, T1 and T2, are described. In the second section, the biophysical mechanisms that alter the apparent transverse relaxation time, $$T_2^*$$, in

Gregory G. Brown; Joanna E. Perthen; Thomas T. Liu; Richard B. Buxton

2007-01-01

21

Functional magnetic resonance imaging (fMRI) and effects of L-dopa on visual function in normal and amblyopic subjects.  

PubMed Central

PURPOSE: To evaluate the effects of a single dose of levodopa on visual cortex, based on functional MRI (fMRI), and on visual function, based on psychophysical tests, in amblyopic and normal subjects. METHOD: A prospective, randomized trial of a single dose of levodopa (2 mg/kg body weight) was undertaken in an institutional setting in nine normal and six amblyopic subjects, who were assessed at baseline and 90 minutes after levodopa ingestion. fMRI of occipital visual cortex was undertaken with a 1.5T GE MRI scanner utilizing the BOLD contrast technique. fMRI stimuli were two gratings (0.5, 2.0 cycles/degree of visual angle) that counterphased at 4 Hz. fMRI parameters for analysis included AREA and LEVEL of activation and a SUMMED score (AREA x LEVEL). Psychophysical tests included visual acuity, contrast sensitivity, stereoacuity, and binocular fusion. RESULTS: At baseline, AREA of activation (P = .05) and SUMMED score (P = .05) were significantly less in the amblyopic compared to the dominant eyes. Psychophysically, visual acuity and contrast sensitivity were significantly worse in the amblyopic eye. Following levodopa ingestion, there was significant decrease in LEVEL of activation in the amblyopic eye, even though visual acuity showed significant improvement (P = .03). Also, amblyopes showed a significant increase and normals showed some decrease in interocular difference in LEVEL of activation (P = .04). CONCLUSION: Unique information was obtained when fMRI was utilized to assess visual cortical function. While levodopa improved visual acuity in the amblyopic eye, it decreased the LEVEL of activation based on fMRI, a counterintuitive finding. The results highlight the value of utilizing fMRI to assess amblyopia and provide new directions for research.

Rogers, Gary L

2003-01-01

22

Role of functional magnetic resonance imaging in drug discovery  

PubMed Central

In this review, we survey the state of the field of functional magnetic resonance imaging (fMRI) as it relates to drug discovery and drug development. We highlight the advantages and limitations of fMRI for this purpose and suggest ways to improve the use of fMRI for developing new therapeutics, with emphasis on treatments for anxiety disorders. Fundamentally, pharmacological studies with standard psychiatric treatments using standardized behavioral probes during fMRI will need to be carried out to determine characteristic brain signatures that could be used to predict whether novel compounds are likely to have specific therapeutic effects.

Paulus, Martin P.; Stein, Murray B.

2010-01-01

23

The Underpinnings of the BOLD Functional Magnetic Resonance Imaging Signal  

Microsoft Academic Search

The good coverage and high resolution afforded by functional mag-netic resonance imaging (fMRI) make it an excellent tool for the noninvasive imaging of the human brain. Equally interesting, how-ever, is the use of this technique in animal studies using high mag-netic fields. In the latter case, highly spatiotemporally resolved fMRI can reveal how widespread neural networks are organized, and ac-companying

Nikos K. Logothetis

2003-01-01

24

Pitfalls in fMRI  

Microsoft Academic Search

Several different techniques allow a functional assessment of neuronal activations by magnetic resonance imaging (fMRI). The\\u000a by far most influential fMRI technique is based on a local T2*-sensitive hemodynamic response to neuronal activation, also\\u000a known as the blood oxygenation level dependent or BOLD effect. Consequently, the term ‘fMRI’ is often used synonymously with\\u000a BOLD imaging. Because interpretations of fMRI brain

Sven Haller; Andreas J. Bartsch

2009-01-01

25

Transcranial magnetic stimulation assisted by neuronavigation of magnetic resonance images  

NASA Astrophysics Data System (ADS)

Technological advance has improved the way scientists and doctors can learn about the brain and treat different disorders. A non-invasive method used for this is Transcranial Magnetic Stimulation (TMS) based on neuron excitation by electromagnetic induction. Combining this method with functional Magnetic Resonance Images (fMRI), it is intended to improve the localization technique of cortical brain structures by designing an extracranial localization system, based on Alcauter et al. work.

Viesca, N. Angeline; Alcauter, S. Sarael; Barrios, A. Fernando; González, O. Jorge J.; Márquez, F. Jorge A.

2012-10-01

26

Nuclear magnetic resonance spectroscopy  

Microsoft Academic Search

Magnetic resonance spectroscopy is a valuable method for the non-invasive investigation of metabolic processes and can now be combined with conventional magnetic resonance imaging in patients. This article gives a brief introduction into the principles and physiological and clinical applications of in vivo proton magnetic resonance spectroscopy, surveys experiences in healthy volunteers and presents exemplary results in patients suffering from

Armin Ettl; Christa Fischer-Klein; Andreas Chemelli; Albert Daxer; Stephan Felber

1994-01-01

27

Imaginative resonance training (IRT) achieves elimination of amputees' phantom pain (PLP) coupled with a spontaneous in-depth proprioception of a restored limb as a marker for permanence and supported by pre-post functional magnetic resonance imaging (fMRI).  

PubMed

Non-pharmacological approaches such as mirror therapy and graded motor imagery often provide amelioration of amputees' phantom limb pain (PLP), but elimination has proved difficult to achieve. Proprioception of the amputated limb has been noted in studies to be defective and/or distorted in the presence of PLP, but has not, apparently, been researched for various stages of amelioration up to the absence of PLP. Previous studies using functional magnetic resonance imaging (fMRI) suggested that pathological cortical reorganisation after amputation may be the underlying neurobiological correlate of PLP. We report two cases of permanent elimination of PLP after application of imaginative resonance training. The patients, 69 years and 84 years old, reported freedom from PLP together with in-depth achievement of proprioception of a restored limb at the end of the treatment, which may thus be taken as an indication of permanence. Pre/post fMRI for the first case showed, against a group of healthy controls, analogous changes of activation in the sensorimotor cortex. PMID:22748628

Meyer, Paul; Matthes, Christoph; Kusche, Karl Erwin; Maurer, Konrad

2012-06-27

28

Modeling functional Magnetic Resonance Imaging (fMRI) experimental variables in the Ontology of Experimental Variables and Values (OoEVV).  

PubMed

Neuroimaging data is raw material for cognitive neuroscience experiments, leading to scientific knowledge about human neurological and psychological disease, language, perception, attention and ultimately, cognition. The structure of the variables used in the experimental design defines the structure of the data gathered in the experiments; this in turn structures the interpretative assertions that may be presented as experimental conclusions. Representing these assertions and the experimental data which support them in a computable way means that they could be used in logical reasoning environments, i.e. for automated meta-analyses, or linking hypotheses and results across different levels of neuroscientific experiments. Therefore, a crucial first step in being able to represent neuroimaging results in a clear, computable way is to develop representations for the scientific variables involved in neuroimaging experiments. These representations should be expressive, computable, valid, extensible, and easy-to-use. They should also leverage existing semantic standards to interoperate easily with other systems. We present an ontology design pattern called the Ontology of Experimental Variables and Values (OoEVV). This is designed to provide a lightweight framework to capture mathematical properties of data, with appropriate 'hooks' to permit linkage to other ontology-driven projects (such as the Ontology of Biomedical Investigations, OBI). We instantiate the OoEVV system with a small number of functional Magnetic Resonance Imaging datasets, to demonstrate the system's ability to describe the variables of a neuroimaging experiment. OoEVV is designed to be compatible with the XCEDE neuroimaging data standard for data collection terminology, and with the Cognitive Paradigm Ontology (CogPO) for specific reasoning elements of neuroimaging experimental designs. PMID:23684873

Burns, Gully A P C; Turner, Jessica A

2013-05-16

29

[Clinical application of functional magnetic resonance imaging].  

PubMed

Three types of researches have been carried out on brain-mind relationships: 1. researches on anatomical correlates of special talents (for example, perfect pitch) or deficits (for example, dyslexia), 2. researches to examine the relationship between a given cognitive syndrome and the site of brain damage, 3. researches to localize human cognitive function in the brain in vivo using functional magnetic resonance imaging (fMRI) and positron emission tomography (PET). fMRI is a particularly important because it is noninvasive. A tutorial covering basic aspects of this methodology is presented, along with a survey of recent fMRI data related to clinical application. Future investigations of the three types enumerated above are expected to further clarify brain-mind relationships. PMID:11905006

Sugishita, Morihiro

2002-03-01

30

Functional magnetic resonance imaging in schizophrenia  

PubMed Central

The integration of functional magnetic resonance imaging (fMRI) with cognitive and affective neuroscience paradigms enables examination of the brain systems underlying the behavioral deficits manifested in schizophrenia; there have been a remarkable increase in the number of studies that apply fMRI in neurobiological studies of this disease. This article summarizes features of fMRI methodology and highlights its application in neurobehavioral studies in schizophrenia. Such work has helped elucidate potential neural substrates of deficits in cognition and affect by providing measures of activation to neurobehavioral probes and connectivity among brain regions. Studies have demonstrated abnormalities at early stages of sensory processing that may influence downstream abnormalities in more complex evaluative processing. The methodology can help bridge integration with neuropharmacologic and genomic investigations.

Gur, Raquel E.; Gur, Ruben C.

2010-01-01

31

fMRI Supports the Sensorimotor Theory of Motor Resonance  

PubMed Central

The neural mechanisms mediating the activation of the motor system during action observation, also known as motor resonance, are of major interest to the field of motor control. It has been proposed that motor resonance develops in infants through Hebbian plasticity of pathways connecting sensory and motor regions that fire simultaneously during imitation or self movement observation. A fundamental problem when testing this theory in adults is that most experimental paradigms involve actions that have been overpracticed throughout life. Here, we directly tested the sensorimotor theory of motor resonance by creating new visuomotor representations using abstract stimuli (motor symbols) and identifying the neural networks recruited through fMRI. We predicted that the network recruited during action observation and execution would overlap with that recruited during observation of new motor symbols. Our results indicate that a network consisting of premotor and posterior parietal cortex, the supplementary motor area, the inferior frontal gyrus and cerebellum was activated both by new motor symbols and by direct observation of the corresponding action. This tight spatial overlap underscores the importance of sensorimotor learning for motor resonance and further indicates that the physical characteristics of the perceived stimulus are irrelevant to the evoked response in the observer.

Grafton, Scott T.; Della-Maggiore, Valeria

2011-01-01

32

A stereotactic method for image-guided transcranial magnetic stimulation validated with fMRI and motor-evoked potentials  

Microsoft Academic Search

Transcranial Magnetic Stimulation (TMS) delivers short magnetic pulses that penetrate the skull unattenuated, disrupting neural processing in a noninvasive, reversible way. To disrupt specific neural processes, coil placement over the proper site is critical. Therefore, a neural navigator (NeNa) was developed. NeNa is a frameless stereotactic device using structural and functional magnetic resonance imaging (fMRI) data to guide TMS coil

S. F. W. Neggers; T. R. Langerak; D. J. L. G. Schutter; R. C. W. Mandl; N. F. Ramsey; P. J. J. Lemmens; A. Postma

2004-01-01

33

Sensors for Applications in Magnetic Resonance Environments  

Microsoft Academic Search

This paper analyzes sensing methods compatible with magnetic resonance imaging (MRI) and functional MRI (fMRI) reported in the literature, and presents the three generations of MR-compatible force\\/torque sensors we have developed for robotic systems to interact with human motion. Conventional sensors such as camera-based measurement systems, strain gauges or commercial force\\/torque sensors, and optical encoders may be used, if placed

Roger Gassert; Dominique Chapuis; Hannes Bleuler; Etienne Burdet

2008-01-01

34

Functional magnetic resonance imaging studies of language  

Microsoft Academic Search

Functional neuroimaging of language builds on almost 150 years of study in neurology, psychology, linguistics, anatomy, and\\u000a physiology. In recent years, there has been an explosion of research using functional imaging technology, especially positron\\u000a emission tomography (PET) and functional magnetic resonance imaging (fMRI), to understand the relationship between brain mechanisms\\u000a and language processing. These methods combine highresolution anatomic images with

Steven L. Small; Martha W. Burton

2002-01-01

35

Multisensory functional magnetic resonance imaging: a future perspective  

Microsoft Academic Search

Advances in functional magnetic resonance imaging (fMRI) technology and analytic tools provide a powerful approach to unravel\\u000a how the human brain combines the different sensory systems. In this perspective, we outline promising future directions of\\u000a fMRI to make optimal use of its strengths in multisensory research, and to meet its weaker sides by combining it with other\\u000a imaging modalities and

Rainer Goebel; Nienke van Atteveldt

2009-01-01

36

BRAIN ACTIVITY MEASURED BY FUNCTIONAL MAGNETIC RESONANCE IMAGING (fMRI) IS RELATED TO PATIENT-REPORTED SEVERITY OF URGENCY URINARY INCONTINENCE  

PubMed Central

Purpose To investigate the relationship between experimental neuroimaging and self-reported measures of urinary incontinence. Materials and Methods We evaluated 14 functionally independent, community-dwelling older women (> 60 years) who had moderate to severe urgency urinary incontinence. All underwent detailed clinical assessment (3-day bladder diary, 24-hour pad test, and quality of life assessment), urodynamic testing, and functional brain scanning. Brain activity during reported urgency was assessed using a method that combines fMRI with simultaneous urodynamic monitoring during repeated cycles of bladder filling/emptying. We used SPM2, a statistical parametric mapping program, to correlate brain activity with relevant clinical covariates, including number of urgency incontinent episodes, amount of urine leakage, and psychological burden as assessed by the Urge Impact Scale (URIS-24) questionnaire. Results Activity in rostral and subgenual anterior cingulate gyrus, insula, inferior frontal gyrus, orbitofrontal cortex, dorsal and posterior cingulate gyrus, parahippocampus, cuneus and parts of parieto-temporal lobe correlated positively with daytime incontinence frequency and urine loss. Different brain regions correlated with the psychological burden, and the associations were inverse: precuneus/cuneus and posterior cingulate gyrus, superior temporal, supramarginal, and transverse gyrus. Conclusions Regional brain activity in the setting of self-reported urgency, as provoked by bladder filling, correlates significantly with the severity of incontinence in daily life as well as the associated psychological burden. Thus, observations made under experimental conditions correlate with patients’ real-life experience and suggest neural correlates of urgency incontinence symptoms that could be used as potential targets for future investigations.

Tadic, Stasa D.; Griffiths, Derek; Schaefer, Werner; Cheng, Cathy I.; Resnick, Neil M.

2010-01-01

37

Functional magnetic resonance imaging using RASER  

PubMed Central

Although functional imaging of neuronal activity by magnetic resonance imaging (fMRI) has become the primary methodology employed in studying the brain, significant portions of the brain are inaccessible by this methodology due to its sensitivity to macroscopic magnetic field inhomogeneities induced near air filled cavities in the head. In this paper, we demonstrate that this sensitivity is eliminated by a novel pulse sequence, RASER (rapid acquisition by sequential excitation and refocusing) (Chamberlain et al., 2007), that can generate functional maps. This is accomplished because RASER acquired signals are purely and perfectly T2 weighted, without any T2*-effects that are inherent in the other image acquisition schemes employed to date. T2-weighted fMRI sequences are also more specific to the site of neuronal activity at ultrahigh magnetic fields than T2*-variations since they are dominated by signal components originating from the tissue in the capillary bed. The RASER based fMRI response is quantified; it is shown to have inherently less noisy time series and to provide fMRI in brain regions, such as the orbitofrontal cortex, which are challenging to image with conventional techniques.

Goerke, Ute; Garwood, Michael; Ugurbil, Kamil

2010-01-01

38

Functional magnetic resonance imaging using RASER.  

PubMed

Although functional imaging of neuronal activity by magnetic resonance imaging (fMRI) has become the primary methodology employed in studying the brain, significant portions of the brain are inaccessible by this methodology due to its sensitivity to macroscopic magnetic field inhomogeneities induced near air-filled cavities in the head. In this paper, we demonstrate that this sensitivity is eliminated by a novel pulse sequence, RASER (rapid acquisition by sequential excitation and refocusing) (Chamberlain et al., 2007), that can generate functional maps. This is accomplished because RASER acquired signals are purely and perfectly T(2) weighted, without any T(2)*-effects that are inherent in the other image acquisition schemes employed to date. T(2)-weighted fMRI sequences are also more specific to the site of neuronal activity at ultrahigh magnetic fields than T(2)*-variations since they are dominated by signal components originating from the tissue in the capillary bed. The RASER based fMRI response is quantified; it is shown to have an inherently less noisy time series and to provide fMRI in brain regions, such as the orbitofrontal cortex, which are challenging to image with conventional techniques. PMID:20699123

Goerke, Ute; Garwood, Michael; Ugurbil, Kamil

2010-08-08

39

Magnetic resonance imaging and spectroscopy  

SciTech Connect

This book contains 17 selections. Some of the chapter titles are: Basic Principles of Magnetic Resonance Imaging;Evaluation of Demyelinating Diseases;Respiratory Gating in Magnetic Resonance Imaging;Magnetic Resonance Imaging of the Abdomen;Contrast Agents in Magnetic Resonance Imaging;and Economic Considerations in Magnetic Resonance Imaging.

Mettler, F.A.; Muroff, L.R.; Kulkarni, M.V.

1986-01-01

40

Other magnetic resonance imaging techniques.  

PubMed

Relatively new developments in MRI, such as functional MRI (fMRI), magnetic resonance spectroscopy (MRS) and diffusion tensor imaging (DTI) are rapidly developing into imaging modalities that will become clinically available in the near future. They have in common that their signal is somewhat easier to interpret than structural MRI: fMRI mirrors excess cerebral blood flow, in many cases representing brain activity, MRS gives the average volume concentrations of specific chemical compounds, and DTI reflects "directedness" of micro-anatomical structures, of particular use in white matter where fiber bundle disruption can be detected with great sensitivity. While structural changes in MRI have been disappointing in giving a diagnosis of sufficient sensitivity and specificity, these newer methods hold out hope for elucidating pathological changes and differentiating patient groups more rigorously. This paper summarizes promising research results that will yet have to be translated into real life clinical studies in larger groups of patients (e.g. memory clinic patients). Where available, we have tried to summarize results comparing different types of dementia. PMID:21843379

Ebmeier, Klaus P; Filippini, Nicola; Heise, Verena; Sexton, Claire E

2011-09-01

41

Versatile Magnetic Resonance Spectrometer  

Microsoft Academic Search

A Pound-Knight-Watkins marginal oscillator has been modified by the addition of a vibrating capacitor in parallel with the tuning capacitor to produce a simple circuit which may be used to observe paramagnetic resonance at low fields, nuclear magnetic resonance, and nuclear quadrupole resonance. Suggestions are made as to the type of information which may be obtained in an undergraduate laboratory

J. A. Cowen; W. H. Tanttila

1958-01-01

42

VERSATILE MAGNETIC RESONANCE SPECTROMETER  

Microsoft Academic Search

A Pound-Knight-Watkins marginal osciliator was modified by the addition ; of a vibrating capacitor in parallel with the tuning capacitor to produce a ; simple circuit which may be used to observe paramagnetic resonance at low fields, ; nuclear magnetic resonance, and nuclear quadrupole resonance. Suggestions are ; mnde as to the type of information which may be obtained in

J. A. Cowen; W. H. Tanttila

1958-01-01

43

Brain activation during manipulation of the myoelectric prosthetic hand: a functional magnetic resonance imaging study  

Microsoft Academic Search

Neuroimaging data, particularly functional magnetic resonance imaging (fMRI) findings, have not been reported in users of the myoelectric or electromyographic (EMG) prosthetic hand. We developed a virtual EMG prosthetic hand system to eliminate mutual signal noise interference between fMRI imaging and the EMG prosthesis. We used fMRI to localize activation in the human brain during manipulation of the virtual EMG

Masaharu Maruishi; Yoshiyuki Tanaka; Hiroyuki Muranaka; Toshio Tsuji; Yoshiaki Ozawa; Satoshi Imaizumi; Makoto Miyatani; Junichiro Kawahara

2004-01-01

44

Linear Systems Analysis of Functional Magnetic Resonance Imaging in Human V1  

Microsoft Academic Search

The linear transform model of functional magnetic resonance imaging (fMRI) hypothesizes that fMRI responses are propor- tional to local average neural activity averaged over a period of time. This work reports results from three empirical tests that support this hypothesis. First, fMRI responses in human pri- mary visual cortex (V1) depend separably on stimulus timing and stimulus contrast. Second, responses

Geoffrey M. Boynton; Stephen A. Engel; Gary H. Glover; David J. Heeger

1996-01-01

45

Pediatric functional magnetic resonance neuroimaging: tactics for encouraging task compliance  

Microsoft Academic Search

Background  Neuroimaging technology has afforded advances in our understanding of normal and pathological brain function and development\\u000a in children and adolescents. However, noncompliance involving the inability to remain in the magnetic resonance imaging (MRI)\\u000a scanner to complete tasks is one common and significant problem. Task noncompliance is an especially significant problem in\\u000a pediatric functional magnetic resonance imaging (fMRI) research because increases

Michael W Schlund; Michael F Cataldo; Greg J Siegle; Cecile D Ladouceur; Jennifer S Silk; Erika E Forbes; Ashley McFarland; Satish Iyengar; Ronald E Dahl; Neal D Ryan

2011-01-01

46

Brain Mapping in Sedated Infants and Young Children with Passive-Functional Magnetic Resonance Imaging  

Microsoft Academic Search

Functional magnetic resonance imaging (fMRI) in pediatric patients presents a unique set of problems due to the need for patient compliance, the frequent need for sedation and an early developmental status. A new method for using fMRI in sedated infants and young children is presented using passive stimuli focused on visual, sensorimotor and language functions. All of these stimuli are

M. M. Souweidane; K. H. S. Kim; R. McDowall; M. I. Ruge; E. Lis; G. Krol; J. Hirsch

1999-01-01

47

Biology and therapy of fibromyalgia. Functional magnetic resonance imaging findings in fibromyalgia  

Microsoft Academic Search

Techniques in neuroimaging such as functional magnetic resonance imaging (fMRI) have helped to provide insights into the role of supraspinal mechanisms in pain perception. This review focuses on studies that have applied fMRI in an attempt to gain a better understanding of the mechanisms involved in the processing of pain associated with fibromyalgia. This article provides an overview of the

David A Williams; Richard H Gracely

2006-01-01

48

Magnetic resonance imaging  

SciTech Connect

This book contains the following four major sections: physics and chemistry, relaxation/relaxometry, instrumentation, research areas. The authors discuss instrumentation and technical approaches in magnetic resonance (MR) imaging.

Partain, C.L.; Price, R.R.; Patton, J.A.; Kulkarni, M.V.; James, A.E.

1988-01-01

49

Magnetic Resonance Imaging (MRI).  

National Technical Information Service (NTIS)

Magnetic resonance imaging (MRI) is a method of graphically representing the distribution of water and other hydrogen-rich molecules in the human body. Imaging parameters are complex. Although MR images may demonstrate anatomy as do conventional radiograp...

E. Feigenbaum

1985-01-01

50

Nuclear magnetic resonance gyroscope  

SciTech Connect

A nuclear magnetic resonance gyro using two nuclear magnetic resonance gases, preferably xenon 129 and xenon 131, together with two alkaline metal vapors, preferably rubidium, potassium or cesium, one of the two alkaline metal vapors being pumped by light which has the wavelength of that alkaline metal vapor, and the other alkaline vapor being illuminated by light which has the wavelength of that other alkaline vapor.

Grover, B.C.

1984-02-07

51

Gender effects on odor-stimulated functional magnetic resonance imaging  

Microsoft Academic Search

On standardized tests of odor identification and odor detection, women tend to score better than men at nearly all age groups. We sought to determine if these findings would translate to differences between the sexes in the volume of activated brain when odors are presented to subjects as the stimulants for functional magnetic resonance imaging (FMRI) experiments. The activation maps

David M. Yousem; Joseph A. Maldjian; Faez Siddiqi; Thomas Hummel; David C. Alsop; Rena J. Geckle; Warren B. Bilker; Richard L. Doty

1999-01-01

52

Human Brain Language Areas Identified by Functional Magnetic Resonance Imaging  

Microsoft Academic Search

Functional magnetic resonance imaging (FMRI) was used to identify candidate language processing areas in the intact hu- man brain. Language was defined broadly to include both phonological and lexical-semantic functions and to exclude sensory, motor, and general executive functions. The language activation task required phonetic and semantic analysis of aurally presented words and was compared with a control task involving

Jeffrey R. Binder; Julie A. Frost; Thomas A. Hammeke; Robert W. Cox; Stephen M. Rao; Thomas Prieto

1997-01-01

53

Magnetic Resonance Imaging  

NSDL National Science Digital Library

This lesson ties the preceding lessons together and brings students back to the grand challenge question on MRI safety. During this lesson, students focus on the logistics of magnetic resonance imaging as well as the MRI hardware. Students can then integrate this knowledge with their acquired knowledge on magnetic fields to solve the challenge question.

VU Bioengineering RET Program, School of Engineering,

54

Nuclear Magnetic Resonance.  

National Technical Information Service (NTIS)

Nuclear Magnetic Resonance (NMR) is a new technique which has been introduced into the medical diagnostic imaging field. NMR is a method of imaging the body by exposing it to low-energy magnetic and radio-frequency fields. This process yields bio-chemical...

D. Watkins N. Netherton

1983-01-01

55

Functional magnetic resonance imaging in acute unilateral optic neuritis.  

PubMed

Despite good clinical criteria for diagnosing optic neuritis (ON), only a few techniques can precisely assess its impact on visual brain function. The authors studied whether functional magnetic resonance imaging (fMRI) of visual activation reliably reflects the cerebral consequences of acute unilateral ON, and how fMRI correlates with clinical function and visual evoked potentials (VEPs). Twenty ON patients, before and after steroid treatment, were compared to 20 controls. Each eye was stimulated separately with a checkerboard pattern reversing at 1, 2, 4, and 8 Hz. VEPs were recorded the same day. Initially, affected eye responses differed significantly from those of unaffected counterparts and controls in 12 patients. Post hoc classification by fMRI criteria was correct in approximately 85%. fMRI and VEP response parameters (as well as visual acuity) correlated significantly. The higher stimulation frequencies yielded greater fMRI responses from unaffected eyes, but not from affected eyes, in controls. The fMRI responses were quantifiable in every subject, whereas in 11 ON eyes, no VEPs were obtained during the acute stage. The authors conclude that fMRI is sensitive to the cerebral response alteration during ON and might therefore contribute to evaluating the temporal evolution of the visual functional deficit during recovery or therapy. PMID:12380481

Russ, Michael O; Cleff, Ulrich; Lanfermann, Heinrich; Schalnus, Rainer; Enzensberger, Wolfgang; Kleinschmidt, Andreas

2002-10-01

56

Functional Magnetic Resonance Imaging for Language Mapping in Temporal Lobe Epilepsy  

PubMed Central

Functional magnetic resonance imaging (fMRI) is a noninvasive technique that is increasingly used to understand the cerebral cortical networks and organizations. In this paper, we describe the role of fMRI for mapping language networks in the presurgical workup of patients with medically intractable temporal lobe epilepsy (TLE). Studies comparing fMRI with the intracarotid sodium amobarbital (Wada) test and fMRI with intraoperative cortical stimulation mapping for language lateralization and/or localization in medically intractable TLE are discussed.

Wang, An; Peters, Terry M.; de Ribaupierre, Sandrine; Mirsattari, Seyed M.

2012-01-01

57

Magnetic Field Shift due to Mechanical Vibration in Functional Magnetic Resonance Imaging  

PubMed Central

Mechanical vibrations of the gradient coil system during readout in echo-planar imaging (EPI) can increase the temperature of the gradient system, and alter the magnetic field distribution during functional magnetic resonance imaging (fMRI). This effect is enhanced by resonant modes of vibrations and results in apparent motion along the phase encoding direction in fMRI studies. The magnetic field drift was quantified during EPI, by monitoring the resonance frequency interleaved with the EPI acquisition, and a novel method is proposed to correct the apparent motion. The knowledge on the frequency drift over time was used to correct the phase of the k-space EPI dataset. Since the resonance frequency changes very slowly over time, two measurements of the resonance frequency, immediately before and after the EPI acquisition, are sufficient to remove the field drift effects from fMRI time series. The frequency drift correction method was tested “in vivo” and compared to the standard image realignment method. The proposed method efficiently corrects spurious motion due to magnetic field drifts during fMRI.

Foerster, Bernd U.; Tomasi, Dardo; Caparelli, Elisabeth C.

2008-01-01

58

Noninvasive assessment of the injured human spinal cord by means of functional magnetic resonance imaging  

Microsoft Academic Search

Study design: A magnetic resonance imaging technique that enables indirect detection of neuronal activity has been developed for the spinal cord. In the present study, this method, spinal functional magnetic resonance imaging (fMRI), is applied to the first study of the injured spinal cord, with the goal of better clinical assessment of the entire cord.Objectives: The objectives of this project

P W Stroman; J Kornelsen; A Bergman; V Krause; K Ethans; K L Malisza; B Tomanek

2004-01-01

59

Resonant and non-resonant magnetic scattering  

SciTech Connect

The tunability and the polarization of synchrotron radiation open upon new possibilities for the study of magnetism. Studies on magnetic materials performed at the National Synchrotron Light Source are reviewed, and thy fall into four areas: structure, evolution of magnetic order, separation of L and S, and resonance effects. In the vicinity of atomic absorption edges, the Faraday effect, magnetic circular dichroism, and resonant magnetic scattering are all related resonance effects which measure the spin polarized density of states. The production and analysis of polarized beams are discussed in the context of the study of magnetism with synchrotron radiation.

McWhan, D.B.; Hastings, J.B.; Kao, C.C.; Siddons, D.P.

1991-12-31

60

Resonant and non-resonant magnetic scattering  

SciTech Connect

The tunability and the polarization of synchrotron radiation open upon new possibilities for the study of magnetism. Studies on magnetic materials performed at the National Synchrotron Light Source are reviewed, and thy fall into four areas: structure, evolution of magnetic order, separation of L and S, and resonance effects. In the vicinity of atomic absorption edges, the Faraday effect, magnetic circular dichroism, and resonant magnetic scattering are all related resonance effects which measure the spin polarized density of states. The production and analysis of polarized beams are discussed in the context of the study of magnetism with synchrotron radiation.

McWhan, D.B.; Hastings, J.B.; Kao, C.C.; Siddons, D.P.

1991-01-01

61

Clinical magnetic resonance imaging  

SciTech Connect

This book presents clinical applications of magnetic resonance imaging with a strong clinical orientation. Covers technique, instrumentation, and contrast agents. Describes MRI of the neck, brain, heart, spine, TMJ and orbit, chest abdomen, pelvis, and the joints. Also includes a high field atlas of the central nervous system.

Brady, T.J.; Edelman, R.R.

1988-01-01

62

Magnetic Resonance Annual, 1985  

SciTech Connect

The inaugural volume of Magnetic Resonance Annual includes reviews of MRI of the posterior fossa, cerebral neoplasms, and the cardiovascular and genitourinary systems. A chapter on contrast materials outlines the mechanisms of paramagnetic contrast enhancement and highlights several promising contrast agents.

Kressel, H.Y.

1985-01-01

63

Magnetic resonance fingerprinting.  

PubMed

Magnetic resonance is an exceptionally powerful and versatile measurement technique. The basic structure of a magnetic resonance experiment has remained largely unchanged for almost 50?years, being mainly restricted to the qualitative probing of only a limited set of the properties that can in principle be accessed by this technique. Here we introduce an approach to data acquisition, post-processing and visualization--which we term 'magnetic resonance fingerprinting' (MRF)--that permits the simultaneous non-invasive quantification of multiple important properties of a material or tissue. MRF thus provides an alternative way to quantitatively detect and analyse complex changes that can represent physical alterations of a substance or early indicators of disease. MRF can also be used to identify the presence of a specific target material or tissue, which will increase the sensitivity, specificity and speed of a magnetic resonance study, and potentially lead to new diagnostic testing methodologies. When paired with an appropriate pattern-recognition algorithm, MRF inherently suppresses measurement errors and can thus improve measurement accuracy. PMID:23486058

Ma, Dan; Gulani, Vikas; Seiberlich, Nicole; Liu, Kecheng; Sunshine, Jeffrey L; Duerk, Jeffrey L; Griswold, Mark A

2013-03-14

64

Nuclear magnetic resonance gyroscopes  

Microsoft Academic Search

Nuclear magnetic resonance gyroscopes (NMRGs) detect rotation as a shift in the Larmor precession frequency of nuclear spins. A review of the open literature on NMRGs is presented, which includes an introduction to the spectroscopic techniques that enable NMRGs and a discussion of the design details for several specific NMRGs that have been built.

E. A. Donley

2010-01-01

65

The effect of musical training on the neural correlates of math processing: a functional magnetic resonance imaging study in humans  

Microsoft Academic Search

The neural correlates of the previously hypothesized link between formal musical training and mathematics performance are investigated using functional magnetic resonance imaging (fMRI). FMRI was performed on fifteen normal adults, seven with musical training since early childhood, and eight without, while they mentally added and subtracted fractions. Musical training was associated with increased activation in the left fusiform gyrus and

Vincent J. Schmithorst; Scott K. Holland

2004-01-01

66

Postnatal Changes in Functional Activities of the Pig’s Brain: A Combined Functional Magnetic Resonance Imaging and Immunohistochemical Study  

Microsoft Academic Search

Developmental changes in brain activation after pain stimulation and after passive movement of the hind paw were assessed by functional magnetic resonance imaging (fMRI) in pigs of postnatal ages 2, 4 and 6 months. Response patterns were correlated with histological maturation parameters. At 2 months, fMRI failed to detect brain activation after pain stimulation and revealed weak, but widespread activation

Marong Fang; Dietrich E. Lorke; Jicheng Li; Xiangyang Gong; Jason C. C. Yew; D. T. Yew

2005-01-01

67

High field magnetic resonance  

US Patent & Trademark Office Database

A magnetic resonance system is disclosed. The system includes a transceiver having a multichannel receiver and a multichannel transmitter, where each channel of the transmitter is configured for independent selection of frequency, phase, time, space, and magnitude, and each channel of the receiver is configured for independent selection of space, time, frequency, phase and gain. The system also includes a magnetic resonance coil having a plurality of current elements, with each element coupled in one to one relation with a channel of the receiver and a channel of the transmitter. The system further includes a processor coupled to the transceiver, such that the processor is configured to execute instructions to control a current in each element and to perform a non-linear algorithm to shim the coil.

2010-09-21

68

Nuclear magnetic resonance contrast agents  

DOEpatents

This invention relates to the field of nuclear magnetic resonance imaging and nuclear magnetic resonance spectroscopy, also known simply as magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS). MRI and MRS are particularly useful in medical research and diagnosis. MRI may be used in addition to x-ray imaging. This invention concerns a family of contrast agents for use in magnetic resonance imaging and a method of enhancing the contrast of magnetic resonance images of an object by incorporating a contrast agent of this invention into the object prior to forming the images or during formation of the images. A contrast agent of this invention is a paramagnetic lanthanide hexaazamacrocyclic molecule, where a basic example has the formula LnC{sub 16}H{sub 14}N{sub 6}. Important applications of the invention are in medical diagnosis, treatment, and research, where images of portions of a human body are formed by means of magnetic resonance techniques. 2 figs.

Smith, P.H.; Brainard, J.R.; Jarvinen, G.D.; Ryan, R.R.

1989-01-24

69

C-C4-01: Functional Magnetic Resonance Imaging (fMRI) and Diffusion Tensor Imaging (DTI): An Efficient, Non-invasive Alternative to Conventional Pre-surgical Planning in Neurosurgery  

PubMed Central

Background: Neurosurgical intervention often requires pre-surgical or intra-operative planning/mapping techniques that are invasive. For example, prior to temporal lobectomy for intractable epilepsy, patients often undergo a WADA test which involves anesthetizing one hemisphere of the brain at a time to localize memory and language functions. For other neurosurgical cases, electrophysiological intra-operative mapping of the cortex is often used during tumor resections proximal to eloquent cortex, or for localization of specific cortex (i.e., motor) when placing neurostimulators (e.g., for pain management). Less common, but emerging as a noninvasive planning tool, fMRI was designated in three CPT codes for pre-surgical planning purposes. Here, we examined the effectiveness of fMRI and DTI by comparing fMRI data to WADA test results (for epilepsy patients) and electrophysiological recordings (for tumor resections and motor cortex stimulator placement). We also examine the utility of DTI in the context of surgical intervention. Methods: We examined 8 intractable temporal lobe epilepsy (TLE) patients (5 males, 3 females; 6 left TLE, 2 right TLE) who underwent both WADA testing and fMRI language mapping for pre-surgical planning purposes, 1 tumor resection case in which the tumor was near the motor cortex and intra-operative electrophysiological mapping was employed, and 1 motor cortex neurostimulator case in which electrophysiological mapping was performed. All patients were enrolled in IRB-approved studies. FMRI data (language or motor) was obtained prior to surgical intervention and maps were used intra-operatively using BrainLab. Results: In all 8 epilepsy cases, language mapping data was concordant between fMRI and WADA test results. However, fMRI mapping allowed for discrete, focal localization of regions involved in language processes whereas WADA testing only delineated hemispheric dominance. In the tumor resection case, fMRI data was consistent with electrophysiological recordings obtained intra-operatively. Finally, fMRI data was used as the primary localization technique for the motor cortex neurostimulator, and confirmed with electrophysiological recordings. Conclusions: Here, we demonstrate the effectiveness of fMRI as a powerful pre-surgical planning tool that has the potential to replace invasive and costly conventional methods. FMRI maps can easily be uploaded and used intra-operatively during stereotactic neurosurgery for accurate localization of complex brain functions.

Robinson, Jennifer; Kirmani, Batool; Sanghera, Manjit; Phillips-Sabol, Jacqueline; Cruz, Daniel; Wright, Charles; Friehs, Gerhard

2010-01-01

70

Pediatric functional magnetic resonance neuroimaging: tactics for encouraging task compliance  

PubMed Central

Background Neuroimaging technology has afforded advances in our understanding of normal and pathological brain function and development in children and adolescents. However, noncompliance involving the inability to remain in the magnetic resonance imaging (MRI) scanner to complete tasks is one common and significant problem. Task noncompliance is an especially significant problem in pediatric functional magnetic resonance imaging (fMRI) research because increases in noncompliance produces a greater risk that a study sample will not be representative of the study population. Method In this preliminary investigation, we describe the development and application of an approach for increasing the number of fMRI tasks children complete during neuroimaging. Twenty-eight healthy children ages 9-13 years participated. Generalization of the approach was examined in additional fMRI and event-related potential investigations with children at risk for depression, children with anxiety and children with depression (N = 120). Essential features of the approach include a preference assessment for identifying multiple individualized rewards, increasing reinforcement rates during imaging by pairing tasks with chosen rewards and presenting a visual 'road map' listing tasks, rewards and current progress. Results Our results showing a higher percentage of fMRI task completion by healthy children provides proof of concept data for the recommended tactics. Additional support was provided by results showing our approach generalized to several additional fMRI and event-related potential investigations and clinical populations. Discussion We proposed that some forms of task noncompliance may emerge from less than optimal reward protocols. While our findings may not directly support the effectiveness of the multiple reward compliance protocol, increased attention to how rewards are selected and delivered may aid cooperation with completing fMRI tasks Conclusion The proposed approach contributes to the pediatric neuroimaging literature by providing a useful way to conceptualize and measure task noncompliance and by providing simple cost effective tactics for improving the effectiveness of common reward-based protocols.

2011-01-01

71

Magnetic Resonance Facility (Fact Sheet)  

SciTech Connect

This fact sheet provides information about Magnetic Resonance Facility capabilities and applications at NREL's National Bioenergy Center. Liquid and solid-state analysis capability for a variety of biomass, photovoltaic, and materials characterization applications across NREL. NREL scientists analyze solid and liquid samples on three nuclear magnetic resonance (NMR) spectrometers as well as an electron paramagnetic resonance (EPR) spectrometer.

Not Available

2012-03-01

72

Multimodal Magnetic Resonance Imaging for Brain Disorders: Advances and Perspectives  

Microsoft Academic Search

Modern brain imaging technologies play essential roles in our understanding of brain information processing and the mechanisms\\u000a of brain disorders. Magnetic Resonance Imaging (MRI) and Diffusion Tensor Imaging (DTI) can image the anatomy and structure\\u000a of the brain. In addition, functional MRI (fMRI) can identify active regions, patterns of functional connectivities and functional\\u000a networks during either tasks that are specifically

Tianzi Jiang; Yong Liu; Feng Shi; Ni Shu; Bing Liu; Jiefeng Jiang; Yuan Zhou

2008-01-01

73

Exploiting Temporal Information in Functional Magnetic Resonance Imaging Brain Data  

Microsoft Academic Search

Functional Magnetic Resonance Imaging(fMRI) has enabled scientists to look into the active human brain, leading to a flood of new data, thus encouraging the development of new data analysis methods. In this paper, we contribute a comprehensive framework for spatial and tem- poral exploration of fMRI data, and apply it to a challenging case study: separating drug addicted subjects from

Lei Zhang; Dimitris Samaras; Dardo Tomasi; Nelly Alia-klein; Lisa Cottone; Andreana Leskovjan; Nora D. Volkow; Rita Goldstein

2005-01-01

74

[Myelin and nuclear magnetic resonance].  

PubMed

MRI is one of the most important tools for the investigation of white matter diseases of the central nervous system. Other techniques based on the magnetic resonance phenomena (magnetization transfer imaging, diffusion imaging, magnetic resonance spectroscopy) have joined MRI to better caracterize certain diseases, understand their pathophysiology and follow their evolution. PMID:18033031

Tourbah, A; Dormont, D; Galanaud, D; Sedel, F; Lyon-Caen, O

2007-10-01

75

Brain Activity during Simulated Deception: An Event-Related Functional Magnetic Resonance Study  

Microsoft Academic Search

TheGuilty Knowledge Test (GKT) has been used extensively to model deception. An association between the brain evoked response potentials and lying on the GKT suggests that deception may be associated with changes in other measures of brain activity such as regional blood flow that could be anatomically localized with event-related functional magnetic resonance imaging (fMRI). Blood oxygenation level-dependent fMRI contrasts

D. D. Langleben; L. Schroeder; J. A. Maldjian; R. C. Gur; S. McDonald; J. D. Ragland; C. P. O'Brien; A. R. Childress

2002-01-01

76

Multifractal analysis of blood oxygen level dependent functional magnetic resonance imaging  

Microsoft Academic Search

The aim of this work is to propose a multifractal analysis method for Multifractal Detrended Fluctuation analysis (MF-DFA) of Blood Oxygen Level Dependent (BOLD) functional Magnetic Resonance Imaging (fMRI). The fMRI signals exhibit a 1\\/f power spectrum, hence their structure has self-similarity and long memory, being usually successfully analyzed by different fractal analysis methods without a previous knowledge of haemodynamic

Catarina Runa Miranda; Filipe Soares; Ines Sousa; Filipe Janela; Mario Forjaz Secca

2011-01-01

77

Functional magnetic resonance imaging activation detection: fuzzy cluster analysis in wavelet and multiwavelet domains  

Microsoft Academic Search

PURPOSE: To present novel feature spaces, based on multiscale decompositions obtained by scalar wavelet and multiwavelet transforms, to remedy problems associated with high dimension of functional magnetic resonance imaging (fMRI) time series (when they are used directly in clustering algorithms) and their poor signal-to-noise ratio (SNR) that limits accurate classification of fMRI time series according to their activation contents. MATERIALS

H. Jahanian; H. Soltanian-Zadeh; G. A. Hossein-Zadeh

2005-01-01

78

Functional magnetic resonance imaging of internal source monitoring in schizophrenia: Recognition with and without recollection  

Microsoft Academic Search

Patients with schizophrenia tend to have impaired source monitoring and intact item recognition, suggesting an over-reliance of familiarity effects. We previously demonstrated that providing patients with a levels-of-processing (LOP) semantic encoding strategy normalized source monitoring. The current blood-oxygen-level-dependent (BOLD) functional magnetic resonance imaging (fMRI) study tests the hypothesis that patients will have abnormally increased fronto-temporal activation despite intact performance. fMRI

J. Daniel Ragland; Jeffrey N. Valdez; James Loughead; Ruben C. Gur; Raquel E. Gur

2006-01-01

79

Detecting functional magnetic resonance imaging activation in white matter: Interhemispheric transfer across the corpus callosum  

Microsoft Academic Search

Background  It is generally believed that activation in functional magnetic resonance imaging (fMRI) is restricted to gray matter. Despite\\u000a this, a number of studies have reported white matter activation, particularly when the corpus callosum is targeted using interhemispheric\\u000a transfer tasks. These findings suggest that fMRI signals may not be neatly confined to gray matter tissue. In the current\\u000a experiment, 4 T

Erin L Mazerolle; Ryan CN D'Arcy; Steven D Beyea

2008-01-01

80

Functional magnetic resonance imaging sequential-finger movement activation differentiating good and poor writers  

Microsoft Academic Search

Good and poor fifth-grade writers differed, after controlling for multiple comparisons, in 42 brain regions on group maps and then individual brain analyses for functional magnetic resonance imaging (fMRI) contrast between tapping adjacent fingers sequentially and same finger repeatedly. Of these, 11 regions were correlated with both handwriting and spelling (transcription). Gender differences on the fMRI contrast, with girls more

Todd L. Richards; Virginia W. Berninger; Pat Stock; Leah Altemeier; Pamala Trivedi; Ken Maravilla

2009-01-01

81

The Visible Brain: Confidentiality and Privacy Implications of Functional Magnetic Resonance Imaging  

Microsoft Academic Search

Functional magnetic resonance imaging (fMRI) has built on a number of technologies, including electroencephalography, magnetoencephalography, positron emission tomography, and single-photon emission computed tomography, to become one of the decade’s most powerful tools for mapping sensory, motor, and cognitive function. Scientists also are using fMRI to study the neural correlates of a range of conditions, characteristics, and social behaviors, including severe

Stacey A. Tovino

2006-01-01

82

Magnetic resonance enterography.  

PubMed

Magnetic resonance (MR) enterography is a targeted examination of the gastrointestinal tract, particularly the small intestine, without nasojejunal intubation (in which case it is referred to as MR enteroclysis). Until recently, MR imaging of the small bowel could not reliably compete with the high-quality small bowel images generated by computed tomography (CT). Now, however, MR enterography is not only a feasible alternative to CT, but may provide superior diagnostic information, specifically with regard to differentiating active, inflammatory disease from chronic, fibrostenotic disease. MR enterography is no longer merely adequate and radiation-free; it is an essential part of the imaging armamentarium. PMID:23182510

Grand, David J; Beland, Michael; Harris, Adam

2013-01-01

83

nuclear magnetic resonance gyroscope  

SciTech Connect

A nuclear magnetic resonance gyroscope which derives angular rotation thereof from the phases of precessing nuclear moments utilizes a single-resonance cell situated in the center of a uniform DC magnetic field. The field is generated by current flow through a circular array of coils between parallel plates. It also utilizes a pump and read-out beam and associated electronics for signal processing and control. Encapsulated in the cell for sensing rotation are odd isotopes of Mercury Hg/sup 199/ and Hg/sup 201/. Unpolarized intensity modulated light from a pump lamp is directed by lenses to a linear polarizer, quarter wave plate combination producing circularly polarized light. The circularly polarized light is reflected by a mirror to the cell transverse to the field for optical pumping of the isotopes. Unpolarized light from a readout lamp is directed by lenses to another linear polarizer. The linearly polarized light is reflected by another mirror to the cell transverse to the field and orthogonal to the pump lamp light. The linear light after transversing the cell strikes an analyzer where it is converted to an intensity-modulated light. The modulated light is detected by a photodiode processed and utilized as feedback to control the field and pump lamp excitation and readout of angular displacement.

Karwacki, F. A.; Griffin, J.

1985-04-02

84

Biology and therapy of fibromyalgia. Functional magnetic resonance imaging findings in fibromyalgia  

PubMed Central

Techniques in neuroimaging such as functional magnetic resonance imaging (fMRI) have helped to provide insights into the role of supraspinal mechanisms in pain perception. This review focuses on studies that have applied fMRI in an attempt to gain a better understanding of the mechanisms involved in the processing of pain associated with fibromyalgia. This article provides an overview of the nociceptive system as it functions normally, reviews functional brain imaging methods, and integrates the existing literature utilizing fMRI to study central pain mechanisms in fibromyalgia.

Williams, David A; Gracely, Richard H

2006-01-01

85

Nuclear Magnetic Resonance (NMR) Guidelines.  

National Technical Information Service (NTIS)

Nuclear Magnetic Resonance (NMR) is a medical diagnostic imaging technique that applies the atomic principles of magnetic spin to visualize and analyze disease states in bodily tissues. NMR differs from the radiological devices in that (a) it does not uti...

R. Halpern

1983-01-01

86

Magnetic resonance cell  

SciTech Connect

There is disclosed a nuclear magnetic alignment device for use in a nuclear magnetic resonance gyroscope and the like. One embodiment includes a container for gas having a layer of rubidium hydride on its inner surface. The container comprising a spherical portion and a tip portion, is rotationally symmetric about an axis of symmetry. Enclosed within the container is a nuclear moment gas having a nuclear electric quadrupole moment, such as xenon-131, and an optically pumpable substance, such as rubidium. A portion of the rubidium is a vapor. The remainder is a condensed pellet which is deposited in the tip of the container such that the pellet is also rotationally symmetric about the axis of symmetry of the container. A layer of rubidium hydride is deposited on the inner surface of the container. The device further includes means for orienting the symmetry axis of the container at an angle to an applied magnetic field such that the relaxation time constant of the aligned nuclear moment gas is substantially at a maximum.

Kwon, T.M.; Volk, C.H.

1984-05-01

87

Magnetic Field Issues in Magnetic Resonance Imaging  

Microsoft Academic Search

Advances in Magnetic Resonance Imaging depend on the capability of the available hardware. Specifically, for the main magnet configuration, using derivative constraints, we can create a static magnetic field with reduced levels of inhomogeneity over a prescribed imaging volume. In the gradient coil, the entire design for the axial elliptical coil, and the mathematical foundation for the transverse elliptical coil

Labros Spiridon Petropoulos

1993-01-01

88

Secondary resonance magnetic force microscopy  

NASA Astrophysics Data System (ADS)

In this study, we have developed secondary resonance magnetic force microscopy (SR-MFM) for imaging alternating magnetic fields from a sample surface at the secondary resonant frequency of the magnetic cantilever at the same time as the topographic image. SR-MFM images of alternating magnetic fields diverging from the main pole in a driving perpendicular magnetic recording head are presented, and the divergence and convergence of the fields are discussed. The spatial resolution of SR-MFM is estimated to be 18 nm this is 2.5 times smaller than that of conventional MFM.

Tanaka, Suguru; Azuma, Yasuo; Majima, Yutaka

2012-04-01

89

MR-Eyetracker: a new method for eye movement recording in functional magnetic resonance imaging  

Microsoft Academic Search

We present a method for recording saccadic and pursuit eye movements in the magnetic resonance tomograph designed for visual\\u000a functional magnetic resonance imaging (fMRI) experiments. To reliably classify brain areas as pursuit or saccade related it\\u000a is important to carefully measure the actual eye movements. For this purpose, infrared light, created outside the scanner\\u000a by light-emitting diodes (LEDs), is guided

H. Kimmig; M. W. Greenlee; F. Huethe; T. Mergner

1999-01-01

90

Field Concentrator Based Resonant Magnetic Sensor  

Microsoft Academic Search

A novel resonant magnetic sensor based on the combination of a mechanical resonator and a magnetic field concentrator with two gaps is reported. In contrast to previous Lorentz force based resonant magnetic sensors, a high sensitivity is achieved without modulated driving current and complex feedback electronics. Furthermore, compared to magnetic moment based resonant magnetic sensors, the new concept requires no

S. Brugger; P. Simon; O. Paul

2006-01-01

91

Quantitative spatial comparison of diffuse optical imaging with blood oxygen level-dependent and arterial spin labeling-based functional magnetic resonance imaging  

Microsoft Academic Search

Akin to functional magnetic resonance imaging fMRI, dif- fuse optical imaging DOI is a noninvasive method for measuring localized changes in hemoglobin levels within the brain. When com- bined with fMRI methods, multimodality approaches could offer an integrated perspective on the biophysics, anatomy, and physiology underlying each of the imaging modalities. Vital to the correct inter- pretation of such studies,

Theodore J. Huppert; Rick D. Hoge; Anders M. Dale; Maria A. Franceschini; David A. Boas

2006-01-01

92

Simple and Inexpensive Classroom Demonstrations of Nuclear Magnetic Resonance and Magnetic Resonance Imaging.  

ERIC Educational Resources Information Center

Describes a set of simple, inexpensive, classical demonstrations of nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) principles that illustrate the resonance condition associated with magnetic dipoles and the dependence of the resonance frequency on environment. (WRM)

Olson, Joel A.; Nordell, Karen J.; Chesnik, Marla A.; Landis, Clark R.; Ellis, Arthur B.; Rzchowski, M. S.; Condren, S. Michael; Lisensky, George C.

2000-01-01

93

Nuclear magnetic resonance contrast agents  

DOEpatents

A family of contrast agents for use in magnetic resonance imaging and a method of enhancing the contrast of magnetic resonance images of an object by incorporating a contrast agent of this invention into the object prior to forming the images or during formation of the images. A contrast agent of this invention is a paramagnetic lanthanide hexaazamacrocyclic molecule, where a basic example has the formula LnC{sub 16}H{sub 14}N{sub 6}. Important applications of the invention are in medical diagnosis, treatment, and research, where images of portions of a human body are formed by means of magnetic resonance techniques. 10 figs.

Smith, P.H.; Brainard, J.R.; Jarvinen, G.D.; Ryan, R.R.

1997-12-30

94

Nuclear magnetic resonance contrast agents  

DOEpatents

A family of contrast agents for use in magnetic resonance imaging and a method of enhancing the contrast of magnetic resonance images of an object by incorporating a contrast agent of this invention into the object prior to forming the images or during formation of the images. A contrast agent of this invention is a paramagnetic lanthanide hexaazamacrocyclic molecule, where a basic example has the formula LnC.sub.16 H.sub.14 N.sub.6. Important applications of the invention are in medical diagnosis, treatment, and research, where images of portions of a human body are formed by means of magnetic resonance techniques.

Smith, Paul H. (Los Alamos, NM); Brainard, James R. (Los Alamos, NM); Jarvinen, Gordon D. (Los Alamos, NM); Ryan, Robert R. (Los Alamos, NM)

1997-01-01

95

Nuclear magnetic resonance spectrometry  

SciTech Connect

This review covers the published literature from July 1983 to August 1985 although some citations of other work are also included. As noted in earlier reviews it is impossible to summarize 2 years of NMR literature in so short a space. However, it is hoped that the books, reviews, and various citations will be a useful guide to the reader. The publication Spectroscopy (PO Box 50, Springfield, OR 97477; H. W. Lafferty, Ed.) has recently commenced and promises to be of interest and utility in various areas of spectroscopy, including NMR. Noninvasive Medical Imaging, an international journal published by Verlag Chemie GmbH (Federal Republic of Germany) and Reviews of Magnetic Resonance in Medicine published by Pergamon Press cover specialized application of NMR. The American Chemical Society has introduced an audiocassette course on Fourier Transform NMR Spectroscopy. An extensive C13 NMR Data Base has been made available by Science Information Services, Inc., Larchmont, NY, and City Software, Milwaukee, WI has introduced The NMR Simulator for the IBM PC. 342 references, 2 tables.

Wasson, J.R.

1986-04-01

96

Orthopaedic Magnetic Resonance Imaging Challenge  

PubMed Central

Apophyseal avulsion injuries of the hip and pelvis are frequent athletic injuries in children and adolescents, most commonly associated with explosive movement or sprinting. This article details typically encountered apophyseal injuries and their appearance on magnetic resonance imaging.

Kjellin, Ingrid; Stadnick, Michael E.; Awh, Mark H.

2010-01-01

97

Fluorine-19 Nuclear Magnetic Resonance.  

National Technical Information Service (NTIS)

Several series of diadducts of titanium tetrafluoride were studied with high resolution fluorine-19 nuclear magnetic resonance spectroscopy. These consisted of studies with aromatic amine oxides, amides and sulfoxides as bases. Mixed diadducts of TiF4 wit...

R. O. Ragsdale

1971-01-01

98

Consolidation of human memory over decades revealed by functional magnetic resonance imaging  

Microsoft Academic Search

Medial temporal lobe (MTL) lesions typically produce retrograde amnesia characterized by the disproportionate loss of recently acquired memories. Temporally graded memory loss is interpreted traditionally as evidence for a consolidation process guided by the MTL. Here, using functional magnetic resonance imaging (fMRI), we show temporally graded changes in MTL activity in healthy older adults taking a famous faces remote memory

Jane Bowden Gore; Hui Mao; Frank Haist

2001-01-01

99

Research repoft Gender effects on odor-stimulated functional magnetic resonance imaging  

Microsoft Academic Search

On standardized tests of odor identification and odor detection, women tend to score better than men at nearly all age groups. We sought to determine if these findings would translate to differences between the sexes in the volume of activated brain when odors are presented to subjects as the stimulants for functional magnetic resonance imaging (FMRI) experiments. The activation maps

David M. Yousem; Thomas Hummel; David C. Alsop; Rena J. Geckle; Warren B. Bilker; Richard L. Doty

100

A Functional Magnetic Resonance Imaging Study of Neural Dissociations between Brand and Person Judgments  

Microsoft Academic Search

Functional magnetic resonance imaging (fMRI) was used to investigate whether semantic judgments about products and persons are processed similarly. Our results suggest they are not: comparisons of neural correlates of product versus human descriptor judgments indicated greater activation in the medial prefrontal cortex regions for persons; for products, activation was greater in the left inferior prefrontal cortex, an area known

Carolyn Yoon; Fred Feinberg

2006-01-01

101

Temporal lobe abnormalities in semantic processing by criminal psychopaths as revealed by functional magnetic resonance imaging  

Microsoft Academic Search

We tested the hypothesis that psychopathy is associated with abnormalities in semantic processing of linguistic information. Functional magnetic resonance imaging (fMRI) was used to elucidate and characterize the neural architecture underlying lexico-semantic processes in criminal psychopathic individuals and in a group of matched control participants. Participants performed a lexical decision task in which blocks of linguistic stimuli alternated with a

Kent A. Kiehl; Andra M. Smith; Adrianna Mendrek; Bruce B. Forster; Robert D. Hare; Peter F. Liddle

2004-01-01

102

Recent developments of functional magnetic resonance imaging research for drug development in Alzheimer's disease  

Microsoft Academic Search

The objective of this review is to evaluate recent advances in functional magnetic resonance imaging (fMRI) research in Alzheimer's disease for the development of therapeutic agents. The basic building block underpinning cognition is a brain network. The measured brain activity serves as an integrator of the various components, from genes to structural integrity, that impact the function of networks underpinning

Harald Hampel; David Prvulovic; Stefan J. Teipel; Arun L. W. Bokde

103

AFNI: Software for Analysis and Visualization of Functional Magnetic Resonance Neuroimages  

Microsoft Academic Search

A package of computer programs for analysis and visualization of three-dimensional human brain functional magnetic resonance imaging (FMRI) results is described. The software can color overlay neural activation maps onto higher resolution anatomical scans. Slices in each cardinal plane can be viewed simultaneously. Manual placement of markers on anatomical landmarks allows transformation of anatomical and functional scans into stereotaxic (Talairach–Tournoux)

Robert W. Cox

1996-01-01

104

Functional Analysis of Human MT and Related Visual Cortical Areas Using Magnetic Resonance Imaging  

Microsoft Academic Search

Using noninvasive functional magnetic resonance imaging (fMRI) techniques, we analyzed the responses in human area MT with regard to visual motion, color, and luminance contrast sensitivity, and retinotopy. As in previous PET studies, we found that area MT responded selectively to moving (compared to stationary) stimuli. The location of human MT in the present fMRl results is consistent with that

Roger B. H. Tootell; John B. Reppas; Kenneth K. Kwong; Rafael Malach; Richard T. Born; Thomas J. Brady; Bruce R. Rosen; John W. Belliveaul

1995-01-01

105

The Hippocampal Formation Participates in Novel Picture Encoding: Evidence from Functional Magnetic Resonance Imaging  

Microsoft Academic Search

Considerable evidence exists to support the hypothesis that the hippocampus and related medial temporal lobe structures are crucial for the encoding and storage of information in long-term memory. Few human imaging studies, however, have successfully shown signal intensity changes in these areas during encoding or retrieval. Using functional magnetic resonance imaging (fMRI), we studied normal human subjects while they performed

Chantal E. Stern; Suzanne Corkin; R. Gilberto Gonzalez; Alexander R. Guimaraes; John R. Baker; Peggy J. Jennings; Cindy A. Carr; Robert M. Sugiura; Vasanth Vedantham; Bruce R. Rosen

1996-01-01

106

Evaluation of a magnetic resonance-compatible dentoalveolar tactile stimulus device  

Microsoft Academic Search

BACKGROUND: Few methods exist to study central nervous system processes following dentoalveolar tactile stimulation using functional magnetic resonance imaging (fMRI), likely due to inherent technical difficulties. Our primary goal was to develop and perform feasibility testing of a novel device capable of delivering valid and reliable dentoalveolar stimuli at dental chair-side and during MRI. Details of a device designed to

Estephan J Moana-Filho; Donald R Nixdorf; David A Bereiter; Mike T John; Noam Harel

2010-01-01

107

Physiological basis and image processing in functional magnetic resonance imaging: Neuronal and motor activity in brain  

PubMed Central

Functional magnetic resonance imaging (fMRI) is recently developing as imaging modality used for mapping hemodynamics of neuronal and motor event related tissue blood oxygen level dependence (BOLD) in terms of brain activation. Image processing is performed by segmentation and registration methods. Segmentation algorithms provide brain surface-based analysis, automated anatomical labeling of cortical fields in magnetic resonance data sets based on oxygen metabolic state. Registration algorithms provide geometric features using two or more imaging modalities to assure clinically useful neuronal and motor information of brain activation. This review article summarizes the physiological basis of fMRI signal, its origin, contrast enhancement, physical factors, anatomical labeling by segmentation, registration approaches with examples of visual and motor activity in brain. Latest developments are reviewed for clinical applications of fMRI along with other different neurophysiological and imaging modalities.

Sharma, Rakesh; Sharma, Avdhesh

2004-01-01

108

Metabolic brain imaging by magnetic resonance  

Microsoft Academic Search

Novel magnetic resonance methods have been developed to noninvasively measure biochemical compounds in the human brain as guided by magnetic resonance imaging. Together, these methods are referred to as magnetic resonance spectroscopy (MRS) and can be divided into three major categories: single voxel MRS, magnetic resonance spectroscopic imaging and dynamic MRS, which is a novel adaption of the first method.

Edward J Novotny Jr

2006-01-01

109

Lying about facial recognition: An fMRI study  

Microsoft Academic Search

Novel deception detection techniques have been in creation for centuries. Functional magnetic resonance imaging (fMRI) is a neuroscience technology that non-invasively measures brain activity associated with behavior and cognition. A number of investigators have explored the utilization and efficiency of fMRI in deception detection. In this study, 18 subjects were instructed during an fMRI “line-up” task to either conceal (lie)

S. Bhatt; J. Mbwana; A. Adeyemo; A. Sawyer; A. Hailu; J. VanMeter

2009-01-01

110

Lying in the scanner: covert countermeasures disrupt deception detection by functional magnetic resonance imaging.  

PubMed

Functional magnetic resonance imaging (fMRI) studies have documented differences between deceptive and honest responses. Capitalizing on this research, companies marketing fMRI-based lie detection services have been founded, generating methodological and ethical concerns in scientific and legal communities. Critically, no fMRI study has examined directly the effect of countermeasures, methods used by prevaricators to defeat deception detection procedures. An fMRI study was conducted to fill this research gap using a concealed information paradigm in which participants were trained to use countermeasures. Robust group fMRI differences between deceptive and honest responses were found without, but not with countermeasures. Furthermore, in single participants, deception detection accuracy was 100% without countermeasures, using activation in ventrolateral and medial prefrontal cortices, but fell to 33% with countermeasures. These findings show that fMRI-based deception detection measures can be vulnerable to countermeasures, calling for caution before applying these methods to real-world situations. PMID:21111834

Ganis, Giorgio; Rosenfeld, J Peter; Meixner, John; Kievit, Rogier A; Schendan, Haline E

2010-11-24

111

Magnetic Resonance Force Microscope Development  

SciTech Connect

Our objectives were to develop the Magnetic Resonance Force Microscope (MRFM) into an instrument capable of scientific studies of buried structures in technologically and scientifically important electronic materials such as magnetic multilayer materials. This work resulted in the successful demonstration of MRFM-detected ferromagnetic resonance (FMR) as a microscopic characterization tool for thin magnetic films. Strong FMR spectra obtained from microscopic Co thin films (500 and 1000 angstroms thick and 40 x 200 microns in lateral extent) allowed us to observe variations in sample inhomogeneity and magnetic anisotropy field. We demonstrated lateral imaging in microscopic FMR for the first time using a novel approach employing a spatially selective local field generated by a small magnetically polarized spherical crystallite of yttrium iron garnet. These successful applications of the MRFM in materials studies provided the basis for our successful proposal to DOE/BES to employ the MRF M in studies of buried interfaces in magnetic materials.

Hammel, P.C.; Zhang, Z.; Suh, B.J.; Roukes, M.L.; Midzor, M.; Wigen, P.E.; Childress, J.R.

1999-06-03

112

Lying about Facial Recognition: An fMRI Study  

ERIC Educational Resources Information Center

|Novel deception detection techniques have been in creation for centuries. Functional magnetic resonance imaging (fMRI) is a neuroscience technology that non-invasively measures brain activity associated with behavior and cognition. A number of investigators have explored the utilization and efficiency of fMRI in deception detection. In this…

Bhatt, S.; Mbwana, J.; Adeyemo, A.; Sawyer, A.; Hailu, A.; VanMeter, J.

2009-01-01

113

Study Design in fMRI: Basic Principles  

ERIC Educational Resources Information Center

|There is a wide range of functional magnetic resonance imaging (fMRI) study designs available for the neuroscientist who wants to investigate cognition. In this manuscript we review some aspects of fMRI study design, including cognitive comparison strategies (factorial, parametric designs), and stimulus presentation possibilities (block,…

Amaro, Edson, Jr.; Barker, Gareth J.

2006-01-01

114

Studying mind and brain with fMRI  

Microsoft Academic Search

The explosion in publications using functional magnetic resonance imaging (fMRI) warrants an examination of how the technique is being used to study processes of mind and brain. Here, we propose a classification of fMRI studies that reveals how this technique is being used in the service of understanding psychological and neural processes and the relationship between the two. In 1993,

Marc G. Berman; John Jonides; Derek Evan Nee

2006-01-01

115

Neuronal Clustering of Brain fMRI Images  

Microsoft Academic Search

Functional Magnetic Resonance Imaging (fMRI) allows the neuroscientists to observe the human brain in vivo. The current ap- proach consists in statistically validating their hypotheses. Data min- ing techniques provide an opportunity to help them in making up their hypotheses. This paper shows how a neuronal clustering technique can highlight active areas thanks to an appropriate distance between fMRI image

Nicolas Lachiche; Jean Hommet; Jerzy J. Korczak; Agnès Braud

2005-01-01

116

Acquiring and Inhibiting Prepotent Responses in Schizophrenia: Event-Related Brain Potentials and Functional Magnetic Resonance Imaging  

Microsoft Academic Search

Background: Schizophrenia is associated with deficits in using context to establish prepotent responses in com- plex paradigms and failures to inhibit prepotent re- sponses once established. Objective: To assess prepotent response establish- ment and inhibition in patients with schizophrenia us- ing event-related brain potential (ERP) and functional magnetic resonance imaging (fMRI) in a simple NoGo task. To combine fMRI and

Judith M. Ford; Max Gray; Susan L. Whitfield; U. Turken; Gary Glover; William O. Faustman; Daniel H. Mathalon; Lisa M. Shin; Scott P. Orr; Margaret A. Carson; Scott L. Rauch; Michael L. Macklin; Natasha B. Lasko; Patricia Marzol Peters; Linda J. Metzger; Darin D. Dougherty; Paul A. Cannistraro; Nathaniel M. Alpert; Alan J. Fischman; Roger K. Pitman

2004-01-01

117

The emotional counting stroop paradigm: a functional magnetic resonance imaging probe of the anterior cingulate affective division  

Microsoft Academic Search

Background: The emotional counting Stroop (ecStroop) functional magnetic resonance imaging (fMRI) activation paradigm was designed to recruit the anterior cingulate affective division (ACad).Methods: Nine normal, healthy male and female subjects (mean age 24.2 years) reported via button press the number of neutral and negative words that appeared on a screen while reaction time and fMRI data were acquired.Results: We observed

Paul J. Whalen; George Bush; Richard J. McNally; Sabine Wilhelm; Sean C. McInerney; Michael A. Jenike; Scott L. Rauch

1998-01-01

118

Neuroimaging Studies of Brain Activation for Language, with an Emphasis on Functional Magnetic Resonance Imaging: A Review  

Microsoft Academic Search

Neuroimaging studies have greatly enhanced the potential to understand brain-behavior relationships in complex behaviors such as language. The method of functional magnetic resonance imaging (fMRI) is one of the newest tools for neuroimaging, and it will in all likelihood contribute substantially to new knowledge about brain activation for language processing. This review summarizes basic information about fMRI, including principles of

Raymond D. Kent

1998-01-01

119

Primary Motor and Sensory Cortex Activation during Motor Performance and Motor Imagery: A Functional Magnetic Resonance Imaging Study  

Microsoft Academic Search

The intensity and spatial distribution of functional activation in the left precentral and postcentral gyri during actual motor performance (MP) and mental representation (motor imagery (MI)) of self-paced finger-to-thumb opposition movements of the dominant hand were investigated in fourteen right- handed volunteers by functional magnetic resonance imag- ing (fMRI) techniques. Significant increases in mean normal- ized fMRI signal intensities over

Carlo A. Porro; Maria Pia Francescato; Valentina Cettolo; Mathew E. Diamond; Patrizia Baraldi; Chiava Zuiani; Massimo Bazzocchi

1996-01-01

120

Interventional Cardiovascular Magnetic Resonance Imaging  

PubMed Central

Cardiovascular magnetic resonance (CMR) combines excellent soft-tissue contrast, multiplanar views, and dynamic imaging of cardiac function without ionizing radiation exposure. Interventional cardiovascular magnetic resonance (iCMR) leverages these features to enhance conventional interventional procedures or to enable novel ones. Although still awaiting clinical deployment, this young field has tremendous potential. We survey promising clinical applications for iCMR. Next, we discuss the technologies that allow CMR-guided interventions and, finally, what still needs to be done to bring them to the clinic.

Saikus, Christina E.; Lederman, Robert J.

2010-01-01

121

Ethics in fMRI Studies  

Microsoft Academic Search

Functional magnetic resonance imaging (fMRI) has surfaced as a powerful method to study brain function in humans. While the\\u000a involvement of neuroradiologists in fMRI studies in the clinical setting is obvious, in neuroscience research most of the\\u000a investigators are not specialists trained in reading brain images. Advances in neuroimaging are increasingly intersecting\\u000a with issues of ethical, legal, and social interest.

Daniela Seixas; Margarida Ayres Basto

2008-01-01

122

Chapter 1 Magnetic Resonance Contributions to Other Sciences  

NASA Astrophysics Data System (ADS)

In 1947, I.I. Rabi invented the molecular beam magnetic resonance method for the important, but limited purpose, of measuring nuclear magnetic moments and five of us working in his laboratory immediately began such experiments. The first experiments with LiCl gave the expected single resonance for each nucleus, but we were surprised to discover six resonances for the proton in H2, which we soon showed was due to the magnetic effects of the other proton and the rotating charged molecule: from these measurements we could also obtain new information on molecular structure. We had another shock when we studied D2 and found the resonance curves were spread more widely for D2 than H2 even though the magnetic interactions should have been much smaller. We found we could explain this by assuming that the deuteron had an electric quadrupole moment and J. Schwinger pointed out that this would require the existence of a previously unsuspected electric tensor force between the neutron and the proton. With this, the resonance method was giving new fundamental information about nuclear forces. In 1944, Rabi and I pointed out that it should be possible by the Dirac theory and our past resonance experiments to calculate exactly the hyperfine interaction between the electron and the proton in the hydrogen atom and we had two graduate students, Nafe and Nelson do the experiment and they found a disagreement which led J. Schwinger to develop the first successful relativistic quantum field theory and QED. In 1964, Purcell, Bloch and others detected magnetic resonance transitions by the effect of the transition on the oscillator, called NMR, making possible measurements on liquids, solids and gases and giving information on chemical shifts and thermal relaxation times T1 and T2. I developed a magnetic resonance method for setting a limit to the EDM of a neutron in a beam and with others for neutrons stored in a suitably coated bottle. Magnetic resonance measurements provide high stability atomic clocks. Both the second and the meter are now defined in terms of atomic clocks. Lauterbuhr, Mansfield, Damadian and others developed the important methods of using inhomogeneous magnetic fields to localize the magnetic resonance in a tissue sample producing beautiful and valuable magnetic resonance images, MRI's, and fMRI's.

Ramsey, Norman F.

123

Superconducting magnets for whole body magnetic resonance imaging  

Microsoft Academic Search

Superconducting magnets have achieved preeminence in the magnetic resonance imaging (MRI) industry. Further growth in this market will depend on reducing system costs, extending medical applications, and easing the present siting problem. New magnet designs from Oxford address these issues. Compact magnets are economical to build and operate. Two 4 Tesla whole body magnets for research in magnetic resonance spectroscopy

M. F. Murphy

1989-01-01

124

Susceptibility-Induced Loss of Signal: Comparing PET and fMRI on a Semantic Task  

Microsoft Academic Search

Functional magnetic resonance imaging (fMRI) has become a popular tool for investigations into the neural correlates of cognitive activity. One limitation of fMRI, however, is that it has difficulty imaging regions near tissue interfaces due to distortions from macroscopic susceptibility effects which become more severe at higher magnetic field strengths. This difficulty can be particularly problematic for language tasks that

Joseph T. Devlin; Richard P. Russell; Matt H. Davis; Cathy J. Price; James Wilson; Helen E. Moss; Paul M. Matthews; Lorraine K. Tyler

2000-01-01

125

Magnetic resonance apparatus  

DOEpatents

Means for producing a region of homogeneous magnetic field remote from the source of the field, wherein two equal field sources are arranged axially so their fields oppose, producing a region near the plane perpendicular to the axis midway between the sources where the radial component of the field goes through a maximum. Near the maximum, the field is homogeneous over prescribed regions.

Jackson, Jasper A. (Los Alamos, NM); Cooper, Richard K. (Los Alamos, NM)

1982-01-01

126

Magnetic resonance imaging in medicine  

Microsoft Academic Search

Over the past twenty years, magnetic resonance imaging (MRI) has become one of the most important imaging modalities available to clinical medicine. It offers great technical flexibility, and is free of the hazards associated with ionizing radiation. In addition to its role as a routine imaging technique with a growing range of clinical applications, the pace of development in MRI

Stephen F. Keevil

2001-01-01

127

The neural basis of the blood-oxygen-level-dependent functional magnetic resonance imaging signal.  

PubMed Central

Magnetic resonance imaging (MRI) has rapidly become an important tool in clinical medicine and biological research. Its functional variant (functional magnetic resonance imaging; fMRI) is currently the most widely used method for brain mapping and studying the neural basis of human cognition. While the method is widespread, there is insufficient knowledge of the physiological basis of the fMRI signal to interpret the data confidently with respect to neural activity. This paper reviews the basic principles of MRI and fMRI, and subsequently discusses in some detail the relationship between the blood-oxygen-level-dependent (BOLD) fMRI signal and the neural activity elicited during sensory stimulation. To examine this relationship, we conducted the first simultaneous intracortical recordings of neural signals and BOLD responses. Depending on the temporal characteristics of the stimulus, a moderate to strong correlation was found between the neural activity measured with microelectrodes and the BOLD signal averaged over a small area around the microelectrode tips. However, the BOLD signal had significantly higher variability than the neural activity, indicating that human fMRI combined with traditional statistical methods underestimates the reliability of the neuronal activity. To understand the relative contribution of several types of neuronal signals to the haemodynamic response, we compared local field potentials (LFPs), single- and multi-unit activity (MUA) with high spatio-temporal fMRI responses recorded simultaneously in monkey visual cortex. At recording sites characterized by transient responses, only the LFP signal was significantly correlated with the haemodynamic response. Furthermore, the LFPs had the largest magnitude signal and linear systems analysis showed that the LFPs were better than the MUAs at predicting the fMRI responses. These findings, together with an analysis of the neural signals, indicate that the BOLD signal primarily measures the input and processing of neuronal information within a region and not the output signal transmitted to other brain regions.

Logothetis, Nikos K

2002-01-01

128

Adaptive filtering and random variables coefficient for analyzing functional magnetic resonance imaging data.  

PubMed

Functional magnetic resonance imaging (fMRI) is used to study brain functional connectivity (FC) after filtering the physiological noise (PN). Herein, we employ: adaptive filtering for removing nonstationary PN; random variables (RV) coefficient for FC analysis. Comparisons with standard techniques were performed by quantifying PN filtering and FC in neural vs. non-neural regions. As a result, adaptive filtering plus RV coefficient showed a greater suppression of PN and higher connectivity in neural regions, representing a novel effective approach to analyze fMRI data. PMID:23627658

Piaggi, Paolo; Menicucci, Danilo; Gentili, Claudio; Handjaras, Giacomo; Gemignani, Angelo; Landi, Alberto

2013-03-26

129

Magnetic resonance of a single molecular spin  

Microsoft Academic Search

Magnetic-resonance spectroscopy on single molecules represents the ultimate limit in sensitivity of electron spin resonance: the detection of a single molecular spin. This is achieved by combining single molecule spectroscopy and optically detected magnetic resonance. Experimental results on pentacene in p-terphenyl both in zero-field and in the presence of a weak magnetic field demonstrate that magnetic-resonance spectroscopy on single molecules

Jürgen Köhler

1999-01-01

130

Magnetic Resonance Spectroscopy and Magnetic Resonance Imaging Findings in Krabbe's Disease  

Microsoft Academic Search

Two twins with late infantile globoid cell leukodystrophy or Krabbe's disease were studied with conventional magnetic resonance imaging (MRI) and proton magnetic resonance spectroscopy. Brain MRI demonstrated brain atrophy with extensive bilateral symmetric abnormal T2 signal in the posterior periventricular white matter, parietal lobes, corona radiata, centrum semiovale, and splenium of the corpus callosum. Magnetic resonance imaging-guided proton magnetic resonance

Maria K. Zarifi; A. Aria Tzika; Loukas G. Astrakas; Tina Young Poussaint; Douglas C. Anthony; Basil T. Darras

2001-01-01

131

Phase stability in fMRI time series: effect of noise regression, off-resonance correction and spatial filtering techniques.  

PubMed

Although the majority of fMRI studies exploit magnitude changes only, there is an increasing interest regarding the potential additive information conveyed by the phase signal. This integrated part of the complex number furnished by the MR scanners can also be used for exploring direct detection of neuronal activity and for thermography. Few studies have explicitly addressed the issue of the available signal stability in the context of phase time-series, and therefore we explored the spatial pattern of frequency specific phase fluctuations, and evaluated the effect of physiological noise components (heart beat and respiration) on the phase signal. Three categories of retrospective noise reduction techniques were explored and the temporal signal stability was evaluated in terms of a physiologic noise model, for seven fMRI measurement protocols in eight healthy subjects at 3T, for segmented CSF, gray and white matter voxels. We confirmed that for most processing methods, an efficient use of the phase information is hampered by the fact that noise from physiological and instrumental sources contributes significantly more to the phase than to the magnitude instability. Noise regression based on the phase evolution of the central k-space point, RETROICOR, or an orthonormalized combination of these were able to reduce their impact, but without bringing phase stability down to levels expected from the magnitude signal. Similar results were obtained after targeted removal of scan-to-scan variations in the bulk magnetic field by the dynamic off-resonance in k-space (DORK) method and by the temporal off-resonance alignment of single-echo time series technique (TOAST). We found that spatial high-pass filtering was necessary, and in vivo a Gaussian filter width of 20mm was sufficient to suppress physiological noise and bring the phase fluctuations to magnitude levels. Stronger filters brought the fluctuations down to levels dictated by thermal noise contributions, and for 62.5mm(3) voxels the phase stability was as low as 5 mrad (0.27°). In conditions of low SNR(o) and high temporal sampling rate (short TR); we achieved an upper bound for the phase instabilities at 0.0017 ppm, which is close to the dHb contribution to the GM/WM phase contrast. PMID:22079450

Hagberg, Gisela E; Bianciardi, Marta; Brainovich, Valentina; Cassara, Antonino Mario; Maraviglia, Bruno

2011-11-04

132

Magnetic Resonance Reporter Gene Imaging  

PubMed Central

Molecular imaging has undergone an explosive advancement in recent years, due to the tremendous research efforts made to understand and visualize biological processes. Molecular imaging by definition assesses cellular and molecular processes in living subjects, with the targets of following metabolic, genomic, and proteomic events. Furthermore, reporter gene imaging plays a central role in this field. Many different approaches have been used to visualize genetic events in living subjects, such as, optical, radionuclide, and magnetic resonance imaging. Compared with the other techniques, magnetic resonance (MR)-based reporter gene imaging has not occupied center stage, despite its superior three-dimensional depictions of anatomical details. In this article, the authors review the principles and applications of various types of MR reporter gene imaging technologies and discuss their advantages and disadvantages.

Lee, Sheen-Woo; Lee, Sang-Hoon; Biswal, Sandip

2012-01-01

133

Spatiotemporal spiral magnetic resonance imaging  

NASA Astrophysics Data System (ADS)

This paper addresses the problem of Magnetic Resonance (MR) imaging of moving targets using spiral scan echo planar data collection. A system model is developed to interpret the readouts of repeated spiral excitations via two separate time variables, the slow-time and fast-time. This mathematical model is used to construct an inversion for forming the time progression of the target image. A method for increasing the repetition rate of the spiral data collection is presented. Results are provided.

Soumekh, Mehrdad

1999-05-01

134

A case of persistent visual hallucinations of faces following LSD abuse: A functional Magnetic Resonance Imaging study  

Microsoft Academic Search

In this study, we report the case of a patient experiencing hallucinations of faces that could be reliably precipitated by looking at trees. Using functional Magnetic Resonance Imaging (fMRI), we found that face hallucinations were associated with increased and decreased neural activity in a number of cortical regions. Within the same fusiform face area, however, we found significant decreased and

Giuseppe Iaria; Christopher J. Fox; Michael Scheel; Robert M. Stowe; Jason J. S. Barton

2010-01-01

135

Relation of Reward From Food Intake and Anticipated Food Intake to Obesity: A Functional Magnetic Resonance Imaging Study  

Microsoft Academic Search

The authors tested the hypothesis that obese individuals experience greater reward from food consumption (consummatory food reward) and anticipated consumption (anticipatory food reward) than lean individuals using functional magnetic resonance imaging (fMRI) with 33 adolescent girls (mean age = 15.7, SD = 0.9). Obese relative to lean adolescent girls showed greater activation bilaterally in the gustatory cortex (anterior and mid

Eric Stice; Sonja Spoor; Cara Bohon; Marga G. Veldhuizen; Dana M. Small

2008-01-01

136

Functional Magnetic Resonance Imaging Measures of Blood Flow Patterns in the Human Auditory Cortex in Response to Sound.  

ERIC Educational Resources Information Center

|This study examined the feasibility of using functional magnetic resonance imaging (fMRI) in auditory research by testing the reliability of scanning parameters using high resolution and high signal-to-noise ratios. Findings indicated reproducibility within and across listeners for consonant-vowel speech stimuli and reproducible results within…

Huckins, Sean C.; Turner, Christopher W.; Doherty, Karen A.; Fonte, Michael M.; Szeverenyi, Nikolaus M.

1998-01-01

137

Laterality in Metaphor Processing: Lack of Evidence from Functional Magnetic Resonance Imaging for the Right Hemisphere Theory  

ERIC Educational Resources Information Center

We investigated processing of metaphoric sentences using event-related functional magnetic resonance imaging (fMRI). Seventeen healthy subjects (6 female, 11 male) read 60 novel short German sentence pairs with either metaphoric or literal meaning and performed two different tasks: judging the metaphoric content and judging whether the sentence…

Rapp, Alexander M.; Leube, Dirk T.; Erb, Michael; Grodd, Wolfgang; Kircher, Tilo T. J.

2007-01-01

138

Paradoxical correlation between signal in functional magnetic resonance imaging and deoxygenated haemoglobin content in capillaries: a new theoretical explanation  

Microsoft Academic Search

Signal increases in functional magnetic resonance imaging (fMRI) are believed to be a result of decreased paramagnetic deoxygenated haemoglobin (deoxyHb) content in the neural activation area. However, discrepancies in this canonical blood oxygenation level dependent (BOLD) theory have been pointed out in studies using optical techniques, which directly measure haemoglobin changes. To explain the discrepancies, we developed a new theory

Toru Yamamoto; Toshinori Kato

2002-01-01

139

Bilingual and Monolingual Brains Compared: A Functional Magnetic Resonance Imaging Investigation of Syntactic Processing and a Possible \\  

Microsoft Academic Search

Does the brain of a bilingual process language differently from that of a monolingual? We compared how bilinguals and monolinguals recruit classic language brain areas in response to a language task and asked whether there is a ''neural signature'' of bilingualism. Highly proficient and early-exposed adult Spanish- English bilinguals and English monolinguals participated. During functional magnetic resonance imaging (fMRI), partic-

Ioulia Kovelman; Stephanie A. Baker; Laura-ann Petitto

2008-01-01

140

SQUID-Detected Magnetic Resonance Imaging in Microtesla Magnetic Fields  

Microsoft Academic Search

We describe studies of nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging (MRI) of liquid samples at room temperature in microtesla magnetic fields. The nuclear spins are prepolarized in a strong transient field. The magnetic signals generated by the precessing spins, which range in frequency from tens of Hz to several kHz, are detected by a low-transition temperature dc

R. McDermott; N. Kelso; S. K. Lee; M. MöBetale; M. Mück; W. Myers; B. ten Haken; H. C. Seton; A. H. Trabesinger; A. Pines; J. Clarke

2004-01-01

141

Bistable electron magnetic resonance in solids  

Microsoft Academic Search

This paper describes the phenomenon of Bistable Electron Magnetic Resonance, which manifests itself by a resonance line with a distorted shark fin-like shape. This effect requires only a fluctuating hyperfine interaction between electron spins and nuclear spins. It is demonstrated for shallow donors in semiconductors and conduction electrons in light metals. Bistability is an intrinsic property of electron magnetic resonance

Didier Gourier; Laurent Binet; Olivier Guillot-Noël

2004-01-01

142

Trial-by-trial coupling of concurrent electroencephalogram and functional magnetic resonance imaging identifies the dynamics of performance monitoring.  

PubMed

Goal-directed behavior requires the continuous monitoring and dynamic adjustment of ongoing actions. Here, we report a direct coupling between the event-related electroencephalogram (EEG), functional magnetic resonance imaging (fMRI), and behavioral measures of performance monitoring in humans. By applying independent component analysis to EEG signals recorded simultaneously with fMRI, we found the single-trial error-related negativity of the EEG to be systematically related to behavior in the subsequent trial, thereby reflecting immediate behavioral adjustments of a cognitive performance monitoring system. Moreover, this trial-by-trial EEG measure of performance monitoring predicted the fMRI activity in the rostral cingulate zone, a brain region thought to play a key role in processing of response errors. We conclude that investigations of the dynamic coupling between EEG and fMRI provide a powerful approach for the study of higher order brain functions. PMID:16354931

Debener, Stefan; Ullsperger, Markus; Siegel, Markus; Fiehler, Katja; von Cramon, D Yves; Engel, Andreas K

2005-12-14

143

Growth Hormone Deficiency and Memory Functioning in Adults Visualized by Functional Magnetic Resonance Imaging  

Microsoft Academic Search

Cognitive functioning, especially memory performance, is known to be impaired in patients with childhood-onset growth hormone deficiency (CO-GHD), and growth hormone substitution has been found to counteract this memory impairment. Neuropsychological and functional magnetic resonance imagining (fMRI) data acquired during a working memory task in 13 childhood-onset GH-deficient patients were compared with 13 age, sex and education level matched healthy

Lucia I. Arwert; Dick J. Veltman; Jan Berend Deijen; P. Sytze van Dam; Henriette A. Delemarre-van deWaal; Madeleine L. Drent

2005-01-01

144

Functional magnetic resonance imaging evidence of augmented pain processing in fibromyalgia  

Microsoft Academic Search

Objective. To use functional magnetic resonance imaging (fMRI) to evaluate the pattern of cerebral activation during the application of painful pressure and determine whether this pattern is augmented in patients with fibromyalgia (FM) compared with con- trols. Methods. Pressure was applied to the left thumb- nail beds of 16 right-handed patients with FM and 16 right-handed matched controls. Each FM

Richard H. Gracely; Frank Petzke; Julie M. Wolf; Daniel J. Clauw

2002-01-01

145

Nonlinear denoising of functional magnetic resonance imaging time series with wavelets  

Microsoft Academic Search

In functional magnetic resonance imaging (fMRI) the blood oxygenation level dependent (BOLD) effect is used to identify and delineate neuronal activity. The sensitivity of a fMRI-based detection of neuronal activation, however, strongly depends on the relative levels of signal and noise in the time series data, and a large number of different artifact and noise sources interfere with the weak

Sven Stausberg; Klaus Lehnertz

2009-01-01

146

Striatal recruitment during an implicit sequence learning task as measured by functional magnetic resonance imaging  

Microsoft Academic Search

Prior research has repeatedly implicated the striatum in implicit sequence learning; however, imaging findings have been inconclusive with respect to the sub-territories and laterality involved. Using functional magnetic resonance imaging (fMRI), we studied brain activation profiles associated with performance of the serial reaction time task (SRT) in 10 normal right-handed males. Behavioral results indicate that significant implicit learning occurred, uncontaminated

Scott L. Rauch; Paul J. Whalen; Cary R. Savage; Tim Curran; Adair Kendrick; Halle D. Brown; George Bush; Hans C. Breiter; Bruce R. Rosen

1997-01-01

147

Magnetic resonance methods and applications in pharmaceutical research.  

PubMed

This review presents an overview of some recent magnetic resonance (MR) techniques for pharmaceutical research. MR is noninvasive, and does not expose subjects to ionizing radiation. Some methods that have been used in pharmaceutical research MR include magnetic resonance spectroscopy (MRS) and magnetic resonance imaging (MRI) methods, among them, diffusion-weighted MRI, perfusion-weighted MRI, functional MRI, molecular imaging and contrast-enhance MRI. Some applications of MR in pharmaceutical research include MR in metabonomics, in vivo MRS, studies in cerebral ischemia and infarction, degenerative joint diseases, oncology, cardiovascular disorders, respiratory diseases and skin diseases. Some of these techniques, such as cardiac and joint imaging, or brain fMRI are standard, and are providing relevant data routinely. Skin MR and hyperpolarized gas lung MRI are still experimental. In conclusion, considering the importance of finding and characterizing biomarkers for improved drug evaluation, it can be expected that the use of MR techniques in pharmaceutical research is going to increase in the near future. PMID:18228597

Rodríguez, I; Pérez-Rial, S; González-Jimenez, J; Pérez-Sánchez, Jm; Herranz, F; Beckmann, N; Ruíz-Cabello, J

2008-09-01

148

Clinical assessment of ischemia and malignancy with magnetic resonance spectroscopy  

Microsoft Academic Search

Summary form only given. Using recent developments in construction of high field magnets, magnetic resonance spectroscopy has been integrated with magnetic resonance imaging for clinical use. Magnetic resonance (MR) spectra can be obtained from an image-defined volume of interest using a variety of magnetic resonance localization techniques. Recently, magnetic resonance spectroscopic imaging techniques have been developed which fully combine MR

M. W. Weiner

1988-01-01

149

Event-related fMRI in Cognition  

PubMed Central

A primary advantage of functional magnetic resonance imaging (fMRI) over other techniques in neuroscience is its flexibility. Researchers have used fMRI to study a remarkable diversity of topics, from basic processes of perception and memory, to the complex mechanisms of economic decision making and moral cognition. The chief contributor to this experimental flexibility – indeed, to the growth of fMRI itself – has been the development of event-related experimental designs and associated analyses. The core idea of an event-related design, as first articulated in the late 1990s, is the separation of cognitive processes into discrete points in time (i.e., “events”) allowing differentiation of their associated fMRI signals. By modeling brain function as a series of transient changes, rather than as an ongoing state, event-related fMRI allowed researchers to create much more complex paradigms and more dynamic analysis methods. Yet, this flexibility came with a cost. As the complexity of experimental designs increased, fMRI analyses became increasingly abstracted from the original data, which in turn has had consequences both positive (e.g., greater use of model-based fMRI) and negative (e.g., fewer articles plot the timing of activation). And, as event-related methods have become ubiquitous, they no longer represent a distinct category of fMRI research. In a real sense, event-related fMRI has now become, simply, fMRI.

Huettel, Scott A.

2011-01-01

150

Event-related fMRI in cognition.  

PubMed

A primary advantage of functional magnetic resonance imaging (fMRI) over other techniques in neuroscience is its flexibility. Researchers have used fMRI to study a remarkable diversity of topics, from basic processes of perception and memory, to the complex mechanisms of economic decision making and moral cognition. The chief contributor to this experimental flexibility-indeed, to the growth of fMRI itself-has been the development of event-related experimental designs and associated analyses. The core idea of an event-related design, as first articulated in the late 1990s, is the separation of cognitive processes into discrete points in time (i.e., "events") allowing differentiation of their associated fMRI signals. By modeling brain function as a series of transient changes, rather than as an ongoing state, event-related fMRI allowed researchers to create much more complex paradigms and more dynamic analysis methods. Yet, this flexibility came with a cost. As the complexity of experimental designs increased, fMRI analyses became increasingly abstracted from the original data, which in turn has had consequences both positive (e.g., greater use of model-based fMRI) and negative (e.g., fewer articles plot the timing of activation). And, as event-related methods have become ubiquitous, they no longer represent a distinct category of fMRI research. In a real sense, event-related fMRI has now become, simply, fMRI. PMID:21963919

Huettel, Scott A

2011-09-22

151

Localized ferromagnetic resonance using Magnetic Resonance Force Microscopy  

Microsoft Academic Search

Magnetic Resonance Force Microscopy (MRFM) is a novel approach to scanned probe imaging, combining the advantages of Magnetic Resonance Imaging (MRI) with Scanning Probe Microscopy (SPM) [1]. It has extremely high sensitivity that has demonstrated detection of individual electron spins [2] and small numbers of nuclear spins [3]. Here we describe our MRFM experiments on Ferromagnetic thin film structures. Unlike

Jongjoo Kim

2008-01-01

152

Neurophysiological investigation of the basis of the fMRI signal  

Microsoft Academic Search

Functional magnetic resonance imaging (fMRI) is widely used to study the operational organization of the human brain, but the exact relationship between the measured fMRI signal and the underlying neural activity is unclear. Here we present simultaneous intracortical recordings of neural signals and fMRI responses. We compared local field potentials (LFPs), single- and multi-unit spiking activity with highly spatio-temporally resolved

Nikos K. Logothetis; Jon Pauls; Mark Augath; Torsten Trinath; Axel Oeltermann

2001-01-01

153

Analysis of activity in fMRI data for multitask experimental paradigm using affinity propagation clustering  

Microsoft Academic Search

Clustering analysis is a promising data-driven method for the analysis of functional magnetic resonance imaging (fMRI) data. We use affinity propagation clustering (APC), a new clustering algorithm especially for large data sets, to detect brain functional activation from fMRI in multitask experimental paradigm. The real fMRI study reveals that brain functional activation can be effectively detected and that different response

Jiang Zhang; Huafu Chen

2010-01-01

154

Towards a virtual laboratory for fMRI data management and analysis  

Microsoft Academic Search

Functional Magnetic Resonance Imaging (fMRI) is a popular tool used in neuroscience research to study brain activation due to mo- tor or cognitive stimulation. In fMRI studies, large amounts of data are acquired, processed, compared, annotated, shared by many users and archived for future reference. As such, fMRI studies have characteristics of applications that can benefit from grid computation approaches,

Silvia D. Olabarriaga; Aart J. Nederveen; Jeroen G. Snel; Robert G. Belleman

2006-01-01

155

Magnetic Resonance Spectroscopy in Biological Systems.  

National Technical Information Service (NTIS)

These notes give a general view of the various methods of magnetic resonance spectroscopy and of their possible applications to biological and medical problems. After analyzing the fundamental NMR and EPR techniques, double resonance (ENDOR), pulsed NMR a...

E. Tiezzi

1971-01-01

156

Magnetic Resonance Force Microscopy with Magnetic Tiped Cantilevers  

NASA Astrophysics Data System (ADS)

Magnetic resonance force microscopy has been performed, until recently, by attaching the sample under study to a fragile microcantilever. Increasing the resolution, force-sensitivity and practicality of the technique, demands both reducing the size of the magnetic particle and measuring magnetic resonance as an excitation of magnetic-tip cantilevers. To lift the sample-on-cantilever restriction we have succesfully attached and controllably magnetized a micron-size Alnico particle to the end of a commercial Si cantilever. We will describe the techniques and protocols used to magnetize and characterize the magnetic particles as well as the mechanical detection of electron spin resonance with these probes.

Marohn, John A.; Fainchtein, Raul; Smith, Doran D.

1998-03-01

157

Magnetic resonance imaging of acquired cardiac disease.  

PubMed Central

Over the last 15 years, advances in magnetic resonance imaging techniques have increased the accuracy and applicability of cardiovascular magnetic resonance imaging. These advances have improved the utility of magnetic resonance imaging in evaluating cardiac morphology, blood flow, and myocardial contractility, all significant diagnostic features in the evaluation of the patient with acquired heart disease. Utilization of cardiovascular magnetic resonance imaging has been limited, primarily due to clinical reliance upon nuclear scintigraphy and echocardiography. Recent developments in fast and ultrafast imaging should continue to enhance the significance of magnetic resonance imaging in this field. Widespread use of magnetic resonance imaging in the evaluation of the cardiovascular system will ultimately depend upon its maturation into a comprehensive, noninvasive imaging technique for the varying manifestations of acquired heart disease, including cardiomyopathy, ischemic heart disease, and acquired valvular disease. Images

Carrol, C L; Higgins, C B; Caputo, G R

1996-01-01

158

Pharmacological Stress Cardiovascular Magnetic Resonance  

PubMed Central

Over the past decade, cardiovascular magnetic resonance (CMR) has evolved into a cardiac stress testing modality that can be used to diagnose myocardial ischemia using intravenous dobutamine or vasodilator perfusion agents such as adenosine or dipyridamole. Because CMR produces high-resolution tomographic images of the human heart in multiple imaging planes, it has become a highly attractive noninvasive testing modality for those suspected of having myocardial ischemia. The purpose of this article is to review the clinical, diagnostic, and prognostic utility of stress CMR testing for patients with (or suspected of having) coronary artery disease.

Chotenimitkhun, Runyawan; Hundley, W. Gregory

2013-01-01

159

[Magnetic resonance imaging elbow anatomy].  

PubMed

Knowledge of the anatomy of the elbow joint has become intricate due to the advent of magnetic resonance imaging (MRI) techniques, as they are superior to represent the different soft tissues. This advantage allows evaluating in detail the increasingly frequent pathologic processes that occur in high performance athletes. The ideal MRI technique includes having the patient in a comfortable position, using an appropriate surface antenna and the right sequences in the appropriate planes depending on the entity. Being familiar with the normal elbow anatomy is crucial to properly identify the pathology and avoid potential diagnostic errors. PMID:22509650

Rodríguez-Ramírez, C L; Aguila-Mendoza, A

160

Quantitative fMRI and oxidative neuroenergetics  

PubMed Central

The discovery of functional magnetic resonance imaging (fMRI) has greatly impacted neuroscience. The blood oxygenation level-dependent (BOLD) signal, using deoxyhemoglobin as an endogenous paramagnetic contrast agent, exposes regions of interest in task-based and resting-state paradigms. However the BOLD contrast is at best a partial measure of neuronal activity, because the functional maps obtained by differencing or correlations ignore the total neuronal activity in the baseline state. Here we describe how studies of brain energy metabolism at Yale, especially with 13C magnetic resonance spectroscopy and related techniques, contributed to development of quantitative functional brain imaging with fMRI by providing a reliable measurement of baseline energy. This narrative takes us on a journey, from molecules to mind, with illuminating insights about neuronal-glial activities in relation to energy demand of synaptic activity. These results, along with key contributions from laboratories worldwide, comprise the energetic basis for quantitative interpretation of fMRI data.

Hyder, Fahmeed; Rothman, Douglas L.

2012-01-01

161

Superconducting magnets for whole body magnetic resonance imaging  

SciTech Connect

Superconducting magnets have achieved preeminence in the magnetic resonance imaging (MRI) industry. Further growth in this market will depend on reducing system costs, extending medical applications, and easing the present siting problem. New magnet designs from Oxford address these issues. Compact magnets are economical to build and operate. Two 4 Tesla whole body magnets for research in magnetic resonance spectroscopy (MRS) are now in operation. Active-Shield magnets, by drastically reducing the magnetic fringe fields, will allow MRI systems with superconducting magnets to be located in previously inaccessible sites.

Murphy, M.F.

1989-03-01

162

Early functional brain development in autism and the promise of sleep fMRI  

Microsoft Academic Search

Functional magnetic resonance imaging (fMRI) is a powerful tool for examining brain function but has yet to be systematically applied to the study of brain development in autism. Recently, however, scientists have begun to apply fMRI during natural sleep as a mechanism to study function in the developing brain. When considering the study of autism, this method opens considerable doors

Karen Pierce

2011-01-01

163

Analysis of fMRI Data With Drift: Modified General Linear Model and Bayesian Estimator  

Microsoft Academic Search

The slowly varying drift poses a major problem in the analysis of functional magnetic resonance imaging (fMRI) data. In this paper, based on the observation that noise in fMRI is long memory fractional noise and the slowly varying drift resides in a subspace spanned only by large scale wavelets, we examine a modified general linear model (GLM) in wavelet domain

Huaien Luo; Sadasivan Puthusserypady

2008-01-01

164

Contextual Detection of FMRI Activations and Multimodal Aspects of Brain Imaging.  

National Technical Information Service (NTIS)

Functional magnetic resonance imaging (fMRI) is a non-invasive method which can be used to indirectly localize neuronal activations in the human brain. Functional MRI is based on changes in the blood oxygenation level near the activated tissue. In an fMRI...

E. Salli

2002-01-01

165

An MRF spatial fuzzy clustering method for fMRI SPMs  

Microsoft Academic Search

The paper presents a method for spatial fuzzy clustering (SFC) via Markov Random Fields (MRF) for the detection of brain activation regions in Functional Magnetic Resonance Imaging (fMRI) statistical parametric maps (SPMs) to improve the accuracy of the detection of such regions. The fMRI SPM is assumed to be an MRF and we define a fuzzy neighborhood energy function to

Lili He; Ian R. Greenshields

2008-01-01

166

GABA concentrations in the human anterior cingulate cortex predict negative BOLD responses in fMRI  

Microsoft Academic Search

The human anterior cingulate cortex (ACC) is part of the default-mode network that shows predominant negative blood oxygen level–dependent (BOLD) responses in functional magnetic resonance imaging (fMRI). We combined fMRI during emotional processing and resting-state magnetic resonance spectroscopy measurements and observed that the concentration of GABA in the ACC specifically correlated with the amount of negative BOLD responses in the

Martin Walter; Rolf F Schulte; Johannes Beck; Ulrike Dydak; Anke Henning; Heinz Boeker; Simone Grimm; Peter Boesiger; Georg Northoff

2007-01-01

167

MAGNETIC RESONANCE ELASTOGRAPHY: A REVIEW  

PubMed Central

Magnetic Resonance Elastography (MRE) is a rapidly developing technology for quantitatively assessing the mechanical properties of tissue. The technology can be considered to be an imaging-based counterpart to palpation, commonly used by physicians to diagnose and characterize diseases. The success of palpation as a diagnostic method is based on the fact that the mechanical properties of tissues are often dramatically affected by the presence of disease processes such as cancer, inflammation, and fibrosis. MRE obtains information about the stiffness of tissue by assessing the propagation of mechanical waves through the tissue with a special magnetic resonance imaging (MRI) technique. The technique essentially involves three steps: generating shear waves in the tissue,acquiring MR images depicting the propagation of the induced shear waves andprocessing the images of the shear waves to generate quantitative maps of tissue stiffness, called elastograms. MRE is already being used clinically for the assessment of patients with chronic liver diseases and is emerging as a safe, reliable and noninvasive alternative to liver biopsy for staging hepatic fibrosis. MRE is also being investigated for application to pathologies of other organs including the brain, breast, blood vessels, heart, kidneys, lungs and skeletal muscle. The purpose of this review article is to introduce this technology to clinical anatomists and to summarize some of the current clinical applications that are being pursued.

Mariappan, Yogesh K; Glaser, Kevin J; Ehman, Richard L

2011-01-01

168

Magnetic Resonance Imaging System Based on Earth's Magnetic Field  

Microsoft Academic Search

This article describes both the setup and the use of a system for magnetic resonance imaging (MRI) in the Earth's magnetic field. Phase instability caused by temporal fluctuations of Earth's field can be successfully improved by using a reference signal from a separate Earth's field nuclear magnetic resonance (NMR) spectrometer\\/magnetometer. In imaging, it is important to correctly determine the phase

Ales Mohoric; Gorazd Planinsic; Miha Kos; Andrej Duh; Janez Stepisnik

2004-01-01

169

A mechanical analog of nuclear magnetic resonance  

NSDL National Science Digital Library

A mechanical analog apparatus for teaching Nuclear Magnetic Resonance is assembled of PVC, an air-bearing, a magnetic sphere, two sheet magnets, and a pair of Helmholtz coils. The magnetic sphere spins in the air-bearing due to turbine torque and acts as an ensemble of protons in the NMR system. The Helmholtz coils allow us to supply an AC magnetic field to perturb the sphere and search for resonance. The sheet magnets are on a slide. By moving them closer or further from the air bearing, we adjust the magnetic field at the sphere. The field at the air bearing is relatively uniform.

Masters, Mark F.

2013-02-13

170

Advances in mechanical detection of magnetic resonance  

PubMed Central

The invention and initial demonstration of magnetic resonance force microscopy (MRFM) in the early 1990s launched a renaissance of mechanical approaches to detecting magnetic resonance. This article reviews progress made in MRFM in the last decade, including the demonstration of scanned probe detection of magnetic resonance (electron spin resonance, ferromagnetic resonance, and nuclear magnetic resonance) and the mechanical detection of electron spin resonance from a single spin. Force and force-gradient approaches to mechanical detection are reviewed and recent related work using attonewton sensitivity cantilevers to probe minute fluctuating electric fields near surfaces is discussed. Given recent progress, pushing MRFM to single proton sensitivity remains an exciting possibility. We will survey some practical and fundamental issues that must be resolved to meet this challenge.

Kuehn, Seppe; Hickman, Steven A.; Marohn, John A.

2008-01-01

171

Perspective of functional magnetic resonance imaging in middle ear research.  

PubMed

Functional magnetic resonance imaging (MRI) studies have frequently been applied to study sensory system such as vision, language, and cognition, but have proceeded at a considerably slower speed in investigating middle ear and central auditory processing. This is due to several factors, including the intrinsic anatomy of the middle ear system and inherent acoustic noise during acquisition of MRI data. However, accumulating evidences have demonstrated that clarification of some fundamental neural underpinnings of audition associated with middle ear mechanics can be achieved using functional MRI methods. This mini review attempted to take a narrow snapshot of the currently available functional MRI procedures and gave examples of what may be learned about hearing from their application. It is hoped that with these technical advancements, many new high impact applications in audition would follow. In particular, because the fMRI can be used in humans and in animals, fMRI may represent a unique tool that should promote translational research by enabling parallel analyses of physiological and pathological processes in the human and animal auditory system. This article is part of a special issue entitled "MEMRO 2012". PMID:23291496

Chang, Yongmin; Lee, Sang-Heun

2013-01-02

172

Magnetic resonance arthrography of the upper extremity.  

PubMed

Although magnetic resonance arthrography is not indicated for every clinical scenario, capsular distention can significantly improve visualization of intra-articular pathologic conditions. With attention to technique, intraarticular injection can be completed successfully with little patient discomfort. This article provides details of the technique for injection of the shoulder, the elbow, and the wrist for optimization of magnetic resonance imaging. PMID:23472588

Lomasney, Laurie M; Choi, Haemi; Jayanthi, Neeru

2012-12-20

173

Existence of resonances in magnetic scattering  

NASA Astrophysics Data System (ADS)

The Schrödinger operator with a compactly supported magnetic field is shown to produce infinitely many resonances, in any odd dimension[greater-or-equal, slanted]3. The proof is based on the Poisson formula for resonances and properties of the magnetic heat invariants.

Hitrik, Michael

2002-11-01

174

Advances in Magnetic Resonance Electrical Impedance Mammography  

Microsoft Academic Search

Magnetic Resonance Electrical Impedance Mammography (MREIM) is a new imaging technique under development by Wollin Ventures, Inc. in conjunction with the H. Lee Moffitt Cancer Center & Research Institute. MREIM addresses the problem of low specificity of magnetic resonance mammography and high false-positive rates, which lead to unnecessary biopsies. Because cancerous tissue has a higher electrical conductivity than benign tissue,

Nataliya Kovalchuk

2008-01-01

175

Chemical Principles Revisited. Proton Magnetic Resonance Spectroscopy.  

ERIC Educational Resources Information Center

|Discusses how to interpret nuclear magnetic resonance (NMR) spectra and how to use them to determine molecular structures. This discussion is limited to spectra that are a result of observation of only the protons in a molecule. This type is called proton magnetic resonance (PMR) spectra. (CW)|

McQuarrie, Donald A.

1988-01-01

176

Using fMRI to Study Recovery from Acquired Dysphasia  

Microsoft Academic Search

We have used functional magnetic resonance imaging (fMRI) to characterize brain activations associated with two distinct language tasks performed by a 28-year-old woman after partial recovery from dysphasia due to a left frontal hemispheric ischemic stroke. MRI showed that her ischemic lesion extended posteriorly from the left inferior frontal to the perisylvian cortex. fMRI scans of both language tasks revealed

Gemma A. Calvert; Michael J. Brammer; Robin G. Morris; Steve C. R. Williams; Nigel King; Paul M. Matthews

2000-01-01

177

Magnetic Field Issues in Magnetic Resonance Imaging.  

NASA Astrophysics Data System (ADS)

Advances in Magnetic Resonance Imaging depend on the capability of the available hardware. Specifically, for the main magnet configuration, using derivative constraints, we can create a static magnetic field with reduced levels of inhomogeneity over a prescribed imaging volume. In the gradient coil, the entire design for the axial elliptical coil, and the mathematical foundation for the transverse elliptical coil have been presented. Also, the design of a self-shielded cylindrical gradient coil with a restricted length has been presented. In order to generate gradient coils adequate for head imaging without including the human shoulders in the design, asymmetric cylindrical coils in which the gradient center is shifted axially towards the end of a finite cylinder have been introduced and theoretical as well as experimental results have been presented. In order to eliminate eddy current effects in the design of the non-shielded asymmetric gradient coils, the self-shielded asymmetric cylindrical gradient coil geometry has been introduced. Continuing the development of novel geometries for the gradient coils, the complete set of self-shielded cylindrical gradient coils, which are designed such that the x component of the magnetic field varies linearly along the three traditional gradient axes, has been presented. In order to understand the behavior of the rf field inside a dielectric object, a mathematical model is briefly presented. Although specific methods can provide an indication of the rf behavior inside a loosely dielectric object, finite element methodology is the ultimate approach for modeling the human torso and generating an accurate picture for the shape of the rf field inside this dielectric object. For this purpose we have developed a 3D finite element model, using the Coulomb gauge condition as a constraint. Agreement with the heterogeneous multilayer planar model has been established, while agreement with theoretical results from the spherical model and experimental results from the cylindrical model at 170 M H z is very good and provides an encouraging sign for using this finite element approach for modeling the rf inside the human body. (Abstract shortened by UMI.).

Petropoulos, Labros Spiridon

178

Lessons from fMRI about mapping cortical columns  

PubMed Central

Recently-developed functional magnetic resonance imaging (fMRI) can map small functional structures non-invasively and repeatedly without any depth limitation. However, there has been a persistent concern as to whether the high-resolution fMRI signals actually mark the sites of increased neural activity. To examine this outstanding issue, we used iso-orientation columns of isoflurane-anestheized cats as a biological model and confirmed the neural correlation of fMRI iso-orientation maps by comparing with intrinsic optical imaging maps. Our results suggest that highest fMRI signals indeed indicate the sites of increased neuronal activity. Now fMRI can be used to determine plastic and/or developmental change of functional columnar structure possibly on a layer to layer basis. In this review we focus mainly on what technical aspects should be considered when mapping functional cortical columns, including imaging techniques and experimental design.

Kim, Seong-Gi; Fukuda, Mitsuhiro

2008-01-01

179

Graph-partitioned spatial priors for functional magnetic resonance images  

PubMed Central

Spatial models of functional magnetic resonance imaging (fMRI) data allow one to estimate the spatial smoothness of general linear model (GLM) parameters and eschew pre-process smoothing of data entailed by conventional mass-univariate analyses. Recently diffusion-based spatial priors (Harrison et al., 2008) were proposed, which provide a way to formulate an adaptive spatial basis, where the diffusion kernel of a weighted graph-Laplacian (WGL) is used as the prior covariance matrix over GLM parameters. An advantage of these is that they can be used to relax the assumption of isotropy and stationarity implicit in smoothing data with a fixed Gaussian kernel. The limitation of diffusion-based models is purely computational, due to the large number of voxels in a brain volume. One solution is to partition a brain volume into slices, using a spatial model for each slice. This reduces computational burden by approximating the full WGL with a block diagonal form, where each block can be analysed separately. While fMRI data are collected in slices, the functional structures exhibiting spatial coherence and continuity are generally three-dimensional, calling for a more informed partition. We address this using the graph-Laplacian to divide a brain volume into sub-graphs, whose shape can be arbitrary. Their shape depends crucially on edge weights of the graph, which can be based on the Euclidean distance between voxels (isotropic) or on GLM parameters (anisotropic) encoding functional responses. The result is an approximation the full WGL that retains its 3D form and also has potential for parallelism. We applied the method to high-resolution (1mm3) fMRI data and compared models where a volume was divided into either slices or graph-partitions. Models were optimized using Expectation-Maximization and the approximate log-evidence computed to compare these different ways to partition a spatial prior. The real high-resolution fMRI data presented here had greatest evidence for the graph partitioned anisotropic model, which was best able to preserve fine functional detail.

Harrison, LM; Penny, W; Flandin, G; Ruff, CC; Weiskopf, N; Friston, KJ

2009-01-01

180

Magnetic resonance of a single molecular spin  

NASA Astrophysics Data System (ADS)

THE introduction of optical detection methods for observing magnetic resonance transitions in metastable paramagnetic states1-4 has contributed enormously to our understanding of the properties of photoexcited molecules in condensed phases. In such experiments the luminescence intensity is recorded as a function of the frequency of an applied microwave field. At resonance with transitions between sublevels of a metastable paramagnetic state, the lifetime of the metastable state is altered and a consequent change in the luminescence intensity is observed. Here we report the observation of such optically detected magnetic resonance transitions for the triplet state of a single pentacene molecule embedded in a p-terphenyl host crystal. This result has been obtained by combining the conventional optical detection technique for observing magnetic resonance transitions1-4 with the new single-molecule optical detection methods developed recently5,6. This observation opens the way for magnetic resonance studies in condensed phases with single-molecule sensitivity.

Köhler, J.; Disselhorst, J. A. J. M.; Donckers, M. C. J. M.; Groenen, E. J. J.; Schmidt, J.; Moerner, W. E.

1993-05-01

181

Objective perimetry using functional magnetic resonance imaging in patients with visual field loss.  

PubMed

In ophthalmic clinics, subjective perimetry is a standard examination method. However, for certain patients, objective perimetry is useful since it avoids the need for subjective judgments. The purpose of the present study is to demonstrate the feasibility of objective perimetry using functional magnetic resonance imaging (fMRI). fMRI was performed in 8 patients with visual field defects caused by cerebral lesions. The composite stimulus was either the combination of an expanding ring and a clockwise rotating wedge, or a contracting ring and a counter-clockwise rotating wedge. The largest radius was a 10 degrees visual angle with magnifying glasses. The cycle period for the ring and wedge components differed, enabling us to distinguish the two targets within a single time series. Data were analyzed using custom software that interprets the two stimuli and estimates visual field maps. Regions of interest (ROIs) were set covering the entirety of the occipital lobes, and the most effective visual field location for each voxel was calculated from these two response components. The visual field maps obtained with fMRI were compared with the 10-2 Humphrey visual field (HVF) program. While some divergences were observed, in most subjects the visual field defects on fMRI agreed with those on HVF. Cross-correlation coefficients between grayscale values of visual field maps obtained with fMRI and decibel values obtained with HVF were significant (P<0.05) in all subjects. fMRI in conjunction with our method is feasible for objectively and efficiently measuring the visual field of patients with visual field loss. PMID:19348794

Furuta, Ayumu; Nakadomari, Satoshi; Misaki, Masaya; Miyauchi, Satoru; Iida, Tomohiro

2009-04-05

182

Linear constraint minimum variance beamformer functional magnetic resonance inverse imaging  

PubMed Central

Accurate estimation of the timing of neural activity is required to fully model the information flow among functionally specialized regions whose joint activity underlies perception, cognition and action. Attempts to detect the fine temporal structure of task-related activity would benefit from functional imaging methods allowing higher sampling rates. Spatial filtering techniques have been used in magnetoencephalography source imaging applications. In this work, we use the linear constraint minimal variance (LCMV) beamformer localization method to reconstruct single-shot volumetric functional magnetic resonance imaging (fMRI) data using signals acquired simultaneously from all channels of a high density radio-frequency (RF) coil array. The LCMV beamformer method generalizes the existing volumetric magnetic resonance inverse imaging (InI) technique, achieving higher detection sensitivity while maintaining whole-brain spatial coverage and 100 ms temporal resolution. In this paper, we begin by introducing the LCMV reconstruction formulation and then quantitatively assess its performance using both simulated and empirical data. To demonstrate the sensitivity and inter-subject reliability of volumetric LCMV InI, we employ an event-related design to probe the spatial and temporal properties of task-related hemodynamic signal modulations in primary visual cortex. Compared to minimum-norm estimate (MNE) reconstructions, LCMV offers better localization accuracy and superior detection sensitivity. Robust results from both single subject and group analyses demonstrate the excellent sensitivity and specificity of volumetric InI in detecting the spatial and temporal structure of task-related brain activity.

Lin, Fa-Hsuan; Witzel, Thomas; Zeffiro, Thomas A.; Belliveau, John W.

2011-01-01

183

Ethical issues in the clinical application of fMRI: Factors affecting the validity and interpretation of activations  

Microsoft Academic Search

The ability of functional magnetic resonance imaging (fMRI) to localize activations in a single patient, along with the safety and widespread availability of this methodology, has lead to an increasing use of fMRI for clinical purposes such as pre-surgical planning. As methodology continues to improve and more experience with fMRI in the clinical setting is acquired, clinical functional neuroimaging will

John E Desmond; S. H Annabel Chen

2002-01-01

184

Pictures of a thousand words: Investigating the neural mechanisms of reading with extremely rapid event-related fMRI  

Microsoft Academic Search

Reading is one of the most important skills human beings can acquire, but has proven difficult to study naturalistically using functional magnetic resonance imaging (fMRI). We introduce a novel Event-Related Reading (ERR) fMRI approach that enables reliable estimation of the neural correlates of single-word processing during reading of rapidly presented narrative text (200–300ms \\/word). Application to an fMRI experiment in

Tal Yarkoni; Nicole K. Speer; David A. Balota; Mark P. McAvoy; Jeffrey M. Zacks

2008-01-01

185

fMRI resting state networks define distinct modes of long-distance interactions in the human brain  

Microsoft Academic Search

Functional magnetic resonance imaging (fMRI) studies of the human brain have suggested that low-frequency fluctuations in resting fMRI data collected using blood oxygen level dependent (BOLD) contrast correspond to functionally relevant resting state networks (RSNs). Whether the fluctuations of resting fMRI signal in RSNs are a direct consequence of neocortical neuronal activity or are low-frequency artifacts due to other physiological

M. De Luca; C. F. Beckmann; N. De Stefano; P. M. Matthews; S. M. Smith

2006-01-01

186

Childhood maltreatment and response to novel face stimuli presented during functional magnetic resonance imaging in adults.  

PubMed

Facial cues contain important information for guiding social interactions, but not all humans are equally expert at face processing. A number of factors, both genetic and environmental, contribute to differences in face-processing ability. For example, both heritable individual differences in temperament and exposure to childhood maltreatment are associated with alterations in face processing ability and social function. Understanding the neural correlates of alterations in face-processing ability can provide insights into how genetic and environmental risk factors impair social functioning. We examined the association between childhood maltreatment and blood-oxygenation-level-dependent (BOLD) signal as measured in functional magnetic resonance imaging (fMRI) in a group of young adults with an inhibited temperament. We hypothesized that childhood maltreatment exposure would correlate positively with BOLD signal in regions subserving face processing and novelty detection during viewing of novel compared to familiar faces. Functional magnetic resonance imaging (fMRI) degree of exposure to childhood maltreatment was positively correlated with BOLD signal in the bilateral fusiform gyri and the left hippocampus. These fMRI findings suggest that young adults with an inhibited temperament and a history of maltreatment may be particularly vulnerable to neural alterations. These differences could be related to a heightened sensitivity to potential threat-for example, from new people-and may contribute to both the altered social functioning and increased incidence of anxiety disorders in these individuals. PMID:23477839

Edmiston, Elliot Kale; Blackford, Jennifer Urbano

2013-03-07

187

Petal resonator surface coil in spectroscopy by magnetic resonance  

NASA Astrophysics Data System (ADS)

In this work, we present a radio frequency resonator surface coil for Magnetic Resonance Imaging and Spectroscopy based on the magnetron device. We named our RF coil: Petal Resonator Surface (PERES) coil. This resonator coil consists of eight coil petals connected symmetrically all around a central single-loop coil. We previously tested this coil prototype n a General Electric 1.5 T imager and successfully acquired brain images. Based on these encouraging results, we used our coil design on the same MR imager to generate brain spectra. Finally, a MR spectrum of a healthy brain is presented. .

Hidalgo, S.; Rodriguez, A.; Rojas, R.; Sanchez, J.; Reynoso, G.; Barrios, F. A.

2001-10-01

188

Emotional Memory in Early Steroid Abnormalities: An fMRI Study of Adolescents With Congenital Adrenal Hyperplasia  

Microsoft Academic Search

Hormonal imbalances during development may have long-lasting effects. Using functional magnetic resonance imaging (fMRI), we compared 14 youths with Congenital Adrenal Hyperplasia (CAH), a genetic disorder of hormonal dysfunction, with 22 healthy controls on memory encoding of emotional faces. Patients remembered fewer faces than controls, particularly fearful faces. FMRI data to successfully encoded fearful faces revealed that males with CAH

Luigi Mazzone; Sven C. Mueller; Francoise Maheu; Carol VanRyzin; Deborah P. Merke; Monique Ernst

2011-01-01

189

Improving robustness and reliability of phase-sensitive fMRI analysis using temporal off-resonance alignment of single-echo timeseries (TOAST)  

Microsoft Academic Search

Echo Planar Imaging (EPI), often utilized in functional MRI (fMRI) experiments, is well known for its vulnerability to inconsistencies in the static magnetic field (B0). Correction for these field inhomogeneities usually involves measuring the magnetic field at a single time point, and using this static information to correct a series of images collected over the course of one or multiple

Andrew D. Hahn; Andrew S. Nencka; Daniel B. Rowe

2009-01-01

190

Magnetic Resonance Imaging of Glutamate  

PubMed Central

Glutamate (Glu) exhibits a pH and concentration dependent chemical exchange saturation transfer effect (CEST) between its -amine group and bulk water, here termed GluCEST. GluCEST asymmetry is observed at ~3 parts per million downfield from bulk water. Following middle cerebral artery occlusion in the rat brain, an approximately 100% elevation of GluCEST in the ipsilateral side compared to the contralateral side was observed, and is predominantly due to pH changes. In a rat brain tumor model with blood brain barrier disruption, intravenous Glu injection resulted in a clear elevation of GluCEST and a comparable increase in the proton magnetic resonance spectroscopy signal of Glu. GluCEST maps from healthy human brain at 7T were also obtained. These results demonstrate the feasibility and potential of GluCEST for mapping relative changes in Glu concentration as well as pH in vivo. Potential contributions from other brain metabolites to the GluCEST effect are also discussed.

Cai, Kejia; Haris, Mohammad; Singh, Anup; Kogan, Feliks; Greenberg, Joel H.; Hariharan, Hari; Detre, John A.; Reddy, Ravinder

2011-01-01

191

Detecting spin perturbations using magnetic resonance imaging  

US Patent & Trademark Office Database

Implementations and examples of systems, apparatus and techniques for using magnetic resonance imaging to measure spin perturbations. In one implementation, a sample containing nuclear spins is magnetized using a principle magnetic field generated external to the sample. A periodic pulse sequence is applied to the sample. The pulse sequence includes multiple radio frequency (rf) pulses and multiple recovery times between the rf pulses. The pulse sequence is configured to generate, in the presence of a magnetic field perturbation, a sequence of multiple different steady states of magnetization in the sample during each period of the pulse sequence. A magnetic resonance signal acquired from the sample is processed to identify characteristics of a magnetic field perturbation in the sample. In some implementations, processing the signal to identify characteristics of a magnetic field perturbation in the sample includes processing the signal to identify characteristics of an electric current in the sample.

2012-08-21

192

Surface-based analysis methods for high-resolution functional magnetic resonance imaging  

PubMed Central

Functional magnetic resonance imaging (fMRI) has become a popular technique for studies of human brain activity. Typically, fMRI is performed with >3-mm sampling, so that the imaging data can be regarded as two-dimensional samples that average through the 1.5—4-mm thickness of cerebral cortex. The increasing use of higher spatial resolutions, <1.5-mm sampling, complicates the analysis of fMRI, as one must now consider activity variations within the depth of the brain tissue. We present a set of surface-based methods to exploit the use of high-resolution fMRI for depth analysis. These methods utilize white-matter segmentations coupled with deformable-surface algorithms to create a smooth surface representation at the gray-white interface and pial membrane. These surfaces provide vertex positions and normals for depth calculations, enabling averaging schemes that can increase contrast-to-noise ratio, as well as permitting the direct analysis of depth profiles of functional activity in the human brain.

Khan, Rez; Zhang, Qin; Darayan, Shayan; Dhandapani, Sankari; Katyal, Sucharit; Greene, Clint; Bajaj, Chandra; Ress, David

2011-01-01

193

Magnetic Resonance at Short Distances  

SciTech Connect

The magnetic interactions between a fermion and an antifermion of opposite electric or color charges in the $^{1}S_{0}^{-+}$ and $^{3}P_{0}^{++}$ states with $J=0$ are very attractive and singular near the origin and may allow the formation of new bound and resonance states at short distances. In the two body Dirac equations formulated in constraint dynamics, the short-distance attraction for these states for point particles leads to a quasipotential that behaves near the origin as $-\\alpha ^{2}/r^{2}$, where $ \\alpha $ is the coupling constant. Representing this quasipotential at short distances as $\\lambda (\\lambda +1)/r^{2}$ with $\\lambda =(-1+\\sqrt{1-4\\alpha ^{2}})/2$, both $^{1}S_{0}^{-+}$ and $^{3}P_{0}^{++}$ states admit two types of eigenstates with drastically different behaviors for the radial wave function $u=r\\psi $. One type of states, with $u$ growing as $r^{\\lambda +1}$ at small $r$, will be called usual states. The other type of states with $u$ growing as $r^{-\\lambda }$ will be called peculiar states. Both of the usual and peculiar eigenstates have admissible behaviors at short distances. Remarkably, the solutions for both sets of $^{1}S_{0}$ states can be written out analytically. The usual bound $^{1}S_{0}$ states possess attributes the same as those one usually encounters in QED and QCD, with bound state energies explicitly agreeing with the standard perturbative results through order $\\alpha ^{4}$. In contrast, the peculiar bound $^{1}S_{0}$ states, yet to be observed, not only have different behaviors at the origin, but also distinctly different bound state properties (and scattering phase shifts). For the peculiar $^{1}S_{0}$ ground state of fermion-antifermion pair with fermion rest mass $m$, the root-mean-square radius is approximately $1/m$, binding energy is approximately $(2-\\sqrt{2})m$, and rest mass approximately $\\sqrt{2}m$. On the other hand, the $(n+1)$${}^{1}S_{0}$ peculiar state with principal quantum number $(n+1)$ is nearly degenerate in energy and approximately equal in size with the $n$$^{1}S_{0}$ usual states. For the $ {}^{3}P_{0}$ states, the usual solutions lead to the standard bound state energies and no resonance, but resonances have been found for the peculiar states whose energies depend on the description of the internal structure of the charges, the mass of the constituent, and the coupling constant. The existence of both usual and peculiar eigenstates in the same system leads to the non-self-adjoint property of the mass operator and two non-orthogonal complete sets. As both sets of states are physically admissible, the mass operator can be made self-adjoint with a single complete set of admissible states by introducing a new peculiarity quantum number and an enlarged Hilbert space that contains both the usual and peculiar states in different peculiarity sectors. Whether or not these newly-uncovered quantum-mechanically acceptable peculiar $^{1}S_{0}$ bound states and $^{3}P_{0}$ resonances for point fermion-antifermion systems correspond to physical states remains to be further investigated.

Crater, H. W. [University of Tennessee Space Institute; Wong, Cheuk-Yin [ORNL

2012-01-01

194

Negative socio-emotional resonance in schizophrenia: a functional magnetic resonance imaging hypothesis.  

PubMed

The aim of the present study is to use neuroscience theories about brain function (mirror-neurons MN) to draw inferences about the mechanisms supporting emotional resonance in two different groups of schizophrenia patients (with flat affect FA+ n = 13 and without flat affect FA- n = 11). We hypothesize that FA+ will not activate key brain areas involved in emotional processing. Conversely, FA- will have a functional mirror system for emotional resonance confirmed by activation of the prefrontal cortex and behavioral results. To test this hypothesis, we compared the two groups using blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) displaying a passive visual task (44 negative IAPS pictures and 44 neutral pictures). A random-effects analysis, for schizophrenia patients FA-, revealed significant loci of activation in the left mesial prefrontal (MPFC), right orbitofrontal (OFC) and left anterior cingulate cortices (ACC). Correlational analyses carried out between self-report ratings of negative feelings and BOLD signal changes revealed the existence of positive correlation in the LACC, LMPFC and ROFC. Conversely, FA+ did not show significant activation in the prefrontal cortex. We propose that negative emotional resonance induced by passively viewing negative pictures may be a form of "mirroring" that grounds negative feelings via an experiential mechanism. Hence, it could be argued that FA- were able to 'feel' emotions through this resonance behavior. Conversely, we suggest that the dysfunction seen in the FA+ group is a failure or distortion in the development of the MN system. This could be due to genetic or other endogenous causes, which affected prefrontal cortex MN involved in emotional resonance. PMID:15288371

Fahim, C; Stip, E; Mancini-Marïe, A; Boualem, M; Malaspina, D; Beauregard, M

2004-01-01

195

Miniature Magnet for Electron Spin Resonance Experiments  

ERIC Educational Resources Information Center

|Describes commercially available permanent magnets that have been incorporated in a compact and inexpensive structure providing both field sweep and modulation suitable for electron spin resonance at microwave frequencies. (MLH)|

Rupp, L. W.; And Others

1976-01-01

196

Magnetic Resonance Imaging Studies of Process Rheology.  

National Technical Information Service (NTIS)

The objective of this program is to develop magnetic resonance imaging and numerical modeling methods which will provide for improved methods of flow analysis as well as an improved understanding of the flow behavior of solid particle filled polymeric sus...

D. T. Wadiac G. A. Lo J. C. Crowley R. Van De Griend S. W. Sinton

1988-01-01

197

JAMA Patient Page: Magnetic Resonance Imaging  

MedlinePLUS

... Radiology; National Library of Medicine; International Society for Magnetic Resonance in Medicine; National Heart, Lung, and Blood Institute; Radiological Society of North America The JAMA Patient Page is a public ...

198

Miniature Magnet for Electron Spin Resonance Experiments  

ERIC Educational Resources Information Center

Describes commercially available permanent magnets that have been incorporated in a compact and inexpensive structure providing both field sweep and modulation suitable for electron spin resonance at microwave frequencies. (MLH)

Rupp, L. W.; And Others

1976-01-01

199

Magnetic Earth Ionosphere Resonant Frequencies (MEIRF) Project.  

National Technical Information Service (NTIS)

The West Virginia State College Community College Division NASA Magnetic Earth Ionosphere Resonant Frequencies (MEIRF) study is described. During this contract period, the two most significant and professionally rewarding events were the presentation of t...

C. Spaniol

1993-01-01

200

Coronary computed tomography and magnetic resonance imaging.  

PubMed

Cardiac computed tomography and magnetic resonance are relatively new imaging modalities that can exceed the ability of established imaging modalities to detect present pathology or predict patient outcomes. Coronary calcium scoring may be useful in asymptomatic patients at intermediate risk. Computed tomographic coronary angiography is a first-line indication to evaluate congenitally abnormal coronary arteries and, along with stress magnetic resonance myocardial perfusion imaging, is useful in symptomatic patients with nondiagnostic conventional stress tests. Cardiac magnetic resonance is indicated for visualizing cardiac structure and function, and delayed enhancement magnetic resonance is a first-line indication for assessing myocardial viability. Imaging plaque and molecular mechanisms related to plaque rupture holds great promise for the presymptomatic detection of patients at risk for coronary events but is not yet suitable for routine clinical use. PMID:19269527

Kantor, Birgit; Nagel, Eike; Schoenhagen, Paul; Barkhausen, Jörg; Gerber, Thomas C

2009-04-01

201

Coronary Computed Tomography and Magnetic Resonance Imaging  

PubMed Central

Cardiac computed tomography and magnetic resonance are relatively new imaging modalities that can exceed the ability of established imaging modalities to detect present pathology or predict patient outcomes. Coronary calcium scoring may be useful in asymptomatic patients at intermediate risk. Computed tomographic coronary angiography is a first-line indication to evaluate congenitally abnormal coronary arteries and, along with stress magnetic resonance myocardial perfusion imaging, is useful in symptomatic patients with nondiagnostic conventional stress tests. Cardiac magnetic resonance is indicated for visualizing cardiac structure and function, and delayed enhancement magnetic resonance is a first-line indication for assessing myocardial viability. Imaging plaque and molecular mechanisms related to plaque rupture holds great promise for the presymptomatic detection of patients at risk for coronary events but is not yet suitable for routine clinical use.

Kantor, Birgit; Nagel, Eike; Schoenhagen, Paul; Barkhausen, Jorg; Gerber, Thomas C.

2009-01-01

202

Pocket atlas of cranial magnetic resonance imaging  

SciTech Connect

This atlas illustrates normal cerebral anatomy in magnetic resonance images. From their studies in cerebral anatomy utilizing cryomicrotome and other techniques, the authors selected more than 100 high-resolution images that represent the most clinically useful scans.

Haughton, V.M.; Daniels, D.L.

1986-01-01

203

Magnetic Resonance Spectroscopy of Breast Disease.  

National Technical Information Service (NTIS)

We have developed a unique magnetic resonance imaging multi voxel pulse sequence producing spectroscopic images of key metabolites found in breast cancer, and validated our work with in vitro spectra and pathology. We have shown that choline peaks are oft...

D. M. Ikeda

2001-01-01

204

Magnetic Resonance Spectroscopy of Breast Cancer.  

National Technical Information Service (NTIS)

We have developed a unique magnetic resonance imaging multi voxel pulse sequence unaffected by intravenous contrast producing spectroscopic images of key metabolites (choline) found in breast cancer, and validated our work in 22 breast lesions with in vit...

D. M. Ikeda

2002-01-01

205

From Signal to Image: Magnetic Resonance Imaging Physics for Cardiac Magnetic Resonance  

Microsoft Academic Search

.   Magnetic resonance imaging (MRI) is a powerful tool which enables the visualization of anatomy and the assessment of many\\u000a physiological aspects of organ function. MRI and magnetic resonance angiography and magnetic resonance spectroscopy will play\\u000a critical roles in cardiac applications during the next millennium. Thus, it is important to have a basic understanding of\\u000a the most important physical processes

R. V. Mulkern; T. Chung

2000-01-01

206

Can magnetic resonance imaging differentiate undifferentiated arthritis?  

PubMed Central

A high sensitivity for the detection of inflammatory and destructive changes in inflammatory joint diseases makes magnetic resonance imaging potentially useful for assigning specific diagnoses, such as rheumatoid arthritis and psoriatic arthritis in arthritides, that remain undifferentiated after conventional clinical, biochemical and radiographic examinations. With recent data as the starting point, the present paper describes the current knowledge on magnetic resonance imaging in the differential diagnosis of undifferentiated arthritis.

?stergaard, Mikkel; Duer, Anne; H?rslev-Petersen, Kim

2005-01-01

207

Reducing the Effects of Background Noise during Auditory Functional Magnetic Resonance Imaging of Speech Processing: Qualitative and Quantitative Comparisons between Two Image Acquisition Schemes and Noise Cancellation  

ERIC Educational Resources Information Center

|Purpose: The intense sound generated during functional magnetic resonance imaging (fMRI) complicates studies of speech and hearing. This experiment evaluated the benefits of using active noise cancellation (ANC), which attenuates the level of the scanner sound at the participant's ear by up to 35 dB around the peak at 600 Hz. Method: Speech and…

Blackman, Graham A.; Hall, Deborah A.

2011-01-01

208

Activation of human language processing brain regions after the presentation of random letter strings demonstrated with event-related functional magnetic resonance imaging  

Microsoft Academic Search

This study addresses the question, to what extent the processing of meaningless random letter strings involves classical language related brain regions. Using event-related functional magnetic resonance imaging (fMRI), which allows random stimulus presentation, we could demonstrate activation in the left inferior frontal gyrus, the left superior temporal gyrus, left parietal and occipital regions after the presentation of random letter strings

Frank Jessen; Michael Erb; Uwe Klose; Martin Lotze; Wolfgang Grodd; Reinhard Heun

1999-01-01

209

Level of sustained entorhinal activity at study correlates with subsequent cued-recall performance: A functional magnetic resonance imaging study with high acquisition rate  

Microsoft Academic Search

Functional magnetic resonance imaging (fMRI) with high acquisition rate was performed during the intentional memorizing of words to specify which medial temporal lobe structure is important in determining what words are subsequently remembered in a cued-recall test and to characterize the time course of activation in that structure. Functional images of six healthy young subjects were analyzed by two subject-

James B. Brewer; Zuo Zhao; Gary H. Glover; John D. E. Gabrieli

1999-01-01

210

Resonant Magnetic Field Sensor With Frequency Output  

Microsoft Academic Search

This paper presents a novel type of resonant magnetic field sensor exploiting the Lorentz force and providing a frequency output. The mechanical resonator, a cantilever structure, is embedded as the frequency-determining element in an electrical oscillator. By generating an electrical current proportional to the position of the cantilever, a Lorentz force acting like an additional equivalent spring is exerted on

Robert Sunier; Tobias Vancura; Yue Li; Kay-Uwe Kirstein; Henry Baltes; Oliver Brand

2006-01-01

211

Force-Detected Nuclear Magnetic Resonance Probe  

NASA Astrophysics Data System (ADS)

Magnetic resonance force microscopy (MRFM) entails measuring the force on spins in a sample by a nearby magnetic grain as they are cyclically flipped by RF radiation in the presence of a background magnetic field. The sample is glued to a cantilever, which acts as the force detector. We have constructed a compact, LHe-cooled MRFM probe which fits in a 1'' tube, minimizing thermal drift, and allowing testing in storage dewars. The RF field is generated by a 700 ?m diameter coil in a tuned and matched tank circuit. Joule and RF heating control sample temperature. The sample is mounted on a silicon-nitride cantilever, and its magnetization is modulated at the cantilever resonance frequency by interrupted adiabatic rapid passage. Probe performance is demonstrated by measuring a 10 fN magnetic resonance signal from a sample of Nd doped Ca^19F_2.

Harrell, Lee E.; Thurber, Kent; Fainchtein, Raul; Marohn, John A.; Smith, Doran D.

2000-03-01

212

Magnetic resonance measurements of polar sea ice  

Microsoft Academic Search

A Nuclear Magnetic Resonance (NMR) sensor system has been developed to measure the brine fraction profile of polar sea ice. The system is based on a 0.3 T Halbach permanent magnet array and has significantly more sensitivity than earlier Earth's field NMR systems deployed in Antarctica. Brine fraction experiments were performed in November 2009 near Ross Island, Antarctica and the

Robin Dykstra; Achim Gadke

2011-01-01

213

Helmholtz superconducting receivers for magnetic resonance microscopy  

Microsoft Academic Search

The use of coupled high temperature superconductor (HTS) coil arrays in construction of low noise volume imaging probes for magnetic resonance is investigated. Two probes designed to image different sample volumes were developed in collaboration with Conductus Inc. The design objectives were (1)a robust vacuum system, (2)increased signal to noise performance over copper imaging probes, and (3)improved magnetic field homogeneity

Sarah Elizabeth Hurlston

2000-01-01

214

The role of the posterior parietal cortex in human object recognition: a functional magnetic resonance imaging study  

Microsoft Academic Search

The mechanisms involved in visual object recognition from non-canonical viewpoints were investigated using functional magnetic resonance imaging (fMRI). We used a passive observation task and found three areas activated more strongly in the non-canonical viewing condition compared with the canonical viewing condition. First, it was found that the fusiform gyrus and posterior part of the inferior temporal cortex were involved

Takeshi Sugio; Toshio Inui; Kayako Matsuo; Masako Matsuzawa; G. H Glover; Toshiharu Nakai

1999-01-01

215

Hippocampal functional magnetic resonance imaging during a face–name learning task in adolescents with antecedents of prematurity  

Microsoft Academic Search

Functional magnetic resonance imaging (fMRI) was used to map hippocampal activation during a declarative memory task in a sample of 14 adolescents with antecedents of prematurity (AP). The sample with AP was matched by age, sex and handedness with 14 full-term controls with no history of neurological or psychiatric illness. The target task consisted in learning 16 novel face–name pairs,

Mónica Giménez; Carme Junqué; Pere Vendrell; Xavier Caldú; Ana Narberhaus; Núria Bargalló; Carles Falcón; Francesc Botet; Josep Maria Mercader

2005-01-01

216

Functional Magnetic Resonance Imaging of Compensatory Neural Recruitment in Aging and Risk for Alzheimer’s Disease: Review and Recommendations  

Microsoft Academic Search

There has been a recent proliferation of functional magnetic resonance imaging (fMRI) studies that interpret between-group or within-group differences in brain response patterns as evidence for compensatory neural recruitment. However, it is currently a challenge to determine whether these observed differences are truly attributable to compensatory neural recruitment or whether they are indicative of some other cognitive or physiological process.

S. Duke Han; Katherine J. Bangen; Mark W. Bondi

2009-01-01

217

Sevoflurane 0.25 MAC Preferentially Affects Higher Order Association Areas: A Functional Magnetic Resonance Imaging Study in Volunteers  

Microsoft Academic Search

BACKGROUND: Functional magnetic resonance imaging (fMRI) can objectively mea- sure the subjective effects of anesthesia. Memory-related regions (association areas) are affected by subanesthetic doses of volatile anesthetics. In this study we measured the regional neuronal effects of 0.25 MAC sevoflurane in healthy volunteers and differentiated the effect between primary cortical regions and association areas. METHODS: The effect of 0.25 MAC

Ramachandran Ramani; Maolin Qiu; Robert Todd Constable

2007-01-01

218

Quantitative Comparison of Functional Magnetic Resonance Imaging with Positron Emission Tomography Using a Force-Related Paradigm  

Microsoft Academic Search

The intention of our study was to compare functional magnetic resonance imaging (fMRI) with positron emission tomography (PET). We used the same force-related motor paradigm for both techniques, which allows for quantification of stimulus intensity. Regional cerebral blood flow (rCBF) was determined with PET in six male subjects (age 30±3) using the slow bolus injection technique and oxygen-15-labeled water. Scans

Christian Dettmers; Alan Connelly; Klaus M Stephan; Robert Turner; Karl J Friston; Richard S. J Frackowiak; David G Gadian

1996-01-01

219

Nanoscale Fourier-Transform Magnetic Resonance Imaging  

NASA Astrophysics Data System (ADS)

We report a method for nanometer-scale pulsed nuclear magnetic resonance imaging and spectroscopy. Periodic radio-frequency pulses are used to create temporal correlations in the statistical polarization of a solid organic sample. The spin density is spatially encoded by applying a series of intense magnetic field gradient pulses generated by focusing electric current through a nanometer-scale metal constriction. We demonstrate this technique using a silicon nanowire mechanical oscillator as a magnetic resonance sensor to image H1 spins in a polystyrene sample. We obtain a two-dimensional projection of the sample proton density with approximately 10-nm resolution.

Nichol, John M.; Naibert, Tyler R.; Hemesath, Eric R.; Lauhon, Lincoln J.; Budakian, Raffi

2013-07-01

220

Magnetic resonance based noninvasive RF nerve stimulator.  

PubMed

A noninvasive method of stimulating the nerve by applying radiofrequency has been presented. The design is based on the concept of magnetic resonance based power transfer. A comparison between electric field on the nerve at the frequency of 450-550 KHz with vacuum placed under a human tissue and the case where it is replaced with a resonant and non-resonant structure was analysed. Calculations were performed by using Ansoft HFSS. Power savings of 7.15% was observed when resonant structures were used, compared to vacuum. Theoretical calculation and simulation of fields were presented. PMID:23367443

Ganesh Bharadwaj, C V; Yuanjin, Zheng

2012-01-01

221

HOSPITAL PHYSICS: Magnetic resonance imaging and spectroscopy  

NASA Astrophysics Data System (ADS)

Nuclear Magnetic Resonance (NMR) was first described in the scientific literature 50 years ago when Bloch and Purcell, working independently, showed how certain nuclei placed in a magnetic field absorbed energy in the radiofrequency range and re-emitted this energy during their transition back to the relaxed state (Bloch 1946, Purcell 1946). This phenomenon has since revolutionized medical imaging with its application in Magnetic Resonance Imaging (MRI) and in vivo Magnetic Resonance Spectroscopy (MRS). MRI produces pictures of `slices' through the human body with exquisite detail and contrast without the use of radiation, while in vivo MRS provides chemical information from selected areas in a similarly non-invasive way. This article describes some of the principles involved in the two techniques.

Andrews, Caroline; Simmons, Andrew; Williams, Steve

1996-03-01

222

Magnetically-excited flexural plate wave resonator  

SciTech Connect

A flexural plate wave (FPW) resonator was constructed by patterning current lines on a silicon nitride membrane suspended on a rectangular silicon frame. Eigenmodes of the rectangular membrane were excited using Lorentz forces generated between alternating surface currents and a static in-plane magnetic field. The magnetic field strength required for these devices can be achieved with small permanent magnets ({approx} 1 cm{sup 3}). Preferential coupling to a particular membrane mode was achieved by positioning current lines along longitudinal mode antinodes. An equivalent-circuit model was derived that characterizes the input impedance of a one-port device and the transmission response of a two-port device over a range of frequencies near a single membrane resonance. Experiments were performed to characterize the effects of varying magnetic field, ambient gas, gas pressure, and input power. To the authors` knowledge, this is the first experimental demonstration of a resonant FPW device.

Martin, S.J.; Butler, M.A.; Spates, J.J.; Schubert, W.K.; Mitchell, M.A. [Sandia National Labs., Albuquerque, NM (United States). Microsensor Research and Development Dept.

1997-08-01

223

Solution nuclear magnetic resonance spectroscopy.  

PubMed

Solution nuclear magnetic resonance (NMR) spectroscopy has come a long way in characterizing the structure and function of biological molecules since the first one-dimensional spectrum of protein was recorded about 30 years ago. To date (September 1, 2012), there are 9,521 solution NMR structures in the Protein Data Bank, compared to 74,009 determined by crystallographic methods. Unlike X-ray and electron microscopy (EM) methods, which are based on the concepts of Fourier optics and image reconstruction, structure determination by NMR involves measuring structural restraints and finding structural solutions that satisfy the restraints. Although the NMR approach is much less direct in a physical sense, it has proven itself over the years to be capable of de novo structure determination at high precision. Moreover, the method is highly versatile and can be used in a variety of ways for addressing mechanistic questions. NMR measurements of protein internal dynamics and protein-protein or protein-ligand interaction are directly relevant to function in vivo because the molecules are often in physiological buffer conditions. The method can also be applied to investigate protein-folding intermediates, conformational changes, as well as intrinsically unfolded proteins. Recently, along with X-ray and EM, solution NMR has entered a state of rapid growth for structural studies of membrane proteins, already demonstrating its feasibility in de novo structure determination of membrane-embedded ion channels and receptors. As the hardware advances rapidly, especially in cryogenic probes that have much higher sensitivity, the sample concentration required for solution NMR investigation is decreasing, hopefully soon to a concentration level at which nonspecific protein aggregation is no longer an issue. After three decades of improvement in spectrometer technology, NMR pulse experiments, isotope labeling schemes, and structure determination software, we believe that solution NMR will truly enter the production phase in the next decade to answer biological questions of high impact, and to become more versatile than ever in complementing X-ray and EM in investigating protein structure and function. PMID:23132077

Chou, James J; Sounier, Remy

2013-01-01

224

Nuclear magnetic resonance apparatus for pulsed high magnetic fields  

NASA Astrophysics Data System (ADS)

A nuclear magnetic resonance apparatus for experiments in pulsed high magnetic fields is described. The magnetic field pulses created together with various magnet coils determine the requirements such an apparatus has to fulfill to be operated successfully in pulsed fields. Independent of the chosen coil it is desirable to operate the entire experiment at the highest possible bandwidth such that a correspondingly large temporal fraction of the magnetic field pulse can be used to probe a given sample. Our apparatus offers a bandwidth of up to 20 MHz and has been tested successfully at the Hochfeld-Magnetlabor Dresden, even in a very fast dual coil magnet that has produced a peak field of 94.2 T. Using a medium-sized single coil with a significantly slower dependence, it is possible to perform advanced multi-pulse nuclear magnetic resonance experiments. As an example we discuss a Carr-Purcell spin echo sequence at a field of 62 T.

Meier, Benno; Kohlrautz, Jonas; Haase, Jürgen; Braun, Marco; Wolff-Fabris, Frederik; Kampert, Erik; Herrmannsdörfer, Thomas; Wosnitza, Joachim

2012-08-01

225

Magnetic Resonance Imaging and Magnetic Resonance Cholangiopancreatography of Intraductal Papillary Mucinous Tumor of the Pancreas  

Microsoft Academic Search

- lary mucinous tumor (IPMT) of the pancreas on magnetic resonance imaging (MRI) and magnetic resonance cholangiopancreatography (MRCP) and to propose a guide for its optimal management based on the characteristic imaging findings. Sixteen patients with pathologically-proven IPMT are included in the study. All patients under - went MRI and MRCP. The imaging features were retrospectively reviewed and correlated with

Chih-hui Lee; Ta-sen Yeh; Jeng-Hwei Tseng

2006-01-01

226

Prolonged survival and serial magnetic resonance imaging/magnetic resonance spectroscopy changes in infantile Krabbe disease.  

PubMed

Krabbe disease may present during infancy, late infancy, or adulthood. Earlier-onset disease is associated with shorter survival times. We present a case of infantile onset Krabbe disease with prolonged survival, initial intracranial optic nerves and optic chiasm hypertrophy, and serial changes on cranial magnetic resonance imaging and magnetic resonance spectroscopy. PMID:22964446

Udow, Sean; Bunge, Martin; Ryner, Lawrence; Mhanni, Aizeddin A; Salman, Michael S

2012-10-01

227

Diffusion-based spatial priors for functional magnetic resonance images  

PubMed Central

We recently outlined a Bayesian scheme for analyzing fMRI data using diffusion-based spatial priors [Harrison, L.M., Penny, W., Ashburner, J., Trujillo-Barreto, N., Friston, K.J., 2007. Diffusion-based spatial priors for imaging. NeuroImage 38, 677–695]. The current paper continues this theme, applying it to a single-subject functional magnetic resonance imaging (fMRI) study of the auditory system. We show that spatial priors on functional activations, based on diffusion, can be formulated in terms of the eigenmodes of a graph Laplacian. This allows one to discard eigenmodes with small eigenvalues, to provide a computationally efficient scheme. Furthermore, this formulation shows that diffusion-based priors are a generalization of conventional Laplacian priors [Penny, W.D., Trujillo-Barreto, N.J., Friston, K.J., 2005. Bayesian fMRI time series analysis with spatial priors. NeuroImage 24, 350–362]. Finally, we show how diffusion-based priors are a special case of Gaussian process models that can be inverted using classical covariance component estimation techniques like restricted maximum likelihood [Patterson, H.D., Thompson, R., 1974. Maximum likelihood estimation of components of variance. Paper presented at: 8th International Biometrics Conference (Constanta, Romania)]. The convention in SPM is to smooth data with a fixed isotropic Gaussian kernel before inverting a mass-univariate statistical model. This entails the strong assumption that data are generated smoothly throughout the brain. However, there is no way to determine if this assumption is supported by the data, because data are smoothed before statistical modeling. In contrast, if a spatial prior is used, smoothness is estimated given non-smoothed data. Explicit spatial priors enable formal model comparison of different prior assumptions, e.g., that data are generated from a stationary (i.e., fixed throughout the brain) or non-stationary spatial process. Indeed, for the auditory data we provide strong evidence for a non-stationary process, which concurs with a qualitative comparison of predicted activations at the boundary of functionally selective regions.

Harrison, L.M.; Penny, W.; Daunizeau, J.; Friston, K.J.

2008-01-01

228

Impaired inhibitory control in 'internet addiction disorder': a functional magnetic resonance imaging study.  

PubMed

'Internet addiction disorder' (IAD) is rapidly becoming a prevalent mental health concern in many countries around the world. The neurobiological underpinnings of internet addiction should be studied to unravel the potential heterogeneity in the disorder. The present study examines the neural correlates of response inhibition in males with and without IAD using an event-related functional magnetic resonance imaging (fMRI) Stroop task. The IAD group demonstrated significantly greater 'Stroop effect'-related activity in the anterior and posterior cingulate cortices compared with their healthy peers. These results may suggest diminished efficiency of response-inhibition processes in the IAD group relative to healthy controls. PMID:22892351

Dong, Guangheng; Devito, Elise E; Du, Xiaoxia; Cui, Zhuoya

2012-08-12

229

A method for anisotropic spatial smoothing of functional magnetic resonance images using distance transformation of a structural image.  

PubMed

Spatial smoothing using isotropic Gaussian kernels to remove noise reduces spatial resolution and increases the partial volume effect of functional magnetic resonance images (fMRI), thereby reducing localization power. To minimize these limitations, we propose a novel anisotropic smoothing method for fMRI data. To extract an anisotropic tensor for each voxel of the functional data, we derived an intensity gradient using the distance transformation of the segmented gray matter of the fMRI-coregistered T1-weighted image. The intensity gradient was then used to determine the anisotropic smoothing kernel at each voxel of the fMRI data. Performance evaluations on both real and simulated data showed that the proposed method had 10% higher statistical power and about 20% higher gray matter localization compared to isotropic smoothing and robustness to the registration errors (up to 4 mm translations and 4° rotations) between T1 structural images and fMRI data. The proposed method also showed higher performance than the anisotropic smoothing with diffusion gradients derived from the fMRI intensity data. PMID:21772082

Nam, Haewon; Lee, Dongha; Lee, Jong Doo; Park, Hae-Jeong

2011-07-19

230

Evaluation of the Effectiveness of Pregabalin in Alleviating Pain Associated with Fibromyalgia: Using Functional Magnetic Resonance Imaging Study  

PubMed Central

Purpose To assess the efficacy of pregabalin by showing differences in the neuronal activities of fibromyalgia (FM) patients before and after longitudinal treatment using functional magnetic resonance imaging (fMRI). Materials and Methods In total, 21 female patients with FM and 11 age- and gender-matched healthy controls participated. FM patients underwent fMRI at baseline and following pharmacological therapy with pregabalin to diminish their pain. Pressure-pain stimuli were delivered on the subject’s thumbnail bed during fMRI scans. Brain activation regions in fMRI were evaluated for longitudinal changes using a paired t-test. Changes in clinical features were also assessed with the Fibromyalgia Impact Questionnaire (FIQ), Brief Fatigue Inventory (BFI), Beck Depression Inventory (BDI), Widespread Pain Index (WPI), Symptom Severity Scale Score (SSS), and State-Trait Anxiety Inventory (STAI). Results Clinical scores were reduced significantly following therapy with five of the six clinical tests (FIQ, BFI, BDI, WPI, SSS; p < 0.05). Brain activation post-treatment was significantly lower than that pre-treatment in 13 regions of the brain (p < 0.001). Conclusions Our findings confirm that pregabalin influences aspects of the whole pain matrix, using fMRI, inducing longitudinal changes in neuronal activity during the pain state, and that it reduces pain and other core symptoms of FM. This method could be applied to other longitudinal clinical trials of pharmacological treatments for FM.

Kim, Seong-Ho; Lee, Youngho; Lee, Sunggun; Mun, Chi-Woong

2013-01-01

231

Magnetic resonance of a single molecular spin  

NASA Astrophysics Data System (ADS)

Magnetic-resonance spectroscopy on single molecules represents the ultimate limit in sensitivity of electron spin resonance: the detection of a single molecular spin. This is achieved by combining single molecule spectroscopy and optically detected magnetic resonance. Experimental results on pentacene in p-terphenyl both in zero-field and in the presence of a weak magnetic field demonstrate that magnetic-resonance spectroscopy on single molecules adds on to the specificity of single-molecule spectroscopy. It proved possible to identify single molecules which contain 13C nuclei in natural abundance and to observe the splitting of the electron spin resonance line resulting from the hyperfine intercation of a single molecular spin with a single 13C nuclear spin. From the Zeeman effect the orientation of the symmetry axes of individual molecules with respect to the direction of the external magnetic field is obtained. This allows to compare the orientation of individual molecules with their substitutional-site specific transition frequencies depending on the quality of the host crystal.

Köhler, Jürgen

1999-03-01

232

Magnetic material arrangement in oriented termites: a magnetic resonance study  

NASA Astrophysics Data System (ADS)

Temperature dependence of the magnetic resonance is used to study the magnetic material in oriented Neocapritermes opacus (N.o.) termite, the only prey of the migratory ant Pachycondyla marginata (P.m.). A broad line in the g=2 region, associated to isolated nanoparticles shows that at least 97% of the magnetic material is in the termite's body (abdomen+thorax). From the temperature dependence of the resonant field and from the spectral linewidths, we estimate the existence of magnetic nanoparticles 18.5+/-0.3nm in diameter and an effective magnetic anisotropy constant, Keff between 2.1 and 3.2×104erg/cm3. A sudden change in the double integrated spectra at about 100K for N.o. with the long body axis oriented perpendicular to the magnetic field can be attributed to the Verwey transition, and suggests an organized film-like particle system.

Alves, O. C.; Wajnberg, E.; de Oliveira, J. F.; Esquivel, D. M. S.

2004-06-01

233

Temporal Feature Selection for fMRI Analysis  

Microsoft Academic Search

Recent work in neuroimaging has shown that it is possible to classify cognitive states from functional magnetic resonance images (fMRI). Machine learning classifiers such as Gaus- sian Naive Bayes, Support Vector Machines, and Nearest Neighbors have all been applied successfully to this domain. Although it is a natural question to ask which classifiers work best, research has shown that the

Mark Palatucci

234

Optimization of Blocked Designs in fMRI Studies  

ERIC Educational Resources Information Center

|Blocked designs in functional magnetic resonance imaging (fMRI) are useful to localize functional brain areas. A blocked design consists of different blocks of trials of the same stimulus type and is characterized by three factors: the length of blocks, i.e., number of trials per blocks, the ordering of task and rest blocks, and the time between…

Maus, Barbel; van Breukelen, Gerard J. P.; Goebel, Rainer; Berger, Martijn P. F.

2010-01-01

235

Optimization of Blocked Designs in fMRI Studies  

ERIC Educational Resources Information Center

Blocked designs in functional magnetic resonance imaging (fMRI) are useful to localize functional brain areas. A blocked design consists of different blocks of trials of the same stimulus type and is characterized by three factors: the length of blocks, i.e., number of trials per blocks, the ordering of task and rest blocks, and the time between…

Maus, Barbel; van Breukelen, Gerard J. P.; Goebel, Rainer; Berger, Martijn P. F.

2010-01-01

236

Unified SPM–ICA for fMRI analysis  

Microsoft Academic Search

A widely used tool for functional magnetic resonance imaging (fMRI) data analysis, statistical parametric mapping (SPM), is based on the general linear model (GLM). SPM therefore requires a priori knowledge or specific assumptions about the time courses contributing to signal changes. In contradistinction, independent component analysis (ICA) is a data-driven method based on the assumption that the causes of responses

Dewen Hu; Lirong Yan; Yadong Liu; Zongtan Zhou; Karl J. Friston; Changlian Tan; Daxing Wu

2005-01-01

237

Investigating emotion with music: An fMRI study  

Microsoft Academic Search

The present study used pleasant and unpleasant music to evoke emotion and functional magnetic resonance imaging (fMRI) to determine neural correlates of emotion processing. Unpleasant (permanently dissonant) music contrasted with pleasant (consonant) music showed activations of amyg- dala, hippocampus, parahippocampal gyrus, and temporal poles. These structures have previously been implicated in the emotional processing of stimuli with (negative) emotional valence;

Stefan Koelsch; Thomas Fritz; D. Yves v. Cramon; Karsten Müller; Angela D. Friederici

2006-01-01

238

Fully Bayesian spatio-temporal modeling of FMRI data  

Microsoft Academic Search

We present a fully Bayesian approach to modeling in functional magnetic resonance imaging (FMRI), incorporating spatio-temporal noise modeling and haemodynamic response function (HRF) modeling. A fully Bayesian approach allows for the uncertainties in the noise and signal modeling to be incorporated together to provide full posterior distributions of the HRF parameters. The noise modeling is achieved via a nonseparable space-time

Mark William Woolrich; Mark Jenkinson; J. Michael Brady; Stephen M. Smith

2004-01-01

239

The Diversity of Nuclear Magnetic Resonance Spectroscopy  

NASA Astrophysics Data System (ADS)

The discovery of the physical phenomenon of Nuclear Magnetic Resonance (NMR) in 1946 gave rise to the spectroscopic technique that has become a remarkably versatile research tool. One could oversimplify NMR spectros-copy by categorizing it into the two broad applications of structure elucidation of molecules (associated with chemistry and biology) and imaging (associated with medicine). But, this certainly does not do NMR spectroscopy justice in demonstrating its general acceptance and utilization across the sciences. This manuscript is not an effort to present an exhaustive, or even partial review of NMR spectroscopy applications, but rather to provide a glimpse at the wide-ranging uses of NMR spectroscopy found within the confines of a single magnetic resonance research facility, the Stanford Magnetic Resonance Laboratory. Included here are summaries of projects involving protein structure determination, mapping of intermolecular interactions, exploring fundamental biological mechanisms, following compound cycling in the environmental, analysis of synthetic solid compounds, and microimaging of a model organism.

Liu, Corey W.; Alekseyev, Viktor Y.; Allwardt, Jeffrey R.; Bankovich, Alexander J.; Cade-Menun, Barbara J.; Davis, Ronald W.; Du, Lin-Shu; Garcia, K. Christopher; Herschlag, Daniel; Khosla, Chaitan; Kraut, Daniel A.; Li, Qing; Null, Brian; Puglisi, Joseph D.; Sigala, Paul A.; Stebbins, Jonathan F.; Varani, Luca

240

Euclidean resonance in a magnetic field  

NASA Astrophysics Data System (ADS)

An analogy is found between Wigner resonant tunneling and tunneling across a static potential barrier in a static magnetic field. Whereas in the process of Wigner tunneling an electron encounters a classically allowed region where a discrete energy level coincides with its energy, in the magnetic field the potential barrier is constant in the direction of tunneling. Along the tunneling path, certain regions are formed where, in the classical language, the kinetic energy of the motion perpendicular to tunneling is negative. These regions play the role of potential wells, where a discrete energy level can coincide with the electron energy. This phenomenon, which occurs at a certain magnetic field, is called Euclidean resonance and substantially depends on the shape of the potential forces in the direction perpendicular to tunneling. Under conditions of Euclidean resonance, a long-distance underbarrier motion is possible, which can be observed in experiments.

Ivlev, B.

2007-08-01

241

Focal renal masses: magnetic resonance imaging  

SciTech Connect

Thirty patients with focal renal masses were evaluated on a .12-Tesla resistive magnetic resonance unit using partial saturation and spin echo pulse sequence. Fifteen patients had cystic lesions, nine patients had renal cell carcinoma, two had metastatic lesions, one had an angiomyolipoma, and three had focal bacterial infection. Renal cell carcinomas demonstrated areas of increased signal using a partial saturation sequence. Magnetic resonance imaging accurately detected perinephric extension and vascular invasion in all patients. Metastatic disease to the kidney was uniformly low in signal, in contrast to primary renal cell carcinoma; an angiomyolipoma demonstrated very high signal intensity. Two masses resulting from acute focal bacterial nephritis were uniformly low in signal. Magnetic resonance imaging appears to be an accurate way of detecting, identifying, and staging focal renal masses.

Choyke, P.L.; Kressel, H.Y.; Pollack, H.M.; Arger, P.M.; Axel, L.; Mamourian, A.C.

1984-08-01

242

Physiological noise in brainstem FMRI.  

PubMed

The brainstem is directly involved in controlling blood pressure, respiration, sleep/wake cycles, pain modulation, motor, and cardiac output. As such it is of significant basic science and clinical interest. However, the brainstem's location close to major arteries and adjacent pulsatile cerebrospinal fluid filled spaces, means that it is difficult to reliably record functional magnetic resonance imaging (fMRI) data from. These physiological sources of noise generate time varying signals in fMRI data, which if left uncorrected can obscure signals of interest. In this Methods Article we will provide a practical introduction to the techniques used to correct for the presence of physiological noise in time series fMRI data. Techniques based on independent measurement of the cardiac and respiratory cycles, such as retrospective image correction (RETROICOR, Glover et al., 2000), will be described and their application and limitations discussed. The impact of a physiological noise model, implemented in the framework of the general linear model, on resting fMRI data acquired at 3 and 7?T is presented. Data driven approaches based such as independent component analysis (ICA) are described. MR acquisition strategies that attempt to either minimize the influence of physiological fluctuations on recorded fMRI data, or provide additional information to correct for their presence, will be mentioned. General advice on modeling noise sources, and its effect on statistical inference via loss of degrees of freedom, and non-orthogonality of regressors, is given. Lastly, different strategies for assessing the benefit of different approaches to physiological noise modeling are presented. PMID:24109446

Brooks, Jonathan C W; Faull, Olivia K; Pattinson, Kyle T S; Jenkinson, Mark

2013-10-04

243

Neural Correlates of Feigned Memory Impairment are Distinguishable from Answering Randomly and Answering Incorrectly: An fMRI and Behavioral Study  

ERIC Educational Resources Information Center

|Previous functional magnetic resonance imaging (fMRI) studies have identified activation in the prefrontal-parietal-sub-cortical circuit during feigned memory impairment when comparing with truthful telling. Here, we used fMRI to determine whether neural activity can differentiate between answering correctly, answering randomly, answering…

Liang, Chun-Yu; Xu, Zhi-Yuan; Mei, Wei; Wang, Li-Li; Xue, Li; Lu, De Jian; Zhao, Hu

2012-01-01

244

Neural Correlates of Feigned Memory Impairment are Distinguishable from Answering Randomly and Answering Incorrectly: An fMRI and Behavioral Study  

ERIC Educational Resources Information Center

Previous functional magnetic resonance imaging (fMRI) studies have identified activation in the prefrontal-parietal-sub-cortical circuit during feigned memory impairment when comparing with truthful telling. Here, we used fMRI to determine whether neural activity can differentiate between answering correctly, answering randomly, answering…

Liang, Chun-Yu; Xu, Zhi-Yuan; Mei, Wei; Wang, Li-Li; Xue, Li; Lu, De Jian; Zhao, Hu

2012-01-01

245

Magnetic Microparticle Aggregation For Viscosity Determination By Magnetic Resonance  

PubMed Central

Micron-sized magnetic particles were induced to aggregate when placed in homogeneous magnetic fields, like those of magnetic resonance (MR) imagers and relaxometers, and then spontaneously returned to their dispersed state when removed from the field. Associated with the aggregation and dispersion of the magnetic particles were time dependent increases and decreases in the spin-spin relaxation time (T2) of the water. Magnetic nanoparticles, with far smaller magnetic moments per particle, did not undergo magnetically induced aggregation, and exhibited time independent values of T2. The rate of T2 change associated with magnetic micro-particle aggregation was used to determine the viscosity of liquid samples, providing a method that can be of particular advantage for determining the viscosity of small volumes of potentially biohazardous samples of blood or blood plasma.

Hong, Rui; Cima, Michael J.; Weissleder, Ralph; Josephson, Lee

2009-01-01

246

Granular convection observed by magnetic resonance imaging  

NASA Astrophysics Data System (ADS)

Vibrations in a granular material can spontaneously produce convection rolls reminiscent of those seen in fluids. Magnetic resonance imaging provides a sensitive and noninvasive probe for the detection of these convection currents, which have otherwise been difficult to observe. A magnetic resonance imaging study of convection in a column of poppy seeds yielded data about the detailed shape of the convection rolls and the depth dependence of the convection velocity. The velocity was found to decrease exponentially with depth; a simple model for this behavior is presented here.

Ehrichs, E. E.; Jaeger, H. M.; Karczmar, Greg S.; Knight, James B.; Kuperman, Vadim Yu.; Nagel, Sidney R.

1995-03-01

247

Magnetic resonance imaging of shoulder arthropathies.  

PubMed

The role of magnetic resonance imaging in evaluating shoulder arthropathies is evolving. This article reviews 4 of the major arthropathies: septic arthritis, rheumatoid arthritis, calcium pyrophosphate dihydrate (CPPD) deposition disease, and hydroxyapatite disease (HAD), with special attention to their magnetic resonance imaging features. Comfort with identifying these entities allows appropriate and prompt treatment, which is critical for joint preservation in the case of infection, for maximal therapeutic efficacy of disease-modifying drugs in the case of rheumatoid arthritis, and for expediting symptomatic relief in the cases of CPPD deposition disease and HAD. PMID:22469408

Sussmann, A Ross; Cohen, Jodi; Nomikos, George C; Schweitzer, Mark E

2012-02-16

248

Diffusion-weighted magnetic resonance imaging.  

PubMed

Diffusion-weighted magnetic resonance imaging is a specialized technique that measures the degree of diffusion of water molecules within extracellular space and between intracellular and extracellular space. Diffusion-weighted imaging signal is high (bright) when diffusion is restricted, as occurs in cytotoxic damage from ischemia, inflammation, trauma, or tumor. This technique, now available on most magnetic resonance imaging units, is especially helpful in detecting early ischemic stroke and multiple sclerosis and in differentiating arachnoid cyst from epidermoid tumor and brain abscess from neoplasm. PMID:12131474

Mukherji, Suresh K; Chenevert, Thomas L; Castillo, Mauricio

2002-06-01

249

Magnetic Resonance Imaging (MRI) Safety  

MedlinePLUS

... The powerful magnetic field aligns atomic particles called protons that are present in most of the body's tissues. The applied radio waves then cause these protons to produce signals that are picked up by ...

250

Advances in Magnetic Resonance Electrical Impedance Mammography  

NASA Astrophysics Data System (ADS)

Magnetic Resonance Electrical Impedance Mammography (MREIM) is a new imaging technique under development by Wollin Ventures, Inc. in conjunction with the H. Lee Moffitt Cancer Center & Research Institute. MREIM addresses the problem of low specificity of magnetic resonance mammography and high false-positive rates, which lead to unnecessary biopsies. Because cancerous tissue has a higher electrical conductivity than benign tissue, it may serve as a biomarker for differentiation between malignant and benign lesions. The MREIM principle is based on measuring both magnetic resonance and electric properties of the breast by adding a quasi-steady-state electric field to the standard magnetic resonance breast image acquisition. This applied electric field produces a current density that creates an additional magnetic field that in turn alters the native magnetic resonance signal in areas of higher electrical conductivity, corresponding to cancerous tissue. This work comprises MREIM theory, computer simulations, and experimental developments. First, a general overview and background review of tissue modeling and electrical-impedance imaging techniques are presented. The experimental part of this work provides a description of the MREIM apparatus and the imaging results of a custom-made breast phantom. This phantom was designed and developed to mimic the magnetic resonance and electrical properties of the breast. The theoretical part of this work provides an extension to the initial MREIM theoretical developments to further understand the MREIM effects. MREIM computer simulations were developed for both idealized and realistic tumor models. A method of numerical calculation of electric potential and induced magnetic field distribution in objects with irregular boundaries and anisotropic conductivity was developed based on the Finite Difference Method. Experimental findings were replicated with simulations. MREIM effects were analyzed with contrast diagrams to show the theoretical perceptibility as a function of the acquisition parameters. An important goal was to reduce the applied current. A new protocol for an MREIM sequence is suggested. This protocol defines parameters for the applied current synchronized to a specific magnetic resonance imaging sequence. A simulation utilizing this protocol showed that the MREIM effect is detectable for a 3-mm-diameter tumor with a current density of 0.5 A/m2, which is within acceptable limits.

Kovalchuk, Nataliya

251

Superconducting microwave resonators in magnetic fields  

NASA Astrophysics Data System (ADS)

Microwave resonators with high quality factors have enabled many recent breakthroughs with superconducting qubits and photon detectors. Vortices trapped in a superconducting resonator due to insufficient shielding or pulsed control fields constitute one potential loss mechanism that can lead to reduced quality factors. We have developed a straightforward method for enhancing the pinning, and thus reducing the excess loss from vortices trapped by field-cooling by over an order of magnitude, in Al resonators using nanofabricated surface pinning. We have also studied resonators in the absence of field-cooling, where magnetic fields applied below the transition temperature of the superconductor can still influence the behavior, by producing reversible shifts in the resonance frequency for small fields and by injecting vortices into the films at larger fields.

Song, C.; Defeo, M. P.; Yu, K.; Xiao, B.; Bhupathi, P.; Plourde, B. L. T.

2010-03-01

252

The fMRI signal, slow cortical potential and consciousness  

PubMed Central

As functional magnetic resonance imaging (fMRI) has become a driving force in cognitive neuroscience, it is crucial to understand the neural basis of the fMRI signal. Here, we discuss a novel neurophysiological correlate of the fMRI signal, the slow cortical potential (SCP), which also seems to modulate the power of higher-frequency activity, the more established neurophysiological correlate of the fMRI signal. We further propose a hypothesis for the involvement of the SCP in the emergence of consciousness, and review existing data that lend support to our proposal. This hypothesis, unlike several previous theories of consciousness, is firmly rooted in physiology and as such is entirely amenable to empirical testing.

He, Biyu J.; Raichle, Marcus E.

2010-01-01

253

Video: Proton Nuclear Magnetic Resonance (NMR)  

NSDL National Science Digital Library

This video, distributed on YouTube by the Royal Society of Chemistry, describes the basic principles of Nuclear Magnetic Resonance. This video is a good primer and would be very useful to supplement introductory lectures on NMR. The video covers the basic theory behind a 1H spectrum and goes through actually acquiring a spectrum. The top-off look of the instrument is useful and how the superconducting magnet is mounted. Running time for the video is 8:43.

2011-06-03

254

Tumor Detection by Nuclear Magnetic Resonance  

Microsoft Academic Search

Spin echo nuclear magnetic resonance measurements may be used as a method for discriminating between malignant tumors and normal tissue. Measurements of spin-lattice (T1) and spin-spin (T2) magnetic relaxation times were made in six normal tissues in the rat (muscle, kidney, stomach, intestine, brain, and liver) and in two malignant solid tumors, Walker sarcoma and Novikoff hepatoma. Relaxation times for

Raymond Damadian

1971-01-01

255

Magnetic resonance of ferrite nanoparticles  

Microsoft Academic Search

Ferromagnetic resonance (FMR) experiments at 9.26GHz on non-interacting maghemite (?-Fe2O3) nanoparticles of ferrofluids are performed as a function of temperature (3.5–300K) and particle diameter (4.8–10nm). The orientational mobility of the particles inside the fluid is employed to monitor the orientational distribution of the anisotropy axes by solidifying the MF matrix under the external field. On those textured suspensions, angular analysis

F. Gazeau; J. C Bacri; F. Gendron; R. Perzynski; Yu. L Raikher; V. I. Stepanov; E. Dubois

1998-01-01

256

Localized ferromagnetic resonance using Magnetic Resonance Force Microscopy  

NASA Astrophysics Data System (ADS)

Magnetic Resonance Force Microscopy (MRFM) is a novel approach to scanned probe imaging, combining the advantages of Magnetic Resonance Imaging (MRI) with Scanning Probe Microscopy (SPM) [1]. It has extremely high sensitivity that has demonstrated detection of individual electron spins [2] and small numbers of nuclear spins [3]. Here we describe our MRFM experiments on Ferromagnetic thin film structures. Unlike ESR and NMR, Ferromagnetic Resonance (FMR) is defined not only by local probe field and the sample structures, but also by strong spin-spin dipole and exchange interactions in the sample. Thus, imaging and spatially localized study using FMR requires an entirely new approach. In MRFM, a probe magnet is used to detect the force response from the sample magnetization and it provides local magnetic field gradient that enables mapping of spatial location into resonance field. The probe field influences on the FMR modes in a sample, thus enabling local measurements of properties of ferromagnets. When sufficiently intense, the inhomogeneous probe field defines the region in which FMR modes are stable, thus producing localized modes. This feature enables FMRFM to be important tool for the local study of continuous ferromagnetic samples and structures. In our experiments, we explore the properties of the FMR signal as the strength of the local probe field evolves from the weak to strong perturbation limit. This underlies the important new capability of Ferromagnetic resonance imaging, a powerful new approach to imaging ferromagnet. The new developed FMR imaging technique enables FMR imaging and localized FMR spectroscopy to combine spectroscopy and lateral information of ferromagnetic resonance images [4][5]. Our theoretical approach agrees well with spatially localized spectroscopy and imaging results. This approach also allows analysis and reconstruction of FMR modes in a sample. Finally we consider the effect of strong probe fields on FMR modes. In this regime the probe field significantly modifies the FMR modes. In particular we observe the complete local suppression of the FMR mode under the probe. This provides as a new tool for local study of continuous ferromagnetic thin films and microstructures.

Kim, Jongjoo

257

Off-center magnetic resonance imaging with permanent magnets  

NASA Astrophysics Data System (ADS)

Magnets for magnetic resonance imaging are currently designed as structures that are symmetric with respect to the geometric center O of the magnet cavity. This symmetry results in a symmetric field configuration, where point O coincides with the imaging center S defined as the point where the field gradient is zero. However, in many clinical applications such as breast or spine imaging, the region of interest is displaced from the geometric center. We present a design method for yokeless permanent magnets, where the position of point S is dictated by the imaging requirements. The magnet is composed of uniformly magnetized triangular prisms and it does not require a ferromagnetic yoke to channel the magnetic flux. Given an arbitrary polygonal cavity, the design depends on the position of point F, where the magnetostatic potential is assumed to be equal to the magnetostatic potential of the external medium. For a long magnet, the position of the imaging center S coincides with point F. As an example of the off-center design, we analyze a three-dimensional yokeless magnet with cavity of width=length=80 cm and height=45 cm. The magnet generates a field above 0.5 T when constructed using the NdFeB alloy of remanence larger than 1.3 T. The off-center configuration offers flexibility in magnet design that makes it possible to focus on a particular region of the human body, without increasing magnet cavity, magnet size, or its weight

Abele, Manlio G.; Rusinek, Henry

2008-04-01

258

Magnetic Resonance Imaging (MRI): Brain  

MedlinePLUS

... test that uses a magnetic field and radio waves to produce detailed images of the brain and the brain stem. An MRI differs from ... hospitals and radiology centers. During the exam, radio waves manipulate ... pinpoint problems in the brain and the brain stem when the scan focuses ...

259

Magnetic resonance investigation of magnetic-labeled baker's yeast cells  

NASA Astrophysics Data System (ADS)

In this study, the interaction of DMSA-coated magnetite nanoparticles (5 and 10nm core-size) with Saccharomyces cerevisae was investigated using magnetic resonance (MR) and transmission electron microscopy (TEM). The TEM micrographs revealed magnetite nanoparticles attached externally to the cell wall. The MR data support the strong interaction among the nanoparticles supported by the cells. A remarkable shift in the resonance field was used as signature of particle attachment to the cell wall.

Godoy Morais, J. P. M.; Azevedo, R. B.; Silva, L. P.; Lacava, Z. G. M.; Báo, S. N.; Silva, O.; Pelegrini, F.; Gansau, C.; Buske, N.; Safarik, I.; Safarikova, M.; Morais, P. C.

2004-05-01

260

Imaging Intelligence with Proton Magnetic Resonance Spectroscopy  

ERIC Educational Resources Information Center

|Proton magnetic resonance spectroscopy ([to the first power]H-MRS) is a technique for the assay of brain neurochemistry "in vivo." N-acetylaspartate (NAA), the most prominent metabolite visible within the [to the first power]H-MRS spectrum, is found primarily within neurons. The current study was designed to further elucidate NAA-cognition…

Jung, Rex E.; Gasparovic, Charles; Chavez, Robert S.; Caprihan, Arvind; Barrow, Ranee; Yeo, Ronald A.

2009-01-01

261

Magnetic resonance imaging in patients with panhypopituitarism  

Microsoft Academic Search

Primary panhypopituitarism consists of functional deficiency of the anterior pituitary lobe, which appears during infancy or adolescence. The magnetic resonance findings in 10 patients with a history of primary hopopituitarism are presented. The findings include: reduced pituitary size in all cases: partially (8 cases) or totally (2 cases) empty sella; thin (4 cases), partially visible (3 cases) or absent (2

R. S. Pozzi Mucelli; F. Frezza; S. Magnaldi; G. Proto

1992-01-01

262

Respiratory gating of magnetic resonance images  

Microsoft Academic Search

When compared to most other high resolution imaging modalities (i.e. CT), magnetic resonance (MR) requires significantly more time for data acquisition. The average MR scan time ranges from 2 to 6 minutes. Cardiac and respiratory motion cause large artifacts and significantly reduce the resolution of internal structures. Thus, a method for gating MR acquisition with the respiratory cycle was developed.

J. A. Clanton; V. M. Runge; A. E. Jr. James

1984-01-01

263

Magnetic resonance imaging of the elbow  

Microsoft Academic Search

Magnetic resonance imaging (MRI) provides useful information regarding the elbow joint. Many abnormalities seen in the elbow are a result of trauma, often from sports such as baseball and tennis. Elbow problems are frequently related to the medial tension-lateral compression phenomenon where repeated valgus stress produces flexor-pronator strain, ulnar collateral ligament sprain, ulnar traction spurring, and ulnar neuropathy. The lateral

Lynne S. Steinbach; Russell C. Fritz; Phillip F. J. Tirman; Martin Uffman

1997-01-01

264

Analytical Methods for Characterizing Magnetic Resonance Probes  

PubMed Central

SUMMARY The efficiency of Gd(III) contrast agents in magnetic resonance image enhancement is governed by a set of tunable structural parameters. Understanding and measuring these parameters requires specific analytical techniques. This Feature describes strategies to optimize each of the critical Gd(III) relaxation parameters for molecular imaging applications and the methods employed for their evaluation.

Manus, Lisa M.; Strauch, Renee C.; Hung, Andy H.; Eckermann, Amanda L.; Meade, Thomas J.

2012-01-01

265

Resonant mechanical magnetic sensor in standard CMOS  

Microsoft Academic Search

A novel micromechanical magnetic sensor has been built and tested. The field is detected by measuring the vibration amplitude of a mechanical Lorentz force oscillator. This device is made from a standard 2-?m CMOS fabrication process with a post-processing etch step to undercut and release the sensor. When operated at the resonant frequency of the mechanical system, a sensitivity of

Beverley Eyre; Kristofer S. J. Pister; William Kaiser

1998-01-01

266

Magnetic resonance imaging in obstructive Müllerian anomalies.  

PubMed

Herlyn-Werner-Wunderlich (HWW) syndrome is a very rare congenital anomaly of the urogenital tract involving Müllerian ducts and Wolffian structures. It is characterized by the triad of didelphys uterus, obstructed hemivagina, and ipsilateral renal agenesis. Magnetic resonance imaging (MRI) is a sensitive, non-invasive diagnostic modality for demonstrating anatomic variation and associated complications. PMID:24082660

Sen, Kamal Kumar; Balasubramaniam, Dhivya; Kanagaraj, Vikrant

2013-04-01

267

Nuclear Magnetic Resonance Technology for Medical Studies.  

ERIC Educational Resources Information Center

|Reports on the status of nuclear magnetic resonance (NMR) from theoretical and clinical perspectives, reviewing NMR theory and relaxation parameters relevant to NMR imaging. Also reviews literature related to modern imaging strategies, signal-to-noise ratio, contrast agents, in vivo spectroscopy, spectroscopic imaging, clinical applications, and…

Budinger, Thomas F.; Lauterbur, Paul C.

1984-01-01

268

Magnetic resonance imaging in motor neuron disease  

Microsoft Academic Search

Magnetic resonance imaging (MRI) of the brain was evaluated in 20 patients with motor neuron disease (MND) and in a control group of 11 healthy people. Bilateral increased signal areas of various sizes in the centrum semiovale, corona radiata, internal capsule, pedunculi of midbrain, pons, medulla and even in the frontal lobe, topographically related with the corticospinal tract, were found

M. L. Sales Luís; A. Hormigo; C. Maurício; M. M. Alves; R. Serrão

1990-01-01

269

Intraoperative Magnetic Resonance Imaging Safety Considerations  

Microsoft Academic Search

Patient safety considerations are a priority for perioperative nurses. In the intraoperative magnetic resonance imaging (MRI) chamber, additional safety precautions for both patients and staff members must be taken. This article provides a brief overview of the intraoperative MRI environment and details safety considerations for surgical staff members and patients. AORN J 77 (March 2003) 590–592.

Lori Russell

2003-01-01

270

Sample spinner for nuclear magnetic resonance spectrometer  

SciTech Connect

A sample spinner for a nuclear magnetic resonance spectrometer having improved operating characteristics is described comprising a rotor supported at both ends by support gas bearings and positioned by a thrust gas bearing. Improved support gas bearings are also described which result in a spinner exhibiting long-term stable operation characteristics.

Stejskal, E.O.

1984-05-01

271

Magnetic Resonance Imaging in Biomedical Engineering  

NASA Astrophysics Data System (ADS)

The basic principles of magnetic resonance imaging covering physical principles and basic imaging techniques will be presented as a strong tool in biomedical engineering. Several applications of MRI in biomedical research practiced at the MRI laboratory of the FBMI CTU including other laboratory instruments and activities are introduced.

Ka?par, Jan; Hána, Karel; Smr?ka, Pavel; Brada, Ji?í; Beneš, Ji?í; Šunka, Pavel

2007-11-01

272

Nuclear magnetic resonance in rare earth metals  

Microsoft Academic Search

This article describes the study, by nuclear magnetic resonance, of both static and dynamical aspects of the hyperfine interaction in rare earth metals, and illustrates the categories of information that can be obtained by using nuclei as microscopic probes in metallic media. The systems discussed include not only the pure rare earth metals but also their alloys and their metallic

M. A. H. McCausland; I. S. Mackenzie

1979-01-01

273

Small Animal Imaging with Magnetic Resonance Microscopy  

Microsoft Academic Search

Small animal magnetic resonance microscopy (MRM) has evolved significantly from testing the boundaries of imag- ing physics to its expanding use today as a tool in nonin- vasive biomedical investigations. MRM now increasingly provides functional information about living animals, with images of the beating heart, breathing lung, and functioning brain. Unlike clinical MRI, where the focus is on diagnosis, MRM

Bastiaan Driehuys; John Nouls; Alexandra Badea; Elizabeth Bucholz; Ketan Ghaghada; Alexandra Petiet; Laurence W. Hedlund

2008-01-01

274

Magnetic resonance studies of dissolving particulate solids  

Microsoft Academic Search

Magnetic resonance methods have been used to elucidate the internal pore structure of particulate solids, in particular detergent tablets. Such information is essential to a comprehensive understanding of the dissolution characteristics of these materials and how this property is related to processing conditions during tablet formation. In particular 3-D images of porosity are produced and 2-D self-diffusion maps are acquired

M. L. Johns; L. F. Gladden

2003-01-01

275

Coolant quality for magnetic resonance imaging systems  

Microsoft Academic Search

As radiologists demand increased power, speed and duty cycle from their magnetic resonance imaging (MRI) systems, thermal management of the gradient sub-system becomes more challenging. A heat exchanger in the MRI system cools heat-generating components by pumping water through hollow copper tubing, which also carries high electrical currents. Water is used as a coolant because of its high specific heat

Julie Wong; Garron K Morris

2008-01-01

276

Nuclear Magnetic Resonance Technology for Medical Studies  

Microsoft Academic Search

Nuclear magnetic resonance proton imaging provides anatomical definition of normal and abnormal tissues with a contrast and detection sensitivity superior to those of x-ray computed tomography in the human head and pelvis and parts of the cardiovascular and musculoskeletal systems. Recent improvements in technology should lead to advances in diagnostic imaging of the breast and regions of the abdomen. Selected-region

Thomas F. Budinger; Paul C. Lauterbur

1984-01-01

277

Nuclear magnetic resonance technology for medical studies  

Microsoft Academic Search

Nuclear magnetic resonance proton imaging provides anatomical definition of normal and abnormal tissues with a contrast and detection sensitivity superior to those of x-ray computed tomography in the human head and pelvis and parts of the cardiovascular and musculoskeletal systems. Recent improvements in technology should lead to advances in diagnostic imaging of the breast and regions of the abdomen. Selected-region

T. F. Budinger; P. C. Lauterbur

1984-01-01

278

Magnetic resonance imaging of pelvic organ prolapse  

Microsoft Academic Search

Magnetic resonance imaging (MRI) of pelvic organ prolapse is technically feasible and has several advantages when compared with fluoroscopic cystoproctography. Organ descent and the supportive structures of the pelvic floor can be assessed with MRI. The role of MRI in evaluating patients with pelvic floor dysfunction is evolving, and there have been many developments in the past few years. The

H. K. Pannu; Russell H. Morgan

2002-01-01

279

Advances in emission tomography and magnetic resonance  

Microsoft Academic Search

This paper will review recent technical improvements in emission tomography (PET and SPECT) as well as new approaches in magnetic resonance in vivo studies (MRI and MRS). These advances now enable more detailed studies of dementia and heart disease as well as improved methods to diagnose and treat cancer. Forms of dementia (Parkinson's and Alzheimer's disease) can now be quantitatively

T. F. Budinger

2008-01-01

280

Magnetic resonance imaging of painful shoulder arthroplasty  

Microsoft Academic Search

Specialized magnetic resonance imaging (MRI) was performed in 42 painful shoulder arthroplasties, 22 of which underwent subsequent revision surgery, allowing surgical confirmation of the pathology identified on MRI. One hemiarthroplasty was excluded because of motion artifact, leaving 21 studies (19 patients) to be correlated retrospectively to the surgical findings. At the time of revision surgery, there were full-thickness rotator cuff

John W Sperling; Hollis G Potter; Edward V Craig; Evan Flatow; Russell F Warren

2002-01-01

281

Nuclear magnetic resonance in plant science research  

Microsoft Academic Search

In vivo nuclear magnetic resonance (NMR) spectroscopy and NMR imaging are noninvasive techniques with the potential to investigate a wide range of biochemical and physiological problems in living systems. The extent to which this potential has been realized in plant tissues is discussed with reference to recent applications to a number of systems, including root tissues and plant cell suspensions.

R. G. Ratcliffe

1991-01-01

282

Magnetic Resonance Imaging Methods in Soil Science  

Microsoft Academic Search

Magnetic Resonance Imaging (MRI) is a powerful technique to study water content, dynamics and transport in natural porous media. However, MRI systems and protocols have been developed mainly for medical purposes, i.e. for media with comparably high water contents and long relaxation times. In contrast, natural porous media like soils and rocks are characterized by much lower water contents, typically

A. Pohlmeier; D. van Dusschoten; P. Blümler

2009-01-01

283

Texture analysis methodologies for magnetic resonance imaging  

PubMed Central

Methods for the analysis of digital-image texture are reviewed. The functions of MaZda, a computer program for quantitative texture analysis developed within the framework of the European COST (Cooperation in the Field of Scientific and Technical Research) B11 program, are introduced. Examples of texture analysis in magnetic resonance images are discussed.

Materka, Andrzej

2004-01-01

284

Sports health magnetic resonance imaging challenge.  

PubMed

Injuries to the Lisfranc ligament complex are often suspected, particularly in the setting of midfoot pain without radiographic abnormality. Knowledge of the anatomy and magnetic resonance imaging findings of injuries to this region is helpful for the diagnosing and treating physicians. PMID:23015984

Howell, Gary A; Stadnick, Michael E; Awh, Mark H

2010-11-01

285

Magnetic Resonance Imaging (MRI) of the Kidney.  

National Technical Information Service (NTIS)

The thesis reflects experience with Magnetic Resonance Imaging (MRI) in the diagnosis of kidney disease. Initial results were obtained on a 0.15 T resistive and a 0.5 T superconducting prototype MR scanner (Philips, Best, the Netherlands). Further clinica...

L. Te Strake

1987-01-01

286

Brain Morphometry Using Anatomical Magnetic Resonance Imaging  

ERIC Educational Resources Information Center

|The efficacy of anatomical magnetic resonance imaging (MRI) in studying the morphological features of various regions of the brain is described, also providing the steps used in the processing and studying of the images. The ability to correlate these features with several clinical and psychological measures can help in using anatomical MRI to…

Bansal, Ravi; Gerber, Andrew J.; Peterson, Bradley S.

2008-01-01

287

Atomic Resolution Magnetic Resonance Diffraction using Magnetic Probes  

NASA Astrophysics Data System (ADS)

We will present our recent proposal [1] for the observation of sharp spectral peaks in the magnetic resonance signal for the case of a crystal in close proximity of a ferromagnetic nanosphere. The appearance of the peaks is a direct signature of the discrete atomic sites in the crystal lattice, and the positions of the spectral peaks are sensitive to the crystal unit cell size thereby providing a magnetic resonance diffraction method for determination of the basic parameters of the crystal at the atomic scale. The technique relaxes the challenging requirements for single spin detection instrument proposals by allowing many spins to coherently contribute to the magnetic resonance signal while still revealing atomic resolution information. Therefore, the technique provides a magnetic resonance alternative to the other three well-known atomic resolution crystallography techniques of x-ray, electron, and neutron diffraction. Applications to the studies of crystals, thin films, and crystallites will be discussed, and potential measurement methods for the confirmation of the diffraction theory will be proposed [2]. The analysis suggests that the long desired goal of detecting atomic resolution magnetic resonance diffraction [3] is well within reach of current experimental techniques such as Magnetic Resonance Force Microscopy (MRFM) [4]. [1] M. Barbic J. Appl. Phys. vol. 91, p. 9987 (2002). [2] M. Barbic and A. Scherer J. Appl. Phys. vol. 92, p. 7345 (2002). [3] P. Mansfield and P. K. Grannell J. Phys. C: Solid State Phys. vol. 6, p. L422 (1973). [4] Sidles J. A. et al. Rev. Mod. Phys. vol. 67, p. 249 (1995).

Barbic, Mladen

2003-03-01

288

Computer-controlled stimulation for functional magnetic resonance imaging studies of the neonatal olfactory system  

PubMed Central

Aim Olfactory sensation is highly functional early in human neonatal life, with studies suggesting that odours can influence behaviour and infant–mother bonding. Due to its good spatial properties, blood oxygen level–dependent (BOLD) contrast functional magnetic resonance imaging (fMRI) has the potential to rapidly advance our understanding of the neural activity which underlies the development of olfactory perception in this key period. We aimed to design an ‘olfactometer’ specifically for use with neonatal subjects for fMRI studies of odour perception. Methods We describe a fully automated and programmable, fMRI compatible system capable of presenting odorant liquids. To prevent contamination of the system and minimize between-subject infective risk, the majority of the olfactometer is constructed from single-use, readily available clinical equipment. The system was used to present the odour of infant formula milk in a validation group of seven neonatal subjects at term equivalent postmenstrual age (median age 40 weeks). Results A safe, reliable and reproducible pattern of stimulation was delivered leading to well-localized positive BOLD functional responses in the piriform cortex, amygdala, thalamus, insular cortex and cerebellum. Conclusions The described system is therefore suitable for detailed studies of the ontology of olfactory sensation and perception during early human brain development.

Arichi, T; Gordon-Williams, R; Allievi, A; Groves, AM; Burdet, E; Edwards, AD

2013-01-01

289

21 CFR 892.1000 - Magnetic resonance diagnostic device.  

Code of Federal Regulations, 2010 CFR

...spatial distribution and/or magnetic resonance spectra which reflect frequency...of nuclei exhibiting nuclear magnetic resonance. Other physical parameters...includes hydrogen-1 (proton) imaging, sodium-23 imaging,...

2009-04-01

290

21 CFR 892.1000 - Magnetic resonance diagnostic device.  

Code of Federal Regulations, 2010 CFR

...spatial distribution and/or magnetic resonance spectra which reflect frequency...of nuclei exhibiting nuclear magnetic resonance. Other physical parameters...includes hydrogen-1 (proton) imaging, sodium-23 imaging,...

2010-04-01

291

Multivariate Strategies in Functional Magnetic Resonance Imaging  

ERIC Educational Resources Information Center

|We discuss aspects of multivariate fMRI modeling, including the statistical evaluation of multivariate models and means for dimensional reduction. In a case study we analyze linear and non-linear dimensional reduction tools in the context of a "mind reading" predictive multivariate fMRI model.|

Hansen, Lars Kai

2007-01-01

292

The market for magnetic resonance spectroscopy  

SciTech Connect

The medical market is, at present, the most dominant market for low T{sub c} superconductors. Indeed, without magnetic resonance imaging (MRI), there would hardly be a low T{sub c} superconductor market at all. According to the author, any development that can expand the medical market for MRI machines would be a welcome one. This paper reports how the recent advances in magnetic resonance spectroscopy (MRS) are such a development. While the principle of MRS has bee around as long as MRI, only recently have advances in technique, computer programming and magnet technology allowed MRS to advance to a point where it may become an important technology-one that could increase the medical market for superconductors. The author discussed how MRS can be used to analyze oil core samples for their oil content, oil/water ratios, how the oil is bound and how to extract it.

Carlson, L.

1990-01-01

293

Geometric Optimization and Microstructuring of Magnetic Concentrators for a Resonant Magnetic Sensor  

Microsoft Academic Search

This paper reports the design and analysis of a planar magnetic field concentrator with two gaps used for a resonant magnetic sensor and technology steps towards its realization. The device is based on a previously published resonant magnetic sensor combining a magnetic field concentrator and a mechanical resonator. A physical model is reported to explain the magnetic forces acting between

S. Brugger; O. Paul

2007-01-01

294

Analysis of fMRI data by blind separation into independent spatial components  

Microsoft Academic Search

r r Abstract: Current analytical techniques applied to functional magnetic resonance imaging (fMRI) data require a priori knowledge or specific assumptions about the time courses of processes contributing to the measured signals. Here we describe a new method for analyzing fMRI data based on the independent component analysis (ICA) algorithm of Bell and Sejnowski ((1995): Neural Comput 7:1129-1159). We decomposed

Martin J. Mckeown; Scott Makeig; Greg G. Brown; Sandra S. Kindermann; Anthony J. Bell; Terrence J. Sejnowski

1998-01-01

295

Imaging Cognition II: An Empirical Review of 275 PET and fMRI Studies  

Microsoft Academic Search

Positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) have been extensively used to explore the functional neuroanatomy of cognitive functions. Here we review 275 PET and fMRI studies of attention (sustained, selective, Stroop, orientation, divided), perception (object, face, space\\/motion, smell), imagery (object, space\\/ motion), language (written\\/spoken word recognition, spoken\\/ no spoken response), working memory (verbal\\/numeric, object, spatial, problem

Roberto Cabeza; Lars Nyberg

2000-01-01

296

FMRI group studies of brain connectivity via a group robust Lasso  

Microsoft Academic Search

Inferring effective brain connectivity from neuroimaging data such as functional Magnetic Resonance Imaging (fMRI) has been attracting increasing interest due to its critical role in understanding brain functioning. Incorporating sparsity into connectivity modeling to make models more biologically realistic and performing group analysis to deal with inter-subject variability are still challenges associated with fMRI brain connectivity modeling. To address the

Xiaohui Chen; Z. Jane Wang; Martin J. McKeown

2010-01-01

297

The Range of Motor Activation in the Normal Human Cortex Using Bold fMRI  

Microsoft Academic Search

Summary  Understanding and documenting the nature of normal human brain functional motor activation using functional Magnetic Resonance Imaging (fMRI) is necessary, if valid statements are to be made about normal and disease functional states using fMRI activation maps. The present study examines activation maps in ’normal‘ adults. Six healthy adult volunteers performed three motor tasks isolating the tongue, non-dominant foot, and

Diana J. Vincent; Courtnay J. Bloomer; Vanessa K. Hinson; Kenneth J. Bergmann

2006-01-01

298

fMRI of severe to profoundly hearing-impaired infants and toddlers under sedation  

Microsoft Academic Search

Functional Magnetic Resonance (fMRI) can be used to visualize activation of the central auditory system in hearing-impaired (HI) children. fMRI is normally done by comparing images in a resting state with images of the brain acquired in a stimulated state. We use two stimulation tasks: auditory stimulation with tones and language stimulation with sentences read in a female voice. Results

S. K. Holland; D. I. Choo; J. K. Ret; L. Hilbert; R. S. Dunn; V. J. Schmithorst

2004-01-01

299

Assessment of Hemispheric Language Lateralization: A Comparison Between fMRI and fTCD  

Microsoft Academic Search

The cerebral blood flow velocity (CBFV) in the basal arteries during a word-generation task was assessed by functional transcranial Doppler ultrasonography (fTCD) and by functional magnetic resonance imaging (fMRI). The study investigates how event-related CBFV modulations in the middle cerebral artery (MCA) relate to regional cerebral blood flow (rCBF) changes. Both fMRI and fTCD were used in 13 subjects (7

Michael Deppe; Stefan Knecht; Karsten Papke; Hubertus Lohmann; Helge Fleischer; Walter Heindel; E. Bernd Ringelstein; Henning Henningsen

2000-01-01

300

fMRI Data Analysis With Nonstationary Noise Models: A Bayesian Approach  

Microsoft Academic Search

The assumption of noise stationarity in the functional magnetic resonance imaging (fMRI) data analysis may lead to the loss of crucial dynamic features of the data and thus result in inaccurate activation detection. In this paper, a Bayesian approach is proposed to analyze the fMRI data with two nonstationary noise models (the time-varying variance noise model and the fractional noise

Huaien Luo; Sadasivan Puthusserypady

2007-01-01

301

Order Selection of the Linear Mixing Model for Complex-Valued FMRI Data  

Microsoft Academic Search

Functional magnetic resonance imaging (fMRI) data are originally acquired as complex-valued images, which motivates the use\\u000a of complex-valued data analysis methods. Due to the high dimension and high noise level of fMRI data, order selection and\\u000a dimension reduction are important procedures for multivariate analysis methods such as independent component analysis (ICA).\\u000a In this work, we develop a complex-valued order selection

Wei Xiong; Yi-Ou Li; Nicolle Correa; Xi-Lin Li; Vince D. Calhoun; Tülay Adal?

302

Global and local fMRI signals driven by neurons defined optogenetically by type and wiring  

Microsoft Academic Search

Despite a rapidly-growing scientific and clinical brain imaging literature based on functional magnetic resonance imaging (fMRI) using blood oxygenation level-dependent (BOLD) signals, it remains controversial whether BOLD signals in a particular region can be caused by activation of local excitatory neurons. This difficult question is central to the interpretation and utility of BOLD, with major significance for fMRI studies in

Jin Hyung Lee; Remy Durand; Viviana Gradinaru; Feng Zhang; Inbal Goshen; Dae-Shik Kim; Lief E. Fenno; Charu Ramakrishnan; Karl Deisseroth

2010-01-01

303

Puzzlingly High Correlations in fMRI Studies of Emotion, Personality, and Social  

Microsoft Academic Search

ABSTRACT—Functional magnetic resonance imaging (fMRI) studies of emotion, personality, and social cognition have drawn much attention in recent years, with high-profile studies frequently reporting extremely high (e.g., >.8) cor- relationsbetweenbrainactivationandpersonalitymeasures. We show that these correlations are higher than should be expected given the (evidently limited) reliability of both fMRI and personality measures. The high correlations are all the more puzzling

Edward Vul; Christine Harris; Piotr Winkielman; Harold Pashler

2009-01-01

304

Development of a FMRI simulator for modelling realistic rigid-body motion artifacts  

Microsoft Academic Search

Functional Magnetic Resonance Imaging (FMRI) is a non-invasive method of imaging brain function in-vivo. However, images produced in FMRI exper- iments are imperfect and contain several artifacts which contaminate the data. These artifacts include rigid-body motion effects, B0-field inhomogeneities, chemical shift and eddy currents. To investigate these artifacts, with the eventual aim of minimising or re- moving them completely, a

Ivana Drobnjak; David Gavaghan; Joe Pitt-Francis

305

Multi-voxel Non-linear fMRI Analysis: A Grid Computing Approach  

Microsoft Academic Search

Functional magnetic resonance imaging (fMRI) is a medical imaging technique used to characterize brain physiological activity, usually presented as 3D volumes in function of time. Our previous work in nonlinear association studies in electroencephalogram (EEG) time series enabled us to identify EEG features relevant for clinical diagnosis. The use of a similar approach in fMRI (adapted for 3D time series)

José Maria

306

Motion correction in fMRI via registration of individual slices into an anatomical volume  

Microsoft Academic Search

An automated retrospective image registration based on mutual information is adapted to a multislice functional magnetic resonance imaging (fMRI) acquisition protocol to provide accu- rate motion correction. Motion correction is performed by mapping each slice to an anatomic volume data set acquired in the same fMRI session to accommodate inter-slice head motion. Accuracy of the registration parameters was assessed by

Boklye Kim; Jennifer L. Boes; Peyton H. Bland; Thomas L. Chenevert; Charles R. Meyer

1999-01-01

307

Application of MultiScale Hidden Markov Modeling Wavelet Coefficients to fMRI Activation Detection  

Microsoft Academic Search

Problem Statement: The problem of detection of functional magnetic resonance images (fMRIs), that is, to decide active and nonactive regions of human brain from fMRIs is studied in this paper. fMRI research is finding and will find more and more applications in diagnosing and treating brain diseases like depression and schizophrenia. At its initial stage fMRI detection are pixel-wise methods,

Fangyuan Nan; Yaonan Wang; Xiaoping Ma

2008-01-01

308

Spatiotemporal Frequency and Direction Sensitivities of Human Visual Areas Measured Using fMRI  

Microsoft Academic Search

Using functional magnetic resonance imaging (fMRI) we have studied the variation in response magnitude, in each visual area (V1–V5), as a function of spatial frequency (SF), temporal frequency (TF) and unidirectional motion versus counterphase flicker. Each visual area was identified in each subject using a combination of retinotopic mapping fMRI and cortical flattening techniques. A drifting (or counterphasing) sinusoidal grating

K. D. Singh; A. T. Smith; M. W. Greenlee

2000-01-01

309

Functional phantom for fMRI: a feasibility study.  

PubMed

Functional magnetic resonance imaging (fMRI) reveals changes in blood oxygen level-dependent (BOLD) signal after considerable processing. This paper describes the implementation and testing of an fMRI phantom where electric current applied to a thin wire within a proton-rich medium substituted BOLD distortion of the magnetic field; the scanner detects these two distortions as practically identical signal changes. The magnitude of the change depended on the current strength. The phantom has a number of possible applications. Signal changes across sessions, days, instruments and individuals could be monitored. Placing the phantom close to a subject during an fMRI experiment could allow differentiating sensitivity changes in the scanner due to instrumentation from changes in the subject's state and performance during the experiment. The spatial extent of brain activations and effects of various changes in the chain of image formation could be analyzed using current-induced "activations". Furthermore, the phantom could expedite fMRI sequence development by reducing the need to scan human subjects, who introduce uncertainty to the signal. Thus, this fMRI phantom could be useful for both cognitive fMRI studies and scanner calibration. PMID:16563961

Renvall, Ville; Joensuu, Raimo; Hari, Riitta

2006-02-20

310

Two different reorganization patterns after rehabilitative therapy: An exploratory study with fMRI and TMS  

Microsoft Academic Search

We used two complementary methods to investigate cortical reorganization in chronic stroke patients during treatment with a defined motor rehabilitation program. BOLD (“blood oxygenation level dependent”) sensitive functional magnetic resonance imaging (fMRI) and intracortical inhibition (ICI) and facilitation (ICF) measured with transcranial magnetic stimulation (TMS) via paired pulse stimulation were used to investigate cortical reorganization before and after “constraint-induced movement

Farsin Hamzei; Joachim Liepert; Christian Dettmers; Cornelius Weiller; Michel Rijntjes

2006-01-01

311

Magnetic resonance of calcified tissues.  

PubMed

MRI of the human body is largely made possible by the favorable relaxation properties of protons of water and triacyl glycerides prevalent in soft tissues. Hard tissues--key among them bone--are generally less amenable to measurement with in vivo MR imaging techniques, not so much as a result of the lower proton density but rather due to the extremely short life-times of the proton signal in water bound to solid-like entities, typically collagen, or being trapped in micro-pores. Either mechanism can enhance T2 relaxation by up to three orders of magnitude relative to their soft-tissue counterparts. Detection of these protons requires solid-state techniques that have emerged in recent years and that promise to add a new dimension to the study of hard tissues. Alternative approaches to probe calcified tissues exploit their characteristic magnetic properties. Bone, teeth and extra-osseous calcium-containing biomaterials are unique in that they are more diamagnetic than all other tissues and thus yield information indirectly by virtue of the induced magnetic fields present in their vicinity. Progress has also been made in methods allowing very high-resolution structural imaging of trabecular and cortical bone relying on detection of the surrounding soft-tissues. This brief review, much of it drawn from work conducted in the author's laboratory, seeks to highlight opportunities with focus on early-stage developments for image-based assessment of structure, function, physiology and mechanics of calcified tissues in humans via liquid and solid-state approaches, including proton, deuteron and phosphorus NMR and MRI. PMID:23414678

Wehrli, Felix W

2013-01-10

312

Magnetic resonance of calcified tissues  

NASA Astrophysics Data System (ADS)

MRI of the human body is largely made possible by the favorable relaxation properties of protons of water and triacyl glycerides prevalent in soft tissues. Hard tissues - key among them bone - are generally less amenable to measurement with in vivo MR imaging techniques, not so much as a result of the lower proton density but rather due to the extremely short life-times of the proton signal in water bound to solid-like entities, typically collagen, or being trapped in micro-pores. Either mechanism can enhance T2 relaxation by up to three orders of magnitude relative to their soft-tissue counterparts. Detection of these protons requires solid-state techniques that have emerged in recent years and that promise to add a new dimension to the study of hard tissues. Alternative approaches to probe calcified tissues exploit their characteristic magnetic properties. Bone, teeth and extra-osseous calcium-containing biomaterials are unique in that they are more diamagnetic than all other tissues and thus yield information indirectly by virtue of the induced magnetic fields present in their vicinity. Progress has also been made in methods allowing very high-resolution structural imaging of trabecular and cortical bone relying on detection of the surrounding soft-tissues. This brief review, much of it drawn from work conducted in the author's laboratory, seeks to highlight opportunities with focus on early-stage developments for image-based assessment of structure, function, physiology and mechanics of calcified tissues in humans via liquid and solid-state approaches, including proton, deuteron and phosphorus NMR and MRI.

Wehrli, Felix W.

2013-04-01

313

Reproducibility of Activation Maps for Longitudinal Studies of Visual Function by Functional Magnetic Resonance Imaging  

PubMed Central

Purpose. To test the intra- and intersubject reproducibility of brain activation patterns that underlie visually guided saccades and word recognition in normally sighted subjects and patients with macular degeneration using functional magnetic resonance imaging (fMRI). Methods. Ten normally sighted subjects and five patients with macular degeneration were asked to perform two visually guided saccade tasks and two word-recognition tasks during fMRI with behavioral monitoring. The fMRI measurements were repeated three times at intervals of at least 4 weeks between sessions. The intrasubject reproducibility of the brain activation patterns was examined in a model-independent manner by comparing the distributions of activation across the frontal, parietal, temporal, and occipital brain lobes using Intraclass Correlation Coefficients (ICCs). Intersubject reproducibility was examined by repeated-measure ANOVA. Results. Control subjects showed overall higher intrasubject reproducibility of brain activation patterns (75% ICCs > 0.5) than that of patients with macular degeneration (56% ICCs > 0.5). The intrasubject reproducibility for the patients improved when the target location was fixed, as in the word-recognition tasks (75% ICCs > 0.5), compared with the visually saccade tasks (37% ICCs > 0.5). Intersubject variability of brain activation patterns was strikingly high for both the control and patient groups. Conclusions. The fMRI method can serve as a reliable within-subjects measure of brain activation that has potential for measuring longitudinal changes in brain networks associated with rehabilitation training. Striking intersubject variability reflected at the level of lobes of the brain among control subjects with similar behavioral performance, suggests individual analysis is necessary when implementing longitudinal brain activation studies.

Ming, Jing; Thulborn, Keith R.; Szlyk, Janet P.

2012-01-01

314

Magnetic Resonance Characterization of Ischemic Tissue Metabolism  

PubMed Central

Magnetic resonance imaging (MRI) and spectroscopy (MRS) are versatile diagnostic techniques capable of characterizing the complex stroke pathophysiology, and hold great promise for guiding stroke treatment. Particularly, tissue viability and salvageability are closely associated with its metabolic status. Upon ischemia, ischemic tissue metabolism is disrupted including altered metabolism of glucose and oxygen, elevated lactate production/accumulation, tissue acidification and eventually, adenosine triphosphate (ATP) depletion and energy failure. Whereas metabolism impairment during ischemic stroke is complex, it may be monitored non-invasively with magnetic resonance (MR)-based techniques. Our current article provides a concise overview of stroke pathology, conventional and emerging imaging and spectroscopy techniques, and data analysis tools for characterizing ischemic tissue damage.

Cheung, Jerry S; Wang, Xiaoying; Zhe Sun, Phillip

2011-01-01

315

A bandwidth indicator for magnetic resonance imagers.  

PubMed

Signal-to-noise ratios in magnetic resonance imaging are crucial in determining image quality, and dependent on a number of factors, one being the signal bandwidth per pixel. Not all manufacturers clearly state the bandwidth per pixel used for all sequences. A small battery-powered portable device is described which produces bright sharp lines on the magnetic resonance image at 10 kHz intervals in the frequency encoding direction. The bandwidth per pixel can then easily be calculated using electronic distance callipers, provided the image matrix and field of view are known. The device is expected to be especially of value when acceptance testing on poorly documented imaging systems. PMID:9167164

Date, T; Redpath, T W; Bussell, D M

1997-05-01

316

Magnetic resonance imaging of a mediastinal ependymoma.  

PubMed

Ependymomas typically occur in the brain and spinal cord, and represent 5% and 16% of primary intracranial and spinal cord tumors respectively. Ependymomas arising outside the central nervous systems are uncommon and when they do occur are usually seen in the sacrococcygeal region. Other reported sites include the pelvis, spinal nerve roots, and lung. An extraspinal mediastinal ependymoma is a rare occurrence, with only two previously reported cases to our knowledge. In both instances, the lesion arose in the posterior mediastinum, and were imaged with either chest radiographs alone or chest radiographs and computed tomography. In our case, plain radiography was followed by magnetic resonance imaging. This report documents the clinical, pathological, and magnetic resonance imaging findings in a case of a posterior mediastinal ependymoma. Primary mediastinal ependymomas are rare lesions that may be considered in the differential diagnosis of a posterior mediastinal mass. PMID:9785637

Neumann, D P; Scholl, R J; Kellet, H M; Simon, R H

1998-09-01

317

The posterior parietal paradox: Why do functional magnetic resonance imaging and lesion studies on episodic memory produce conflicting results?  

PubMed

Recent functional magnetic resonance imaging (fMRI) studies addressing healthy subjects point towards posterior parietal cortex (PPC) involvement in episodic memory tasks. This is noteworthy, since neuropsychological studies usually do not connect parietal lesions to episodic memory impairments. Therefore an inventory of the possible factors behind this apparent paradox is warranted. This review compared fMRI studies which demonstrated PPC activity in episodic memory tasks, with findings with studies of patients with PPC lesions. A systematic evaluation of possible explanations for the posterior parietal paradox indicates that PPC activation in fMRI studies does not appear to be attributable to confounding cognitive/psychomotor processes, such as button pressing or stimulus processing. What may be of more importance is the extent to which an episodic memory task loads on three closely related cognitive processes: effort and attention, self-related activity, and scene and image construction. We discuss to what extent these cognitive processes can account for the paradox between lesion and fMRI results. They are strongly intertwined with the episodic memory and may critically determine in how far the PPC plays a role in a given memory task. Future patient studies might profit from specifically taking these cognitive factors into consideration in the task design. PMID:21366885

Schoo, L A; van Zandvoort, M J E; Biessels, G J; Kappelle, L J; Postma, A; de Haan, E H F

2011-03-01

318

Cardiac magnetic resonance imaging in Turner syndrome.  

PubMed

Girls and women with Turner syndrome (TS) have a highly increased morbidity as the result of cardiovascular disease, both congenital and acquired. Increased clinical use of cardiac magnetic resonance imaging (CMR) in patients with TS over recent years has allowed for characterization of disease not always possible with standard imaging modalities, such as echocardiography (echo). In this review, we discuss the current literature regarding CMR in patients with TS and guidelines for its use. PMID:23336808

Gutmark-Little, Iris; Backeljauw, Philippe F

2013-05-01

319

Sensorineural Hearing Loss after Magnetic Resonance Imaging  

PubMed Central

Magnetic resonance imaging (MRI) devices produce noise, which may affect patient's or operators' hearing. Some cases of hearing impairment after MRI procedure have been reported with different patterns (temporary or permanent, unilateral or bilateral, with or without other symptoms like tinnitus). In this report, a case of bilateral sensorineural hearing loss in an otherwise healthy patient underwent brain MRI was described. The patient's hearing loss was accompanied with tinnitus and was not improved after 3 months of followup.

Mollasadeghi, Abolfazl; Mehrparvar, Amir Houshang; Atighechi, Saeid; Mostaghaci, Mehrdad

2013-01-01

320

Fat Segmentation in Magnetic Resonance Images  

Microsoft Academic Search

\\u000a Over the past two decades, many authors have investigated the use of magnetic resonance imaging (MRI) for the analysis of\\u000a body fat and body fat distribution. However, accurate isolation of fat in MR images is an arduous task when performed manually.\\u000a In order to alleviate this burden, numerous automated and semi-automated segmentation algorithms have been developed for the\\u000a quantification of

David P. Costello; Patrick A. Kenny

321

Magnetic Resonance Imaging Studies of Cigarette Smoking  

Microsoft Academic Search

This chapter reviews studies that have applied magnetic resonance imaging (MRI) toward a better understanding of the neurobiological\\u000a correlates and consequences of cigarette smoking and nicotine dependence. The findings demonstrate that smokers differ from\\u000a nonsmokers in regional brain structure and neurochemistry, as well as in activation in response to smoking-related stimuli\\u000a and during the execution of cognitive tasks. We also

Allen Azizian; John Monterosso; Joseph O'Neill; Edythe D. London

322

Magnetic resonance imaging of palindromic rheumatism  

Microsoft Academic Search

A 44-year-old man with intermittent asymmetric migratory oligoarthritis lasting the recent decade was admitted to our hospital.\\u000a Considerable specific biomarkers for rheumatoid arthritis such as anti-agalactosyl IgG antibody are all negative. He was diagnosed\\u000a as palindromic rheumatism (PR). Although hand X-rays showed no remarkable findings, hand magnetic resonance imaging (MRI)\\u000a detected pannus and bone erosion. PR is defined as the

Satoko Ueda; Taro Horino; Kaoru Arii; Tatsuhito Morita; Toshihiro Takao; Kozo Hashimoto

2008-01-01

323

Magnetic resonance imaging in radiotherapy treatment planning  

Microsoft Academic Search

From its inception in the early 1970's up to the present, magnetic resonance imaging (MRI) has evolved into a sophisticated technique, which has aroused considerable interest in var-\\u000aious subelds of medicine including radiotherapy. MRI is capable of imaging in any plane\\u000aand does not use ionizing radiation by virtue of which MRI lends itself admirably to the\\u000apurpose of

Marinus Adriaan Moerland

1996-01-01

324

Magnetic resonance imaging evaluation of myocardial perfusion  

Microsoft Academic Search

Noninvasive qualitative\\/quantitative assessment of myocardial perfusion is considered to be fundamental in the management of known and suspected coronary artery disease patients, as shown by the widespread utilization of thallium-201– and technetium-99m–labeled agents in myocardial single-photon emission computed tomography (SPECT) scintigraphy for diagnostic as well as prognostic purposes. Recently, the availability of subsecond ultrafast magnetic resonance imaging (MRI) sequences (FLASH,

Roberto Passariello; Marcello De Santis

1998-01-01

325

Predicting anxiety in magnetic resonance imaging scans  

Microsoft Academic Search

This study evaluated a brief screening instrument for predicting psychological distress in patients undertaking magnetic resonance\\u000a imaging (MRI) scans. The scale is adapted from Wolpe and Lang’s (1964) Fear Survey Schedule (FSS; see Lukins, Davan, & Drummond,\\u000a 1997). Noise and\\/or confinement were identified as the most unpleasant feature of the MRI by 48.3% of 118 outpatients. The\\u000a MRI-FSS (Lukins et

Lynne M. Harris; Steven R. Cumming; Ross G. Menzies

2004-01-01

326

MAGNETIC RESONANCE MICROSYSTEMS FOR LJFE SCIENCE APPLICATIONS  

Microsoft Academic Search

Nuclear magnetic (MR) resonance spectroscopy and imaging technique are powerful methods available for determining molecular structures and non-invasive 3D imaging. In the effort of developing a nanoMRl microsystem, we have designed, fabricated, assembled and did preliminary characterization of the nanoMRI probe. A multilayer high aspect ratio metal process has been developed for this project. NanoMRI probes are designed through multi-physics

Long-Sheng Fan; C.-L. Cheng; J. Chu; C. Hao; C. Y. Hsieh; S. H. Hsu; A. Chin; K. Hsueh; C.-C. Lee; J. Chang; E. Liu; C. Chien; A. Yeh; J.-H. Chen; W. Wu; C. Lai

327

Magnetic resonance microsystems for life science applications  

Microsoft Academic Search

Nuclear magnetic (MR) resonance spectroscopy and imaging technique are powerful methods available for determining molecular structures and non-invasive 3D imaging. In the effort of developing a nanoMRI microsystem, the authors have designed, fabricated, assembled and did preliminary characterization of the nanoMRI probe. A multilayer high aspect ratio metal process has been developed for this project. NanoMRI probes are designed through

Long-Sheng Fan; W.-S. Huang; C.-L. Cheng; P.-J. Chu; H.-C. Hao; C. Y. Hsieh; S. H. Hsu; A. Chin; K. Hsueh; C.-C. Lee; J. Chang; E. Liu; A. Huang; C. Chien; A. Yeh; J.-H. Chen; W. Wu; C. Lai

2005-01-01

328

magnetic resonance imaging: anthropometric relationships?3  

Microsoft Academic Search

This study compared total and regional adi- pose tissue (AT) and lean tissue (LT) distribution measured by magnetic resonance imaging (MRI) in obese, android women (ii = 40) and men (n = 17). Women had significantly (P < 0.01) greater subcutaneous AT (39.6 ± 11.6 vs 30.7 ± 7.5 L) but significantly (P < 0.01) less visceral AT (2.5 ±

Robert Ross; Kimberley D Shaw; John Rissanen; Yves Martel; Jacques de Guise; Leonard Avruch

329

Claustrophobia and the Magnetic Resonance Imaging Procedure  

Microsoft Academic Search

We examined fear induced by the magnetic resonance imaging (MRI) procedure in 80 adult patients who were undergoing the procedure for the first time. Participants completed self-report measures of claustrophobia, anxiety sensitivity, thoughts about the scan, and pain. Participants were assessed pre- and postscan, and at 1-month follow-up. Twenty-five percent of the participants experienced moderate to severe anx iety during

Heather K. McIsaac; Dana S. Thordarson; Roz Shafran; S. Rachman; Gary Poole

1998-01-01

330

Magnetic resonance imaging: Principles and applications  

SciTech Connect

This text covers the physics underlying magnetic resonance (MR) imaging; pulse sequences; image production; equipment; aspects of clinical imaging; and the imaging of the head and neck, thorax, abdomen and pelvis, and musculoskeletal system; and MR imaging. The book provides about 150 examples of MR images that give an overview of the pathologic conditions imaged. There is a discussion of the physics of MR imaging and also on the spin echo.

Kean, D.; Smith, M.

1986-01-01

331

Magnetic Resonance Imaging of the Kidney  

Microsoft Academic Search

\\u000a This chapter describes the correct imaging technique for the magnetic resonance (MR) examination of the kidney, from the fundamental\\u000a morphologic sequences to the MR urography sequences up to diffusion sequences. The basic MR features of vascular and infectious\\u000a renal diseases and solid benign and malignant renal tumors up to the cystic renal tumors are described. The advanced applications\\u000a of the

Maria Assunta Cova; Marco Cavallaro; Paola Martingano; Maja Ukmar

332

MAGNETIC RESONANCE STUDIES OF SELENIUM CONTAINING COMPOUNDS  

Microsoft Academic Search

The utility of selenium-77 nuclear magnetic resonance in studying the properties of a range of selenium-containing compounds from small organoselenium molecules to macromolecules which contain selenium bound covalently is discussed. Relaxation times, chemical shifts and spin-spin coupling constants are all useful indicators of structure, function and bonding in these systems. The origin of selenium-77 chemical shifts in organoselenium compounds as

R. Bruce Dunlap; Jerome D. Odom

1988-01-01

333

Magnetic resonance spectroscopy in cancer diagnostics  

Microsoft Academic Search

Magnetic resonance spectroscopy (MRS) is one of the most powerful analytical techniques, being frequently used to derive physical,\\u000a chemical, electronic, and structural information about molecules. Considering its potentialities and its evolution as cell\\/tissue\\u000a response predictor, it can be used to detect changes in the tumor pathophysiology before, during, and after treatment. Of\\u000a particular relevance to this analysis, due to its

Ana Margarida Abrantes; Joana Rio; Ludgero C. Tavares; Rui A. Carvalho; Maria Filomena Botelho

2010-01-01

334

Neurosurgical uses for intraprocedural magnetic resonance imaging.  

PubMed

Neurosurgical procedures demand precision, and efforts to create accurate neurosurgical navigation have been central to the profession through its history. Magnetic resonance image (MRI)-guided navigation offers the possibility of real-time, image-based stereotactic information for the neurosurgeon, which makes possible a number of diagnostic and therapeutic procedures. This article will review both current options for intraoperative MRI operative suite arrangements and the current therapeutic/diagnostic uses of intraoperative MRI. PMID:16924171

Mutchnick, Ian S; Moriarty, Thomas M

2005-10-01

335

A computational multiresolution BOLD fMRI model  

PubMed Central

Blood oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI) is a widely used method for brain mapping. BOLD fMRI signal detection is based on an intravoxel dephasing mechanism. This model involves bulk nuclear spin precession in a BOLD-induced inhomogeneous magnetic field within a millimeter-resolution voxel, that is, BOLD signal formation spans a huge spatial scale range from Angstrom to millimeter. In this letter, we present a computational model for multiresolution BOLD fMRI simulation, which consists of partitioning the nuclear spin pool into spin packets at a mesoscopic scale (~10?6m), and calculating multiresolution voxel signals by grouping spin packets at a macroscopic scale range (10?5-10?3m). Under a small angle approximation, we find that the BOLD signal intensity is related to its phase counterpart (or BOLD fieldmap) across two spatial resolution levels.

Chen, Zikuan; Calhoun, Vince

2011-01-01

336

Hyperpolarized xenon magnetic resonance of the lung and the brain  

NASA Astrophysics Data System (ADS)

Hyperpolarized noble gas Magnetic Resonance Imaging (MRI) is a new diagnostic modality that has been used successfully for lung imaging. Xenon is soluble in blood and inhaled xenon is transported to the brain via circulating blood. Xenon also accumulates in the lipid rich white matter of the brain. Hyperpolarized xenon can hence be used as a tissue- sensitive probe of brain function. The goals of this study were to identify the NMR resonances of xenon in the rat brain and evaluate the role of hyperpolarized xenon for brain MRI. We have developed systems to produce sufficient volumes of hyperpolarized xenon for in vivo brain experiments. The specialized instrumentation developed include an apparatus for optical pump-cell manufacture and high purity gas manifolds for filling cells. A hyperpolarized gas delivery system was designed to ventilate small animals with hyperpolarized xenon for transport to the brain. The T1 of xenon dissolved in blood indicates that the lifetime of xenon in the blood is sufficient for significant magnetization to be transferred to distal tissues. A variety of carrier agents for intravenous delivery of hyperpolarized xenon were tested for transport to distal tissues. Using our new gas delivery system, high SNR 129Xe images of rat lungs were obtained. Spectroscopy with hyperpolarized xenon indicated that xenon was transported from the lungs to the blood and tissues with intact magnetization. After preliminary studies that indicated the feasibility for in vivo rat brain studies, experiments were performed with adult rats and young rats with different stages of white matter development. Both in vivo and in vitro experiments showed the prominence of one peak from xenon in the rat brain, which was assigned to brain lipids. Cerebral brain perfusion was calculated from the wash-out of the hyperpolarized xenon signal in the brain. An increase in brain perfusion during maturation was observed. These experiments showed that hyperpolarized xenon MRI can be used to develop unique approaches to studying white matter and gray matter in the brain. Some of the possible applications of hyperpolarized xenon MRI in the brain are clinical diagnosis of white matter diseases, functional MRI (fMRI) and measurement of cerebral blood perfusion.

Venkatesh, Arvind Krishnamachari

2001-04-01

337

GABA concentrations in the human anterior cingulate cortex predict negative BOLD responses in fMRI.  

PubMed

The human anterior cingulate cortex (ACC) is part of the default-mode network that shows predominant negative blood oxygen level-dependent (BOLD) responses in functional magnetic resonance imaging (fMRI). We combined fMRI during emotional processing and resting-state magnetic resonance spectroscopy measurements and observed that the concentration of GABA in the ACC specifically correlated with the amount of negative BOLD responses in the very same region. Our findings show that default-mode network negative BOLD responses during emotions are mediated by GABA. PMID:17982452

Northoff, Georg; Walter, Martin; Schulte, Rolf F; Beck, Johannes; Dydak, Ulrike; Henning, Anke; Boeker, Heinz; Grimm, Simone; Boesiger, Peter

2007-11-04

338

Travelling-wave nuclear magnetic resonance.  

PubMed

Nuclear magnetic resonance (NMR) is one of the most versatile experimental methods in chemistry, physics and biology, providing insight into the structure and dynamics of matter at the molecular scale. Its imaging variant-magnetic resonance imaging (MRI)-is widely used to examine the anatomy, physiology and metabolism of the human body. NMR signal detection is traditionally based on Faraday induction in one or multiple radio-frequency resonators that are brought into close proximity with the sample. Alternative principles involving structured-material flux guides, superconducting quantum interference devices, atomic magnetometers, Hall probes or magnetoresistive elements have been explored. However, a common feature of all NMR implementations until now is that they rely on close coupling between the detector and the object under investigation. Here we show that NMR can also be excited and detected by long-range interaction, relying on travelling radio-frequency waves sent and received by an antenna. One benefit of this approach is more uniform coverage of samples that are larger than the wavelength of the NMR signal-an important current issue in MRI of humans at very high magnetic fields. By allowing a significant distance between the probe and the sample, travelling-wave interaction also introduces new possibilities in the design of NMR experiments and systems. PMID:19225521

Brunner, David O; De Zanche, Nicola; Fröhlich, Jürg; Paska, Jan; Pruessmann, Klaas P

2009-02-19

339

Magnetic resonance venography and liver transplant complications  

PubMed Central

Hepatic vein stenosis is a rare but serious complication following liver transplantation. Multiple modalities can be utilized to image the hepatic vasculature. Magnetic resonance venography (MRV) provides certain advantages over ultrasound, computed tomography angiography and digital subtraction venography. MRV utilizes the same imaging principles of magnetic resonance angiography in order to image the venous system. Blood pool contrast agents, specifically gadofosveset trisodium, allow for steady state imaging up to 1 h following injection, with improved visualisation of vital venous structures by utilising delayed steady state imaging. Additionally, the inherent physics properties of magnetic resonance imaging also provide excellent soft tissue detail and thus help define the extent of complications that often plague the post-liver transplant patient. This case report describes the use of gadofosveset trisodium in a patient with hepatic venous stenosis following liver transplantation. Initial venography failed to outline the stenoses and thus MRV using a blood pool contrast agent was utilised in order to delineate the anatomy and plan a therapeutic endovascular procedure.

Strovski, Evgeny; Liu, Dave; Scudamore, Charles; Ho, Stephen; Yoshida, Eric; Klass, Darren

2013-01-01

340

Magnetic resonance venography and liver transplant complications.  

PubMed

Hepatic vein stenosis is a rare but serious complication following liver transplantation. Multiple modalities can be utilized to image the hepatic vasculature. Magnetic resonance venography (MRV) provides certain advantages over ultrasound, computed tomography angiography and digital subtraction venography. MRV utilizes the same imaging principles of magnetic resonance angiography in order to image the venous system. Blood pool contrast agents, specifically gadofosveset trisodium, allow for steady state imaging up to 1 h following injection, with improved visualisation of vital venous structures by utilising delayed steady state imaging. Additionally, the inherent physics properties of magnetic resonance imaging also provide excellent soft tissue detail and thus help define the extent of complications that often plague the post-liver transplant patient. This case report describes the use of gadofosveset trisodium in a patient with hepatic venous stenosis following liver transplantation. Initial venography failed to outline the stenoses and thus MRV using a blood pool contrast agent was utilised in order to delineate the anatomy and plan a therapeutic endovascular procedure. PMID:24106414

Strovski, Evgeny; Liu, Dave; Scudamore, Charles; Ho, Stephen; Yoshida, Eric; Klass, Darren

2013-09-28

341

Magnetic levitation of metamaterial bodies enhanced with magnetostatic surface resonances  

Microsoft Academic Search

We propose that macroscopic objects built from negative-permeability metamaterials may experience resonantly enhanced magnetic force in low-frequency magnetic fields. Resonant enhancement of the time-averaged force originates from magnetostatic surface resonances (MSR) which are analogous to the electrostatic resonances of negative-permittivity particles, well known as surface plasmon resonances in optics. We generalize the classical problem of MSR of a homogeneous object

Yaroslav Urzhumov; Wenchen Chen; Chris Bingham; Willie Padilla; David R. Smith

2011-01-01

342

Use of magnetic resonance imaging and magnetic resonance angiography in diagnosis of sigmoid sinus thrombosis.  

PubMed

Magnetic resonance angiography is an established radiologic technique which is rapidly becoming useful in imaging the head and neck. Currently, this imaging modality is important in the diagnosis of sigmoid sinus thrombosis caused by otologic disease. Since the introduction of antibiotic therapy, the percentage of deaths attributed to intracranial complications from otitic disease has decreased from 2.5 to approximately 0.25% of documented deaths. Also, the incidence of sinus thrombosis within this group has decreased, but it is still a serious and potentially lethal condition. Sinus thrombosis is suspected clinically when mastoid disease progresses, with picket fence fever pattern, chills, headaches and signs of papilledema. Definitive diagnosis is necessary before surgical treatment. The Queckenstedt test is unreliable, computed tomography is better suited for demonstrating thrombosis of the sagittal sinus rather than the sigmoid sinus, and conventional angiography (although it provides excellent visualization) has the hazard of ionizing radiation and requires vessel puncture and the use of intraarterial contrast agents. We present two cases of thrombosis of the sigmoid sinus as an intracranial otologic complication which were diagnosed definitively with magnetic resonance imaging and magnetic resonance angiography. The combination of magnetic resonance imaging, which showed the thrombosis displaying abnormal signal intensity, and magnetic resonance angiography, which demonstrated the absence of flow in the sinus, was an ideal diagnostic tool. For both patients, treatment consisted of mastoidectomy, sigmoid sinus decompression and antibiotics. PMID:9248135

Davison, S P; Facer, G W; McGough, P F; McCaffrey, T V; Reder, P A

1997-07-01

343

Magnetic Resonance Microscopy of Collagen Mineralization  

PubMed Central

A model mineralizing system was subjected to magnetic resonance microscopy to investigate how water proton transverse (T2) relaxation times and magnetization transfer ratios can be applied to monitor collagen mineralization. In our model system, a collagen sponge was mineralized with polymer-stabilized amorphous calcium carbonate. The lower hydration and water proton T2 values of collagen sponges during the initial mineralization phase were attributed to the replacement of the water within the collagen fibrils by amorphous calcium carbonate. The significant reduction in T2 values by day 6 (p < 0.001) was attributed to the appearance of mineral crystallites, which were also detected by x-ray diffraction and scanning electron microscopy. In the second phase, between days 6 and 13, magnetic resonance microscopy properties appear to plateau as amorphous calcium carbonate droplets began to coalesce within the intrafibrillar space of collagen. In the third phase, after day 15, the amorphous mineral phase crystallized, resulting in a reduction in the absolute intensity of the collagen diffraction pattern. We speculate that magnetization transfer ratio values for collagen sponges, with similar collagen contents, increased from 0.25 ± 0.02 for control strips to a maximum value of 0.31 ± 0.04 at day 15 (p = 0.03) because mineral crystals greatly reduce the mobility of the collagen fibrils.

Chesnick, Ingrid E.; Mason, Jeffrey T.; Giuseppetti, Anthony A.; Eidelman, Naomi; Potter, Kimberlee

2008-01-01

344

Electro-mechanical resonant magnetic field sensor  

NASA Astrophysics Data System (ADS)

We describe a new type of magnetic field sensor, which is termed as an Electro-Mechanical Resonant Sensor (EMRS). The key part of this sensor is a small conductive elastic element with low damping rate and therefore, a high /Q fundamental mode of frequency f1. An AC current is driven through the elastic element which, in the presence of a magnetic field, causes an AC force on the element. When the frequency of the AC current matches the resonant frequency of the element, maximum vibration of the element occurs and this can be measured precisely by optical means. We have built and tested a model sensor of this type by using for the elastic element, a length of copper wire of diameter 0.030mm formed into a loop shape. The wire motion was measured using a light-emitting diode photo-transistor assembly. This sensor demonstrated a sensitivity better than 0.001G for an applied magnetic field of ~1G and a good selectivity for the magnetic field direction. The sensitivity can be easily improved by a factor of /~10-100 by a more sensitive measurement of the elastic element motion and by having the element in vacuum to reduce the drag force.

Temnykh, Alexander B.; Lovelace, Richard V. E.

2002-05-01

345

The role of functional magnetic resonance imaging in the study of brain development, injury, and recovery in the newborn.  

PubMed

Development of brain functions and the structural-functional correlates of brain injury remain difficult to evaluate in the young infant. Thus, new noninvasive methods capable of early functional diagnosis are needed. This review describes the use of functional magnetic resonance imaging (fMRI) for studying localization of brain function in the developing brain when standard clinical investigations are not available or conclusive. This promising neuroimaging technique has been successfully used in healthy newborns and in newborns with brain injury using different paradigms, including passive visual, somato-sensorial, and auditory stimulation. We summarize the major findings of previous fMRI studies in young infants, describe ongoing methodological challenges, and propose exciting future developments in using resting-state protocols and functional connectivity techniques to assist in evaluating early life brain function and its recovery from injury. PMID:20109975

Seghier, Mohamed L; Hüppi, Petra S

2010-02-01

346

fMRI Repetition Suppression: Neuronal Adaptation or Stimulus Expectation?  

PubMed Central

Measurements of repetition suppression with functional magnetic resonance imaging (fMRI adaptation) have been used widely to probe neuronal population response properties in human cerebral cortex. fMRI adaptation techniques assume that fMRI repetition suppression reflects neuronal adaptation, an assumption that has been challenged on the basis of evidence that repetition-related response changes may reflect unrelated factors, such as attention and stimulus expectation. Specifically, Summerfield et al. (Summerfield C, Trittschuh EH, Monti JM, Mesulam MM, Egner T. 2008. Neural repetition suppression reflects fulfilled perceptual expectations. Nat Neurosci. 11:1004–1006) reported that the relative frequency of stimulus repetitions and non-repetitions influenced the magnitude of repetition suppression in the fusiform face area, suggesting that stimulus expectation accounted for most of the effect of repetition. We confirm that stimulus expectation can significantly influence fMRI repetition suppression throughout visual cortex and show that it occurs with long as well as short adaptation durations. However, the effect was attention dependent: When attention was diverted away from the stimuli, the effects of stimulus expectation completely disappeared. Nonetheless, robust and significant repetition suppression was still evident. These results suggest that fMRI repetition suppression reflects a combination of neuronal adaptation and attention-dependent expectation effects that can be experimentally dissociated. This implies that with an appropriate experimental design, fMRI adaptation can provide valid measures of neuronal adaptation and hence response specificity.

Smith, Andrew T.

2012-01-01

347

Multifunctional magnetic nanoparticles for magnetic resonance imaging and cancer therapy  

Microsoft Academic Search

We have developed a multi-layer approach for the synthesis of water-dispersible superparamagnetic iron oxide nanoparticles for hyperthermia, magnetic resonance imaging (MRI) and drug delivery applications. In this approach, iron oxide core nanoparticles were obtained by precipitation of iron salts in the presence of ammonia and provided ?-cyclodextrin and pluronic polymer (F127) coatings. This formulation (F127250) was highly water dispersible which

Murali M. Yallapu; Shadi F. Othman; Evan T. Curtis; Brij K. Gupta; Meena Jaggi; Subhash C. Chauhan

2011-01-01

348

Function Biomedical Informatics Research Network Recommendations for Prospective Multi-Center Functional Magnetic Resonance Imaging Studies  

PubMed Central

This report provides practical recommendations for the design and execution of Multi-Center functional Magnetic Resonance Imaging (MC-fMRI) studies based on the collective experience of the Function Biomedical Informatics Research Network (FBIRN). The paper was inspired by many requests from the fMRI community to FBIRN group members for advice on how to conduct MC-fMRI studies. The introduction briefly discusses the advantages and complexities of MC-fMRI studies. Prerequisites for MC-fMRI studies are addressed before delving into the practical aspects of carefully and efficiently setting up a MC-fMRI study. Practical multi-site aspects include: (1) establishing and verifying scan parameters including scanner types and magnetic fields, (2) establishing and monitoring of a scanner quality program, (3) developing task paradigms and scan session documentation, (4) establishing clinical and scanner training to ensure consistency over time, (5) developing means for uploading, storing, and monitoring of imaging and other data, (6) the use of a traveling fMRI expert and (7) collectively analyzing imaging data and disseminating results. We conclude that when MC-fMRI studies are organized well with careful attention to unification of hardware, software and procedural aspects, the process can be a highly effective means for accessing a desired participant demographics while accelerating scientific discovery.

Glover, Gary H.; Mueller, Bryon A.; Turner, Jessica A.; van Erp, Theo G.M.; Liu, Thomas T.; Greve, Douglas N.; Voyvodic, James T.; Rasmussen, Jerod; Brown, Gregory G.; Keator, David B.; Calhoun, Vince D.; Lee, Hyo Jong; Ford, Judith M.; Mathalon, Daniel H.; Diaz, Michele; O'Leary, Daniel S.; Gadde, Syam; Preda, Adrian; Lim, Kelvin O.; Wible, Cynthia G.; Stern, Hal S.; Belger, Aysenil; McCarthy, Gregory; Ozyurt, Burak; Potkin, Steven G.

2011-01-01

349

Gadolinium-Enhanced Magnetic Resonance Angiography for Pulmonary Embolism  

PubMed Central

Background The accuracy of gadolinium-enhanced magnetic resonance pulmonary angiography and magnetic resonance venography for diagnosing pulmonary embolism has not been determined conclusively. Objective To investigate performance characteristics of magnetic resonance angiography, with or without magnetic resonance venography, for diagnosing pulmonary embolism. Design Prospective, multicenter study from 10 April 2006 to 30 September 2008. (ClinicalTrials.gov registration number: NCT00241826) Setting 7 hospitals and their emergency services. Patients 371 adults with diagnosed or excluded pulmonary embolism. Measurements Sensitivity, specificity, and likelihood ratios were measured by comparing independently read magnetic resonance imaging with the reference standard for diagnosing pulmonary embolism. Reference standard diagnosis or exclusion was made by using various tests, including computed tomographic angiography and venography, ventilation–perfusion lung scan, venous ultra-sonography, D-dimer assay, and clinical assessment. Results Magnetic resonance angiography, averaged across centers, was technically inadequate in 25% of patients (92 of 371). The proportion of technically inadequate images ranged from 11% to 52% at various centers. Including patients with technically inadequate images, magnetic resonance angiography identified 57% (59 of 104) with pulmonary embolism. Technically adequate magnetic resonance angiography had a sensitivity of 78% and a specificity of 99%. Technically adequate magnetic resonance angiography and venography had a sensitivity of 92% and a specificity of 96%, but 52% of patients (194 of 370) had technically inadequate results. Limitation A high proportion of patients with suspected embolism was not eligible or declined to participate. Conclusion Magnetic resonance pulmonary angiography should be considered only at centers that routinely perform it well and only for patients for whom standard tests are contraindicated. Magnetic resonance pulmonary angiography and magnetic resonance venography combined have a higher sensitivity than magnetic resonance pulmonary angiography alone in patients with technically adequate images, but it is more difficult to obtain technically adequate images with the 2 procedures. Primary Funding Source National Heart, Lung, and Blood Institute.

Stein, Paul D.; Chenevert, Thomas L.; Fowler, Sarah E.; Goodman, Lawrence R.; Gottschalk, Alexander; Hales, Charles A.; Hull, Russell D.; Jablonski, Kathleen A.; Leeper, Kenneth V.; Naidich, David P.; Sak, Daniel J.; Sostman, H. Dirk; Tapson, Victor F.; Weg, John G.; Woodard, Pamela K.

2011-01-01

350

The study of pain with blood oxygen level dependent functional magnetic resonance imaging  

NASA Astrophysics Data System (ADS)

Using blood oxygen level dependent functional magnetic resonance imaging (BOLD FMRI), the brain areas activated by pain were studied. These initial studies led to interesting new findings about the body's response to pain and to the refinement of one method used in FMRI analysis for correction of physiologic noise (signal fluctuations caused by the cyclic and non-cyclic changes in the cardiovascular and respiratory status of the body). In the first study, evidence was provided suggesting that the multiple painful stimulations used in typical pain FMRI block designs may cause attenuation over time of the BOLD signal within activated areas. The effect this may have on pain investigations using multiple tasks has not been previously investigated. The demonstrated BOLD attenuation seems unique to pain studies. Several possible explanations exist, but two of the most likely are neural activity modulation by descending pain inhibitory mechanisms and changing hemodynamics caused by a physiologic response to pain. The second study began the investigation of hemodynamics by monitoring the physiologic response to pain for eight subjects in two phases. Phase one used a combination of standard operating suite monitors and research equipment to characterizing the physiologic response to pain. Phase two collected magnetic resonance quantitative flow images during painful nerve stimulation to test for changes in global cerebral blood flow. It is well established that changes in respiration and global blood flow can affect the BOLD response, leading to the final investigation of this dissertation. The brain activation induced by pain for the same eight subjects used in the physiologic response experiments described above was then studied by BOLD FMRI. By including the respiration signal and end-tidal carbon dioxide levels in the analysis of the images, the quantification and removal of image intensity variations correlated to breathing and end-tidal carbon dioxide changes could be performed. The technique generally accepted for this analysis, however, uses respiration signals averaged over a 3 second period. Because normal respiratory rate is approximately one breath every 3 to 5 seconds, it was hypothesized that performing the correction using the average breathing data set would miss much of the actual respiration induced variation in each image. Therefore, a new technique for removing signal that covaries with the actual breathing values present during the collection of each image was introduced. (Abstract shortened by UMI.)

Ibinson, James W.

351

Evaluation of Spatial Working Memory Function in Children and Adults with Fetal Alcohol Spectrum Disorders: A Functional Magnetic Resonance Imaging Study  

Microsoft Academic Search

Magnetic resonance imaging (MRI) and functional MRI stud- ies involving n-back spatial working memory (WM) tasks were conducted in adults and children with Fetal Alcohol Spectrum Disorders (FASD), and in age- and sex-matched controls. FMRI experiments demonstrated consistent activations in regions of the brain associated with working memory. Children with FASD displayed greater inferior-middle frontal lobe activity, while greater superior

KRISZTINA L. MALISZA; AVA-ANN ALLMAN; DEBORAH SHILOFF; LORNA JAKOBSON; SALLY LONGSTAFFE; ALBERT E. CHUDLEY

2005-01-01

352

Effects of Acoustic Gradient Noise from Functional Magnetic Resonance Imaging on Auditory Processing as Reflected by Event-Related Brain Potentials  

Microsoft Academic Search

The processing of sound changes and involuntary attention to them has been widely studied with event-related brain potentials (ERPs). Recently, functional magnetic resonance imaging (fMRI) has been applied to determine the neural mechanisms of involuntary attention and the sources of the corresponding ERP components. The gradient-coil switching noise from the MRI scanner, however, is a challenge to any experimental design

N. Novitski; K. Alho; O. Korzyukov; S. Carlson; S. Martinkauppi; C. Escera; T. Rinne; H. J. Aronen; R. Näätänen

2001-01-01

353

New Insights into the Hemodynamic Blood Oxygenation Level Dependent Response through Combination of Functional Magnetic Resonance Imaging and Optical Recording in Gerbil Barrel Cortex  

Microsoft Academic Search

Fast, low-angle shoot functional magnetic resonance imaging (fMRI), based on the blood oxygenation level-dependent (BOLD) effect, was combined with optical recording of intrinsic signals (ORIS) and 2-deoxyglucose labeling in gerbil barrel cortex. We observed over the activated barrel a positive BOLD signal and increased levels of deoxyhemoglobin and total he- moglobin during each period of prolonged (30 sec) D2 vibrissal

Andreas Hess; Detlef Stiller; Thomas Kaulisch; Peter Heil; Henning Scheich

2000-01-01

354

Too Many Trees to See the Forest: Performance, Event-related Potential, and Functional Magnetic Resonance Imaging Manifestations of Integrative Congenital Prosopagnosia  

Microsoft Academic Search

Neuropsychological, event-related potential (ERP), and func- tional magnetic resonance imaging (fMRI) methods were com- bined to provide a comprehensive description of performance and neurobiological profiles for K.W., a case of congenital proso- pagnosia. We demonstrate that K.W.'s visual perception is characterized by almost unprecedented inability to identify faces, a large bias toward local features, and an extreme deficit in global\\/

Shlomo Bentin; Joseph M. Degutis; Mark D'esposito; Lynn C. Robertson

2007-01-01

355

Brain Activation Modulated by the Comprehension of Normal and Pseudo-word Sentences of Different Processing Demands: A Functional Magnetic Resonance Imaging Study  

Microsoft Academic Search

Recent data from lesion and brain imaging studies have questioned the well-established assumption of a close functional–anatomic link between syntax and Broca's area and semantics and Wernicke's area. In the present study we used functional magnetic resonance imaging (fMRI) to investigate the neuroanatomical correlates of semantic and syntactic functions and possible interdependencies between the related brain systems. In a completely

Brigitte Röder; Oliver Stock; Helen Neville; Siegfried Bien; Frank Rösler

2002-01-01

356

Quantitative Neuromorphometry Using Magnetic Resonance Histology  

PubMed Central

Magnetic resonance imaging (MRI), now common in the clinical domain, has been adapted for use by the neuropathologist by increasing the spatial resolution over 100,000-times what is common in human clinical imaging. This increase in spatial resolution has been accomplished through a variety of technical advances—higher magnetic fields, more sensitive receivers, and clever encoding methods. Magnetic resonance histology (MRH), i.e. the application of MRI to study tissue specimens, now makes three-dimensional imaging of the fixed brain in the cranium routine. Active staining (perfusion fixation with a paramagnetic contrast agent) has allowed us to reduce the scan time by more than 8-times over earlier methods. The result is a three-dimensional isotropic image array that can be viewed along any direction without loss of spatial resolution. Homologous slices can be chosen interactively. Since the tissue is still fully hydrated in the cranium, tissue shrinkage and distortion are virtually eliminated. Volume measurements of neural structures can be made with a high degree of precision and accuracy. MRH will not replace more traditional methods, but it promises enormous value in choosing particular areas and times for more traditional sectioning and assessment.

Johnson, G. Allan; Badea, Alexandra; Jiang, Yi

2010-01-01

357

Magnetic Field Gradient Calibration as an Experiment to Illustrate Magnetic Resonance Imaging  

ERIC Educational Resources Information Center

|A nuclear magnetic resonance (NMR) spectroscopy experiment for the undergraduate physical chemistry laboratory is described that encompasses both qualitative and quantitative pedagogical goals. Qualitatively, the experiment illustrates how images are obtained in magnetic resonance imaging (MRI). Quantitatively, students experience the…

Seedhouse, Steven J.; Hoffmann, Markus M.

2008-01-01

358

Magnetic Field Gradient Calibration as an Experiment to Illustrate Magnetic Resonance Imaging  

ERIC Educational Resources Information Center

A nuclear magnetic resonance (NMR) spectroscopy experiment for the undergraduate physical chemistry laboratory is described that encompasses both qualitative and quantitative pedagogical goals. Qualitatively, the experiment illustrates how images are obtained in magnetic resonance imaging (MRI). Quantitatively, students experience the…

Seedhouse, Steven J.; Hoffmann, Markus M.

2008-01-01

359

Nanodiamond graphitization: a magnetic resonance study.  

PubMed

We report on the first nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR) study of the high-temperature nanodiamond-to-onion transformation. (1)H, (13)C NMR and EPR spectra of the initial nanodiamond samples and those annealed at 600, 700, 800 and 1800 ° C were measured. For the samples annealed at 600 to 800 ° C, our NMR data reveal the early stages of the surface modification, as well as a progressive increase in sp(2) carbon content with increased annealing temperature. Such quantitative experimental data were recorded for the first time. These findings correlate with EPR data on the sensitivity of the dangling bond EPR line width to air content, progressing with rising annealing temperature, that evidences consequent graphitization of the external layers of the diamond core. The sample annealed at 1800 ° C shows complete conversion of nanodiamond particles into carbon onions. PMID:23709490

Panich, A M; Shames, A I; Sergeev, N A; Olszewski, M; McDonough, J K; Mochalin, V N; Gogotsi, Y

2013-05-24

360

Nanodiamond graphitization: a magnetic resonance study  

NASA Astrophysics Data System (ADS)

We report on the first nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR) study of the high-temperature nanodiamond-to-onion transformation. 1H, 13C NMR and EPR spectra of the initial nanodiamond samples and those annealed at 600, 700, 800 and 1800?° C were measured. For the samples annealed at 600 to 800?° C, our NMR data reveal the early stages of the surface modification, as well as a progressive increase in sp2 carbon content with increased annealing temperature. Such quantitative experimental data were recorded for the first time. These findings correlate with EPR data on the sensitivity of the dangling bond EPR line width to air content, progressing with rising annealing temperature, that evidences consequent graphitization of the external layers of the diamond core. The sample annealed at 1800?° C shows complete conversion of nanodiamond particles into carbon onions.

Panich, A. M.; Shames, A. I.; Sergeev, N. A.; Olszewski, M.; McDonough, J. K.; Mochalin, V. N.; Gogotsi, Y.

2013-06-01

361

Biophysical and physiological origins of blood oxygenation level-dependent fMRI signals  

PubMed Central

After its discovery in 1990, blood oxygenation level-dependent (BOLD) contrast in functional magnetic resonance imaging (fMRI) has been widely used to map brain activation in humans and animals. Since fMRI relies on signal changes induced by neural activity, its signal source can be complex and is also dependent on imaging parameters and techniques. In this review, we identify and describe the origins of BOLD fMRI signals, including the topics of (1) effects of spin density, volume fraction, inflow, perfusion, and susceptibility as potential contributors to BOLD fMRI, (2) intravascular and extravascular contributions to conventional gradient-echo and spin-echo BOLD fMRI, (3) spatial specificity of hemodynamic-based fMRI related to vascular architecture and intrinsic hemodynamic responses, (4) BOLD signal contributions from functional changes in cerebral blood flow (CBF), cerebral blood volume (CBV), and cerebral metabolic rate of O2 utilization (CMRO2), (5) dynamic responses of BOLD, CBF, CMRO2, and arterial and venous CBV, (6) potential sources of initial BOLD dips, poststimulus BOLD undershoots, and prolonged negative BOLD fMRI signals, (7) dependence of stimulus-evoked BOLD signals on baseline physiology, and (8) basis of resting-state BOLD fluctuations. These discussions are highly relevant to interpreting BOLD fMRI signals as physiological means.

Kim, Seong-Gi; Ogawa, Seiji

2012-01-01

362

Cardiovascular magnetic resonance imaging in small animals.  

PubMed

Noninvasive imaging studies involving small animals are becoming increasingly important in preclinical pharmacological, genetic, and biomedical cardiovascular research. Especially small animal magnetic resonance imaging (MRI) using high field and clinical MRI systems has gained significant importance in recent years. Compared to other imaging modalities, like computer tomography, MRI can provide an excellent soft tissue contrast, which enables the characterization of different kinds of tissues without the use of contrast agents. In addition, imaging can be performed with high spatial and temporal resolution. Small animal MRI cannot only provide anatomical information about the beating murine heart; it can also provide functional and molecular information, which makes it a unique imaging modality. Compared to clinical MRI examinations in humans, small animal MRI is associated with additional challenges. These included a smaller size of all cardiovascular structures and a up to ten times higher heart rate. Dedicated small animal monitoring devices make a reliable cardiac triggering and respiratory gating feasible. MRI in combination with molecular probes enables the noninvasive imaging of biological processes at a molecular level. Different kinds of iron oxide or gadolinium-based contrast agents can be used for this purpose. Compared to other molecular imaging modalities, like single photon emission computed tomography (SPECT) and positron emission tomography (PET), MRI can also provide imaging with high spatial resolution, which is of high importance for the assessment of the cardiovascular system. The sensitivity for detection of MRI contrast agents is however lower compared to sensitivity of radiation associated techniques like PET and SPECT. This chapter is divided into the following sections: (1) "Introduction," (2) "Principals of Magnetic Resonance Imaging," (3) "MRI Systems for Preclinical Imaging and Experimental Setup," and (4) "Cardiovascular Magnetic Resonance Imaging." PMID:22137434

Botnar, René M; Makowski, Marcus R

2012-01-01

363

Magnetic levitation of metamaterial bodies enhanced with magnetostatic surface resonances  

NASA Astrophysics Data System (ADS)

We propose that macroscopic objects built from negative-permeability metamaterials may experience resonantly enhanced magnetic force in low-frequency magnetic fields. Resonant enhancement of the time-averaged force originates from magnetostatic surface resonances (MSRs), which are analogous to the electrostatic resonances of negative-permittivity particles, well known as surface plasmon resonances in optics. We generalize the classical problem of the MSR of a homogeneous object to include anisotropic metamaterials and consider the most extreme case of anisotropy, where the permeability is negative in one direction but positive in the others. It is shown that deeply subwavelength objects made of such indefinite (hyperbolic) media exhibit a pronounced magnetic dipole resonance that couples strongly to uniform or weakly inhomogeneous magnetic field and provides strong enhancement of the magnetic force, enabling applications such as enhanced magnetic levitation.

Urzhumov, Yaroslav; Chen, Wenchen; Bingham, Chris; Padilla, Willie; Smith, David R.

2012-02-01

364

Measuring nonconstant flow in magnetic resonance imaging.  

PubMed

An attempt is made to quantify rapid flow using magnetic resonance imaging techniques. An analysis is presented in which it is assumed that constant velocity gradients are present. A deconvolution scheme which can remove the blurring from motion with acceleration is developed. This allows improved resolution and velocity determination. Computer experiments were performed on simulated data, where the velocity drops from 100 cm/s to 50 cm/s over a distance of 5 cm. In noise-free data, velocities were recovered to within 2% of the lower velocity and, for data with 5% white noise, to within 6% PMID:18222793

Izen, S H; Haacke, E M

1990-01-01

365

Creating a magnetic resonance imaging ontology.  

PubMed

The goal of this work is to build an ontology of Magnetic Resonance Imaging. The MRI domain has been analysed regarding MRI simulators and the DICOM standard. Tow MRI simulators have been analysed: JEMRIS, which is developed in XML and C++, has a hierarchical organisation and SIMRI, which is developed in C, has a good representation of MRI physical processes. To build the ontology we have used Protégé 4, owl2 that allows quantitative representations. The ontology has been validated by a reasoner (Fact++) and by a good representation of DICOM headers and of MRI processes. The MRI ontology would improved MRI simulators and eased semantic interoperability. PMID:21893854

Lasbleiz, Jérémy; Saint-Jalmes, Hervé; Duvauferrier, Régis; Burgun, Anita

2011-01-01

366

Multiparametric magnetic resonance imaging of prostate cancer  

PubMed Central

In India, prostate cancer has an incidence rate of 3.9 per 100,000 men and is responsible for 9% of cancer-related mortality. It is the only malignancy that is diagnosed with an apparently blind technique, i.e., transrectal sextant biopsy. With increasing numbers of high-Tesla magnetic resonance imaging (MRI) equipment being installed in India, the radiologist needs to be cognizant about endorectal MRI and multiparametric imaging for prostate cancer. In this review article, we aim to highlight the utility of multiparamteric MRI in prostate cancer. It plays a crucial role, mainly in initial staging, restaging, and post-treatment follow-up.

Hedgire, Sandeep S; Oei, Tamara N; Mcdermott, Shaunagh; Cao, Kai; Patel M, Zena; Harisinghani, Mukesh G

2012-01-01

367

Nuclear magnetic resonance study of ultrananocrystalline diamonds  

Microsoft Academic Search

.   \\u000a We report on a nuclear magnetic resonance (NMR) study of \\u000a ultrananocrystalline diamond (UNCD) materials produced by detonation \\u000a technique. Analysis of the 13C and 1H NMR spectra, spin-spin and \\u000a spin-lattice relaxation times in purified UNCD samples is presented. Our \\u000a measurements show that UNCD particles consist of a diamond core that is \\u000a partially covered by a sp\\u000a 2-carbon fullerene-like shell. The

A. M. Panich; A. I. Shames; H.-M. Vieth; E. ?sawa; M. Takahashi

2006-01-01

368

Magnetic Resonance Labeling of Stem Cells  

PubMed Central

Recent meta-analyses of clinical cellular therapy trials in cardiovascular disease have shown that these therapies are safe and perhaps yield a positive therapeutic benefit (1-5). However, 1 issue that has plagued these clinical studies is the inability to determine the percentage engraftment of exogenously administered stem cells and the stem cell fate. In this issue of iJACC, Adler et al. (6) propose a cardiac magnetic resonance (CMR) contrast based on a paramagnetic agent, gadolinium, to track the engraftment of embryonic stem cell-derived cardiovascular progenitor cells.

Kraitchman, Dara L.; Caravan, Peter

2010-01-01

369

Magnetic resonance perfusion imaging without contrast media  

Microsoft Academic Search

Purpose  Principles of magnetic resonance imaging techniques providing perfusion-related contrast weighting without administration\\u000a of contrast media are reported and analysed systematically. Especially common approaches to arterial spin labelling (ASL) perfusion imaging allowing quantitative assessment of specific perfusion rates are described in detail. The potential\\u000a of ASL for perfusion imaging was tested in several types of tissue.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  After a systematic comparison of

Petros Martirosian; Andreas Boss; Christina Schraml; Nina F. Schwenzer; Hansjörg Graf; Claus D. Claussen; Fritz Schick

2010-01-01

370

Cardiovascular magnetic resonance in systemic hypertension  

PubMed Central

Systemic hypertension is a highly prevalent potentially modifiable cardiovascular risk factor. Imaging plays an important role in the diagnosis of underlying causes for hypertension, in assessing cardiovascular complications of hypertension, and in understanding the pathophysiology of the disease process. Cardiovascular magnetic resonance (CMR) provides accurate and reproducible measures of ventricular volumes, mass, function and haemodynamics as well as uniquely allowing tissue characterization of diffuse and focal fibrosis. In addition, CMR is well suited for exclusion of common secondary causes for hypertension. We review the current and emerging clinical and research applications of CMR in hypertension.

2012-01-01

371

Magnetic resonance imaging of the cervix  

PubMed Central

Abstract Due to deficiencies of clinical staging, magnetic resonance (MR) imaging is being increasingly used in the pre-treatment work-up of cervical cancer. Lymph node status, as evaluated by advanced imaging modalities, is also being incorporated into management algorithms. Familiarity with MR imaging features will lead to more accurate staging of cervical cancer. Awareness of impact of staging on management will enable the radiologists to tailor the report to clinically and surgically relevant information. This article emphasizes the guidelines on the MR staging criteria, dependence of newer treatments on imaging staging and lymph node involvement, and MR imaging in post-treatment surveillance of cervical cancer.

Zand, Khashayar Rafat; Reinhold, Caroline; Abe, Hisashi; Maheshwari, Sharad; Mohamed, Ahmed; Upegui, Daniel

2007-01-01

372

Nuclear magnetic resonance imaging - Potential cardiac applications  

SciTech Connect

Potential clinical applications of nuclear magnetic resonance (NMR) imaging are discussed with particular emphasis on cardiac studies. The principles of NMR spectroscopy and the reconstruction of images from NMR data obtained in a magnetic field gradient are reviewed, and the sensitive point technique of Hinshaw et al. (1977) for producing three dimensional images is introduced. Possible uses of NMR imaging in the study of intact functional biological systems are then considered, including the differentiation of ischemic tissue areas including myocardial injuries by the proton NMR imaging of water, and metabolic studies of myocardial ischemia and infarction by P-31 imaging of ATP, creatine phosphate and inorganic phosphorus. Unresolved problems in the application of NMR imaging to clinical studies are pointed out, and possible solutions which would enable the development of the technique as a powerful aid in diagnosing disease are suggested.

Goldman, M.R.; Pohost, G.M.; Ingwall, J.S.; Fossel, E.T.

1980-12-18

373

BOLD magnetic resonance imaging of skeletal muscle.  

PubMed

Blood-oxygen-level-dependent (BOLD) imaging was a concept introduced in 1990 for evaluating brain activation. The method relies on magnetic resonance imaging (MRI) contrast resulting from changes in the microvascular ratio of oxyhaemoglobin (oxyHb) to deoxyhaemoglobin (deoxyHb). OxyHb is diamagnetic, whereas deoxyHb is paramagnetic, which produces a local bulk magnetic susceptibility effect and subsequent MRI signal change. The changes are typically observed in T(2)*-weighted functional MRI scans. However, there has recently been interest in BOLD as a way to evaluate microcirculation of any normal or diseased tissue. This review focuses on the application of BOLD imaging in the understanding of normal and diseased skeletal muscle. In addition we present new findings showing the possible application of BOLD imaging with hyperoxia for evaluating skeletal muscle physiology. PMID:14735429

Noseworthy, Michael D; Bulte, Daniel P; Alfonsi, Jeff

2003-12-01

374

Clinical applications of cardiovascular magnetic resonance imaging  

PubMed Central

Cardiovascular magnetic resonance imaging (MRI) has evolved from an effective research tool into a clinically proven, safe and comprehensive imaging modality. It provides anatomic and functional information in acquired and congenital heart disease and is the most precise technique for quantification of ventricular volumes, function and mass. Owing to its excellent interstudy reproducibility, cardiovascular MRI is the optimal method for assessment of changes in ventricular parameters after therapeutic intervention. Delayed contrast enhancement is an accurate and robust method used in the diagnosis of ischemic and nonischemic cardiomyopathies and less common diseases, such as cardiac sarcoidosis and myocarditis. First-pass magnetic contrast myocardial perfusion is becoming an alternative to radionuclide techniques for the detection of coronary atherosclerotic disease. In this review we outline the techniques used in cardiovascular MRI and discuss the most common clinical applications.

Marcu, Constantin B.; Beek, Aernout M.; van Rossum, Albert C.

2006-01-01

375

Magnetic resonance imaging and safety aspects.  

PubMed

Magnetic resonance imaging (MRI) is a technique that uses a magnetic field and radio waves to create detailed images of the organs and tissues within your body. MRI is safe, but if something goes wrong, it can go very wrong. Most reported cases of MRI-related injuries and the few fatalities that have occurred have apparently been the result of failure to follow safety guidelines or of use of inappropriate or outdated information related to the safety aspects of biomedical implants and devices. To prevent accidents in the MRI environment, therefore, it is necessary to revise information on biologic effects and safety according to changes that have occurred in MRI technology and with regard to current guidelines for biomedical implants and devices. This review provides an overview of and update on MRI biologic effects, discusses new or controversial MRI safety topics and issues, and presents evidence-based guidelines to ensure safety for patients and staff. PMID:21112927

Coskun, Ozlem

2010-11-26

376

Optically detected magnetic resonance (ODMR) of photoexcited triplet states  

Microsoft Academic Search

Optically Detected Magnetic Resonance (ODMR) is a double resonance technique which combines optical measurements (fluorescence,\\u000a phosphorescence, absorption) with electron spin resonance spectroscopy. After the first triplet-state ODMR experiments in\\u000a zero magnetic field reported in 1968 by Schmidt and van der Waals, the number of double resonance studies on excited triplet\\u000a states grew rapidly. Photosynthesis has proven to be a fruitful

Donatella Carbonera

2009-01-01

377

Alcohol induced region-dependent alterations of hemodynamic response: implications for the statistical interpretation of pharmacological fMRI studies  

Microsoft Academic Search

Worldwide, ethanol abuse causes thousands of fatal accidents annually as well as innumerable social dysfunctions and severe\\u000a medical disorders. Yet, few studies have used the blood oxygenation level dependent functional magnetic resonance imaging\\u000a method (BOLD fMRI) to map how alcohol alters brain functions, as fMRI relies on neurovascular coupling, which may change due\\u000a to the vasoactive properties of alcohol. We

M. Luchtmann; K. Jachau; C. Tempelmann; J. Bernarding

2010-01-01

378

Granger Causality Analysis implementation on MATLAB: a graphic user interface toolkit for fMRI data processing  

Microsoft Academic Search

A lot of functional magnetic resonance imaging (fMRI) studies have indicated that Granger causality analysis (GCA) is a suitable method to reveal causal effect among brain regions. Based on another MATLAB GUI toolkit, Resting State fMRI Data Analysis Toolkit (REST), we implemented GCA on MATLAB as a graphical user interface (GUI) toolkit. This toolkit, namely REST-GCA, could output both the

Zhen-Xiang Zang; Chao-Gan Yan; Zhang-Ye Dong; Jian Huang; Yu-Feng Zang

379

Simultaneous measurements of kinematics and fMRI: compatibility assessment and case report on recovery evaluation of one stroke patient  

Microsoft Academic Search

BACKGROUND: Correlating the features of the actual executed movement with the associated cortical activations can enhance the reliability of the functional Magnetic Resonance Imaging (fMRI) data interpretation. This is crucial for longitudinal evaluation of motor recovery in neurological patients and for investigating detailed mutual interactions between activation maps and movement parameters. Therefore, we have explored a new set-up combining fMRI

Claudia Casellato; Simona Ferrante; Marta Gandolla; Nicola Volonterio; Giancarlo Ferrigno; Giuseppe Baselli; Tiziano Frattini; Alberto Martegani; Franco Molteni; Alessandra Pedrocchi

2010-01-01

380

Neural correlates of the “Aha” experiences: Evidence from an fMRI study of insight problem solving  

Microsoft Academic Search

In the present study, we used learning–testing paradigm to examine brain activation of “Aha” effects with event-related functional magnetic resonance imaging (fMRI) during solving Chinese logogriphs. Blood oxygenation level-dependent fMRI contrasts between Aha and No-aha conditions were measured. Increased activities in the precuneus (BA 19\\/7), the left inferior\\/middle frontal gyrus (BA 9\\/6), the inferior occipital gyrus (BA 18), and the

Jiang Qiu; Hong Li; Jerwen Jou; Jia Liu; Yuejia Luo; Tingyong Feng; Zhenzhen Wu; Qinglin Zhang

2010-01-01

381

Improved differentiation of tactile activations in human secondary somatosensory cortex and thalamus using cardiac-triggered fMRI  

Microsoft Academic Search

Functional magnetic resonance imaging (fMRI) can reveal human brain activations with high precision. The accuracy may, however, be impaired by movement and deformation of brain tissue associated with cardiac pulsations. Here we corrected for such artifacts by time-locking the fMRI data acquisition to the cardiac cycle in ten subjects who received tactile stimuli to their lips, fingers, and toes. The

Sanna Malinen; Martin Schürmann; Yevhen Hlushchuk; Nina Forss; Riitta Hari

2006-01-01

382

Effect of Acupuncture on the Brain in Children With Spastic Cerebral Palsy Using Functional Neuroimaging (fMRI)  

Microsoft Academic Search

We study the effect of acupuncture on brain activation patterns in children with cerebral palsy using functional magnetic resonance imaging (fMRI). fMRI of the whole brain was performed in 11 children with cerebral palsy and 10 healthy children during stimulation of a common acupoint in Traditional Medicine [Liv3 (Taichong)] on the left foot. We use both twisting and nontwisting methods

Yun Wu; Zhen Jin; Ke Li; Zhong-Li Lu; Virginia Wong; Tong-Li Han; Hua Zheng; Opher Caspi; Gang Liu; Ya-Wei Zeng; Li-Ping Zou

2008-01-01

383

Propofol attenuates responses of the auditory cortex to acoustic stimulation in a dose-dependent manner: a FMRI study  

Microsoft Academic Search

Background: Functional magnetic resonance imaging (fMRI) using blood-oxygen-level-dependent (BOLD) contrasts is a com- mon method for studying sensory or cognitive brain functions. The aim of the present study was to assess the effect of the intravenous anaesthetic propofol on auditory-induced brain activation using BOLD contrast fMRI. Methods: In eight neurosurgical patients, musical stimuli were presented binaurally in a block design.

M. H. Dueck; F. Petzke; H. J. Gerbershagen; M. Paul; Rainer Goebel; R. Girnus; B. Krug; B. Sorger; R. Lehrke; V. Sturm; U. Boerner

2005-01-01

384

An information-theoretic criterion for intrasubject alignment of FMRI time series: motion corrected independent component analysis  

Microsoft Academic Search

A three-dimensional image registration method for motion correction of functional magnetic resonance imaging (fMRI) time-series, based on independent component analysis (ICA), is described. We argue that movement during fMRI data acquisition results in a simultaneous increase in the joint entropy of the observed time-series and a decrease in the joint entropy of a nonlinear function of the derived spatially independent

Rui Liao; Jeffrey L. Krolik; Martin J. McKeown

2005-01-01

385

Comparison of two exploratory data analysis methods for fMRI: unsupervised clustering versus independent component analysis  

Microsoft Academic Search

Exploratory data-driven methods such as unsupervised clustering and independent component analysis (ICA) are considered to be hypothesis-generating procedures, and are complementary to the hypothesis-led statistical inferential methods in functional magnetic resonance imaging (fMRI). In this paper, we present a comparison between unsupervised clustering and ICA in a systematic fMRI study. The comparative results were evaluated by 1) task-related activation maps,

Anke Meyer-bäse; Axel Wismueller; Oliver Lange

2004-01-01

386

Classification of fMRI Time Series in a Low-Dimensional Subspace With a Spatial Prior  

Microsoft Academic Search

We propose a new method for detecting activation in functional magnetic resonance imaging (fMRI) data. We project the fMRI time series on a low-dimensional subspace spanned by wavelet packets in order to create projections that are as non-Gaussian as possible. Our approach achieves two goals: it re- duces the dimensionality of the problem by explicitly constructing a sparse approximation to

François G. Meyer; Xilin Shen

2008-01-01

387

Cardiac Magnetic Resonance In Adults With Congenital Heart Disease  

PubMed Central

Increasing numbers of adults with congenital heart disease are referred for cardiac magnetic resonance imaging. Knowledge of the congenital heart anatomy, prior surgical interventions, and the development of an imaging focus for each individual patient plays a crucial role when performing a successful cardiac magnetic resonance imaging examination. The following manuscript focuses on cardiac magnetic resonance imaging considerations of three specific conotruncal congenital heart lesions: tetralogy of Fallot, transposition of the great arteries (TGA), and physiologically corrected TGA (c-TGA).

Valente, Anne Marie

2013-01-01

388

Diffusion-weighted magnetic resonance imaging of the temporal bone  

Microsoft Academic Search

This paper summarizes the value of diffusion-weighted magnetic resonance imaging in the evaluation of temporal bone pathology.\\u000a It highlights the use of different types of diffusion-weighted magnetic resonance imaging in the different types of cholesteatoma,\\u000a prior to first stage surgery and prior to second look surgery. The value of diffusion-weighted magnetic resonance imaging\\u000a in the evaluation of pathology of the

B. De Foer; J. P. Vercruysse; M. Spaepen; T. Somers; M. Pouillon; E. Offeciers; J. W. Casselman

2010-01-01

389

A case of persistent visual hallucinations of faces following LSD abuse: a functional Magnetic Resonance Imaging study.  

PubMed

In this study, we report the case of a patient experiencing hallucinations of faces that could be reliably precipitated by looking at trees. Using functional Magnetic Resonance Imaging (fMRI), we found that face hallucinations were associated with increased and decreased neural activity in a number of cortical regions. Within the same fusiform face area, however, we found significant decreased and increased neural activity according to whether the patient was experiencing hallucinations or veridical perception of faces, respectively. These findings may indicate key differences in how hallucinatory and veridical perceptions lead to the same phenomenological experience of seeing faces. PMID:19927262

Iaria, Giuseppe; Fox, Christopher J; Scheel, Michael; Stowe, Robert M; Barton, Jason J S

2009-11-18

390

Nuclear magnetic resonance in compounds of variable composition  

NASA Astrophysics Data System (ADS)

The results of nuclear magnetic resonance studies of the hydrides, carbides, nitrides, and oxides of transition elements are reviewed. The discussion covers general capabilities of the nuclear magnetic resonance method, with emphasis placed on the relationship between the resonance parameters and the electron structure and properties of solids. Attention is also given to the interpretation of nuclear magnetic resonance data on the basis of quantum chemical calculations of the electron structure performed by means of cluster methods of molecular orbitals. The capabilities of the nuclear resonance method in studying the properties and the structure of phases of variable composition are illustrated by examples.

Pletnev, R. N.; Zolotukhina, L. V.; Gubanov, V. A.

391

Resonant circuit as magnetic device for cancer therapy  

NASA Astrophysics Data System (ADS)

Fabrication and characterization of a resonant circuit as magnetic device for hyperthermia treatment are discussed. The resonant circuit consisting of a closed connection of an inductor and a capacitor raised its temperature by an externally applied magnetic field. As the resonant circuit was heated efficiently, it could be excited by a weak RF magnetic field of magnetic resonance imaging (MRI). By using a ferrite core for the inductor, the efficiency of temperature rise of the circuit was improved, which attributed to the miniaturization of the implant size.

Takemura, Yasushi

2011-01-01

392

Sequence of pattern onset responses in the human visual areas: an fMRI constrained VEP source analysis  

Microsoft Academic Search

We measured the timing of activity in distinct functional areas of the human visual cortex after onset of a visual pattern. This is not possible with visual evoked potentials (VEPs) or magnetic fields alone, and direct combination of functional magnetic resonance imaging (fMRI) with electromagnetic data has turned out to be difficult. We tested a relatively new approach, where both

S. Vanni; J. Warnking; M. Dojat; C. Delon-Martin; J. Bullier; C. Segebarthb

2004-01-01

393

Geometric quantum computation using nuclear magnetic resonance  

PubMed

A significant development in computing has been the discovery that the computational power of quantum computers exceeds that of Turing machines. Central to the experimental realization of quantum information processing is the construction of fault-tolerant quantum logic gates. Their operation requires conditional quantum dynamics, in which one sub-system undergoes a coherent evolution that depends on the quantum state of another sub-system; in particular, the evolving sub-system may acquire a conditional phase shift. Although conventionally dynamic in origin, phase shifts can also be geometric. Conditional geometric (or 'Berry') phases depend only on the geometry of the path executed, and are therefore resilient to certain types of errors; this suggests the possibility of an intrinsically fault-tolerant way of performing quantum gate operations. Nuclear magnetic resonance techniques have already been used to demonstrate both simple quantum information processing and geometric phase shifts. Here we combine these ideas by performing a nuclear magnetic resonance experiment in which a conditional Berry phase is implemented, demonstrating a controlled phase shift gate. PMID:10706278

Jones; Vedral; Ekert; Castagnoli

2000-02-24

394

Prospects for neutron probed magnetic resonance imaging  

SciTech Connect

The information gained from magnetic resonance imaging has provided useful insight into many insulators. Extending this technique to conductors requires an alternative means of spin manipulation besides electromagnetic radiation. A method to use neutron measurement of the Zeeman splitting to measure the relaxation time is described. The Zeeman splitting is observed by a neutron spectrometer as an incoherent signal with an energy transfer equal to the Zeeman energy. This energy scale is so small that fields in excess of 15 T are required to sufficiently separate this line from other incoherent processes. Once the Zeeman splitting is observed, a perturbation of the system is required to enable measurement of the nuclear spin relaxation time; the physical quantity measured in a Nuclear Magnetic Resonance experiment. The proposed perturbation is a pulsed field of 10 T. The relaxation of the Zeeman splitting back to the 15 T condition is then recorded as a function of time. The resultant data is the aforementioned measure of the relaxation time. With the ability to measure the relaxation times the image map can be created by rastering the sample with respect to the beam.

Granroth, Garrett E [ORNL

2009-01-01

395

Magnetic resonance imaging. Application to family practice.  

PubMed Central

OBJECTIVE: To review indications, contraindications, and risks of using magnetic resonance imaging (MRI) in order to help primary care physicians refer patients appropriately for MRI, screen for contraindications to using MRI, and educate patients about MRI. QUALITY OF EVIDENCE: Recommendations are based on classic textbooks, the policies of our MRI group, and a literature search using MEDLINE with the MeSH headings magnetic resonance imaging, brain, musculoskeletal, and spine. The search was limited to human, English-language, and review articles. Evidence in favour of using MRI for imaging the head, spine, and joints is well established. For cardiac, abdominal, and pelvic conditions, MRI has been shown useful for certain indications, usually to complement other modalities. MAIN MESSAGE: For demonstrating soft tissue conditions, MRI is better than computed tomography (CT), but CT shows bone and acute bleeding better. Therefore, patients with trauma or suspected intracranial bleeding should have CT. Tumours, congenital abnormalities, vascular structures, and the cervical or thoracic spine show better on MRI. Either modality can be used for lower back pain. Cardiac, abdominal, and pelvic abnormalities should be imaged with ultrasound or CT before MRI. Contraindications for MRI are mainly metallic implants or shrapnel, severe claustrophobia, or obesity. CONCLUSIONS: With the increasing availability of MRI scanners in Canada, better understanding of the indications, contraindications, and risks will be helpful for family physicians and their patients. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10

Goh, R. H.; Somers, S.; Jurriaans, E.; Yu, J.

1999-01-01

396

Magnetic resonance elastography hardware design: a survey.  

PubMed

Magnetic resonance elastography (MRE) is an emerging technique capable of measuring the shear modulus of tissue. A suspected tumour can be identified by comparing its properties with those of tissues surrounding it; this can be achieved even in deep-lying areas as long as mechanical excitation is possible. This would allow non-invasive methods for cancer-related diagnosis in areas not accessible with conventional palpation. An actuating mechanism is required to generate the necessary tissue displacements directly on the patient in the scanner and three different approaches, in terms of actuator action and position, exist to derive stiffness measurements. However, the magnetic resonance (MR) environment places considerable constraints on the design of such devices, such as the possibility of mutual interference between electrical components, the scanner field, and radio frequency pulses, and the physical space restrictions of the scanner bore. This paper presents a review of the current solutions that have been developed for MRE devices giving particular consideration to the design criteria including the required vibration frequency and amplitude in different applications, the issue of MR compatibility, actuation principles, design complexity, and scanner synchronization issues. The future challenges in this field are also described. PMID:19499839

Tse, Z T H; Janssen, H; Hamed, A; Ristic, M; Young, I; Lamperth, M

2009-05-01

397

Cardiovascular applications of nuclear magnetic resonance spectroscopy.  

PubMed

Nuclear magnetic resonance spectroscopy has great potential for defining noninvasively the metabolic status of the heart and skeletal muscle. This technique uses the spin properties of certain nuclei (such as phosphorus-31, hydrogen-1 and carbon-13) to measure high energy phosphates, intracellular pH, lactate and glycogen. Animal studies have formed the basis for human investigations and have demonstrated well-defined changes in high energy phosphates during myocardial ischemia and reperfusion, as well as in cardiomyopathies. Human studies have been limited by issues of sensitivity and localization, although techniques such as rotating frame, depth-resolved surface coil spectroscopy, image-selected in vivo spectroscopy and spectroscopic imaging have been used to acquire phosphorus-31 spectra from the human heart. The few human studies of patients with disease have demonstrated elevated inorganic phosphate peaks after myocardial infarction and abnormal phosphodiester peaks in patients with hypertrophic cardiomyopathy. Studies of patients with heart failure have shown that these patients acidify their peripheral muscles with exercise more easily than do control subjects. Clinical application of nuclear magnetic resonance spectroscopy will depend on technical advances and the demonstration of sensitivity of metabolic changes with disease. PMID:2672766

Schaefer, S

1989-09-01

398

Metabolic Tumor Imaging Using Magnetic Resonance Spectroscopy  

PubMed Central

The adaptability and the genomic plasticity of cancer cells, and the interaction between the tumor microenvironment and co-opted stromal cells, coupled with the ability of cancer cells to colonize distant organs, contribute to the frequent intractability of cancer. It is becoming increasingly evident that personalized molecular targeting is necessary for the successful treatment of this multifaceted and complex disease. Noninvasive imaging modalities such as magnetic resonance (MR), positron emission tomography (PET), and single-photon emission computed tomography (SPECT) are filling several important niches in this era of targeted molecular medicine, in applications that span from bench to bedside. In this review we focus on noninvasive magnetic resonance spectroscopy (MRS) and spectroscopic imaging (MRSI) and their roles in future personalized medicine in cancer. Diagnosis, the identification of the most effective treatment, monitoring treatment delivery, and response to treatment are some of the broad areas into which MRS techniques can be integrated to improve treatment outcomes. The development of novel probes for molecular imaging—in combination with a slew of functional imaging capabilities—makes MRS techniques, especially in combination with other imaging modalities, valuable in cancer drug discovery and basic cancer research.

Glunde, Kristine; Bhujwalla, Zaver M.

2011-01-01

399

Imaging Conditioned Fear Circuitry Using Awake Rodent fMRI  

PubMed Central

Functional magnetic resonance imaging (fMRI) is a powerful method for exploring emotional and cognitive brain responses in humans. However rodent fMRI has not previously been applied to the analysis of learned behaviour in awake animals, limiting its use as a translational tool. Here we have developed a novel paradigm for studying brain activation in awake rats responding to conditioned stimuli using fMRI. Using this method we show activation of the amygdala and related fear circuitry in response to a fear-conditioned stimulus and demonstrate that the magnitude of fear circuitry activation is increased following early life stress, a rodent model of affective disorders. This technique provides a new translatable method for testing environmental, genetic and pharmacological manipulations on emotional and cognitive processes in awake rodent models.

Brydges, Nichola M.; Whalley, Heather C.; Jansen, Maurits A.; Merrifield, Gavin D.; Wood, Emma R.; Lawrie, Stephen M.; Wynne, Sara-Madge; Day, Mark; Fleetwood-Walker, Sue; Steele, Douglas; Marshall, Ian; Hall, Jeremy; Holmes, Megan C.

2013-01-01

400

Reciprocity and gyrotropism in magnetic resonance transduction  

NASA Astrophysics Data System (ADS)

We give formulas for transduction in magnetic resonance—i.e., the appearance of an emf due to Larmor precession of spins—based upon the modified Lorentz reciprocity principle for gyrotropic (also called “nonreciprocal”) media, i.e., in which a susceptibility tensor is carried to its transpose by reversal of an external static field [cf., R. F. Harrington and A. T. Villeneuve IRE Trans. Microwave Theory and Technique MTT6, 308 (1958)]. Prior applications of reciprocity to magnetic resonance, despite much success, have ignored the gyrotropism which necessarily arises due to nuclear and/or unpaired electronic spins. For detection with linearly polarized fields, oscillating at the Larmor frequency, the emf is written in terms of a volume integral containing a product of two factors which we define as the antenna patterns, i.e., (H1x±iH1y) , where, e.g., for a single transceive antenna, the H ’s are just the spatially dependent oscillatory magnetic field strengths, per the application of some reference current at the antenna terminals, with the negative sign obtaining for transmission, and the positive for reception. Similar expressions hold for separate transmit and receive antennas; expressions are also given for circular polarization of the fields. We then exhibit a receive-only array antenna of two elements for magnetic resonance imaging of protons, which, due an intensity artifact arising from stray reactive coupling of the elements, produces, despite its own bilateral symmetry, asymmetric proton NMR images of a symmetric cylindrical phantom containing aqueous saline solution [J. Tropp and T. Schirmer, J. Magn. Reson. 151, 146 (2001)]. Modification of this two-port antenna, to function in transmit-receive mode, allows us to demonstrate highly nonreciprocal behavior: that is, to record images (of cylindrical test phantoms containing aqueous saline solution) whose appearance dramatically changes, when the roles of transmission and reception are swapped between the two antenna ports—giving in one instance a signal intensity pattern whose form resembles an umbrella (i.e., with a central column of moderate intensity surmounted by a bright canopy), and in the other, a distorted oval with slight concavities at its horizontal extremes, whose outline suggests that of a cat’s eye. The relation between image patterns and drive scheme can be shown to reverse if the static polarizing field is reversed. Electromagnetic and circuit calculations, together with the modified reciprocity principle, allow us to reproduce these pattern changes in numerical simulations, closely and convincingly. Although the imaging experiments are performed at a static field of 3.0T , and consequently a Larmor frequency of 128MHz , the nonreciprocal effects are not related to the shortness of the wavelength in aqueous medium, but appear equally in simulations based in either the quasistatic or full electromagnetic regimes. Finally, we show that although antenna patterns for transmission and reception are swapped with reversal of the polarizing field, meaning that the receive pattern equals the transmit pattern with the field reversed, this in no way invalidates the familiar rotating wave model of spin dynamics in magnetic resonance.

Tropp, James

2006-12-01

401

Reciprocity and gyrotropism in magnetic resonance transduction  

SciTech Connect

We give formulas for transduction in magnetic resonance - i.e., the appearance of an emf due to Larmor precession of spins - based upon the modified Lorentz reciprocity principle for gyrotropic (also called 'nonreciprocal') media, i.e., in which a susceptibility tensor is carried to its transpose by reversal of an external static field [cf., R. F. Harrington and A. T. Villeneuve IRE Trans. Microwave Theory and Technique MTT6, 308 (1958)]. Prior applications of reciprocity to magnetic resonance, despite much success, have ignored the gyrotropism which necessarily arises due to nuclear and/or unpaired electronic spins. For detection with linearly polarized fields, oscillating at the Larmor frequency, the emf is written in terms of a volume integral containing a product of two factors which we define as the antenna patterns, i.e. (H{sub 1x}{+-}iH{sub 1y}), where, e.g., for a single transceive antenna, the H's are just the spatially dependent oscillatory magnetic field strengths, per the application of some reference current at the antenna terminals, with the negative sign obtaining for transmission, and the positive for reception. Similar expressions hold for separate transmit and receive antennas; expressions are also given for circular polarization of the fields. We then exhibit a receive-only array antenna of two elements for magnetic resonance imaging of protons, which, due an intensity artifact arising from stray reactive coupling of the elements, produces, despite its own bilateral symmetry, asymmetric proton NMR images of a symmetric cylindrical phantom containing aqueous saline solution [J. Tropp and T. Schirmer, J. Magn. Reson. 151, 146 (2001)]. Modification of this two-port antenna, to function in transmit-receive mode, allows us to demonstrate highly nonreciprocal behavior: that is, to record images (of cylindrical test phantoms containing aqueous saline solution) whose appearance dramatically changes, when the roles of transmission and reception are swapped between the two antenna ports--giving in one instance a signal intensity pattern whose form resembles an umbrella (i.e., with a central column of moderate intensity surmounted by a bright canopy), and in the other, a distorted oval with slight concavities at its horizontal extremes, whose outline suggests that of a cat's eye. The relation between image patterns and drive scheme can be shown to reverse if the static polarizing field is reversed. Electromagnetic and circuit calculations, together with the modified reciprocity principle, allow us to reproduce these pattern changes in numerical simulations, closely and convincingly. Although the imaging experiments are performed at a static field of 3.0 T, and consequently a Larmor frequency of 128 MHz, the nonreciprocal effects are not related to the shortness of the wavelength in aqueous medium, but appear equally in simulations based in either the quasistatic or full electromagnetic regimes. Finally, we show that although antenna patterns for transmission and reception are swapped with reversal of the polarizing field, meaning that the receive pattern equals the transmit pattern with the field reversed, this in no way invalidates the familiar rotating wave model of spin dynamics in magnetic resonance.

Tropp, James [General Electric Healthcare Technologies, 47697 Westinghouse Drive, Fremont, California 94539 (United States)

2006-12-15

402

Probing thalamic integrity in schizophrenia using concurrent transcranial magnetic stimulation and functional magnetic resonance imaging  

PubMed Central

Context Schizophrenia is a devastating illness with an indeterminate pathophysiology. Several lines of evidence implicate dysfunction in the thalamus, a key node in the distributed neural networks underlying perception, emotion, and cognition. Existing evidence of aberrant thalamic function is based on indirect measures of thalamic activity, but dysfunction has not yet been demonstrated with a causal method. Objective Test the hypothesis that direct physiological stimulation of cortex will produce an abnormal thalamic response in individuals with schizophrenia. Design We stimulated the precentral gyrus with single-pulse transcranial magnetic stimulation (spTMS) and measured the response to this pulse in synaptically-connected regions (thalamus, medial superior frontal cortex [mSFG], insula) using concurrent functional magnetic resonance imaging (fMRI). The mean hemodynamic response from these regions was fit with the sum of two gamma functions and response parameters were compared across groups. Setting Academic research laboratory. Participants Patients with schizophrenia and sex- and age- matched psychiatrically healthy subjects were recruited from the community. Main Outcome Measures Peak amplitude of the thalamic hemodynamic response to spTMS of precentral gyrus. Results spTMS-evoked responses did not differ between groups at the cortical stimulation site. Compared to healthy subjects, schizophrenia patients showed a reduced response to spTMS in the thalamus (P=1.86 × 10?9) and mSFG (P=.02). Similar results were observed in the insula. Sham TMS indicated that these results could not be attributed to indirect effects of TMS coil discharge. Functional connectivity analyses revealed weaker thalamus-mSFG and thalamus-insula connectivity in schizophrenia patients compared to control subjects. Conclusions Individuals with schizophrenia showed reduced thalamic activation in response to direct perturbation delivered to the cortex. These results extend prior work implicating the thalamus in the pathophysiology of schizophrenia and suggest that the thalamus contributes to the patterns of aberrant connectivity characteristic of this disease.

Guller, Yelena; Ferrarelli, Fabio; Shackman, Alexander J.; Sarasso, Simone; Peterson, Michael J.; Langheim, Frederick J.; Meyerand, Mary E.; Tononi, Giulio; Postle, Bradley R.

2012-01-01

403

BROADBAND EXCITATION IN NUCLEAR MAGNETIC RESONANCE  

SciTech Connect

Theoretical methods for designing sequences of radio frequency (rf) radiation pulses for broadband excitation of spin systems in nuclear magnetic resonance (NMR) are described. The sequences excite spins uniformly over large ranges of resonant frequencies arising from static magnetic field inhomogeneity, chemical shift differences, or spin couplings, or over large ranges of rf field amplitudes. Specific sequences for creating a population inversion or transverse magnetization are derived and demonstrated experimentally in liquid and solid state NMR. One approach to broadband excitation is based on principles of coherent averaging theory. A general formalism for deriving pulse sequences is given, along with computational methods for specific cases. This approach leads to sequences that produce strictly constant transformations of a spin system. The importance of this feature in NMR applications is discussed. A second approach to broadband excitation makes use of iterative schemes, i.e. sets of operations that are applied repetitively to a given initial pulse sequences, generating a series of increasingly complex sequences with increasingly desirable properties. A general mathematical framework for analyzing iterative schemes is developed. An iterative scheme is treated as a function that acts on a space of operators corresponding to the transformations produced by all possible pulse sequences. The fixed points of the function and the stability of the fixed points are shown to determine the essential behavior of the scheme. Iterative schemes for broadband population inversion are treated in detail. Algebraic and numerical methods for performing the mathematical analysis are presented. Two additional topics are treated. The first is the construction of sequences for uniform excitation of double-quantum coherence and for uniform polarization transfer over a range of spin couplings. Double-quantum excitation sequences are demonstrated in a liquid crystal system. The second additional topic is the construction of iterative schemes for narrowband population inversion. The use of sequences that invert spin populations only over a narrow range of rf field amplitudes to spatially localize NMR signals in an rf field gradient is discussed.

Tycko, R.

1984-10-01

404

Proton Magnetic Resonance Imaging of Flowing Blood.  

NASA Astrophysics Data System (ADS)

A novel technique of making angiographic images non-invasively by NMR is introduced. In order to visualize the vascular structure, flowing blood must be labeled to achieve contrast against background static tissue. In this technique, a little surface coil is used as the labeling device in addition to a whole-body NMR imager. To label the flowing blood, a magnetic field gradient is applied along the long axis of a living subject. The labeling coil over a carotid artery in the neck is fed RF at the resonant frequency of the protons under the coil. Arterial flow moves blood protons from a field below resonance (at the heart), steadily passing through resonance (at the neck) to a field high above resonance (in the head); at the end of the event blood protons are inverted, or labeled by an adiabatic fast passage. Meanwhile, protons in stationary tissue feel only a constant field and remain unaffected. Blood retains this label as it flows downstream into the head and gives a negative signal, while protons in other tissue a positive signal. Two projection images of the head, with and without labeling, are obtained and subtracted digitally. The residue of the subtraction shows moving material only since signals arising from static material are identical and are cancelled in the subtraction process. Finally, the three dimensional vascular structure is presented in a projective format onto a two dimensional plane resembling an angiogram produced with dye injection and X-rays. Pulse sequences specially designed to image moving objects are presented and discussed. Experimental results on phantoms, volunteers and patients are demonstrated. Competing techniques by NMR are reviewed and compared.

Du, Leila Ning-Zhi

1987-09-01

405

Functional magnetic resonance imaging of cognitive processing in young adults with Down syndrome.  

PubMed

The authors used functional magnetic resonance imaging (fMRI) to investigate neural activation during a semantic-classification/object-recognition task in 13 persons with Down syndrome and 12 typically developing control participants (age range ?=? 12-26 years). A comparison between groups suggested atypical patterns of brain activation for the individuals with Down syndrome. Correlation analyses between an index of visual spatial ability and brain activation depicted a positive relationship between (a) this index and brain activation in regions of the occipital and parietal lobes for the typically developing individuals and (b) the middle and dorsal frontal gyri in the individuals with Down syndrome. These findings supported the authors' hypothesis that persons with Down syndrome demonstrate atypical neural activation compared with typically developing individuals matched for chronological age. PMID:21905803

Jacola, Lisa M; Byars, Anna W; Chalfonte-Evans, Melinda; Schmithorst, Vincent J; Hickey, Fran; Patterson, Bonnie; Hotze, Stephanie; Vannest, Jennifer; Chiu, Chung-Yiu; Holland, Scott K; Schapiro, Mark B

2011-09-01

406

Lateralization of prefrontal activation during internal mental calculation: a functional magnetic resonance imaging study.  

PubMed

1. Functional magnetic resonance imaging (fMRI) at 1.5 T was used to investigate the lateralization of prefrontal cortex activity during internal mental calculation in 16 human volunteers (8 right-handed and 8 left-handed). Subjects were asked to perform two different tasks: 1) a serial subtraction of prime numbers and 2) a control task in which they mentally recited numbers. 2. Signal modifications were regularly observed in the prefrontal cortex (Brodmann's area 46) during the serial subtraction of prime numbers, whereas the number listing task poorly activated the same areas. 3. In right-handed subjects, activation was clearly lateralized in the left dorsolateral prefrontal cortex, whereas a frequent bilateral activation was found in left-handed subjects. 4. We conclude that prefrontal activation during mental calculation is lateralized in a manner similar to that reported during linguistic tasks, i.e., a clear lateralization in right- but not in left-handed subjects. PMID:8592209

Burbaud, P; Degreze, P; Lafon, P; Franconi, J M; Bouligand, B; Bioulac, B; Caille, J M; Allard, M

1995-11-01

407

Functional Magnetic Resonance Imaging Phase Synchronization as a Measure of Dynamic Functional Connectivity  

PubMed Central

Abstract Functional brain activity and connectivity have been studied by calculating intersubject and seed-based correlations of hemodynamic data acquired with functional magnetic resonance imaging (fMRI). To inspect temporal dynamics, these correlation measures have been calculated over sliding time windows with necessary restrictions on the length of the temporal window that compromises the temporal resolution. Here, we show that it is possible to increase temporal resolution by using instantaneous phase synchronization (PS) as a measure of dynamic (time-varying) functional connectivity. We applied PS on an fMRI dataset obtained while 12 healthy volunteers watched a feature film. Narrow frequency band (0.04–0.07?Hz) was used in the PS analysis to avoid artifactual results. We defined three metrics for computing time-varying functional connectivity and time-varying intersubject reliability based on estimation of instantaneous PS across the subjects: (1) seed-based PS, (2) intersubject PS, and (3) intersubject seed-based PS. Our findings show that these PS-based metrics yield results consistent with both seed-based correlation and intersubject correlation methods when inspected over the whole time series, but provide an important advantage of maximal single-TR temporal resolution. These metrics can be applied both in studies with complex naturalistic stimuli (e.g., watching a movie or listening to music in the MRI scanner) and more controlled (e.g., event-related or blocked design) paradigms. A MATLAB toolbox FUNPSY (http://becs.aalto.fi/bml/software.html) is openly available for using these metrics in fMRI data analysis.

Salmi, Juha; Lahnakoski, Juha M.; Jaaskelainen, Iiro P.; Sams, Mikko

2012-01-01

408

Epileptic Networks in Focal Cortical Dysplasia Revealed Using Electroencephalography-Functional Magnetic Resonance Imaging  

PubMed Central

Objective Surgical treatment of focal epilepsy in patients with focal cortical dysplasia (FCD) is most successful if all epileptogenic tissue is resected. This may not be evident on structural magnetic resonance imaging (MRI), so intracranial electroencephalography (icEEG) is needed to delineate the seizure onset zone (SOZ). EEG-functional MRI (fMRI) can reveal interictal discharge (IED)-related hemodynamic changes in the irritative zone (IZ). We assessed the value of EEG-fMRI in patients with FCD-associated focal epilepsy by examining the relationship between IED-related hemodynamic changes, icEEG findings, and postoperative outcome. Methods Twenty-three patients with FCD-associated focal epilepsy undergoing presurgical evaluation including icEEG underwent simultaneous EEG-fMRI at 3T. IED-related hemodynamic changes were modeled, and results were overlaid on coregistered T1-weighted MRI scans fused with computed tomography scans showing the intracranial electrodes. IED-related hemodynamic changes were compared with the SOZ on icEEG and postoperative outcome at 1 year. Results Twelve of 23 patients had IEDs during recording, and 11 of 12 had significant IED-related hemodynamic changes. The fMRI results were concordant with the SOZ in 5 of 11 patients, all of whom had a solitary SOZ on icEEG. Four of 5 had >50% reduction in seizure frequency following resective surgery. The remaining 6 of 11 patients had widespread or discordant regions of IED-related fMRI signal change. Five of 6 had either a poor surgical outcome (<50% reduction in seizure frequency) or widespread SOZ precluding surgery. Interpretation Comparison of EEG-fMRI with icEEG suggests that EEG-fMRI may provide useful additional information about the SOZ in FCD. Widely distributed discordant regions of IED-related hemodynamic change appear to be associated with a widespread SOZ and poor postsurgical outcome. ANN NEUROL 2011

Thornton, Rachel; Vulliemoz, Serge; Rodionov, Roman; Carmichael, David W; Chaudhary, Umair J; Diehl, Beate; Laufs, Helmut; Vollmar, Christian; McEvoy, Andrew W; Walker, Matthew C; Bartolomei, Fabrice; Guye, Maxime; Chauvel, Patrick; Duncan, John S; Lemieux, Louis

2011-01-01

409

Altered cortical and subcortical local coherence in obstructive sleep apnea: a functional magnetic resonance imaging study.  

PubMed

Obstructive sleep apnea (OSA) syndrome is the most common sleep-related breathing disorder, characterized by excessive snoring and repetitive apneas and arousals, which leads to fragmented sleep and, most importantly, to intermittent nocturnal hypoxaemia during apneas. Considering previous studies about morphovolumetric alterations in sleep apnea, in this study we aimed to investigate for the first time the functional connectivity profile of OSA patients and age-gender-matched healthy controls, using resting-state functional magnetic resonance imaging (fMRI). Twenty severe OSA patients (mean age 43.2 ± 8 years; mean apnea-hypopnea index, 36.3 h(-1) ) and 20 non-apneic age-gender-body mass index (BMI)-matched controls underwent fMRI and polysomnographic (PSG) registration, as well as mood and sleepiness evaluation. Cerebro-cerebellar regional homogeneity (ReHo) values were calculated from fMRI acquisition, in order to identify pathology-related alterations in the local coherence of low-frequency signal (<0.1 Hz). Multivariate pattern classification was also performed using ReHo values as features. We found a significant pattern of cortical and subcortical abnormal local connectivity in OSA patients, suggesting an overall rearrangement of hemispheric connectivity balance, with a decrease of local coherence observed in right temporal, parietal and frontal lobe regions. Moreover, an increase in bilateral thalamic and somatosensory/motor cortices coherence have been found, a finding due possibly to an aberrant adaptation to incomplete sleep-wake transitions during nocturnal apneic episodes, induced by repetitive choke sensation and physical efforts attempting to restore breathing. Different hemispheric roles into sleep processes and a possible thalamus key role in OSA neurophysiopathology are intriguing issues that future studies should attempt to clarify. PMID:23171248

Santarnecchi, Emiliano; Sicilia, Isabella; Richiardi, Jonas; Vatti, Giampaolo; Polizzotto, Nicola Riccardo; Marino, Daniela; Rocchi, Raffaele; Van De Ville, Dimitri; Rossi, Alessandro

2012-11-21

410

Multi-projection magnetic resonance inverse imaging of the human visuomotor system.  

PubMed

Using highly parallel radiofrequency (RF) detection, magnetic resonance inverse imaging (InI) can achieve 100 ms temporal resolution with whole brain coverage. This is achieved by trading off partition encoding steps and thus spatial resolution for a higher acquisition rate. The reduced spatial information is estimated by solving under-determined inverse problems using RF coil sensitivity information. Here we propose multi projection inverse imaging (mInI) to combine different projection images to improve the spatial resolution of InI. Specifically, coronal, sagittal, and transverse projection images were acquired from different runs of the fMRI acquisitions using a 32-channel head coil array. Simulations show that mInI improves the quality of the instantaneous image reconstruction significantly. Going from one projection to three projections, the spatial resolution quantified by the full width at half maximum of the point-spread function (PSF) is improved from 2.6 pixels to 1.4 pixels (4 mm nominal resolution per pixel). Considering the shape of the PSF, the effective spatial resolution is improved from 16.9 pixels to 4.7 pixels. In vivo fMRI experiments using a two-choice reaction time tasks show visual and sensorimotor cortical activities spatially consistent with typical EPI data, yet mInI offers 100 ms temporal resolution with the whole brain coverage. The mInI data with three projections revealed that the sensorimotor cortex was activated 700 ms after the visual cortex. mInI can be applied to BOLD-contrast fMRI experiments to characterize the dynamics of the activated brain areas with a high spatiotemporal resolution. PMID:22326985

Tsai, Kevin Wen-Kai; Nummenmaa, Aapo; Witzel, Thomas; Chang, Wei-Tang; Kuo, Wen-Jui; Lin, Fa-Hsuan

2012-02-04

411

Multi-projection magnetic resonance inverse imaging of the human visuomotor system  

PubMed Central

Using highly parallel radiofrequency (RF) detection, magnetic resonance inverse imaging (InI) can achieve 100 ms temporal resolution with whole brain coverage. This is achieved by trading off partition encoding steps and thus spatial resolution for a higher acquisition rate. The reduced spatial information is estimated by solving under-determined inverse problems using RF coil sensitivity information. Here we propose multi projection inverse imaging (mInI) to combine different projection images to improve the spatial resolution of InI. Specifically, coronal, sagittal, and transverse projection images were acquired from different runs of the fMRI acquisitions using a 32-channel head coil array. Simulations show that mInI improves the quality of the instantaneous image reconstruction significantly. Going from one projection to three projections, the spatial resolution quantified by the full width at half maximum of the point-spread function (PSF) is improved from 2.6 pixels to 1.4 pixels (4 mm nominal resolution per pixel). Considering the shape of the PSF, the effective spatial resolution is improved from 16.9 pixels to 4.7 pixels. In vivo fMRI experiments using a two-choice reaction time tasks shows visual and sensorimotor cortical activity spatially consistent with typical EPI data, yet mInI offers 100 ms temporal resolution with the whole brain coverage. The mInI data with three projections revealed that the sensorimotor cortex was activated 700 ms after the visual cortex. mInI can be applied to BOLD-contrast fMRI experiments to characterize the dynamics of the activated brain areas with a high spatiotemporal resolution.

Tsai, Kevin Wen-Kai; Nummenmaa, Aapo; Witzel, Thomas; Chang, Wei-Tang; Kuo, Wen-Jui; Lin, Fa-Hsuan

2012-01-01

412

Permanent Magnet Structure for a Nuclear Magnetic Resonance Imager for Medical Diagnostics.  

National Technical Information Service (NTIS)

The present invention relates to the utilization of magnetic fields established by means of permanent magnets for use in medical diagnosis, particularly of the human body or torsi. Whole-body nuclear magnetic resonance diagnostics has been available in th...

H. A. Leupold E. Potenziani

1987-01-01

413

A desktop magnetic resonance imaging system.  

PubMed

Modern magnetic resonance imaging (MRI) systems consist of several complex, high cost subsystems. The cost and complexity of these systems often makes them impractical for use as routine laboratory instruments, limiting their use to hospitals and dedicated laboratories. However, advances in the consumer electronics industry have led to the widespread availability of inexpensive radio-frequency integrated circuits with exceptional abilities. We have developed a small, low-cost MR system derived from these new components. When combined with inexpensive desktop magnets, this type of MR scanner has the promise of becoming standard laboratory equipment for both research and education. This paper describes the development of a prototype desktop MR scanner utilizing a 0.21 T permanent magnet with an imaging region of approximately 2 cm diameter. The system uses commercially available components where possible and is programmed in LabVIEW software. Results from 3D data sets of resolution phantoms and fixed, newborn mice demonstrate the capability of this system to obtain useful images from a system constructed for approximately $13,500. PMID:11755094

Wright, Steven M; Brown, David G; Porter, Jay R; Spence, David C; Esparza, Emilio; Cole, David C; Huson, F Russell

2002-01-01

414

Abnormal baseline brain activity in bipolar depression: a resting state functional magnetic resonance imaging study.  

PubMed

We examined resting state brain activity in the depressive phase of bipolar disorder (BD) by measuring the amplitude of low-frequency fluctuations (ALFF) in the functional magnetic resonance imaging (fMRI) signal. Unlike functional connectivity, the ALFF approach reflects local properties in specific regions and provides direct information about impaired foci. Groups of 26 patients with BD depression and 26 gender-, age-, and education-matched healthy subjects participated in fMRI scans. We examined group differences in ALFF findings as well as correlations between clinical measurements and ALFF in the regions showing significant group differences. Our results showed that patients with BD depression had significantly increased ALFF in the left insula, the right caudate nucleus, the temporal gyrus, the bilateral inferior frontal gyrus, and the posterior lobe of the cerebellum. They also had decreased ALFF in the left postcentral gyrus, the left parahippocampal gyrus, and the cerebellum. Moderate negative correlations were found between the Hamilton Depression Rating Scale score and ALFF in the left insular cortex in the patient group. These results support a model of BD that involves dysfunction in the prefrontal-limbic networks and associated striatal systems. We also demonstrated the feasibility of ALFF as a technique to investigate persistent cerebral dysfunction in BD. PMID:23017873

Liu, Chun-Hong; Li, Feng; Li, Su-Fang; Wang, Yong-Jun; Tie, Chang-Le; Wu, Hai-Yan; Zhou, Zhen; Zhang, Dan; Dong, Jie; Yang, Zhi; Wang, Chuan-Yue

2012-09-25

415

Antinociceptive activity of crotoxin in the central nervous system: A functional Magnetic Resonance Imaging study.  

PubMed

Crotoxin, the main neurotoxic component of the venom of South American rattlesnake (Crotalus durissus terrificus), is reported to have potent antinociceptive activity. Several authors have shown mainly in behavioral pain models that crotoxin induces antinociceptive effects, supposed to be mediated by actions on the central nervous system. The antinociceptive effects of crotoxin (45 ?g/kg ip) in rats were verified in this study by increased response latencies in a Hargreaves test and tail flick test. In addition, it was demonstrated that crotoxin does not lead to motor impairments during a rotarod test and open field test. The main objective, carried out by blood oxygen level dependent functional Magnetic Resonance Imaging (BOLD fMRI) in anesthetized rats, was to determine which specific brain structures are involved in these antinociceptive effects. Moreover, potential antihyperalgesic effects were investigated by inducing a local hyperalgesia on the left hind paw. Therefore, antinociceptive effects (right paw) and antihyperalgesic effects (left paw) of crotoxin were able to be differentiated. As a result, crotoxin exhibited dominant antihyperalgesic but also antinociceptive effects during pain stimulation. Reductions of BOLD signal already occurred in brain input structures but were most prominent in primary and secondary somatosensory cortices. In conclusion, BOLD fMRI in anesthetized rats proved to be a helpful tool in toxinology, particularly in unraveled mechanisms of modulating nociception in the central nervous system by (potential) analgesics like crotoxin. PMID:23916599

Wolz-Richter, S; Esser, K-H; Hess, A

2013-08-03

416

Voluntary selection of task sets revealed by functional magnetic resonance imaging.  

PubMed

In everyday life, we have to selectively adapt our behavior to different situations and tasks. In cognitive psychology, such adaptive behavior can be investigated with the task-switching paradigm. However, in contrast to everyday life, in experiments participants are unequivocally told which task to perform. The present functional magnetic resonance imaging (fMRI) study was set out to investigate processes that are relevant when participants can decide by their own which task to perform. The number of tasks to choose from was varied between a forced condition (no choice) and two voluntary selection conditions (two or three choices). We expected to find prolonged reaction times as well as higher activations within the midcingulate cortex for the choice conditions compared to the no-choice condition. The fMRI results revealed a significant activation difference for the choice conditions versus the no-choice condition. For the choice contrast, activation was found in the rostral cingulate zone (RCZ) as well as the superior parietal lobule and the posterior part of the intraparietal sulcus. These activations revealed no selection-specific difference between three and two choices. Finally, a post hoc analysis showed that the activation in the RCZ is not associated with higher task-dependent response conflict when participants can select a task set. Taken together, these findings indicate that distinct brain areas are involved in the voluntary selection of abstract task set information. PMID:16513004

Forstmann, Birte U; Brass, Marcel; Koch, Iring; von Cramon, D Yves

2006-03-01

417

Orbitofrontal cortical dysfunction in akinetic catatonia: a functional magnetic resonance imaging study during negative emotional stimulation.  

PubMed

Catatonia is a psychomotor syndrome characterized by concurrent emotional, behavioral, and motor anomalies. Pathophysiological mechanisms of psychomotor disturbances may be related to abnormal emotional-motor processing in prefrontal cortical networks. We therefore investigated prefrontal cortical activation and connectivity patterns during emotional-motor stimulation using functional magnetic resonance imaging (FMRI). We investigated 10 akinetic catatonic patients in a postacute state and compared them with 10 noncatatonic postacute psychiatric controls (age-, sex-, diagnosis-, and medication-matched) and 10 healthy controls. Positive and negative pictures from the International Affective Picture System were used for emotional stimulation. FMRI measurements covered the whole frontal lobe, activation signals in various frontal cortical regions were obtained, and functional connectivity between the different prefrontal cortical regions was investigated using structural equation modeling. Catatonic patients showed alterations in the orbitofrontal cortical activation pattern and in functional connectivity to the premotor cortex in negative and positive emotions compared to psychiatric and healthy controls. Catatonic behavioral and affective symptoms correlated significantly with orbitofrontal activity, whereas catatonic motor symptoms were rather related to medial prefrontal activity. It is concluded that catatonic symptoms may be closely related to dysfunction in the orbitofrontal cortex and consequent alteration in the prefrontal cortical network during emotional processing. Because we investigated postacute patients, orbitofrontal cortical alterations may be interpreted as a trait marker predisposing for development of catatonic syndrome in schizophrenic or affective psychosis. PMID:15279056

Northoff, Georg; Kötter, Rolf; Baumgart, Frank; Danos, Peter; Boeker, Heinz; Kaulisch, Thomas; Schlagenhauf, Florian; Walter, Henrik; Heinzel, Alexander; Witzel, Thomas; Bogerts, Bernhard

2004-01-01

418

Neurohemodynamic correlates of 'OM' chanting: A pilot functional magnetic resonance imaging study  

PubMed Central

Background: A sensation of vibration is experienced during audible ‘OM’ chanting. This has the potential for vagus nerve stimulation through its auricular branches and the effects on the brain thereof. The neurohemodynamic correlates of ‘OM’ chanting are yet to be explored. Materials and Methods: Using functional Magnetic Resonance Imaging (fMRI), the neurohemodynamic correlates of audible ‘OM’ chanting were examined in right-handed healthy volunteers (n=12; nine men). The ‘OM’ chanting condition was compared with pronunciation of “ssss” as well as a rest state. fMRI analysis was done using Statistical Parametric Mapping 5 (SPM5). Results: In this study, significant deactivation was observed bilaterally during ‘OM’ chanting in comparison to the resting brain state in bilateral orbitofrontal, anterior cingulate, parahippocampal gyri, thalami and hippocampi. The right amygdala too demonstrated significant deactivation. No significant activation was observed during ‘OM’ chanting. In contrast, neither activation nor deactivation occurred in these brain regions during the comparative task – namely the ‘ssss’ pronunciation condition. Conclusion: The neurohemodynamic correlates of ‘OM’ chanting indicate limbic deactivation. As similar observations have been recorded with vagus nerve stimulation treatment used in depression and epilepsy, the study findings argue for a potential role of this ‘OM’ chanting in clinical practice.

Kalyani, Bangalore G; Venkatasubramanian, Ganesan; Arasappa, Rashmi; Rao, Naren P; Kalmady, Sunil V; Behere, Rishikesh V; Rao, Hariprasad; Vasudev, Mandapati K; Gangadhar, Bangalore N

2011-01-01

419

The impact of denoising on independent component analysis of functional magnetic resonance imaging data.  

PubMed

Independent component analysis (ICA) is a suitable method for decomposing functional magnetic resonance imaging (fMRI) activity into spatially independent patterns. Practice has revealed that low-pass filtering prior to ICA may improve ICA results by reducing noise and possibly by increasing source smoothness, which may enhance source independence; however, it eliminates useful information in high frequency features and it amplifies low signal fluctuations leading to independence loss. On the other hand, high-pass filtering may increase the independence by preserving spatial information, but its denoising properties are weak. Thus, such filtering strategies did not lead to simultaneous enhancements in independence and noise reduction; therefore, band-pass filtering or more sophisticated filtering methods are expected to be more appropriate. We used advanced wavelet filtering procedures, such as wavelet-based methods relying upon hard and soft coefficient thresholding and non-stationary Gaussian modelling based on geometrical prior information, to denoise artificial and real fMRI data. We compared the performance of these methods with the performance of traditional Gaussian smoothing techniques. First, we demonstrated both analytically and empirically the consistent performance increase of spatial filtering prior to ICA using spatial correlation and statistical sensitivity as quality measures. Second, all filtering methods were computationally efficient. Finally, denoising using low-pass filters was needed to improve ICA, suggesting that noise reduction may have a more significant effect on the component independence than the preservation of information contained within high frequencies. PMID:23261654

Pignat, Jean Michel; Koval, Oleksiy; Van De Ville, Dimitri; Voloshynovskiy, Sviatoslav; Michel, Christoph; Pun, Thierry

2012-12-20

420

Brain activity associated with expectancy-enhanced placebo analgesia as measured by functional magnetic resonance imaging.  

PubMed

In this study, a well established expectancy manipulation model was combined with a novel placebo intervention, a validated sham acupuncture needle, to investigate the brain network involved in placebo analgesia. Sixteen subjects completed the experiment. We found that after placebo acupuncture treatment, subjective pain rating reduction (pre minus post) on the placebo-treated side was significantly greater than on the control side. When we calculated the contrast that subtracts the functional magnetic resonance imaging (fMRI) signal difference between post-treatment and pretreatment during pain application on placebo side from the same difference on control side [e.g., placebo (post - pre) - control (post - pre)], significant differences were observed in the bilateral rostral anterior cingulate cortex (rACC), lateral prefrontal cortex, right anterior insula, supramarginal gyrus, and left inferior parietal lobule. The simple regression (correlation) analysis between each subject's fMRI signal difference of post-treatment and pretreatment difference on placebo and control side and the corresponding subjective pain rating difference showed that significant negative correlation was observed in the bilateral lateral/orbital prefrontal cortex, rACC, cerebellum, right fusiform, parahippocampus, and pons. These results are different from a previous study that found decreased activity in pain-sensitive regions such as the thalamus, insula, and ACC when comparing the response to noxious stimuli applied to control and placebo cream-treated areas of the skin. Our results suggest that placebo analgesia may be configured through multiple brain pathways and mechanisms. PMID:16407533

Kong, Jian; Gollub, Randy L; Rosman, Ilana S; Webb, J Megan; Vangel, Mark G; Kirsch, Irving; Kaptchuk, Ted J

2006-01-11

421

Auditory orienting and inhibition of return in schizophrenia: A functional magnetic resonance imaging study  

PubMed Central

Patients with schizophrenia (SP) exhibit deficits in both attentional reorienting and inhibition of return (IOR) during visual tasks. However, it is currently unknown whether these deficits are supramodal in nature and how these deficits relate to other domains of cognitive dysfunction. In addition, the neuronal correlates of this pathological orienting response have not been investigated in either the visual or auditory modality. Therefore, thirty SP and 30 healthy controls (HC) were evaluated with an extensive clinical protocol and functional magnetic resonance imaging (fMRI) during an auditory cuing paradigm. SP exhibited both increased costs and delayed IOR during auditory orienting, suggesting a prolonged interval for attentional disengagement from cued locations. Moreover, a delay in the development of IOR was associated with cognitive deficits on formal neuropsychological testing in the domains of attention/inhibition and working memory. Event-related fMRI showed the characteristic activation of a frontoparietal network (invalid trials > valid trials), but there were no differences in functional activation between patients and HC during either attentional reorienting or IOR. Current results suggest that orienting deficits are supramodal in nature in SP, and are related to higher-order cognitive deficits that directly interfere with day-to-day functioning.

Abbott, Christopher C.; Merideth, Flannery; Ruhl, David; Yang, Zhen; Clark, Vincent P.; Calhoun, Vince D.; Hanlon, Faith M.; Mayer, Andrew R.

2011-01-01

422

A Functional Magnetic Resonance Imaging Predictor of Treatment Response to Venlafaxine in Generalized Anxiety Disorder  

PubMed Central

Background Functional magnetic resonance imaging (fMRI) holds promise as a noninvasive means of identifying neural responses that can be used to predict treatment response before beginning a drug trial. Imaging paradigms employing facial expressions as presented stimuli have been shown to activate the amygdala and anterior cingulate cortex (ACC). Here, we sought to determine whether pretreatment amygdala and rostral ACC (rACC) reactivity to facial expressions could predict treatment outcomes in patients with generalized anxiety disorder (GAD). Methods Fifteen subjects (12 female subjects) with GAD participated in an open-label venlafaxine treatment trial. Functional magnetic resonance imaging responses to facial expressions of emotion collected before subjects began treatment were compared with changes in anxiety following 8 weeks of venlafaxine administration. In addition, the magnitude of fMRI responses of subjects with GAD were compared with that of 15 control subjects (12 female subjects) who did not have GAD and did not receive venlafaxine treatment. Results The magnitude of treatment response was predicted by greater pretreatment reactivity to fearful faces in rACC and lesser reactivity in the amygdala. These individual differences in pretreatment rACC and amygdala reactivity within the GAD group were observed despite the fact that 1) the overall magnitude of pretreatment rACC and amygdala reactivity did not differ between subjects with GAD and control subjects and 2) there was no main effect of treatment on rACC-amygdala reactivity in the GAD group. Conclusions These findings show that this pattern of rACC-amygdala responsivity could prove useful as a predictor of venlafaxine treatment response in patients with GAD.

Johnstone, Tom; Somerville, Leah H.; Nitschke, Jack B.; Polis, Sara; Alexander, Andrew L.; Davidson, Richard J.; Kalin, Ned H.

2008-01-01

423

Gender Differences in the Cognitive Control of Emotion: An fMRI Study  

ERIC Educational Resources Information Center

|The interaction of emotion and cognition has become a topic of major interest. However, the influence of gender on the interplay between the two processes, along with its neural correlates have not been fully analysed so far. In this functional magnetic resonance imaging (fMRI) study we induced negative emotion using negative olfactory…

Koch, Kathrin; Pauly, Katharina; Kellermann, Thilo; Seiferth, Nina Y.; Reske, Martina; Backes, Volker; Stocker, Tony; Shah, N. Jon; Amunts, Katrin; Kircher, Tilo; Schneider, Frank; Habel, Ute

2007-01-01

424

Dual-Tasking Alleviated Sleep Deprivation Disruption in Visuomotor Tracking: An fMRI Study  

ERIC Educational Resources Information Center

|Effects of dual-responding on tracking performance after 49-h of sleep deprivation (SD) were evaluated behaviorally and with functional magnetic resonance imaging (fMRI). Continuous visuomotor tracking was performed simultaneously with an intermittent color-matching visual detection task in which a pair of color-matched stimuli constituted a…

Gazes, Yunglin; Rakitin, Brian C.; Steffener, Jason; Habeck, Christian; Butterfield, Brady; Basner, Robert C.; Ghez, Claude; Stern, Yaakov

2012-01-01

425

Neural Changes after Phonological Treatment for Anomia: An fMRI Study  

ERIC Educational Resources Information Center

|Functional magnetic resonance imaging (fMRI) was used to investigate the neural processing characteristics associated with word retrieval abilities after a phonologically-based treatment for anomia in two stroke patients with aphasia. Neural activity associated with a phonological and a semantic task was compared before and after treatment with…

Rochon, Elizabeth; Leonard, Carol; Burianova, Hana; Laird, Laura; Soros, Peter; Graham, Simon; Grady, Cheryl

2010-01-01

426

Perceiving Age and Gender in Unfamiliar Faces: An fMRI Study on Face Categorization  

ERIC Educational Resources Information Center

|Efficient processing of unfamiliar faces typically involves their categorization (e.g., into old vs. young or male vs. female). However, age and gender categorization may pose different perceptual demands. In the present study, we employed functional magnetic resonance imaging (fMRI) to compare the activity evoked during age vs. gender…

Wiese, Holger; Kloth, Nadine; Gullmar, Daniel; Reichenbach, Jurgen R.; Schweinberger, Stefan R.

2012-01-01

427

Are Errors Differentiable from Deceptive Responses when Feigning Memory Impairment? An fMRI Study  

ERIC Educational Resources Information Center

|Previous neuroimaging studies have suggested that the neural activity associated with truthful recall, with false memory, and with feigned memory impairment are different from one another. Here, we report a functional magnetic resonance imaging (fMRI) study that addressed an important but yet unanswered question: Is the neural activity associated…

Lee, Tatia M. C.; Au, Ricky K. C.; Liu, Ho-Ling; Ting, K. H.; Huang, Chih-Mao; Chan, Chetwyn C. H.

2009-01-01

428

Auditory Verb Perception Recruits Motor Systems in the Developing Brain: An fMRI Investigation  

ERIC Educational Resources Information Center

|This study investigated neural activation patterns during verb processing in children, using fMRI (functional Magnetic Resonance Imaging). Preschool children (aged 4-6) passively listened to lists of verbs and adjectives while neural activation was measured. Findings indicated that verbs were processed differently than adjectives, as the verbs…

James, Karin Harman; Maouene, Josita

2009-01-01

429

Disconnected brains: What is the role of fMRI in connectivity research?  

Microsoft Academic Search

In this paper we consider how functional Magnetic Resonance Imaging (fMRI) has been used to study cortical connectivity in autism and autistic spectrum disorders (ASD). We discuss those studies that have contributed to the evidence supporting a model of disordered cortical connectivity in autism and (ASD), with a focusing emphasis on the application to research into the underconnectivity model. We

Ngoc Jade Thai; Olivia Longe; Gina Rippon

2009-01-01

430

Functional abnormalities in symptomatic concussed athletes: an fMRI study  

Microsoft Academic Search

Our aim was to quantify with functional magnetic resonance imaging (fMRI) changes in brain activity in concussed athletes and compare the results with those of normal control subjects. Regional brain activations associated with a working memory task were obtained from a group of concussed athletes (15 symptomatic, 1 asymptomatic) and eight matched control subjects, using blood oxygen level dependent (BOLD)

J.-K Chen; K. M Johnston; S Frey; M Petrides; K Worsley; A Ptito

2004-01-01

431

Somatotopic Representation of Nociceptive Information in the Putamen: An Event-related fMRI Study  

Microsoft Academic Search

The ability to locate pain plays a pivotal role in immediate defence and withdrawal behaviour. However, it is unclear to what extent nociceptive information is relayed to and processed in subcortical structures relevant for motor preparation and possibly the generation of withdrawal behaviour. We used single-trial functional magnetic resonance imaging (fMRI) to assess whether nociceptive information is represented in the

U. Bingel; J. Gläscher; C. Weiller; C. Büchel

2004-01-01

432

Hemispheric Lateralization Effects of Rhythm Implementation during Syllable Repetitions: An fMRI Study  

Microsoft Academic Search

Rhythm in terms of the modulation of syllable durations represents an information-bearing feature of verbal utterances contributing both to the meaning of a sentence (linguistic prosody) as well as a speaker's emotional expression (affective prosody). In order to delineate the neural structures subserving rhythmic shaping of speech production, functional magnetic resonance imaging (fMRI) was performed during (a) isochronous syllable repetitions

Axel Riecker; Dirk Wildgruber; Grzegorz Dogil; Wolfgang Grodd; Hermann Ackermann

2002-01-01

433

Voxel selection in fMRI data analysis: A sparse representation method  

Microsoft Academic Search

This paper proposes an iterative sparse representation-based algorithm for voxel selection in functional magnetic resonance imaging (fMRI) data. The output of the algorithm is a sparse weight vector, of which the magnitude of each entry represents the significance of its corresponding voxel with respect to mental tasks or stimulus. To demonstrate the validity of our algorithm and illustrate its application,

Yuanqing Li; Zhuliang Yu; Praneeth Namburi; Cuntai Guan

2009-01-01

434

The Neural Bases of Sentence Comprehension: a fMRI Examination of Syntactic and Lexical Processing  

Microsoft Academic Search

One of the challenges to functional neuroimaging is to understand how the component processes of reading comprehension emerge from the neural activity in a network of brain regions. In this study, functional magnetic resonance imaging (fMRI) was used to examine lexical and syntactic processing in reading comprehension by independently manipulating the cognitive demand on each of the two processes of

Timothy A. Keller; Patricia A. Carpenter; Marcel Adam Just

2001-01-01

435

What Has fMRI Told Us about the Development of Cognitive Control through Adolescence?  

ERIC Educational Resources Information Center

|Cognitive control, the ability to voluntarily guide our behavior, continues to improve throughout adolescence. Below we review the literature on age-related changes in brain function related to response inhibition and working memory, which support cognitive control. Findings from studies using functional magnetic resonance imaging (fMRI) indicate…

Luna, Beatriz; Padmanabhan, Aarthi; O'Hearn, Kirsten

2010-01-01

436

Auditory Verb Perception Recruits Motor Systems in the Developing Brain: An fMRI Investigation  

ERIC Educational Resources Information Center

This study investigated neural activation patterns during verb processing in children, using fMRI (functional Magnetic Resonance Imaging). Preschool children (aged 4-6) passively listened to lists of verbs and adjectives while neural activation was measured. Findings indicated that verbs were processed differently than adjectives, as the verbs…

James, Karin Harman; Maouene, Josita

2009-01-01

437

How Verbal and Spatial Manipulation Networks Contribute to Calculation: An fMRI Study  

ERIC Educational Resources Information Center

The manipulation of numbers required during calculation is known to rely on working memory (WM) resources. Here, we investigated the respective contributions of verbal and/or spatial WM manipulation brain networks during the addition of four numbers performed by adults, using functional magnetic resonance imaging (fMRI). Both manipulation and…

Zago, Laure; Petit, Laurent; Turbelin, Marie-Renee; Andersson, Frederic; Vigneau, Mathieu; Tzourio-Mazoyer, Nathalie

2008-01-01

438

Differences in Processing of Taxonomic and Sequential Relations in Semantic Memory: An fMRI Investigation  

ERIC Educational Resources Information Center

Conceptual knowledge of our world is represented in semantic memory in terms of concepts and semantic relations between concepts. We used functional magnetic resonance imaging (fMRI) to examine the cortical regions underlying the processing of sequential and taxonomic relations. Participants were presented verbal cues and performed three tasks:…

Kuchinke, Lars; van der Meer, Elke; Krueger, Frank

2009-01-01

439

fMRI Study of Cognitive Interference Processing in Females with Fragile X Syndrome  

Microsoft Academic Search

Females with fragile X syndrome, the most common form of inherited developmental and learning problems, are known to be impaired in executive function. The current study is the first to investigate the performance of females with fragile X on a cognitive interference task utilizing functional magnetic resonance imaging (fMRI). Fourteen females with fragile X and 14 age-matched healthy controls were

Leanne Tamm; Vinod Menon; Cindy K. Johnston; David R. Hessl; Allan L. Reiss

2002-01-01

440

Left superior parietal cortex involvement in writing: integrating fMRI with lesion evidence  

Microsoft Academic Search

Writing is a uniquely human skill that we utilize nearly everyday. Lesion studies in patients with Gerstmann’s syndrome have pointed to the parietal cortex as being critical for writing. Very little information is, however, available about the precise anatomical location of brain regions subserving writing in normal healthy individuals. In this study, we used functional magnetic resonance imaging (fMRI) to

V Menon; J. E Desmond

2001-01-01

441

Neuroanatomical Distribution of Five Semantic Components of Verbs: Evidence from fMRI  

ERIC Educational Resources Information Center

The Simulation Framework, also known as the Embodied Cognition Framework, maintains that conceptual knowledge is grounded in sensorimotor systems. To test several predictions that this theory makes about the neural substrates of verb meanings, we used functional magnetic resonance imaging (fMRI) to scan subjects' brains while they made semantic…

Kemmerer, David; Castillo, Javier Gonzalez; Talavage, Thomas; Patterson, Stephanie; Wiley, Cynthia

2008-01-01

442

Brain correlates of hypnotic paralysis—a resting-state fMRI study  

Microsoft Academic Search

Hypnotic paralysis has been used since the times of Charcot to study altered states of consciousness; however, the underlying neurobiological correlates are poorly understood. We investigated human brain function during hypnotic paralysis using resting-state functional magnetic resonance imaging (fMRI), focussing on two core regions of the default mode network and the representation of the paralysed hand in the primary motor

M. Pyka; M. Burgmer; T. Lenzen; R. Pioch; U. Dannlowski; B. Pfleiderer; A. W. Ewert; G. Heuft; V. Arolt; C. Konrad

2011-01-01

443

Neuroanatomical Distribution of Five Semantic Components of Verbs: Evidence from fMRI  

ERIC Educational Resources Information Center

|The Simulation Framework, also known as the Embodied Cognition Framework, maintains that conceptual knowledge is grounded in sensorimotor systems. To test several predictions that this theory makes about the neural substrates of verb meanings, we used functional magnetic resonance imaging (fMRI) to scan subjects' brains while they made semantic…

Kemmerer, David; Castillo, Javier Gonzalez; Talavage, Thomas; Patterson, Stephanie; Wiley, Cynthia

2008-01-01

444

Changes in fMRI Following Cognitive Rehabilitation in Severe Traumatic Brain Injury: A Case Study  

Microsoft Academic Search

Objective: To illustrate the relationship between changes in neuropsychological testing and changes in functional magnetic resonance imaging (fMRI) before and after cognitive rehabilitation therapy (CRT). Study Design: Single case study. Setting: Outpatient treatment center. Participant: A woman with history of severe traumatic brain injury (TBI) 16 years before study. Intervention: Individualized CRT using a developmental metacognitive model. Main Outcome Measures:

Linda Laatsch; Deborah Little; Keith Thulborn

2004-01-01

445

An fMRI investigation of the impact of interracial contact on executive function  

Microsoft Academic Search

We investigated whether individual differences in racial bias among white participants predict the recruitment, and potential depletion, of executive attentional resources during contact with black individuals. White individuals completed an unobtrusive measure of racial bias, then interacted with a black individual, and finally completed an ostensibly unrelated Stroop color-naming test. In a separate functional magnetic resonance imaging (fMRI) session, subjects

Abigail A Baird; Heather L Gordon; Todd F Heatherton; Carrie L Wyland; Sophie Trawalter; J Nicole Shelton; Jennifer A Richeson

2003-01-01

446

Deficient prefrontal attentional control in late-life generalized anxiety disorder: an fMRI investigation  

Microsoft Academic Search

Younger adults with anxiety disorders are known to show an attentional bias toward negative information. Little is known regarding the role of biased attention in anxious older adults, and even less is known about the neural substrates of any such bias. Functional magnetic resonance imaging (fMRI) was used to assess the mechanisms of attentional bias in late life by contrasting

R B Price; D A Eldreth; J Mohlman

2011-01-01

447

On the nature of the BOLD fMRI contrast mechanism  

Microsoft Academic Search

Since its development about 15 years ago, functional magnetic resonance imaging (fMRI) has become the leading research tool for mapping brain activity. The technique works by detecting the levels of oxygen in the blood, point by point, throughout the brain. In other words, it relies on a surrogate signal, resulting from changes in oxygenation, blood volume and flow, and does

Nikos K. Logothetis; Josef Pfeuffer

2004-01-01

448

Measuring Attachment Representation in an fMRI Environment: A Pilot Study  

Microsoft Academic Search

This exploratory study is the first to examine the neural correlates of attachment status in adults. The study examined the feasibility of assessing attachment narratives in the functional magnetic resonance imaging (fMRI) environment by challenging subjects to tell attachment stories to specific attachment pictures from the Adult Attachment Projective (AAP) while being scanned. We investigated theoretically derived hypotheses regarding predicted

Anna Buchheim; Susanne Erk; Carol George; Horst Kächele; Martin Ruchsow; Manfred Spitzer; Tilo Kircher; Henrik Walter

2006-01-01

449

FMRI of two measures of phonological processing in visual word recognition: Ecological validity matters  

Microsoft Academic Search

Previous functional magnetic resonance imaging (fMRI) studies have investigated the role of phonological processing by utilizing nonword rhyming decision tasks (e.g., Pugh et al., 1996). Although such tasks clearly engage phonological components of visual word recognition, it is clear that decision tasks are more cognitively involved than the simple overt naming tasks, which more closely map onto normal reading behavior.

William J. Owen; Ron Borowsky; Gordon E. Sarty

2004-01-01

450

Becoming a pianist. An fMRI study of musical literacy acquisition.  

PubMed

Musically naïve subjects were scanned using functional magnetic resonance imaging (fMRI) before and after they had been taught to read music and play keyboard. When subjects played melodies from musical notation after training, activation was seen in a cluster of voxels within the right superior parietal cortex consistent with the view that music reading involves spatial sensorimotor mapping. PMID:14681142

Stewart, Lauren; Henson, Rik; Kampe, Knut; Walsh, Vincent; Turner, Robert; Frith, Uta

2003-11-01

451

Detection of deception with fMRI: Are we there yet?  

Microsoft Academic Search

A decade of spectacular progress in functional magnetic resonance imaging (fMRI) technology and systems neuroscience research has so far yielded few changes in our daily lives. The dearth of clinical applications of this prolific and academically promising research tool began raising the eyebrows of the public and the research funding agencies. This may be one of the reasons for the

Daniel D. Langleben

2008-01-01

452

Seeing Chinese Characters in Action: An fMRI Study of the Perception of Writing Sequences  

ERIC Educational Resources Information Center

The Chinese character is composed of a finite set of strokes whose order in writing follows consensual principles and is learnt through school education. Using functional magnetic resonance imaging (fMRI), this study investigates the neural activity associated with the perception of writing sequences by asking participants to observe…

Yu, Hongbo; Gong, Lanyun; Qiu, Yinchen; Zhou, Xiaolin

2011-01-01

453

fMRI of alcohol craving after individual cues: A follow-up case report  

Microsoft Academic Search

Alcohol addiction is typically associated with intense alcohol craving triggered by internal or environmental cues linked with past alcohol use. We used functional magnetic resonance imaging (fMRI) to record cerebral correlates of craving in an alcoholic patient. Craving was evoked by highly individual cues associated with past alcohol use and was assessed before (T1) and after an 8-month period of

Stephanie Kunz; Thomas Beblo; Martin Driessen; Friedrich Woermann

2008-01-01

454

Enhancing equation comprehension with index finger writing: An fMRI study  

Microsoft Academic Search

Learning is a complicated process composed of vision, interpretation, comprehension and memory. This study for the first time compared activities in the brain for equation reading and writing by selected professionals using functional magnetic resonance imaging (fMRI). Finger writing did not change the message pathway in brain, but on the other hand intensified stimuli on the information integration and language

Xiao-Dong Wang; Ming-Tung Wang; Duu-Jong Lee

2008-01-01

455

Seeing Chinese Characters in Action: An fMRI Study of the Perception of Writing Sequences  

ERIC Educational Resources Information Center

|The Chinese character is composed of a finite set of strokes whose order in writing follows consensual principles and is learnt through school education. Using functional magnetic resonance imaging (fMRI), this study investigates the neural activity associated with the perception of writing sequences by asking participants to observe…

Yu, Hongbo; Gong, Lanyun; Qiu, Yinchen; Zhou, Xiaolin

2011-01-01

456

Abstinent adolescent marijuana users show altered fMRI response during spatial working memory  

Microsoft Academic Search

Marijuana is the most widely used illicit substance among teenagers, yet little is known about the possible neural influence of heavy marijuana use during adolescence. We previously demonstrated an altered functional magnetic resonance imaging (fMRI) activity related to spatial working memory (SWM) among adolescents who were heavy users of after an average of 8 days of abstinence, but the persisting

Alecia D. Schweinsburg; Bonnie J. Nagel; Brian C. Schweinsburg; Ann Park; Rebecca J. Theilmann; Susan F. Tapert

2008-01-01

457

Abstract Grammatical Processing of Nouns and Verbs in Broca's Area: Evidence from FMRI  

Microsoft Academic Search

The role of Broca's area in grammatical computation is unclear, because syntactic processing is often confounded with working memory, articulation, or semantic selection. Morphological processing potentially circumvents these problems. Using event-related functional magnetic resonance imaging (fMRI), we had 18 subjects silently inflect words or read them verbatim. Subtracting the activity pattern for reading from that for inflection, which indexes processes

Ned T. Sahin

2006-01-01

458

Brain activity underlying emotional valence and arousal: A response-related fMRI study  

Microsoft Academic Search

Emotional behavior is organized along two psychophysiologic dimensions: (1) valence, varying from negative to positive, and (2) arousal, varying from low to high. Behavioral responses along these dimensions are assumed to be mediated by different brain circuits. We recorded startle reflex modulation and skin conductance responses in healthy volunteers during functional magnetic resonance imaging (fMRI) while they viewed a set

Silke Anders; Martin Lotze; Michael Erb; Wolfgang Grodd; Niels Birbaumer

2004-01-01

459

Identifying neural components of emotion in free conversation with fMRI  

Microsoft Academic Search

To evaluate neural components of emotional utterance, functional Magnetic Resonance Imaging (fMRI) was operated during free conversation. Timing and types of emotional elements such as anger, sorrow, joy, excitement and calmness were identified by the Voice Emotion Analysis (VEA) system. Conducting the modified event-related analysis, we found increased Blood Oxygen Level Dependent (BOLD) activities during free conversation in the lateral

Shunji Mitsuyoshi; Fumiaki Monnma; Yasuto Tanaka; Tetsuto Minami; Makoto Kato; Tsutomu Murata

2011-01-01

460

How Verbal and Spatial Manipulation Networks Contribute to Calculation: An fMRI Study  

ERIC Educational Resources Information Center

|The manipulation of numbers required during calculation is known to rely on working memory (WM) resources. Here, we investigated the respective contributions of verbal and/or spatial WM manipulation brain networks during the addition of four numbers performed by adults, using functional magnetic resonance imaging (fMRI). Both manipulation and…

Zago, Laure; Petit, Laurent; Turbelin, Marie-Renee; Andersson, Frederic; Vigneau, Mathieu; Tzourio-Mazoyer, Nathalie

2008-01-01

461

Review articles Complementary aspects of diffusion imaging and fMRI; I: structure and function  

Microsoft Academic Search

Studying the intersection of brain structure and function is an important aspect of modern neuroscience. The development of magnetic resonance imaging (MRI) over the last 25 years has provided new and powerful tools for the study of brain structure and function. Two tools in particular, diffusion imaging and functional MRI (fMRI), are playing increasingly important roles in elucidating the complementary

Robert V. Mulkern; Peter E. Davis; Steven J. Haker; Raul San Jose Estepar; Lawrence P. Panych; Stephan E. Maier; Michael J. Rivkin

462

Language Switching and Language Representation in Spanish–English Bilinguals: An fMRI Study  

Microsoft Academic Search

The current experiment was designed to investigate the nature of cognitive control in within- and between-language switching in bilingual participants. To examine the neural substrate of language switching we used functional magnetic resonance imaging (fMRI) as subjects named pictures in one language only or switched between languages. Participants were als