Sample records for magnetic resonance fmri

  1. The physics of functional magnetic resonance imaging (fMRI)

    NASA Astrophysics Data System (ADS)

    Buxton, Richard B.

    2013-09-01

    Functional magnetic resonance imaging (fMRI) is a methodology for detecting dynamic patterns of activity in the working human brain. Although the initial discoveries that led to fMRI are only about 20 years old, this new field has revolutionized the study of brain function. The ability to detect changes in brain activity has a biophysical basis in the magnetic properties of deoxyhemoglobin, and a physiological basis in the way blood flow increases more than oxygen metabolism when local neural activity increases. These effects translate to a subtle increase in the local magnetic resonance signal, the blood oxygenation level dependent (BOLD) effect, when neural activity increases. With current techniques, this pattern of activation can be measured with resolution approaching 1 mm3 spatially and 1 s temporally. This review focuses on the physical basis of the BOLD effect, the imaging methods used to measure it, the possible origins of the physiological effects that produce a mismatch of blood flow and oxygen metabolism during neural activation, and the mathematical models that have been developed to understand the measured signals. An overarching theme is the growing field of quantitative fMRI, in which other MRI methods are combined with BOLD methods and analyzed within a theoretical modeling framework to derive quantitative estimates of oxygen metabolism and other physiological variables. That goal is the current challenge for fMRI: to move fMRI from a mapping tool to a quantitative probe of brain physiology.

  2. Functional magnetic resonance imaging (fMRI) \\

    Microsoft Academic Search

    David D. Cox; Robert L. Savoy

    Traditional (univariate) analysis of functional MRI (fMRI) data relies exclusively on the information contained in the time course of individual voxels. Multivariate analyses can take advantage of the information contained in activity patterns across space, from multiple voxels. Such analyses have the potential to greatly expand the amount of information extracted from fMRI data sets. In the present study, multivariate

  3. Application of independent component analysis for activation detection in functional magnetic resonance imaging (FMRI) data

    Microsoft Academic Search

    Mahsa Akhbari; Emad Fatemizadeh

    2009-01-01

    In this extended summary, our aim is analyzing functional magnetic resonance imaging (fMRI) data by independent component analysis (ICA) in order to find regions of brain which were activated by neural activity in human brain. We employ the minimum description length (MDL) criterion to reduce the dimension of the data and estimate the number of components, which makes ICA work

  4. Functional Magnetic Resonance Imaging (fMRI) with Auditory Stimulation in Songbirds

    PubMed Central

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

    2013-01-01

    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

  5. Self-regulation of local brain activity using real-time functional magnetic resonance imaging (fMRI)

    Microsoft Academic Search

    Nikolaus Weiskopf; Frank Scharnowski; Ralf Veit; Rainer Goebel; Niels Birbaumer; Klaus Mathiak

    2005-01-01

    Functional magnetic resonance imaging (fMRI) measures the blood oxygen level-dependent (BOLD) signal related to neuronal activ- ity. So far, this technique has been limited by time-consuming data analysis impeding on-line analysis. In particular, no brain-computer interface (BCI) was available which provided on-line feedback to learn physiological self-regulation of the BOLD signal. Recently, stud- ies have shown that fMRI feedback is

  6. Nonlinearities in the blood-oxygenation-level dependent (BOLD) response measured by functional magnetic resonance imaging (fMRI)

    Microsoft Academic Search

    S. A. Huettel

    2004-01-01

    A central question in the analysis of functional magnetic resonance imaging (IMRI) data is whether the measured fMRI signal summates in a linear fashion over repeated inputs. Most fMRI studies collect images sensitive to blood-oxygenation-level dependent (BOLD) contrast, which measures the local amount of deoxygenated hemoglobin (dHb). When neurons are active, more oxygenated hemoglobin is supplied than is needed for

  7. Functional Magnetic Resonance Imaging (fMRI): A Brief Exercise for an Undergraduate Laboratory Course.

    PubMed

    Hurd, Mark W; Vincent, Diana J

    2006-01-01

    Functional neuroimaging represents an important technique for the study of the brain. However, the skills necessary for collecting, processing, and analyzing functional magnetic resonance imaging (fMRI) data sets are complex and relatively few undergraduate programs offer students an opportunity to acquire these skills or to observe functional neuroimaging. We report here on our experiences working with functional neuroimaging in an undergraduate laboratory course and suggest resources for the implementation of a similar exercise in a comparable setting. This exercise is structured so that four class meetings are devoted to functional neuroimaging. During these sessions, we discuss the basics of fMRI, study design, the advantages and disadvantages of this technique for the study of brain function as well as a general overview of data processing and analysis. Due to the college's proximity to a medical school, we are able to offer students an opportunity to observe functional neuroimaging sessions (however, this component is not critical for the completion of this exercise). Two final class sessions are devoted to data processing and presentation as well as writing up the experimental results. The exercise culminates in a paper based on the American Psychological Association format for a small number of subjects. At the conclusion of the exercise, students were surveyed to assess their impressions of the lab sessions. The results from these surveys indicate that students found this portion of the laboratory course to be a very positive experience. While this lab exercise does require some initial set up, we believe it stimulates the development of critical thinking skills with a technique that is used increasingly in neuroscience research. Both print and online resources are suggested to assist faculty in setting up a similar exercise. PMID:23493760

  8. High-field 4.23 tesla magnetic resonance imaging: initial experience in turbo-inversion recovery imaging and fMRI physics

    Microsoft Academic Search

    Rakesh Sharma

    2004-01-01

    High-field magnetic resonance imaging (MRI) offers functional, biochemical and physiological information. High field is advantageous for both fMRI signal generated from deoxyhemoglobin and blood oxygen, and intracellular sodium by inversion recovery MRI imaging. High field MRI was used to image human and primates for sodium MRI imaging.

  9. The lie of fMRI: an examination of the ethics of a market in lie detection using functional magnetic resonance imaging.

    PubMed

    White, Amy E

    2010-09-01

    In this paper, I argue that companies who use functional Magnetic Resonance Imaging (fMRI) scans for lie detection encounter the same basic ethical stumbling blocks as commercial companies that market traditional polygraphs. Markets in traditional voluntary polygraphs are common and fail to elicit much uproar among ethicists. Thus, for consistency, if markets in polygraphs are ethically unproblematic, markets using fMRIs for lie detection are equally as acceptable. Furthermore, while I acknowledge two substantial differences between the ethical concerns involving polygraphs and fMRI lie detection, I argue that these concerns can be overcome and do not lead to the conclusion that markets in fMRI lie detection are ethically dubious. It is my conclusion that voluntary markets in fMRI lie detection can be justified by consumer autonomy and should be allowed to persist. PMID:20730595

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

    PubMed

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

    2011-10-01

    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. PMID:21756946

  11. The Lie of fMRI: An Examination of the Ethics of a Market in Lie Detection Using Functional Magnetic Resonance Imaging

    Microsoft Academic Search

    Amy E. White

    2010-01-01

    In this paper, I argue that companies who use functional Magnetic Resonance Imaging (fMRI) scans for lie detection encounter\\u000a the same basic ethical stumbling blocks as commercial companies that market traditional polygraphs. Markets in traditional\\u000a voluntary polygraphs are common and fail to elicit much uproar among ethicists. Thus, for consistency, if markets in polygraphs\\u000a are ethically unproblematic, markets using fMRIs

  12. Functional magnetic resonance imaging (fMRI) of attention processes in presumed obligate carriers of schizophrenia: preliminary findings

    PubMed Central

    Filbey, Francesca Mapua; Russell, Tamara; Morris, Robin G; Murray, Robin M; McDonald, Colm

    2008-01-01

    Background Presumed obligate carriers (POCs) are the first-degree relatives of people with schizophrenia who, although do not exhibit the disorder, are in direct lineage of it. Thus, this subpopulation of first-degree relatives could provide very important information with regard to the investigation of endophenotypes for schizophrenia that could clarify the often contradictory findings in schizophrenia high-risk populations. To date, despite the extant literature on schizophrenia endophenotypes, we are only aware of one other study that examined the neural mechanisms that underlie cognitive abnormalities in this group. The aim of this study was to investigate whether a more homogeneous group of relatives, such as POCs, have neural abnormalities that may be related to schizophrenia. Methods We used functional magnetic resonance imaging (fMRI) to collect blood oxygenated level dependent (BOLD) response data in six POCs and eight unrelated healthy controls while performing under conditions of sustained, selective and divided attention. Results The POCs indicated alterations in a widely distributed network of regions involved in attention processes, such as the prefrontal and temporal (including the parahippocampal gyrus) cortices, in addition to the anterior cingulate gyrus. More specifically, a general reduction in BOLD response was found in these areas compared to the healthy participants during attention processes. Conclusion These preliminary findings of decreased activity in POCs indicate that this more homogeneous population of unaffected relatives share similar neural abnormalities with people with schizophrenia, suggesting that reduced BOLD activity in the attention network may be an intermediate marker for schizophrenia. PMID:18834530

  13. Functional Magnetic Resonance Imaging (fMRI) Neurofeedback: Implementations and Applications

    PubMed Central

    DEWIPUTRI, Wan Ilma; AUER, Tibor

    2013-01-01

    Neurofeedback (NFB) allows subjects to learn how to volitionally influence the neuronal activation in the brain by employing real-time neural activity as feedback. NFB has already been performed with electroencephalography (EEG) since the 1970s. Functional MRI (fMRI), offering a higher spatial resolution, has further increased the spatial specificity. In this paper, we briefly outline the general principles behind NFB, the implementation of fMRI-NFB studies, the feasibility of fMRI-NFB, and the application of NFB as a supplementary therapy tool. PMID:24643368

  14. Differences in span task performance recorded in a functional magnetic resonance imaging (fMRI) simulator compared to a standard laboratory condition 

    E-print Network

    Harcourt-Brown, Sally

    2006-01-01

    Forty-eight participants completed a working memory span task in a functional magnetic imaging (fMRI) simulator and laboratory. Differences in performance between the two conditions were investigated. The trends in the ...

  15. 1. INTRODUCTION Functional Magnetic Resonance Imaging (fMRI) is a rapidly developing tool that enables cognitive

    E-print Network

    Genovese, Christopher

    . Current methods for analyzing fMRI data attack what we call the localization problem: How can data from to exercise specific motor, sensory, or cognitive processes, and the measured MR signal contains information. Psychologists hope to use fMRI data to build and test theoretical models of human cognition, but to do this

  16. Network Modeling for Functional Magnetic Resonance Imaging (fMRI) Signals during Ultra-Fast Speech Comprehension in Late-Blind Listeners

    PubMed Central

    Dietrich, Susanne; Hertrich, Ingo; Ackermann, Hermann

    2015-01-01

    In many functional magnetic resonance imaging (fMRI) studies blind humans were found to show cross-modal reorganization engaging the visual system in non-visual tasks. For example, blind people can manage to understand (synthetic) spoken language at very high speaking rates up to ca. 20 syllables/s (syl/s). FMRI data showed that hemodynamic activation within right-hemispheric primary visual cortex (V1), bilateral pulvinar (Pv), and left-hemispheric supplementary motor area (pre-SMA) covaried with their capability of ultra-fast speech (16 syllables/s) comprehension. It has been suggested that right V1 plays an important role with respect to the perception of ultra-fast speech features, particularly the detection of syllable onsets. Furthermore, left pre-SMA seems to be an interface between these syllabic representations and the frontal speech processing and working memory network. So far, little is known about the networks linking V1 to Pv, auditory cortex (A1), and (mesio-) frontal areas. Dynamic causal modeling (DCM) was applied to investigate (i) the input structure from A1 and Pv toward right V1 and (ii) output from right V1 and A1 to left pre-SMA. As concerns the input Pv was significantly connected to V1, in addition to A1, in blind participants, but not in sighted controls. Regarding the output V1 was significantly connected to pre-SMA in blind individuals, and the strength of V1-SMA connectivity correlated with the performance of ultra-fast speech comprehension. By contrast, in sighted controls, not understanding ultra-fast speech, pre-SMA did neither receive input from A1 nor V1. Taken together, right V1 might facilitate the “parsing” of the ultra-fast speech stream in blind subjects by receiving subcortical auditory input via the Pv (= secondary visual pathway) and transmitting this information toward contralateral pre-SMA. PMID:26148062

  17. Network Modeling for Functional Magnetic Resonance Imaging (fMRI) Signals during Ultra-Fast Speech Comprehension in Late-Blind Listeners.

    PubMed

    Dietrich, Susanne; Hertrich, Ingo; Ackermann, Hermann

    2015-01-01

    In many functional magnetic resonance imaging (fMRI) studies blind humans were found to show cross-modal reorganization engaging the visual system in non-visual tasks. For example, blind people can manage to understand (synthetic) spoken language at very high speaking rates up to ca. 20 syllables/s (syl/s). FMRI data showed that hemodynamic activation within right-hemispheric primary visual cortex (V1), bilateral pulvinar (Pv), and left-hemispheric supplementary motor area (pre-SMA) covaried with their capability of ultra-fast speech (16 syllables/s) comprehension. It has been suggested that right V1 plays an important role with respect to the perception of ultra-fast speech features, particularly the detection of syllable onsets. Furthermore, left pre-SMA seems to be an interface between these syllabic representations and the frontal speech processing and working memory network. So far, little is known about the networks linking V1 to Pv, auditory cortex (A1), and (mesio-) frontal areas. Dynamic causal modeling (DCM) was applied to investigate (i) the input structure from A1 and Pv toward right V1 and (ii) output from right V1 and A1 to left pre-SMA. As concerns the input Pv was significantly connected to V1, in addition to A1, in blind participants, but not in sighted controls. Regarding the output V1 was significantly connected to pre-SMA in blind individuals, and the strength of V1-SMA connectivity correlated with the performance of ultra-fast speech comprehension. By contrast, in sighted controls, not understanding ultra-fast speech, pre-SMA did neither receive input from A1 nor V1. Taken together, right V1 might facilitate the "parsing" of the ultra-fast speech stream in blind subjects by receiving subcortical auditory input via the Pv (= secondary visual pathway) and transmitting this information toward contralateral pre-SMA. PMID:26148062

  18. Ultra-fast speech comprehension in blind subjects engages primary visual cortex, fusiform gyrus, and pulvinar – a functional magnetic resonance imaging (fMRI) study

    PubMed Central

    2013-01-01

    Background Individuals suffering from vision loss of a peripheral origin may learn to understand spoken language at a rate of up to about 22 syllables (syl) per second - exceeding by far the maximum performance level of normal-sighted listeners (ca. 8 syl/s). To further elucidate the brain mechanisms underlying this extraordinary skill, functional magnetic resonance imaging (fMRI) was performed in blind subjects of varying ultra-fast speech comprehension capabilities and sighted individuals while listening to sentence utterances of a moderately fast (8 syl/s) or ultra-fast (16 syl/s) syllabic rate. Results Besides left inferior frontal gyrus (IFG), bilateral posterior superior temporal sulcus (pSTS) and left supplementary motor area (SMA), blind people highly proficient in ultra-fast speech perception showed significant hemodynamic activation of right-hemispheric primary visual cortex (V1), contralateral fusiform gyrus (FG), and bilateral pulvinar (Pv). Conclusions Presumably, FG supports the left-hemispheric perisylvian “language network”, i.e., IFG and superior temporal lobe, during the (segmental) sequencing of verbal utterances whereas the collaboration of bilateral pulvinar, right auditory cortex, and ipsilateral V1 implements a signal-driven timing mechanism related to syllabic (suprasegmental) modulation of the speech signal. These data structures, conveyed via left SMA to the perisylvian “language zones”, might facilitate – under time-critical conditions – the consolidation of linguistic information at the level of verbal working memory. PMID:23879896

  19. Cerebral activation in abstinent ecstasy (MDMA) users during a working memory task: a functional magnetic resonance imaging (fMRI) study.

    PubMed

    Daumann, Jörg; Fimm, Bruno; Willmes, Klaus; Thron, Armin; Gouzoulis-Mayfrank, Euphrosyne

    2003-05-01

    The popular recreational drug ecstasy (3,4-methylenedioxymethamphetamine=MDMA and related congeners) is neurotoxic upon central serotonergic systems in animal studies. So far, the most convincing evidence for neurotoxicity-related functional deficits in humans derives from neurocognitive studies demonstrating dose-related long-term learning and memory problems in ecstasy users. In our study we used functional magnetic resonance imaging (fMRI) and a working memory task to investigate cerebral activation in eleven heavy, but currently abstinent MDMA users and two equally sized groups of moderate users and non-users. There were no significant group differences in working memory performance and no differences in cortical activation patterns for a conservative level of significance. However, for a more liberal statistical criterion, both user groups showed stronger activations than controls in right parietal cortex. Furthermore, heavy users had a weaker blood oxygenation level-dependent (BOLD) response than moderate users and controls in frontal and temporal areas. Our results may indicate subtle altered brain functioning associated with prior MDMA use, although alternative interpretations of these group differences must be considered. PMID:12706227

  20. Real-time functional magnetic resonance imaging: methods and applications

    Microsoft Academic Search

    Nikolaus Weiskopf; Ranganatha Sitaram; Oliver Josephs; Ralf Veit; Frank Scharnowski; Rainer Goebele; Niels Birbaumer; Ralf Deichmann; Klaus Mathiakf

    Functional magnetic resonance imaging (fMRI) has been limited by time-consuming data analysis and a low signal-to-noise ratio, impeding online analysis. Recent advances in acquisition techniques, computational power and algorithms increased the sensitivity and speed of fMRI significantly, making real-time analysis and display of fMRI data feasible. So far, most reports have focused on the technical aspects of real-time fMRI (rtfMRI).

  1. A Bayesian time course model for functional magnetic resonance imaging

    E-print Network

    Worsley, Keith

    to a small number of pre-selected isolated regions (`plots'), such as Broca's or Wernicke's areas Magnetic Resonance Imaging (fMRI), and brain mapping in general, presents statisticians with new challenges

  2. Decoding brain states using functional magnetic resonance imaging

    Microsoft Academic Search

    Dongha Lee; Changwon Jang; Hae-Jeong Park

    2011-01-01

    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.

  3. Functional magnetic resonance imaging of real and sham acupuncture

    Microsoft Academic Search

    TODD B. PARRISH; ALISSA SCHAEFFER; MADELYN CATANESE; MARY J. ROGEL

    2005-01-01

    Functional magnetic resonance imaging (fMRI) is an ideal method to noninvasively explore the whole brain for cortical activation related to acupuncture. The results from this study demonstrate that fMRI can identify specific cortical regions associated with acupuncture stimulation. The choice of acupuncture stimulation using visual or auditory points simplifies the interpretation of the results because the anatomic correlates are well

  4. Pitfalls in fMRI

    Microsoft Academic Search

    Sven Haller; Andreas J. Bartsch

    2009-01-01

    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

  5. Behavioral/Systems/Cognitive Functional Magnetic Resonance Imaging Reveals the

    E-print Network

    Murray, Scott

    magnetic resonance imaging (fMRI) has been extensively used to study the neural sub- strates of the handBehavioral/Systems/Cognitive Functional Magnetic Resonance Imaging Reveals the Neural Substrates the everyday act of reaching out to pick up a coffee cup seems like a single fluid action, arguably

  6. Understanding Understanding Source Code with Functional Magnetic Resonance Imaging

    E-print Network

    Kaestner, Christian

    Understanding Understanding Source Code with Functional Magnetic Resonance Imaging Janet Siegmund languages, tools, or coding conventions to support developers in their everyday work. In this paper, we explore whether functional magnetic resonance imaging (fMRI), which is well established in cognitive

  7. MRI (Magnetic Resonance Imaging)

    MedlinePLUS

    ... Criteria for Significant Risk Investigations of Magnetic Resonance Diagnostic Devices - Guidance for Industry and Food and Drug Administration ... the Submission Of Premarket Notifications for Magnetic Resonance Diagnostic Devices (Withdrawn) A Primer on Medical Device Interactions with ...

  8. Pediatric magnetic resonance imaging

    SciTech Connect

    Cohen, M.D.

    1986-01-01

    This book defines the current clinical potential of magnetic resonance imaging and focuses on direct clinical work with pediatric patients. A section dealing with the physics of magnetic resonance imaging provides an introduction to enable clinicians to utilize the machine and interpret the images. Magnetic resonance imaging is presented as an appropriate imaging modality for pediatric patients utilizing no radiation.

  9. Nuclear Magnetic Resonance

    NASA Astrophysics Data System (ADS)

    Andrew, E. R.

    2009-06-01

    Author's preface; 1. Introduction; 2. Basic theory; 3. Experimental methods; 4. Measurement of nuclear properties and general physical applications; 5. Nuclear magnetic resonance in liquids and gases; 6. Nuclear magnetic resonance in non-metallic solids; 7. Nuclear magnetic resonance in metals; 8. Quadrupole effects; Appendices 1-6; Glossary of symbols; Bibliography and author index; Subject index.

  10. How fMRI Can Inform Cognitive Theories

    E-print Network

    Kanwisher, Nancy

    How can functional magnetic resonance imaging (fMRI) advance cognitive theory? Some have argued that fMRI can do little beyond localizing brain regions that carry out certain cognitive functions (and may not even be able ...

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

    PubMed Central

    Burns, Gully A.P.C.; Turner, Jessica A.

    2015-01-01

    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

  12. Functional Magnetic Resonance Imaging and Radiosurgical Dose Planning

    Microsoft Academic Search

    Michael Schulder; Jose Vega; Venkat Narra; Alexander Jacobs; Andrew Kalnin; Gudrun Lange; Wen-Ching Liu

    1999-01-01

    Objective: To assess the effect of functional magnetic resonance imaging (fMRI) on stereotactic radiosurgical (SRS) dose planning. Methods: Patients included those undergoing SRS whose lesions were in or near areas that could be identified with fMRI. After processing, an fMR scan was registered to the anatomic scan, and this dataset was registered to a stereotactic CT scan. The imaged functional

  13. Investigation of BOLD fMRI Resonance Frequency Shifts and Quantitative Susceptibility Changes at 7 T

    PubMed Central

    Bianciardi, Marta; van Gelderen, Peter; Duyn, Jeff H.

    2013-01-01

    Although blood oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI) experiments of brain activity generally rely on the magnitude of the signal, they also provide frequency information that can be derived from the phase of the signal. However, because of confounding effects of instrumental and physiological origin, BOLD related frequency information is difficult to extract and therefore rarely used. Here, we explored the use of high field (7 T) and dedicated signal processing methods to extract frequency information and use it to quantify and interpret blood oxygenation and blood volume changes. We found that optimized preprocessing improves detection of task-evoked and spontaneous changes in phase signals and resonance frequency shifts over large areas of the cortex with sensitivity comparable to that of magnitude signals. Moreover, our results suggest the feasibility of mapping BOLD quantitative susceptibility changes in at least part of the activated area and its largest draining veins. Comparison with magnitude data suggests that the observed susceptibility changes originate from neuronal activity through induced blood volume and oxygenation changes in pial and intracortical veins. Further, from frequency shifts and susceptibility values, we estimated that, relative to baseline, the fractional oxygen saturation in large vessels increased by 0.02–0.05 during stimulation, which is consistent to previously published estimates. Together, these findings demonstrate that valuable information can be derived from fMRI imaging of BOLD frequency shifts and quantitative susceptibility changes. PMID:23897623

  14. Brain functional magnetic resonance imaging response to glucose and fructose infusions in humans

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Objective: In animals, intracerebroventricular glucose and fructose have opposing effects on appetite and weight regulation. In humans, functional brain magnetic resonance imaging (fMRI) studies during carbohydrate ingestion suggest that glucose may regulate HT signaling but are potentially confoun...

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

    E-print Network

    Texas at Austin, University of

    hemodynamic correlates using functional magnetic resonance imaging (fMRI) with blood oxygen-level dependent-surface algorithms to create a smooth sur- face representation at the gray-white interface and pial membrane

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

    Microsoft Academic Search

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

    2011-01-01

    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

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

    Microsoft Academic Search

    G. Ganis; J. P. Rosenfeld; J. Meixner; R. A. Kievit; H. Schendan

    2010-01-01

    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

  18. fMRI contrast at high and ultrahigh magnetic fields: Insight from complementary methods.

    PubMed

    Ciobanu, Luisa; Solomon, Eddy; Pyatigorskaya, Nadya; Roussel, Tangi; Le Bihan, Denis; Frydman, Lucio

    2015-06-01

    This manuscript examines the origins and nature of the function-derived activation detected by magnetic resonance imaging at ultrahigh fields using different encoding methods. A series of preclinical high field (7T) and ultra-high field (17.2T) fMRI experiments were performed using gradient echo EPI, spin echo EPI and spatio-temporally encoded (SPEN) strategies. The dependencies of the fMRI signal change on the strength of the magnetic field and on different acquisition and sequence parameters were investigated. Artifact-free rat brain images with good resolution in all areas, as well as significant localized activation maps upon forepaw stimulation, were obtained in a single scan using fully refocused SPEN sequences devoid of T2* effects. Our results showed that, besides the normal T2-weighted BOLD contribution that arises in spin-echo sequences, fMRI SPEN signals contain a strong component caused by apparent T1-related effects, demonstrating the potential of such technique for exploring functional activation in rodents and on humans at ultrahigh fields. PMID:25795340

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

    Microsoft Academic Search

    David A Williams; Richard H Gracely

    2006-01-01

    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

  20. Magnetic resonance imaging: prologue

    SciTech Connect

    Jacobson, H.G.

    1987-12-11

    Magnetic resonance imaging is becoming an increasingly important method of diagnostic imaging. This new method can compete with computed tomography for several applications, especially those involving the central nervous system. Magnetic resonance imaging is rapidly evolving, and several advances can be anticipated in the near future.

  1. Molecular magnetic resonance imaging

    PubMed Central

    Hengerer, A; Grimm, J

    2006-01-01

    Molecular MRI (mMRI) is a special implementation of Molecular Imaging for the non-invasive visualisation of biological processes at the cellular and molecular level. More specifically, mMRI comprises the contrast agent-mediated alteration of tissue relaxation times for the detection and localisation of molecular disease markers (such as cell surface receptors, enzymes or signaling molecules), cells (e.g. lymphocytes, stem cells) or therapeutic drugs (e.g. liposomes, viral particles). MRI yields topographical, anatomical maps; functional MRI (fMRI) provides rendering of physiologic functions and magnetic resonance spectroscopy (MRS) reveals the distribution patterns of some specific metabolites. mMRI provides an additional level of information at the molecular or cellular level, thus extending MRI further beyond the anatomical and physiological level. These advances brought by mMRI are mandatory for MRI to be competitive in the age of molecular medicine. mMRI is already today increasingly used for research purposes, e.g. to facilitate the examination of cell migration, angiogenesis, apoptosis or gene expression in living organisms. In medical diagnostics, mMRI will pave the way toward a significant improvement in early detection of disease, therapy planning or monitoring of outcome and will therefore bring significant improvement in the medical treatment for patients. In general, Molecular Imaging demands high sensitivity equipment, capable of quantitative measurements to detect probes that interact with targets at the pico- or nanomolar level. The challenge to detect such sparse targets can be exemplified with cell surface receptors, a common target for molecular imaging. At high expression levels (bigger than 106 per cell) the receptor concentration is approx. 1015 per ml, i.e. the concentration is in the micromole range. Many targets, however, are expressed in even considerably lower concentrations. Therefore the most sensitive modalities, namely nuclear imaging (PET and SPECT) have always been at the forefront of Molecular Imaging, and many nuclear probes in clinical use today are already designed to detect molecular mechanisms (such as FDG, detecting high glucose metabolism). In recent years however, Molecular Imaging has commanded attention from beyond the field of nuclear medicine. Further imaging modalities to be considered for molecular imaging primarily include optical imaging, MRI and ultrasound. PMID:21614236

  2. Applications of functional magnetic resonance imaging for market research

    Microsoft Academic Search

    Peter Kenning; Hilke Plassmann; Dieter Ahlert

    2007-01-01

    Purpose – The purpose of this paper is to provide a brief overview of the methodology of several brain imaging techniques and in particular, functional magnetic resonance imaging (fMRI) and its potential implications for market research. The aim is to enable the reader both to understand this emerging methodology and to conduct independent research in the area. Design\\/methodology\\/approach – A

  3. Large-Scale, High-Resolution Neurophysiological Maps Underlying fMRI of Macaque Temporal Lobe

    E-print Network

    Issa, Elias

    Maps obtained by functional magnetic resonance imaging (fMRI) are thought to reflect the underlying spatial layout of neural activity. However, previous studies have not been able to directly compare fMRI maps to high-resolution ...

  4. A client-server software application for statistical analysis of fMRI data

    E-print Network

    Choudhary, Vijay Singh, 1979-

    2004-01-01

    Statistical analysis methods used for interrogating functional magnetic resonance imaging (fMRI) data are complex and continually evolving. There exist a scarcity of educational material for fMRI. Thus, an instructional ...

  5. Nuclear magnetic resonance gyroscope

    SciTech Connect

    Grover, B.C.

    1984-02-07

    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.

  6. Magnetic Resonance Imaging of the Retina

    PubMed Central

    Duong, Timothy Q.; Muir, Eric R.

    2010-01-01

    This paper reviews recent developments in high-resolution magnetic resonance imaging (MRI) and its application to image anatomy, physiology, and function in the retina of animals. It describes technical issues and solutions in performing retinal MRI, anatomical MRI, blood oxygenation level-dependent functional MRI (fMRI), and blood-flow MRI both of normal retinas and of retinal degeneration. MRI offers unique advantages over existing retinal imaging techniques, including the ability to image multiple layers without depth limitation and to provide multiple clinically relevant data in a single setting. Retinal MRI has the potential to complement existing retinal imaging techniques. PMID:19763752

  7. Voxel magnetic field disturbance from remote vasculature in BOLD fMRI

    NASA Astrophysics Data System (ADS)

    Chen, Zikuan; Chen, Zeyuan; Calhoun, Vince

    2011-03-01

    The mechanism of blood oxygenation-level dependent (BOLD) functional magnetic resonance imaging (fMRI) lies in the detection of blood-induced magnetic field disturbance during brain activity. A magnetic dipole induces a magnetic field in 3D space, which is represented by a 3D kernel that shows orientation-dependent decay in space (with a radial distant decay factor of 1/r3), bipolar values, and revolution symmetry. By representing the intravascular blood space with a pack of magnetic dipoles, we can use the 3D kernel to calculate the BOLD fieldmap by a 3D convolution. In our implementation, a vasculature-laden voxel of interest (VOI) is represented by a matrix at a grid resolution(~1micron), and the intravascular space is filled with macroscopic blood magnetic dipoles (each is defined for a matrix element sitting in the blood space). Based on the magnetic dipole model of blood magnetization and the convolution algorithm, we calculate the effect of exterior vasculature (from nearest neighborhood as well as from farther or remote surrounding) on the BOLD fieldmap at the VOI. Our results show that only vessels at the VOI boundary region impose a noticeable influence, and this effect increases slightly with vessel size. The effect of remote vasculature (sitting in voxels outside the nearest neighborhood) is ignorable. We also discuss the case of asymmetrical surroundings.

  8. Magnetic Resonance Online Texts

    NSDL National Science Digital Library

    S�½kora, Stanislav

    This well-organized and very thorough website was developed by the physicist Stanislav Sykora with the aim of providing free online texts, theses, and course materials on the subjects of magnetic resonance (MR), magnetic resonance imaging (MRI), nuclear-magnetic resonance (NMR) and other related topics. The amount of material on the site is impressive. At the top of the page are links to an "MR Blog", as well as to "MR Links" and the "Site Plan & SEARCH". The NMR/MRI Extras section on the right side of the page is particularly useful for visitors interested in all things about MR. Its links to "Events" provides an up-to-date list of symposia, conferences, and meetings, along with links to the events' sites. The "Societies" link offers at least 50 groups about MR, some of which are country-based, and others that are region- or application-based.

  9. Functional Magnetic Resonance in the Evaluation of Oesophageal Motility Disorders

    PubMed Central

    Covotta, Francesco; Piretta, Luca; Badiali, Danilo; Laghi, Andrea; Biondi, Tommaso; Corazziari, Enrico S.; Panebianco, Valeria

    2011-01-01

    Functional magnetic resonance imaging (fMRI) has been recently proposed for the evaluation of the esophagus. Our aim is to assess the role of fMRI as a technique to assess morphological and functional parameters of the esophagus in patients with esophageal motor disorders and in healthy controls. Subsequently, we assessed the diagnostic efficiency of fMRI in comparison to videofluoroscopic and manometric findings in the investigation of patients with esophageal motor disorders. Considering that fMRI was shown to offer valuable information on bolus transit and on the caliber of the esophagus, variations of these two parameters in the different types of esophageal motor alterations have been assessed. fMRI, compared to manometry and videofluoroscopy, showed that a deranged or absent peristalsis is significantly associated with slower transit time and with increased esophageal diameter. Although further studies are needed, fMRI represents a promising noninvasive technique for the integrated functional and morphological evaluation of esophageal motility disorders. PMID:21904543

  10. Combined fMRI and electrical microstimulation to determine functional connections in visual areas of the primate brain

    E-print Network

    Ekstrom, Leeland Bruce

    2009-01-01

    The use of functional magnetic resonance imaging (fMRI) to study the non-human primate brain has been developed over the past decade. Primate fMRI has many attractive features: it allows validation of previous homology ...

  11. fMRI detection with spatial regularization

    E-print Network

    Ou, Wanmei

    2005-01-01

    Functional Magnetic Resonant Imaging (fMRI) is a non-invasive imaging technique used to study the brain. Neuroscientists have developed various algorithms to determine which voxels of the images are active. Most of these ...

  12. Magnetic Resonance Imaging and Magnetic Resonance Spectroscopy in Dementias

    PubMed Central

    Hsu, Yuan-Yu; Du, An-Tao; Schuff, Norbert; Weiner, Michael W.

    2007-01-01

    This article reviews recent studies of magnetic resonance imaging and magnetic resonance spectroscopy in dementia, including Alzheimer's disease, frontotemporal dementia, dementia with Lewy bodies, idiopathic Parkinson's disease, Huntington's disease, and vascular dementia. Magnetic resonance imaging and magnetic resonance spectroscopy can detect structural alteration and biochemical abnormalities in the brain of demented subjects and may help in the differential diagnosis and early detection of affected individuals, monitoring disease progression, and evaluation of therapeutic effect. PMID:11563438

  13. Coronary magnetic resonance angiography

    Microsoft Academic Search

    Matthias Stuber; Robert G. Weiss

    2007-01-01

    Coronary magnetic resonance angiography (MRA) is a pow- erful noninvasive technique with high soft-tissue contrast for the visualization of the coronary anatomy without X-ray exposure. Due to the small dimensions and tortuous na- ture of the coronary arteries, a high spatial resolution and sufficient volumetric coverage have to be obtained. How- ever, this necessitates scanning times that are typically much

  14. Magnetic resonance imaging

    SciTech Connect

    Stark, D.D.; Bradley, W.G. Jr.

    1988-01-01

    The authors present a review of magnetic resonance imaging. Many topics are explored from instrumentation, spectroscopy, blood flow and sodium imaging to detailed clinical applications such as the differential diagnosis of multiple sclerosis or adrenal adenoma. The emphasis throughout is on descriptions of normal multiplanar anatomy and pathology as displayed by MRI.

  15. Stepping stone sampling for retrieving artifact-free electroencephalogram during functional magnetic resonance imaging

    Microsoft Academic Search

    Kimitaka Anami; Takeyuki Mori; Fumiko Tanaka; Yusuke Kawagoe; Jun Okamoto; Masaru Yarita; Takashi Ohnishi; Masato Yumoto; Hiroshi Matsuda; Osamu Saitoh

    2003-01-01

    Ballistocardiogram and imaging artifacts cause major interference with simultaneous electroencephalogram (EEG) and functional magnetic resonance imaging (fMRI) recording. In particular, the large amplitude of the imaging artifact precludes easy retrieval of EEG signals during fMRI scanning. Recording with 20,000-Hz digitization rate combined with 3000-Hz low-pass filter revealed the real waveform of the imaging artifact, in which it was elucidated that

  16. Multifractal analysis of Arterial Spin Labeling functional Magnetic Resonance Imaging of the brain

    Microsoft Academic Search

    Filipe Soares; Inês Sousa; Filipe Janela; João Seabra; Manuela Pereira; Mário M. Freire

    2010-01-01

    This work proposes a multifractal analysis of the time series derived from ASL fMRI (Arterial Spin Labeling functional Magnetic Resonance Imaging) to detect brain activated regions in response to an unknown stimulus. In contrast to standard model-based activation analysis, no prior knowledge of the expected haemodynamic response has to be assumed for extracting activation patterns from fMRI. The ASL time

  17. Organization of language networks in children: Functional magnetic resonance imaging studies

    Microsoft Academic Search

    Bonnie C. Sachs; William D. Gaillard

    2003-01-01

    Functional magnetic resonance imaging (fMRI) is a relatively new neuroimaging procedure that has been used to study a wide\\u000a variety of cognitive phenomena in adults, including attention, language, and memory. More recently, this technique has been\\u000a successfully applied to pediatric populations as well. In particular, many investigators have employed fMRI as a tool to study\\u000a language development in normal children.

  18. Hemodynamic Assessment of Carotid Stenosis by Functional Magnetic Resonance Imaging

    Microsoft Academic Search

    Ulf Jensen; Kathrin Börsch; Robert Stingele; Olav Jansen; Karsten Alfke

    2008-01-01

    Background: Functional magnetic resonance imaging (fMRI) is a method usually used to identify cortical representations of cerebral functions. Some studies and case reports suggest that stenoses of the brain-supplying arteries influence the BOLD (blood-oxygenation-level-dependent) signal. The objective of this study was to find out whether the BOLD signal differs in the ipsilateral hemisphere of patients with hemodynamically relevant and those

  19. Experiences with functional magnetic resonance imaging at 1 tesla

    Microsoft Academic Search

    A P JONES; D G HUGHES; D S BRETTLE; L ROBINSON; J R SYKES; Q AZIZ; S HAMDY; D G THOMPSON; S W G DERBYSHIRE; A C N CHEN

    1998-01-01

    Functional magnetic resonance imaging (fMRI) has been performed on a standard 1 T system using a pulse sequence developed to utilize blood oxygen level dependent (BOLD) contrast and an oV-line analysis routine using correlation techniques. The sequence and the data analysis routine have been validated by reproducing the conventional hand movement paradigm studies reported by numerous other workers. Our work

  20. Magnetic resonance imaging methodology

    Microsoft Academic Search

    Ewald Moser; Andreas Stadlbauer; Christian Windischberger; Harald H. Quick; Mark E. Ladd

    2009-01-01

    Introduction  Magnetic resonance (MR) methods are non-invasive techniques to provide detailed, multi-parametric information on human anatomy,\\u000a function and metabolism. Sensitivity, specificity, spatial and temporal resolution may, however, vary depending on hardware\\u000a (e.g., field strength, gradient strength and speed) and software (optimised measurement protocols and parameters for the various\\u000a techniques). Furthermore, multi-modality imaging may enhance specificity to better characterise complex disease patterns.

  1. Magnetic resonance urography

    Microsoft Academic Search

    John R. Leyendecker; John W. Gianini

    2009-01-01

    Excellent contrast resolution and lack of ionizing radiation make magnetic resonance urography (MRU) a promising technique\\u000a for noninvasively evaluating the entire urinary tract. While MRU currently lags behind CT urography (CTU) in spatial resolution\\u000a and efficiency, new hardware and sequence developments have contributed to a resurgence of interest in MRU techniques. By\\u000a combining unenhanced sequences with multiphase contrast-enhanced and excretory

  2. Nuclear Magnetic Resonance Gyroscope

    NASA Astrophysics Data System (ADS)

    Larsen, Michael; Griffith, Robert; Bulatowicz, Michael

    2014-03-01

    The navigation grade micro Nuclear Magnetic Resonance Gyroscope (micro-NMRG) being developed by the Northrop Grumman Corporation (NGC) has concluded the fourth and final phase of the DARPA Navigation Grade Integrated Micro Gyro (NGIMG) program. Traditional MEMS gyros utilize springs as an inherent part of the sensing mechanism, leading to bias and scale factor sensitivity to acceleration and vibration. As a result, they have not met performance expectations in real world environments and to date have been limited to tactical grade applications. The Nuclear Magnetic Resonance Gyroscope (NMRG) utilizes the fixed precession rate of a nuclear spin in a constant magnetic field as an inertial reference for determining rotation. The nuclear spin precession rate sensitivity to acceleration and vibration is negligible for most applications. Therefore, the application of new micro and batch fabrication methods to NMRG technology holds great promise for navigation grade performance in a low cost and compact gyro. This presentation will describe the operational principles, design basics, and demonstrated performance of the NMRG including an overview of the NGC designs developed and demonstrated in the DARPA gyro development program.

  3. Breast magnetic resonance imaging.

    PubMed

    Johnson, Marlene M

    2012-01-01

    Mammography has long been considered the gold standard for screening breast cancer. Although it reduces the risk of breast cancer mortality by enabling early diagnosis, it does not detect all breast cancers. Numerous breast imaging technologies are emerging as effective adjunctive diagnostic tools when mammography results are negative or inconclusive. Contrast-enhanced magnetic resonance (CE-MR) imaging, in particular, has demonstrated a high sensitivity and has proven to be most effective, especially with patients at high risk for developing breast cancer. This article discusses the clinical applications for breast MR imaging, use of CE-MR for breast cancer detection, and other emerging breast imaging technologies. PMID:22267704

  4. Nuclear Magnetic Resonance Gyroscope

    NASA Astrophysics Data System (ADS)

    Larsen, Michael

    2011-05-01

    The navigation grade micro Nuclear Magnetic Resonance Gyroscope (micro-NMRG) being developed by the Northrop Grumman Corporation is currently in phase 4 of the DARPA Navigation Grade Integrated Micro Gyro (NGIMG) program. The micro-NMRG technology is pushing the boundaries of size, weight, power, and performance allowing new small platform applications of navigation grade Inertial Navigation System (INS) technology. Information on the historical development of the technology, basics of operation, task performance goals, application opportunities, and a phase 2 sample of earth rate measurement data will be presented. Funding Provided by the Defense Advanced Research Projects Agency (DARPA)

  5. nuclear magnetic resonance gyroscope

    SciTech Connect

    Karwacki, F. A.; Griffin, J.

    1985-04-02

    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.

  6. Magnetic resonance cell

    SciTech Connect

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

    1984-05-01

    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.

  7. Classification of whole brain fMRI activation patterns

    E-print Network

    Balc?, Serdar Kemal

    2008-01-01

    Functional magnetic resonance imaging (fMRI) is an imaging technology which is primarily used to perform brain activation studies by measuring neural activity in the brain. It is an interesting question whether patterns ...

  8. Lying about facial recognition: An fMRI study

    Microsoft Academic Search

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

    2009-01-01

    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)

  9. Study Design in fMRI: Basic Principles

    ERIC Educational Resources Information Center

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

    2006-01-01

    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,…

  10. Lying about Facial Recognition: An fMRI Study

    ERIC Educational Resources Information Center

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

    2009-01-01

    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,…

  11. High-resolution functional magnetic resonance imaging of the animal brain

    Microsoft Academic Search

    Seong-Gi Kim; Kamil Ugurbil

    2003-01-01

    To fully understand brain function, one must look beyond the level of a single neuron. By elucidating the spatial properties of the columnar and laminar functional architectures, information regarding the neural processing in the brain can be gained. To map these fine functional structures noninvasively and repeatedly, functional magnetic resonance imaging (fMRI) can be employed. In this article the basic

  12. Functional Magnetic Resonance Imaging of Cognitive Processing in Young Adults with Down Syndrome

    ERIC Educational Resources Information Center

    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.

    2011-01-01

    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…

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

    Microsoft Academic Search

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

    2004-01-01

    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

  14. Low field magnetic resonance imaging

    DOEpatents

    Pines, Alexander (Berkeley, CA); Sakellariou, Dimitrios (Billancourt, FR); Meriles, Carlos A. (Fort Lee, NJ); Trabesinger, Andreas H. (London, GB)

    2010-07-13

    A method and system of magnetic resonance imaging does not need a large homogenous field to truncate a gradient field. Spatial information is encoded into the spin magnetization by allowing the magnetization to evolve in a non-truncated gradient field and inducing a set of 180 degree rotations prior to signal acquisition.

  15. Stray Field Magnetic Resonance Imaging

    Microsoft Academic Search

    K. Zick

    1994-01-01

    In many applications of magnetic resonance imaging large linewidths means that to achieve useful resolution in the image large magnetic field gradients should be employed. This paper outlines the principles of stray field imaging that utilises the large gradients intrinsic to the fringe field of superconducting solenoidal magnets. Examples of images from strongly broadened everyday objects are given.

  16. Nuclear magnetic resonance contrast agents

    DOEpatents

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

    1997-12-30

    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.

  17. Recent developments in optimal experimental designs for functional magnetic resonance imaging

    PubMed Central

    Kao, Ming-Hung; Temkit, M'hamed; Wong, Weng Kee

    2014-01-01

    Functional magnetic resonance imaging (fMRI) is one of the leading brain mapping technologies for studying brain activity in response to mental stimuli. For neuroimaging studies utilizing this pioneering technology, there is a great demand of high-quality experimental designs that help to collect informative data to make precise and valid inference about brain functions. This paper provides a survey on recent developments in experimental designs for fMRI studies. We briefly introduce some analytical and computational tools for obtaining good designs based on a specified design selection criterion. Research results about some commonly considered designs such as blocked designs, and m-sequences are also discussed. Moreover, we present a recently proposed new type of fMRI designs that can be constructed using a certain type of Hadamard matrices. Under certain assumptions, these designs can be shown to be statistically optimal. Some future research directions in design of fMRI experiments are also discussed. PMID:25071884

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

    PubMed

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

    2011-03-01

    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

  19. HIV and Aging Independently Affect Brain Function as Measured by Functional Magnetic Resonance Imaging

    PubMed Central

    Ances, Beau M.; Vaida, Florin; Yeh, Melinda J.; Liang, Christine L.; Buxton, Richard B.; Letendre, Scott; McCutchan, J. Allen; Ellis, Ronald J.

    2009-01-01

    We investigated interactions between HIV and aging on brain function demands using functional magnetic resonance imaging (fMRI). A multiple regression model studied the association and interaction between fMRI measures, HIV serostatus, and age for 26 HIV infected (HIV+) and 25 seronegative (HIV?) subjects. While HIV serostatus and age independently affected fMRI measures, no interaction occurred. Functional brain demands in HIV+ subjects were equivalent to ~15–20 year older HIV? subjects. Frailty parallels between HIV and aging could result from continued immunological challenges depleting resources and triggering increased metabolic demands. fMRI could be a non-invasive biomarker to assess HIV in the brain. PMID:20047503

  20. Functional Magnetic Resonance Imaging Brain Mapping in Psychiatry: Methodological Issues Illustrated in a Study of Working Memory in Schizophrenia

    Microsoft Academic Search

    Joseph H Callicott; Nicolas F Ramsey; Kathleen Tallent; Alessandro Bertolino; Michael B Knable; Richard Coppola; Terry Goldberg; Peter van Gelderen; Venkata S Mattay; Joseph A Frank; Chrit TW Moonen; Daniel R Weinberger

    1998-01-01

    Functional magnetic resonance imaging (fMRI) is a potential paradigm shift in psychiatric neuroimaging. The technique provides individual, rather than group-averaged, functional neuroimaging data, but subtle methodological confounds represent unique challenges for psychiatric research. As an exemplar of the unique potential and problems of fMRI, we present a study of 10 inpatients with schizophrenia and 10 controls performing a novel “n

  1. Nuclear Magnetic Resonance

    NASA Astrophysics Data System (ADS)

    Reuhs, Bradley L.; Simsek, Senay

    Nuclear magnetic resonance (NMR) spectroscopy is a powerful analytical technique with a wide variety of applications. It may be used for complex structural studies, for protocol or process development, or as a simple quality assay for which structural information is important. It is nondestructive, and high-quality data may be obtained from milligram, even microgram, quantities of sample. Whereas other spectroscopy techniques may be used to determine the nature of the functional groups present in a sample, only NMR spectroscopy can provide the data necessary to determine the complete structure of a molecule. The applicability of NMR to food analysis has increased over the last three decades. In addition to improved instrumentation and much lower costs, very complex and specialized NMR techniques can now be routinely performed by a student or technician. These experiments can be set up with the click of a button/icon, as all the basic parameters are embedded into default experiment files listed in the data/work station software, and the results are obtained in a short time.

  2. Ethics in fMRI Studies

    Microsoft Academic Search

    Daniela Seixas; Margarida Ayres Basto

    2008-01-01

    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.

  3. Overview of fMRI analysis

    Microsoft Academic Search

    S M Smith

    2004-01-01

    fMRI (functional magnetic resonance imaging) is a powerful non-invasive tool in the study of the function of the brain, used, for example, by psychologists, psychia- trists and neurologists. fMRI can give high quality visualization of the location of activity in the brain resulting from sensory stimulation or cognitive function. It therefore allows the study of how the healthy brain functions,

  4. The fMRI Data Center

    NSDL National Science Digital Library

    Maintained by Dartmouth College, the fMRI Data Center serves as a repository for the functional magnetic resonance imaging data for peer-reviewed, published studies. Intended to help the fMRI research community "speed the progress and the understanding of cognitive processes and the neural substrates that underlie them," the fMRI Data Center is in the process of making all datasets and associated material completely Web-accessible. Currently, the datasets (36 total, with more added every year) are available as free CDs, which the fMRI Data Center will ship directly to interested users. The fMRI Data Center enthusiastically urges researchers to submit peer-reviewed articles and underlying datasets, and may eventually accept any pertinent data.

  5. Basics of magnetic resonance imaging

    SciTech Connect

    Oldendorf, W.; Oldendorf, W. Jr.

    1988-01-01

    Beginning with the behavior of a compass needle in a magnetic field, this text uses analogies from everyday experience to explain the phenomenon of nuclear magnetic resonance and how it is used for imaging. Using a minimum of scientific abbreviations and symbols, the basics of tissue visualization and characterization are presented. A description of the various types of magnets and scanners is followed by the practical advantages and limitations of MRI relative to x-ray CT scanning.

  6. Noble gas magnetic resonator

    DOEpatents

    Walker, Thad Gilbert; Lancor, Brian Robert; Wyllie, Robert

    2014-04-15

    Precise measurements of a precessional rate of noble gas in a magnetic field is obtained by constraining the time averaged direction of the spins of a stimulating alkali gas to lie in a plane transverse to the magnetic field. In this way, the magnetic field of the alkali gas does not provide a net contribution to the precessional rate of the noble gas.

  7. Methodological challenges and solutions in auditory functional magnetic resonance imaging

    PubMed Central

    Peelle, Jonathan E.

    2014-01-01

    Functional magnetic resonance imaging (fMRI) studies involve substantial acoustic noise. This review covers the difficulties posed by such noise for auditory neuroscience, as well as a number of possible solutions that have emerged. Acoustic noise can affect the processing of auditory stimuli by making them inaudible or unintelligible, and can result in reduced sensitivity to auditory activation in auditory cortex. Equally importantly, acoustic noise may also lead to increased listening effort, meaning that even when auditory stimuli are perceived, neural processing may differ from when the same stimuli are presented in quiet. These and other challenges have motivated a number of approaches for collecting auditory fMRI data. Although using a continuous echoplanar imaging (EPI) sequence provides high quality imaging data, these data may also be contaminated by background acoustic noise. Traditional sparse imaging has the advantage of avoiding acoustic noise during stimulus presentation, but at a cost of reduced temporal resolution. Recently, three classes of techniques have been developed to circumvent these limitations. The first is Interleaved Silent Steady State (ISSS) imaging, a variation of sparse imaging that involves collecting multiple volumes following a silent period while maintaining steady-state longitudinal magnetization. The second involves active noise control to limit the impact of acoustic scanner noise. Finally, novel MRI sequences that reduce the amount of acoustic noise produced during fMRI make the use of continuous scanning a more practical option. Together these advances provide unprecedented opportunities for researchers to collect high-quality data of hemodynamic responses to auditory stimuli using fMRI. PMID:25191218

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

    PubMed Central

    Logothetis, Nikos K

    2002-01-01

    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. PMID:12217171

  9. Interventional Cardiovascular Magnetic Resonance Imaging

    PubMed Central

    Saikus, Christina E.; Lederman, Robert J.

    2010-01-01

    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. PMID:19909937

  10. Functional Magnetic Resonance Imaging in Narcolepsy and the Kleine–Levin Syndrome

    PubMed Central

    Engström, Maria; Hallböök, Tove; Szakacs, Attila; Karlsson, Thomas; Landtblom, Anne-Marie

    2014-01-01

    This work aims at reviewing the present state of the art when it comes to understanding the pathophysiology of narcolepsy and the Kleine–Levin syndrome (KLS) from a neuroimaging point of view. This work also aims at discussing future perspectives of functional neuroimaging in these sleep disorders. We focus on functional magnetic resonance imaging (fMRI), which is a technique for in vivo measurements of brain activation in neuronal circuitries under healthy and pathological conditions. fMRI has significantly increased the knowledge on the affected neuronal circuitries in narcolepsy and the Kleine–Levin syndrome. It has been shown that narcolepsy is accompanied with disturbances of the emotional and the closely related reward systems. In the Kleine Levin syndrome, fMRI has identified hyperactivation of the thalamus as a potential biomarker that could be used in the diagnostic procedure. The fMRI findings in both narcolepsy and the Kleine–Levin syndrome are in line with previous structural and functional imaging studies. We conclude that fMRI in combination with multi-modal imaging can reveal important details about the pathophysiology in narcolepsy and the Kleine–Levin syndrome. In the future, fMRI possibly gives opportunities for diagnostic support and prediction of treatment response in individual patients. PMID:25009530

  11. A computerized tablet with visual feedback of hand position for functional magnetic resonance imaging

    PubMed Central

    Karimpoor, Mahta; Tam, Fred; Strother, Stephen C.; Fischer, Corinne E.; Schweizer, Tom A.; Graham, Simon J.

    2015-01-01

    Neuropsychological tests behavioral tasks that very commonly involve handwriting and drawing are widely used in the clinic to detect abnormal brain function. Functional magnetic resonance imaging (fMRI) may be useful in increasing the specificity of such tests. However, performing complex pen-and-paper tests during fMRI involves engineering challenges. Previously, we developed an fMRI-compatible, computerized tablet system to address this issue. However, the tablet did not include visual feedback of hand position (VFHP), a human factors component that may be important for fMRI of certain patient populations. A real-time system was thus developed to provide VFHP and integrated with the tablet in an augmented reality display. The effectiveness of the system was initially tested in young healthy adults who performed various handwriting tasks in front of a computer display with and without VFHP. Pilot fMRI of writing tasks were performed by two representative individuals with and without VFHP. Quantitative analysis of the behavioral results indicated improved writing performance with VFHP. The pilot fMRI results suggest that writing with VFHP requires less neural resources compared to the without VFHP condition, to maintain similar behavior. Thus, the tablet system with VFHP is recommended for future fMRI studies involving patients with impaired brain function and where ecologically valid behavior is important. PMID:25859201

  12. Optically induced parametric magnetic resonances

    NASA Astrophysics Data System (ADS)

    Jimenez, Ricardo; Knappe, Svenja; Kitching, John

    2011-05-01

    Optically pumped vector magnetometers based on zero-field resonances have reached very high sensitivities by operating at high atomic densities where dephasing due to spin-exchange collisions can be suppressed. Simplified setups, with just one laser beam have measured magnetic fields from the human brain and heart. A key feature in these magnetometers is the introduction of an rf magnetic field along the measurement axis to generate a parametric resonance. Lock-in detection of the transmitted light, at an odd harmonic of the modulation frequency, allows the reduction of the low frequency noise and generates a resonance with dispersive shape. Here we study a zero-field vector magnetometer where the parametric resonances are induced by the vector AC stark-shift of light. This approach does not produce any external magnetic field that could disturb the reading of other magnetometers in the vicinity and could provide an alternative in applications where an applied AC-field cannot be used. We have characterized the vector AC stark-shift effect of light on Rb atoms contained in a micromachined vapor cell with buffer gas. We have obtained parametric resonances induced by modulation of the light-shift. We also analyze the detunings and intensities of the light-shift beam that maintain the magnetometer within the spin-exchange relaxation-free regime.

  13. Breast Magnetic Resonance Imaging Techniques

    Microsoft Academic Search

    Nola M. Hylton

    Magnetic resonance imaging (MRI) of the breast is finding wider clinical application as an adjunct diagnostic procedure to mammography and ultrasound. Because of its high sensitivity and effectiveness in dense breast tissue, MRI can be a valuable addition to the diagnostic work up of a patient with a breast abnormality or biopsy-proven cancer. The major limitation of breast MRI is

  14. Magnetic resonance imaging of atherosclerosis

    Microsoft Academic Search

    T. Leiner; S. Gerretsen; R. Botnar; E. Lutgens; V. Cappendijk; E. Kooi; J. van Engelshoven

    2005-01-01

    Abundant data now link composition of the vascular wall, rather than the degree of luminal narrowing, with the risk for acute ischemic syndromes in the coronary, central nervous system, and peripheral arterial beds. Over the past few years, magnetic resonance angiography has evolved as a well-established method to determine the location and severity of advanced, lumen-encroaching atherosclerotic lesions. In addition,

  15. Nuclear magnetic resonance spectroscopy

    SciTech Connect

    Harris, R.K.

    1986-01-01

    NMR is remarkable in the number of innovations that have appeared and become established within the past five years. This thoroughly up-to-date account of the field explains fundamentals and applications of the NMR phenomenon from the viewpoint of a physical chemist. Beginning with descriptions of basic concepts involved in continuous wave operation, the book goes on to cover spectral analysis, relaxation phenomena, the effects of pulses, the Fourier transform model, double resonance and the effects of chemical exchange and quadrupolar interactions. The book also includes the new techniques for work on solids and for complicated pulse sequences, plus abundant figures and illustrative spectra.

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

    Microsoft Academic Search

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

    2008-01-01

    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-

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

    Microsoft Academic Search

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

    2010-01-01

    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

  18. Functional Magnetic Resonance Imaging of Story Listening in Adolescents and Young Adults with Down Syndrome: Evidence for Atypical Neurodevelopment

    ERIC Educational Resources Information Center

    Jacola, L. M.; Byars, A. W.; Hickey, F.; Vannest, J.; Holland, S. K.; Schapiro, M. B.

    2014-01-01

    Background: Previous studies have documented differences in neural activation during language processing in individuals with Down syndrome (DS) in comparison with typically developing individuals matched for chronological age. This study used functional magnetic resonance imaging (fMRI) to compare activation during language processing in young…

  19. Magnetic resonance imaging of oscillating electrical currents.

    PubMed

    Halpern-Manners, Nicholas W; Bajaj, Vikram S; Teisseyre, Thomas Z; Pines, Alexander

    2010-05-11

    Functional MRI has become an important tool of researchers and clinicians who seek to understand patterns of neuronal activation that accompany sensory and cognitive processes. However, the interpretation of fMRI images rests on assumptions about the relationship between neuronal firing and hemodynamic response that are not firmly grounded in rigorous theory or experimental evidence. Further, the blood-oxygen-level-dependent effect, which correlates an MRI observable to neuronal firing, evolves over a period that is 2 orders of magnitude longer than the underlying processes that are thought to cause it. Here, we instead demonstrate experiments to directly image oscillating currents by MRI. The approach rests on a resonant interaction between an applied rf field and an oscillating magnetic field in the sample and, as such, permits quantitative, frequency-selective measurements of current density without spatial or temporal cancellation. We apply this method in a current loop phantom, mapping its magnetic field and achieving a detection sensitivity near the threshold required for the detection of neuronal currents. Because the contrast mechanism is under spectroscopic control, we are able to demonstrate how ramped and phase-modulated spin-lock radiation can enhance the sensitivity and robustness of the experiment. We further demonstrate the combination of these methods with remote detection, a technique in which the encoding and detection of an MRI experiment are separated by sample flow or translation. We illustrate that remotely detected MRI permits the measurement of currents in small volumes of flowing water with high sensitivity and spatial resolution. PMID:20421504

  20. Optimized Design and Analysis of Sparse-Sampling fMRI Experiments

    E-print Network

    Perrachione, Tyler Kent

    Sparse-sampling is an important methodological advance in functional magnetic resonance imaging (fMRI), in which silent delays are introduced between MR volume acquisitions, allowing for the presentation of auditory stimuli ...

  1. Solutions to various problems in reversible cooling fMRI studies

    E-print Network

    Khachaturian, Mark Haig, 1979-

    2003-01-01

    Functional magnetic resonance imaging (fMRI) has been very useful in helping neuroscientists map the brain. One tool to investigate the interactions between brain regions is to disable a small region in the brain, and look ...

  2. Increasing the effect size in event-related fMRI studies

    Microsoft Academic Search

    MARTIN J. MCKEOWN; Z. JANE WANG; RAFEEF ABUGHARBIEH; TODD C. HANDY

    2006-01-01

    Independent component analysis (ICA) has proved to be a powerful method for exploratory analysis of functional magnetic resonance imaging (fMRI) data. It has been used to uncover unexpected activations in fMRI data derived from brain activation. ICA has been used to characterize other sources of variability in the fMRI signal besides task-related activity, as well as challenging some of the

  3. Magnetic resonance in solids

    SciTech Connect

    O'Connell, A.J.

    1992-01-01

    In this thesis electron paramagnetic resonance (EPR) and electro-nuclear double resonance (ENDOR) experiments are reported on paramagnetic defects in two host materials: (a) Cr[sup 3+] in the ferroelectric lecontite and (b) color centres and the Fe[sup 3+] centre in lithium oxide. A. Lecontite. Lecontite, NaNH[sub 4]SO[sub 4][center dot]2H[sub 2]O, undergoes a phase transition to a ferroelectric phase below [Tc] = 101 K. Reported here are EPR measurements on doped Cr[sup 3+] ions at two distinct sites, made at a variety of temperatures in an attempt to ascertain the details of the structural changes occurring at [Tc]. The room temperature data are compared to various models for the two defects using the Newman superposition model. The results show that the Cr[sup 3+] ions are at Na[sup +] sites, highly distorted due to charge compensation of the trivalent dopant and therefore that the EPR of these defects is not representative of the bulk material. B. Lithium oxide. Investigations of three defect in lithium oxide, Li[sub 2]O are reported here. (i) The electronic F[sup +] -centre has been investigated using EPR and [sup 7]Li ENDOR to determine the transferred hyperfine structure (THFS) due to hyperfine interactions of the defect wavefunction with the ligand nuclei. Comparison with F-centres in other simple ionic hosts shows that the centre is highly localized and this observation is explained by the charge states of the ligands and the defect site. (ii) EPR and [sup 7]Li ENDOR of the interstitial neutral hydrogen centre H[sup 0] show a novel tunnelling effect. At low temperatures the defect has tetragonal symmetry but at higher temperatures there is evidence of tunnelling between six equivalent sites, leading to effective cubic symmetry. (iii) THFS of Fe[sup 3+] centres, measured using [sup 7]Li ENDOR, interpreted using the Newman superposition model, are used to determine the distortions of the neighboring ligands.

  4. Wavelet-based multifractal analysis of fMRI time series

    Microsoft Academic Search

    Yu Shimizu; Markus Barth; Christian Windischberger; Ewald Moser; Stefan Thurner

    2004-01-01

    Functional magnetic resonance imaging (fMRI) time series are investigated with a multifractal method based on the Wavelet Modulus Maxima (WTMM) method to extract local singularity (“fractal”) exponents. The spectrum of singularity exponents of each fMRI time series is quantified by spectral characteristics including its maximum and the corresponding dimension. We found that the range of Hölder exponents in voxels with

  5. Medial temporal lobe activations in fMRI and PET studies of episodic encoding and retrieval

    Microsoft Academic Search

    Daniel L. Schacter; Anthony D. Wagner

    1999-01-01

    Early neuroimaging studies often failed to obtain evidence of medial temporal lobe (MTL) activation during episodic encoding or retrieval, but a growing number of studies using functional magnetic resonance imaging (fMRI) and positron emission tomography (PET) have provided such evidence. We review data from fMRI studies that converge on the conclusion that posterior MTL is associated with episodic encoding; too

  6. Magnetic Resonance Connectome Automated Pipeline

    E-print Network

    Gray, William R; Vogelstein, Joshua T; Landman, Bennett A; Prince, Jerry L; Vogelstein, R Jacob

    2011-01-01

    This manuscript presents a novel, tightly integrated pipeline for estimating a connectome, which is a comprehensive description of the neural circuits in the brain. The pipeline utilizes magnetic resonance imaging (MRI) data to produce a high-level estimate of the structural connectivity in the human brain. The Magnetic Resonance Connectome Automated Pipeline (MRCAP) is efficient and its modular construction allows researchers to modify algorithms to meet their specific requirements. The pipeline has been validated and over 200 connectomes have been processed and analyzed to date. This tool enables the prediction and assessment of various cognitive covariates, and this research is applicable to a variety of domains and applications. MRCAP will enable MR connectomes to be rapidly generated to ultimately help spur discoveries about the structure and function of the human brain.

  7. A Case Study of Magnetic Resonance Imaging of Cerebrovascular Reactivity: A Powerful Imaging Marker for Mild Traumatic Brain Injury

    PubMed Central

    Chan, Suk-tak; Evans, Karleyton C.; Rosen, Bruce R.; Song, Tian-yue; Kwong, Kenneth K.

    2015-01-01

    Primary objective To use breath-hold functional magnetic resonance imaging (fMRI) to localize the brain regions with impaired cerebrovascular reactivity (CVR) in a female patient diagnosed with mild traumatic brain injury (mTBI). The extent of impaired CVR was evaluated two months after concussion. Follow-up scan was performed one year post mTBI using the same breath-hold fMRI technique. Research design Case report. Methods and procedures fMRI blood oxygenation dependent level (BOLD) signals were measured under breath-hold challenge in a female mTBI patient two months after concussion followed by a second fMRI with breath-hold challenge one year later. CVR was expressed as the percent change of BOLD signals per unit time of breath-hold. Main outcomes In comparison with CVR measurement of normal control subjects, statistical maps of CVR revealed substantial neurovascular deficits and hemispheric asymmetry within gray and white matter in the initial breath-hold fMRI scan. Follow-up breath-hold fMRI performed one year post mTBI demonstrated normalization of CVR accompanied with symptomatic recovery. Conclusions CVR may serve as an imaging biomarker to detect subtle deficits in both gray and white matter for individual diagnosis of mTBI. The findings encourage further investigation of hypercapnic fMRI as a diagnostic tool for mTBI. PMID:25384127

  8. Adaptive functional magnetic resonance imaging

    E-print Network

    Yoo, Seung-Schik, 1970-

    2000-01-01

    Functional MRI (fMRI) detects the signal associated with neuronal activation, and has been widely used to map brain functions. Locations of neuronal activation are localized and distributed throughout the brain, however, ...

  9. Lornoxicam characteristically modulates cerebral pain-processing in human volunteers: a functional magnetic resonance imaging study

    Microsoft Academic Search

    I. H. Lorenz; K. Egger; H. Schubert; C. Schnurer; W. Tiefenthaler; M. Hohlrieder; M. F. Schocke; C. Kremser; R. Esterhammer; A. Ischebeck; P. L. Moser; C. Kolbitsch

    2008-01-01

    Background. Lornoxicam like other non-steroidal anti-inflammatory drugs (NSAIDs) is widely used for postoperative pain therapy. Evaluation of the effect of lornoxicam on cerebral processing of surgical pain was thus the aim of the present functional magnetic resonance imaging (fMRI) study. Methods. An fMRI-compatible pain model that mimics surgical pain was used to induce pain rated 4-5 on a visual analogue

  10. Functional Magnetic Resonance Imaging of Motor Activation in the Human Cervical Spinal Cord

    Microsoft Academic Search

    Takashi Yoshizawa; Tadao Nose; Gregory J. Moore; Laurel O. Sillerud

    1996-01-01

    Functional magnetic resonance imaging (fMRI) at 1.5 T of a 30-mm segment of the human spinal cord, centered at the seventh cervical cord segment, showed mean blood-oxygenation-dependent contrast changes in image intensity of 4.8% associated with a unilateral hand-closing task in normal human volunteers. The observed locale of activation in the ipsilateral intermediate and ventral gray matter of the cervical

  11. Magnetic resonance neurography: technical considerations.

    PubMed

    Chhabra, Avneesh; Flammang, Aaron; Padua, Abraham; Carrino, John A; Andreisek, Gustav

    2014-02-01

    Proper performance of magnetic resonance neurography (MRN) is essential not only to make the examination easier to interpret but also for its accurate evaluation. This article outlines the technical considerations of MRN, various imaging pulse sequences available on current scanners, as well as their relative advantages and disadvantages. In addition, a guide to the optimal use of high-resolution and high-contrast MRN technique is provided, which will aid clinicians in attaining a good-quality examination. PMID:24210313

  12. Graph-partitioned spatial priors for functional magnetic resonance images.

    PubMed

    Harrison, L M; Penny, W; Flandin, G; Ruff, C C; Weiskopf, N; Friston, K J

    2008-12-01

    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, L.M., Penny, W., Daunizeau, J., and Friston, K.J. (2008). Diffusion-based spatial priors for functional magnetic resonance images. NeuroImage.] 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 (1 mm(3)) 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 high-resolution fMRI data presented here had greatest evidence for the graph partitioned anisotropic model, which was best able to preserve fine functional detail. PMID:18790064

  13. Bistable electron magnetic resonance in solids

    Microsoft Academic Search

    Didier Gourier; Laurent Binet; Olivier Guillot-Noël

    2004-01-01

    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

  14. Wide-range nuclear magnetic resonance detector

    NASA Technical Reports Server (NTRS)

    Sturman, J. C.; Jirberg, R. J.

    1972-01-01

    Compact and easy to use solid state nuclear magnetic resonance detector is designed for measuring field strength to 20 teslas in cryogenically cooled magnets. Extremely low noise and high sensitivity make detector applicable to nearly all types of analytical nuclear magnetic resonance measurements and can be used in high temperature and radiation environments.

  15. Using fMRI to Study Recovery from Acquired Dysphasia

    Microsoft Academic Search

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

    2000-01-01

    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

  16. Optically Detected Scanned Probe Magnetic Resonance Imaging

    NASA Astrophysics Data System (ADS)

    Wolfe, Christopher; Bhallamudi, Vidya; Wang, Hailong; Du, Chunhui; Manuilov, Sergei; Adur, Rohan; Yang, Fengyuan; Hammel, P. Chris

    2014-03-01

    Magnetic resonance is a powerful tool for studying magnetic properties and dynamics of spin systems. Scanned magnetic probes can induce spatially localized resonance due to the strong magnetic field and gradient near the magnetic tip., Nitrogen vacancy centers (NV) in diamond provide a sensitive means of measuring magnetic fields at the nanoscale. We report preliminary results towards using the high sensitivity of NV detection with a scanned magnetic probe to study local magnetic phenomena. This work is supported by the Center for Emergent Materials at The Ohio State University, a NSF Materials Research Science and Engineering Center (DMR-0820414).

  17. Magnetic resonance imaging of acquired cardiac disease.

    PubMed Central

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

    1996-01-01

    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 PMID:8792545

  18. Functional magnetic resonance imaging blood oxygenation level-dependent signal and magnetoencephalography evoked responses yield different neural functionality in reading.

    PubMed

    Vartiainen, Johanna; Liljeström, Mia; Koskinen, Miika; Renvall, Hanna; Salmelin, Riitta

    2011-01-19

    It is often implicitly assumed that the neural activation patterns revealed by hemodynamic methods, such as functional magnetic resonance imaging (fMRI), and electrophysiological methods, such as magnetoencephalography (MEG) and electroencephalography (EEG), are comparable. In early sensory processing that seems to be the case, but the assumption may not be correct in high-level cognitive tasks. For example, MEG and fMRI literature of single-word reading suggests differences in cortical activation, but direct comparisons are lacking. Here, while the same human participants performed the same reading task, analysis of MEG evoked responses and fMRI blood oxygenation level-dependent (BOLD) signals revealed marked functional and spatial differences in several cortical areas outside the visual cortex. Divergent patterns of activation were observed in the frontal and temporal cortex, in accordance with previous separate MEG and fMRI studies of reading. Furthermore, opposite stimulus effects in the MEG and fMRI measures were detected in the left occipitotemporal cortex: MEG evoked responses were stronger to letter than symbol strings, whereas the fMRI BOLD signal was stronger to symbol than letter strings. The EEG recorded simultaneously during MEG and fMRI did not indicate neurophysiological differences that could explain the observed functional discrepancies between the MEG and fMRI results. Acknowledgment of the complementary nature of hemodynamic and electrophysiological measures, as reported here in a cognitive task using evoked response analysis in MEG and BOLD signal analysis in fMRI, represents an essential step toward an informed use of multimodal imaging that reaches beyond mere combination of location and timing of neural activation. PMID:21248130

  19. Gastric distention induced functional magnetic resonance signal changes in the rodent brain.

    PubMed

    Min, D K; Tuor, U I; Chelikani, P K

    2011-04-14

    Investigating the localization of gastric sensation within the brain is important for understanding the neural correlates of satiety. Previous rodent studies have identified the brain-stem and hypothalamus as key mediators of gastric distention-induced satiation. Although, recent blood oxygen level-dependent functional magnetic resonance imaging (BOLD fMRI) studies in humans have identified a role for higher cortico-limbic structures in mediating the satiation effects of gastric distention, the role of these regions in rodents remains to be characterized. We determined the effects of gastric distention on global spatio-temporal BOLD fMRI signal changes in the rodent brain. Brain images were acquired with a high resolution 9.4 T magnet during gastric distention with continuous monitoring of blood pressure in adult male Sprague Dawley rats (n=8-10). Distention of the stomach with an intragastric balloon, at rates which mimicked the rate of consumption and emptying of a mixed nutrient liquid meal, resulted in robust reduction in food intake and increase in blood pressure. Gastric distention increased BOLD fMRI activity within homeostatic regions such as the hypothalamus and nucleus tractus solitarius, as well as non homeostatic regions including the hippocampus, amygdala, thalamus, cerebellum and the cortex (cingulate, insular, motor and sensory cortices). Further, the increase in BOLD fMRI activity following distention was strongly correlated to an increase in blood pressure. These results indicate that gastric distention, mimicking the rate of intake and emptying of a liquid meal, increases BOLD fMRI activity in both homeostatic and non homeostatic brain circuits which regulate food intake, and that these BOLD fMRI signal changes may in part be attributable to transient increases in blood pressure. PMID:21284950

  20. Brain Magnetic Resonance Spectroscopy Classifiers

    Microsoft Academic Search

    Susana Oliveira; Jaime Rocha; Victor Alves

    2010-01-01

    \\u000a During the last decade, the Magnetic Resonance Spectroscopy modality has become an integrant part of the diagnostic routine.\\u000a However, the visual interpretation of these spectra is difficult and few clinicians are trained to use the technique. In this\\u000a study, sixty-eight spectra obtained from twenty-two multi-voxel spectroscopies were classified using three well-known classification\\u000a algorithms: K-Nearest Neighbors (KNN), Decision Trees and Naïve

  1. Tunable Magnetic Resonance in Microwave Spintronics Devices

    NASA Technical Reports Server (NTRS)

    Chen, Yunpeng; Fan, Xin; Xie, Yungsong; Zhou, Yang; Wang, Tao; Wilson, Jeffrey D.; Simons, Rainee N.; Chui, Sui-Tat; Xiao, John Q.

    2015-01-01

    Magnetic resonance is one of the key properties of magnetic materials for the application of microwave spintronics devices. The conventional method for tuning magnetic resonance is to use an electromagnet, which provides very limited tuning range. Hence, the quest for enhancing the magnetic resonance tuning range without using an electromagnet has attracted tremendous attention. In this paper, we exploit the huge exchange coupling field between magnetic interlayers, which is on the order of 4000 Oe and also the high frequency modes of coupled oscillators to enhance the tuning range. Furthermore, we demonstrate a new scheme to control the magnetic resonance frequency. Moreover, we report a shift in the magnetic resonance frequency as high as 20 GHz in CoFe-based tunable microwave spintronics devices, which is 10X higher than conventional methods.

  2. Society for Cardiovascular Magnetic Resonance guidelines for reporting cardiovascular magnetic resonance examinations

    PubMed Central

    Hundley, W Gregory; Bluemke, David; Bogaert, Jan G; Friedrich, Matthias G; Higgins, Charles B; Lawson, Mark A; McConnell, Michael V; Raman, Subha V; van Rossum, Albert C; Flamm, Scott; Kramer, Christopher M; Nagel, Eike; Neubauer, Stefan

    2009-01-01

    These reporting guidelines are recommended by the Society for Cardiovascular Magnetic Resonance (SCMR) to provide a framework for healthcare delivery systems to disseminate cardiac and vascular imaging findings related to the performance of cardiovascular magnetic resonance (CMR) examinations. PMID:19257889

  3. Introduction to Nuclear Magnetic Resonance

    NASA Technical Reports Server (NTRS)

    Manatt, Stanley L.

    1985-01-01

    The purpose of this paper is to try to give a short overview of what the status is on nuclear magnetic resonance (NMR). It's a subject where one really has to spend some time to look at the physics in detail to develop a proper working understanding. I feel it's not appropriate to present to you density matrices, Hamiltonians of all sorts, and differential equations representing the motion of spins. I'm really going to present some history and status, and show a few very simple concepts involved in NMR. It is a form of radio frequency spectroscopy and there are a great number of nuclei that can be studied very usefully with the technique. NMR requires a magnet, a r.f. transmitter/receiver system, and a data acquisition system.

  4. Nitinol in magnetic resonance imaging.

    PubMed

    Melzer; Michitsch; Konak; Schaefers; Bertsch, Th

    2004-08-01

    Surgical and interventional instruments as well as implants can cause significant magnetic resonance image (MRI) artifacts. The artifacts can be used to visualize instruments, cannulae, guide wires, catheters during interventional MRI and Nitinol devices have proven to be useful for MRI procedures. Diagnostic imaging is often compromised in the area of an implant. Complete vanishing of signals occurs in close proximity or inside implants. The paper presents a fundamental evaluation of MRI artifact of Nitinol devices such as Stents, Vena Cava Filter, heart defect closure devices, cannulae, guide wire, localizer, anastomosis device, etc. in a 1.0 Tesla magnetic field. The American Society for Testing Materials (ASTM) recommendations for selection of sequences and test setup were used but the results of this paper are not sufficient for FDA approval. PMID:16754135

  5. Combining functional magnetic resonance imaging with transcranial electrical stimulation

    PubMed Central

    Saiote, Catarina; Turi, Zsolt; Paulus, Walter; Antal, Andrea

    2013-01-01

    Transcranial electrical stimulation (tES) is a neuromodulatory method with promising potential for basic research and as a therapeutic tool. The most explored type of tES is transcranial direct current stimulation (tDCS), but also transcranial alternating current stimulation (tACS) and transcranial random noise stimulation (tRNS) have been shown to affect cortical excitability, behavioral performance and brain activity. Although providing indirect measure of brain activity, functional magnetic resonance imaging (fMRI) can tell us more about the global effects of stimulation in the whole brain and what is more, on how it modulates functional interactions between brain regions, complementing what is known from electrophysiological methods such as measurement of motor evoked potentials. With this review, we aim to present the studies that have combined these techniques, the current approaches and discuss the results obtained so far. PMID:23935578

  6. Review of nuclear magnetic resonance magnet for oil well logging

    Microsoft Academic Search

    Yiming Zhang; Pingchou Xia; Yunjia Yu

    2000-01-01

    Compared with the magnet of Nuclear Magnetic Resonance (NMR) Spectrometer that of Nuclear Magnetic Resonance Oil Well Logging is faced with some special difficulties. This paper begins with the explanation of these special difficulties, and then analyzes the main known borehole NMR logging apparatuses through strict calculations. Finally, this paper gives some useful clues to solve those problems existing in

  7. Abnormal Brain Activation in Excoriation (Skin Picking) Disorder: Evidence from an Executive Planning fMRI Study

    E-print Network

    Odlaug, Brian L.; Hampshire, Adam; Chamberlain, Samuel R.; Grant, Jon E.

    2015-01-01

    and 15 matched healthy controls undertook an executive planning task (Tower of London) during functional Magnetic Resonance Imaging (fMRI). Activation during planning was compared between groups using region of interest and whole-brain permutation cluster...

  8. Exploring the neural basis of cognition: multi-modal links between human fMRI and macaque neurophysiology

    Microsoft Academic Search

    Kiyoshi Nakahara; Yusuke Adachi; Takahiro Osada; Yasushi Miyashita

    2006-01-01

    Although functional magnetic resonance imaging (fMRI) with sophisticated behavioral paradigms has enabled the investigation of increasingly higher-level cognitive functions in humans, these studies seem to lose touch with neurophysiological studies in macaque monkeys. The application of fMRI and other MRI-based techniques to macaque brains allows studies in the two species to be linked. fMRI in human and macaque subjects using

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

    Microsoft Academic Search

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

    2008-01-01

    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

  10. Advances in mechanical detection of magnetic resonance

    PubMed Central

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

    2008-01-01

    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. PMID:18266413

  11. MAGNETIC RESONANCE ELASTOGRAPHY: A REVIEW

    PubMed Central

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

    2011-01-01

    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. PMID:20544947

  12. Regression Models for Identifying Noise Sources in Magnetic Resonance Images.

    PubMed

    Zhu, Hongtu; Li, Yimei; Ibrahim, Joseph G; Shi, Xiaoyan; An, Hongyu; Chen, Yashen; Gao, Wei; Lin, Weili; Rowe, Daniel B; Peterson, Bradley S

    2009-06-01

    Stochastic noise, susceptibility artifacts, magnetic field and radiofrequency inhomogeneities, and other noise components in magnetic resonance images (MRIs) can introduce serious bias into any measurements made with those images. We formally introduce three regression models including a Rician regression model and two associated normal models to characterize stochastic noise in various magnetic resonance imaging modalities, including diffusion-weighted imaging (DWI) and functional MRI (fMRI). Estimation algorithms are introduced to maximize the likelihood function of the three regression models. We also develop a diagnostic procedure for systematically exploring MR images to identify noise components other than simple stochastic noise, and to detect discrepancies between the fitted regression models and MRI data. The diagnostic procedure includes goodness-of-fit statistics, measures of influence, and tools for graphical display. The goodness-of-fit statistics can assess the key assumptions of the three regression models, whereas measures of influence can isolate outliers caused by certain noise components, including motion artifacts. The tools for graphical display permit graphical visualization of the values for the goodness-of-fit statistic and influence measures. Finally, we conduct simulation studies to evaluate performance of these methods, and we analyze a real dataset to illustrate how our diagnostic procedure localizes subtle image artifacts by detecting intravoxel variability that is not captured by the regression models. PMID:19890478

  13. A neural correlate of visceral emotional responses: evidence from fMRI of the thoracic spinal cord

    E-print Network

    Smith, Stephen D.

    A neural correlate of visceral emotional responses: evidence from fMRI of the thoracic spinal cord Functional magnetic resonance imaging (fMRI) of thoracic spinal cord neurons was used to examine the neural; functional MRI; spinal cord; thoracic spinal cord; emotion A core feature of emotional experience

  14. Increased amygdala response to masked emotional faces in depressed subjects resolves with antidepressant treatment: an fMRI study

    Microsoft Academic Search

    Yvette I. Sheline; Deanna M. Barch; Julie M. Donnelly; John M. Ollinger; Abraham Z. Snyder; Mark A. Mintun

    2001-01-01

    Background: The amygdala has a central role in processing emotions, particularly fear. During functional magnetic resonance imaging (fMRI) amygdala activation has been demonstrated outside of conscious awareness using masked emotional faces.Methods: We applied the masked faces paradigm to patients with major depression (n = 11) and matched control subjects (n = 11) during fMRI to compare amygdala activation in response

  15. Electron Paramagnetic Resonance -- Nuclear Magnetic Resonance Three Axis Vector Magnetometer

    NASA Astrophysics Data System (ADS)

    Bulatowicz, Michael; Clark, Philip; Griffith, Robert; Larsen, Michael; Mirijanian, James

    2012-06-01

    The Northrop Grumman Corporation is leveraging the technology developed for the Nuclear Magnetic Resonance Gyroscope (NMRG) to build a combined Electron Paramagnetic Resonance -- Nuclear Magnetic Resonance (EPR-NMR) magnetometer. The EPR-NMR approach provides a high bandwidth and high sensitivity simultaneous measurement of all three vector components of the magnetic field averaged over the small volume of the sensor's one vapor cell. This poster will describe the history, operational principles, and design basics of the EPR-NMR magnetometer including an overview of the NSD designs developed and demonstrated to date. General performance results will also be presented.

  16. Functional Magnetic Resonance Imaging and Pediatric Anxiety

    ERIC Educational Resources Information Center

    Pine, Daniel S.; Guyer, Amanda E.; Leibenluft, Ellen; Peterson, Bradley S.; Gerber, Andrew

    2008-01-01

    The use of functional magnetic resonance imaging in investigating pediatric anxiety disorders is studied. Functional magnetic resonance imaging can be utilized in demonstrating parallels between the neural architecture of difference in anxiety of humans and the neural architecture of attention-orienting behavior in nonhuman primates or rodents.…

  17. Magnetic resonance sees lesions of multiple sclerosis

    SciTech Connect

    Ziporyn, T.

    1985-02-15

    The value of nuclear magnetic resonance imaging in the diagnosis and quantitation of the progression of multiple sclerosis is discussed. Magnetic resonance imaging generates images that reflect differential density and velocity of hydrogen nuclei between cerebral gray and white matter, as well as between white matter and pathological lesions of the disease.

  18. Graph-partitioned spatial priors for functional magnetic resonance images

    PubMed Central

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

    2009-01-01

    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. PMID:18790064

  19. Magnetic Resonance Imaging of Electrolysis.

    PubMed Central

    Meir, Arie; Hjouj, Mohammad; Rubinsky, Liel; Rubinsky, Boris

    2015-01-01

    This study explores the hypothesis that Magnetic Resonance Imaging (MRI) can image the process of electrolysis by detecting pH fronts. The study has relevance to real time control of cell ablation with electrolysis. To investigate the hypothesis we compare the following MR imaging sequences: T1 weighted, T2 weighted and Proton Density (PD), with optical images acquired using pH-sensitive dyes embedded in a physiological saline agar solution phantom treated with electrolysis and discrete measurements with a pH microprobe. We further demonstrate the biological relevance of our work using a bacterial E. Coli model, grown on the phantom. The results demonstrate the ability of MRI to image electrolysis produced pH changes in a physiological saline phantom and show that these changes correlate with cell death in the E. Coli model grown on the phantom. The results are promising and invite further experimental research. PMID:25659942

  20. Calibrated FMRI.

    PubMed

    Hoge, Richard D

    2012-08-15

    Functional magnetic resonance imaging with blood oxygenation level-dependent (BOLD) contrast has had a tremendous influence on human neuroscience in the last twenty years, providing a non-invasive means of mapping human brain function with often exquisite sensitivity and detail. However the BOLD method remains a largely qualitative approach. While the same can be said of anatomic MRI techniques, whose clinical and research impact has not been diminished in the slightest by the lack of a quantitative interpretation of their image intensity, the quantitative expression of BOLD responses as a percent of the baseline T2*- weighted signal has been viewed as necessary since the earliest days of fMRI. Calibrated MRI attempts to dissociate changes in oxygen metabolism from changes in blood flow and volume, the latter three quantities contributing jointly to determine the physiologically ambiguous percent BOLD change. This dissociation is typically performed using a "calibration" procedure in which subjects inhale a gas mixture containing small amounts of carbon dioxide or enriched oxygen to produce changes in blood flow and BOLD signal which can be measured under well-defined hemodynamic conditions. The outcome is a calibration parameter M which can then be substituted into an expression providing the fractional change in oxygen metabolism given changes in blood flow and BOLD signal during a task. The latest generation of calibrated MRI methods goes beyond fractional changes to provide absolute quantification of resting-state oxygen consumption in micromolar units, in addition to absolute measures of evoked metabolic response. This review discusses the history, challenges, and advances in calibrated MRI, from the personal perspective of the author. PMID:22369993

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

    Microsoft Academic Search

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

    2009-01-01

    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

  2. Neural substrates of Hanja (Logogram) and Hangul (Phonogram) character readings by functional magnetic resonance imaging.

    PubMed

    Cho, Zang-Hee; Kim, Nambeom; Bae, Sungbong; Chi, Je-Geun; Park, Chan-Woong; Ogawa, Seiji; Kim, Young-Bo

    2014-10-01

    The two basic scripts of the Korean writing system, Hanja (the logography of the traditional Korean character) and Hangul (the more newer Korean alphabet), have been used together since the 14th century. While Hanja character has its own morphemic base, Hangul being purely phonemic without morphemic base. These two, therefore, have substantially different outcomes as a language as well as different neural responses. Based on these linguistic differences between Hanja and Hangul, we have launched two studies; first was to find differences in cortical activation when it is stimulated by Hanja and Hangul reading to support the much discussed dual-route hypothesis of logographic and phonological routes in the brain by fMRI (Experiment 1). The second objective was to evaluate how Hanja and Hangul affect comprehension, therefore, recognition memory, specifically the effects of semantic transparency and morphemic clarity on memory consolidation and then related cortical activations, using functional magnetic resonance imaging (fMRI) (Experiment 2). The first fMRI experiment indicated relatively large areas of the brain are activated by Hanja reading compared to Hangul reading. The second experiment, the recognition memory study, revealed two findings, that is there is only a small difference in recognition memory for semantic transparency, while for the morphemic clarity was much larger between Hanja and Hangul. That is the morphemic clarity has significantly more effect than semantic transparency on recognition memory when studies by fMRI in correlation with behavioral study. PMID:25368497

  3. 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

    Blackman, Graham A.; Hall, Deborah A.

    2011-01-01

    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…

  4. 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

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

    1999-01-01

    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-

  5. Stepped Impedance Resonators for High Field Magnetic Resonance Imaging

    PubMed Central

    Akgun, Can E.; DelaBarre, Lance; Yoo, Hyoungsuk; Sohn, Sung-Min; Snyder, Carl J.; Adriany, Gregor; Ugurbil, Kamil; Gopinath, Anand; Vaughan, J. Thomas

    2014-01-01

    Multi-element volume radio-frequency (RF) coils are an integral aspect of the growing field of high field magnetic resonance imaging (MRI). In these systems, a popular volume coil of choice has become the transverse electromagnetic (TEM) multi-element transceiver coil consisting of microstrip resonators. In this paper, to further advance this design approach, a new microstrip resonator strategy in which the transmission line is segmented into alternating impedance sections referred to as stepped impedance resonators (SIRs) is investigated. Single element simulation results in free space and in a phantom at 7 tesla (298 MHz) demonstrate the rationale and feasibility of the SIR design strategy. Simulation and image results at 7 tesla in a phantom and human head illustrate the improvements in transmit magnetic field, as well as, RF efficiency (transmit magnetic field versus SAR) when two different SIR designs are incorporated in 8-element volume coil configurations and compared to a volume coil consisting of microstrip elements. PMID:23508243

  6. Role of Ongoing, Intrinsic Activity of Neuronal Populations for Quantitative Neuroimaging of Functional Magnetic Resonance Imaging–Based Networks

    PubMed Central

    Herman, Peter; Sanganahalli, Basavaraju G.; Coman, Daniel; Blumenfeld, Hal; Rothman, Douglas L.

    2011-01-01

    Abstract A primary objective in neuroscience is to determine how neuronal populations process information within networks. In humans and animal models, functional magnetic resonance imaging (fMRI) is gaining increasing popularity for network mapping. Although neuroimaging with fMRI—conducted with or without tasks—is actively discovering new brain networks, current fMRI data analysis schemes disregard the importance of the total neuronal activity in a region. In task fMRI experiments, the baseline is differenced away to disclose areas of small evoked changes in the blood oxygenation level-dependent (BOLD) signal. In resting-state fMRI experiments, the spotlight is on regions revealed by correlations of tiny fluctuations in the baseline (or spontaneous) BOLD signal. Interpretation of fMRI-based networks is obscured further, because the BOLD signal indirectly reflects neuronal activity, and difference/correlation maps are thresholded. Since the small changes of BOLD signal typically observed in cognitive fMRI experiments represent a minimal fraction of the total energy/activity in a given area, the relevance of fMRI-based networks is uncertain, because the majority of neuronal energy/activity is ignored. Thus, another alternative for quantitative neuroimaging of fMRI-based networks is a perspective in which the activity of a neuronal population is accounted for by the demanded oxidative energy (CMRO2). In this article, we argue that network mapping can be improved by including neuronal energy/activity of both the information about baseline and small differences/fluctuations of BOLD signal. Thus, total energy/activity information can be obtained through use of calibrated fMRI to quantify differences of ?CMRO2 and through resting-state positron emission tomography/magnetic resonance spectroscopy measurements for average CMRO2. PMID:22433047

  7. Magnetic resonance in multilayer Gd\\/Si\\/Co magnetic films

    Microsoft Academic Search

    G. S. Patrin; V. O. Vas’kovskii; A. V. Svalov; E. V. Eremin; M. A. Panova; V. N. Vasil’ev

    2006-01-01

    The magnetic properties of multilayer Gd\\/Si\\/Co magnetic films are experimentally studied by electron magnetic resonance and\\u000a analyzed theoretically. The introduction of a semiconductor silicon interlayer is found to substantially affect the magnetic\\u000a interlayer coupling and the magnetic dynamics of the system. The interlayer coupling is shown to be ferromagnetic for the\\u000a (Gd\\/Si)n films and to be antiferromagnetic for the (Gd\\/Si\\/Co\\/Si)n

  8. Artifacts in magnetic resonance imaging.

    PubMed

    Krupa, Katarzyna; Bekiesi?ska-Figatowska, Monika

    2015-01-01

    Artifacts in magnetic resonance imaging and foreign bodies within the patient's body may be confused with a pathology or may reduce the quality of examinations. Radiologists are frequently not informed about the medical history of patients and face postoperative/other images they are not familiar with. A gallery of such images was presented in this manuscript. A truncation artifact in the spinal cord could be misinterpreted as a syrinx. Motion artifacts caused by breathing, cardiac movement, CSF pulsation/blood flow create a ghost artifact which can be reduced by patient immobilization, or cardiac/respiratory gating. Aliasing artifacts can be eliminated by increasing the field of view. An artificially hyperintense signal on FLAIR images can result from magnetic susceptibility artifacts, CSF/vascular pulsation, motion, but can also be found in patients undergoing MRI examinations while receiving supplemental oxygen. Metallic and other foreign bodies which may be found on and in patients' bodies are the main group of artifacts and these are the focus of this study: e.g. make-up, tattoos, hairbands, clothes, endovascular embolization, prostheses, surgical clips, intraorbital and other medical implants, etc. Knowledge of different types of artifacts and their origin, and of possible foreign bodies is necessary to eliminate them or to reduce their negative influence on MR images by adjusting acquisition parameters. It is also necessary to take them into consideration when interpreting the images. Some proposals of reducing artifacts have been mentioned. Describing in detail the procedures to avoid or limit the artifacts would go beyond the scope of this paper but technical ways to reduce them can be found in the cited literature. PMID:25745524

  9. Automated nuclear magnetic resonance analysis

    SciTech Connect

    Snoddy, M.L.; Mount, H.B., II.

    1989-12-05

    This patent describes an apparatus for oil and gas exploration by nuclear magnetic resonance (NMR) analyses of sections of core. It comprises: NMR analysis means for NMR analysis of a portion of core positioned in a probe zone thereof, the NMR means having an inlet side and an outlet side; beltless drive means for engaging the drive engaging portion of a core trough comprising a receptacle portion for receiving a section of core and a drive engaging portion for engaging drive means and for supporting the core trough and for positioning portions of a core supported in the core trough in the target zone of NMR analysis means and for causing successive troughs supporting core sequentially to enter the inlet side of NMR means and after NMR analysis to exit the outlet side; and controller means for causing the drive means to position successive portions of supported core in the target zone and for causing NMR analysis means to generate a measure of NMR response of such positioned successive portions of core and for causing successive troughs supporting core to sequentially enter the inlet side of NMR analysis means and to exit the outlet side.

  10. 1076 IEEE TRANSACTIONS ON MEDICAL IMAGING, VOL. 30, NO. 5, MAY 2011 A Data-Driven Sparse GLM for fMRI Analysis Using

    E-print Network

    -driven functional magnetic resonance imaging (fMRI) analysis, K-SVD, minimum description length (MDL) principle, functionally organized and integrated neural hemodynamics. Furthermore, a minimum description length (MDL

  11. Semi-blind ICA of fMRI: A method for utilizing hypothesis-derived time courses in a spatial ICA analysis

    Microsoft Academic Search

    V.D. Calhoun; T. Adali; M.C. Stevens; K.A. Kiehl; J.J. Pekar

    2005-01-01

    Independent component analysis (ICA) is a data-driven approach utilizing high-order statistical moments to find maximally independent sources that has found fruitful application in functional magnetic resonance imaging (fMRI). Being a blind source separation technique, ICA does not require any explicit constraints upon the fMRI time courses. However, for some fMRI data analysis applications, such as for the analysis of an

  12. Functional Magnetic Resonance Imaging of Human Visual Cortex during Face Matching: A Comparison with Positron Emission Tomography

    Microsoft Academic Search

    V. P. Clark; K. Keil; J. Ma. Maisog; S. Courtney; L. G. Ungerleider; J. V. Haxby

    1996-01-01

    Cortical areas associated with the perception of faces were identified using functional magnetic resonance imaging (fMRI). T2*-weighted gradient echo, echo-planar MR images were obtained using a modified 1.5-T GE Signa MRI. In all nine subjects studied, performance of a face-matching task was associated with a region of significantly increased MR signal in the ventral occipitotemporal cortex, extending from the inferior

  13. Mental Rotation Studied by Functional Magnetic Resonance Imaging at High Field (4 Tesla): Performance and Cortical Activation

    Microsoft Academic Search

    Georgios A. Tagaris; Seong-Gi Kim; John P. Strupp; Peter Andersen; Kamil U??urbil; Apostolos P. Georgopoulos

    1997-01-01

    We studied the performance and cortical activation patterns during a mental rotation task (Shepard & Metzler, 1971) using functional magnetic resonance imaging (fMlU) at high field (4 Tesla). Twenty-four human subjects were imaged (fMRI group), whereas six additional subjects performed the task without being imaged (control group). All subjects were shown pairs of perspective drawings of 31, objects and asked

  14. Reducing Field Distortion in Magnetic Resonance Imaging

    NASA Technical Reports Server (NTRS)

    Eom, Byeong Ho; Penanen, Konstantin; Hahn, Inseob

    2010-01-01

    A concept for a magnetic resonance imaging (MRI) system that would utilize a relatively weak magnetic field provides for several design features that differ significantly from the corresponding features of conventional MRI systems. Notable among these features are a magnetic-field configuration that reduces (relative to the conventional configuration) distortion and blurring of the image, the use of a superconducting quantum interference device (SQUID) magnetometer as the detector, and an imaging procedure suited for the unconventional field configuration and sensor. In a typical application of MRI, a radio-frequency pulse is used to excite precession of the magnetic moments of protons in an applied magnetic field, and the decaying precession is detected for a short time following the pulse. The precession occurs at a resonance frequency proportional to the strengths of the magnetic field and the proton magnetic moment. The magnetic field is configured to vary with position in a known way; hence, by virtue of the aforesaid proportionality, the resonance frequency varies with position in a known way. In other words, position is encoded as resonance frequency. MRI using magnetic fields weaker than those of conventional MRI offers several advantages, including cheaper and smaller equipment, greater compatibility with metallic objects, and higher image quality because of low susceptibility distortion and enhanced spin-lattice-relaxation- time contrast. SQUID MRI is being developed into a practical MRI method for applied magnetic flux densities of the order of only 100 T

  15. Compact low field magnetic resonance imaging magnet: Design and optimization

    Microsoft Academic Search

    M. Sciandrone; G. Placidi; L. Testa; A. Sotgiu

    2000-01-01

    Magnetic resonance imaging (MRI) is performed with a very large instrument that allows the patient to be inserted into a region of uniform magnetic field. The field is generated either by an electromagnet (resistive or superconductive) or by a permanent magnet. Electromagnets are designed as air cored solenoids of cylindrical symmetry, with an inner bore of 80-100 cm in diameter.

  16. Gradient characterization in magnetic resonance imaging

    E-print Network

    Cheng, Joseph Yitan

    2007-01-01

    Special magnetic resonance (MR) scans, such as spiral imaging and echo-planar imaging, require speed and gradient accuracy while putting high demands on the MR gradient system that may cause gradient distortion. Additionally, ...

  17. International Society for Magnetic Resonance in Medicine

    MedlinePLUS

    ... Centre Information about Toronto Toronto Tours & Sightseeing! Visa Information The International Society for Magnetic Resonance in Medicine is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.

  18. Instrumentation for parallel magnetic resonance imaging

    E-print Network

    Brown, David Gerald

    2007-04-25

    Parallel magnetic resonance (MR) imaging may be used to increase either the throughput or the speed of the MR imaging experiment. As such, parallel imaging may be accomplished either through a "parallelization" of the MR experiment, or by the use...

  19. Ferromagnetic Resonance Imaging with Magnetic Resonance Force Microscopy

    NASA Astrophysics Data System (ADS)

    Pelekhov, Denis

    2009-03-01

    Magnetic resonance force microscopy achieves very high resolution three-dimensional imaging capabilities of magnetic resonance imaging by taking advantage of very high sensitivity mechanical force detection. This enables non-contacting, microscopic studies and imaging of a broad range of materials. As a consequence of the strong interactions between spins, the assumptions underlying conventional MRI are not applicable to FMR imaging. However, using a new approach to localizing the resonant volume in an FMR measurement founded on the strong, nonuniform magnetic field of the micromagnetic probe tip, we have demonstrated scanned probe Ferromagnetic Resonance (FMR) imaging [1]. The scanned probe FMR images obtained in patterned ferromagnetic films are well explained by detailed numerical modeling. In addition to illuminating the mechanisms underlying localized FMR, the model provides the basis for submicron scanned probe FMR imaging of films and buried ferromagnetic elements. This work was supported by the U.S. Department of Energy through Grant No. DE-FG02-03ER46054. [1] ``Local Ferromagnetic Resonance Imaging with Magnetic Resonance Force Microscopy,'' Yu. Obukhov, D.V. Pelekhov, J. Kim, P. Banerjee, I. Martin, E. Nazaretski, R. Movshovich, S. An, T.J. Gramila, S. Batra, and P. C. Hammel, Phys. Rev. Lett. 100(19), 197601 (2008).

  20. Manual of clinical magnetic resonance imaging

    SciTech Connect

    Heiken, J.P.; Glazer, H.S.; Lee, J.K.T.; Murphy, W.A.; Gado, M.

    1986-01-01

    This work is a guide to conducting magnetic resonance imaging (MRI) examinations. The manual presents specific imaging protocols for various MRI examinations of the body. An introductory section describes the physical principles and techniques of magnetic resonance imaging and describes the most commonly encountered artifacts. Guidelines are offered for selecting imaging protocols and conducting examinations of the head, spine, neck, chest, cardiovascular system, abdomen, pelvis, musculoskeletal system, and breast.

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

    ERIC Educational Resources Information Center

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

    2012-01-01

    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…

  2. Generating structure-function correlations by ICA based mapping of activation patterns on co-registered fMRI and FA-DTI data

    Microsoft Academic Search

    S. Mitra; M. O'Boyle; E. Corona; B. Li; F. Afrin; B. Nutter; M. Baker; R. Pal; B. Ghosh; T. Karp

    2008-01-01

    Functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) are noninvasive neuroimaging technologies providing functional mapping of stimulus activated voxels and detailed connectivity structures in the brain, which are traditionally based on simplified linear models. Despite the unique functional and structural representations achievable by fMRI and DTI, respectively, both representations still need validations of the assumptions embedded in the

  3. Optimization of Blocked Designs in fMRI Studies

    ERIC Educational Resources Information Center

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

    2010-01-01

    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…

  4. INDEPENDENT COMPONENT ANALYSIS OF AUDITORY FMRI RESPONSES

    Microsoft Academic Search

    Fabrizio Esposito; Elia Formisano; Erich Seifritz; Raffaele Elefante; Rainer Goebel; Francesco Di Salle

    2003-01-01

    The basic principles used by the auditory cortex to decipher the sensory streams are less understood than those used by the visual cortex. Based on previous research on animals, functional Magnetic Resonance Imaging (fMRI) responses in the human auditory cortex to simple streams of colored acoustic noise are expected to follow both linear (sustained) and non-linear (transient) spatio-temporal patterns. Analysis

  5. Physiological noise in brainstem FMRI.

    PubMed

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

    2013-01-01

    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

  6. Upsampling to 400-ms resolution for assessing effective connectivity in functional magnetic resonance imaging data with Granger causality.

    PubMed

    McFarlin, Daniel R; Kerr, Deborah L; Nitschke, Jack B

    2013-01-01

    Granger causality analysis of functional magnetic resonance imaging (fMRI) blood-oxygen-level-dependent signal data allows one to infer the direction and magnitude of influence that brain regions exert on one another. We employed a method for upsampling the time resolution of fMRI data that does not require additional interpolation beyond the interpolation that is regularly used for slice-timing correction. The mathematics for this new method are provided, and simulations demonstrate its viability. Using fMRI, 17 snake phobics and 19 healthy controls viewed snake, disgust, and neutral fish video clips preceded by anticipatory cues. Multivariate Granger causality models at the native 2-sec resolution and at the upsampled 400-ms resolution assessed directional associations of fMRI data among 13 anatomical regions of interest identified in prior research on anxiety and emotion. Superior sensitivity was observed for the 400-ms model, both for connectivity within each group and for group differences in connectivity. Context-dependent analyses for the 400-ms multivariate Granger causality model revealed the specific trial types showing group differences in connectivity. This is the first demonstration of effective connectivity of fMRI data using a method for achieving 400-ms resolution without sacrificing accuracy available at 2-sec resolution. PMID:23134194

  7. PTFOS: Flexible and Absorbable Intracranial Electrodes for Magnetic Resonance Imaging

    PubMed Central

    Bonmassar, Giorgio; Fujimoto, Kyoko; Golby, Alexandra J.

    2012-01-01

    Intracranial electrocortical recording and stimulation can provide unique knowledge about functional brain anatomy in patients undergoing brain surgery. This approach is commonly used in the treatment of medically refractory epilepsy. However, it can be very difficult to integrate the results of cortical recordings with other brain mapping modalities, particularly functional magnetic resonance imaging (fMRI). The ability to integrate imaging and electrophysiological information with simultaneous subdural electrocortical recording/stimulation and fMRI could offer significant insight for cognitive and systems neuroscience as well as for clinical neurology, particularly for patients with epilepsy or functional disorders. However, standard subdural electrodes cause significant artifact in MRI images, and concerns about risks such as cortical heating have generally precluded obtaining MRI in patients with implanted electrodes. We propose an electrode set based on polymer thick film organic substrate (PTFOS), an organic absorbable, flexible and stretchable electrode grid for intracranial use. These new types of MRI transparent intracranial electrodes are based on nano-particle ink technology that builds on our earlier development of an EEG/fMRI electrode set for scalp recording. The development of MRI-compatible recording/stimulation electrodes with a very thin profile could allow functional mapping at the individual subject level of the underlying feedback and feed forward networks. The thin flexible substrate would allow the electrodes to optimally contact the convoluted brain surface. Performance properties of the PTFOS were assessed by MRI measurements, finite difference time domain (FDTD) simulations, micro-volt recording, and injecting currents using standard electrocortical stimulation in phantoms. In contrast to the large artifacts exhibited with standard electrode sets, the PTFOS exhibited no artifact due to the reduced amount of metal and conductivity of the electrode/trace ink and had similar electrical properties to a standard subdural electrode set. The enhanced image quality could enable routine MRI exams of patients with intracranial electrode implantation and could also lead to chronic implantation solutions. PMID:22984396

  8. Unwrapping magnetic resonance phase maps with Chebyshev polynomials.

    PubMed

    Langley, Jason; Zhao, Qun

    2009-11-01

    A phase-unwrapping algorithm, based on the method of moments, is introduced in this work. The proposed algorithm expands the phase map in terms of a two-dimensional Chebyshev series. The expansion coefficients are calculated by exploiting the orthogonality of Chebyshev polynomials of the first kind. The performance of the proposed phase-unwrapping algorithm is tested on a synthetic phase map and experimental phase maps of a uniform phantom, a human brain and a mouse torso, all acquired from 3-T magnetic resonance (MR) scanners. To impose additional burdens on the algorithm, we introduced magnetic field inhomogeneities to the phantom and human brain data by an external gradient coil. The proposed phase-unwrapping algorithm is found to perform well on the phantom data set in a low signal-to-noise ratio (SNR) environment and on the synthetic data set. The proposed algorithm is also found to perform well in in vivo data sets of the human brain and mouse torso. Results obtained from the in vivo MR data sets show that the proposed algorithm produced unwrapped phase maps that are nearly identical to those produced by a widely used phase-unwrapping algorithm, PRELUDE 2D in the fMRI Software Library. PMID:19574009

  9. 76 FR 58281 - Magnetic Resonance Imaging Safety; Public Workshop

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-20

    ...factors affecting the safe use of magnetic resonance imaging (MRI) and approaches...the International Society for Magnetic Resonance in Medicine (ISMRM...implants include the static magnetic field, maximum spatial gradient,...

  10. Resting-state FMRI confounds and cleanup

    PubMed Central

    Murphy, Kevin; Birn, Rasmus M.; Bandettini, Peter A.

    2013-01-01

    The goal of resting-state functional magnetic resonance imaging (FMRI) is to investigate the brain’s functional connections by using the temporal similarity between blood oxygenation level dependent (BOLD) signals in different regions of the brain “at rest” as an indicator of synchronous neural activity. Since this measure relies on the temporal correlation of FMRI signal changes between different parts of the brain, any non-neural activity-related process that affects the signals will influence the measure of functional connectivity, yielding spurious results. To understand the sources of these resting-state FMRI confounds, this article describes the origins of the BOLD signal in terms of MR physics and cerebral physiology. Potential confounds arising from motion, cardiac and respiratory cycles, arterial CO2 concentration, blood pressure/cerebral autoregulation, and vasomotion are discussed. Two classes of techniques to remove confounds from resting-state BOLD time series are reviewed: 1) those utilising external recordings of physiology and 2) data-based cleanup methods that only use the resting-state FMRI data itself. Further methods that remove noise from functional connectivity measures at a group level are also discussed. For successful interpretation of resting-state FMRI comparisons and results, noise cleanup is an often over-looked but essential step in the analysis pipeline. PMID:23571418

  11. Target image search using fMRI signals

    NASA Astrophysics Data System (ADS)

    Xiong, Shi; Song, Sutao; Zhan, Yu; Zhang, Jiacai

    2014-03-01

    Recent neural signal decoding studies based on functional magnetic resonance imaging (fMRI) have identified the specific image presenting to the subject from a set of potential images, and some studies extend neural decoding into image reconstruction, i.e. image contents that the subject perceived were decoded from the fMRI signals recorded during the subject looking at images. In this paper, we decoded the target images using fMRI signals and described a target image searching method based on the relationship between target image stimuli and fMRI activity. We recorded fMRI data during a serial visual stimuli image presentation task, some of the stimuli images were target images and the rest images were non-target ones. Our fMRI data analysis results showed that in the serial visual presentation task, target images elicited a stereotypical response in the fMRI, which can be detected by multi-voxel pattern analysis (MVPA). Classifiers designed with support vector machine (SVM) used this response to decipher target images from non-target images. The leave-one-run-out cross-validation showed that we can pick out the target images with a possibility far above the chance level, which indicate that there's a neural signatures correlated with the target image recognition process in the human systems.

  12. Investigation of laser polarized xenon magnetic resonance

    NASA Technical Reports Server (NTRS)

    Walsworth, Ronald L.

    1998-01-01

    Ground-based investigations of a new biomedical diagnostic technology: nuclear magnetic resonance of laser polarized noble gas are addressed. The specific research tasks discussed are: (1) Development of a large-scale noble gas polarization system; (2) biomedical investigations using laser polarized noble gas in conventional (high magnetic field) NMR systems; and (3) the development and application of a low magnetic field system for laser polarized noble gas NMR.

  13. Spin-echo fMRI in humans using high spatial resolutions and high magnetic fields.

    PubMed

    Yacoub, Essa; Duong, Timothy Q; Van De Moortele, Pierre-Francois; Lindquist, Martin; Adriany, Gregor; Kim, Seong-Gi; U?urbil, Kâmil; Hu, Xiaoping

    2003-04-01

    The Hahn spin-echo (HSE)-based BOLD effect at high magnetic fields is expected to provide functional images that originate exclusively from the microvasculature. The blood contribution that dominates HSE BOLD contrast at low magnetic fields (e.g., 1.5 T), and degrades specificity, is highly attenuated at high fields because the apparent T(2) of venous blood in an HSE experiment decreases quadratically with increasing magnetic field. In contrast, the HSE BOLD contrast is believed to arise from the microvasculature and increase supralinearly with the magnetic field strength. In this work we report the results of detailed and quantitative evaluations of HSE BOLD signal changes for functional imaging in the human visual cortex at 4 and 7 T. This study used high spatial resolution, afforded by the increased signal-to-noise ratio (SNR) of higher field strengths and surface coils, to avoid partial volume effects (PVEs), and demonstrated increased contrast-to-noise ratio (CNR) and spatial specificity at the higher field strengths. The HSE BOLD signal changes induced by visual stimulation were predominantly linearly dependent on the echo time (TE). They increased in magnitude almost quadratically in going from 4 to 7 T when the blood contribution was suppressed using Stejskal-Tanner gradients that suppress signals from the blood due to its inhomogeneous flow and higher diffusion constant relative to tissue. The HSE signal changes at 7 T were modeled accurately using a vascular volume of 1.5%, in agreement with the capillary volume of gray matter. Furthermore, high-resolution acquisitions indicate that CNR increased with voxel sizes < 1 mm(3) due to diminishing white matter or cerebrospinal fluid-space vs. gray matter PVEs. It was concluded that the high-field HSE functional MRI (fMRI) signals originated largely from the capillaries, and that the magnitude of the signal changes associated with brain function reached sufficiently high levels at 7 T to make it a useful approach for mapping on the millimeter to submillimeter spatial scale. PMID:12652536

  14. Magnetic Resonance Imaging of Dendrite Currents

    NASA Astrophysics Data System (ADS)

    Jay, William; Dolasinski, Brian; Wijesinghe, Ranjith; Roth, Bradley

    2011-10-01

    The action currents of active dendrites generate their own magnetic field, which can cause the phase of the spins to change. Many investigators have attempted to detect neural and dendritic currents directly using magnetic resonance imaging. Such a measurement of action currents would be remarkable, since it would allow functional imaging of neural activity using the high spatial resolution of MRI and avoid an ill-posed inverse problem to determine the current sources. Measurement of the magnetic field of neural currents would better follow the distribution of neural activity in time and space. Our goal in this presentation is to use the calculated magnetic field of a dendrite to estimate the resulting phase shift in the magnetic resonance signal. We find the phase shift produced by a collection of simultaneously active dendrites is below the threshold for detection using current MRI technology.

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

    Microsoft Academic Search

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

    1999-01-01

    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

  16. Face Prediction from fMRI Data during Movie Stimulus: Strategies for Feature Selection

    Microsoft Academic Search

    Jukka-Pekka Kauppi; Heikki Huttunen; Heikki Korkala; Iiro Jääskeläinen; Mikko Sams; Jussi Tohka

    \\u000a We investigate the suitability of the multi-voxel pattern analysis approach to analyze diverse movie stimulus functional magnetic\\u000a resonance imaging (fMRI) data. We focus on predicting the presence of faces in the drama movie based on the fMRI measurements\\u000a of 12 subjects watching the movie. We pose the prediction as a regression problem where regression coefficients estimated\\u000a from the training data

  17. Presurgical language fMRI in patients with drug-resistant epilepsy: effects of task performance

    Microsoft Academic Search

    Bernd Weber; Jorg Wellmer; Simone Schur; Vera Dinkelacker; Jurgen Ruhlmann; Florian Mormann; Nikolai Axmacher; Christian E. Elger; Guillen Fernandez

    2006-01-01

    PURPOSE: To determine whether language functional magnetic resonance imaging (fMRI) before epilepsy surgery can be similarly interpreted in patients with greatly different performance levels. METHODS: An fMRI paradigm using a semantic decision task with performance control and a perceptual control task was applied to 226 consecutive patients with drug-resistant localization-related epilepsy during their presurgical evaluations. The volume of activation and

  18. High-resolution mapping of iso-orientation columns by fMRI

    Microsoft Academic Search

    Dae-Shik Kim; Timothy Q. Duong; Seong-Gi Kim

    2000-01-01

    Blood-oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) is an important tool for localizing brain functions in vivo . However, the ability of BOLD fMRI to map cortical columnar structures is highly controversial, as the ultimate functional specificity of BOLD remains unknown. Here we report a biphasic BOLD response to visual stimulation in the primary visual cortex of cats. In

  19. Magnetic resonance in multilayer Gd/Si/Co magnetic films

    SciTech Connect

    Patrin, G. S. [Russian Academy of Sciences, Kirenskii Institute of Physics, Siberian Division (Russian Federation)], E-mail: patrin@iph.krasn.ru; Vas'kovskii, V. O.; Svalov, A. V. [Ural State University (Russian Federation); Eremin, E. V.; Panova, M. A.; Vasil'ev, V. N. [Russian Academy of Sciences, Kirenskii Institute of Physics, Siberian Division (Russian Federation)

    2006-01-15

    The magnetic properties of multilayer Gd/Si/Co magnetic films are experimentally studied by electron magnetic resonance and analyzed theoretically. The introduction of a semiconductor silicon interlayer is found to substantially affect the magnetic interlayer coupling and the magnetic dynamics of the system. The interlayer coupling is shown to be ferromagnetic for the (Gd/Si){sub n} films and to be antiferromagnetic for the (Gd/Si/Co/Si){sub n} films. The temperature dependences of the exchange parameters and the gyromagnetic ratios are determined. Possible mechanisms responsible for the formation of the interlayer coupling are discussed.

  20. Magnetic resonance signal moment determination using the Earth's magnetic field

    NASA Astrophysics Data System (ADS)

    Fridjonsson, E. O.; Creber, S. A.; Vrouwenvelder, J. S.; Johns, M. L.

    2015-03-01

    We demonstrate a method to manipulate magnetic resonance data such that the moments of the signal spatial distribution are readily accessible. Usually, magnetic resonance imaging relies on data acquired in so-called k-space which is subsequently Fourier transformed to render an image. Here, via analysis of the complex signal in the vicinity of the centre of k-space we are able to access the first three moments of the signal spatial distribution, ultimately in multiple directions. This is demonstrated for biofouling of a reverse osmosis (RO) membrane module, rendering unique information and an early warning of the onset of fouling. The analysis is particularly applicable for the use of mobile magnetic resonance spectrometers; here we demonstrate it using an Earth's magnetic field system.

  1. Euclidean resonance in a magnetic field

    E-print Network

    B. Ivlev

    2007-05-19

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

  2. Euclidean resonance in a magnetic field

    SciTech Connect

    Ivlev, B. [Department of Physics and Astronomy and NanoCenter, University of South Carolina, Columbia, South Carolina 29208 (United States) and Instituto de Fisica, Universidad Autonoma de San Luis Potosi, San Luis Potosi, San Luis Potosi, 78000 (Mexico)

    2007-08-15

    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.

  3. Focal renal masses: magnetic resonance imaging

    SciTech Connect

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

    1984-08-01

    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.

  4. Magnetic plasmonic fano resonance at optical frequency.

    PubMed

    Bao, Yanjun; Hu, Zhijian; Li, Ziwei; Zhu, Xing; Fang, Zheyu

    2015-05-01

    Plasmonic Fano resonances are typically understood and investigated assuming electrical mode hybridization. Here we demonstrate that a purely magnetic plasmon Fano resonance can be realized at optical frequency with Au split ring hexamer nanostructure excited by an azimuthally polarized incident light. Collective magnetic plasmon modes induced by the circular electric field within the hexamer and each of the split ring can be controlled and effectively hybridized by designing the size and orientation of each ring unit. With simulated results reproducing the experiment, our suggested configuration with narrow line-shape magnetic Fano resonance has significant potential applications in low-loss sensing and may serves as suitable elementary building blocks for optical metamaterials. PMID:25594885

  5. Magnetic resonance imaging of breast implants.

    PubMed

    Shah, Mala; Tanna, Neil; Margolies, Laurie

    2014-12-01

    Silicone breast implants have significantly evolved since their introduction half a century ago, yet implant rupture remains a common and expected complication, especially in patients with earlier-generation implants. Magnetic resonance imaging is the primary modality for assessing the integrity of silicone implants and has excellent sensitivity and specificity, and the Food and Drug Administration currently recommends periodic magnetic resonance imaging screening for silent silicone breast implant rupture. Familiarity with the types of silicone implants and potential complications is essential for the radiologist. Signs of intracapsular rupture include the noose, droplet, subcapsular line, and linguine signs. Signs of extracapsular rupture include herniation of silicone with a capsular defect and extruded silicone material. Specific sequences including water and silicone suppression are essential for distinguishing rupture from other pathologies and artifacts. Magnetic resonance imaging provides valuable information about the integrity of silicone implants and associated complications. PMID:25463409

  6. Stepped impedance resonators for high-field magnetic resonance imaging.

    PubMed

    Akgun, Can E; DelaBarre, Lance; Yoo, Hyoungsuk; Sohn, Sung-Min; Snyder, Carl J; Adriany, Gregor; Ugurbil, Kamil; Gopinath, Anand; Vaughan, J Thomas

    2014-02-01

    Multi-element volume radio-frequency (RF) coils are an integral aspect of the growing field of high-field magnetic resonance imaging. In these systems, a popular volume coil of choice has become the transverse electromagnetic (TEM) transceiver coil consisting of microstrip resonators. In this paper, to further advance this design approach, a new microstrip resonator strategy in which the transmission line is segmented into alternating impedance sections, referred to as stepped impedance resonators (SIRs), is investigated. Single-element simulation results in free space and in a phantom at 7 T (298 MHz) demonstrate the rationale and feasibility of the SIR design strategy. Simulation and image results at 7 T in a phantom and human head illustrate the improvements in a transmit magnetic field, as well as RF efficiency (transmit magnetic field versus specific absorption rate) when two different SIR designs are incorporated in 8-element volume coil configurations and compared to a volume coil consisting of microstrip elements. PMID:23508243

  7. Magnetic resonance imaging of the knee

    SciTech Connect

    Mink, J.H.; Reicher, M.A.; Crues, J.V.

    1987-01-01

    Introducing a comprehensive, practical guide to the use of magnetic resonance imaging (MRI) in detecting and evaluating knee disorders and planning arthroscopic surgery) This book integrates MRI findings with pertinent anatomy, physiology, and clinical signs to assist radiologists in selecting imaging protocols and interpreting scans. Detailed chapters focus on magnetic resonance imaging of the menisci and ligaments and evaluation of osteonecrosis, osteochondrosis, and osteochondritis. The authors demonstrate the potential of MRI for diagnosing various knee disorders such as arthritis, fractures, popliteal cysts, synovial disease, plicae, popliteal artery aneurysms, tumors, and bone marrow disorders.

  8. Magnetic resonance imaging safety: principles and guidelines.

    PubMed

    Stikova, E

    2012-07-01

    (Full text is available at http://www.manu.edu.mk/prilozi). This paper provides an overview of the published literature regarding magnetic resonance imaging (MRI) safety. It gives basic information about the electromagnetic fields that are generated during the MRI diagnostic procedure, followed by a description of the biological effects of those fields on humans. It concludes with a discussion of the safety issues related to MRI use in clinical practice, highlighting the existing MRI standards and guidelines. Key words: magnetic resonance imaging, biological effects of electromagnetic radiation, MRI standards, safety guidelines. PMID:23037190

  9. Brain activity during simulated deception: an event-related functional magnetic resonance study.

    PubMed

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

    2002-03-01

    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 between deceptive and truthful responses were measured with a 4 Tesla scanner in 18 participants performing the GKT and analyzed using statistical parametric mapping. Increased activity in the anterior cingulate cortex (ACC), the superior frontal gyrus (SFG), and the left premotor, motor, and anterior parietal cortex was specifically associated with deceptive responses. The results indicate that: (a) cognitive differences between deception and truth have neural correlates detectable by fMRI, (b) inhibition of the truthful response may be a basic component of intentional deception, and (c) ACC and SFG are components of the basic neural circuitry for deception. PMID:11848716

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

    PubMed Central

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

    2013-01-01

    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. PMID:23789919

  11. Analytic Programming with fMRI Data: A Quick-Start Guide for Statisticians Using R

    PubMed Central

    Eloyan, Ani; Li, Shanshan; Muschelli, John; Pekar, Jim J.; Mostofsky, Stewart H.; Caffo, Brian S.

    2014-01-01

    Functional magnetic resonance imaging (fMRI) is a thriving field that plays an important role in medical imaging analysis, biological and neuroscience research and practice. This manuscript gives a didactic introduction to the statistical analysis of fMRI data using the R project, along with the relevant R code. The goal is to give statisticians who would like to pursue research in this area a quick tutorial for programming with fMRI data. References of relevant packages and papers are provided for those interested in more advanced analysis. PMID:24586801

  12. MR-eyetracker: a new method for eye movement recording in functional magnetic resonance imaging.

    PubMed

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

    1999-06-01

    We present a method for recording saccadic and pursuit eye movements in the magnetic resonance tomograph designed for visual functional magnetic resonance imaging (fMRI) experiments. To reliably classify brain areas as pursuit or saccade related it is important to carefully measure the actual eye movements. For this purpose, infrared light, created outside the scanner by light-emitting diodes (LEDs), is guided via optic fibers into the head coil and onto the eye of the subject. Two additional fiber optical cables pick up the light reflected by the iris. The illuminating and detecting cables are mounted in a plastic eyepiece that is manually lowered to the level of the eye. By means of differential amplification, we obtain a signal that covaries with the horizontal position of the eye. Calibration of eye position within the scanner yields an estimate of eye position with a resolution of 0.2 degrees at a sampling rate of 1000 Hz. Experiments are presented that employ echoplanar imaging with 12 image planes through visual, parietal and frontal cortex while subjects performed saccadic and pursuit eye movements. The distribution of BOLD (blood oxygen level dependent) responses is shown to depend on the type of eye movement performed. Our method yields high temporal and spatial resolution of the horizontal component of eye movements during fMRI scanning. Since the signal is purely optical, there is no interaction between the eye movement signals and the echoplanar images. This reasonably priced eye tracker can be used to control eye position and monitor eye movements during fMRI. PMID:10382629

  13. Magnetic resonance spectroscopy of perpendicularly magnetized Permalloy multilayer disks

    Microsoft Academic Search

    G. de Loubens; V. V. Naletov; M. Viret; O. Klein; Hervé Hurdequint; J. Ben Youssef; F. Boust; N. Vukadinovic

    2007-01-01

    Using a magnetic resonance force microscope, we compare the ferromagnetic resonance spectra of individual micron size disks with identical diameter, 1 mum, but different layer structures. For a disk composed of a single 43.3-nm-thick Permalloy (Py) layer, the lowest energy mode in the perpendicular configuration is the uniform precession. The higher energy modes are standing spin waves confined along the

  14. A NEW CLUSTERING ALGORITHM FOR SEGMENTATION OF MAGNETIC RESONANCE IMAGES

    E-print Network

    Slatton, Clint

    A NEW CLUSTERING ALGORITHM FOR SEGMENTATION OF MAGNETIC RESONANCE IMAGES By ERHAN GOKCAY which improved the quality of this dissertation. I also wish to thank my wife Didem and my son Tugra . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.1 Magnetic Resonance Image Segmentation

  15. Functional atlas of emotional faces processing: a voxel-based meta-analysis of 105 functional magnetic resonance imaging studies

    PubMed Central

    Fusar-Poli, Paolo; Placentino, Anna; Carletti, Francesco; Landi, Paola; Allen, Paul; Surguladze, Simon; Benedetti, Francesco; Abbamonte, Marta; Gasparotti, Roberto; Barale, Francesco; Perez, Jorge; McGuire, Philip; Politi, Pierluigi

    2009-01-01

    Background Most of our social interactions involve perception of emotional information from the faces of other people. Furthermore, such emotional processes are thought to be aberrant in a range of clinical disorders, including psychosis and depression. However, the exact neurofunctional maps underlying emotional facial processing are not well defined. Methods Two independent researchers conducted separate comprehensive PubMed (1990 to May 2008) searches to find all functional magnetic resonance imaging (fMRI) studies using a variant of the emotional faces paradigm in healthy participants. The search terms were: “fMRI AND happy faces,” “fMRI AND sad faces,” “fMRI AND fearful faces,” “fMRI AND angry faces,” “fMRI AND disgusted faces” and “fMRI AND neutral faces.” We extracted spatial coordinates and inserted them in an electronic database. We performed activation likelihood estimation analysis for voxel-based meta-analyses. Results Of the originally identified studies, 105 met our inclusion criteria. The overall database consisted of 1785 brain coordinates that yielded an overall sample of 1600 healthy participants. Quantitative voxel-based meta-analysis of brain activation provided neurofunctional maps for 1) main effect of human faces; 2) main effect of emotional valence; and 3) modulatory effect of age, sex, explicit versus implicit processing and magnetic field strength. Processing of emotional faces was associated with increased activation in a number of visual, limbic, temporoparietal and prefrontal areas; the putamen; and the cerebellum. Happy, fearful and sad faces specifically activated the amygdala, whereas angry or disgusted faces had no effect on this brain region. Furthermore, amygdala sensitivity was greater for fearful than for happy or sad faces. Insular activation was selectively reported during processing of disgusted and angry faces. However, insular sensitivity was greater for disgusted than for angry faces. Conversely, neural response in the visual cortex and cerebellum was observable across all emotional conditions. Limitations Although the activation likelihood estimation approach is currently one of the most powerful and reliable meta-analytical methods in neuroimaging research, it is insensitive to effect sizes. Conclusion Our study has detailed neurofunctional maps to use as normative references in future fMRI studies of emotional facial processing in psychiatric populations. We found selective differences between neural networks underlying the basic emotions in limbic and insular brain regions. PMID:19949718

  16. Sample spinner for nuclear magnetic resonance spectrometer

    SciTech Connect

    Stejskal, E.O.

    1984-05-01

    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.

  17. Analytical Methods for Characterizing Magnetic Resonance Probes

    PubMed Central

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

    2012-01-01

    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. PMID:22624599

  18. Prenatal magnetic resonance imaging enhances fetal diagnosis

    Microsoft Academic Search

    Theresa M Quinn; Anne M Hubbard; N. Scott Adzick

    1998-01-01

    Background: Ultrasound (US) evaluation of some fetal anomalies provides limited information. Anatomic details that affect prognosis and selection for fetal therapy, such as liver herniation and pulmonary hypoplasia in congenital diaphragmatic hernia (CDH) and airway patency in giant neck masses, may be difficult to delineate using conventional sonographic methods. The authors evaluated the utility of prenatal magnetic resonance imaging (MRI)

  19. Magnetic resonance imaging in acute tendon ruptures

    Microsoft Academic Search

    Richard H. Daffner; Barry L. Riemer; Anthony R. Lupetin; Nilima Dash

    1986-01-01

    The diagnosis of acute tendon ruptures of the extensor mechanism of the knee or the Achilles tendon of the ankle may usually be made by clinical means. Massive soft tissue swelling accompanying these injuries often obscures the findings, however. Magnetic resonance imaging (MRI) can rapidly demonstrate these tendon ruptures. Examples of the use of MRI for quadriceps tendon, and Achilles

  20. Magnetic Resonance Appearance of Normal Inguinal Nodes

    Microsoft Academic Search

    A. C. GREY; B. M. CARRINGTON; P. A. HULSE; R. SWINDELL; W. YATES

    2000-01-01

    AIM: To identify adult inguinal lymph node anatomical subgroups using magnetic resonance imaging (MRI), to derive a normal range for nodal number and size and to describe their morphology.MATERIALS AND METHODS: Eighty-three oncology patients with low stage pelvic tumours had inguinal lymph node assessment by MRI. Nodes were divided into proximal superficial (PS), distal superficial (DS) and deep inguinal (DI)

  1. Nuclear magnetic resonance in rare earth metals

    Microsoft Academic Search

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

    1979-01-01

    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

  2. Magnetic resonance imaging of Morgagni hernia

    Microsoft Academic Search

    Bradford A. Yeager; Gwen E. Guglielmi; Mark L. Schiebler; Warren B. Gefter; Herbert Y. Kressel

    1987-01-01

    A case of a Morgagni hernia is demonstrated by magnetic resonance imaging (MRI). The correct diagnosis was facilitated by the ability to image directly the anteromedial diaphragmatic defect in the coronal and sagittal planes. The findings from MRI, computed tomography, and radiographic studies are correlated.

  3. Proton Magnetic Resonance Spectroscopy of Hydrocephalic Infants

    Microsoft Academic Search

    Sean A. McNatt; J. Gordon McComb; Marvin D. Nelson; Stefan Bluml

    2007-01-01

    Objective: The authors present the first report evaluating neonates with chronic hydrocephalus using proton magnetic resonance spectroscopy (1H MRS). The goals of the study were (1) to determine absolute brain metabolite concentrations in premature infants and neonates with hydrocephalus and age-matched controls, (2) conduct an initial survey of potential biochemical abnormalities of the newborn hydrocephalic brain, and (3) determine whether

  4. Inversion of Magnetic Resonance Sounding data

    Microsoft Academic Search

    U. Yaramanci; M. Hertrich; Hochschule Zürich

    2007-01-01

    In this paper the basics, state of the art, current and future developments considering inversion of Magnetic Resonance Sounding (MRS) data are presented. A very brief account is given about the MRS method as such to an extent for better understanding of inversion and what it relates to. The inversion is introduced in general terms as usual for the geophysical

  5. Quantitative cardiovascular magnetic resonance for molecular imaging

    Microsoft Academic Search

    Patrick M Winter; Shelton D Caruthers; Gregory M Lanza; Samuel A Wickline

    2010-01-01

    Cardiovascular magnetic resonance (CMR) molecular imaging aims to identify and map the expression of important biomarkers on a cellular scale utilizing contrast agents that are specifically targeted to the biochemical signatures of disease and are capable of generating sufficient image contrast. In some cases, the contrast agents may be designed to carry a drug payload or to be sensitive to

  6. Biliary Ascariasis on Magnetic Resonance Cholangiopancreatography

    PubMed Central

    Hashmi, Mohammad A; De, Jevan K

    2009-01-01

    A 17-year-old girl presented with features of biliary obstruction. Magnetic resonance cholangi-pancreatography revealed typical linear signals in common bile duct, which appears like Ascaris lumbricoides. The diagnosis was confirmed by endoscopic removal of the worm. PMID:20300405

  7. Magnetic resonance images of tuberous sclerosis

    Microsoft Academic Search

    Y. Inoue; S. Nakajima; T. Fukuda; Y. Nemoto; M. Shakudo; R. Murata; O. Matsuoka; K. Takemoto; Y. Matsumura; Y. Onoyama

    1988-01-01

    The cerebral lesions in tuberous sclerosis are of three kinds: subependymal nodules, cortical tubers, and cluster of heterotopic cells in the white matter. Understanding of these hamartomas is still incomplete even with modern imaging modalities. Magnetic resonance (MR) images of ten patients with tuberous sclerosis were reviewed and compared to computed tomographic (CT) scans and to the clinical severity of

  8. Magnetic resonance urography in pediatric urology

    Microsoft Academic Search

    Wolfgang H. Cerwinka; J. Damien Grattan-Smith; Andrew J. Kirsch

    2008-01-01

    Purpose of reviewMagnetic resonance urography (MRU) has emerged as a powerful diagnostic tool in the evaluation of the pediatric genitourinary tract. The purpose of this review is to familiarize the reader with the basic techniques, strengths and limitations, as well as the current and potential future applications of MRU in pediatric urology.

  9. Parallel magnetic resonance imaging: characterization and comparison 

    E-print Network

    Rane, Swati Dnyandeo

    2005-11-01

    . Echo Planar Imaging (EPI) . . . . . . . . . . . . 11 b.FastSpinEcho(FSE) ............... 12 c. OtherPulseSequences ............... 14 2. ParallelImaging ..................... 14 III PARALLEL MAGNETIC RESONANCE IMAGING ....... 15 A...-SMASH (VD-AUTO-SMASH) . . 22 H.GRAPPA ........................... 23 I. SPACERIP.......................... 24 J. SingleEchoAcquisition(SEA)................ 24 IV CHARACTERIZATION AND COMPARISON OF PARAL- LEL MRI TECHNIQUES ..................... 26 vi CHAPTER...

  10. Multivariate Strategies in Functional Magnetic Resonance Imaging

    ERIC Educational Resources Information Center

    Hansen, Lars Kai

    2007-01-01

    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.

  11. Magnetic Resonance Force Microscopy Detected Long-Lived Spin Magnetization

    PubMed Central

    Chen, Lei; Longenecker, Jonilyn G.; Moore, Eric W.; Marohn, John A.

    2015-01-01

    Magnetic resonance force microscopy (MRFM), which combines magnetic resonance imaging with scanning probe microscopy together, is capable of performing ultra-sensitive detection of spin magnetization. In an attempt to observe dynamic nuclear polarization (DNP) in an MRFM experiment, which could possibly further improve its sensitivity towards a single proton spin, a film of perdeuterated polystyrene doped with a nitroxide electron-spin probe was prepared. A high-compliance cantilever with a 4 ?m diameter magnetic tip was brought near the film at a temperature of 7.3 K and in a background magnetic field of ~0.6 T. The film was irradiated with 16.7 GHz microwaves while the resulting transient change in cantilever frequency was recorded in real time. In addition to observing the expected prompt change in cantilever frequency due to saturation of the nitroxide’s electron-spin magnetization, we observed a persistent cantilever frequency change. Based on its magnitude, lifetime, and field dependence, we tentatively attribute the persistent signal to polarized deuteron magnetization created via transfer of magnetization from electron spins. Further measurements of the persistent signal’s dependence on the cantilever amplitude and tip-sample separation are presented and explained by the cross-effect DNP mechanism in high magnetic field gradients. PMID:26097251

  12. Musculoskeletal applications of magnetic resonance imaging: Council on Scientific Affairs

    SciTech Connect

    Harms, S.E.; Fisher, C.F.; Fulmer, J.M. (American Medical Association, Chicago, IL (USA))

    1989-11-03

    Magnetic resonance imaging provides superior contrast, resolution, and multiplanar imaging capability, allowing excellent definition of soft-tissue and bone marrow abnormalities. For these reasons, magnetic resonance imaging has become a major diagnostic imaging method for the evaluation of many musculoskeletal disorders. The applications of magnetic resonance imaging for musculoskeletal diagnosis are summarized and examples of common clinical situations are given. General guidelines are suggested for the musculoskeletal applications of magnetic resonance imaging.

  13. Navigational memory functional magnetic resonance imaging: a test for concussion in children.

    PubMed

    Saluja, Rajeet Singh; Chen, Jen-Kai; Gagnon, Isabelle J; Keightley, Michelle; Ptito, Alain

    2015-05-15

    Concussions are high incidence injuries with potentially devastating consequences. Youths are at risk because of a higher threat of repeated injury, and cumulative effects of concussions exist, making accurate diagnosis and follow-up essential. This study examines a navigational memory functional magnetic resonance imaging (fMRI) task to determine whether activation differences exist between children with concussion and uninjured controls. Fifty adolescents were recruited-35 controls and 15 with concussion. All subjects underwent structural and fMRI testing using our navigational memory task, and a battery of neuropsychological testing. The activation patterns of the 15 subjects with concussion were compared with those of 15 age and sex-matched controls. Subtraction and regression analyses were performed using the matched controls along with scatter-plots using means and 95% quantiles of the 35 controls. While no differences were seen with neuropsychological testing or task performance, subjects with concussion had significantly diminished activation in the retrosplenial, thalamic, and parahippocampal areas bilaterally, along with the right dorsolateral prefrontal cortex and left precuneus. Interestingly, they had increased activation in the left hippocampus and right middle temporal gyrus. Regression analysis demonstrated negative correlations between activation and post-concussive symptoms in the left premotor cortex, superior and inferior parietal lobules, and parahippocampal gyrus. Subjects with concussion show both diminished and increased activation in specific cerebral regions, differentiating them from controls. This is one of the first studies to look at such a task using fMRI and its applicability in testing for concussion in children. These findings support navigational memory fMRI as a potential objective test for concussions. PMID:25270364

  14. The market for magnetic resonance spectroscopy

    SciTech Connect

    Carlson, L.

    1990-01-01

    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.

  15. Manipulation of Raman Resonances Using Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Desavage, Sara A.; Davis, Jon P.; Narducci, Frank A.

    2012-06-01

    We have theoretically and experimentally studied Raman resonances in multi-level atoms (specifically ^85Rb). Our emphasis has been on varying the relative orientation of the magnetic field with respect to the propagation direction of the Raman fields. We find that, in general, the spectrum consists of up to 11 peaks. By considering selection rules, we show that it is possible to orient the magnetic field so that either a 6 peak spectrum or 5 peak spectrum results, depending on whether the Raman fields contain a polarization component along the magnetic field direction or not. Furthermore, we find that the spectrum is not always symmetric with respect to the magnetically insensitive transition (clock transition). We explore the origins of the asymmetry and the overall shape of the spectra. We will discuss applications to magnetically sensitive atom interferometry.

  16. Diffusion magnetic resonance HE MAGNETIC resonance application that the rest of this thesis will be concerned with is that

    E-print Network

    Clayden, Jonathan D.

    4 Diffusion magnetic resonance imaging T HE MAGNETIC resonance application that the rest of this thesis will be concerned with is that of diffusion magnetic resonance imaging (dMRI). This chapter provides a brief description of diffusion and how it can be examined in the brain with dMRI. Mathematical

  17. Infantile Sandhoff's disease: multivoxel magnetic resonance spectrosecopy findings.

    PubMed

    Alkan, Alpay; Kutlu, Ramazan; Yakinci, Cengiz; Sigirci, Ahmet; Aslan, Mehmet; Sarac, Kaya

    2003-06-01

    Sandhoff's disease is a rare, genetic lysosomal storage disease leading to delayed myelination or demyelination. Although neuroimaging findings in this disease have been reported previously, magnetic resonance spectroscopy findings have not been reported. In this report, we present magnetic resonance imaging and magnetic resonance spectrscopy features of two cases with Sandhoff's disease. Magnetic resonance spectroscopy revealed findings indicating widespread demyelination in both cases and neuroaxonal loss and anaerobic metabolism in the second case. Magnetic resonance spectroscopy could provide useful information in the explanation of the clinical picture of cases with Sandhoff's disease. PMID:12886980

  18. A hyperpolarized equilibrium for magnetic resonance

    PubMed Central

    Hövener, Jan-Bernd; Schwaderlapp, Niels; Lickert, Thomas; Duckett, Simon B.; Mewis, Ryan E.; Highton, Louise A. R.; Kenny, Stephen M.; Green, Gary G. R.; Leibfritz, Dieter; Korvink, Jan G.; Hennig, Jürgen; von Elverfeldt, Dominik

    2013-01-01

    Nuclear magnetic resonance spectroscopy and imaging (MRI) play an indispensable role in science and healthcare but use only a tiny fraction of their potential. No more than ?10?p.p.m. of all 1H nuclei are effectively detected in a 3-Tesla clinical MRI system. Thus, a vast array of new applications lays dormant, awaiting improved sensitivity. Here we demonstrate the continuous polarization of small molecules in solution to a level that cannot be achieved in a viable magnet. The magnetization does not decay and is effectively reinitialized within seconds after being measured. This effect depends on the long-lived, entangled spin-order of parahydrogen and an exchange reaction in a low magnetic field of 10?3 Tesla. We demonstrate the potential of this method by fast MRI and envision the catalysis of new applications such as cancer screening or indeed low-field MRI for routine use and remote application. PMID:24336292

  19. Resonant dynamics of topological magnetic structures

    NASA Astrophysics Data System (ADS)

    Heinonen, Olle

    2014-03-01

    A variety of topological magnetic structures have recently been observed and discussed in atomic structures. Examples are spin ices in pyrochlore lattices, or skyrmion lattices in helical magnets, such as MnSi. Underlying these structures are competing interactions, which cannot all be simultaneously minimized. Patterned magnetic nanostructures can be engineered to have competing interactions that give rise to frustration, which can enable the formation of topological magnetic structures on the nanoscale and at room temperatures that can rather conveniently be observed. In addition to interesting ground states or metastable states, the resonant dynamics of topological structures can be very interesting and different from the dynamics of the non-topological states. This leads to the possibility of changing the resonant dynamics in magnetic system rather dramatically both in in frequency and space by small variations in a control parameter. In this introductory talk of the symposium, I will give examples of such states and the ensuing dynamics, and discuss possible future directions and applications.

  20. Magnetic resonance sounding applied to aquifer characterization.

    PubMed

    Legchenko, Anatoly; Baltassat, Jean-Michel; Bobachev, Alexey; Martin, Charlotte; Robain, Henri; Vouillamoz, Jean-Michel

    2004-01-01

    Magnetic resonance sounding (MRS) is distinguished from other geophysical tools used for ground water investigation by the fact that it measures a magnetic resonance signal generated directly from subsurface water molecules. An alternating current pulse energizes a wire loop on the ground surface and the MRS signal is generated; subsurface water is indicated, with a high degree of reliability, by nonzero amplitude readings. Measurements with varied pulse magnitudes then reveal the depth and thickness of water saturated layers. The hydraulic conductivity of aquifers can also be estimated using boreholes for calibration. MRS can be used for both predicting the yield of water supply wells and for interpolation between boreholes, thereby reducing the number of holes required for hydrogeological modeling. An example of the practical application of MRS combined with two-dimensional electrical imaging, in the Kerbernez and Kerien catchments area of France, demonstrates the efficiency of the technique. PMID:15161153

  1. Proton magnetic resonance spectroscopy in multiple sclerosis

    SciTech Connect

    Wolinsky, J.S.; Narayana, P.A.; Fenstermacher, M.J. (Univ. of Texas Health Science Center, Houston (USA))

    1990-11-01

    Regional in vivo proton magnetic resonance spectroscopy provides quantitative data on selected chemical constituents of brain. We imaged 16 volunteers with clinically definite multiple sclerosis on a 1.5 tesla magnetic resonance scanner to define plaque-containing volumes of interest, and obtained localized water-suppressed proton spectra using a stimulated echo sequence. Twenty-five of 40 plaque-containing regions provided spectra of adequate quality. Of these, 8 spectra from 6 subjects were consistent with the presence of cholesterol or fatty acids; the remainder were similar to those obtained from white matter of normal volunteers. This early experience with regional proton spectroscopy suggests that individual plaques are distinct. These differences likely reflect dynamic stages of the evolution of the demyelinative process not previously accessible to in vivo investigation.

  2. Study on the regulatory effect of electro-acupuncture on Hegu point (LI4) in cerebral response with functional magnetic resonance imaging

    Microsoft Academic Search

    Wei Wang; Ling Liu; Xin Zhi; Jin-bai Huang; Ding-xi Liu; Hua Wang; Xiang-quan Kong; Hai-bo Xu

    2007-01-01

    Objective  To study, through blood oxygen level dependent functional magnetic resonance imaging (BOLD fMRI), the cerebral activated areas\\u000a evoked by electro-acupuncturing (EA) the right Hegu point (LI4) or non-acupoint points on the face, and through comparing\\u000a their similarities and differences, to speculate on the specific cerebral areas activated by stimulating LI4, for exploring\\u000a the mechanism of its effect in potential clinical

  3. What is Involved and What is Necessary for Complex Linguistic and Nonlinguistic Auditory Processing: Evidence from Functional Magnetic Resonance Imaging and Lesion Data

    Microsoft Academic Search

    Frederic Dick; Ayse Pinar Saygin; Gaspare Galati; Sabrina Pitzalis; Simone Bentrovato; Simona D'amico; Stephen Wilson; Elizabeth Bates; Luigi Pizzamiglio

    2007-01-01

    We used functional magnetic resonance imaging (fMRI) in conjunction with a voxel-based approach to lesion symptom mapping to quantitatively evaluate the similarities and dif- ferences between brain areas involved in language and envi- ronmental sound comprehension. In general, we found that language and environmental sounds recruit highly overlapping cortical regions, with cross-domain differences being graded rather than absolute. Within language-based

  4. Ellipsoidal Coil for Magnetic Resonance Spectroscopy

    Microsoft Academic Search

    R. Hernandez; A. O. Rodriguez; P. Salgado; F. A. Barrios

    2003-01-01

    We developed an ellipse-shaped surface coil for magnetic resonance spectroscopy for a 1.5 T clinical MR Imager. This coil is to be used to obtain spectra from arms and legs. Standard volume and single-loop coils provide a poor signal because they can not be placed close to the region of interest and their shapes do not fit the anatomy of

  5. Sensorineural Hearing Loss after Magnetic Resonance Imaging

    PubMed Central

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

    2013-01-01

    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. PMID:23844303

  6. Alkali lasers for magnetic resonance imaging

    Microsoft Academic Search

    Boris V. Zhdanov; Randall J. Knize

    2010-01-01

    Spin-polarized nuclei of such gases as 3He and 129Xe are successfully used for magnetic resonance imaging of lungs and other organs of human body. To produce large numbers\\u000a of spin-polarized nuclei required for this medical application, a high power narrowband tunable laser source is required.\\u000a Diode pumped alkali lasers, developed during last several years can be an ideal source for

  7. Magnetic resonance imaging: Principles and applications

    SciTech Connect

    Kean, D.; Smith, M.

    1986-01-01

    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.

  8. Magnetic resonance urography: a pictorial overview

    Microsoft Academic Search

    R Garcia-Valtuille; A I GARCIA-VALTUILLE; F ABASCAL; L CEREZAL; M C ARGUELLO

    2006-01-01

    Magnetic resonance urography (MRU) can be performed on the basis of two different imaging strategies: static-fluid MRU, based on heavily T2 weighted turbo spin echo (TSE) sequences, and gadolinium-enhanced excretory MRU. Both MR urographic techniques in combination with standard MRI permit a comprehensive examination of the entire urinary tract. This pictorial review illustrates the MRU features of the a wide

  9. Structural magnetic resonance imaging in epilepsy

    Microsoft Academic Search

    Karel Deblaere; Eric Achten

    2008-01-01

    Because of its sensitivity and high tissue contrast, magnetic resonance imaging (MRI) is the technique of choice for structural\\u000a imaging in epilepsy. In this review the effect of using optimised scanning protocols and the use of high field MR systems\\u000a on detection sensitivity is discussed. Also, the clinical relevance of adequate imaging in patients with focal epilepsy is\\u000a highlighted. The

  10. Resonantly detecting axion-mediated forces with nuclear magnetic resonance.

    PubMed

    Arvanitaki, Asimina; Geraci, Andrew A

    2014-10-17

    We describe a method based on precision magnetometry that can extend the search for axion-mediated spin-dependent forces by several orders of magnitude. By combining techniques used in nuclear magnetic resonance and short-distance tests of gravity, our approach can substantially improve upon current experimental limits set by astrophysics, and probe deep into the theoretically interesting regime for the Peccei-Quinn (PQ) axion. Our method is sensitive to PQ axion decay constants between 10(9) and 10(12) GeV or axion masses between 10(-6) and 10(-3) eV, independent of the cosmic axion abundance. PMID:25361250

  11. Fluctuating magnetic field induced resonant activation.

    PubMed

    Mondal, Shrabani; Das, Sudip; Baura, Alendu; Bag, Bidhan Chandra

    2014-12-14

    In this paper, we have studied the properties of a Brownian particle at stationary state in the presence of a fluctuating magnetic field. Time dependence of the field makes the system thermodynamically open. As a signature of that the steady state distribution function becomes function of damping strength, intensity of fluctuations and constant parts of the applied magnetic field. It also depends on the correlation time of the fluctuating magnetic field. Our another observation is that the random magnetic field can induce the resonant activation phenomenon. Here correlation time is increased under the fixed variance of the fluctuating field. But if the correlation time (?) increases under the fixed field strength then the mean first passage time rapidly grows at low ? and it almost converges at other limit. This is sharp contrast to the usual colored noise driven open system case where the mean first passage time diverges exponentially. We have also observed that a giant enhancement of barrier crossing rate occurs particularly at large strength of constant parts of the applied magnetic field even for very weak fluctuating magnetic field. Finally, break down of the Arrhenius result and disappearance of the Kramers' turn over phenomenon may occur in the presence of a fluctuating magnetic field. PMID:25494726

  12. [fMRI study of deliberate deception].

    PubMed

    Kireev, M V; Korotkov, A D; Medvedev, C V

    2012-01-01

    The aim of the present research was to study the deliberate deception. Event related functional magnetic resonance (fMRI) imaging technique was used to assess the changes in functional brain activity by virtue of recording blood oxygen level dependant signal (BOLD-signal). 12 right-handed healthy volunteers aged 19-44 participated in the study. BOLD images were acquired in three different experimental trials. There were deliberate deception, manipulative honest and control truthful trials (catch trials). The main finding of the present study is that the deliberate deception and manipulative honest actions in comparison with instructed truthful responding was characterized by BOLD signal increase within the anterior cingulated cortex (ACC), frontal and parietal areas as well. Comparison of present fMRI data with results demonstrated in our previous research implemented with event related potentials technique points to the involvement of the brain mechanism of error detection to brain processing of deliberate deception. PMID:22567835

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

    PubMed Central

    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

    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. PMID:22314879

  14. [Lie detection and mind reading: is there a use for fMRI?: A critical survey and reflection].

    PubMed

    Ruchsow, M; Hermle, L; Kober, M

    2010-09-01

    Great efforts have been made in recent years to use functional magnetic resonance imaging (fMRI) in the context of lie detection. In the present paper the pros and cons of such an approach are analyzed and critically discussed.Both epistemological and methodical considerations have shown that all attempts to derive mental states from fMRI findings ("reverse inference") are not valid. Consequently, fMRI scans cannot reveal a person's thoughts and whether (s)he is lying or telling the truth. PMID:20162411

  15. Comprehensive mathematical simulation of functional magnetic resonance imaging time series including motion-related image distortion and spin saturation effect.

    PubMed

    Kim, Boklye; Yeo, Desmond T B; Bhagalia, Roshni

    2008-02-01

    There has been vast interest in determining the feasibility of functional magnetic resonance imaging (fMRI) as an accurate method of imaging brain function for patient evaluations. The assessment of fMRI as an accurate tool for activation localization largely depends on the software used to process the time series data. The performance evaluation of different analysis tools is not reliable unless truths in motion and activation are known. Lack of valid truths has been the limiting factor for comparisons of different algorithms. Until now, currently available phantom data do not include comprehensive accounts of head motion. While most fMRI studies assume no interslice motion during the time series acquisition in fMRI data acquired using a multislice and single-shot echo-planar imaging sequence, each slice is subject to a different set of motion parameters. In this study, in addition to known three-dimensional motion parameters applied to each slice, included in the time series computation are geometric distortion from field inhomogeneity and spin saturation effect as a result of out-of-plane head motion. We investigated the effect of these head motion-related artifacts and present a validation of the mapping slice-to-volume (MSV) algorithm for motion correction and activation detection against the known truths. MSV was evaluated, and showed better performance in comparison with other widely used fMRI data processing software, which corrects for head motion with a volume-to-volume realignment method. Furthermore, improvement in signal detection was observed with the implementation of the geometric distortion correction and spin saturation effect compensation features in MSV. PMID:17662548

  16. Compact low field magnetic resonance imaging magnet: Design and optimization

    NASA Astrophysics Data System (ADS)

    Sciandrone, M.; Placidi, G.; Testa, L.; Sotgiu, A.

    2000-03-01

    Magnetic resonance imaging (MRI) is performed with a very large instrument that allows the patient to be inserted into a region of uniform magnetic field. The field is generated either by an electromagnet (resistive or superconductive) or by a permanent magnet. Electromagnets are designed as air cored solenoids of cylindrical symmetry, with an inner bore of 80-100 cm in diameter. In clinical analysis of peripheral regions of the body (legs, arms, foot, knee, etc.) it would be better to adopt much less expensive magnets leaving the most expensive instruments to applications that require the insertion of the patient in the magnet (head, thorax, abdomen, etc.). These "dedicated" apparati could be smaller and based on resistive magnets that are manufactured and operated at very low cost, particularly if they utilize an iron yoke to reduce power requirements. In order to obtain good field uniformity without the use of a set of shimming coils, we propose both particular construction of a dedicated magnet, using four independently controlled pairs of coils, and an optimization-based strategy for computing, a posteriori, the optimal current values. The optimization phase could be viewed as a low-cost shimming procedure for obtaining the desired magnetic field configuration. Some experimental measurements, confirming the effectiveness of the proposed approach (construction and optimization), have also been reported. In particular, it has been shown that the adoption of the proposed optimization based strategy has allowed the achievement of good uniformity of the magnetic field in about one fourth of the magnet length and about one half of its bore. On the basis of the good experimental results, the dedicated magnet can be used for MRI of peripheral regions of the body and for animal experimentation at very low cost.

  17. Multifunctional magnetic nanoparticles for magnetic resonance imaging and cancer therapy

    Microsoft Academic Search

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

    2011-01-01

    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

  18. Portal biliopathy, magnetic resonance imaging and magnetic resonance cholangiopancreatography findings: a case series.

    PubMed

    Baskan, Ozdil; Erol, Cengiz; Sahingoz, Yusuf

    2014-09-12

    Portal biliopathy (PB) is a rare disorder, characterized by biliary ductal and gallbladder wall abnormalities seen in patients with portal hypertension. It most commonly occurs due to idiopathic extrahepatic portal vein obstruction (EHPVO). The abnormalities consist mainly of bile duct compression, stenoses, fibrotic strictures and dilation of both extrahepatic and intrahepatic bile ducts, as well as gallbladder varices. PB may mimic cholangiocarcinoma, sclerosing cholangitis, or choledocholithiasis. Misdiagnosis can be avoided using appropriate imaging modalities to prevent complications. We present the magnetic resonance imaging (MRI) and magnetic resonance cholangiography (MRCP) features of three patients with PB. PMID:25216728

  19. Adaptation of a haptic robot in a 3T fMRI.

    PubMed

    Snider, Joseph; Plank, Markus; May, Larry; Liu, Thomas T; Poizner, Howard

    2011-01-01

    Functional magnetic resonance imaging (fMRI) provides excellent functional brain imaging via the BOLD signal with advantages including non-ionizing radiation, millimeter spatial accuracy of anatomical and functional data, and nearly real-time analyses. Haptic robots provide precise measurement and control of position and force of a cursor in a reasonably confined space. Here we combine these two technologies to allow precision experiments involving motor control with haptic/tactile environment interaction such as reaching or grasping. The basic idea is to attach an 8 foot end effecter supported in the center to the robot allowing the subject to use the robot, but shielding it and keeping it out of the most extreme part of the magnetic field from the fMRI machine (Figure 1). The Phantom Premium 3.0, 6DoF, high-force robot (SensAble Technologies, Inc.) is an excellent choice for providing force-feedback in virtual reality experiments, but it is inherently non-MR safe, introduces significant noise to the sensitive fMRI equipment, and its electric motors may be affected by the fMRI's strongly varying magnetic field. We have constructed a table and shielding system that allows the robot to be safely introduced into the fMRI environment and limits both the degradation of the fMRI signal by the electrically noisy motors and the degradation of the electric motor performance by the strongly varying magnetic field of the fMRI. With the shield, the signal to noise ratio (SNR: mean signal/noise standard deviation) of the fMRI goes from a baseline of ~380 to ~330, and ~250 without the shielding. The remaining noise appears to be uncorrelated and does not add artifacts to the fMRI of a test sphere (Figure 2). The long, stiff handle allows placement of the robot out of range of the most strongly varying parts of the magnetic field so there is no significant effect of the fMRI on the robot. The effect of the handle on the robot's kinematics is minimal since it is lightweight (~2.6 lbs) but extremely stiff 3/4" graphite and well balanced on the 3DoF joint in the middle. The end result is an fMRI compatible, haptic system with about 1 cubic foot of working space, and, when combined with virtual reality, it allows for a new set of experiments to be performed in the fMRI environment including naturalistic reaching, passive displacement of the limb and haptic perception, adaptation learning in varying force fields, or texture identification. PMID:21989084

  20. Cerebral reorganization as a function of linguistic recovery in children: An fMRI study

    Microsoft Academic Search

    Odelia Elkana; Ram Frost; Uri Kramer; Dafna Ben-Bashat; Talma Hendler; David Schmidt; Avraham Schweiger

    2011-01-01

    Characterizing and mapping the relationship between neuronal reorganization and functional recovery are essential to the understanding of cerebral plasticity and the dynamic processes which occur following brain damage. The neuronal mechanisms underlying linguistic recovery following left hemisphere (LH) lesions are still unknown. Using functional magnetic resonance imaging (fMRI), we investigated whether the extent of brain lateralization of linguistic functioning in

  1. Simultaneous ERP and fMRI of the auditory cortex in a passive oddball paradigm

    E-print Network

    Gabrieli, John

    Simultaneous ERP and fMRI of the auditory cortex in a passive oddball paradigm Einat Liebenthal of repetitive standard sounds elicit the automatic mismatch negativity (MMN) event-related potential (ERP, and temporal sequence of activation remain unclear. In this study, ERP and functional magnetic resonance

  2. Perception of Biological Motion in Schizophrenia and Healthy Individuals: A Behavioral and fMRI Study

    Microsoft Academic Search

    Jejoong Kim; Sohee Park; Randolph Blake

    2011-01-01

    BackgroundAnomalous visual perception is a common feature of schizophrenia plausibly associated with impaired social cognition that, in turn, could affect social behavior. Past research suggests impairment in biological motion perception in schizophrenia. Behavioral and functional magnetic resonance imaging (fMRI) experiments were conducted to verify the existence of this impairment, to clarify its perceptual basis, and to identify accompanying neural concomitants

  3. fMRI activation maps based on the NN-ARx model

    Microsoft Academic Search

    J. Riera; J. Bosch; O. Yamashita; R. Kawashima; N. Sadato; T. Okada; T. Ozaki

    2004-01-01

    The most significant progresses in the understanding of human brain functions have been possible due to the use of functional magnetic resonance imaging (fMRI), which when used in combination with other standard neuroimaging techniques (i.e., EEG) provides researchers with a potential tool to elucidate many biophysical principles, established previously by animal comparative studies. However, to date, most of the methods

  4. Detection of deception with fMRI: Are we there yet?

    Microsoft Academic Search

    Daniel D. Langleben

    2008-01-01

    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

  5. Event-related fMRI of tasks involving brief motion

    Microsoft Academic Search

    Rasmus M. Birn; Peter A. Bandettini; Robert W. Cox; Reza Shaker

    1999-01-01

    r r Abstract: The assessment of brain function by blood oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI) for tasks involving motion near the field of view is compromised by artifacts arising from the motion. The aim of this study is to demonstrate that these artifacts can be reduced by acquiring the average response from a brief stimulus (a

  6. Functional abnormalities in symptomatic concussed athletes: an fMRI study

    Microsoft Academic Search

    J.-K Chen; K. M Johnston; S Frey; M Petrides; K Worsley; A Ptito

    2004-01-01

    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)

  7. An fMRI task battery for assessing hemispheric language dominance in children

    Microsoft Academic Search

    Marko Wilke; Karen Lidzba; Martin Staudt; Karin Buchenau; Wolfgang Grodd; Ingeborg Krägeloh-Mann

    2006-01-01

    Hemispheric dominance for language is an important issue in functional neuroimaging, particularly driven by efforts to overcome the need for the invasive Wada test, which is all the more pressing in children. Here, we aimed at developing new paradigms for functional magnetic resonance imaging (fMRI) for assessment of language dominance that can be used in younger children and allow for

  8. Attention to emotion modulates fMRI activity in human right superior temporal sulcus

    Microsoft Academic Search

    Jin Narumoto; Tomohisa Okada; Norihiro Sadato; Kenji Fukui; Yoshiharu Yonekura

    2001-01-01

    A parallel neural network has been proposed for processing various types of information conveyed by faces including emotion. Using functional magnetic resonance imaging (fMRI), we tested the effect of the explicit attention to the emotional expression of the faces on the neuronal activity of the face-responsive regions. Delayed match to sample procedure was adopted. Subjects were required to match the

  9. A Quantitative Comparison of Simultaneous BOLD fMRI and NIRS Recordings during Functional Brain Activation

    Microsoft Academic Search

    Gary Strangman; Joseph P. Culver; John H. Thompson; David A. Boas

    2002-01-01

    Near-infrared spectroscopy (NIRS) has been used to noninvasively monitor adult human brain func- tion in a wide variety of tasks. While rough spatial correspondences with maps generated from func- tional magnetic resonance imaging (fMRI) have been found in such experiments, the amplitude cor- respondences between the two recording modalities have not been fully characterized. To do so, we si- multaneously

  10. Quantifying Head Motion Associated with Motor Tasks Used in fMRI

    Microsoft Academic Search

    E. Seto; G. Sela; W. E. McIlroy; S. E. Black; W. R. Staines; M. J. Bronskill; A. R. McIntosh; S. J. Graham

    2001-01-01

    In functional magnetic resonance imaging (fMRI) studies, long experiment times and small intensity changes associated with brain activation frequently lead to image artifacts due to head motion. Methods to minimize and correct for head motion by restraint, fast imaging, and retrospective image registration are typically combined but do not completely solve the problem, particularly for specific patient populations. As an

  11. Gender Differences in the Cognitive Control of Emotion: An fMRI Study

    ERIC Educational Resources Information Center

    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

    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 stimulation…

  12. Differences in Processing of Taxonomic and Sequential Relations in Semantic Memory: An fMRI Investigation

    ERIC Educational Resources Information Center

    Kuchinke, Lars; van der Meer, Elke; Krueger, Frank

    2009-01-01

    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:…

  13. What Has fMRI Told Us about the Development of Cognitive Control through Adolescence?

    ERIC Educational Resources Information Center

    Luna, Beatriz; Padmanabhan, Aarthi; O'Hearn, Kirsten

    2010-01-01

    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…

  14. Are Errors Differentiable from Deceptive Responses when Feigning Memory Impairment? An fMRI Study

    ERIC Educational Resources Information Center

    Lee, Tatia M. C.; Au, Ricky K. C.; Liu, Ho-Ling; Ting, K. H.; Huang, Chih-Mao; Chan, Chetwyn C. H.

    2009-01-01

    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…

  15. Passive tactile recognition of geometrical shape in humans: An fMRI study

    Microsoft Academic Search

    Nicoletta Savini; Claudio Babiloni; Marcella Brunetti; Massimo Caulo; Cosimo Del Gratta; Mauro Gianni Perrucci; Paolo Maria Rossini; Gian Luca Romani; Antonio Ferretti

    2010-01-01

    Tactile shape discrimination involves frontal other than somatosensory cortex (Palva et al., 2005 [48]), but it is unclear if this frontal activity is related to exploratory concomitants. In this study, we investigated topographical details of prefrontal, premotor, and parietal areas during passive tactile recognition of 2D geometrical shapes in conditions avoiding exploratory movements. Functional magnetic resonance imaging (fMRI) was performed

  16. Language Switching and Language Representation in Spanish–English Bilinguals: An fMRI Study

    Microsoft Academic Search

    Arturo E. Hernandez; Mirella Dapretto; John Mazziotta; Susan Bookheimer

    2001-01-01

    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 also asked to name (only in English) a separate set of

  17. Independent component analysis of fMRI group studies by self-organizing clustering

    Microsoft Academic Search

    Fabrizio Easposito; Tommaso Scarabino; Aapo Hyvarinen; Johan Himberg; Elia Formisano; Silvia Comani; Gioacchino Tedeschi; Rainer Goebel; Erich Seifritz; Francesco Di Salle

    2005-01-01

    Independent component analysis (ICA) is a valuable technique for the multivariate data-driven analysis of functional magnetic resonance imaging (fMRI) data sets. Applications of ICA have been developed mainly for single subject studies, although different solutions for group studies have been proposed. These approaches combine data sets from multiple subjects into a single aggregate data set before ICA estimation and, thus,

  18. Utilizing temporal information in fMRI decoding: Classifier using kernel regression methods

    Microsoft Academic Search

    Carlton Chu; Janaina Mourão-Miranda; Yu-Chin Chiu; Nikolaus Kriegeskorte; Geoffrey Tan; John Ashburner

    2011-01-01

    This paper describes a general kernel regression approach to predict experimental conditions from activity patterns acquired with functional magnetic resonance image (fMRI). The standard approach is to use classifiers that predict conditions from activity patterns. Our approach involves training different regression machines for each experimental condition, so that a predicted temporal profile is computed for each condition. A decision function

  19. Integration of EEG source imaging and fMRI during continuous viewing of natural movies

    Microsoft Academic Search

    Kevin Whittingstall; Andreas Bartels; Vanessa Singh; Soyoung Kwon; Nikos K. Logothetis

    2010-01-01

    Electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) are noninvasive neuroimaging tools which can be used to measure brain activity with excellent temporal and spatial resolution, respectively. By combining the neural and hemodynamic recordings from these modalities, we can gain better insight into how and where the brain processes complex stimuli, which may be especially useful in patients with different

  20. Predicting events of varying probability: uncertainty investigated by fMRI

    Microsoft Academic Search

    Kirsten G Volz; Ricarda I Schubotz; D. Yves von Cramon

    2003-01-01

    Many everyday life predictions rely on the experience and memory of event frequencies, i.e., natural samplings. We used functional magnetic resonance imaging (fMRI) to investigate the neural substrates of prediction under varying uncertainty based on a natural sampling approach. The study focused particularly on a comparison with other types of externally attributed uncertainty, such as guessing, and on the frontomedian

  1. Left superior parietal cortex involvement in writing: integrating fMRI with lesion evidence

    Microsoft Academic Search

    V Menon; J. E Desmond

    2001-01-01

    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

  2. SPHARM-Based Spatial fMRI Characterization With Intersubject Anatomical Variability Reduction

    Microsoft Academic Search

    Ashish Uthama; Rafeef Abugharbieh; Samantha J. Palmer; Anthony Traboulsee; Martin J. McKeown

    2008-01-01

    It has been recently shown that spatial patterns of activation within regions of interest (ROIs) in functional magnetic resonance imaging (fMRI) data can be used as sensitive markers of brain activation differences. In this paper, we propose novel invariant features for characterizing such spatial activation patterns based on spherical harmonic (SPHARM) data representations. The proposed three dimensional (3-D) spatial features

  3. Parsing a sequence of brain activations at psychological times using fMRI

    Microsoft Academic Search

    M. Sigman; A. Jobert; D. LeBihan; S. Dehaene

    2007-01-01

    Identifying the sequence of computations which constitute a cognitive task is a fundamental problem in neuroscience. Here we show, using functional magnetic resonance imaging (fMRI), that we can parse, at the time scale of about 100 ms, the different stages of brain activations which compose a complex sequential task. To identify timing information from the slow blood oxygen level-dependent (BOLD)

  4. Improvements in Magnetic Resonance Imaging Excitation Pulse Design

    E-print Network

    Improvements in Magnetic Resonance Imaging Excitation Pulse Design by Adam Charles Zelinski;#12;Improvements in Magnetic Resonance Imaging Excitation Pulse Design by Adam Charles Zelinski Submitted inhomogeneity limitations. When magnetic spins are tilted by only a small amount, pulse transmission may

  5. Magnetic Resonance Driven Electrical Impedance Tomography: A Simulation Study

    Microsoft Academic Search

    Michiro Negishi; Tangji Tong; R. Todd Constable

    2011-01-01

    Magnetic resonance electrical impedance tomog- raphy (MREIT) is a method for reconstructing a three-dimen- sional image of the conductivity distribution in a target volume using magnetic resonance (MR). In MREIT, currents are applied to the volume through surface electrodes and their effects on the MR induced magnetic fields are analyzed to produce the conductance image. However, current injection through surface

  6. Molecular structure and motion in zero field magnetic resonance

    SciTech Connect

    Jarvie, T.P.

    1989-10-01

    Zero field magnetic resonance is well suited for the determination of molecular structure and the study of motion in disordered materials. Experiments performed in zero applied magnetic field avoid the anisotropic broadening in high field nuclear magnetic resonance (NMR) experiments. As a result, molecular structure and subtle effects of motion are more readily observed.

  7. Pulsed Nuclear Magnetic Resonance: Spin Echoes MIT Department of Physics

    E-print Network

    Seager, Sara

    Pulsed Nuclear Magnetic Resonance: Spin Echoes MIT Department of Physics (Dated: February 5, 2014) In this experiment, the phenomenon of Nuclear Magnetic Resonance (NMR) is used to determine the magnetic moments-factor in atomic spectroscopy and is given by g = (µ/µN )/I, (2) and µN is the nuclear magneton, e /2mp

  8. Imagined transformations of bodies: an fMRI investigation

    Microsoft Academic Search

    Jeff Zacks; Bart Rypma; J. D. E. Gabrieli; Barbara Tversky; Gary H. Glover

    1999-01-01

    A number of spatial reasoning problems can be solved by performing an imagined transformation of one’s egocentric perspective. A series of experiments were carried out to characterize this process behaviorally and in terms of its brain basis, using functional magnetic resonance imaging (fMRI). In a task contrast designed to isolate egocentric perspective transformations, participants were slower to make left-right judgments

  9. The neural substrates of mindfulness: An fMRI investigation

    Microsoft Academic Search

    Victoria L. Ives-Deliperi; Mark Solms; Ernesta M. Meintjes

    2011-01-01

    “Mindfulness” is a capacity for heightened present-moment awareness that we all possess to a greater or lesser extent. Enhancing this capacity through training has been shown to alleviate stress and promote physical and mental well-being. As a consequence, interest in mindfulness is growing and so is the need to better understand it. This study employed functional magnetic resonance imaging (fMRI)

  10. Nanodiamond graphitization: a magnetic resonance study

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

    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.

  11. Cardiovascular magnetic resonance imaging in small animals.

    PubMed

    Botnar, René M; Makowski, Marcus R

    2012-01-01

    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

  12. Review: Magnetic resonance imaging techniques in ophthalmology

    PubMed Central

    Fagan, Andrew J.

    2012-01-01

    Imaging the eye with magnetic resonance imaging (MRI) has proved difficult due to the eye’s propensity to move involuntarily over typical imaging timescales, obscuring the fine structure in the eye due to the resulting motion artifacts. However, advances in MRI technology help to mitigate such drawbacks, enabling the acquisition of high spatiotemporal resolution images with a variety of contrast mechanisms. This review aims to classify the MRI techniques used to date in clinical and preclinical ophthalmologic studies, describing the qualitative and quantitative information that may be extracted and how this may inform on ocular pathophysiology. PMID:23112569

  13. Magnetic resonance imaging of cartilage repair procedures.

    PubMed

    Forney, Michael C; Gupta, Amit; Minas, Tom; Winalski, Carl S

    2014-11-01

    Cartilage injuries in the knee are common and can be a persistent source of pain or dysfunction. Many new surgical strategies have been developed to treat these lesions. It is important for the radiologist to have an understanding of these procedures and their appearance on magnetic resonance (MR) imaging. This article provides the radiologist with an overview of the surgical strategies for repairing cartilage lesions in the knee followed by a discussion of their postoperative appearance on MR imaging in normal and abnormal cases. Guidelines for adequate reporting of the MR imaging findings after cartilage repair in the knee are also included. PMID:25442028

  14. Magnetic resonance imaging in gynecological oncology.

    PubMed

    Harry, Vanessa N; Deans, Heather; Ramage, Emma; Parkin, David E; Gilbert, Fiona J

    2009-02-01

    Magnetic resonance imaging (MRI) has become an indispensable tool in the assessment of malignant disease. With increasingly sophisticated systems and technical advancements, MRI has continued to expand its role in providing crucial information regarding cancer diagnosis and management. In gynecological malignancies, this modality has assumed greater responsibility, particularly in the evaluation of cervical and endometrial cancers. In addition to conventional imaging, innovative techniques such as dynamic contrast-enhanced MRI and diffusion-weighted MRI show promise in offering early assessment of tumor response. This paper reviews the current role of MRI in gynecological cancers and highlights the potential of novel techniques in improving patient care. PMID:19395992

  15. Cardiomyopathies: focus on cardiovascular magnetic resonance

    PubMed Central

    Quarta, G; Sado, D M; Moon, J C

    2011-01-01

    Cardiomyopathies (CMPs) are a group of often inherited diseases characterised by abnormalities and associated dysfunction of heart muscle. In the past decade, cardiovascular magnetic resonance (CMR) has emerged as a powerful tool in their assessment, providing data that are complementary to other aspects of clinical evaluation. Key advantages of CMR are three-dimensional visualisation of the heart and its relationship to thoracic structures; gold-standard quantification of cardiac volumes and function, which can safely be repeated over time (no ionising radiation is involved); and tissue characterisation to detect focal scar and fatty infiltration. This paper reviews the role of CMR in the clinical assessment of patients with CMPs. PMID:22723536

  16. Magnetic resonance of the musculoskeletal system

    SciTech Connect

    Berquist, T.H.; Ehman, R.L.; Richardson, M.L.

    1986-01-01

    Magnetic Resonance of the Musculoskeletal System features coverage of the use of MRI in evaluation of specific diseases: bone and soft tissue tumors; infections; musculoskeletal trauma; spinal disorders; and miscellaneous conditions. The authors comparisons of MRI with computed tomography, ultrasound, isotopes, and other techniques will assist the physician in determining which clinical problems are best evaluated by MRI. Where MRI is the optimal technique, the text outlines the examination procedure, indicates which sequences provide the most information, and describes the pathologic findings that can be observed in MRI scans. An outstanding selection of more than 250 detail-revealing illustrations depicts representatives MRI findings.

  17. Magnetic resonance imaging of perianal fistulas.

    PubMed

    Vanbeckevoort, Dirk; Bielen, Didier; Vanslembrouck, Ragna; Van Assche, Gert

    2014-02-01

    Perianal fistulization is the result of a chronic inflammation of the perianal tissues. A wide spectrum of clinical manifestations, ranging from simple to complex fistulas, can be seen, the latter especially in patients with Crohn disease. Failure to detect secondary tracks and hidden abscesses may lead to therapeutic failure, such as insufficient response to medical treatment and relapse after surgery. Currently, magnetic resonance (MR) imaging is the preferred technique for evaluating perianal fistulas and associated complications. Initially used most often in the preoperative setting, MR imaging now also plays an important role in evaluating the response to medical therapy. PMID:24238135

  18. Developments in boron magnetic resonance imaging (MRI)

    SciTech Connect

    Schweizer, M.

    1995-11-01

    This report summarizes progress during the past year on maturing Boron-11 magnetic resonance imaging (MRI) methodology for noninvasive determination of BNCT agents (BSH) spatially in time. Three major areas are excerpted: (1) Boron-11 MRI of BSH distributions in a canine intracranial tumor model and the first human glioblastoma patient, (2) whole body Boron-11 MRI of BSH pharmacokinetics in a rat flank tumor model, and (3) penetration of gadolinium salts through the BBB as a function of tumor growth in the canine brain.

  19. Magnetic resonance imaging features of allografts

    Microsoft Academic Search

    S. V. Kattapuram; M. S. Rosol; D. I. Rosenthal; W. E. Palmer; H. J. Mankin

    1999-01-01

    Objective. To investigate the magnetic resonance imaging (MRI) features of allografts at various time intervals after surgery in patients\\u000a with osteoarticular allografts.\\u000a \\u000a \\u000a Design and patients. Sixteen patients who were treated with osteoarticular allografts and who were followed over time with MRI studies as part\\u000a of their long-term follow-up were retrospectively selected for this study. T1-weighted images were obtained both before

  20. A Submicrosecond Resonator and Receiver System for Pulsed Magnetic Resonance with Large Samples

    Microsoft Academic Search

    M. Alecci; J. A. Brivati; G. Placidi; L. Testa; D. J. Lurie; A. Sotgiu

    1998-01-01

    We describe a submicrosecond resonator and receiver system for use in pulsed magnetic resonance at 220 MHz. This new resonator and receiver system design enables a reduction of the dead time, and in principle its complete elimination. We show experimentally that the resonator and receiver system permits the detection of free induction decay signals 300 ns from the end of

  1. Clinical applications of cardiovascular magnetic resonance imaging

    PubMed Central

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

    2006-01-01

    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. PMID:17030942

  2. Novel Magnetic Resonance Imaging Techniques in Brain Tumors.

    PubMed

    Nechifor, Ruben E; Harris, Robert J; Ellingson, Benjamin M

    2015-06-01

    Magnetic resonance imaging is a powerful, noninvasive imaging technique with exquisite sensitivity to soft tissue composition. Magnetic resonance imaging is primary tool for brain tumor diagnosis, evaluation of drug response assessment, and clinical monitoring of the patient during the course of their disease. The flexibility of magnetic resonance imaging pulse sequence design allows for a variety of image contrasts to be acquired, including information about magnetic resonance-specific tissue characteristics, molecular dynamics, microstructural organization, vascular composition, and biochemical status. The current review highlights recent advancements and novel approaches in MR characterization of brain tumors. PMID:26049817

  3. LASER-POLARIZED 129Xe MAGNETIC RESONANCE SPECTROSCOPY AND IMAGING;

    E-print Network

    Rosen, Matthew S

    LASER-POLARIZED 129Xe MAGNETIC RESONANCE SPECTROSCOPY AND IMAGING; THE DEVELOPMENT OF A METHOD ............................................................................38 3.2 Laser System and Optics

  4. Spatial Bayesian Variable Selection Models on Functional Magnetic Resonance Imaging Time-Series Data

    PubMed Central

    Lee, Kuo-Jung; Jones, Galin L.; Caffo, Brian S.; Bassett, Susan Spear

    2014-01-01

    A common objective of fMRI (functional magnetic resonance imaging) studies is to determine subject-specific areas of increased blood oxygenation level dependent (BOLD) signal contrast in response to a stimulus or task, and hence to infer regional neuronal activity. We posit and investigate a Bayesian approach that incorporates spatial and temporal dependence and allows for the task-related change in the BOLD signal to change dynamically over the scanning session. In this way, our model accounts for potential learning effects in addition to other mechanisms of temporal drift in task-related signals. We study the properties of the model through its performance on simulated and real data sets. PMID:25530824

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

    PubMed

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

    2013-06-01

    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

  6. Breaking down the barriers: fMRI applications in pain, analgesia and analgesics

    PubMed Central

    Borsook, David; Becerra, Lino R

    2006-01-01

    This review summarizes functional magnetic resonance imaging (fMRI) findings that have informed our current understanding of pain, analgesia and related phenomena, and discusses the potential role of fMRI in improved therapeutic approaches to pain. It is divided into 3 main sections: (1) fMRI studies of acute and chronic pain. Physiological studies of pain have found numerous regions of the brain to be involved in the interpretation of the 'pain experience'; studies in chronic pain conditions have identified a significant CNS component; and fMRI studies of surrogate models of chronic pain are also being used to further this understanding. (2) fMRI studies of endogenous pain processing including placebo, empathy, attention or cognitive modulation of pain. (3) The use of fMRI to evaluate the effects of analgesics on brain function in acute and chronic pain. fMRI has already provided novel insights into the neurobiology of pain. These insights should significantly advance therapeutic approaches to chronic pain. PMID:16982005

  7. The impact of denoising on independent component analysis of functional magnetic resonance imaging data.

    PubMed

    Pignat, Jean Michel; Koval, Oleksiy; Van De Ville, Dimitri; Voloshynovskiy, Sviatoslav; Michel, Christoph; Pun, Thierry

    2013-02-15

    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

  8. Real-time functional magnetic resonance imaging neurofeedback for treatment of Parkinson's disease.

    PubMed

    Subramanian, Leena; Hindle, John V; Johnston, Stephen; Roberts, Mark V; Husain, Masud; Goebel, Rainer; Linden, David

    2011-11-01

    Self-regulation of brain activity in humans based on real-time feedback of functional magnetic resonance imaging (fMRI) signal is emerging as a potentially powerful, new technique. Here, we assessed whether patients with Parkinson's disease (PD) are able to alter local brain activity to improve motor function. Five patients learned to increase activity in the supplementary motor complex over two fMRI sessions using motor imagery. They attained as much activation in this target brain region as during a localizer procedure with overt movements. Concomitantly, they showed an improvement in motor speed (finger tapping) and clinical ratings of motor symptoms (37% improvement of the motor scale of the Unified Parkinson's Disease Rating Scale). Activation during neurofeedback was also observed in other cortical motor areas and the basal ganglia, including the subthalamic nucleus and globus pallidus, which are connected to the supplementary motor area (SMA) and crucial nodes in the pathophysiology of PD. A PD control group of five patients, matched for clinical severity and medication, underwent the same procedure but did not receive feedback about their SMA activity. This group attained no control of SMA activation and showed no motor improvement. These findings demonstrate that self-modulation of cortico-subcortical motor circuits can be achieved by PD patients through neurofeedback and may result in clinical benefits that are not attainable by motor imagery alone. PMID:22072682

  9. Improving the spatial resolution of magnetic resonance inverse imaging via the blipped-CAIPI acquisition scheme.

    PubMed

    Chang, Wei-Tang; Setsompop, Kawin; Ahveninen, Jyrki; Belliveau, John W; Witzel, Thomas; Lin, Fa-Hsuan

    2014-05-01

    Using simultaneous acquisition from multiple channels of a radio-frequency (RF) coil array, magnetic resonance inverse imaging (InI) achieves functional MRI acquisitions at a rate of 100ms per whole-brain volume. InI accelerates the scan by leaving out partition encoding steps and reconstructs images by solving under-determined inverse problems using RF coil sensitivity information. Hence, the correlated spatial information available in the coil array causes spatial blurring in the InI reconstruction. Here, we propose a method that employs gradient blips in the partition encoding direction during the acquisition to provide extra spatial encoding in order to better differentiate signals from different partitions. According to our simulations, this blipped-InI (bInI) method can increase the average spatial resolution by 15.1% (1.3mm) across the whole brain and from 32.6% (4.2mm) in subcortical regions, as compared to the InI method. In a visual fMRI experiment, we demonstrate that, compared to InI, the spatial distribution of bInI BOLD response is more consistent with that of a conventional echo-planar imaging (EPI) at the level of individual subjects. With the improved spatial resolution, especially in subcortical regions, bInI can be a useful fMRI tool for obtaining high spatiotemporal information for clinical and cognitive neuroscience studies. PMID:24374076

  10. Magnetic resonance imaging predictors of treatment response in late-life depression.

    PubMed

    Aizenstein, Howard J; Khalaf, Alexander; Walker, Sarah E; Andreescu, Carmen

    2014-03-01

    In older adults, depression not only results in more years lived with disability than any other disease but it also carries additional risks of suicide, medical comorbidities, and family caregiving burden. Because it can take many months to identify an effective treatment regimen, it is of utmost importance to shorten the window of time and identify early on what medications and dosages will work effectively for individuals having depression. Late-life depression (LLD) has been associated with greater burden of age-related changes (eg, atrophy, white matter ischemic changes, and functional connectivity). Depression in midlife has been shown to alter affective reactivity and regulation, and functional magnetic resonance imaging (fMRI) studies in LLD have replicated the same abnormalities. Effective treatment can normalize these alterations. This article provides a review of the current literature using structural and functional neuroimaging to identify MRI predictors of treatment response in LLD. The majority of the literature on structural MRI has focused on the vascular depression hypothesis, and studies support the view that loss of brain volume and white matter integrity was associated with poorer treatment outcomes. Studies using fMRI have reported that lower task-based activity in the prefrontal cortex and limbic regions was associated with poorer outcome. These imaging markers may be integrated into clinical decision making to attain better treatment outcomes in the future. PMID:24381231

  11. High Magnetic Field Superconducting Magnet for 400 MHz Nuclear Magnetic Resonance Spectrometer

    Microsoft Academic Search

    Qiuliang Wang; Baozhi Zhao; Shousen Song; Junsheng Cheng; Yi Li; Yuanzhong Lei; Yinming Dai; Shunzhong Chen; Hui Wang; Housheng Wang; Xinning Hu; Chunyan Cui; Haoyang Liu; Zengren Dong; Chunzhong Wang; Zhipeng Ni; Houcheng Huang; Hongjie Zhang; Luguang Yan; Jianghua Wang

    2011-01-01

    A superconducting magnet with the center field of 9.4 T is designed and fabricated for 400 MHz Nuclear Magnetic Resonance. Superconducting coil with NbTi\\/Cu superconducting wire is employed and cooled by re-condensed liquid helium and the magnet system with the clear-bore of 54 mm. The pulsed tube refrigerator with separated valve is employed to cool the magnet system. The superconducting

  12. Purely electric and magnetic dipole resonances in metamaterial dielectric resonators through perturbation theory inspired geometries

    E-print Network

    Campione, Salvatore; Warne, Larry K; Sinclair, Michael B

    2014-01-01

    In this paper we describe a methodology for tailoring the design of metamaterial dielectric resonators, which represent a promising path toward low-loss metamaterials at optical frequencies. We first describe a procedure to decompose the far field scattered by subwavelength resonators in terms of multipolar field components, providing explicit expressions for the multipolar far fields. We apply this formulation to confirm that an isolated high-permittivity cube resonator possesses frequency separated electric and magnetic dipole resonances, as well as a magnetic quadrupole resonance in close proximity to the electric dipole resonance. We then introduce multiple dielectric gaps to the resonator geometry in a manner suggested by perturbation theory, and demonstrate the ability to overlap the electric and magnetic dipole resonances, thereby enabling directional scattering by satisfying the first Kerker condition. We further demonstrate the ability to push the quadrupole resonance away from the degenerate dipole ...

  13. Ellipsoidal Coil for Magnetic Resonance Spectroscopy

    NASA Astrophysics Data System (ADS)

    Hernandez, R.; Rodriguez, A. O.; Salgado, P.; Barrios, F. A.

    2003-09-01

    We developed an ellipse-shaped surface coil for magnetic resonance spectroscopy for a 1.5 T clinical MR Imager. This coil is to be used to obtain spectra from arms and legs. Standard volume and single-loop coils provide a poor signal because they can not be placed close to the region of interest and their shapes do not fit the anatomy of human extremities. The coil design proposed has more anatomical shape which allows to be placed closer to the region of interest. A higher signal-to-noise ratio can then be achieved resulting in better-quality spectra. Spectra from a phantom and from the arm of a healthy volunteer were acquired to show viability. A 1.5 T clinical scanner (Signa LX equipped with V. 5.8, General Electric Medical System) together with standard spin-echo sequences were used to perform all the spectroscopy experiments. This receiver coil can generate high resolution MR spectra of a spectroscopy phantom and is fully compatible with clinical magnetic resonance systems and standard pulse sequences.

  14. Magnetic resonance imaging in acute mastoiditis

    PubMed Central

    Kitzler, Hagen H; Gudziol, Volker; Laniado, Michael; Hahn, Gabriele

    2014-01-01

    Background In cases of suspected mastoiditis, imaging is used to evaluate the extent of mastoid destruction and possible complications. The role of magnetic resonance imaging (MRI) in mastoiditis has not been systematically evaluated. Purpose To assess the diagnostic performance of MRI in patients with suspected acute mastoiditis. Material and Methods Twenty-three patients with suspected acute mastoiditis were included in this retrospective study (15 boys, 8 girls; mean age, 2 years 11 months). All patients were examined on a 1.5?T MRI system. The MRI examination included both enhanced and non-enhanced turbo spin echo (TSE), diffusion-weighted images, and venous time-of-flight magnetic resonance angiography (TOF MRA) for the evaluation of the venous sinuses. Surgical findings, as well as clinical and imaging follow-up were used as the standard of reference. The sensitivity and accuracy of MRI for mastoiditis and subperiosteal abscesses was calculated. Results Twenty (87%) of 23 patients had mastoiditis, and 12 (52%) of 23 patients had a subperiosteal abscess in addition to mastoiditis. Mastoiditis and subperiosteal abscesses were identified by MRI in all cases. Sensitivity for mastoiditis was 100%, specificity was 66%, and accuracy was 86%. Sensitivity for subperiosteal abscesses was 100% and accuracy was 100%. Conclusion Multiparametric MRI has high accuracy for mastoiditis and subperiosteal abscesses. PMID:24778805

  15. Magnetic resonance imaging. Application to family practice.

    PubMed Central

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

    1999-01-01

    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 PMID:10509224

  16. Development of a micro nuclear magnetic resonance system

    Microsoft Academic Search

    Artem Goloshevsky

    2004-01-01

    Application of Nuclear Magnetic Resonance (NMR) to on-line\\/in-line control of industrial processes is currently limited by equipment costs and requirements for installation. A superconducting magnet generating strong fields is the most expensive part of a typical NMR instrument. In industrial environments, fringe magnetic fields make accommodation of NMR instruments difficult. However, a portable, low-cost and low-field magnetic resonance system can

  17. Nuclear magnetic resonance experiments using laser- polarized noble gas

    Microsoft Academic Search

    Glenn Patrick Teen Chung Wong

    2001-01-01

    Three different nuclear magnetic resonance (NMR) experiments using laser-polarized noble gas are reported. The first experiment demonstrates the feasibility of fast low magnetic field (~20 G) magnetic resonance imaging (MRI) with comparable resolution and signal-to-noise of conventional high magnetic field (~1 T) MRI. In addition, advantages of low field imaging over high field imaging are shown for certain applications. The

  18. Ultra-high-field magnetic resonance: Why and when?

    PubMed Central

    Moser, Ewald

    2010-01-01

    This paper briefly summarizes the development of magnetic resonance imaging and spectroscopy in medicine. Aspects of magnetic resonancephysics and -technology relevant at ultra-high magnetic fields as well as current limitations are highlighted. Based on the first promising studies, potential clinical applications at 7 Tesla are suggested. Other aims are to stimulate awareness of the potential of ultra-high field magnetic resonance and to stimulate active participation in much needed basic or clinical research at 7 Tesla or higher. PMID:21160738

  19. The impact of respiratory and cardiac effects on the phase and magnitude of resting-state fMRI signal

    NASA Astrophysics Data System (ADS)

    Chen, Zikuan; Calhoun, Vince

    2011-03-01

    Functional magnetic resonance imaging (fMRI) relies on detecting small changes in signal during brain activities, in presence of various noise, including those caused by respiration and cardiac pulsation. In the resting state, there is no explicit task event except the baseline neuroactivities of awakeness and other unknowns. However, the resting state is accompanied with the cardiac and respiration pulsations, which are the explicit non-neuronal physiological sources of fMRI signals. By recording the respiration and cardiac waveforms in synchrony with the fMRI scanning, we may estimate the physiological modulation artifacts in the fMRI dataset by the temporal correlations between the waveforms and the fMRI signal. In this work, we demonstrate that the respiration and cardiac modulation effects on the magnitude and phase components of the complex fMRI signal, including temporal correlation and time latency. In particular, our results show that: 1) the fMRI phase is slightly more modulated by the physiological modulations than its magnitude counterpart; 2) the fMRI signal (both magnitude and phase) shows 1 to 2s latency to respiration stimulus, and 0 to 1s latency to cardiac stimulus. For physiological artifact removal, we compare the band-stop filtering method with the RETROICOR method and find the former can remove the physiological modulations in a stable and consistent manner in frequency domain (stopping the signature frequencies irrespective of asynchrony.

  20. Magnetic resonance spectroscopy of perpendicularly magnetized Permalloy multilayer disks

    NASA Astrophysics Data System (ADS)

    de Loubens, G.; Naletov, V. V.; Viret, M.; Klein, O.; Hurdequint, H.; Youssef, J. Ben; Boust, F.; Vukadinovic, N.

    2007-05-01

    Using a magnetic resonance force microscope, we compare the ferromagnetic resonance spectra of individual micron size disks with identical diameter, 1?m, but different layer structures. For a disk composed of a single 43.3-nm-thick Permalloy (Py) layer, the lowest energy mode in the perpendicular configuration is the uniform precession. The higher energy modes are standing spin waves confined along the diameter of the disk. For a Cu (30nm)/Py (100nm)/Cu (30nm) multilayer structure, it has been interpreted that the lowest energy mode becomes a precession localized at the Cu/Py interfaces. When the multilayer is changed to Py (100nm)/Cu (10nm)/Py (10nm), this localized mode of the thick layer becomes coupled to the precession of the thin layer.

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

    Microsoft Academic Search

    Gisela E. Hagberg; Marta Bianciardi; Valentina Brainovich; Antonio Maria Cassara; Bruno Maraviglia

    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

  2. Evaluation of a magnetic resonance-compatible dentoalveolar tactile stimulus device

    PubMed Central

    2010-01-01

    Abstract 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 deliver dentoalveolar dynamic pressure stimuli are described. Device testing took place in three settings: a) laboratory testing to assess range of stimulus force intensities, b) dental chair-side to assess reliability, validity and discriminant ability in force-pain relationship; and c) MRI to evaluate magnetic compatibility and ability to evoke brain activation in painfree subjects similar to those described in the literature. Results A novel device capable of delivering valid and reliable dentoalveolar somatosensory stimulation was developed (ICC = 0.89, 0.78-1 [95% CI]). Psychophysical data analysis showed high discriminant ability in differentiating painfree controls from cases with chronic dentoalveolar pain related to deafferenting dental procedures (sensitivity = 100%, specificity = 86.7%, area under ROC curve = 0.99). FMRI results of dentoalveolar dynamic pressure pain in painfree subjects revealed activation of brain areas typically associated with acute pain processing including thalamus, primary/secondary somatosensory, insular and prefrontal cortex. Conclusions A novel psychophysical method to deliver dynamic dentoalveolar pressure stimulation was developed and validated, allowing non-invasive MRI-based exploration of central nervous system function in response to intraoral somatosensation. Background The organization of the trigeminal system is unique as it provides somatosensory innervation to the face, masticatory and oral structures, the majority of the intracranial contents [1] and to specialized structures (tongue, nasal mucosa, auricle, tympanic membrane, cornea and part of the conjunctiva) [2]. Somatic sensory information transmitted by the trigeminal nerve is crucial for normal orofacial function; however, the mechanisms of many chronic pain conditions affecting areas innervated by this sensory system are not well understood [3-5]. The clinical presentation of chronic intraoral pain in the area of a tooth or in a site formally occupied by a tooth with no clinical or radiological signs of pathology, referred to as atypical odontalgia (AO) [6,7], is one such chronic pain condition of particular interest to dentists that is difficult to diagnose and manage. Recent research suggests both peripheral and central nervous system mechanisms being involved in AO pathophysiology [8-10], but the majority of mechanism-based research of patients with AO has focused on the "peripheral aspect" [7]. Functional magnetic resonance imaging (fMRI) is an established research technique to study the central aspects of pain [11]. Of existing neuroimaging techniques, fMRI provides good spatial resolution of cortical and subcortical structures critical in the processing of nociception, acceptable temporal resolution, does not involve ionizing radiation, and can be performed using most MRI systems that already exist in research centers and the community. For these reasons, we sought to develop a protocol that allows us to use this tool to investigate the central mechanisms involved in the processes of intraoral pain arising from the dentoalveolar region. Using this device, our long-term objective is to improve our understanding of the underlying mechanisms of persistent dentoalveolar pain. In the past few years several studies used fMRI to investigate the human trigeminal system [12,13], with a limited subset focusing on intraoral stimulation - specifically on the dentoalveolar processes, such as lip, tongue and teeth stimulation [14] or only teeth [15-17]. Some reasons for scarce literature on this topic may be the technical challenges involved in delivering facial/intraoral stimulation inside a M

  3. Resonant and High Magnetic Available BE

    E-print Network

    Ohta, Shigemi

    .2 resonant scattering resonant and high magneticfield scattering resonant scattering and XMCD resonant and high magneticfield scattering and XMCD BE Beamline equivalent 1 BE is a station running Footnotes: a = Resonant scattering program inactive since summer 2010 b = Resonant and high magneticfield

  4. BROADBAND EXCITATION IN NUCLEAR MAGNETIC RESONANCE

    SciTech Connect

    Tycko, R.

    1984-10-01

    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.

  5. Decreased activation of the lateral geniculate nucleus in a patient with anisometropic amblyopia demonstrated by functional magnetic resonance imaging.

    PubMed

    Miki, Atsushi; Liu, Grant T; Goldsmith, Zachariah G; Liu, Chia-Shang J; Haselgrove, John C

    2003-01-01

    Although postmortem morphological changes in the lateral geniculate nucleus (LGN) have been reported in human amblyopia, LGN function during monocular viewing by amblyopic eyes has not been documented in humans. We used functional magnetic resonance imaging (fMRI) to study monocular visual activation of the LGN in a patient with anisometropic amblyopia. Four normal subjects, a patient with optic neuritis and a patient with anisometropic amblyopia were studied with fMRI at 1.5 T during monocular checkerboard stimulation. Activated areas in the LGN and visual cortex were identified after data processing (motion correction and spatial normalization) with SPM99. In the 4 normal subjects, comparable activation of the LGN and visual cortex was obtained by stimulation of either the right or left eye. In the patient with unilateral optic neuritis, activation of the LGN and visual cortex was markedly decreased when the affected eye was stimulated. Similarly, decreased activation of the LGN as well as the visual cortex by the affected eye was demonstrated in the patient with anisometropic amblyopia. Our preliminary results suggest that activation of the LGN is diminished during monocular viewing by affected eyes in anisometropic amblyopia. fMRI appears to be a feasible method to study LGN activity in human amblyopia. PMID:12913328

  6. Functional magnetic resonance imaging can be used to explore tactile and nociceptive processing in the infant brain

    PubMed Central

    Williams, Gemma; Fabrizi, Lorenzo; Meek, Judith; Jackson, Deborah; Tracey, Irene; Robertson, Nicola; Slater, Rebeccah; Fitzgerald, Maria

    2015-01-01

    Aim Despite the importance of neonatal skin stimulation, little is known about activation of the newborn human infant brain by sensory stimulation of the skin. We carried out functional magnetic resonance imaging (fMRI) to assess the feasibility of measuring brain activation to a range of mechanical stimuli applied to the skin of neonatal infants. Methods We studied 19 term infants with a mean age of 13 days. Brain activation was measured in response to brushing, von Frey hair (vFh) punctate stimulation and, in one case, nontissue damaging pinprick stimulation of the plantar surface of the foot. Initial whole brain analysis was followed by region of interest analysis of specific brain areas. Results Distinct patterns of functional brain activation were evoked by brush and vFh punctate stimulation, which were reduced, but still present, under chloral hydrate sedation. Brain activation increased with increasing stimulus intensity. The feasibility of using pinprick stimulation in fMRI studies was established in one unsedated healthy full-term infant. Conclusion Distinct brain activity patterns can be measured in response to different modalities and intensities of skin sensory stimulation in term infants. This indicates the potential for fMRI studies in exploring tactile and nociceptive processing in the infant brain. PMID:25358870

  7. Optimal control technique for magnet design in inside-out nuclear magnetic resonance

    Microsoft Academic Search

    Bruno Luong; Jaideva C. Goswami; Apo Sezginer; Dylan Davies

    2001-01-01

    The magnets used in a family of inside-out nuclear magnetic resonance (NMR) well-logging tools usually consist of several segments of magnet materials, with each segment magnetized differently. In a tool, the magnet is surrounded with a nonlinear magnetic material, such as ferrite or steel, that is primarily used in the RF coil or in shielding the electronic components from strong

  8. Nuclear magnetic resonance technology in acupoint catgut embedding therapy for the treatment of menopausal panic disorder: its applications

    NASA Astrophysics Data System (ADS)

    Chen, Gui-zhen; Zhang, Sha-sha; Xu, Yun-xiang; Wang, Xiao-yun

    2012-03-01

    Nuclear Magnetic Resonance (NMR) is a diagnostic method which is non-invasive and non-ionizing irradiative to the human body. It not only suits structural, but also functional imaging. The NMR technique develops rapidly in its application in life science, which has become the hotspot in recent years. Menopausal panic disorder (MPD) is a typical psychosomatic disease during climacteric period, which may affect physical and mental health. Looking for a convenient, effective, and safe method, which is free of toxic-side effects to control the disease, is a modern medical issue. Based on reviewing the etiology and pathogenesis of MPD according to dual traditional Chinese medicine (TCM) and western medicine, further analyzed the advantages and principles for selecting acupoint prescription by tonifying kidney and benefiting marrow therapy for acupoint catgut-embedding to this disease. The application of Nuclear Magnetic Resonance Spectroscopy (NMRS) and Magnetic Resonance Imaging (MRI) technologies in mechanism research on acupoint catgut embedding for the treatment of MPD was discussed. It's pointed out that this intervention method is safe and effective to treat MPD. Breakthrough will be achieved from the research of the selection of acupoint prescription and therapeutic mechanism of acupoint catgut embedding for the treatment of menopausal panic disorder by utilizing the Functional Nuclear Magnetic Resonance Imaging (fMRI) and Metabonomics technologies.

  9. Nuclear magnetic resonance technology in acupoint catgut embedding therapy for the treatment of menopausal panic disorder: its applications

    NASA Astrophysics Data System (ADS)

    Chen, Gui-zhen; Zhang, Sha-sha; Xu, Yun-xiang; Wang, Xiao-yun

    2011-11-01

    Nuclear Magnetic Resonance (NMR) is a diagnostic method which is non-invasive and non-ionizing irradiative to the human body. It not only suits structural, but also functional imaging. The NMR technique develops rapidly in its application in life science, which has become the hotspot in recent years. Menopausal panic disorder (MPD) is a typical psychosomatic disease during climacteric period, which may affect physical and mental health. Looking for a convenient, effective, and safe method, which is free of toxic-side effects to control the disease, is a modern medical issue. Based on reviewing the etiology and pathogenesis of MPD according to dual traditional Chinese medicine (TCM) and western medicine, further analyzed the advantages and principles for selecting acupoint prescription by tonifying kidney and benefiting marrow therapy for acupoint catgut-embedding to this disease. The application of Nuclear Magnetic Resonance Spectroscopy (NMRS) and Magnetic Resonance Imaging (MRI) technologies in mechanism research on acupoint catgut embedding for the treatment of MPD was discussed. It's pointed out that this intervention method is safe and effective to treat MPD. Breakthrough will be achieved from the research of the selection of acupoint prescription and therapeutic mechanism of acupoint catgut embedding for the treatment of menopausal panic disorder by utilizing the Functional Nuclear Magnetic Resonance Imaging (fMRI) and Metabonomics technologies.

  10. The Nobel Prize in Medicine for Magnetic Resonance Imaging

    ERIC Educational Resources Information Center

    Fry, Charles G.

    2004-01-01

    Nobel Prize in Medicine awarded in December 2003 to chemist Paul C. Lauterbur and physicist Peter Mansfield for the development of magnetic resonance imaging (MRI), a long overdue recognition of the huge impact MRI has had in medical diagnostics and research is mentioned. MRI was derived, and remains an extension of nuclear magnetic resonance

  11. Sodium Magnetic Resonance Imaging: From Research to Clinical Use

    E-print Network

    Ouwerkerk, Ronald

    Sodium Magnetic Resonance Imaging: From Research to Clinical Use Ronald Ouwerkerk, PhD INTRODUCTION. Sodium MRI is no longer a stand- alone modality with 1 H MRI used only as a scout image. Instead, 23 Na the properties of this nu- cleus and what imaging techniques can be used to observe it. SODIUM-MAGNETIC RESONANCE

  12. A unitary parallel filter bank approach to magnetic resonance tomography

    NASA Astrophysics Data System (ADS)

    Binz, Ernst; Schempp, Walter

    2000-05-01

    The purpose of the present paper is to establish a unitary parallel multichannel filter bank approach to clinical magnetic resonance tomography and magnetic resonance microscopy. The approach which is based on the Stern-Gerlach filter explains the high resolution capabilities of these non-invasive cross-sectional imaging modalities which revolutionized the field of clinical diagnostics.

  13. Reduction of motion artifacts in magnetic resonance diffusion imaging

    Microsoft Academic Search

    Archie Chih-Ching Chu

    2000-01-01

    Nuclear magnetic resonance (NMR) diffusion is capable of probing molecular displacement in vivo in a micrometer range. The clinical application of diffusion magnetic resonance imaging (MRI) is used for early detecting acute stroke, and it may be a sensitive monitor of early response to cancer treatments. NMR diffusion techniques are sensitive to Brownian motion, but also enhance bulk-motion artifacts in

  14. The application of magnetic resonance in spinal cord disorders

    Microsoft Academic Search

    M Perovitch

    1987-01-01

    The introduction of the proton magnetic resonance imaging into clinical practice shows significant diagnostic potentials, and throws a new light on pathological changes involving the spinal cord, in particular on those related to trauma and its sequelae. The initial experience concerning the use of the proton magnetic resonance imaging in 28 patients, in whom paraplegia or quadriplegia developed following an

  15. Equipotential line method for magnetic resonance electrical impedance tomography

    Microsoft Academic Search

    Ohin Kwon; June-Yub Lee; Jeong-Rock Yoon

    2002-01-01

    We consider magnetic resonance electrical impedance tomography, which aims to reconstruct the conductivity distribution using the internal current density furnished by magnetic resonance imaging. We show the uniqueness of the conductivity reconstruction with one measurement imposing the Dirichlet boundary condition. We also propose a fast non-iterative numerical algorithm for the conductivity reconstruction using the internal current vector information. The algorithm

  16. Equipotential line metho df or magnetic resonance electrical impedance tomography

    Microsoft Academic Search

    Ohin Kwon; J une-Yub Lee; Jeong-Rock Yoon

    2002-01-01

    We consider magnetic resonance electrical impedance tomography, which aims to reconstruct the conductivity distribution using the internal current density furnished by magnetic resonance imaging. We show the uniqueness of the conductivity reconstruction with one measurement imposing the Dirichlet boundary condition. And we propose a fast non-iterative numerical algorithm for the conductivity reconstruction using the internal current vector information. The algorithm

  17. Nuclear magnetic resonance in environmental engineering: principles and applications

    Microsoft Academic Search

    P. N. L. Lens; M. A. Hemminga

    1998-01-01

    This paper gives an introduction to nuclear magnetic resonance spectroscopy (NMR) and magnetic resonance imaging (MRI) in relation to applications in the field of environmental science and engineering. The underlying principles of high resolution solution and solid state NMR, relaxation time measurements and imaging are presented. Then, the use of NMR is illustrated and reviewed in studies of biodegradation and

  18. Nuclear Magnetic Resonance Experiments using Laser-Polarized Noble Gas

    E-print Network

    Walsworth, Ronald L.

    Nuclear Magnetic Resonance Experiments using Laser-Polarized Noble Gas A thesis presented by Glenn Gas Abstract Three different nuclear magnetic resonance (NMR) experiments using laser- polarized noble.e., the probability that a spin has not changed sign up to time t) in the diffusion of laser-polarized noble gas

  19. Diagnosis of hematogenous pyogenic vertebral osteomyelitis by magnetic resonance imaging

    Microsoft Academic Search

    S. P. Meyers; S. N. Wiener

    1991-01-01

    The clinical information and imaging data from 27 patients with hematogenous pyogenic vertebral osteomyelitis were reviewed. All patients had roentgenographic and magnetic resonance imaging examinations. Seventeen patients had computed tomograms; 17 had technetium Tc 99m medronate bone scans; and seven had gallium citrate Ga 67 scans. Magnetic resonance imaging, when used as a part of the initial radiologic evaluation, detected

  20. Magnetic resonance tracking of fluorescent nanodiamond fabrication

    NASA Astrophysics Data System (ADS)

    Shames, A. I.; Osipov, V. Yu; Boudou, J. P.; Panich, A. M.; von Bardeleben, H. J.; Treussart, F.; Vul’, A. Ya

    2015-04-01

    Magnetic resonance techniques (electron paramagnetic resonance (EPR) and nuclear magnetic resonance (NMR)) are used for tracking the multi-stage process of the fabrication of fluorescent nanodiamonds (NDs) produced by high-energy electron irradiation, annealing, and subsequent nano-milling. Pristine commercial high pressure and high temperature microdiamonds (MDs) with mean size 150??m contain ~5? × ?1018?spins/g of singlet (S = 1/2) substitutional nitrogen defects P1, as well as sp3 C–C dangling bonds in the crystalline lattice. The half-field X-band EPR clearly shows (by the appearance of the intense ‘forbidden’ g = 4.26 line) that high-energy electron irradiation and annealing of MDs induce a large amount (~5? × ?1017?spins/g) of triplet (S = 1) magnetic centers, which are identified as negatively charged nitrogen vacancy defects (NV?). This is supported by EPR observations of the ‘allowed’ transitions between Zeeman sublevels of the triplet state. After progressive milling of the fluorescent MDs down to an ultrasubmicron scale (?100?nm), the relative abundance of EPR active NV? defects in the resulting fluorescent NDs (FND) substantially decreases and, vice versa, the content of C-inherited singlet defects correlatively increases. In the fraction of the finest FNDs (mean particle size <20?nm), which are contained in the dried supernatant of ultracentrifuged aqueous dispersion of FNDs, the NV? content is found to be reduced by one order of magnitude whereas the singlet defects content increases up to ~2? × ?1019?spins/g. In addition, another triplet-type defect, which is characterized by the g = 4.00 ‘forbidden’ line, appears. On reduction of the particle size below the 20?nm limit, the ‘allowed’ EPR lines become practically unobservable, whereas the ‘forbidden’ lines remain as a reliable fingerprint of the presence of NV? centers in small ND systems. The same size reduction causes the disappearance of the characteristic hyperfine satellites in the spectra of the P1 centers. We discuss the mechanisms that cause both the strong reduction of the peak intensity of the ‘allowed’ lines in EPR spectra of triplet defects and the transformation of the P1 spectra.

  1. Multivoxel magnetic resonance spectroscopy in a rhizomelic chondrodysplasia punctata case.

    PubMed

    Sigirci, Ahmet; Alkan, Alpay; Kutlu, Ramazan; Gülcan, Hande

    2005-08-01

    A case of a 5-day-old newborn with rhizomelic chondrodysplasia punctata was investigated with multivoxel magnetic resonance spectroscopy, including chemical shift imaging maps, which disclosed a decrease in the choline peak and the choline signal intensity, respectively, in the right cerebral hemisphere. This is the second report of multivoxel magnetic resonance spectroscopy examination of the brain associated with rhizomelic chondrodysplasia punctata in the literature. Multivoxel magnetic resonance spectroscopy with chemical shift imaging maps has the advantage of obtaining more information in a short period of time, which shortens the duration of anesthesia and its associated risks and complications. We suggest that future efforts be directed to evaluating such patients with multivoxel magnetic resonance spectroscopy instead of single-voxel magnetic resonance spectroscopy. PMID:16225820

  2. Plasma-induced magnetic responses during nonlinear dynamics of magnetic islands due to resonant magnetic perturbations

    NASA Astrophysics Data System (ADS)

    Nishimura, Seiya

    2014-12-01

    Resonant magnetic perturbations (RMPs) produce magnetic islands in toroidal plasmas. Self-healing (annihilation) of RMP-induced magnetic islands has been observed in helical systems, where a possible mechanism of the self-healing is shielding of RMP penetration by plasma flows, which is well known in tokamaks. Thus, fundamental physics of RMP shielding is commonly investigated in both tokamaks and helical systems. In order to check this mechanism, detailed informations of magnetic island phases are necessary. In experiments, measurement of radial magnetic responses is relatively easy. In this study, based on a theoretical model of rotating magnetic islands, behavior of radial magnetic fields during the self-healing is investigated. It is confirmed that flips of radial magnetic fields are typically observed during the self-healing. Such behavior of radial magnetic responses is also observed in LHD experiments.

  3. Rotating-frame gradient fields for magnetic resonance imaging and nuclear magnetic resonance in low fields

    DOEpatents

    Bouchard, Louis-Serge; Pines, Alexander; Demas, Vasiliki

    2014-01-21

    A system and method for Fourier encoding a nuclear magnetic resonance (NMR) signal is disclosed. A static magnetic field B.sub.0 is provided along a first direction. An NMR signal from the sample is Fourier encoded by applying a rotating-frame gradient field B.sub.G superimposed on the B.sub.0, where the B.sub.G comprises a vector component rotating in a plane perpendicular to the first direction at an angular frequency .omega.in a laboratory frame. The Fourier-encoded NMR signal is detected.

  4. Magnetic resonance imaging of pancreatitis: An update

    PubMed Central

    Manikkavasakar, Sriluxayini; AlObaidy, Mamdoh; Busireddy, Kiran K; Ramalho, Miguel; Nilmini, Viragi; Alagiyawanna, Madhavi; Semelka, Richard C

    2014-01-01

    Magnetic resonance (MR) imaging plays an important role in the diagnosis and staging of acute and chronic pancreatitis and may represent the best imaging technique in the setting of pancreatitis due to its unmatched soft tissue contrast resolution as well as non-ionizing nature and higher safety profile of intravascular contrast media, making it particularly valuable in radiosensitive populations such as pregnant patients, and patients with recurrent pancreatitis requiring multiple follow-up examinations. Additional advantages include the ability to detect early forms of chronic pancreatitis and to better differentiate adenocarcinoma from focal chronic pancreatitis. This review addresses new trends in clinical pancreatic MR imaging emphasizing its role in imaging all types of acute and chronic pancreatitis, pancreatitis complications and other important differential diagnoses that mimic pancreatitis. PMID:25356038

  5. Lie detection by functional magnetic resonance imaging.

    PubMed

    Lee, Tatia M C; Liu, Ho-Ling; Tan, Li-Hai; Chan, Chetwyn C H; Mahankali, Srikanth; Feng, Ching-Mei; Hou, Jinwen; Fox, Peter T; Gao, Jia-Hong

    2002-03-01

    The accurate detection of deception or lying is a challenge to experts in many scientific disciplines. To investigate if specific cerebral activation characterized feigned memory impairment, six healthy male volunteers underwent functional magnetic resonance imaging with a block-design paradigm while they performed forced-choice memory tasks involving both simulated malingering and under normal control conditions. Malingering that demonstrated the existence and involvement of a prefrontal-parietal-sub-cortical circuit with feigned memory impairment produced distinct patterns of neural activation. Because astute liars feign memory impairment successfully in testing once they understand the design of the measure being employed, our study represents an extremely significant preliminary step towards the development of valid and sensitive methods for the detection of deception. PMID:11835606

  6. Magnetic Resonance Imaging of the Knee

    PubMed Central

    Hash, Thomas W.

    2013-01-01

    Context: Magnetic resonance imaging (MRI) affords high-resolution visualization of the soft tissue structures (menisci, ligaments, cartilage, etc) and bone marrow of the knee. Evidence Acquisition: Pertinent clinical and research articles in the orthopaedic and radiology literature over the past 30 years using PubMed. Results: Ligament tears can be accurately assessed with MRI, but distinguishing partial tears from ruptures of the anterior cruciate ligament (ACL) can be challenging. Determining the extent of a partial tear is often extremely difficult to accurately assess. The status of the posterolateral corner structures, menisci, and cartilage can be accurately evaluated, although limitations in the evaluation of certain structures exist. Patellofemoral joint, marrow, tibiofibular joint, and synovial pathology can supplement physical examination findings and provide definitive diagnosis. Conclusions: MRI provides an accurate noninvasive assessment of knee pathology. PMID:24381701

  7. Musculoskeletal applications of nuclear magnetic resonance

    SciTech Connect

    Moon, K.L. Jr.; Genant, H.K.; Helms, C.A.; Chafetz, N.I.; Crooks, L.E.; Kaufman, L.

    1983-04-01

    Thirty healthy subjects and 15 patients with a variety of musculoskeletal disorders were examined by conventional radiography, computed tomography (CT), and nuclear magnetic resonance (NMR). NMR proved capable of demonstrating important anatomic structures in the region of the lumbosacral spine. Lumbar disk protrusion was demonstrated in three patients with CT evidence of the disease. NMR appeared to differentiate annulus fibrosus from nucleus pulposus in intervertebral disk material. Avascular necrosis of the femoral head was demonstrated in two patients. The cruciate ligaments of the knee were well defined by NMR. Musceles, tendons and ligaments, and blood vessels could be reliably differentiated, and the excellent soft-tissue contrast of NMR proved useful in the evaluation of bony and soft-tissue tumors. NMR holds promise in the evaluation of musculoskeletal disorders.

  8. Magnetic resonance microscopy of osteoporotic bone

    NASA Astrophysics Data System (ADS)

    Toffanin, Renato; Szomolanyi, Pavol; Jellúš, Vladimír; Cova, Maria; Pozzi-Mucelli, Roberto S.; Vittur, Franco

    2000-01-01

    Magnetic resonance microscopy (MRM) may be very useful in the ex vivo study of osteoporosis as non destructive technique able to provide three dimensional information of the bone architecture. However, the trabecular width appears larger in conventional MR images, as the susceptibility effect at the bone-marrow interface causes signal dephasing. Such an effect can be minimized if the echo-time (TE) or voxel size are reduced. The purpose of our research was the development of new MRM techniques that have a potential role in the characterization of trabecular bone architecture. In this study we describe the use of short-TE projection reconstruction MRM for the study of normal and osteoporotic bone explants. This method promises to be more accurate than conventional MRM in the analysis of trabecular bone. In vivo projection reconstruction MR imaging could be applied to evaluate bone architecture and bone quality evolution after space flight exposure. .

  9. In vivo nuclear magnetic resonance imaging

    NASA Technical Reports Server (NTRS)

    Leblanc, A.; Evans, H.; Bryan, R. N.; Johnson, P.; Schonfeld, E.; Jhingran, S. G.

    1984-01-01

    A number of physiological changes have been demonstrated in bone, muscle and blood after exposure of humans and animals to microgravity. Determining mechanisms and the development of effective countermeasures for long duration space missions is an important NASA goal. The advent of tomographic nuclear magnetic resonance imaging (NMR or MRI) gives NASA a way to greatly extend early studies of this phenomena in ways not previously possible; NMR is also noninvasive and safe. NMR provides both superb anatomical images for volume assessments of individual organs and quantification of chemical/physical changes induced in the examined tissues. The feasibility of NMR as a tool for human physiological research as it is affected by microgravity is demonstrated. The animal studies employed the rear limb suspended rat as a model of mucle atrophy that results from microgravity. And bedrest of normal male subjects was used to simulate the effects of microgravity on bone and muscle.

  10. Oxygenation-sensitive cardiovascular magnetic resonance

    PubMed Central

    2013-01-01

    Oxygenation-sensitive cardiovascular magnetic resonance (CMR) is a non-contrast technique that allows the non-invasive assessment of myocardial oxygenation. It capitalizes on the fact that deoxygenated hemoglobin in blood can act as an intrinsic contrast agent, changing proton signals in a fashion that can be imaged to reflect the level of blood oxygenation. Increases in O2 saturation increase the BOLD imaging signal (T2 or T2*), whereas decreases diminish it. This review presents the basic concepts and limitations of the BOLD technique, and summarizes the preclinical and clinical studies in the assessment of myocardial oxygenation with a focus on recent advances. Finally, it provides future directions and a brief look at emerging techniques of this evolving CMR field. PMID:23706167

  11. The magnetic resonance imaging-linac system.

    PubMed

    Lagendijk, Jan J W; Raaymakers, Bas W; van Vulpen, Marco

    2014-07-01

    The current image-guided radiotherapy systems are suboptimal in the esophagus, pancreas, kidney, rectum, lymph node, etc. These locations in the body are not easily accessible for fiducials and cannot be visualized sufficiently on cone-beam computed tomographies, making daily patient set-up prone to geometrical uncertainties and hinder dose optimization. Additional interfraction and intrafraction uncertainties for those locations arise from motion with breathing and organ filling. To allow real-time imaging of all patient tumor locations at the actual treatment position a fully integrated 1.5-T, diagnostic quality, magnetic resonance imaging with a 6-MV linear accelerator is presented. This system must enable detailed dose painting at all body locations. PMID:24931095

  12. Cardiovascular Magnetic Resonance Imaging in Experimental Models

    PubMed Central

    Price, Anthony N.; Cheung, King K.; Cleary, Jon O; Campbell, Adrienne E; Riegler, Johannes; Lythgoe, Mark F

    2010-01-01

    Cardiovascular magnetic resonance (CMR) imaging is the modality of choice for clinical studies of the heart and vasculature, offering detailed images of both structure and function with high temporal resolution. Small animals are increasingly used for genetic and translational research, in conjunction with models of common pathologies such as myocardial infarction. In all cases, effective methods for characterising a wide range of functional and anatomical parameters are crucial for robust studies. CMR is the gold-standard for the non-invasive examination of these models, although physiological differences, such as rapid heart rate, make this a greater challenge than conventional clinical imaging. However, with the help of specialised magnetic resonance (MR) systems, novel gating strategies and optimised pulse sequences, high-quality images can be obtained in these animals despite their small size. In this review, we provide an overview of the principal CMR techniques for small animals for example cine, angiography and perfusion imaging, which can provide measures such as ejection fraction, vessel anatomy and local blood flow, respectively. In combination with MR contrast agents, regional dysfunction in the heart can also be identified and assessed. We also discuss optimal methods for analysing CMR data, particularly the use of semi-automated tools for parameter measurement to reduce analysis time. Finally, we describe current and emerging methods for imaging the developing heart, aiding characterisation of congenital cardiovascular defects. Advanced small animal CMR now offers an unparalleled range of cardiovascular assessments. Employing these methods should allow new insights into the structural, functional and molecular basis of the cardiovascular system. PMID:21331311

  13. Magnetic Resonance Studies of Energy Storage Materials

    NASA Astrophysics Data System (ADS)

    Vazquez Reina, Rafael

    In today's society there is high demand to have access to energy for portable devices in different forms. Capacitors with high performance in small package to achieve high charge/discharge rates, and batteries with their ability to store electricity and make energy mobile are part of this demand. The types of internal dielectric material strongly affect the characteristics of a capacitor, and its applications. In a battery, the choice of the electrolyte plays an important role in the Solid Electrolyte Interphase (SEI) formation, and the cathode material for high output voltage. Electron Paramagnetic Resonance (EPR) and Nuclear Magnetic Resonance (NMR) spectroscopy are research techniques that exploit the magnetic properties of the electron and certain atomic nuclei to determine physical and chemical properties of the atoms or molecules in which they are contained. Both EPR and NMR spectroscopy technique can yield meaningful structural and dynamic information. Three different projects are discussed in this dissertation. First, High energy density capacitors where EPR measurements described herein provide an insight into structural and chemical differences in the dielectric material of a capacitor. Next, as the second project, Electrolyte solutions where an oxygen-17 NMR study has been employed to assess the degree of preferential solvation of Li+ ions in binary mixtures of EC (ethylene carbonate) and DMC (dimethyl carbonate) containing LiPF6 (lithium hexafluo-rophosphate) which may be ultimately related to the SEI formation mechanism. The third project was to study Bismuth fluoride as cathode material for rechargeable batteries. The objective was to study 19F and 7Li MAS NMR of some nanocomposite cathode materials as a conversion reaction occurring during lithiation and delithation of the BiF3/C nanocomposite.

  14. Could magnetic resonance provide in vivo histology?

    PubMed Central

    Dominietto, Marco; Rudin, Markus

    2014-01-01

    The diagnosis of a suspected tumor lesion faces two basic problems: detection and identification of the specific type of tumor. Radiological techniques are commonly used for the detection and localization of solid tumors. Prerequisite is a high intrinsic or enhanced contrast between normal and neoplastic tissue. Identification of the tumor type is still based on histological analysis. The result depends critically on the sampling sites, which given the inherent heterogeneity of tumors, constitutes a major limitation. Non-invasive in vivo imaging might overcome this limitation providing comprehensive three-dimensional morphological, physiological, and metabolic information as well as the possibility for longitudinal studies. In this context, magnetic resonance based techniques are quite attractive since offer at the same time high spatial resolution, unique soft tissue contrast, good temporal resolution to study dynamic processes and high chemical specificity. The goal of this paper is to review the role of magnetic resonance techniques in characterizing tumor tissue in vivo both at morphological and physiological levels. The first part of this review covers methods, which provide information on specific aspects of tumor phenotypes, considered as indicators of malignancy. These comprise measurements of the inflammatory status, neo-vascular physiology, acidosis, tumor oxygenation, and metabolism together with tissue morphology. Even if the spatial resolution is not sufficient to characterize the tumor phenotype at a cellular level, this multiparametric information might potentially be used for classification of tumors. The second part discusses mathematical tools, which allow characterizing tissue based on the acquired three-dimensional data set. In particular, methods addressing tumor heterogeneity will be highlighted. Finally, we address the potential and limitation of using MRI as a tool to provide in vivo tissue characterization. PMID:24454320

  15. Burn injury by nuclear magnetic resonance imaging.

    PubMed

    Eising, Ernst G; Hughes, Justin; Nolte, Frank; Jentzen, Walter; Bockisch, Andreas

    2010-01-01

    Nuclear magnetic resonance imaging has become a standard diagnostic procedure in clinical medicine and is well known to have hazards for patients with pacemaker or metallic foreign bodies. Compared to CT, the frequency of MRI examinations is increasing due to the missing exposure of the patients by X-rays. Furthermore, high-field magnetic resonance tomograph (MRT) with 3 T has entered clinical practice, and 7-T systems are installed in multiple scientific institutions. On the other hand, the possibility of burn injuries has been reported only in very few cases. Based on a clinical finding of a burn injury in a 31-year-old male patient during a routine MRI of the lumbar spine with standard protocol, the MR scanner was checked and the examination was simulated in an animal model. The patient received a third-degree burn injury of the skin of the right hand and pelvis in a small region of skin contact. The subsequent control of the MRI scanner indicated no abnormal values for radiofrequency (RF) and power. In the subsequent animal experiment, comparable injuries could only be obtained by high RF power in a microwave stove. It is concluded that 'tissue loops' resulting from a contact between hand and pelvis must be avoided. With regard to forensic aspects, the need to inform patients of such a minimal risk can be avoided if the patients are adequately positioned using an isolating material between the hands and pelvis. These facts must be emphasized more in the future, if high-field MRI with stronger RF gradients is available in routine imaging. PMID:20630342

  16. Magnetic Resonance Imaging of Pharmacological Systems

    Microsoft Academic Search

    Hanbing Lu; Thomas J. Ross; Elliot A. Stein

    \\u000a With the appropriate hardware, pulse sequences and analysis methods, modern MRI research is able to measure numerous neurobiologically\\u000a relevant parameters including functional activation (fMRI) using blood oxygen level dependent, diffusion tensor imaging –\\u000a either to measure integrity of white matter or to follow white matter fiber tracts, MR spectroscopy, changes in cerebral blood\\u000a flow, cerebral blood volume and oxygen metabolism

  17. Novel Detection Schemes of Nuclear Magnetic Resonance and Magnetic Resonance Imaging: Applications from Analytical Chemistry to Molecular Sensors

    Microsoft Academic Search

    Elad Harel; Leif Schröder; Shoujun Xu

    2008-01-01

    Nuclear magnetic resonance (NMR) is a well-established analytical technique in chemistry. The ability to precisely control the nuclear spin interactions that give rise to the NMR phenomenon has led to revolutionary advances in fields as diverse as protein structure determination and medical diagnosis. Here, we discuss methods for increasing the sensitivity of magnetic resonance experiments, moving away from the paradigm

  18. Controlling interactions between highly magnetic atoms with Feshbach resonances.

    PubMed

    Kotochigova, Svetlana

    2014-09-01

    This paper reviews current experimental and theoretical progress in the study of dipolar quantum gases of ground and meta-stable atoms with a large magnetic moment. We emphasize the anisotropic nature of Feshbach resonances due to coupling to fast-rotating resonant molecular states in ultracold s-wave collisions between magnetic atoms in external magnetic fields. The dramatic differences in the distribution of resonances of magnetic (7)S3 chromium and magnetic lanthanide atoms with a submerged 4f shell and non-zero electron angular momentum is analyzed. We focus on dysprosium and erbium as important experimental advances have been recently made to cool and create quantum-degenerate gases for these atoms. Finally, we describe progress in locating resonances in collisions of meta-stable magnetic atoms in electronic P-states with ground-state atoms, where an interplay between collisional anisotropies and spin-orbit coupling exists. PMID:25221938

  19. A Tool for Classifying Individuals with Chronic Back Pain: Using Multivariate Pattern Analysis with Functional Magnetic Resonance Imaging Data

    PubMed Central

    Callan, Daniel; Mills, Lloyd; Nott, Connie; England, Robert; England, Shaun

    2014-01-01

    Chronic pain is one of the most prevalent health problems in the world today, yet neurological markers, critical to diagnosis of chronic pain, are still largely unknown. The ability to objectively identify individuals with chronic pain using functional magnetic resonance imaging (fMRI) data is important for the advancement of diagnosis, treatment, and theoretical knowledge of brain processes associated with chronic pain. The purpose of our research is to investigate specific neurological markers that could be used to diagnose individuals experiencing chronic pain by using multivariate pattern analysis with fMRI data. We hypothesize that individuals with chronic pain have different patterns of brain activity in response to induced pain. This pattern can be used to classify the presence or absence of chronic pain. The fMRI experiment consisted of alternating 14 seconds of painful electric stimulation (applied to the lower back) with 14 seconds of rest. We analyzed contrast fMRI images in stimulation versus rest in pain-related brain regions to distinguish between the groups of participants: 1) chronic pain and 2) normal controls. We employed supervised machine learning techniques, specifically sparse logistic regression, to train a classifier based on these contrast images using a leave-one-out cross-validation procedure. We correctly classified 92.3% of the chronic pain group (N?=?13) and 92.3% of the normal control group (N?=?13) by recognizing multivariate patterns of activity in the somatosensory and inferior parietal cortex. This technique demonstrates that differences in the pattern of brain activity to induced pain can be used as a neurological marker to distinguish between individuals with and without chronic pain. Medical, legal and business professionals have recognized the importance of this research topic and of developing objective measures of chronic pain. This method of data analysis was very successful in correctly classifying each of the two groups. PMID:24905072

  20. Efficient heteronuclear dipolar decoupling in solid-state nuclear magnetic resonance at rotary resonance conditions

    NASA Astrophysics Data System (ADS)

    Paul, Subhradip; Mithu, Venus Singh; Kurur, Narayanan D.; Madhu, P. K.

    2010-03-01

    We introduce here a heteronuclear dipolar decoupling scheme in solid-state nuclear magnetic resonance that performs efficiently at the rotary resonance conditions, where otherwise dipolar couplings are re-introduced. Results are shown proving the efficiency of this scheme at two magnetic fields under magic-angle spinning frequencies of 30 and 20 kHz.

  1. Optically Detected Magnetic Resonance (ODMR) of Triplet States in Photosynthesis

    Microsoft Academic Search

    Arnold J. Hoff

    The triplet state of aromatic molecules and of polyenes is a versatile probe of molecular structure and of the interactions\\u000a with the environment, through the zero-field splitting (ZFS) parameters and the sublevel decay rates. These tripletproperties\\u000a can be determined accurately with magnetic resonance. Optical detection of magnetic resonance (ODMR) is often advantageous\\u000a because it pairs the frequency resolution of magnetic

  2. Neurochemistry of Drug Action: Insights from Proton Magnetic Resonance Spectroscopic Imaging And Their Relevance to Addiction

    PubMed Central

    Licata, Stephanie C.; Renshaw, Perry F.

    2011-01-01

    Proton magnetic resonance spectroscopy (1H MRS) is a non-invasive imaging technique that permits measurement of particular compounds or metabolites within the tissue of interest. In the brain, 1H MRS provides a snapshot of the neurochemical environment within a defined volume of interest. A search of the literature demonstrates the widespread utility of this technique for characterizing tumors, tracking the progress of neurodegenerative disease, and for understanding the neurobiological basis of psychiatric disorders. As of relatively recently, 1H MRS has found its way into substance abuse research, and it is beginning to become recognized as a valuable complement in the brain imaging toolbox that also contains positron emission tomography (PET), single photon emission computed tomography (SPECT), and functional magnetic resonance imaging (fMRI). Drug abuse studies employing 1H MRS have identified a number biochemical changes in the brain. The most consistent alterations across drug class were reductions in N-acetylaspartate and elevations in myo-inositol, while changes in choline, creatine, and amino acid transmitters also were abundant. Together, the studies discussed herein provide evidence that drugs of abuse may have a profound impact on neuronal health, energy metabolism and maintenance, inflammatory processes, cell membrane turnover, and neurotransmission, and these biochemical changes may underlie the neuropathology within brain tissue that subsequently gives rise to the cognitive and behavioral impairments associated with drug addiction. PMID:20201852

  3. Cardiac imaging using gated magnetic resonance

    SciTech Connect

    Lanzer, P.; Botvinick, E.H.; Schiller, N.B.

    1984-01-01

    To overcome the limitations of magnetic resonance (MR) cardiac imaging using nongated data acquisition, three methods for acquiring a gating signal, which could be applied in the presence of a magnetic field, were tested; an air-filled plethysmograph, a laser-Doppler capillary perfusion flowmeter, and an electrocardiographic gating device. The gating signal was used for timing of MR imaging sequences (IS). Application of each gating method yielded significant improvements in structural MR image resolution of the beating heart, although with both plethysmography and laser-Doppler velocimetry it was difficult to obtain cardiac images from the early portion of the cardiac cycle due to an intrinsic delay between the ECG R wave and peripheral detection of the gating signal. Variations in the temporal relationship between the R wave and plethysmographic and laser-Doppler signals produced inconsistencies in the timing of IS. Since the ECG signal is virtually free of these problems, the preferable gating technique is IS synchronization with an electrocardiogram. The gated images acquired with this method provide sharp definition of internal cardiac morphology and can be temporarily referenced to end diastole and end systole or intermediate points.

  4. Contrast mechanisms in magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Lepage, M.; Gore, J. C.

    2004-01-01

    The first publications describing gel dosimetry used magnetic resonance imaging to detect changes in the proton longitudinal relaxation rate of a gel infused with ferrous ions and irradiated with ionizing radiation. Later, different gel dosimeter systems were proposed that are based on the free-radical polymerization of monomers dispersed in a gel matrix. In these polymer gels, changes in transverse relaxation rates were shown to be dependent on the absorbed dose. More recently, contrast in MR images based on the exchange of magnetization between polymer and water protons, following saturation of the polymer protons, has been exploited in polymer gel dosimeters. In addition, variations in relaxation times in the rotating frame (T1?) have been shown to produce contrast in MR images of irradiated polymer gel dosimeters. The signal and contrast in MR images may be manipulated to reflect a variety of these and other processes within an irradiated sample, An attempt is made here to provide an overview of the main different types of MRI contrast that may be used in gel dosimetry and, where possible, to relate this contrast to the nature of the chemical processes and structural changes that occur within the gels following the absorption of ionizing radiation.

  5. Thoracic magnetic resonance imaging: pulmonary thromboembolism.

    PubMed

    Fink, Christian; Henzler, Thomas; Shirinova, Aysel; Apfaltrer, Paul; Wasser, Klaus

    2013-05-01

    Ongoing technical developments have substantially improved the potential of magnetic resonance imaging (MRI) in the assessment of the pulmonary circulation. These developments includes improved magnet and hardware design, new k-space sampling techniques (ie, parallel imaging), and alternative contrast materials. With these techniques, not only can pulmonary vessels be visualized by MR angiography with high spatial resolution but also the perfusion of the lungs and its changes in relation to pulmonary thromboembolism (PE) can be assessed. Considering venous thromboembolism as a systemic disease, MR venography might be added for the diagnosis of underlying deep venous thrombosis. A unique advantage of MRI over other imaging tests is its potential to evaluate changes in cardiac function as a result of obstruction of the pulmonary circulation, which may have a significant impact on patient monitoring and treatment. Finally, MRI does not involve radiation, which is advantageous, especially in young patients. Over the years, a number of studies have shown promising results not only for MR angiography but also for MRI of lung perfusion and for MR venography. This review article summarizes and discusses the current evidence on pulmonary MRI for patients with suspected PE. PMID:23545949

  6. Investigation of facial recognition memory and happy and sad facial expression perception: an fMRI study

    Microsoft Academic Search

    Mary L. Phillips; Edward T. Bullmore; Robert Howard; Peter W. R. Woodruff; Ian C. Wright; Steven C. R. Williams; Andrew Simmons; Christopher Andrew; Michael Brammer; Anthony S. David

    1998-01-01

    We investigated facial recognition memory (for previously unfamiliar faces) and facial expression perception with functional magnetic resonance imaging (fMRI). Eight healthy, right-handed volunteers participated. For the facial recognition task, subjects made a decision as to the familiarity of each of 50 faces (25 previously viewed; 25 novel). We detected signal increase in the right middle temporal gyrus and left prefrontal

  7. Schizophrenic subjects activate dorsolateral prefrontal cortex during a working memory task, as measured by fMRI

    Microsoft Academic Search

    Dara S Manoach; Venkatassen Thangaraj; Meghan M Searl; Donald C Goff; Elkan Halpern; Clifford B Saper; Steven Warach

    1999-01-01

    Background: Neuroimaging studies of schizophrenic subjects performing working memory (WM) tasks have demonstrated a relative hypoactivity of prefrontal cortex compared with normal subjects.Methods: Using functional magnetic resonance imaging (fMRI), we compared dorsolateral prefrontal cortex (DLPFC) activation in 12 schizophrenic and 10 normal subjects during rewarded performance of a WM task. Subjects performed a modified version of the Sternberg Item Recognition

  8. FMRI Brain Activation in a Finnish Family with Specific Language Impairment Compared with a Normal Control Group

    ERIC Educational Resources Information Center

    Hugdahl, Kenneth; Gundersen, Hilde; Brekke, Cecilie; Thomsen, Tormod; Rimol, Lars Morten; Ersland, Lars; Niemi, Jussi

    2004-01-01

    The aim of the present study was to investigate differences in brain activation in a family with SLI as compared to intact individuals with normally developed language during processing of language stimuli. Functional magnetic resonance imaging (fMRI) was used to monitor changes in neuronal activation in temporal and frontal lobe areas in 5…

  9. Evaluation and optimization of fMRI single-subject processing pipelines with NPAIRS and second-level CVA

    Microsoft Academic Search

    Jing Zhang; Jon R. Anderson; Lichen Liang; Sujit K. Pulapura; Lael Gatewood; David A. Rottenberg; Stephen C. Strother

    2009-01-01

    In functional magnetic resonance imaging (fMRI) analysis, although the univariate general linear model (GLM) is currently the dominant approach to brain activation detection, there is growing interest in multivariate approaches such as principal component analysis, canonical variate analysis (CVA), independent component analysis and cluster analysis, which have the potential to reveal neural networks and functional connectivity in the brain. To

  10. Changes in Brain Activation Induced by the Training of Hypothesis Generation Skills: An fMRI Study

    ERIC Educational Resources Information Center

    Kwon, Yong-Ju; Lee, Jun-Ki; Shin, Dong-Hoon; Jeong, Jin-Su

    2009-01-01

    The aim of the present study is to investigate the learning-related changes in brain activation induced by the training of hypothesis generation skills regarding biological phenomena. Eighteen undergraduate participants were scanned twice with functional magnetic resonance imaging (fMRI) before and after training over a period of 2 months. The…

  11. Source Monitoring 15 Years Later: What Have We Learned from fMRI about the Neural Mechanisms of Source Memory?

    ERIC Educational Resources Information Center

    Mitchell, Karen J.; Johnson, Marcia K.

    2009-01-01

    Focusing primarily on functional magnetic resonance imaging (fMRI), this article reviews evidence regarding the roles of subregions of the medial temporal lobes, prefrontal cortex, posterior representational areas, and parietal cortex in source memory. In addition to evidence from standard episodic memory tasks assessing accuracy for neutral…

  12. Exploring Possible Neural Mechanisms of Intelligence Differences Using Processing Speed and Working Memory Tasks: An fMRI Study

    ERIC Educational Resources Information Center

    Waiter, Gordon D.; Deary, Ian J.; Staff, Roger T.; Murray, Alison D.; Fox, Helen C.; Starr, John M.; Whalley, Lawrence J.

    2009-01-01

    To explore the possible neural foundations of individual differences in intelligence test scores, we examined the associations between Raven's Matrices scores and two tasks that were administered in a functional magnetic resonance imaging (fMRI) setting. The two tasks were an n-back working memory (N = 37) task and inspection time (N = 47). The…

  13. Is Broca's area involved in the processing of passive sentences? An event-related fMRI study

    Microsoft Academic Search

    Satoru Yokoyama; Jobu Watanabe; Kazuki Iwata; Naho Ikuta; Tomoki Haji; Nobuo Usui; Masato Taira; Tadao Miyamoto; Wataru Nakamura; Shigeru Sato; Kaoru Horie; Ryuta Kawashima

    2007-01-01

    We used functional magnetic resonance imaging (fMRI) to investigate whether activation in Broca's area is greater during the processing of passive versus active sentences in the brains of healthy subjects. Twenty Japanese native speakers performed a visual sentence comprehension task in which they were asked to read a visually presented sentence and to identify the agent or the patient in

  14. Human Amygdala Activation during Conditioned Fear Acquisition and Extinction: a Mixed-Trial fMRI Study

    Microsoft Academic Search

    Kevin S. LaBar; J. Christopher Gatenby; John C. Gore; Joseph E. LeDoux; Elizabeth A. Phelps

    1998-01-01

    Echoplanar functional magnetic resonance imaging (fMRI) was used in normal human subjects to investigate the role of the amygdala in conditioned fear acquisition and extinction. A simple discrimination procedure was employed in which activation to a visual cue predicting shock (CS+) was compared with activation to another cue presented alone (CS?). CS+ and CS? trial types were intermixed in a

  15. Is Broca's Area Involved in the Processing of Passive Sentences? An Event-Related fMRI Study

    ERIC Educational Resources Information Center

    Yokoyama, Satoru; Watanabe, Jobu; Iwata, Kazuki; Ikuta, Naho; Haji, Tomoki; Usui, Nobuo; Taira, Masato; Miyamoto, Tadao; Nakamura, Wataru; Sato, Shigeru; Horie, Kaoru; Kawashima, Ryuta

    2007-01-01

    We used functional magnetic resonance imaging (fMRI) to investigate whether activation in Broca's area is greater during the processing of passive versus active sentences in the brains of healthy subjects. Twenty Japanese native speakers performed a visual sentence comprehension task in which they were asked to read a visually presented sentence…

  16. Functional Neuroanatomy of Emotion: A Meta-Analysis of Emotion Activation Studies in PET and fMRI

    Microsoft Academic Search

    K. Luan Phan; Tor Wager; Stephan F. Taylor; Israel Liberzon

    2002-01-01

    Neuroimagingstudies with positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) have begun to describe the functional neuroanatomy of emotion. Taken separately, specific studies vary in task dimensions and in type(s) of emotion studied and are limited by statistical power and sensitivity. By examining findings across studies, we sought to determine if common or segregated patterns of activations exist

  17. Improvements in Magnetic Resonance Imaging Excitation Pulse Design

    E-print Network

    Goyal, Vivek K

    Improvements in Magnetic Resonance Imaging Excitation Pulse Design by Adam Charles Zelinski magnetic spins are tilted by only a small amount, pulse transmission may be interpreted as depositing by . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Terry P. Orlando Chairman, Department Committee on Graduate Students #12;2 #12;Improvements in Magnetic

  18. Insertable biplanar gradient coils for magnetic resonance imaging

    Microsoft Academic Search

    M. A. Martens; L. S. Petropoulos; R. W. Brown; J. H. Andrews; M. A. Morich; J. L. Patrick

    1991-01-01

    Insertable planar gradient coils offer the potential for significant performance increases in magnetic resonance imaging through higher gradient strength and shorter rise times. Using variational methods to minimize inductance, and thereby to optimize switching speeds, we have analyzed and constructed a biplanar y-gradient coil for insertion into a solenoidal magnet system where z is the magnet axis. We have also

  19. Tuning Coler Magnetic Current Apparatus with Magneto-Acoustic Resonance

    NASA Astrophysics Data System (ADS)

    Ludwig, Thorsten

    An attempt was made to tune the Coler magnetic current apparatus with the magneto acoustic resonance of the magnetic rods. Measurements with a replica of the famous Coler "Magnetstromapparat" were conducted. In order to tune the acoustic, magnetic and electric resonance circuits of the Coler device the magneto-acoustic resonance was measured with a frequency scan through a function generator and a lock-in amplifier. The frequency generator was powering a driving coil, while the lock-in was connected to a pickup coil. Both coils were placed on a magnetic rod. Resonances were observed up to the 17th harmonic. The quality Q of the observed resonances was 270. To study the magneto-acoustic resonance in the time domain a pair of Permendur rods were employed. The magneto-acoustic resonances of the Permendur rods were observed with an oscilloscope. Spectra of the magneto acoustic resonance were measured for the Permendur rods and for a Coler replica magnet in the frequency range from 25 kHz to 380 kHz. The next step was to bring the resonances of the Permendur rods close together so that they overlap. The 10thharmonic was chosen because it was close to the 180 kHz that Hans Coler related to ferromagnetism. Further more magneto-acoustic coupling between the Permendur rods was studied. Finally the question was explored if Hans Coler converted vacuum fluctuations via magnetic and acoustic resonance into electricity. There is a strong connection between magnetism and quantum field zero point energy (ZPE). An outlook is given on next steps in the experiments to unveil the working mechanism of the Coler magnetic current apparatus.

  20. Delay correlation subspace decomposition algorithm and its application in fMRI.

    PubMed

    Chen, Huafu; Yao, Dezhong; Chen, Wufan; Chen, Lin

    2005-12-01

    This paper reports a new delay subspace decomposition (DSD) algorithm. Instead of using the canonical zero-delay correlation matrix, the new DSD algorithm introduces a delay into the correlation matrix of the subspace decomposition to suppress noises in the data. The algorithm is applied to functional magnetic resonance imaging (fMRI) to detect the regions of focal activities in the brain. The efficiency is evaluated by comparing with independent component analysis and principal component analysis method of fMRI. PMID:16350921

  1. GMAC: a Matlab toolbox for spectral Granger causality analysis of fMRI data.

    PubMed

    Tana, Maria Gabriella; Sclocco, Roberta; Bianchi, Anna Maria

    2012-10-01

    Investigation of causal interactions within brain networks using Granger causality analysis (GCA) is a key challenge in studying neural activity on the basis of functional magnetic resonance imaging (fMRI). The article describes an open-source software toolbox GMAC (Granger multivariate autoregressive connectivity) implementing multivariate spectral GCA. Available features are: fMRI data importing/exporting, network nodes definition, time series preprocessing, multivariate autoregressive modeling, spectral Granger causality indexes estimation, statistical significance assessment using surrogate data, network analysis and visualization of connectivity results. All functions have been integrated into a user-friendly graphical interface developed in the Matlab environment, easily accessible to both technical and clinical users. PMID:22925560

  2. fMRI tracks reductions in repetitive behaviors in autism: two case studies.

    PubMed

    Dichter, Gabriel S; Sikich, Linmarie; Mahorney, Steve; Felder, Jennifer N; Lam, Kristen S L; Turner-Brown, Lauren; Bodfish, James

    2010-08-01

    Autism is characterized by abnormal prefrontal brain activation during cognitive control, a potential biomarker of repetitive behaviors. In this proof-of-principle study, functional magnetic resonance imaging (fMRI) was used to examine brain activity during an oddball task in two high-functioning males with autism before and after 12 weeks of treatment with citalopram, a selective serotonin reuptake inhibitor. One participant showed marked reductions in repetitive behaviors whereas the other showed mild worsening. Brain activation in relevant prefrontal regions increased in only the participant whose repetitive behavior symptoms improved. These findings suggest that fMRI may elucidate potential mechanisms of action of targeted autism interventions. PMID:20178033

  3. Purcell factor of Mie resonators featuring electric and magnetic modes

    E-print Network

    Zambrana-Puyalto, Xavier

    2015-01-01

    We present a modal approach to compute the Purcell factor in Mie resonators exhibiting both electric and magnetic resonances. The analytic expressions of the normal modes are used to calculate the effective volumes. We show that important features of the effective volume can be predicted thanks to the translation-addition coefficients of a displaced dipole. Using our formalism, it is easy to see that, in general, the Purcell factor of Mie resonators is not dominated by a single mode, but rather by a large superposition. Finally we consider a silicon resonator homogeneously doped with electric dipolar emitters, and we show that the average electric Purcell factor dominates over the magnetic one.

  4. Rhythmic 3-4Hz discharge is insufficient to produce cortical BOLD fMRI decreases in generalized seizures.

    PubMed

    Youngblood, Mark W; Chen, William C; Mishra, Asht M; Enamandram, Sheila; Sanganahalli, Basavaraju G; Motelow, Joshua E; Bai, Harrison X; Frohlich, Flavio; Gribizis, Alexandra; Lighten, Alexis; Hyder, Fahmeed; Blumenfeld, Hal

    2015-04-01

    Absence seizures are transient episodes of impaired consciousness accompanied by 3-4 Hz spike-wave discharge on electroencephalography (EEG). Human functional magnetic resonance imaging (fMRI) studies have demonstrated widespread cortical decreases in the blood oxygen-level dependent (BOLD) signal that may play an important role in the pathophysiology of these seizures. Animal models could provide an opportunity to investigate the fundamental mechanisms of these changes, however they have so far failed to consistently replicate the cortical fMRI decreases observed in human patients. This may be due to important differences between human seizures and animal models, including a lack of cortical development in rodents or differences in the frequencies of rodent (7-8 Hz) and human (3-4 Hz) spike-wave discharges. To examine the possible contributions of these differences, we developed a ferret model that exhibits 3-4 Hz spike-wave seizures in the presence of a sulcated cortex. Measurements of BOLD fMRI and simultaneous EEG demonstrated cortical fMRI increases during and following spike-wave seizures in ferrets. However unlike human patients, significant fMRI decreases were not observed. The lack of fMRI decreases was consistent across seizures of different durations, discharge frequencies, and anesthetic regimes, and using fMRI analysis models similar to human patients. In contrast, generalized tonic-clonic seizures under the same conditions elicited sustained postictal fMRI decreases, verifying that the lack of fMRI decreases with spike-wave was not due to technical factors. These findings demonstrate that 3-4 Hz spike-wave discharge in a sulcated animal model does not necessarily produce fMRI decreases, leaving the mechanism for this phenomenon open for further investigation. PMID:25562830

  5. Magnetic resonance imaging of the central nervous system

    SciTech Connect

    Brant-Zawadzki, M.; Norman, D.

    1986-01-01

    This book provides an introduction to magnetic resonance imaging (MRI) of disorders of the central nervous system, spine, neck, and nasopharynx. The book provides guidance in performing and interpreting MRI studies for specific clinical problems. Images showing pathologic findings for various disorders and demonstrating how abnormalities detected in MRI scans can aid both in differential diagnosis and clinical staging are shown. The book summarizes the basic principles of MRI and describes equipment components and contrast agents. Explanations of common artifacts and pitfalls in image interpretation and of pathophysiologic correlates of signal alterations in magnetic resonance imaging are given. A review of the principles and potential applications of magnetic resonance spectroscopy is also included.

  6. Functional magnetic resonance imaging study of Piaget's conservation-of-number task in preschool and school-age children: a neo-Piagetian approach.

    PubMed

    Houdé, Olivier; Pineau, Arlette; Leroux, Gaëlle; Poirel, Nicolas; Perchey, Guy; Lanoë, Céline; Lubin, Amélie; Turbelin, Marie-Renée; Rossi, Sandrine; Simon, Grégory; Delcroix, Nicolas; Lamberton, Franck; Vigneau, Mathieu; Wisniewski, Gabriel; Vicet, Jean-René; Mazoyer, Bernard

    2011-11-01

    Jean Piaget's theory is a central reference point in the study of logico-mathematical development in children. One of the most famous Piagetian tasks is number conservation. Failures and successes in this task reveal two fundamental stages in children's thinking and judgment, shifting at approximately 7 years of age from visuospatial intuition to number conservation. In the current study, preschool children (nonconservers, 5-6 years of age) and school-age children (conservers, 9-10 years of age) were presented with Piaget's conservation-of-number task and monitored by functional magnetic resonance imaging (fMRI). The cognitive change allowing children to access conservation was shown to be related to the neural contribution of a bilateral parietofrontal network involved in numerical and executive functions. These fMRI results highlight how the behavioral and cognitive stages Piaget formulated during the 20th century manifest in the brain with age. PMID:21636095

  7. Bipolar programmable current supply for superconducting nuclear magnetic resonance magnets

    NASA Astrophysics Data System (ADS)

    Koivuniemi, Jaakko; Luusalo, Reeta; Hakonen, Pertti

    1998-09-01

    In high resolution continuous-wave nuclear magnetic resonance (NMR) work well-reproducible, linear sweeps of current are needed. We have developed a microcontroller based programmable current supply, tested with superconducting magnets with inductance of 10 mH and 10 H. We achieved a resolution and noise of 4 ppm. The supply has an internal sweep with programmable ramping rate and a possibility for remote operation from a computer with either GPIB or RS232 interface. It is based on an 18-bit D/A converter. The maximum output current is ±10 A, the sweep rate can be set between 1 ?A/s-140 mA/s, and the maximum output voltage is ±2.5 V. In work at ultralow temperatures, especially in superconducting quantum interference device NMR, all rf interference to the experiment should be avoided. One of the sources of this kind of unwanted input is the digital switching noise of fast logic devices. We discuss this problem in the context of our design.

  8. Functional topography of the corpus callosum investigated by DTI and fMRI

    PubMed Central

    Fabri, Mara; Pierpaoli, Chiara; Barbaresi, Paolo; Polonara, Gabriele

    2014-01-01

    This short review examines the most recent functional studies of the topographic organization of the human corpus callosum, the main interhemispheric commissure. After a brief description of its anatomy, development, microstructure, and function, it examines and discusses the latest findings obtained using diffusion tensor imaging (DTI) and tractography (DTT) and functional magnetic resonance imaging (fMRI), three recently developed imaging techniques that have significantly expanded and refined our knowledge of the commissure. While DTI and DTT have been providing insights into its microstructure, integrity and level of myelination, fMRI has been the key technique in documenting the activation of white matter fibers, particularly in the corpus callosum. By combining DTT and fMRI it has been possible to describe the trajectory of the callosal fibers interconnecting the primary olfactory, gustatory, motor, somatic sensory, auditory and visual cortices at sites where the activation elicited by peripheral stimulation was detected by fMRI. These studies have demonstrated the presence of callosal fiber tracts that cross the commissure at the level of the genu, body, and splenium, at sites showing fMRI activation. Altogether such findings lend further support to the notion that the corpus callosum displays a functional topographic organization that can be explored with fMRI. PMID:25550994

  9. The spatiospectral characterization of brain networks: fusing concurrent EEG spectra and fMRI maps

    PubMed Central

    Bridwell, David A.; Wu, Lei; Eichele, Tom; Calhoun, Vince D.

    2013-01-01

    Different imaging modalities capture different aspects of brain activity. Functional Magnetic Resonance Imaging (fMRI) reveals intrinsic networks whose BOLD signals have periods from 100s (0.01 Hz) to about 10s (0.1 Hz). Electroencephalographic (EEG) recordings, in contrast, commonly reflect cortical electrical fluctuations with periods up to 20 ms (50 Hz) or above. We examined the correspondence between intrinsic fMRI and EEG network activity at rest in order to characterize brain networks both spatially (with fMRI) and spectrally (with EEG). Brain networks were separately identified within the concurrently recorded fMRI and EEG at the aggregate group level with group independent component analysis and the association between spatial fMRI and frequency by spatial EEG sources was examined by deconvolving their component time courses. The two modalities are considered linked if the estimated impulse response function (IRF) is significantly non-zero at biologically plausible delays. We found that negative associations were primarily present within two of five alpha components, which highlights the importance of considering multiple alpha sources in EEG-fMRI. Positive associations were primarily present within the lower (e.g. delta and theta) and higher (e.g. upper beta and lower gamma) spectral regions, sometimes within the same fMRI components. Collectively, the results demonstrate a promising approach to characterize brain networks spatially and spectrally, and reveal that positive and negative associations appear within partially distinct regions of the EEG spectrum. PMID:23266744

  10. Microscopic magnetic resonance elastography (?MRE) applications

    NASA Astrophysics Data System (ADS)

    Othman, Shadi F.; Xu, Huihui; Royston, Thomas J.; Magin, Richard L.

    2005-04-01

    Microscopic magnetic resonance elastography (?MRE) is a phase contrast based imaging technique that is capable of mapping the acoustic shear waves resulting from low amplitude cyclic displacement in tissue-like materials. This new technique has proven successful in imaging gel phantoms mimicking soft biological tissues with shear moduli ranging from 0.7 to 40 kPa. The 4-dimensional (4D) spatial-temporal shear wave vector can be measured, which in turn can be used to identify material properties with high spatial resolution. Experiments were conducted using 5 and 10 mm RF saddle coils in the 10 mm vertical imaging bore of an 11.74 Tesla magnet. The field-of-view ranged from 4 to 14 mm, with in plane resolution up to 34 ?m x 34 ?m and slice thickness up to 100 ?m using shear wave excitation of 550 to 580 Hz. In this study, the capability and constraints of ?MRE are investigated. The constraints include the range of measured shear moduli, excitation frequency, and minimum physical sample volume. Applications investigated include: 1) late-stage frog oocytes with typical diameter from 1 to 1.5 mm; and 2) tissue engineered constructs at different growth stages. Mesenchymal stem cells (MSCs) extracted from bone marrow can serve as progenitor cells that differentiate into specific types of tissues such as bone, adipose tissue, cartilage and muscle. ?MRE can monitor the growth of such tissues and evaluate their mechanical properties. Also, a silicon-based tissue phantom material (CF-11-2188, Nusil Technologies) is tested in order to address challenges associated with excitation frequency and the dispersive nature of the media.

  11. Radiofrequency coils for magnetic resonance applications: theory, design, and evaluation.

    PubMed

    Giovannetti, Giulio; Hartwig, Valentina; Positano, Vincenzo; Vanello, Nicola

    2014-01-01

    Magnetic resonance imaging and magnetic resonance spectroscopy are noninvasive diagnostic techniques based on the phenomenon of nuclear magnetic resonance. Radiofrequency coils are key components in both the transmission and receiving phases of magnetic resonance systems. Transmitter coils have to produce a highly homogeneous alternating field in a wide field of view, whereas receiver coils have to maximize signal detection while minimizing noise. Development of modern magnetic resonance coils often is based on numerical methods for simulating and predicting coil performance. Numerical methods allows the behavior of the coil in the presence of realistic loads to be simulated and the coil's efficiency at high magnetic fields to be investigated. After being built, coils have to be characterized in the laboratory to optimize their setting and performance by extracting several quality indices. Successively, coils performance has to be evaluated in a scanner using standardized image quality parameters with phantom and human experiments. This article reviews the principles of radiofrequency coils, coil performance parameters, and their estimation methods using simulations, workbench, and magnetic resonance experiments. Finally, an overview of future developments in radiofrequency coils technology is included. PMID:25403875

  12. Magnetic resonance imaging: present and future applications

    PubMed Central

    Johnston, Donald L.; Liu, Peter; Wismer, Gary L.; Rosen, Bruce R.; Stark, David D.; New, Paul F.J.; Okada, Robert D.; Brady, Thomas J.

    1985-01-01

    Magnetic resonance (MR) imaging has created considerable excitement in the medical community, largely because of its great potential to diagnose and characterize many different disease processes. However, it is becoming increasingly evident that, because MR imaging is similar to computed tomography (CT) scanning in identifying structural disorders and because it is more costly and difficult to use, this highly useful technique must be judged against CT before it can become an accepted investigative tool. At present MR imaging has demonstrated diagnostic superiority over CT in a limited number of important, mostly neurologic, disorders and is complementary to CT in the diagnosis of certain other disorders. For most of the remaining organ systems its usefulness is not clear, but the lack of ionizing radiation and MR's ability to produce images in any tomographic plane may eventually prove to be advantageous. The potential of MR imaging to display in-vivo spectra, multinuclear images and blood-flow data makes it an exciting investigative technique. At present, however, MR imaging units should be installed only in medical centres equipped with the clinical and basic research facilities that are essential to evaluate the ultimate role of this technique in the care of patients. ImagesFig. 5Fig. 6Fig. 7Fig. 8Fig. 9Fig. 10Fig. 11Fig. 12Fig. 13Fig. 14 PMID:3884120

  13. Magnetic resonance imaging of the kidneys

    SciTech Connect

    Leung, A.W.L.; Bydder, G.M.; Steinter, R.E.; Bryant, D.J.; Young, I.R.

    1984-12-01

    A study of the magnetic resonance imaging (MRI) appearance of the kidneys in six normal volunteers and 52 patients is reported. Corticomedullary differentiation was seen with the inversion-recovery (IR 1400/400) sequence in the normal volunteers and in patients with functioning transplanted kidneys and acute tubular necrosis. Partial or total loss of corticomedullary differentiation was seen in glomerulonephritis, acute and chronic renal failure, renal artery stenosis, and transplant rejection. The T1 of the kidneys was increased in glomerulonephritis with neuphrotic syndrome, but the T1 was within the normal range for renal medulla in glomerulonephritis without nephrotic syndrome, renal artery stenosis, and chronic renal failure. A large staghorn calculus was demonstrated with MRI, but small calculi were not seen. Fluid within the hydonephrosis, simple renal cysts, and polycystic kidneys displayed very low signal intensity and long T1 values. Tumors displayed varied appearances. Hypernephromas were shown to be hypo- or hyperintense with the renal medulla on the IR 1400/400 sequence. After intravenous injection of gadolinium-DTPA, there was marked decrease in the tumor T1.

  14. Interventional and intraoperative magnetic resonance imaging.

    PubMed

    Kettenbach, J; Kacher, D F; Koskinen, S K; Silverman, S G; Nabavi, A; Gering, D; Tempany, C M; Schwartz, R B; Kikinis, R; Black, P M; Jolesz, F A

    2000-01-01

    The goal of the Image Guided Therapy Program, as the name implies, is to develop the use of imaging to guide minimally invasive therapy. The program combines interventional and intraoperative magnetic resonance imaging (MRI) with high-performance computing and novel therapeutic devices. In clinical practice the multidisciplinary program provides for the investigation of a wide range of interventional and surgical procedures. The Signa SP 0.5 T superconducting MRI system (GE Medical Systems, Milwaukee, WI) has a 56-cm-wide vertical gap, allowing access to the patient and permitting the execution of interactive MRI-guided procedures. This system is integrated with an optical tracking system and utilizes flexible surface coils and MRI-compatible displays to facilitate procedures. Images are obtained with routine pulse sequences. Nearly real-time imaging, with fast gradient-recalled echo sequences, may be acquired at a rate of one image every 1.5 s with interactive image plane selection. Since 1994, more than 800 of these procedures, including various percutaneous procedures and open surgeries, have been successfully performed at Brigham and Women's Hospital (Boston, MA). PMID:11701527

  15. Magnetic Resonance Imaging of Cartilage Repair

    PubMed Central

    Trattnig, Siegfried; Winalski, Carl S.; Marlovits, Stephan; Jurvelin, Jukka S.; Welsch, Goetz H.; Potter, Hollis G.

    2011-01-01

    Articular cartilage lesions are a common pathology of the knee joint, and many patients may benefit from cartilage repair surgeries that offer the chance to avoid the development of osteoarthritis or delay its progression. Cartilage repair surgery, no matter the technique, requires a noninvasive, standardized, and high-quality longitudinal method to assess the structure of the repair tissue. This goal is best fulfilled by magnetic resonance imaging (MRI). The present article provides an overview of the current state of the art of MRI of cartilage repair. In the first 2 sections, preclinical and clinical MRI of cartilage repair tissue are described with a focus on morphological depiction of cartilage and the use of functional (biochemical) MR methodologies for the visualization of the ultrastructure of cartilage repair. In the third section, a short overview is provided on the regulatory issues of the United States Food and Drug Administration (FDA) and the European Medicines Agency (EMEA) regarding MR follow-up studies of patients after cartilage repair surgeries.

  16. Constraining groundwater modeling with magnetic resonance soundings.

    PubMed

    Boucher, Marie; Favreau, Guillaume; Nazoumou, Yahaya; Cappelaere, Bernard; Massuel, Sylvain; Legchenko, Anatoly

    2012-01-01

    Magnetic resonance sounding (MRS) is a noninvasive geophysical method that allows estimating the free water content and transmissivity of aquifers. In this article, the ability of MRS to improve the reliability of a numerical groundwater model is assessed. Thirty-five sites were investigated by MRS over a ?5000 km(2) domain of the sedimentary Continental Terminal aquifer in SW Niger. Time domain electromagnetic soundings were jointly carried out to estimate the aquifer thickness. A groundwater model was previously built for this section of the aquifer and forced by the outputs from a distributed surface hydrology model, to simulate the observed long-term (1992 to 2003) rise in the water table. Uncertainty analysis had shown that independent estimates of the free water content and transmissivity values of the aquifer would facilitate cross-evaluation of the surface-water and groundwater models. MRS results indicate ranges for permeability (K = 1 × 10(-5) to 3 × 10(-4) m/s) and for free water content (w = 5% to 23% m(3) /m(3) ) narrowed by two orders of magnitude (K) and by ?50% (w), respectively, compared to the ranges of permeability and specific yield values previously considered. These shorter parameter ranges result in a reduction in the model's equifinality (whereby multiple combinations of model's parameters are able to represent the same observed piezometric levels), allowing a better constrained estimate to be derived for net aquifer recharge (?22 mm/year). PMID:22150349

  17. Magnetic Resonance Imaging of the Living Brain

    PubMed Central

    Rosenbloom, Margaret J.; Pfefferbaum, Adolf

    2008-01-01

    Magnetic resonance imaging (MRI) provides a safe, noninvasive method to examine the brain’s macrostructure, microstructure, and some aspects of how the living brain functions. MRI is capable of detecting abnormalities that can occur with alcoholism as well as changes that can occur with sobriety and relapse. The brain pathology associated with chronic excessive alcohol consumption is well documented with imaging of the living body (i.e., in vivo imaging). Consistent findings include shrinkage of the frontal cortex,1 underlying white matter, and cerebellum and expansion of the ventricles. Some of these changes are reversible with abstinence, but some appear to be enduring. Research showing correlations between brain structure and quantitative neuropsychological testing demonstrates the functional consequences of the pathology. In addition, functional imaging studies provide evidence that the brain compensates for cognitive deficits. The myriad concomitants of alcoholism, the antecedents, and the consumption patterns each may influence the observed brain changes associated with alcoholism, which tend to be more deleterious with increasing age. The multifaceted nature of alcoholism presents unique challenges and opportunities to understand the mechanisms underlying alcoholism-induced neuropathology and its recovery. Longitudinal MRI studies of animal models of alcoholism, however, can address questions about the development and course of alcohol dependence and the scope and limits of in vivo degeneration and recovery of brain structure and concomitant function that may not be readily addressed in clinical studies. PMID:23584010

  18. Magnetic Resonance Image Example Based Contrast Synthesis

    PubMed Central

    Roy, Snehashis; Carass, Aaron; Prince, Jerry L.

    2013-01-01

    The performance of image analysis algorithms applied to magnetic resonance images is strongly influenced by the pulse sequences used to acquire the images. Algorithms are typically optimized for a targeted tissue contrast obtained from a particular implementation of a pulse sequence on a specific scanner. There are many practical situations, including multi-institution trials, rapid emergency scans, and scientific use of historical data, where the images are not acquired according to an optimal protocol or the desired tissue contrast is entirely missing. This paper introduces an image restoration technique that recovers images with both the desired tissue contrast and a normalized intensity profile. This is done using patches in the acquired images and an atlas containing patches of the acquired and desired tissue contrasts. The method is an example-based approach relying on sparse reconstruction from image patches. Its performance in demonstrated using several examples, including image intensity normalization, missing tissue contrast recovery, automatic segmentation, and multimodal registration. These examples demonstrate potential practical uses and also illustrate limitations of our approach. PMID:24058022

  19. INVITED TOPICAL REVIEW: Parallel magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Larkman, David J.; Nunes, Rita G.

    2007-04-01

    Parallel imaging has been the single biggest innovation in magnetic resonance imaging in the last decade. The use of multiple receiver coils to augment the time consuming Fourier encoding has reduced acquisition times significantly. This increase in speed comes at a time when other approaches to acquisition time reduction were reaching engineering and human limits. A brief summary of spatial encoding in MRI is followed by an introduction to the problem parallel imaging is designed to solve. There are a large number of parallel reconstruction algorithms; this article reviews a cross-section, SENSE, SMASH, g-SMASH and GRAPPA, selected to demonstrate the different approaches. Theoretical (the g-factor) and practical (coil design) limits to acquisition speed are reviewed. The practical implementation of parallel imaging is also discussed, in particular coil calibration. How to recognize potential failure modes and their associated artefacts are shown. Well-established applications including angiography, cardiac imaging and applications using echo planar imaging are reviewed and we discuss what makes a good application for parallel imaging. Finally, active research areas where parallel imaging is being used to improve data quality by repairing artefacted images are also reviewed.

  20. TOPICAL REVIEW: Endovascular interventional magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Bartels, L. W.; Bakker, C. J. G.

    2003-07-01

    Minimally invasive interventional radiological procedures, such as balloon angioplasty, stent placement or coiling of aneurysms, play an increasingly important role in the treatment of patients suffering from vascular disease. The non-destructive nature of magnetic resonance imaging (MRI), its ability to combine the acquisition of high quality anatomical images and functional information, such as blood flow velocities, perfusion and diffusion, together with its inherent three dimensionality and tomographic imaging capacities, have been advocated as advantages of using the MRI technique for guidance of endovascular radiological interventions. Within this light, endovascular interventional MRI has emerged as an interesting and promising new branch of interventional radiology. In this review article, the authors will give an overview of the most important issues related to this field. In this context, we will focus on the prerequisites for endovascular interventional MRI to come to maturity. In particular, the various approaches for device tracking that were proposed will be discussed and categorized. Furthermore, dedicated MRI systems, safety and compatibility issues and promising applications that could become clinical practice in the future will be discussed.

  1. Haptic fMRI: combining functional neuroimaging with haptics for studying the brain's motor control representation.

    PubMed

    Menon, Samir; Brantner, Gerald; Aholt, Chris; Kay, Kendrick; Khatib, Oussama

    2013-01-01

    A challenging problem in motor control neuroimaging studies is the inability to perform complex human motor tasks given the Magnetic Resonance Imaging (MRI) scanner's disruptive magnetic fields and confined workspace. In this paper, we propose a novel experimental platform that combines Functional MRI (fMRI) neuroimaging, haptic virtual simulation environments, and an fMRI-compatible haptic device for real-time haptic interaction across the scanner workspace (above torso ? .65×.40×.20m(3)). We implement this Haptic fMRI platform with a novel haptic device, the Haptic fMRI Interface (HFI), and demonstrate its suitability for motor neuroimaging studies. HFI has three degrees-of-freedom (DOF), uses electromagnetic motors to enable high-fidelity haptic rendering (>350Hz), integrates radio frequency (RF) shields to prevent electromagnetic interference with fMRI (temporal SNR >100), and is kinematically designed to minimize currents induced by the MRI scanner's magnetic field during motor displacement (<2cm). HFI possesses uniform inertial and force transmission properties across the workspace, and has low friction (.05-.30N). HFI's RF noise levels, in addition, are within a 3 Tesla fMRI scanner's baseline noise variation (?.85±.1%). Finally, HFI is haptically transparent and does not interfere with human motor tasks (tested for .4m reaches). By allowing fMRI experiments involving complex three-dimensional manipulation with haptic interaction, Haptic fMRI enables-for the first time-non-invasive neuroscience experiments involving interactive motor tasks, object manipulation, tactile perception, and visuo-motor integration. PMID:24110643

  2. Broadband electrically detected magnetic resonance using adiabatic pulses.

    PubMed

    Hrubesch, F M; Braunbeck, G; Voss, A; Stutzmann, M; Brandt, M S

    2015-05-01

    We present a broadband microwave setup for electrically detected magnetic resonance (EDMR) based on microwave antennae with the ability to apply arbitrarily shaped pulses for the excitation of electron spin resonance (ESR) and nuclear magnetic resonance (NMR) of spin ensembles. This setup uses non-resonant stripline structures for on-chip microwave delivery and is demonstrated to work in the frequency range from 4MHz to 18GHz. ? pulse times of 50ns and 70?s for ESR and NMR transitions, respectively, are achieved with as little as 100mW of microwave or radiofrequency power. The use of adiabatic pulses fully compensates for the microwave magnetic field inhomogeneity of the stripline antennae, as demonstrated with the help of BIR4 unitary rotation pulses driving the ESR transition of neutral phosphorus donors in silicon and the NMR transitions of ionized phosphorus donors as detected by electron nuclear double resonance (ENDOR). PMID:25828243

  3. Broadband electrically detected magnetic resonance using adiabatic pulses

    NASA Astrophysics Data System (ADS)

    Hrubesch, F. M.; Braunbeck, G.; Voss, A.; Stutzmann, M.; Brandt, M. S.

    2015-05-01

    We present a broadband microwave setup for electrically detected magnetic resonance (EDMR) based on microwave antennae with the ability to apply arbitrarily shaped pulses for the excitation of electron spin resonance (ESR) and nuclear magnetic resonance (NMR) of spin ensembles. This setup uses non-resonant stripline structures for on-chip microwave delivery and is demonstrated to work in the frequency range from 4 MHz to 18 GHz. ? pulse times of 50 ns and 70 ?s for ESR and NMR transitions, respectively, are achieved with as little as 100 mW of microwave or radiofrequency power. The use of adiabatic pulses fully compensates for the microwave magnetic field inhomogeneity of the stripline antennae, as demonstrated with the help of BIR4 unitary rotation pulses driving the ESR transition of neutral phosphorus donors in silicon and the NMR transitions of ionized phosphorus donors as detected by electron nuclear double resonance (ENDOR).

  4. Design algorithms for parallel transmission in magnetic resonance imaging

    E-print Network

    Setsompop, Kawin

    2008-01-01

    The focus of this dissertation is on the algorithm design, implementation, and validation of parallel transmission technology in Magnetic Resonance Imaging (MRI). Novel algorithms are proposed which yield excellent excitation ...

  5. Improvements in magnetic resonance imaging excitation pulse design

    E-print Network

    Zelinski, Adam Charles

    2008-01-01

    This thesis focuses on the design of magnetic resonance imaging (MRI) radio-frequency (RF) excitation pulses, and its primary contributions are made through connections with the novel multiple-system single-output (MSSO) ...

  6. Model-based reconstruction of magnetic resonance spectroscopic imaging

    E-print Network

    Chatnuntawech, Itthi

    2013-01-01

    Magnetic resonance imaging (MRI) is a medical imaging technique that is used to obtain images of soft tissue throughout the body. Since its development in the 1970s, MRI has gained tremendous importance in clinical practice ...

  7. Single-scan multidimensional magnetic resonance Assaf Tal, Lucio Frydman *

    E-print Network

    Frydman, Lucio

    Single-scan multidimensional magnetic resonance Assaf Tal, Lucio Frydman * The Department . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242 1.1. Spatial encoding and single-scan 2D NMR spectroscopy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249 3. Single-scan ultrafast 2D NMR

  8. Microfluidically Cryo-Cooled Planar Coils for Magnetic Resonance Imaging

    E-print Network

    Koo, Chiwan

    2013-08-09

    High signal-to-noise ratio (SNR) is typically required for higher resolution and faster speed in magnetic resonance imaging (MRI). Planar microcoils as receiver probes in MRI systems offer the potential to be configured into array elements for fast...

  9. Nuclear magnetic resonance data of CF3I

    NASA Astrophysics Data System (ADS)

    Kalinowski, H.-O.; Kumar, M.; Gupta, V.; Gupta, R.

    This document is part of Part 1 `Aliphatic Compounds' of Subvolume D 'Chemical Shifts and Coupling Constants for Carbon-13' of Landolt-Börnstein III/35 'Nuclear Magnetic Resonance Data', Group III 'Condensed Matter'.

  10. An investigation of receiver probe development for magnetic resonance microscopy 

    E-print Network

    Boyer, Jeffrey Scott

    1995-01-01

    Much research in Magnetic Resonance Imaging has been directed toward the development of new hardware systems that can obtain high resolution images, typically on the order of tens of microns, for small field-of-views, ...

  11. Target-specific contrast agents for magnetic resonance microscopy

    E-print Network

    Hepler Blackwell, Megan Leticia

    2007-01-01

    High-resolution ex vivo magnetic resonance microscopy (MRM) can be used to delineate prominent architectonic features in the human brain, but increased contrast is required to visualize more subtle distinctions. The goal ...

  12. Detection of brain metabolites in magnetic resonance spectroscopy

    E-print Network

    Kok, Trina

    2009-01-01

    While magnetic resonance imaging (MRI) derives its signal from protons in water, additional and potentially important biochemical compounds are detectable in vivo within the proton spectrum. The detection and mapping of ...

  13. Magnetic resonance imaging contrast agents for chemical sensing

    E-print Network

    Liu, Vincent Hok

    2014-01-01

    Magnetic resonance imaging (MRI) is frequently used for examining the human body. MRI contrast agents currently used in the clinic assist physicians in locating problematic areas, but other tools are needed to interrogate ...

  14. Diagnosis of hematogenous pyogenic vertebral osteomyelitis by magnetic resonance imaging

    SciTech Connect

    Meyers, S.P.; Wiener, S.N. (Mt Sinai Medical Center, Cleveland, OH (USA))

    1991-04-01

    The clinical information and imaging data from 27 patients with hematogenous pyogenic vertebral osteomyelitis were reviewed. All patients had roentgenographic and magnetic resonance imaging examinations. Seventeen patients had computed tomograms; 17 had technetium Tc 99m medronate bone scans; and seven had gallium citrate Ga 67 scans. Magnetic resonance imaging, when used as a part of the initial radiologic evaluation, detected abnormalities consistent with osteomyelitis in all 27 patients. Magnetic resonance imaging also demonstrated paravertebral and/or epidural extension of infection in 14 patients, including seven patients who had neurologic signs of lower-extremity weakness. Roentgenograms, computed tomograms, technetium bone scans, and gallium scans had findings suggestive of the diagnosis in 48%, 65%, 71%, and 86% of the patients, respectively. We recommend magnetic resonance imaging as an important and perhaps critical imaging modality for detection of pyogenic vertebral osteomyelitis.

  15. Imaging agents for in vivo magnetic resonance and scintigraphic imaging

    DOEpatents

    Engelstad, Barry L. (Orinda, CA); Raymond, Kenneth N. (Berkeley, CA); Huberty, John P. (Corte Madera, CA); White, David L. (Oakland, CA)

    1991-01-01

    Methods are provided for in vivo magnetic resonance imaging and/or scintigraphic imaging of a subject using chelated transition metal and lanthanide metal complexes. Novel ligands for these complexes are provided.

  16. Designing and characterizing hyperpolarizable silicon nanoparticles for magnetic resonance imaging

    E-print Network

    Anahtar, Melis Nuray

    2008-01-01

    Magnetic Resonance Imaging (MRI) is one of the most powerful noninvasive tools for diagnosing human disease, but its utility is limited because current contrast agents are ineffective when imaging air-tissue interfaces, ...

  17. Imaging agents for in vivo magnetic resonance and scintigraphic imaging

    DOEpatents

    Engelstad, B.L.; Raymond, K.N.; Huberty, J.P.; White, D.L.

    1991-04-23

    Methods are provided for in vivo magnetic resonance imaging and/or scintigraphic imaging of a subject using chelated transition metal and lanthanide metal complexes. Novel ligands for these complexes are provided. No Drawings

  18. Assessment of coronary artery stenosis by magnetic resonance imaging.

    PubMed Central

    Pennell, D. J.; Bogren, H. G.; Keegan, J.; Firmin, D. N.; Underwood, S. R.

    1996-01-01

    OBJECTIVE: The findings of magnetic resonance and x-ray angiography were compared for assessment of coronary artery stenosis in this validation study. BACKGROUND: Magnetic resonance angiography of the coronary arteries has recently been described, but there has been no comparison with x-ray angiography of localisation or assessment of important characteristics of coronary stenosis. METHODS: A breath hold, segmented k-space, 2D gradient echo imaging technique incorporating fat suppression was used in 39 patients (55 coronary stenoses) with known coronary artery disease. RESULTS: Overall, 47 stenoses (85%) were assessed by magnetic resonance (29 of 33 stenoses in the left anterior descending artery, one of one in the left main stem, 14 of 17 in the right coronary artery, and three of four in the left circumflex artery were detected). There was close agreement between magnetic resonance and x-ray angiography for the distance of the stenosis from the arterial origin (magnetic resonance mean (SD) 27 (16) mm versus x-ray angiography 27 (16) mm, P = NS, mean difference -0.2 mm). The distance to 39 stenoses (83%) agreed to within 5 mm, with increased scatter for more distal stenoses. The severity of magnetic resonance signal loss, assessed visually at the site of stenosis, varied significantly according to the percentage diameter stenosis (F = 30, P < 0.0001); stenosis severity with severe signal loss was 89 (7)%, with partial signal was 70 (16)%, and with irregular wall only 37 (11)%, with significant differences among the three groups (P < 0.001). A significant correlation was found between the proportional magnetic resonance signal loss at the stenosis and the percentage diameter stenosis severity (r = -0.67, P < 0.0001). The length of stenosis measured by magnetic resonance (6 (3) mm) was greater than by x-ray angiography (5 (2) mm, P < 0.006, mean difference +1.1 mm). Spearman's rank test showed that there was significant overestimation of stenosis length by magnetic resonance as stenosis severity increased (rs = 0.34, P < 0.02). CONCLUSIONS: Accurate localisation of coronary stenosis and a qualitative assessment of stenosis severity are possible by magnetic resonance, but stenosis length is overestimated as severity increases, probably because of disturbed patterns of flow with turbulence distal to severe stenoses. Reasonable results for the detection of coronary artery stenosis by magnetic resonance were achieved in this highly selected population, but further progress in imaging techniques is necessary before moving towards appreciable clinical application. Images PMID:8673749

  19. Multivoxel Pattern Analysis for fMRI Data: A Review

    PubMed Central

    Takerkart, Sylvain; Regragui, Fakhita; Boussaoud, Driss; Brovelli, Andrea

    2012-01-01

    Functional magnetic resonance imaging (fMRI) exploits blood-oxygen-level-dependent (BOLD) contrasts to map neural activity associated with a variety of brain functions including sensory processing, motor control, and cognitive and emotional functions. The general linear model (GLM) approach is used to reveal task-related brain areas by searching for linear correlations between the fMRI time course and a reference model. One of the limitations of the GLM approach is the assumption that the covariance across neighbouring voxels is not informative about the cognitive function under examination. Multivoxel pattern analysis (MVPA) represents a promising technique that is currently exploited to investigate the information contained in distributed patterns of neural activity to infer the functional role of brain areas and networks. MVPA is considered as a supervised classification problem where a classifier attempts to capture the relationships between spatial pattern of fMRI activity and experimental conditions. In this paper , we review MVPA and describe the mathematical basis of the classification algorithms used for decoding fMRI signals, such as support vector machines (SVMs). In addition, we describe the workflow of processing steps required for MVPA such as feature selection, dimensionality reduction, cross-validation, and classifier performance estimation based on receiver operating characteristic (ROC) curves. PMID:23401720

  20. fMRI analysis software tools: an evaluation framework

    NASA Astrophysics Data System (ADS)

    Pedoia, Valentina; Colli, Vittoria; Strocchi, Sabina; Vite, Cristina; Binaghi, Elisabetta; Conte, Leopoldo

    2011-03-01

    Performance comparison of functional Magnetic Resonance Imaging (fMRI) software tools is a very difficult task. In this paper, a framework for comparison of fMRI analysis results obtained with different software packages is proposed. An objective evaluation is possible only after pre-processing steps that normalize input data in a standard domain. Segmentation and registration algorithms are implemented in order to classify voxels belonging to brain or not, and to find the non rigid transformation that best aligns the volume under inspection with a standard one. Through the definitions of intersection and union of fuzzy logic an index was defined which quantify information overlap between Statistical Parametrical Maps (SPMs). Direct comparison between fMRI results can only highlight differences. In order to assess the best result, an index that represents the goodness of the activation detection is required. The transformation of the activation map in a standard domain allows the use of a functional Atlas for labeling the active voxels. For each functional area the Activation Weighted Index (AWI) that identifies the mean activation level of whole area was defined. By means of this brief, but comprehensive description, it is easy to find a metric for the objective evaluation of a fMRI analysis tools. Trough the first evaluation method the situations where the SPMs are inconsistent were identified. The result of AWI analysis suggest which tool has higher sensitivity and specificity. The proposed method seems a valid evaluation tool when applied to an adequate number of patients.

  1. An electrophysiological validation of stochastic DCM for fMRI

    PubMed Central

    Daunizeau, J.; Lemieux, L.; Vaudano, A. E.; Friston, K. J.; Stephan, K. E.

    2013-01-01

    In this note, we assess the predictive validity of stochastic dynamic causal modeling (sDCM) of functional magnetic resonance imaging (fMRI) data, in terms of its ability to explain changes in the frequency spectrum of concurrently acquired electroencephalography (EEG) signal. We first revisit the heuristic model proposed in Kilner et al. (2005), which suggests that fMRI activation is associated with a frequency modulation of the EEG signal (rather than an amplitude modulation within frequency bands). We propose a quantitative derivation of the underlying idea, based upon a neural field formulation of cortical activity. In brief, dense lateral connections induce a separation of time scales, whereby fast (and high spatial frequency) modes are enslaved by slow (low spatial frequency) modes. This slaving effect is such that the frequency spectrum of fast modes (which dominate EEG signals) is controlled by the amplitude of slow modes (which dominate fMRI signals). We then use conjoint empirical EEG-fMRI data—acquired in epilepsy patients—to demonstrate the electrophysiological underpinning of neural fluctuations inferred from sDCM for fMRI. PMID:23346055

  2. An electrophysiological validation of stochastic DCM for fMRI.

    PubMed

    Daunizeau, J; Lemieux, L; Vaudano, A E; Friston, K J; Stephan, K E

    2012-01-01

    In this note, we assess the predictive validity of stochastic dynamic causal modeling (sDCM) of functional magnetic resonance imaging (fMRI) data, in terms of its ability to explain changes in the frequency spectrum of concurrently acquired electroencephalography (EEG) signal. We first revisit the heuristic model proposed in Kilner et al. (2005), which suggests that fMRI activation is associated with a frequency modulation of the EEG signal (rather than an amplitude modulation within frequency bands). We propose a quantitative derivation of the underlying idea, based upon a neural field formulation of cortical activity. In brief, dense lateral connections induce a separation of time scales, whereby fast (and high spatial frequency) modes are enslaved by slow (low spatial frequency) modes. This slaving effect is such that the frequency spectrum of fast modes (which dominate EEG signals) is controlled by the amplitude of slow modes (which dominate fMRI signals). We then use conjoint empirical EEG-fMRI data-acquired in epilepsy patients-to demonstrate the electrophysiological underpinning of neural fluctuations inferred from sDCM for fMRI. PMID:23346055

  3. Assessment of coronary artery stenosis by magnetic resonance imaging

    Microsoft Academic Search

    D. J. Pennell; H. G. Bogren; J. Keegan; D. N. Firmin; S. R. Underwood

    1996-01-01

    OBJECTIVE: The findings of magnetic resonance and x-ray angiography were compared for assessment of coronary artery stenosis in this validation study. BACKGROUND: Magnetic resonance angiography of the coronary arteries has recently been described, but there has been no comparison with x-ray angiography of localisation or assessment of important characteristics of coronary stenosis. METHODS: A breath hold, segmented k-space, 2D gradient

  4. Towards magnetic resonance imaging guided radiation therapy (MRIgRT)

    Microsoft Academic Search

    Teodor Marius Stanescu

    2008-01-01

    The goal of this work is to address key aspects of the magnetic resonance imaging guided radiation therapy (MRIgRT) process of cancer sites. MRIgRT is implemented by using a system comprised of a magnetic resonance imaging (MRI) scanner coupled with a radiation source, in our case a radiotherapy accelerator (Linac). The potential benefits of MRIgRT are the real-time tracking of

  5. Cost effectiveness of magnetic resonance imaging in the neurosciences.

    PubMed Central

    Szczepura, A K; Fletcher, J; Fitz-Patrick, J D

    1991-01-01

    OBJECTIVES--To measure, in a service setting, the effect of magnetic resonance imaging on diagnosis, diagnostic certainty, and patient management in the neurosciences; to measure the cost per patient scanned; to estimate the marginal cost of imaging and compare this with its diagnostic impact; to measure changes in patients' quality of life; and to record the diagnostic pathway leading to magnetic resonance imaging. DESIGN--Controlled observational study using questionnaires on diagnosis and patient management before and after imaging. Detailed costing study. Quality of life questionnaires at the time of imaging and six months later. Diagnostic pathways extracted from medical records for a representative sample. SETTING--Regional superconducting 1.5 T magnetic resonance service. SUBJECTS--782 consecutive neuroscience patients referred by consultants for magnetic resonance imaging during June 1988-9; diagnostic pathways recorded for 158 cases. MAIN OUTCOME MEASURES--Costs of magnetic resonance imaging and preliminary investigations; changes in planned management and resulting savings; changes in principal diagnosis and diagnostic certainty; changes in patients' quality of life. RESULTS--Average cost of magnetic resonance imaging was estimated at 206.20/patient pounds (throughput 2250 patients/year, 1989-90 prices including contrast and upgrading). Before magnetic resonance imaging diagnostic procedures cost 164.40/patient pounds (including inpatient stays). Management changed after imaging in 208 (27%) cases; saving an estimated 80.90/patient pounds. Confidence in planned management increased in a further 226 (29%) referrals. Consultants' principal diagnosis changed in 159 of 782 (20%) referrals; marginal cost per diagnostic change was 626 pounds. Confidence in diagnosis increased in 236 (30%) referrals. No improvement in patients' quality of life at six month assessment. CONCLUSIONS--Any improvement in diagnosis with magnetic resonance imaging is achieved at a higher cost. Techniques for monitoring the cost effectiveness of this technology need to be developed. PMID:1819260

  6. Magnetic resonance imaging appearance of hypertensive encephalopathy in a dog.

    PubMed

    Bowman, Chloe A; Witham, Adrian; Tyrrell, Dayle; Long, Sam N

    2015-01-01

    A 16-year-old female spayed English Staffordshire terrier was presented for evaluation of a 10-month history of intermittent myoclonic episodes, and a one weeks history of short episodes of altered mentation, ataxia and collapse. Magnetic resonance imaging identified subcortical oedema, predominately in the parietal and temporal lobes and multiple cerebral microbleeds. Serum biochemistry, indirect blood pressure measurements and magnetic resonance imaging abnormalities were consistent with hypertensive encephalopathy secondary to chronic kidney disease. PMID:25949801

  7. Equivalent Magnetization Current Method Applied to the Design of Gradient Coils for Magnetic Resonance Imaging

    Microsoft Academic Search

    Hector Sanchez Lopez; Feng Liu; Michael Poole; Stuart Crozier

    2009-01-01

    A new method is described for the design of gradient coils for magnetic resonance imaging systems. The method is based on the known equivalence between a magnetized volume surrounded by a conducting surface and its equivalent representation by a surface current density. The curl of a vertical magnetization vector of a magnetized thin volume is equivalent to a surface current

  8. Magnetic characterization of austenitic stainless steel for nuclear magnetic resonance coils

    Microsoft Academic Search

    C. A. Swenson; W. D. Markiewicz

    2000-01-01

    Magnetic field uniformity is critical to nuclear magnetic resonance (NMR). Ferromagnetic materials can cause field inhomogeneity. Historically magnet constructions have avoided ferrous alloys to minimize field distortions. This strategy becomes problematic when fabricating large high field magnets because austenitic stainless steel is the preferred and necessary material for bore tubes and winding reinforcement in Nb3Sn coils. The selection of a

  9. Ferromagnetic resonance of a magnetic dimer with dipolar coupling

    NASA Astrophysics Data System (ADS)

    Franco, A. F.; Déjardin, J. L.; Kachkachi, H.

    2014-12-01

    We develop a general formalism for analyzing the ferromagnetic resonance characteristics of a magnetic dimer consisting of two magnetic elements (in a horizontal or vertical configuration) coupled by dipolar interaction, taking account of their finite-size and aspect ratio. We study the effect on the resonance frequency and resonance field of the applied magnetic field (in amplitude and direction), the inter-element coupling, and the (uniaxial) anisotropy in various configurations. We obtain analytical expressions for the resonance frequency in various regimes of the interlayer coupling. We (numerically) investigate the behavior of the resonance field in the corresponding regimes. The critical value of the applied magnetic field at which the resonance frequency vanishes may be an increasing or a decreasing function of the dimer's coupling, depending on the anisotropy configuration. It is also a function of the nanomagnets aspect ratio in the case of in-plane anisotropy. This and several other results of this work, when compared with experiments using the standard ferromagnetic resonance with fixed frequency, or the network analyzer with varying frequency and applied magnetic field, provide a useful means for characterizing the effective anisotropy and coupling within systems of stacked or assembled nanomagnets. Comparing with the experimental data for the frequency splitting of coupled FeV nano disks, we find that our theory provides the same order of magnitude for the dipolar coupling.

  10. Optical Detection of Nuclear Magnetic Resonance in Paramagnetic Ions

    Microsoft Academic Search

    C. W. Thiel

    Methods of optically detecting nuclear magnetic resonance in materials that contain paramagnetic ions exhibiting electronic transitions in the visible or near-visible region of the spectrum are discussed with particular emphasis on the application to the study of crystalline insulators that contain dilute quantities of rare-earth ions. Experimental and theoretical aspects of spectral holeburning techniques (ODNMR), nuclear double resonance methods (PENDOR),

  11. Anisotropy Dispersion and Ferromagnetic Resonance of Amorphous Soft Magnetic Films

    Microsoft Academic Search

    M. Jimbo; S. Tsunashima; S. Uchiyama

    1991-01-01

    Measurement of the anisotropy dispersion using ferromagnetic resonance at radio frequencies has been reconsidered, taking into account the skin effect in relatively thick soft magnetic films. Numerical calculations for 1 ¿m thick amorphous films showed that eddy current losses are comparable to the resonance absorption. The measured absorption for CoZr film is larger than the calculated absorption under a low

  12. Specificity of stimulus-evoked fMRI responses in the mouse: the influence of systemic physiological changes associated with innocuous stimulation under four different anesthetics.

    PubMed

    Schroeter, Aileen; Schlegel, Felix; Seuwen, Aline; Grandjean, Joanes; Rudin, Markus

    2014-07-01

    Functional magnetic resonance (fMRI) in mice has become an attractive tool for mechanistic studies, for characterizing models of human disease, and for evaluation of novel therapies. Yet, controlling the physiological state of mice is challenging, but nevertheless important as changes in cardiovascular parameters might affect the hemodynamic readout which constitutes the basics of the fMRI signal. In contrast to rats, fMRI studies in mice report less robust brain activation of rather widespread character to innocuous sensory stimulation. Anesthesia is known to influence the characteristics of the fMRI signal. To evaluate modulatory effects imposed by the anesthesia on stimulus-evoked fMRI responses, we compared blood oxygenation level dependent (BOLD) and cerebral blood volume (CBV) signal changes to electrical hindpaw stimulation using the four commonly used anesthetics isoflurane, medetomidine, propofol and urethane. fMRI measurements were complemented by assessing systemic physiological parameters throughout the experiment. Unilateral stimulation of the hindpaw elicited widespread fMRI responses in the mouse brain displaying a bilateral pattern irrespective of the anesthetic used. Analysis of magnitude and temporal profile of BOLD and CBV signals indicated anesthesia-specific modulation of cerebral hemodynamic responses and differences observed for the four anesthetics could be largely explained by their known effects on animal physiology. Strikingly, independent of the anesthetic used our results reveal that fMRI responses are influenced by stimulus-induced cardiovascular changes, which indicate an arousal response, even to innocuous stimulation. This may mask specific fMRI signal associated to the stimulus. Hence, studying the processing of peripheral input in mice using fMRI techniques constitutes a major challenge and adapted paradigms and/or alternative fMRI readouts should also be considered when studying sensory processing in mice. PMID:24495809

  13. Single Molecule Magnetic Force Detection with a Carbon Nanotube Resonator

    NASA Astrophysics Data System (ADS)

    Willick, Kyle; Walker, Sean; Baugh, Jonathan

    2015-03-01

    Single molecule magnets (SMMs) sit at the boundary between macroscopic magnetic behaviour and quantum phenomena. Detecting the magnetic moment of an individual SMM would allow exploration of this boundary, and could enable technological applications based on SMMs such as quantum information processing. Detection of these magnetic moments remains an experimental challenge, particularly at the time scales of relaxation and decoherence. We present a technique for sensitive magnetic force detection that should permit such measurements. A suspended carbon nanotube (CNT) mechanical resonator is combined with a magnetic field gradient generated by a ferromagnetic gate electrode, which couples the magnetic moment of a nanomagnet to the resonant motion of the CNT. Numerical calculations of the mechanical resonance show that resonant frequency shifts on the order of a few kHz arise due to single Bohr magneton changes in magnetic moment. A signal-to-noise analysis based on thermomechanical noise shows that magnetic switching at the level of a Bohr magneton can be measured in a single shot on timescales as short as 10 ?s. This sensitivity should enable studies of the spin dynamics of an isolated SMM, within the spin relaxation timescales for many available SMMs. Supported by NSERC.

  14. Properties of a novel magnetized alginate for magnetic resonance imaging.

    PubMed

    Shen, Feng; Poncet-Legrand, Celine; Somers, Sat; Slade, Andrea; Yip, Christopher; Duft, Andy M; Winnik, Françoise M; Chang, Patricia L

    2003-08-01

    Implanting recombinant cells encapsulated in alginate microcapsules to secrete therapeutic proteins has been proven clinically effective in treating several murine models of human diseases. However, once implanted, these microcapsules cannot be assessed without invasive surgery. We now report the preparation and characterization of a novel ferrofluid to render these microcapsules visible with magnetic resonance imaging (MRI). The ferrofluid was prepared as a colloidal iron oxide stabilized in water by alginate. The presence of iron particles in the ferrofluid was verified with chemical titration, dynamic light scattering, and magnetization measurement. The microcapsules fabricated with various concentrations of the ferrofluid in the core, or on the surface of alginate microcapsules, or both, all produced microcapsules with smooth surfaces as shown with light and scanning electron microscopy. However, at the nanoscale level, as revealed with atomic force microscopy, the ferrofluid-fabricated microcapsules demonstrated increased granularity, particularly when the ferrofluid was used to laminate the surface. From the force spectroscopy measurements, these modified microcapsules showed increasing surface rigidity in the following order: traditional alginate < ferrofluid in the core < ferrofluid on the surface. Although the mechanical stability of low-concentration ferrofluid (0.1%) microcapsules was reduced, increasing concentrations, up to 20%, were able to improve stability. When these ferrofluid microcapsules were examined with MRI, their T(2) relaxation time was reduced, thereby producing increased contrast readily detectable with MRI, whereas the traditional alginate microcapsules showed no difference when compared with water. In conclusion, such ferrofluid-enhanced alginate is suitable for fabricating microcapsules that offer the potential for in vivo tracking of implanted microcapsules without invasive surgery. PMID:12783484

  15. Functional investigations of exercising muscle: a noninvasive magnetic resonance spectroscopy-magnetic resonance imaging approach.

    PubMed

    Bendahan, D; Giannesini, B; Cozzone, P J

    2004-05-01

    Muscle fatigue, which is defined as the decline in muscle performance during exercise, may occur at different sites along the pathway from the central nervous system through to the intramuscular contractile machinery. Historically, both impairment of neuromuscular transmission and peripheral alterations within the muscle have been proposed as causative factors of fatigue development. However, according to more recent studies, muscle energetics play a key role in this process. Intramyoplasmic accumulation of inorganic phosphate (P(i)) and limitation in ATP availability have been frequently evoked as the main mechanisms leading to fatigue. Although attractive, these hypotheses have been elaborated on the basis of experimental results obtained in vitro, and their physiological relevance has never been clearly demonstrated in vivo. In that context, noninvasive methods such as 31-phosphorus magnetic resonance spectroscopy and surface electromyography have been employed to understand both metabolic and electrical aspects of muscle fatigue under physiological conditions. Mapping of muscles activated during exercise is another interesting issue which can be addressed using magnetic resonance imaging (MRI). Exercise-induced T2 changes have been used in order to locate activated muscles and also as a quantitative index of exercise intensity. The main results related to both issues, i.e. the metabolic and electrical aspects of fatigue and the MRI functional investigation of exercising muscle, are discussed in the present review. PMID:15112049

  16. Lateralized Tinnitus Studied With Functional Magnetic Resonance Imaging: Abnormal Inferior Colliculus Activation

    Microsoft Academic Search

    J. R. MELCHER; I. S. SIGALOVSKY; J. J. GUINAN; R. A. LEVINE

    2000-01-01

    This paper presents an approach for using functionalmagnetic resonance imaging (fMRI) to investigate the physiology oftinnitus and demonstrates that the approach is effective in revealingtinnitus-related abnormalities in brain function. Our approach as appliedhere included 1) using a masking noise stimulus to change tinnitusloudness and examining the inferior colliculus (IC) for correspondingchanges in activity, 2) separately considering subpopulations with particulartinnitus...

  17. High-throughput optogenetic functional magnetic resonance imaging with parallel computations

    PubMed Central

    Fang, Zhongnan; Lee, Jin Hyung

    2013-01-01

    Optogenetic functional magnetic resonance imaging (ofMRI) technology enables cell-type specific, temporally precise neuronal control and accurate, in vivo readout of resulting activity across the whole brain. With the ability to precisely control excitation and inhibition parameters, and to accurately record the resulting activity, there is an increased need for a high-throughput method to bring the ofMRI studies to their full potential. In this paper, an advanced system that can allow real-time fMRI with interactive control and analysis in a fraction of the MRI acquisition repetition time (TR) is proposed. With such high processing speed, sufficient time will be available for integration of future developments that can further enhance ofMRI data quality or better streamline the study. We designed and implemented a highly optimized, massively parallel system using graphics processing unit (GPU)s which achieves reconstruction, motion correction, and analysis of 3D volume data in approximately 12.80 ms. As a result, with a 750 ms TR and 4 interleaf fMRI acquisition, we can now conduct sliding window reconstruction, motion correction, analysis and display in approximately 1.7% of the TR. Therefore, a significant amount of time can now be allocated to integrating advanced but computationally intensive methods that can enable higher image quality and better analysis results all within a TR. Utilizing the proposed high-throughput imaging platform with sliding window reconstruction, we were also able to observe the much-debated initial dips in our ofMRI data. Combined with methods to further improve SNR, the proposed system will enable efficient real-time, interactive, high-throughput ofMRI studies. PMID:23747482

  18. Functional magnetic resonance imaging adaptation reveals a noncategorical representation of hue in early visual cortex

    PubMed Central

    Persichetti, Andrew S.; Thompson-Schill, Sharon L.; Butt, Omar H.; Brainard, David H.; Aguirre, Geoffrey K.

    2015-01-01

    Color names divide the fine-grained gamut of color percepts into discrete categories. A categorical transition must occur somewhere between the initial encoding of the continuous spectrum of light by the cones and the verbal report of the name of a color stimulus. Here, we used a functional magnetic resonance imaging (fMRI) adaptation experiment to examine the representation of hue in the early visual cortex. Our stimuli varied in hue between blue and green. We found in the early visual areas (V1, V2/3, and hV4) a smoothly increasing recovery from adaptation with increasing hue distance between adjacent stimuli during both passive viewing (Experiment 1) and active categorization (Experiment 2). We examined the form of the adaptation effect and found no evidence that a categorical representation mediates the release from adaptation for stimuli that cross the blue–green color boundary. Examination of the direct effect of stimulus hue on the fMRI response did, however, reveal an enhanced response to stimuli near the blue–green category border. This was largest in hV4 and when subjects were engaged in active categorization of the stimulus hue. In contrast with a recent report from another laboratory (Bird, Berens, Horner, & Franklin, 2014), we found no evidence for a categorical representation of color in the middle frontal gyrus. A post hoc whole-brain analysis, however, revealed several regions in the frontal cortex with a categorical effect in the adaptation response. Overall, our results support the idea that the representation of color in the early visual cortex is primarily fine grained and does not reflect color categories. PMID:26024465

  19. How Doctors Generate Diagnostic Hypotheses: A Study of Radiological Diagnosis with Functional Magnetic Resonance Imaging

    PubMed Central

    Melo, Marcio; Scarpin, Daniel J.; Amaro, Edson; Passos, Rodrigo B. D.; Sato, João R.; Friston, Karl J.; Price, Cathy J.

    2011-01-01

    Background In medical practice, diagnostic hypotheses are often made by physicians in the first moments of contact with patients; sometimes even before they report their symptoms. We propose that generation of diagnostic hypotheses in this context is the result of cognitive processes subserved by brain mechanisms that are similar to those involved in naming objects or concepts in everyday life. Methodology and Principal Findings To test this proposal we developed an experimental paradigm with functional magnetic resonance imaging (fMRI) using radiological diagnosis as a model. Twenty-five radiologists diagnosed lesions in chest X-ray images and named non-medical targets (animals) embedded in chest X-ray images while being scanned in a fMRI session. Images were presented for 1.5 seconds; response times (RTs) and the ensuing cortical activations were assessed. The mean response time for diagnosing lesions was 1.33 (SD ±0.14) seconds and 1.23 (SD ±0.13) seconds for naming animals. 72% of the radiologists reported cogitating differential diagnoses during trials (3.5 seconds). The overall pattern of cortical activations was remarkably similar for both types of targets. However, within the neural systems shared by both stimuli, activation was significantly greater in left inferior frontal sulcus and posterior cingulate cortex for lesions relative to animals. Conclusions Generation of diagnostic hypotheses and differential diagnoses made through the immediate visual recognition of clinical signs can be a fast and automatic process. The co-localization of significant brain activation for lesions and animals suggests that generating diagnostic hypotheses for lesions and naming animals are served by the same neuronal systems. Nevertheless, diagnosing lesions was cognitively more demanding and associated with more activation in higher order cortical areas. These results support the hypothesis that medical diagnoses based on prompt visual recognition of clinical signs and naming in everyday life are supported by similar brain systems. PMID:22194902

  20. Active control of the volume acquisition noise in functional magnetic resonance imaging: method and psychoacoustical evaluation.

    PubMed

    Chambers, J; Akeroyd, M A; Summerfield, A Q; Palmer, A R

    2001-12-01

    Functional magnetic resonance imaging (fMRI) provides a noninvasive tool for observing correlates of neural activity in the brain while a subject listens to sound. However, intense acoustic noise is generated in the process of capturing MR images. This noise stimulates the auditory nervous system, limiting the dynamic range available for displaying stimulus-driven activity. The noise is potentially damaging to hearing and is distracting for the subject. In an active noise control (ANC) system, a reference sample of a noise is processed to form a sound which adds destructively with the noise at the listener's ear. We describe an implementation of ANC in the electromagnetically hostile and physically compact MRI scanning environment. First, a prototype system was evaluated psychoacoustically in the laboratory, using the electrical drive to a noise-generating loudspeaker as the reference. This system produced 10-20 dB of subjective noise-reduction between 250 Hz and 1 kHz, and smaller amounts at higher frequencies. The system was modified to operate in a real MR scanner where the reference was obtained by recording the acoustic scanner noise. Objective reduction by 30-40 dB of the most intense component in scanner noises was realized between 500 Hz and 3500 Hz, and subjective reduction of 12 dB and 5 dB in tests at frequencies of 600 Hz and at 1.9 kHz, respectively. Although the benefit of ANC is limited by transmission paths to the cochlea other than air-conduction routes from the auditory meatus, ANC achieves worthwhile attenuation even in the frequency range of maximum bone conduction (1.5-2 kHz). ANC should, therefore, be generally useful during auditory fMRI. PMID:11785805

  1. Functional magnetic resonance imaging adaptation reveals a noncategorical representation of hue in early visual cortex.

    PubMed

    Persichetti, Andrew S; Thompson-Schill, Sharon L; Butt, Omar H; Brainard, David H; Aguirre, Geoffrey K

    2015-05-01

    Color names divide the fine-grained gamut of color percepts into discrete categories. A categorical transition must occur somewhere between the initial encoding of the continuous spectrum of light by the cones and the verbal report of the name of a color stimulus. Here, we used a functional magnetic resonance imaging (fMRI) adaptation experiment to examine the representation of hue in the early visual cortex. Our stimuli varied in hue between blue and green. We found in the early visual areas (V1, V2/3, and hV4) a smoothly increasing recovery from adaptation with increasing hue distance between adjacent stimuli during both passive viewing (Experiment 1) and active categorization (Experiment 2). We examined the form of the adaptation effect and found no evidence that a categorical representation mediates the release from adaptation for stimuli that cross the blue-green color boundary. Examination of the direct effect of stimulus hue on the fMRI response did, however, reveal an enhanced response to stimuli near the blue-green category border. This was largest in hV4 and when subjects were engaged in active categorization of the stimulus hue. In contrast with a recent report from another laboratory (Bird, Berens, Horner, & Franklin, 2014), we found no evidence for a categorical representation of color in the middle frontal gyrus. A post hoc whole-brain analysis, however, revealed several regions in the frontal cortex with a categorical effect in the adaptation response. Overall, our results support the idea that the representation of color in the early visual cortex is primarily fine grained and does not reflect color categories. PMID:26024465

  2. Broadband Local Field Potentials Correlate with Spontaneous Fluctuations in Functional Magnetic Resonance Imaging Signals in the Rat Somatosensory Cortex Under Isoflurane Anesthesia

    PubMed Central

    Pan, Wen-Ju; Thompson, Garth; Magnuson, Matthew; Majeed, Waqas; Jaeger, Dieter

    2011-01-01

    Abstract Resting-state functional magnetic resonance imaging (fMRI) is widely used for exploring spontaneous brain activity and large-scale networks; however, the neural processes underlying the observed resting-state fMRI signals are not fully understood. To investigate the neural correlates of spontaneous low-frequency fMRI fluctuations and functional connectivity, we developed a rat model of simultaneous fMRI and multiple-site intracortical neural recordings. This allowed a direct comparison to be made between the spontaneous signals and interhemispheric connectivity measured with the two modalities. Results show that low-frequency blood oxygen level-dependent (BOLD) fluctuations (<0.1?Hz) correlate significantly with slow power modulations (<0.1?Hz) of local field potentials (LFPs) in a broad frequency range (1–100?Hz) under isoflurane anesthesia (1%–1.8%). Peak correlation occurred between neural and hemodynamic activity when the BOLD signal was delayed by ?4?sec relative to the LFP signal. The spatial location and extent of correlation was highly reproducible across studies, with the maximum correlation localized to a small area surrounding the site of microelectrode recording and to the homologous area in the contralateral hemisphere for most rats. Interhemispheric connectivity was calculated using BOLD correlation and band-limited LFP (1–4, 4–8, 8–14, 14–25, 25–40, and 40–100?Hz) coherence. Significant coherence was observed for the slow power changes of all LFP frequency bands as well as in the low-frequency BOLD data. A preliminary investigation of the effect of anesthesia on interhemispheric connectivity indicates that coherence in the high-frequency LFP bands declines with increasing doses of isoflurane, whereas coherence in the low-frequency LFP bands and the BOLD signal increases. These findings suggest that resting-state fMRI signals might be a reflection of broadband LFP power modulation, at least in isoflurane-anesthetized rats. PMID:22433008

  3. Towards neural correlates of auditory stimulus processing: A simultaneous auditory evoked potentials and functional magnetic resonance study using an odd-ball paradigm

    PubMed Central

    Milner, Rafa?; Rusiniak, Mateusz; Lewandowska, Monika; Wolak, Tomasz; Ganc, Ma?gorzata; Pi?tkowska-Janko, Ewa; Bogorodzki, Piotr; Skar?y?ski, Henryk

    2014-01-01

    Background The neural underpinnings of auditory information processing have often been investigated using the odd-ball paradigm, in which infrequent sounds (deviants) are presented within a regular train of frequent stimuli (standards). Traditionally, this paradigm has been applied using either high temporal resolution (EEG) or high spatial resolution (fMRI, PET). However, used separately, these techniques cannot provide information on both the location and time course of particular neural processes. The goal of this study was to investigate the neural correlates of auditory processes with a fine spatio-temporal resolution. A simultaneous auditory evoked potentials (AEP) and functional magnetic resonance imaging (fMRI) technique (AEP-fMRI), together with an odd-ball paradigm, were used. Material/Methods Six healthy volunteers, aged 20–35 years, participated in an odd-ball simultaneous AEP-fMRI experiment. AEP in response to acoustic stimuli were used to model bioelectric intracerebral generators, and electrophysiological results were integrated with fMRI data. Results fMRI activation evoked by standard stimuli was found to occur mainly in the primary auditory cortex. Activity in these regions overlapped with intracerebral bioelectric sources (dipoles) of the N1 component. Dipoles of the N1/P2 complex in response to standard stimuli were also found in the auditory pathway between the thalamus and the auditory cortex. Deviant stimuli induced fMRI activity in the anterior cingulate gyrus, insula, and parietal lobes. Conclusions The present study showed that neural processes evoked by standard stimuli occur predominantly in subcortical and cortical structures of the auditory pathway. Deviants activate areas non-specific for auditory information processing. PMID:24413019

  4. Magnetic resonance imaging of thyroid nodules

    SciTech Connect

    Kroop, S.A.; Margouleff, D.; Stein, H.L.; Zanzi, I.; Susin, M.; Goldman, M.A.

    1985-05-01

    The capacity of Magnetic Resonance (MR) imaging to characterize the nature of palpable thyroid nodules was prospectively evaluated in 9 patients. Seven nodules were nonfunctioning and 2 showed function on radio-iodine Nuclear Medicine (NM) scans. Each patient underwent high-resolution real time ultrasound (US) examination followed by MR imaging with a 0.6 Tesla superconducting whole body coil utilizing T/sub 1/ and T/sub 2/ weighted inversion recovery and spin-echo pulse sequences in coronal, transverse and sagittal planes. All NM, US and MR studies were evaluated independently by each of two physicians. Diagnoses were established by surgical pathology (n=7) or by radiologic and clinical correlation (n=2). There were 3 cases of solitary adenoma, 4 cases of adenomatous goiter, 1 case of papillary carcinoma and 1 case of epidermoid carcinoma. Lesions demonstrated variable signal intensity on T/sub 1/ weighted images. All lesions demonstrated nonspecific increased signal intensity on T/sub 2/ weighted images. One malignancy was correctly diagnosed by the identification of adjacent cervical lymph nodes of increased signal intensity and another by demonstration of tracheal invasion on MR images, both not visible by other imaging modalities. Regions of hemorrhage and cystic degeneration as well as additional non-palpable thyroid nodules could be detected on MR images. Vascular displacement, tracheal compression and deviation, and substernal thyroid extension were also well demonstrated. The findings suggest that qualitative assessment of MR signal intensity alone cannot reliably differentiate benign from malignant thyroid lesions, but that MR images can provide other useful information to aid in this differentiation.

  5. Small Animal Imaging with Magnetic Resonance Microscopy

    PubMed Central

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

    2009-01-01

    Small animal magnetic resonance microscopy (MRM) has evolved significantly from testing the boundaries of imaging physics to its expanding use today as a tool in non-invasive biomedical investigations. This review is intended to capture the state-of-the-art in MRM for scientists who may be unfamiliar with this modality, but who want to apply its capabilities to their research. We therefore include a brief review of MR concepts and methods of animal handling and support before covering a range of MRM applications including the heart, lung, brain, and the emerging field of MR histology. High-resolution anatomical imaging reveals increasingly exquisite detail in healthy animals and subtle architectural aberrations that occur in genetically altered models. Resolution of 100 µm in all dimensions is now routinely attained in living animals, and 10 µm3 is feasible in fixed specimens. Such images almost rival conventional histology while allowing the object to be viewed interactively in any plane. MRM is now increasingly used to provide functional information in living animals. Images of the beating heart, breathing lung, and functioning brain can be recorded. While clinical MRI focuses on diagnosis, MRM is used to reveal fundamental biology or to non-invasively measure subtle changes in the structure or function of organs during disease progression or in response to experimental therapies. The ability of MRM to provide a detailed functional and anatomical picture in rats and mice, and to track this picture over time, makes it a promising platform with broad applications in biomedical research. PMID:18172332

  6. Tools for cardiovascular magnetic resonance imaging

    PubMed Central

    Krishnamurthy, Ramkumar; Cheong, Benjamin

    2014-01-01

    In less than fifteen years, as a non-invasive imaging option, cardiovascular MR has grown from a being a mere curiosity to becoming a widely used clinical tool for evaluating cardiovascular disease. Cardiovascular magnetic resonance imaging (CMRI) is now routinely used to study myocardial structure, cardiac function, macro vascular blood flow, myocardial perfusion, and myocardial viability. For someone entering the field of cardiac MR, this rapid pace of development in the field of CMRI might make it difficult to identify a cohesive starting point. In this brief review, we have attempted to summarize the key cardiovascular imaging techniques that have found widespread clinical acceptance. In particular, we describe the essential cardiac and respiratory gating techniques that form the backbone of all cardiovascular imaging methods. It is followed by four sections that discuss: (I) the gradient echo techniques that are used to assess ventricular function; (II) black-blood turbo spin echo (SE) methods used for morphologic assessment of the heart; (III) phase-contrast based techniques for the assessment of blood flow; and (IV) CMR methods for the assessment of myocardial ischemia and viability. In each section, we briefly summarize technical considerations relevant to the clinical use of these techniques, followed by practical information for its clinical implementation. In each of those four areas, CMRI is considered either as the benchmark imaging modality against which the diagnostic performance of other imaging modalities are compared against, or provides a complementary capability to existing imaging techniques. We have deliberately avoided including cutting-edge CMR imaging techniques practiced at few academic centers, and restricted our discussion to methods that are widely used and are likely to be available in a clinical setting. Our hope is that this review would propel an interested reader toward more comprehensive reviews in the literature. PMID:24834409

  7. Use of magnetic resonance imaging in pharmacogenomics.

    PubMed

    Viviani, Roberto; Lehmann, Marie-Louise; Stingl, Julia C

    2014-04-01

    Because of the large variation in the response to psychoactive medication, many studies have attempted to uncover genetic factors that determine response. While considerable knowledge exists on the large effects of genetic polymorphisms on pharmacokinetics and plasma concentrations of drugs, effects of the concentration at the target site and pharmacodynamic effects on brain functions in disease are much less known. This article reviews the role of magnetic resonance imaging (MRI) to visualize response to medication in brain behaviour circuits in vivo in humans and assess the influence of pharmacogenetic factors. Two types of studies have been used to characterize effects of medication and genetic variation. In task-related activation studies the focus is on changes in the activity of a neural circuit associated with a specific psychological process. The second type of study investigates resting state perfusion. These studies provide an assessment of vascular changes associated with bioavailability of drugs in the brain, but may also assess changes in neural activity after binding of centrally active agents. Task-related pharmacogenetic studies of cognitive function have characterized the effects in the prefrontal cortex of genetic polymorphisms of dopamine receptors (DRD2), metabolic enzymes (COMT) and in the post-synaptic signalling cascade under the administration of dopamine agonists and antagonists. In contrast, pharmacogenetic imaging with resting state perfusion is still in its infancy. However, the quantitative nature of perfusion imaging, its non-invasive character and its repeatability might be crucial assets in visualizing the effects of medication in vivo in man during therapy. PMID:23802603

  8. Magnetic Resonance Imaging in Postprostatectomy Radiotherapy Planning

    SciTech Connect

    Sefrova, Jana, E-mail: sefrova@post.cz [Department of Oncology and Radiotherapy, University Hospital Hradec Kralove, Hradec Kralove (Czech Republic); Odrazka, Karel [Department of Clinical and Radiation Oncology, Multiscan and Pardubice Regional Hospital, Pardubice (Czech Republic); First and Third Faculty of Medicine, Charles University in Prague, Prague (Czech Republic); Paluska, Petr [Department of Oncology and Radiotherapy, University Hospital Hradec Kralove, Hradec Kralove (Czech Republic); Belobradek, Zdenek [Department of Radiology, University Hospital Hradec Kralove, Hradec Kralove (Czech Republic); Brodak, Milos [Department of Urology, University Hospital Hradec Kralove, Hradec Kralove (Czech Republic); Dolezel, Martin [Department of Clinical and Radiation Oncology, Multiscan and Pardubice Regional Hospital, Pardubice (Czech Republic); First and Third Faculty of Medicine, Charles University in Prague, Prague (Czech Republic); Prosvic, Petr [Department of Urology, Regional Hospital Nachod, Nachod (Czech Republic); Macingova, Zuzana; Vosmik, Milan [Department of Oncology and Radiotherapy, University Hospital Hradec Kralove, Hradec Kralove (Czech Republic); Hoffmann, Petr [Department of Radiology, University Hospital Hradec Kralove, Hradec Kralove (Czech Republic); Louda, Miroslav [Department of Urology, University Hospital Hradec Kralove, Hradec Kralove (Czech Republic); Nejedla, Anna [Department of Oncology and Radiotherapy, University Hospital Hradec Kralove, Hradec Kralove (Czech Republic)

    2012-02-01

    Purpose: To investigate whether the use of magnetic resonance imaging (MRI) in prostate bed treatment planning could influence definition of the clinical target volume (CTV) and organs at risk. Methods and Materials: A total of 21 consecutive patients referred for prostate bed radiotherapy were included in the present retrospective study. The CTV was delineated according to the European Organization for Research and Treatment of Cancer recommendations on computed tomography (CT) and T{sub 1}-weighted (T{sub 1}w) and T{sub 2}-weighted (T{sub 2}w) MRI. The CTV magnitude, agreement, and spatial differences were evaluated on the planning CT scan after registration with the MRI scans. Results: The CTV was significantly reduced on the T{sub 1}w and T{sub 2}w MRI scans (13% and 9%, respectively) compared with the CT scans. The urinary bladder was drawn smaller on the CT scans and the rectum was smaller on the MRI scans. On T{sub 1}w MRI, the rectum and urinary bladder were delineated larger than on T{sub 2}w MRI. Minimal agreement was observed between the CT and T{sub 2}w images. The main spatial differences were measured in the superior and superolateral directions in which the CTV on the MRI scans was 1.8-2.9 mm smaller. In the posterior and inferior border, no difference was seen between the CT and T{sub 1}w MRI scans. On the T{sub 2}w MRI scans, the CTV was larger in these directions (by 1.3 and 1.7 mm, respectively). Conclusions: The use of MRI in postprostatectomy radiotherapy planning resulted in a reduction of the CTV. The main differences were found in the superior part of the prostate bed. We believe T{sub 2}w MRI enables more precise definition of prostate bed CTV than conventional planning CT.

  9. Magnetic Resonance Imaging–guided Vascular Interventions

    PubMed Central

    Ozturk, Cengizhan; Guttman, Michael; McVeigh, Elliot R.; Lederman, Robert J.

    2007-01-01

    Magnetic resonance imaging (MRI), which provides superior soft-tissue imaging and no known harmful effects, has the potential as an alternative modality to guide various medical interventions. This review will focus on MR-guided endovascular interventions and present its current state and future outlook. In the first technical part, enabling technologies such as developments in fast imaging, catheter devices, and visualization techniques are examined. This is followed by a clinical survey that includes proof-of-concept procedures in animals and initial experience in human subjects. In preclinical experiments, MRI has already proven to be valuable. For example, MRI has been used to guide and track targeted cell delivery into or around myocardial infarctions, to guide atrial septal puncture, and to guide the connection of portal and systemic venous circulations. Several investigational MR-guided procedures have already been reported in patients, such as MR-guided cardiac catheterization, invasive imaging of peripheral artery atheromata, selective intraarterial MR angiography, and preliminary angioplasty and stent placement. In addition, MR-assisted transjugular intrahepatic portosystemic shunt procedures in patients have been shown in a novel hybrid double-doughnut x-ray/MRI system. Numerous additional investigational human MR-guided endovascular procedures are now underway in several medical centers around the world. There are also significant hurdles: availability of clinical-grade devices, device-related safety issues, challenges to patient monitoring, and acoustic noise during imaging. The potential of endovascular interventional MRI is great because as a single modality, it combines 3-dimensional anatomic imaging, device localization, hemodynamics, tissue composition, and function. PMID:16924170

  10. Use of magnetic resonance imaging in pharmacogenomics

    PubMed Central

    Viviani, Roberto; Lehmann, Marie-Louise; Stingl, Julia C

    2014-01-01

    Because of the large variation in the response to psychoactive medication, many studies have attempted to uncover genetic factors that determine response. While considerable knowledge exists on the large effects of genetic polymorphisms on pharmacokinetics and plasma concentrations of drugs, effects of the concentration at the target site and pharmacodynamic effects on brain functions in disease are much less known. This article reviews the role of magnetic resonance imaging (MRI) to visualize response to medication in brain behaviour circuits in vivo in humans and assess the influence of pharmacogenetic factors. Two types of studies have been used to characterize effects of medication and genetic variation. In task-related activation studies the focus is on changes in the activity of a neural circuit associated with a specific psychological process. The second type of study investigates resting state perfusion. These studies provide an assessment of vascular changes associated with bioavailability of drugs in the brain, but may also assess changes in neural activity after binding of centrally active agents. Task-related pharmacogenetic studies of cognitive function have characterized the effects in the prefrontal cortex of genetic polymorphisms of dopamine receptors (DRD2), metabolic enzymes (COMT) and in the post-synaptic signalling cascade under the administration of dopamine agonists and antagonists. In contrast, pharmacogenetic imaging with resting state perfusion is still in its infancy. However, the quantitative nature of perfusion imaging, its non-invasive character and its repeatability might be crucial assets in visualizing the effects of medication in vivo in man during therapy. PMID:23802603

  11. Magnetic resonance findings in leucodystrophies and MS.

    PubMed

    Labauge, P

    2009-06-01

    White matter diseases are a frequent diagnosis problem in adult patients. They are divided into leucodystrophy, defined by abnormal white matter from the beginning, and leucoencephalopathy, with an initial normal white matter. In addition, two different natures have to be considered: vascular and non-vascular. Vascular diseases are mainly acquired and related to atherosclerosis. Genetic vascular disorders are mostly secondary to Notch3 mutations, defined as cerebral autosomal dominant arteriopathy with subcortical infarcts and leucoencephalopathy (CADASIL). Occurrence of leucoaraiosis and lacunae on T2 sequences, and microbleeds on Gradient Echo sequences, strongly suggest this diagnosis. Some magnetic resonance (MR) patterns can help to identify genetic leucodystrophies, such as childhood ataxia with central nervous system hypomyelination/leucoencephalopathy with vanishing white matter disease (progressive rarefaction and cystic degeneration of the affected white matter, replaced by water); Alexander disease (hypointense signals on T2 sequences involving grey matter, brainstem and cervical cord, with marked atrophy); megalencephalic leucoencephalopathy with subcortical cysts (diffuse, symmetrical white matter lesions, with constant frontoparietal and anterotemporal subcortical cysts); leucoencephalopathy with brainstem and spinal cord involvement and high lactates syndrome (extensive demyelination, involvement of the brainstem, i.e. cerebellar peduncles, intraparenchymal and mesencephalic trigeminal nerves and spinal cord, mainly in the lateral corticospinal tracts and dorsal columns). Half of the genetic adult leucodystrophies remain without any precise diagnosis. This review describes MR in the adult leucoencephalopathies and in multiple sclerosis (MS). The first part will focus on MR patterns of vascular and nonvascular adult leucoencephalopathies, the second part on MR findings in MS and MS-related diseases. Specific MR patterns in both diseases will be summarized and compared. PMID:19671368

  12. Diagnostic Accuracy of Clinical Assessment, Magnetic Resonance Imaging, Magnetic Resonance Arthrography, and Intra-Articular Injection in Hip Arthroscopy Patients

    Microsoft Academic Search

    J. W. Thomas Byrd; Kay S. Jones

    2004-01-01

    Background: Hip arthroscopy has defined elusive causes of hip pain.Hypothesis\\/Purpose: It is postulated that the reliability of various investigative methods is inconsistent. The purpose of this study is to evaluate the diagnostic accuracy of these methods.Study Design: Retrospective review of prospectively collected data.Methods: Five parameters were assessed in 40 patients: clinical assessment, high-resolution magnetic resonance imaging, magnetic resonance imaging with

  13. Least Squares Magnetic-Field Optimization for Portable Nuclear Magnetic Resonance Magnet Design

    SciTech Connect

    Paulsen, Jeffrey L; Franck, John; Demas, Vasiliki; Bouchard, Louis-S.

    2008-03-27

    Single-sided and mobile nuclear magnetic resonance (NMR) sensors have the advantages of portability, low cost, and low power consumption compared to conventional high-field NMR and magnetic resonance imaging (MRI) systems. We present fast, flexible, and easy-to-implement target field algorithms for mobile NMR and MRI magnet design. The optimization finds a global optimum ina cost function that minimizes the error in the target magnetic field in the sense of least squares. When the technique is tested on a ring array of permanent-magnet elements, the solution matches the classical dipole Halbach solution. For a single-sided handheld NMR sensor, the algorithm yields a 640 G field homogeneous to 16 100 ppm across a 1.9 cc volume located 1.5 cm above the top of the magnets and homogeneous to 32 200 ppm over a 7.6 cc volume. This regime is adequate for MRI applications. We demonstrate that the homogeneous region can be continuously moved away from the sensor by rotating magnet rod elements, opening the way for NMR sensors with adjustable"sensitive volumes."

  14. Magnetic resonance velocimetry: applications of magnetic resonance imaging in the measurement of fluid motion

    NASA Astrophysics Data System (ADS)

    Elkins, Christopher J.; Alley, Marcus T.

    2007-12-01

    Magnetic resonance velocimetry (MRV) is a non-invasive technique capable of measuring the three-component mean velocity field in complex three-dimensional geometries with either steady or periodic boundary conditions. The technique is based on the phenomenon of nuclear magnetic resonance (NMR) and works in conventional magnetic resonance imaging (MRI) magnets used for clinical imaging. Velocities can be measured along single lines, in planes, or in full 3D volumes with sub-millimeter resolution. No optical access or flow markers are required so measurements can be obtained in clear or opaque MR compatible flow models and fluids. Because of its versatility and the widespread availability of MRI scanners, MRV is seeing increasing application in both biological and engineering flows. MRV measurements typically image the hydrogen protons in liquid flows due to the relatively high intrinsic signal-to-noise ratio (SNR). Nonetheless, lower SNR applications such as fluorine gas flows are beginning to appear in the literature. MRV can be used in laminar and turbulent flows, single and multiphase flows, and even non-isothermal flows. In addition to measuring mean velocity, MRI techniques can measure turbulent velocities, diffusion coefficients and tensors, and temperature. This review surveys recent developments in MRI measurement techniques primarily in turbulent liquid and gas flows. A general description of MRV provides background for a discussion of its accuracy and limitations. Techniques for decreasing scan time such as parallel imaging and partial k-space sampling are discussed. MRV applications are reviewed in the areas of physiology, biology, and engineering. Included are measurements of arterial blood flow and gas flow in human lungs. Featured engineering applications include the scanning of turbulent flows in complex geometries for CFD validation, the rapid iterative design of complex internal flow passages, velocity and phase composition measurements in multiphase flows, and the scanning of flows through porous media. Temperature measurements using MR thermometry are discussed. Finally, post-processing methods are covered to demonstrate the utility of MRV data for calculating relative pressure fields and wall shear stresses.

  15. Effects of Acute Nicotine Abstinence on Cue-elicited Ventral Striatum\\/Nucleus Accumbens Activation in Female Cigarette Smokers: A Functional Magnetic Resonance Imaging Study

    Microsoft Academic Search

    Sean P. David; Marcus R. Munafò; Heidi Johansen-Berg; James MacKillop; Lawrence H. Sweet; Ronald A. Cohen; Raymond Niaura; Robert D. Rogers; Paul M. Matthews; Robert T. Walton

    2007-01-01

    To achieve greater understanding of the brain mechanisms underlying nicotine craving in female smokers, we examined the influence\\u000a of nicotine non-abstinence vs. acute nicotine abstinence on cue-elicited activation of the ventral striatum. Eight female\\u000a smokers underwent an event-related functional magnetic resonance imaging (fMRI) paradigm presenting randomized sequences of\\u000a smoking-related and non-smoking related pictures. Participants were asked to indicate by a

  16. fMRI for mapping language networks in neurosurgical cases

    PubMed Central

    Gupta, Santosh S

    2014-01-01

    Evaluating language has been a long-standing application in functional magnetic resonance imaging (fMRI) studies, both in research and clinical circumstances, and still provides challenges. Localization of eloquent areas is important in neurosurgical cases, so that there is least possible damage to these areas during surgery, maintaining their function postoperatively, therefore providing good quality of life to the patient. Preoperative fMRI study is a non-invasive tool to localize the eloquent areas, including language, with other traditional methods generally used being invasive and at times perilous. In this article, we describe methods and various paradigms to study the language areas, in clinical neurosurgical cases, along with illustrations of cases from our institute. PMID:24851003

  17. Tagged magnetic resonance imaging of the heart: a survey

    Microsoft Academic Search

    Leon Axel; Albert Montillo; Daniel Kim

    2005-01-01

    Magnetic resonance imaging (MRI) of the heart with magnetization tagging provides a potentially useful new way to assess car-diac mechanical function, through revealing the local motion of otherwise indistinguishable portions of the heart wall. While still an evolving area, tagged cardiac MRI is already able to provide novel quantitative information on cardiac function. Exploiting this potential requires developing tailored methods

  18. Design of Optimized Gradient Coils for Magnetic Resonance Imaging

    Microsoft Academic Search

    Yoseph Shiferaw

    1990-01-01

    A gradient coil system for use in magnetic resonance imaging was designed and built. The geometry of the coil system was determined by computer simulation. An optimized variation of Anderson coils was chosen as a suitable configuration. This gradient coil system will be used in a Varian magnet system with a gap width of 4.4 cm.

  19. Design of gradient coils for magnetic resonance imaging

    Microsoft Academic Search

    K. Adamiak; B. K. Rutt; W. J. Dabrowski

    1992-01-01

    A numerical technique for designing gradient coils used in magnetic resonance imaging is presented. It is assumed that the coil consists of a finite number of polygonal turns, each carrying identical current. Coordinates of the vertices defining the turns are determined to minimize the mean-square deviation of the actual magnetic flux density from the ideal linear distribution. The zeroth-order Powell

  20. Artificial magnetic metamaterial design by using spiral resonators

    Microsoft Academic Search

    Juan D. Baena; Ricardo Marqués; Francisco Medina; Jesús Martel

    2004-01-01

    A metallic planar particle, that will be called spiral resonator (SR), is introduced as a useful artificial atom for artificial magnetic media design and fabrication. A simple theoretical model which provides the most relevant properties and parameters of the SR is presented. The model is validated by both electromagnetic simulation and experiments. The applications of SR's include artificial negative magnetic

  1. Acquisition of electrophysiologic signals during magnetic resonance imaging.

    PubMed

    Parker, J M; Alger, J R; Woo, M A; Spriggs, D; Harper, R M

    1999-12-15

    We describe a low cost system for acquiring electrophysiological signals during magnetic resonance imaging. The system consists of high common-mode-rejection and low noise operational amplifiers, coupled by fiber optic cables to a receiver located at the periphery of the magnetic field. The system minimizes noise introduction which would contaminate image signals. PMID:10617174

  2. Influence of a magnetic field on quartz crystal resonators

    Microsoft Academic Search

    R. Brendel

    1996-01-01

    The magnetic sensitivity of quartz crystal resonators is a consequence of the ferromagnetic properties of the metal used as support for the vibrating plate. Various magneto-mechanic interactions can contribute to the overall sensitivity, the most important of which is shown to be the change in Young's modulus of the spring material submitted to a magnetic field, which in turn modifies

  3. PERTURBING A SYMMETRIC RESONANCE: THE MAGNETIC SPHERICAL PENDULUM

    E-print Network

    Montaldi, James

    PERTURBING A SYMMETRIC RESONANCE: THE MAGNETIC SPHERICAL PENDULUM JAMES MONTALDI Institut Non, such as the spherical pendulum. Perturbing such a system by breaking the symmetry (e.g. adding a magnetic term) creates. Introduction The spherical pendulum is a 2-degree of freedom Hamiltonian system with O(2) symmetry. The stable

  4. Poststroke aphasia recovery assessed with functional magnetic resonance imaging and a picture identification task.

    PubMed

    Szaflarski, Jerzy P; Eaton, Kenneth; Ball, Angel L; Banks, Christi; Vannest, Jennifer; Allendorfer, Jane B; Page, Stephen; Holland, Scott K

    2011-01-01

    Stroke patients often display deficits in language function, such as correctly naming objects. Our aim was to evaluate the reliability and the patterns of poststroke language recovery using a picture identification task during functional magnetic resonance imaging (fMRI) at 4 T. Four healthy subjects and 4 subjects with left middle cerebral artery stroke with chronic (>1 year) aphasia were enrolled in the study. In each subject, 10 fMRI scans were performed over a 10-week period using a picture-identification task. The active condition involved presenting subject with a panel of 4 figures (eg, drawings of 4 animals) every 6 seconds and asking the subject to indicate which figure matched the written name in the center. The control condition was a same/different judgment task with pairs of geometric figures (squares, octagons, or combination) presented every 6 seconds. Thirty-second active/control blocks were repeated 5 times each, and responses were recorded. The stoke subjects and controls had similar demographic characteristics, including age (46 vs 53 years), personal handedness (Edinburg Handedness Inventory, 89 vs 95), familial handedness (93 vs 95), and years of education (14.3 vs 14.8). For the active condition, the controls performed better than the stroke subjects (97.7% vs 89.1%; P < .001); the 2 groups performed similarly for the control condition (99.5% vs 98.8%; P = .23). On fMRI, the controls exhibited bilateral, L > R positive blood oxygenation level-dependent (BOLD) activations in frontal and temporal language areas and symmetric retrosplenial and posterior cingulate areas and symmetric negative BOLD activations in bilateral frontotemporal language networks. In contrast, the stroke subjects exhibited positive BOLD activations predominantly in peristroke areas and negative BOLD activations in the unaffected (right) hemisphere. Both groups displayed high activation reliability (as measured by the intraclass correlation coefficient [ICC]) in the left frontal and temporal language areas, although in the stroke subjects the ICC in the frontal regions was spread over a much larger peristroke area. This study documents the utility of the picture-identification task for poststroke language recovery evaluation. Our data suggest that adult stroke patients use functional peristroke areas to perform language functions. PMID:20719532

  5. Formation of multiple Alfvenic resonance layers in magnetic reconnection

    NASA Astrophysics Data System (ADS)

    Ma, Z.

    2013-12-01

    Reconnection dynamics and formation of Alfvenic resonance layers under different super-Alfvenic shear flows are systematically studied through incompressible MHD simulation. It is found that Alfvenic resonance layers is formed in the inflow region as the island develops. Different shear flow profiles can lead to one or two pairs of Alfvenic resonance layers. The appearance of Alfven layers usually suppresses the development of magnetic reconnection and modulates the structure of the reconnection layer. The suppressing effect depends largely on the intensity of the Alfvenic resonance layers and the distance between the two layers. For the case with the separation of Alfvenic resonance layers less than the current sheet thickness, the turbulence associated with KH instability strongly develops and then leads to fast magnetic reconnection.

  6. A novel approach to activation detection in fMRI based on empirical mode decomposition.

    PubMed

    Zheng, Tianxiang; Cai, Mingbo; Jiang, Tianzi

    2010-12-01

    This article presents a novel method for activation detection in task-related functional magnetic resonance imaging (fMRI) based on the Empirical Mode Decomposition (EMD) algorithm. The basic concept stems mainly from the idea that the EMD performs well in isolating the imbedded stimulus from the activated Blood Oxygen Level Dependent (BOLD) signal. The power of the proposed method was compared with the General Linear Model (GLM), spatial Independent Component Analysis (ICA) and Region Growing (RG) methods on simulated and real datasets. Experimental results suggest an almost identical performance for the proposed method compared with the standard approach of fMRI signal detection (the GLM), which indicates that it is to become a viable alternative to fMRI analysis. PMID:21213412

  7. fMRI investigation of the cognitive structure of the Concealed Information Test.

    PubMed

    Hakun, J G; Seelig, D; Ruparel, K; Loughead, J W; Busch, E; Gur, R C; Langleben, D D

    2008-01-01

    We studied the cognitive basis of the functional magnetic resonance imaging (fMRI) pattern of deception in three participants performing the Concealed Information Test (CIT). In all participants, the prefrontoparietal lie activation was similar to the pattern derived from the meta-analysis (N = 40) of our previously reported fMRI CIT studies and was unchanged when the lie response was replaced with passive viewing of the target items. When lies were replaced with irrelevant responses, only the left inferior gyrus activation was common to all subjects. This study presents a systematic strategy for testing the cognitive basis of deception models, and a qualitative approach to single-subject truth-verification fMRI tests. PMID:18569732

  8. Hypnotic depth and response to suggestion under standardized conditions and during FMRI scanning.

    PubMed

    Oakley, David A; Deeley, Quinton; Halligan, Peter W

    2007-01-01

    Hypnosis is a potentially valuable cognitive tool for neuroimaging studies. However, understandable concern that Magnetic Resonance Imaging (MRI) in particular may adversely affect hypnotic procedures remains. Measurements of hypnotic depth and responsiveness to suggestions were taken using a standardized procedure that met all the requirements for functional MRI (fMRI). Testing outside the scanning environment showed reliable and stable changes in subjective hypnotic depth, with no carryover once the hypnosis had been terminated. Within-subject comparisons showed that the magnitude and pattern of these changes and the degree of responsiveness to hypnotic suggestion were not discernibly affected by the fMRI environment. It is concluded that hypnosis can be employed as a discrete and reliable cognitive tool within fMRI neuroimaging settings. PMID:17135062

  9. Realization of magnetic resonance current density imaging at 3 tesla.

    PubMed

    Goksu, C; Sadighi, M; Eroglu, H H; Eyuboglu, M

    2014-08-01

    Magnetic Resonance Current Density Imaging (MRCDI) is an imaging modality, which reconstructs electrical current density distribution inside a material by using Magnetic Resonance Imaging (MRI) techniques. In this study, a current source with maximum current injection capability of 224.7mA, under 1k? resistive load is used. Experiments are performed with a 2D uniform phantom, in which a current steering insulator is inserted. Magnetic flux density distributions are measured, and current density images are reconstructed. The reconstructed images are in agreement with the reconstructions obtained with simulated measurements. PMID:25570158

  10. One-pot synthesis of magnetic nanoclusters enabling atherosclerosis-targeted magnetic resonance imaging

    PubMed Central

    Kukreja, Aastha; Lim, Eun-Kyung; Kang, Byunghoon; Choi, Yuna; Lee, Taeksu; Suh, Jin-Suck; Huh, Yong-Min; Haam, Seungjoo

    2014-01-01

    In this study, dextran-encrusted magnetic nanoclusters (DMNCs) were synthesized using a one-pot solution phase method for detection of atherosclerosis by magnetic resonance imaging. Pyrenyl dextran was used as a surfactant because of its electron-stabilizing effect and its amphiphilic nature, rendering the DMNCs stable and water-dispersible. The DMNCs were 65.6±4.3 nm, had a narrow size distribution, and were superparamagnetic with a high magnetization value of 60.1 emu/g. Further, they showed biocompatibility and high cellular uptake efficiency, as indicated by a strong interaction between dextran and macrophages. In vivo magnetic resonance imaging demonstrated the ability of DMNCs to act as an efficient magnetic resonance imaging contrast agent capable of targeted detection of atherosclerosis. In view of these findings, it is concluded that DMNCs can be used as magnetic resonance imaging contrast agents to detect inflammatory disease. PMID:24904209

  11. MAGNETIC RESONANCE IN CHEMISTRY Magn. Reson. Chem. 2004; 42: 453458

    E-print Network

    Loening, Niko

    & Sons, Ltd. KEYWORDS: NMR; 1 H NMR; 13 C NMR; oligosaccharides; high-resolution magic angle spinning to be useful methods for generating oligopeptides,1,2 oligonucleotides3 and, more recently, oligosaccharides.4 relevant in the analysis of oligosaccharides, where the 1 H resonances are dispersed over a relatively

  12. Lattice Boltzmann Simulations of Pulsed Field Gradient Nuclear Magnetic Resonance

    Microsoft Academic Search

    M. Boudjema; R. A. Guyer; K. R. McCall

    2003-01-01

    Nuclear magnetic resonance (NMR) has become a powerful well-logging tool for understanding pore space geometry of reservoir rocks in-situ. This is because, in many rocks the decay of nuclear magnetization carried by a fluid, (e.g., proton magnetization on H2O molecules) is most strongly influenced by relaxation at the pore walls. We have developed a lattice Boltzmann computational procedure to model

  13. Spin microscope based on optically detected magnetic resonance

    DOEpatents

    Berman, Gennady P. (Los Alamos, NM); Chernobrod, Boris M. (Los Alamos, NM)

    2009-10-27

    The invention relates to scanning magnetic microscope which has a photoluminescent nanoprobe implanted in the tip apex of an atomic force microscope (AFM), a scanning tunneling microscope (STM) or a near-field scanning optical microscope (NSOM) and exhibits optically detected magnetic resonance (ODMR) in the vicinity of unpaired electron spins or nuclear magnetic moments in the sample material. The described spin microscope has demonstrated nanoscale lateral resolution and single spin sensitivity for the AFM and STM embodiments.

  14. Spin microscope based on optically detected magnetic resonance

    DOEpatents

    Berman, Gennady P. (Los Alamos, NM); Chernobrod, Boris M. (Los Alamos, NM)

    2010-07-13

    The invention relates to scanning magnetic microscope which has a photoluminescent nanoprobe implanted in the tip apex of an atomic force microscope (AFM), a scanning tunneling microscope (STM) or a near-field scanning optical microscope (NSOM) and exhibits optically detected magnetic resonance (ODMR) in the vicinity of unpaired electron spins or nuclear magnetic moments in the sample material. The described spin microscope has demonstrated nanoscale lateral resolution and single spin sensitivity for the AFM and STM embodiments.

  15. Spin microscope based on optically detected magnetic resonance

    DOEpatents

    Berman, Gennady P. (Los Alamos, NM); Chernobrod, Boris M. (Los Alamos, NM)

    2010-06-29

    The invention relates to scanning magnetic microscope which has a photoluminescent nanoprobe implanted in the tip apex of an atomic force microscope (AFM), a scanning tunneling microscope (STM) or a near-field scanning optical microscope (NSOM) and exhibits optically detected magnetic resonance (ODMR) in the vicinity of unpaired electron spins or nuclear magnetic moments in the sample material. The described spin microscope has demonstrated nanoscale lateral resolution and single spin sensitivity for the AFM and STM embodiments.

  16. Spin microscope based on optically detected magnetic resonance

    DOEpatents

    Berman, Gennady P. (Los Alamos, NM); Chernobrod, Boris M. (Los Alamos, NM)

    2007-12-11

    The invention relates to scanning magnetic microscope which has a photoluminescent nanoprobe implanted in the tip apex of an atomic force microscope (AFM), a scanning tunneling microscope (STM) or a near-field scanning optical microscope (NSOM) and exhibits optically detected magnetic resonance (ODMR) in the vicinity of unpaired electron spins or nuclear magnetic moments in the sample material. The described spin microscope has demonstrated nanoscale lateral resolution and single spin sensitivity for the AFM and STM embodiments.

  17. Spin microscope based on optically detected magnetic resonance

    DOEpatents

    Berman, Gennady P. (Los Alamos, NM); Chernobrod, Boris M. (Los Alamos, NM)

    2009-11-10

    The invention relates to scanning magnetic microscope which has a photoluminescent nanoprobe implanted in the tip apex of an atomic force microscope (AFM), a scanning tunneling microscope (STM) or a near-field scanning optical microscope (NSOM) and exhibits optically detected magnetic resonance (ODMR) in the vicinity of impaired electron spins or nuclear magnetic moments in the sample material. The described spin microscope has demonstrated nanoscale lateral resolution and single spin sensitivity for the AFM and STM embodiments.

  18. Magnetic Resonance Imaging and Magnetic Resonance Spectroscopy Characterize a Rodent Model of Covert Stroke

    NASA Astrophysics Data System (ADS)

    Herrera, Sheryl Lyn

    Covert stroke (CS) comprises lesions in the brain often associated by risk factors such as a diet high in fat, salt, cholesterol and sugar (HFSCS). Developing a rodent model for CS incorporating these characteristics is useful for developing and testing interventions. The purpose of this thesis was to determine if magnetic resonance (MR) can detect brain abnormalities to confirm this model will have the desired anatomical effects. Ex vivo MR showed brain abnormalities for rats with the induced lesions and fed the HFSCS diet. Spectra acquired on the fixed livers had an average percent area under the fat peak relative to the water peak of (20+/-4)% for HFSCS and (2+/-2)% for control. In vivo MR images had significant differences between surgeries to induce the lesions (p=0.04). These results show that applying MR identified abnormalities in the rat model and therefore is important in the development of this CS rodent model.

  19. Brain Magnetic Resonance Imaging and Magnetic Resonance Spectroscopy Findings of Children with Kernicterus

    PubMed Central

    Sar?, Sahabettin; Yavuz, Alpaslan; Batur, Aabdussamet; Bora, Ayd?n; Caksen, Huseyin

    2015-01-01

    Summary Background The term kernicterus, or bilirubin encephalopathy, is used to describe pathological bilirubin staining of the basal ganglia, brain stem, and cerebellum, and is associated with hyperbilirubinemia. Kernicterus generally occurs in untreated hyperbilirubinemia or cases where treatment is delayed. Magnetic resonance imaging (MRI)-based studies have shown characteristic findings in kernicterus. The objective of our study was to describe the role of 1H magnetic resonance spectroscopy (MRS) in demonstrating these metabolic changes and to review conventional MRI findings of kernicterus. Material/Methods Forty-eight pediatric cases with kernicterus were included in this study. MRI and MRS examinations were performed on variable dates (10–29 days after birth). NAA, Cr, Cho, NAA/Cr, NAA/Cho, and Cho/Cr values were evaluated visually and by computer analysis. Results There was no statistically significant difference between the NAA and Cho levels in the acute kernicterus patients and the control group (healthy patients), whereas both were significantly elevated in the chronic kernicterus patients. Both the mean NAA/Cr and Cho/Cr ratio values were significantly higher in the acute and chronic cases compared to the control group. The NAA/Cho ratio value was statistically lower in the acute cases than in the control group while it was similar in the chronic cases. Conclusions Conventional MR imaging and 1H-MRS are important complementary tools in the diagnostics of neonatal bilirubin encephalopathy. This study provided important information for applying these MR modalities in the evaluation of neonates with bilirubin encephalopathy. PMID:25745520

  20. Reaction time, memory strength, and fMRI activity during memory retrieval: Hippocampus and default network are differentially responsive during recollection and familiarity judgments

    Microsoft Academic Search

    Sarah I. Gimbel; James B. Brewer

    2011-01-01

    Retrieval is often subdivided into recollection and familiarity. Memory strength and reaction time (RT) differ for each, complicating functional magnetic resonance imaging (fMRI) studies of these processes. Recollection leads to greater activity in the hippocampus and default network (DN). Increased DN activity with recollection is thought to reflect self-referential processes, but prior studies have not accounted for varying RT, which

  1. Retinotopic Maps, Spatial Tuning, and Locations of Human Visual Areas in Surface Coordinates Characterized with Multifocal and Blocked fMRI Designs

    Microsoft Academic Search

    Linda Henriksson; Juha Karvonen; Niina Salminen-Vaparanta; Henry Railo; Simo Vanni

    2012-01-01

    The localization of visual areas in the human cortex is typically based on mapping the retinotopic organization with functional magnetic resonance imaging (fMRI). The most common approach is to encode the response phase for a slowly moving visual stimulus and to present the result on an individual's reconstructed cortical surface. The main aims of this study were to develop complementary

  2. The Common Neural Bases Between Sexual Desire and Love: A Multilevel Kernel Density fMRI Analysisjsm_2651 1..7

    E-print Network

    The Common Neural Bases Between Sexual Desire and Love: A Multilevel Kernel Density f and love. As two mental states of intense longing for union with others, sexual desire and love are-analyses of all functional magnetic resonance imaging (fMRI) studies on sexual desire and love. Methods

  3. Neural Responses to Visual Food Stimuli After a Normal vs. Higher Protein Breakfast in Breakfast-Skipping Teens: A Pilot fMRI Study

    Microsoft Academic Search

    Heather J. Leidy; Rebecca J. Lepping; Cary R. Savage; Corey T. Harris

    2011-01-01

    This functional magnetic resonance imaging (fMRI) pilot study identified whether breakfast consumption would alter the neural activity in brain regions associated with food motivation and reward in overweight “breakfast skipping” (BS) adolescent girls and examined whether increased protein at breakfast would lead to additional alterations. Ten girls (Age: 15 ± 1 years; BMI percentile 93 ± 1%; BS 5 ±

  4. Modeling of region-specific fMRI BOLD neurovascular response functions in rat brain reveals residual differences that correlate with the differences in regional evoked potentials

    Microsoft Academic Search

    Christopher P. Pawela; Anthony G. Hudetz; B. Douglas Ward; Marie L. Schulte; Rupeng Li; Dennis S. Kao; Matthew C. Mauck; Younghoon R. Cho; Jay Neitz; James S. Hyde

    2008-01-01

    The response of the rat visual system to flashes of blue light has been studied by blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI). The BOLD temporal response is dependent on the number of flashes presented and demonstrates a refractory period that depends on flash frequency. Activated brain regions included the primary and secondary visual cortex, superior colliculus (SC),

  5. Reading the mind in cartoons and stories: an fMRI study of ‘theory of mind’ in verbal and nonverbal tasks

    Microsoft Academic Search

    H. L. Gallagher; F. Happe; N. Brunswick; P. C. Fletcher; U. Frith; C. D. Frith

    2000-01-01

    Previous functional imaging studies have explored the brain regions activated by tasks requiring ‘theory of mind’—the attribution of mental states. Tasks used have been primarily verbal, and it has been unclear to what extent different results have reflected different tasks, scanning techniques, or genuinely distinct regions of activation. Here we report results from a functional magnetic resonance imaging study (fMRI)

  6. Event-Related Fmri Evidence of Frontotemporal Involvement in Aberrant Response Inhibition and Task Switching in Attention-Deficit/hyperactivity Disorder.

    ERIC Educational Resources Information Center

    Tamm, Leanne; Menon, Vinod; Ringel, Jessica; Reiss, Allan L.

    2004-01-01

    Objective: Response inhibition deficits are characteristic of individuals with attention-deficit/hyperactivity disorder (ADHD). Previous functional magnetic resonance imaging (fMRI) studies investigating the neural correlates of this dysfunction have used block designs, making it difficult to disentangle activation differences specifically related…

  7. Attentional load and sensory competition in human vision: modulation of fMRI responses by load at fixation during task-irrelevant stimulation in the peripheral visual field

    Microsoft Academic Search

    Sophie Schwartz; Patrik Vuilleumier; Chloe Hutton; Angelo Maravita; Raymond J. Dolan; Jon Driver

    2005-01-01

    Perceptual suppression of distractors may depend on both endogenous and exogenous factors, such as attentional load of the current task and sensory competition among simultaneous stimuli, respectively. We used functional magnetic resonance imaging (fMRI) to compare these two types of attentional effects and examine how they may interact in the human brain. We varied the attentional load of a visual

  8. Effect of Observation of Simple Hand Movement on Brain Activations in Patients with Unilateral Cerebral Palsy: An fMRI Study

    ERIC Educational Resources Information Center

    Dinomais, Mickael; Lignon, Gregoire; Chinier, Eva; Richard, Isabelle; Minassian, Aram Ter; The Tich, Sylvie N'Guyen

    2013-01-01

    The aim of this functional magnetic resonance imaging (fMRI) study was to examine and compare brain activation in patients with unilateral cerebral palsy (CP) during observation of simple hand movement performed by the paretic and nonparetic hand. Nineteen patients with clinical unilateral CP (14 male, mean age 14 years, 7-21 years) participated…

  9. Reproducibility of activation in Broca's area during covert generation of single words at high field: A single trial FMRI study at 4 T

    Microsoft Academic Search

    Andrew R. Mayer; Jing Xu; Juliana Paré-Blagoev; Stefan Posse

    2006-01-01

    Although functional magnetic resonance imaging (FMRI) has arguably become the most ubiquitously used imaging modality, questions remain about the reproducibility of the observed patterns of activation and the acquisition time required to achieve statistically significant and reproducible maps. In the current study, we investigated the reliability of activation in Broca's area, on both a voxel-wise and region of interest level,

  10. Defining functional SMA and pre-SMA subregions in human MFC using resting state fMRI: Functional connectivity-based parcellation method

    Microsoft Academic Search

    Jae-Hun Kim; Jong-Min Lee; Hang Joon Jo; Sook Hui Kim; Jung Hee Lee; Sung Tae Kim; Sang Won Seo; Robert W. Cox; Duk L. Na; Sun I. Kim; Ziad S. Saad

    2010-01-01

    Noninvasive parcellation of the human cerebral cortex is an important goal for understanding and examining brain functions. Recently, the patterns of anatomical connections using diffusion tensor imaging (DTI) have been used to parcellate brain regions. Here, we present a noninvasive parcellation approach that uses “functional fingerprints” obtained by correlation measures on resting state functional magnetic resonance imaging (fMRI) data to

  11. Brain Regions Involved in the Retrieval of Spatial and Episodic Details Associated with a Familiar Environment: An fMRI Study

    ERIC Educational Resources Information Center

    Hirshhorn, Marnie; Grady, Cheryl; Rosenbaum, R. Shayna; Winocur, Gordon; Moscovitch, Morris

    2012-01-01

    Functional magnetic resonance imaging (fMRI) was used to compare brain activity during the retrieval of coarse- and fine-grained spatial details and episodic details associated with a familiar environment. Long-time Toronto residents compared pairs of landmarks based on their absolute geographic locations (requiring either coarse or fine…

  12. Raspberry-like metamolecules exhibiting strong magnetic resonances.

    PubMed

    Qian, Zhaoxia; Hastings, Simon P; Li, Chen; Edward, Brian; McGinn, Christine K; Engheta, Nader; Fakhraai, Zahra; Park, So-Jung

    2015-02-24

    We report a synthetic approach to produce raspberry-like plasmonic nanostructures with unusually strong magnetic resonances, termed raspberry-like metamolecules (raspberry-MMs). The synthesis based on the surfactant-assisted templated seed-growth method allows for the simultaneous one-step synthesis and assembly of well-insulated gold nanoparticles. The aromatic surfactant used for the syntheses forms a thin protective layer around the nanoparticles, preventing them from touching each other and making it possible to pack discrete nanoparticles at close distances in a single cluster. The resulting isotropic gold nanoparticle clusters (i.e., raspberry-MMs) exhibit unusually broad extinction spectra in the visible and near-IR region. Finite-difference time-domain (FDTD) modeling showed that the raspberry-MMs support strong magnetic resonances that contribute significantly to the broadband spectra. The strong magnetic scattering was also verified by far-field scattering measurements, which show that in the near-IR region the magnetic dipole resonance can be even stronger than the electric dipole resonance in these raspberry-MMs. Structural parameters such as the size and the number of gold nanoparticles composing raspberry-MMs can be readily tuned in our synthetic method. A series of syntheses with varying structure parameters, along with FDTD modeling and mode analyses of corresponding model structures, showed that the close packing of a large number of metal nanoparticles in raspberry-MMs is responsible for the unusually strong magnetic resonances observed here. PMID:25621502

  13. Neural responses to visual food cues according to weight status: a systematic review of functional magnetic resonance imaging studies.

    PubMed

    Pursey, Kirrilly M; Stanwell, Peter; Callister, Robert J; Brain, Katherine; Collins, Clare E; Burrows, Tracy L

    2014-01-01

    Emerging evidence from recent neuroimaging studies suggests that specific food-related behaviors contribute to the development of obesity. The aim of this review was to report the neural responses to visual food cues, as assessed by functional magnetic resonance imaging (fMRI), in humans of differing weight status. Published studies to 2014 were retrieved and included if they used visual food cues, studied humans >18?years old, reported weight status, and included fMRI outcomes. Sixty studies were identified that investigated the neural responses of healthy weight participants (n?=?26), healthy weight compared to obese participants (n?=?17), and weight-loss interventions (n?=?12). High-calorie food images were used in the majority of studies (n?=?36), however, image selection justification was only provided in 19 studies. Obese individuals had increased activation of reward-related brain areas including the insula and orbitofrontal cortex in response to visual food cues compared to healthy weight individuals, and this was particularly evident in response to energy dense cues. Additionally, obese individuals were more responsive to food images when satiated. Meta-analysis of changes in neural activation post-weight loss revealed small areas of convergence across studies in brain areas related to emotion, memory, and learning, including the cingulate gyrus, lentiform nucleus, and precuneus. Differential activation patterns to visual food cues were observed between obese, healthy weight, and weight-loss populations. Future studies require standardization of nutrition variables and fMRI outcomes to enable more direct comparisons between studies. PMID:25988110

  14. Paradigm free mapping with sparse regression automatically detects single-trial functional magnetic resonance imaging blood oxygenation level dependent responses.

    PubMed

    Caballero Gaudes, César; Petridou, Natalia; Francis, Susan T; Dryden, Ian L; Gowland, Penny A

    2013-03-01

    The ability to detect single trial responses in functional magnetic resonance imaging (fMRI) studies is essential, particularly if investigating learning or adaptation processes or unpredictable events. We recently introduced paradigm free mapping (PFM), an analysis method that detects single trial blood oxygenation level dependent (BOLD) responses without specifying prior information on the timing of the events. PFM is based on the deconvolution of the fMRI signal using a linear hemodynamic convolution model. Our previous PFM method (Caballero-Gaudes et al., 2011: Hum Brain Mapp) used the ridge regression estimator for signal deconvolution and required a baseline signal period for statistical inference. In this work, we investigate the application of sparse regression techniques in PFM. In particular, a novel PFM approach is developed using the Dantzig selector estimator, solved via an efficient homotopy procedure, along with statistical model selection criteria. Simulation results demonstrated that, using the Bayesian information criterion to select the regularization parameter, this method obtains high detection rates of the BOLD responses, comparable with a model-based analysis, but requiring no information on the timing of the events and being robust against hemodynamic response function variability. The practical operation of this sparse PFM method was assessed with single-trial fMRI data acquired at 7T, where it automatically detected all task-related events, and was an improvement on our previous PFM method, as it does not require the definition of a baseline state and amplitude thresholding and does not compromise on specificity and sensitivity. PMID:22121048

  15. Neural Responses to Visual Food Cues According to Weight Status: A Systematic Review of Functional Magnetic Resonance Imaging Studies

    PubMed Central

    Pursey, Kirrilly M.; Stanwell, Peter; Callister, Robert J.; Brain, Katherine; Collins, Clare E.; Burrows, Tracy L.

    2014-01-01

    Emerging evidence from recent neuroimaging studies suggests that specific food-related behaviors contribute to the development of obesity. The aim of this review was to report the neural responses to visual food cues, as assessed by functional magnetic resonance imaging (fMRI), in humans of differing weight status. Published studies to 2014 were retrieved and included if they used visual food cues, studied humans >18?years old, reported weight status, and included fMRI outcomes. Sixty studies were identified that investigated the neural responses of healthy weight participants (n?=?26), healthy weight compared to obese participants (n?=?17), and weight-loss interventions (n?=?12). High-calorie food images were used in the majority of studies (n?=?36), however, image selection justification was only provided in 19 studies. Obese individuals had increased activation of reward-related brain areas including the insula and orbitofrontal cortex in response to visual food cues compared to healthy weight individuals, and this was particularly evident in response to energy dense cues. Additionally, obese individuals were more responsive to food images when satiated. Meta-analysis of changes in neural activation post-weight loss revealed small areas of convergence across studies in brain areas related to emotion, memory, and learning, including the cingulate gyrus, lentiform nucleus, and precuneus. Differential activation patterns to visual food cues were observed between obese, healthy weight, and weight-loss populations. Future studies require standardization of nutrition variables and fMRI outcomes to enable more direct comparisons between studies. PMID:25988110

  16. Magnetic resonance imaging with an optical atomic magnetometer.

    PubMed

    Xu, Shoujun; Yashchuk, Valeriy V; Donaldson, Marcus H; Rochester, Simon M; Budker, Dmitry; Pines, Alexander

    2006-08-22

    We report an approach for the detection of magnetic resonance imaging without superconducting magnets and cryogenics: optical atomic magnetometry. This technique possesses a high sensitivity independent of the strength of the static magnetic field, extending the applicability of magnetic resonance imaging to low magnetic fields and eliminating imaging artifacts associated with high fields. By coupling with a remote-detection scheme, thereby improving the filling factor of the sample, we obtained time-resolved flow images of water with a temporal resolution of 0.1 s and spatial resolutions of 1.6 mm perpendicular to the flow and 4.5 mm along the flow. Potentially inexpensive, compact, and mobile, our technique provides a viable alternative for MRI detection with substantially enhanced sensitivity and time resolution for various situations where traditional MRI is not optimal. PMID:16885210

  17. Magnetic resonance imaging with an optical atomic magnetometer

    PubMed Central

    Xu, Shoujun; Yashchuk, Valeriy V.; Donaldson, Marcus H.; Rochester, Simon M.; Budker, Dmitry; Pines, Alexander

    2006-01-01

    We report an approach for the detection of magnetic resonance imaging without superconducting magnets and cryogenics: optical atomic magnetometry. This technique possesses a high sensitivity independent of the strength of the static magnetic field, extending the applicability of magnetic resonance imaging to low magnetic fields and eliminating imaging artifacts associated with high fields. By coupling with a remote-detection scheme, thereby improving the filling factor of the sample, we obtained time-resolved flow images of water with a temporal resolution of 0.1 s and spatial resolutions of 1.6 mm perpendicular to the flow and 4.5 mm along the flow. Potentially inexpensive, compact, and mobile, our technique provides a viable alternative for MRI detection with substantially enhanced sensitivity and time resolution for various situations where traditional MRI is not optimal. PMID:16885210

  18. Ion resonance cones in a magnetized plasma

    NASA Astrophysics Data System (ADS)

    Riccardi, C.; Salierno, M.; Cantù, P.; Fontanesi, M.

    1996-05-01

    An experimental and theoretical study on ion resonance cones has been carried out taking into account both thermal and source effects. The measurements have been performed in a small toroidal device, with different antenna systems to excite the waves.

  19. Ferromagnetic resonance imaging of Co films using magnetic resonance force microscopy

    SciTech Connect

    Suh, B.J.; Hammel, P.C.; Zhang, Z. [Condensed Matter and Thermal Physics, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Condensed Matter and Thermal Physics, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Midzor, M.M.; Roukes, M.L. [Condensed Matter Physics, California Institute of Technology, Pasadena, California 91125 (United States)] [Condensed Matter Physics, California Institute of Technology, Pasadena, California 91125 (United States); Childress, J.R. [University of Florida, Gainesville, Florida 32611 (United States)] [University of Florida, Gainesville, Florida 32611 (United States)

    1998-07-01

    Lateral one-dimensional imaging of cobalt (Co) films by means of microscopic ferromagnetic resonance (FMR) detected using the magnetic resonance force microscope (MRFM) is demonstrated. A novel approach involving scanning a localized magnetic probe is shown to enable FMR imaging in spite of the broad resonance linewidth. We introduce a spatially selective local field by means of a small, magnetically polarized spherical crystallite of yttrium iron garnet (YIG). Using MRFM-detected FMR signals from a sample consisting of two Co films, we can resolve the {approximately}20 {mu}m lateral separation between the films. The results can be qualitatively understood by consideration of the calculated spatial profiles of the magnetic field generated by the YIG sphere. {copyright} {ital 1998 American Vacuum Society.}

  20. How Good Is Good Enough in Path Analysis of fMRI Data?

    Microsoft Academic Search

    Ed Bullmore; Barry Horwitz; Garry Honey; Mick Brammer; Steve Williams; Tonmoy Sharma

    2000-01-01

    This paper is concerned with the problem of evaluating goodness-of-fit of a path analytic model to an interregional correlation matrix derived from functional magnetic resonance imaging (fMRI) data. We argue that model evaluation based on testing the null hypothesis that the correlation matrix predicted by the model equals the population correlation matrix is problematic because P values are conditional on

  1. Independent component analysis for brain FMRI does indeed select for maximal independence.

    PubMed

    Calhoun, Vince D; Potluru, Vamsi K; Phlypo, Ronald; Silva, Rogers F; Pearlmutter, Barak A; Caprihan, Arvind; Plis, Sergey M; Adal?, Tülay

    2013-01-01

    A recent paper by Daubechies et al. claims that two independent component analysis (ICA) algorithms, Infomax and FastICA, which are widely used for functional magnetic resonance imaging (fMRI) analysis, select for sparsity rather than independence. The argument was supported by a series of experiments on synthetic data. We show that these experiments fall short of proving this claim and that the ICA algorithms are indeed doing what they are designed to do: identify maximally independent sources. PMID:24009746

  2. The anterior cingulate as a conflict monitor: fMRI and ERP studies

    Microsoft Academic Search

    Vincent van Veen; Cameron S. Carter

    2002-01-01

    We propose that the anterior cingulate cortex (ACC) contributes to cognition by detecting the presence of conflict during information processing, and to alert systems involved in top-down control to resolve this conflict. Here, we review several functional magnetic resonance imaging (fMRI) and event-related potential (ERP) studies that have used simple response interference tasks, and propose that ACC activity is activated

  3. Incidental effects of emotional valence in single word processing: An fMRI study

    Microsoft Academic Search

    Lars Kuchinke; Arthur M. Jacobs; Claudia Grubich; Melissa L.-H. Võ; Markus Conrad; Manfred Herrmann

    2005-01-01

    The present study aimed at identifying the neural responses associated with the incidental processing of the emotional valence of single words using event-related functional magnetic resonance imaging (fMRI). Twenty right-handed participants performed a visual lexical decision task, discriminating between nouns and orthographically and phonologically legal nonwords. Positive, neutral and negative word categories were matched for frequency, number and frequency of

  4. Alcohol Intoxication Effects on Visual Perception: An fMRI Study

    Microsoft Academic Search

    V. D. Calhoun; D. Altschul; V. McGinty; R. Shih; D. Scott; G. D. Pearlson

    2004-01-01

    We examined the effects of two doses of alcohol (EtOH) on functional magnetic resonance imaging (fMRI) activation during a visual perception task. The Motor-Free Visual Perception Test-Revised (MVPT-R) provides measures of overall visual perceptual processing ability. It incorporates different cognitive elements including visual discrimination, spatial relationships, and mental rotation. We used the MVPT-R to study brain activation patterns in healthy

  5. DWT-CEM: an algorithm for scale-temporal clustering in fMRI

    Microsoft Academic Search

    João Ricardo Sato; André Fujita; Edson Amaro Jr.; Janaina Mourão Miranda; Pedro Alberto Morettin; Michal John Brammer

    2007-01-01

    The number of studies using functional magnetic resonance imaging (fMRI) has grown very rapidly since the first description\\u000a of the technique in the early 1990s. Most published studies have utilized data analysis methods based on voxel-wise application\\u000a of general linear models (GLM). On the other hand, temporal clustering analysis (TCA) focuses on the identification of relationships\\u000a between cortical areas by

  6. BOLD fMRI activation induced by vagus nerve stimulation in seizure patients

    Microsoft Academic Search

    W-C Liu; K Mosier; A J Kalnin; D Marks

    2003-01-01

    Objective: To identify the cerebral activated regions associated with the vagus nerve stimulation in epilepsy patients.Design: Blood oxygenation level dependent functional magnetic resonance imaging (BOLD fMRI) was employed to detect areas of the brain activated by vagus nerve stimulation in five patients with documented complex partial seizures.Methods: Functional MRI was done on a GE 1.5T Echospeed horizon scanner. Before each

  7. Resting state fMRI in Alzheimer's disease: beyond the default mode network

    Microsoft Academic Search

    Federica Agosta; Michela Pievani; Cristina Geroldi; Massimiliano Copetti; Giovanni B. Frisoni; Massimo Filippi

    Using resting state (RS) functional magnetic resonance imaging (fMRI), the connectivity patterns of the default mode (DMN), frontoparietal, executive, and salience networks were explored in 13 Alzheimer's disease (AD) patients, 12 amnestic mild cognitive impairment (aMCI) patients, and 13 healthy controls. Compared with controls and aMCI, AD was associated with opposing connectivity effects in the DMN (decreased) and frontal networks

  8. fMRI BOLD Signal Changes in Elite Swimmers While Viewing Videos of Personal Failure

    Microsoft Academic Search

    Henry Davis IV; Mario Liotti; Elton T. Ngan; Todd S. Woodward; Jared X. Van Snellenberg; Sari M. van Anders; Aynsley Smith; Helen S. Mayberg

    2008-01-01

    Athletes who fail are susceptible to negative affect (NA) and impaired future performance. Functional magnetic resonance imaging\\u000a (fMRI) studies have identified prefrontal, anterior cingulate, and limbic activations following negative mood provocation.\\u000a Little is known about the neural correlates of negative self-reference (SR), especially in athletes. Even less is known about\\u000a the neural correlates of the effects of cognitive intervention (CI)

  9. Pooling fMRI data: meta-analysis, mega-analysis and multi-center studies

    Microsoft Academic Search

    Sergi G. Costafreda; Craig M. Bennet; Russell A. Poldrack

    2009-01-01

    The quantitative analysis of pooled data from related functional magnetic resonance imaging (fMRI) experiments has the potential to signifi cantly accelerate progress in brain mapping. Such data-pooling can be achieved through meta-analysis (the pooled analysis of published results), mega-analysis (the pooled analysis of raw data) or multi-site studies, which can be seen as designed mega-analyses. Current limitations in function-location brain

  10. fMRI tracks reductions in repetitive behaviors in autism: Two case studies

    Microsoft Academic Search

    Gabriel S. Dichter; Linmarie Sikich; Steve Mahorney; Jennifer N. Felder; Kristen S. L. Lam; Lauren Turner-Brown; James Bodfish

    2010-01-01

    Autism is characterized by abnormal prefrontal brain activation during cognitive control, a potential biomarker of repetitive behaviors. In this proof-of-principle study, functional magnetic resonance imaging (fMRI) was used to examine brain activity during an oddball task in two high-functioning males with autism before and after 12 weeks of treatment with citalopram, a selective serotonin reuptake inhibitor. One participant showed marked

  11. An fMRI study of optokinetic nystagmus and smooth-pursuit eye movements in humans

    Microsoft Academic Search

    Christina S. Konen; Raimund Kleiser; Rüdiger J. Seitz; Frank Bremmer

    2005-01-01

    Both optokinetic nystagmus (OKN) and smooth-pursuit eye movements (SPEM) are subclasses of so-called slow eye movements. However, optokinetic responses are reflexive whereas smooth pursuit requires the voluntary tracking of a moving target. We used functional magnetic resonance imaging (fMRI) to determine the neural basis of OKN and SPEM, and to uncover whether the two underlying neural systems overlap or are

  12. Increased Cortical Activity in Binge Drinkers during Working Memory Task: A Preliminary Assessment through a Functional Magnetic Resonance Imaging Study

    PubMed Central

    Campanella, Salvatore; Peigneux, Philippe; Petit, Géraldine; Lallemand, Frédéric; Saeremans, Mélanie; Noël, Xavier; Metens, Thierry; Nouali, Mustapha; De Tiège, Xavier; De Witte, Philippe; Ward, Roberta; Verbanck, Paul

    2013-01-01

    Background Cerebral dysfunction is a common feature of both chronic alcohol abusers and binge drinkers. Here, we aimed to study whether, at equated behavioral performance levels, binge drinkers exhibited increased neural activity while performing simple cognitive tasks. Methods Thirty-two participants (16 binge drinkers and 16 matched controls) were scanned using functional magnetic resonance imaging (fMRI) while performing an n-back working memory task. In the control zero-back (N0) condition, subjects were required to press a button with the right hand when the number “2? was displayed. In the two-back (N2) condition, subjects had to press a button when the displayed number was identical to the number shown two trials before. Results fMRI analyses revealed higher bilateral activity in the pre-supplementary motor area in binge drinkers than matched controls, even though behavioral performances were similar. Moreover, binge drinkers showed specific positive correlations between the number of alcohol doses consumed per occasion and higher activity in the dorsomedial prefrontal cortex, as well as between the number of drinking occasions per week and higher activity in cerebellum, thalamus and insula while performing the N2 memory task. Conclusions Binge alcohol consumption leads to possible compensatory cerebral changes in binge drinkers that facilitate normal behavioral performance. These changes in cerebral responses may be considered as vulnerability factors for developing adult substance use disorders. PMID:23638017

  13. Functional magnetic resonance imaging assessment of the human brain auditory cortex response to increasing word presentation rates.

    PubMed

    Dhankhar, A; Wexler, B E; Fulbright, R K; Halwes, T; Blamire, A M; Shulman, R G

    1997-01-01

    In an investigation of the auditory cortex response to speech, six subjects were studied using echo-planar functional magnetic resonance imaging (fMRI) at 2.1T. The subjects were asked to listen to English nouns presented at various rates ranging from 0 words per minute (wpm) to 130 wpm while fMRI images encompassing their primary and posterior superior secondary auditory cortices were acquired. An asymmetric spin echo imaging sequence was used with an induced T2 weighting of 50 ms to allow for transverse relaxation effects. Images were acquired in two or four axial-oblique slices with a repetition time of 3.75 or 7.5 s, in plane resolution of 6 x 3 mm, and a slice thickness of 5 mm. Localized activation centered over grey matter was consistently observed in all subjects in the transverse temporal gyrus (TTG), the transverse temporal sulcus (TTS), and the posterior superior aspect of the superior temporal gyrus (STG). The total activate volume and the integrated signal response in bilateral primary and posterior superior secondary auditory cortices increased with increasing rate of word presentation, peaking at 90 wpm (with some intersubject variability) with a subsequent fall at 130 wpm. There were no significant differences in the rate dependence of the signal response in bilateral primary and bilateral posterior superior secondary auditory cortices (P < 0.05). PMID:9120588

  14. The prefrontal dysfunction in individuals with Internet gaming disorder: a meta-analysis of functional magnetic resonance imaging studies.

    PubMed

    Meng, Yajing; Deng, Wei; Wang, Huiyao; Guo, Wanjun; Li, Tao

    2015-07-01

    With the advancement in high-resolution magnetic resonance imaging (MRI) technology and automated analysis, studies on functional MRI (fMRI) made it possible to identify the functional activity of brain in vivo in individuals with Internet gaming disorder (IGD), and to explore the underpinning neuroscience basis of IGD. Yet, no available literature has systemically reviewed the fMRI studies of IGD using meta-analyses. This study reviewed 61 candidate articles and finally selected 10 qualified voxel-wise whole-brain analysis studies for performing a comprehensive series of meta-analyses employing effect size signed differential mapping approach. Compared with healthy controls, subjects with IGD showed a significant activation in the bilateral medial frontal gyrus (MFG) and the left cingulate gyrus, as well as the left medial temporal gyrus and fusiform gyrus. Furthermore, the on-line time of IGD subjects was positively correlated with activations in the left MFG and the right cingulated gyrus. These findings implicate the important role of dysfunctional prefrontal lobe in the neuropathological mechanism of IGD. Considering the overlapped role of prefrontal lobe in the reward and self-regulatory system, our results provided supportive evidence for the reclassification of IGD as a behavioural addiction. PMID:24889021

  15. SUBJECT SCREENING FORM Functional Magnetic Resonance Imaging (fMRI) of Human Sensory Systems

    E-print Network

    Talavage, Thomas M.

    surgery 10. frequent migraine headaches 11. currently taking medication 12. allergies to either food or drink 13. non-food allergies 14. claustrophobia 15. used illegal drugs at least once 16. glasses M. Talavage, Ph.D. Purdue University School of Electrical and Computer Engineering Weldon School

  16. Nuclear magnetic resonances in weak fields

    E-print Network

    Mitchell, Richard Warren

    1953-01-01

    ?s technique involves ~ su41ng a molecular beam through tuo sueeessive static magnetic fields shish have gradients in opposite direotions, While passing from ene magnetic field ts tho other~ the beam is irradiated eith electro-mag- nstio ?nsrgy? When tho...Lgneto The ssmple was placed in, the best pert of the field Then a permanent magnet was brought close to the solenoid& snd pointed to a spot gust beyond the sample in such a manner that, the field of the permanent magnet was roughly opposibx to that...

  17. Magnetic anisotropy of polycrystalline magnetoferritin investigated by SQUID and electron magnetic resonance

    NASA Astrophysics Data System (ADS)

    Moro, F.; de Miguel, R.; Jenkins, M.; Gómez-Moreno, C.; Sells, D.; Tuna, F.; McInnes, E. J. L.; Lostao, A.; Luis, F.; van Slageren, J.

    2014-06-01

    Magnetoferritin molecules with an average inorganic core diameter of 5.7±1.6 nm and polycrystalline internal structure were investigated by a combination of transmission electron microscopy, magnetic susceptibility, magnetization, and electron magnetic resonance (EMR) experiments. The temperature and frequency dependence of the magnetic susceptibility allowed for the determination of the magnetic anisotropy on an experimental time scale which spans from seconds to nanoseconds. In addition, angle-dependent EMR experiments were carried out for the determination of the nanoparticle symmetry and internal magnetic field. Due to the large surface to volume ratio, the nanoparticles show larger and uniaxial rather than cubic magnetic anisotropies compared to bulk maghemite and magnetite.

  18. Resonant Landau–Zener transitions in a helical magnetic field

    NASA Astrophysics Data System (ADS)

    Wójcik, P.; Adamowski, J.; Wo?oszyn, M.; Spisak, B. J.

    2015-06-01

    Spin-dependent electron transport has been studied in magnetic semiconductor waveguides (nanowires) in the helical magnetic field. We have shown that—apart from the well-known conductance dip located at the magnetic field equal to the helical-field amplitude Bh—the additional conductance dips (with zero conductance) appear at a magnetic field different from Bh. This effect occurring in the non-adiabatic regime is explained as resulting from the resonant Landau–Zener transitions between the spin-split subbands.

  19. Silicon Nanoparticles as Hyperpolarized Magnetic Resonance Imaging Agents

    PubMed Central

    Aptekar, Jacob W.; Cassidy, Maja C.; Johnson, Alexander C.; Barton, Robert A.; Lee, Menyoung; Ogier, Alexander C.; Vo, Chinh; Anahtar, Melis N.; Ren, Yin; Bhatia, Sangeeta N.; Ramanathan, Chandrasekhar; Cory, David G.; Hill, Alison L.; Mair, Ross W.; Rosen, Matthew S.; Walsworth, Ronald L.

    2014-01-01

    Magnetic resonance imaging of hyperpolarized nuclei provides high image contrast with little or no background signal. To date, in-vivo applications of pre-hyperpolarized materials have been limited by relatively short nuclear spin relaxation times. Here, we investigate silicon nanoparticles as a new type of hyperpolarized magnetic resonance imaging agent. Nuclear spin relaxation times for a variety of Si nanoparticles are found to be remarkably long, ranging from many minutes to hours at room temperature, allowing hyperpolarized nanoparticles to be transported, administered, and imaged on practical time scales. Additionally, we demonstrate that Si nanoparticles can be surface functionalized using techniques common to other biologically targeted nanoparticle systems. These results suggest that Si nanoparticles can be used as a targetable, hyperpolarized magnetic resonance imaging agent with a large range of potential applications. PMID:19950973

  20. Pyridoxine-dependent seizures: magnetic resonance spectroscopy findings.

    PubMed

    Alkan, Alpay; Kutlu, Ramazan; Aslan, Mehmet; Sigirci, Ahmet; Orkan, Ismet; Yakinci, Cengiz

    2004-01-01

    Pyridoxine-dependent seizures are an extremely rare genetic disorder. Early diagnosis and treatment are important for the prevention of permanent brain damage. Elevated levels of glutamate and decreased levels of gamma-aminobutyric acid (GABA) in the frontal and parietal cortices are among the characteristic features of this disorder. These metabolic abnormalities eventually lead to seizures and neuronal loss. In this case report, we present magnetic resonance spectroscopy findings of a 9-year-old girl with pyridoxine-dependent seizures with mental retardation. The N-acetylaspartate-to-creatine ratio was found to be decreased in the frontal and parieto-occipital cortices, which could indicate neuronal loss. Magnetic resonance spectroscopy could be a useful tool in the neuroimaging evaluation for assessment of parenchymal changes despite a normal-appearing brain magnetic resonance image in patients with pyridoxine-dependent seizures. PMID:15032392