Sample records for magnetic resonance fmri

  1. Functional magnetic resonance imaging (FMRI) of the human brain

    Microsoft Academic Search

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

    1994-01-01

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

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

    PubMed Central

    Buxton, Richard B

    2015-01-01

    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. PMID:24006360

  3. 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.

  4. Functional magnetic resonance imaging (fMRI) and positron emission tomography measure local changes in brain

    E-print Network

    Udgaonkar, Jayant B.

    202 Functional magnetic resonance imaging (fMRI) and positron emission tomography measure local underlying the different signal modalities. Address Massachusetts General Hospital Nuclear Magnetic Resonance dipole EEG electroencephalography ERP event-related potential fMRI functional magnetic resonance imaging

  5. Magnetic Resonance Imaging Techniques: fMRI, DWI, and PWI

    PubMed Central

    Holdsworth, Samantha J.; Bammer, Roland

    2012-01-01

    Magnetic resonance imaging (MRI) is a noninvasive technique which can acquire important quantitative and anatomical information from an individual in any plane or volume at comparatively high resolution. Over the past several years, developments in scanner hardware and software have enabled the acquisition of fast MRI imaging, proving extremely useful in various clinical and research applications such as in brain mapping or functional MRI (fMRI), perfusion-weighted imaging (PWI), and diffusion-weighted imaging (DWI). These techniques have revolutionized the use of MRI in the clinics, providing great insight into physiologic mechanisms and pathologic conditions. Since these relatively new areas of MRI have relied on fast scanning techniques, they have only recently been widely introduced to clinical sites. As such, this review article is devoted to the technological aspects of these techniques, as well as their roles and limitations in neuroimaging applications. PMID:18843569

  6. nAture methods | VOL.9 NO.6 | JUNE2012 | 597 Functional magnetic resonance imaging (fmri) based on

    E-print Network

    Articles nAture methods | VOL.9 NO.6 | JUNE2012 | 597 Functional magnetic resonance imaging (fmri relationship to underlying neural activity remains elusive. here, we combined fmri with fiber-optic recordings components. our findings highlight the complexity of fmri Bold signals, involving both neuronal and glial

  7. Magnetic resonance spectroscopy imaging (MRSI) and brain functional magnetic resonance imaging (fMRI) for radiotherapy treatment planning of glioma.

    PubMed

    Chang, Jenghwa; Thakur, Sunitha B; Huang, Wei; Narayana, Ashwatha

    2008-10-01

    Conventional radiotherapy of glioma is ineffective due to uncertainties in target delineation, inadequate radiation dose, and difficulties in identifying radio-resistant high-grade tumor for dose escalation. Magnetic resonance spectroscopy imaging (MRSI) and functional magnetic resonance imaging (fMRI) provide information on altered metabolic activity of tumor cells and functionally critical brain tissues, which are not available from anatomical imaging. In this paper, we review the pathological and physiological information that might be derived from MRSI and fMRI to better delineate the treatment volume and critical organs for glioma radiotherapy. Technical difficulties for incorporating MRSI and fMRI into radiotherapy treatment planning process are discussed and potential solutions are presented. A fusion protocol is used to illustrate the feasibility of registering MRSI and fMRI with simulation CT for one glioma case. An IMRT (intensity-modulated radiotherapy) dose painting plan for this case is also presented using the fused MRSI and fMRI to delineate the clinical target volumes and Broca's area. PMID:18783284

  8. A method of using functional magnetic resonance imaging (fMRI) to measure retinotopic organization within human cortex is described.

    E-print Network

    Wandell, Brian A.

    organization of human cortical area V1 and identified the locations of other nearby retinotopically organized visual areas. We also used the retinotopic organization of human primary visual cortex to measureA method of using functional magnetic resonance imaging (fMRI) to measure retinotopic organization

  9. Face perception, recognition and priming were examined with event-related functional magnetic resonance imaging (fMRI) and

    E-print Network

    Henson, Rik

    Face perception, recognition and priming were examined with event-related functional magnetic resonance imaging (fMRI) and scalp event-related potentials (ERPs). Face perception was asso- ciated, and a right posterior negativity (N170), most likely generated in the superior temporal region. Face

  10. Translational neuroscience and potential contributions of functional magnetic resonance imaging (FMRI) to the prevention of substance misuse and antisocial behavior.

    PubMed

    Whitten, Lori A

    2013-06-01

    The interdisciplinary field of neuroscience has greatly advanced our understanding of the brain and neurobehavioral disorders. Translational neuroscience endeavors to use this knowledge to develop solutions to practical problems: for example, to improve treatment and preventive interventions for neurobehavioral disorders. Although functional magnetic resonance imaging (fMRI) has the potential to contribute to the diagnosis and treatment of psychiatric disorders, efforts to prevent the problems of substance misuse and antisocial behavior have been slow to incorporate neuroscience principles and neuroimaging techniques. The current article summarizes fMRI research on substance misuse and antisocial behavior, highlights its implications for intervention, and explores new ways in which the technique could contribute to prevention efforts. PMID:23404663

  11. The functional magnetic resonance imaging (fMRI) procedure as experienced by healthy participants and stroke patients – A pilot study

    PubMed Central

    2009-01-01

    Background An important aspect in functional imaging research employing magnetic resonance imaging (MRI) is how participants perceive the MRI scanning itself. For instance, the knowledge of how (un)comfortable MRI scanning is perceived may help institutional review boards (IRBs) or ethics committees to decide on the approval of a study, or researchers to design their experiments. Methods We provide empirical data from our lab gained from 70 neurologically healthy mainly student subjects and from 22 mainly elderly patients suffering from motor deficits after brain damage. All participants took part in various basic research fMRI studies using a 3T MRI scanner. Directly after the scanning, all participants completed a questionnaire assessing their experience with the fMRI procedure. Results 87.2% of the healthy subjects and 77.3% of the patients rated the MRI procedure as acceptable to comfortable. In healthy subjects, males found the procedure more comfortable, while the opposite was true for patients. 12.1% of healthy subjects considered scanning durations between 30 and 60 min as too long, while no patient considered their 30 min scanning interval as too long. 93.4% of the healthy subjects would like to participate in an fMRI study again, with a significantly lower rate for the subjects who considered the scanning as too long. Further factors, such as inclusion of a diffusion tensor imaging (DTI) scan, age, and study duration had no effect on the questionnaire responses. Of the few negative comments, the main issues were noise, the restriction to keep still for the whole time, and occasional feelings of dizziness. Conclusion MRI scanning in the basic research setting is an acceptable procedure for elderly and patient participants as well as young healthy subjects. PMID:19646238

  12. 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

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

    PubMed Central

    Murnane, Kevin Sean; Howell, Leonard Lee

    2010-01-01

    Functional magnetic resonance imaging (fMRI) is a technique with significant potential to advance our understanding of multiple brain systems. However, when human subjects undergo fMRI studies they are typically conscious whereas pre-clinical fMRI studies typically utilize anesthesia, which complicates comparisons across studies. Therefore, we have developed an apparatus suitable for imaging conscious rhesus monkeys. In order to minimize subject stress and spatial motion, each subject was acclimated to the necessary procedures over several months. The effectiveness of this process was then evaluated, in fully trained subjects, by quantifying objective physiological measures. These physiological metrics were stable both within and across sessions and did not differ from when these same subjects were immobilized using standard primate handling procedures. Subject motion and blood oxygenation level dependent (BOLD) fMRI measurements were then evaluated by scanning subjects under three different conditions: the absence of stimulation, presentation of a visual stimulus, or administration of intravenous (i.v.) cocaine (0.3 mg/kg). Spatial motion differed neither by condition nor along the three principal axes. In addition, maximum translational and rotational motion never exceeded one half of the voxel size (0.75 mm) or 1.5 degrees, respectively. Furthermore, the localization of changes in blood oxygenation closely matched those reported in previous studies using similar stimuli. These findings document the feasibility of fMRI data collection in conscious rhesus monkeys using these procedures and allow for the further study of the neural effects of psychoactive drugs. PMID:20566353

  14. Relation between functional magnetic resonance imaging (fMRI) and single neuron, local field potential (LFP) and electrocorticography (ECoG) activity in human cortex

    PubMed Central

    Ojemann, George A.; Ramsey, Nick F.; Ojemann, Jeffrey

    2013-01-01

    The relation between changes in the blood oxygen dependent metabolic changes imaged by functional magnetic resonance imaging (fMRI) and neural events directly recorded from human cortex from single neurons, local field potentials (LFPs) and electrocorticogram (ECoG) is critically reviewed, based on the published literature including findings from the authors' laboratories. All these data are from special populations, usually patients with medically refractory epilepsy, as this provides the major opportunity for direct cortical neuronal recording in humans. For LFP and ECoG changes are often sought in different frequency bands, for single neurons in frequency of action potentials. Most fMRI studies address issues of functional localization. The relation of those findings to localized changes in neuronal recordings in humans has been established in several ways. Only a few studies have directly compared changes in activity from the same sites in the same individual, using the same behavioral measure. More often the comparison has been between fMRI and electrophysiologic changes in populations recorded from the same functional anatomic system as defined by lesion effects; in a few studies those systems have been defined by fMRI changes such as the “default” network. The fMRI-electrophysiologic relationships have been evaluated empirically by colocalization of significant changes, and by quantitative analyses, often multiple linear regression. There is some evidence that the fMRI-electrophysiology relationships differ in different cortical areas, particularly primary motor and sensory cortices compared to association cortex, but also within areas of association cortex. Although crucial for interpretation of fMRI changes as reflecting neural activity in human cortex, controversy remains as to these relationships. Supported by: Dutch Technology Foundation and University of Utrecht Grant UGT7685, ERC-Advanced grant 320708 (NR) and NIH grant NS065186 (JO) PMID:23431088

  15. Functional magnetic resonance imaging (fMRI) “brain reading”: detecting and classifying distributed patterns of fMRI activity in human visual cortex

    Microsoft Academic Search

    David D. Cox; Robert L. Savoy

    2003-01-01

    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

  16. Functional Magnetic Resonance Imaging

    ERIC Educational Resources Information Center

    Voos, Avery; Pelphrey, Kevin

    2013-01-01

    Functional magnetic resonance imaging (fMRI), with its excellent spatial resolution and ability to visualize networks of neuroanatomical structures involved in complex information processing, has become the dominant technique for the study of brain function and its development. The accessibility of in-vivo pediatric brain-imaging techniques…

  17. Iterative approach of dual regression with a sparse prior enhances the performance of independent component analysis for group functional magnetic resonance imaging (fMRI) data.

    PubMed

    Kim, Yong-Hwan; Kim, Junghoe; Lee, Jong-Hwan

    2012-12-01

    This study proposes an iterative dual-regression (DR) approach with sparse prior regularization to better estimate an individual's neuronal activation using the results of an independent component analysis (ICA) method applied to a temporally concatenated group of functional magnetic resonance imaging (fMRI) data (i.e., Tc-GICA method). An ordinary DR approach estimates the spatial patterns (SPs) of neuronal activation and corresponding time courses (TCs) specific to each individual's fMRI data with two steps involving least-squares (LS) solutions. Our proposed approach employs iterative LS solutions to refine both the individual SPs and TCs with an additional a priori assumption of sparseness in the SPs (i.e., minimally overlapping SPs) based on L(1)-norm minimization. To quantitatively evaluate the performance of this approach, semi-artificial fMRI data were created from resting-state fMRI data with the following considerations: (1) an artificially designed spatial layout of neuronal activation patterns with varying overlap sizes across subjects and (2) a BOLD time series (TS) with variable parameters such as onset time, duration, and maximum BOLD levels. To systematically control the spatial layout variability of neuronal activation patterns across the "subjects" (n=12), the degree of spatial overlap across all subjects was varied from a minimum of 1 voxel (i.e., 0.5-voxel cubic radius) to a maximum of 81 voxels (i.e., 2.5-voxel radius) across the task-related SPs with a size of 100 voxels for both the block-based and event-related task paradigms. In addition, several levels of maximum percentage BOLD intensity (i.e., 0.5, 1.0, 2.0, and 3.0%) were used for each degree of spatial overlap size. From the results, the estimated individual SPs of neuronal activation obtained from the proposed iterative DR approach with a sparse prior showed an enhanced true positive rate and reduced false positive rate compared to the ordinary DR approach. The estimated TCs of the task-related SPs from our proposed approach showed greater temporal correlation coefficients with a reference hemodynamic response function than those of the ordinary DR approach. Moreover, the efficacy of the proposed DR approach was also successfully demonstrated by the results of real fMRI data acquired from left-/right-hand clenching tasks in both block-based and event-related task paradigms. PMID:22939873

  18. 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 ...

  19. Medial temporal lobe activation during context-dependent relational processes in episodic retrieval: an fMRI study. Functional magnetic resonance imaging.

    PubMed

    Tsukiura, Takashi; Fujii, Toshikatsu; Takahashi, Toshimitsu; Xiao, Ruiting; Sugiura, Motoaki; Okuda, Jiro; Iijima, Toshio; Yamadori, Atsushi

    2002-12-01

    Previous studies have reported that the medial temporal lobe (MTL) structures contribute to the processing of relations among multiple stimuli in episodic encoding. There have been few studies, however, on the episodic retrieval requiring processing of relations among multiple components that was involved in our events. We used functional magnetic resonance imaging (fMRI) to investigate neural activities during the retrieval of relations within an organized episode and the recognition of an episodic component. Healthy, normal participants memorized 50 four-scene comic strips before fMRI scanning. In the retrieval phase with fMRI scanning, participants were engaged in three tasks: a visual identification (VI) task, a story recall (SR) task, and a picture recognition (PRe) task. In the VI task, participants were asked to judge whether they could identify at least one female character in the two scenes presented vertically. In the SR task, participants were shown the first and last scenes from strips memorized previously and asked to judge whether or not the two scenes were from the same strip. In the PRe task, participants were shown two scenes and asked to judge whether they both belonged to the memorized scenes. The two contrasts of SR with VI and PRe with VI demonstrated some commonly activated areas, such as the bilateral middle frontal gyrus and cerebellum. More importantly, the SR task differentially activated the bilateral parahippocampal gyrus, whereas the PRe task differentially activated right prefrontal areas, including the inferior frontal and precentral gyri. The results suggest that the activity of the MTL structures may be strongly associated with episodic memory retrieval requiring context-dependent relational processing. PMID:12395388

  20. Appl. Magn. Reson. 28, 1XXX (2005) Magnetic Resonance

    E-print Network

    Baker, Chris I.

    Appl. Magn. Reson. 28, 1XXX (2005) Applied Magnetic Resonance © Springer-Verlag 2005 Printed-based functional magnetic resonance imaging (fMRI) techniques have proven to be extremely robust and sensitive firing spatially and temporally integrates on the spatial scale of an MRI voxel to produce a magnetic

  1. Mapping the central effects of chronic ketamine administration in an adolescent primate model by functional magnetic resonance imaging (fMRI).

    PubMed

    Yu, Hongluan; Li, Qi; Wang, Defeng; Shi, Lin; Lu, Gang; Sun, Lin; Wang, Li; Zhu, Wei; Mak, Ying T; Wong, Naikei; Wang, Yixiang; Pan, Fang; Yew, David T

    2012-01-01

    Ketamine, a noncompetitive N-methyl-D-aspartic acid (NMDA) receptor antagonist, is capable of triggering excessive glutamate release and subsequent cortical excitation which may induce psychosis-like behavior and cognitive anomalies. Growing evidence suggests that acute ketamine administration can provoke dose-dependent positive and negative schizophrenia-like symptoms. While the acute effects of ketamine are primarily linked to aberrant activation of the prefrontal cortex and limbic structures with elevated glutamate and dopamine levels, the long-term effects of ketamine on brain functions and neurochemical homeostasis remain incompletely understood. In recent years, reports of ketamine abuse, especially among young individuals, have surged rapidly, with profound socioeconomic and health impacts. We herein investigated the chronic effects of ketamine on brain function integrity in an animal model of adolescent cynomolgus monkeys (Macaca fascicularis) by functional magnetic resonance imaging (fMRI). Immunohistochemical study was also conducted to examine neurochemical changes in the dopaminergic and cholinergic systems in the prefrontal cortex following chronic ketamine administration. Our results suggest that repeated exposure to ketamine markedly reduced neural activities in the ventral tegmental area, substantia nigra in midbrain, posterior cingulate cortex, and visual cortex in ketamine-challenged monkeys. In contrast, hyperfunction was observed in the striatum and entorhinal cortex. In terms of neurochemical and locomotive changes, chronically ketamine-challenged animals were found to have reduced tyrosine hydroxylase (TH) but not choline acetyltransferase (ChAT) levels in the prefrontal cortex, which was accompanied by diminished total movement compared with the controls. Importantly, the mesolimbic, mesocortical and entorhinal-striatal systems were found to be functionally vulnerable to ketamine's chronic effects. Dysfunctions of these neural circuits have been implicated in several neuropsychiatric disorders including depression, schizophrenia and attention deficit disorder (ADD). Collectively, our results support the proposition that repeated ketamine exposure can be exploited as a pharmacological paradigm for studying the central effects of ketamine relevant to neuropsychiatric disorders. PMID:22178134

  2. Magnetic Resonance

    Cancer.gov

    Focus Group on Magnetic Resonance Spectroscopy (MRS) in Clinical Oncology(April 1999) To explore the technical requirements for MRS and the application of hydrogen and multinuclear spectroscopy for tumor response to therapy.

  3. 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).

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

    ERIC Educational Resources Information Center

    Richards, Todd L.

    2001-01-01

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

  5. A Bayesian TimeCourse Model for Functional Magnetic Resonance Imaging Data

    E-print Network

    Genovese, Christopher

    A Bayesian Time­Course Model for Functional Magnetic Resonance Imaging Data Christopher R. Genovese Functional Magnetic Resonance Imaging (fMRI) is a new technique for studying the workings of the active human brain. During an fMRI ex­ periment, a sequence of Magnetic Resonance images is acquired while a subject

  6. Principles of functional Magnetic Resonance Martin A. Lindquist

    E-print Network

    1 Principles of functional Magnetic Resonance Imaging Martin A. Lindquist Department of Magnetic Resonance Signal Generation ............. 6 1.2.1.1 The MRI Scanner ...................................................... 40 1.1 Introduction Functional Magnetic Resonance Imaging (fMRI) is a non-invasive technique

  7. Exploring brain function with magnetic resonance imaging

    Microsoft Academic Search

    F. Di Salle; E. Formisano; D. E. J. Linden; R. Goebel; S. Bonavita; A. Pepino; F. Smaltino; G. Tedeschi

    1999-01-01

    Since its invention in the early 1990s, functional magnetic resonance imaging (fMRI) has rapidly assumed a leading role among the techniques used to localize brain activity. The spatial and temporal resolution provided by state-of-the-art MR technology and its non-invasive character, which allows multiple studies of the same subject, are some of the main advantages of fMRI over the other functional

  8. A Penalized Likelihood Approach to Magnetic Resonance Image Reconstruction

    E-print Network

    Magnetic Resonance Imaging (fMRI) technology are reconstructed using the discrete inverse Fourier transform is that the images obtained from MRI technology can be very noisy due to various factors, such as motionMRI), which is used to study the activation patterns of the brain. In fMRI, a series of MR images of the brain

  9. Magnetic resonance angiography

    MedlinePLUS

    MRA; Angiography - magnetic resonance ... Kwong RY. Cardiovascular Magnetic Resonance Imaging. In: Bonow RO, Mann DL, Zipes DP, Libby P, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine . ...

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

    PubMed Central

    Rogers, Gary L

    2003-01-01

    PURPOSE: To evaluate the effects of a single dose of levodopa on visual cortex, based on functional MRI (fMRI), and on visual function, based on psychophysical tests, in amblyopic and normal subjects. METHOD: A prospective, randomized trial of a single dose of levodopa (2 mg/kg body weight) was undertaken in an institutional setting in nine normal and six amblyopic subjects, who were assessed at baseline and 90 minutes after levodopa ingestion. fMRI of occipital visual cortex was undertaken with a 1.5T GE MRI scanner utilizing the BOLD contrast technique. fMRI stimuli were two gratings (0.5, 2.0 cycles/degree of visual angle) that counterphased at 4 Hz. fMRI parameters for analysis included AREA and LEVEL of activation and a SUMMED score (AREA x LEVEL). Psychophysical tests included visual acuity, contrast sensitivity, stereoacuity, and binocular fusion. RESULTS: At baseline, AREA of activation (P = .05) and SUMMED score (P = .05) were significantly less in the amblyopic compared to the dominant eyes. Psychophysically, visual acuity and contrast sensitivity were significantly worse in the amblyopic eye. Following levodopa ingestion, there was significant decrease in LEVEL of activation in the amblyopic eye, even though visual acuity showed significant improvement (P = .03). Also, amblyopes showed a significant increase and normals showed some decrease in interocular difference in LEVEL of activation (P = .04). CONCLUSION: Unique information was obtained when fMRI was utilized to assess visual cortical function. While levodopa improved visual acuity in the amblyopic eye, it decreased the LEVEL of activation based on fMRI, a counterintuitive finding. The results highlight the value of utilizing fMRI to assess amblyopia and provide new directions for research. PMID:14971587

  11. Overview of Functional Magnetic Resonance Imaging

    PubMed Central

    Glover, Gary H.

    2010-01-01

    Synopsis Blood Oxygen Level Dependent (BOLD) functional magnetic resonance imaging (fMRI) depicts changes in deoxyhemoglobin concentration consequent to task-induced or spontaneous modulation of neural metabolism. Since its inception in 1990, this method has been widely employed in thousands of studies of cognition for clinical applications such as surgical planning, for monitoring treatment outcomes, and as a biomarker in pharmacologic and training programs. Technical developments have solved most of the challenges of applying fMRI in practice. These challenges include low contrast to noise ratio of BOLD signals, image distortion, and signal dropout. More recently, attention is turning to the use of pattern classification and other statistical methods to draw increasingly complex inferences about cognitive brain states from fMRI data. This paper reviews the methods, some of the challenges and the future of fMRI. PMID:21435566

  12. Parietal and cingulate processes in central pain. A combined positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) study of an unusual case

    Microsoft Academic Search

    R. Peyron; L. Garc??a-Larrea; M. C. Grégoire; P. Convers; A. Richard; F. Lavenne; F. G. Barral; F. Mauguière; D. Michel; B. Laurent

    2000-01-01

    Parietal, insular and anterior cingulate cortices are involved in the processing of noxious inputs and genesis of pain sensation. Parietal lesions may generate central pain by mechanisms generally assumed to involve the ‘medial’ pain system (i.e. medial thalamic nuclei and anterior cingulate cortex (ACC)). We report here PET and fMRI data in a patient who developed central pain and allodynia

  13. Training fMRI Classifiers to Detect Cognitive States across Multiple Human Subjects

    E-print Network

    Training fMRI Classifiers to Detect Cognitive States across Multiple Human Subjects Xuerui Wang observed via functional Magnetic Resonance Imaging (fMRI). This problem is important because different fMRI data sets. 1 Introduction The advent of functional Magnetic Resonance Imaging (fMRI) has made

  14. Subspaces of Spatially Varying Independent Components in fMRI

    E-print Network

    Ylipaavalniemi, Jarkko

    Subspaces of Spatially Varying Independent Components in fMRI Jarkko Ylipaavalniemi1,2 and Ricardo) is commonly used in functional magnetic resonance imaging (fMRI) studies to identify, in a blind man- ner that maximally correlate with the stimuli. 1 Introduction Functional magnetic resonance imaging (fMRI) is one

  15. MRI (Magnetic Resonance Imaging)

    MedlinePLUS

    ... Radiation-Emitting Products and Procedures Medical Imaging MRI (Magnetic Resonance Imaging) Description Uses Risks/Benefits Information for ... Regulations & Performance Standards Industry Guidance Other Resources Description Magnetic resonance imaging (MRI) is a medical imaging procedure ...

  16. Optically Enhanced Magnetic Resonance

    E-print Network

    Suter, Dieter

    Optically Enhanced Magnetic Resonance Dieter Suter Universit¨at Dortmund, Germany 1 Introduction 1.1 Motivation The physical mechanism of nuclear magnetic resonance spectroscopy, the excitation of transitions. In most magnetic resonance experiments, these couplings are used to monitor the environment of the nuclei

  17. Magnetic Resonance Spectroscopy (MRS)

    E-print Network

    Mandal, Pravat K.

    Magnetic Resonance Spectroscopy (MRS) and Its Application in Alzheimer's Disease PRAVAT K. MANDAL1, Pennsylvania ABSTRACT: Magnetic resonance spectroscopy (MRS) is a noninvasive tool to measure the chemical; PRESS; STEAM; 2D MRS; Alzheimer's disease I. INTRODUCTION Magnetic resonance spectroscopy (MRS) is a rap

  18. 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.

  19. [Magnetic resonance spectroscopy].

    PubMed

    Tsa?, I V; Kulikov, S A; Kozinets, G I

    2001-06-01

    Life-time diagnosis of the initial pathological shifts in the organism remains an and still unsolved important problem of modern medicine. Magnetic resonance spectroscopy based on the nuclear magnetic resonance phenomenon is one of the methods which can help to solve this problem. Modern reports about the use of magnetic resonance spectroscopy in the diagnosis of various diseases are reviewed. PMID:11521591

  20. Functional magnetic resonance imaging in schizophrenia

    PubMed Central

    Gur, Raquel E.; Gur, Ruben C.

    2010-01-01

    The integration of functional magnetic resonance imaging (fMRI) with cognitive and affective neuroscience paradigms enables examination of the brain systems underlying the behavioral deficits manifested in schizophrenia; there have been a remarkable increase in the number of studies that apply fMRI in neurobiological studies of this disease. This article summarizes features of fMRI methodology and highlights its application in neurobehavioral studies in schizophrenia. Such work has helped elucidate potential neural substrates of deficits in cognition and affect by providing measures of activation to neurobehavioral probes and connectivity among brain regions. Studies have demonstrated abnormalities at early stages of sensory processing that may influence downstream abnormalities in more complex evaluative processing. The methodology can help bridge integration with neuropharmacologic and genomic investigations. PMID:20954429

  1. Impact of fMRI Environment on Cognitive Function 

    E-print Network

    Sim, Tony

    2011-01-01

    Functional magnetic resonance imaging (fMRI) is an increasingly important tool in psychological research, but its reliability is somewhat undermined by concerns about the fMRI environment’s impact on cognition. The unusual scanner environment...

  2. 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 ...

  3. Sensors for Applications in Magnetic Resonance Environments

    Microsoft Academic Search

    Roger Gassert; Dominique Chapuis; Hannes Bleuler; Etienne Burdet

    2008-01-01

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

  4. Functional magnetic resonance imaging using RASER

    PubMed Central

    Goerke, Ute; Garwood, Michael; Ugurbil, Kamil

    2010-01-01

    Although functional imaging of neuronal activity by magnetic resonance imaging (fMRI) has become the primary methodology employed in studying the brain, significant portions of the brain are inaccessible by this methodology due to its sensitivity to macroscopic magnetic field inhomogeneities induced near air filled cavities in the head. In this paper, we demonstrate that this sensitivity is eliminated by a novel pulse sequence, RASER (rapid acquisition by sequential excitation and refocusing) (Chamberlain et al., 2007), that can generate functional maps. This is accomplished because RASER acquired signals are purely and perfectly T2 weighted, without any T2*-effects that are inherent in the other image acquisition schemes employed to date. T2-weighted fMRI sequences are also more specific to the site of neuronal activity at ultrahigh magnetic fields than T2*-variations since they are dominated by signal components originating from the tissue in the capillary bed. The RASER based fMRI response is quantified; it is shown to have inherently less noisy time series and to provide fMRI in brain regions, such as the orbitofrontal cortex, which are challenging to image with conventional techniques. PMID:20699123

  5. 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...

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

    Microsoft Academic Search

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

    2004-01-01

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

  7. Linear Systems Analysis of Functional Magnetic Resonance Imaging in Human V1

    Microsoft Academic Search

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

    1996-01-01

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

  8. 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.

  9. Nuclear magnetic resonance gyroscope

    Microsoft Academic Search

    F. A. Karwacki; J. Griffin

    1985-01-01

    A nuclear magnetic resonance gyroscope which derives angular rotation from the phases of precessing nuclear moments utilizes a single-resonance cel 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 readout beam and associated electronics for signal processing

  10. A STATISTICAL FMRI MODEL FOR DIFFERENTIAL T2* CONTRAST INCORPORATING T1 AND T2* OF

    E-print Network

    Rowe, Daniel B.

    A STATISTICAL FMRI MODEL FOR DIFFERENTIAL T2* CONTRAST INCORPORATING T1 AND T2* OF GRAY MATTER By M;ABSTRACT A STATISTICAL FMRI MODEL FOR DIFFERENTIAL T2* CONTRAST INCORPORATING T1 AND T2* OF GRAY MATTER M are two main study areas in magnetic resonance imaging (MRI) and functional magnetic resonance imaging (fMRI

  11. BLIND SOURCE SEPARATION APPROACHES TO REMOVE IMAGING ARTEFACTS IN EEG SIGNALS RECORDED SIMULTANEOUSLY WITH FMRI

    E-print Network

    Paris-Sud XI, Université de

    SIMULTANEOUSLY WITH FMRI Bertrand Rivet1,2 , Guillaume Flandin3 , Antoine Souloumiac2 , Jean-Baptiste Poline3 1 functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) is a growing field in hu- man. INTRODUCTION The combination of electroencephalography (EEG) and functional magnetic resonance imaging (fMRI

  12. COMPLEXICA FOR FMRI ANALYSIS: PERFORMANCEOF SEVERALAPPROACHES V. Calhoun'."nd T. Adali3

    E-print Network

    Adali, Tulay

    COMPLEXICA FOR FMRI ANALYSIS: PERFORMANCEOF SEVERALAPPROACHES V. Calhoun'."nd T. Adali3 `Neuro, such as functional magnetic resonance imaging data. Functional magnetic resonance imaging (fMRI) is a technique that produces complex-valued data; however the vast majority of fMRI analyses utilize only magnitude images. We

  13. fMRI Measurements of Human Visual Cortex Nature, June 16. v. 369, p. 525.

    E-print Network

    Rotstein, Horacio G.

    1 fMRI Measurements of Human Visual Cortex Nature, June 16. v. 369, p. 525. Sir | The primate is typically 7 to 10 mm. Using functional magnetic resonance imaging fMRI, we made detailed measurements of this stimulus while fMRI measurements of neural activation were continuously acquired. The fMRI signal that we

  14. Short Communication fMRI of Deep Brain Stimulation at the Rat Ventral Posteromedial Thalamus

    E-print Network

    Duong, Timothy Q.

    Short Communication fMRI of Deep Brain Stimulation at the Rat Ventral Posteromedial Thalamus Q3 Yen stimulation fMRI Thalamus Rat Isoflurane a b s t r a c t Background: Functional magnetic resonance imaging (fMRI of the thalamocortical tract using DBS fMRI at the rat ventral posteromedial thalamus. Methods: Blood oxygenation level

  15. fMRI, the Star/Plus experiment and our toolbox Francisco Pereira

    E-print Network

    Mitchell, Tom

    fMRI, the Star/Plus experiment and our toolbox Francisco Pereira February 13, 2002 1 fMRI 1.1 Overview Functional Magnetic Resonance Imaging (fMRI) is a technique for obtaining three-dimensional images increase in the ratio of oxygenated to deoxygenated haemoglobin, which a#11;ects the fMRI signal [see mini

  16. Ultra high-resolution fMRI and electrophysiology of the rat primary somatosensory cortex

    E-print Network

    Duong, Timothy Q.

    Ultra high-resolution fMRI and electrophysiology of the rat primary somatosensory cortex Yen-Yu Ian: Accepted 28 January 2013 Available online 4 February 2013 Keywords: fMRI High-resolution Cerebral blood-magnetic-resonance-imaging (fMRI) has been used to study brain functions at in- creasingly finer scale, but whether fMRI can

  17. ORIGINAL ARTICLE Assessing a signal model and identifying brain activity from fMRI

    E-print Network

    Gao, Jianbo

    ORIGINAL ARTICLE Assessing a signal model and identifying brain activity from fMRI data-Verlag 2008 Abstract One of the major challenges of functional magnetic resonance imaging (fMRI) data analysis brain activity from fMRI data. We perform three tasks: (a) Estimating noise level from experimental fMRI

  18. Human Brain Language Areas Identified by Functional Magnetic Resonance Imaging

    Microsoft Academic Search

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

    1997-01-01

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

  19. Magnetic Resonance Imaging and Magnetic Resonance Spectroscopy in Dementias

    Microsoft Academic Search

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

    2001-01-01

    This article reviews recent studies of magnetic resonance imaging and magnetic resonance spectroscopy in demen tia, 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 spec troscopy can detect structural alteration and biochemical abnormalities in the brain of demented subjects and may help in the differential

  20. Magnetic Resonance Imaging Outcomes From a Comprehensive Magnetic Resonance Study of Children With Fetal Alcohol Spectrum Disorders

    Microsoft Academic Search

    Susan J. Astley; Elizabeth H. Aylward; Heather Carmichael Olson; Kimberly Kerns; Allison Brooks; Truman E. Coggins; Julian Davies; Susan Dorn; Beth Gendler; Tracy Jirikowic; Paul Kraegel; Kenneth Maravilla; Todd Richards

    2009-01-01

    Background: Magnetic resonance (MR) technology offers noninvasive methods for in vivo assessment of neuroabnormalities. Methods: A comprehensive neuropsychological ? psychiatric battery, coupled with MR imaging, (MRI), MR spectroscopy (MRS), and functional MRI (fMRI) assessments, were administered to children with fetal alcohol spectrum disorders (FASD) to determine if global and ? or focal abnor- malities could be identified, and distinguish diagnostic

  1. 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.

  2. Special considerations/technical limitations of blood-oxygen-level-dependent functional magnetic resonance imaging.

    PubMed

    Zacà, Domenico; Agarwal, Shruti; Gujar, Sachin K; Sair, Haris I; Pillai, Jay J

    2014-11-01

    In this review, limitations affecting the results of presurgical mapping with blood-oxygen-level-dependent (BOLD) functional magnetic resonance imaging (fMRI) are discussed. There is a great need to standardize fMRI acquisition and analysis methods and establish guidelines to address quality control issues. Several national and international organizations are formulating guidelines and standards for both clinical and research applications of BOLD fMRI. Consensus regarding management of these issues will likely both improve the clinical standard of care and enhance future research applications of fMRI. PMID:25441509

  3. Analyzing fMRI experiments with structural adaptive smoothing procedures

    E-print Network

    Spokoiny, Vladimir

    Author's personal copy Analyzing fMRI experiments with structural adaptive smoothing procedures Available online 4 August 2006 Data from functional magnetic resonance imaging (fMRI) consist of time series and to improve signal detection, the fMRI data are spatially smoothed. However, the common application

  4. Object Recognition Insights From Advances in fMRI Methods

    E-print Network

    Grill-Spector, Kalanit

    Object Recognition Insights From Advances in fMRI Methods Kalanit Grill-Spector and Rory Sayres of standard functional magnetic resonance imaging (fMRI) and discuss methodological advancements, including fMRI-adaptation, pattern ana- lyses, and high-resolution fMRI, that may be more appro- priate for studying object and face

  5. A Multivariate Approach to Estimate Complexity of FMRI Time Series

    E-print Network

    A Multivariate Approach to Estimate Complexity of FMRI Time Series Henry Sch¨utze1,2 , Thomas magnetic resonance imaging, fMRI) produce large amounts of data. To adequately describe the underlying (MPSE), a multivariate entropy ap- proach that estimates spatio-temporal complexity of fMRI time series

  6. Magnetic Resonance Imaging

    NSDL National Science Digital Library

    2014-09-18

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

  7. Naive random subspace ensemble with linear classifiers for real-time classification of fMRI data

    E-print Network

    Kuncheva, Ludmila I.

    Naive random subspace ensemble with linear classifiers for real-time classification of fMRI data: Functional magnetic resonance imaging (fMRI) Online classification Naive labelling Classifier ensembles a b s t r a c t Functional magnetic resonance imaging (fMRI) provides a spatially accurate measure of brain

  8. Brain Activation in Parkinson's Disease during a Functional Magnetic Resonance Imaging Set Shifting Task: Preliminary Findings

    E-print Network

    Lichtarge, Olivier

    Brain Activation in Parkinson's Disease during a Functional Magnetic Resonance Imaging Set Shifting with Parkinson's disease (PD) and age-matched controls using event-related functional magnetic resonance imaging (fMRI). Cognitive impairment is a common non-motor manifestation of Parkinson's disease (PD

  9. 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.

  10. Resonant and non-resonant magnetic scattering

    SciTech Connect

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

    1991-01-01

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

  11. Resonant and non-resonant magnetic scattering

    SciTech Connect

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

    1991-12-31

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

  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. 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.

  14. Clinical magnetic resonance imaging

    SciTech Connect

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

    1988-01-01

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

  15. Nuclear magnetic resonance imaging

    SciTech Connect

    Young, I.R.

    1984-07-03

    A method of imaging a body by nuclear magnetic resonance wherein volume scanning of a region of the body is achieved by scanning a first planar slice of the region and at least one further slice of the region in the relaxation time for the scan of the first slice.

  16. 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 ...

  17. Resonant Magnetic Vortices

    E-print Network

    Yves Décanini; Antoine Folacci

    2002-12-23

    By using the complex angular momentum method, we provide a semiclassical analysis of electron scattering by a magnetic vortex of Aharonov-Bohm-type. Regge poles of the $S$-matrix are associated with surface waves orbiting around the vortex and supported by a magnetic field discontinuity. Rapid variations of sharp characteristic shapes can be observed on scattering cross sections. They correspond to quasibound states which are Breit-Wigner-type resonances associated with surface waves and which can be considered as quantum analogues of acoustic whispering-gallery modes. Such a resonant magnetic vortex could provide a new kind of artificial atom while the semiclassical approach developed here could be profitably extended in various areas of the physics of vortices.

  18. Introduction Magnetic Resonance Imaging (MRI)

    E-print Network

    Wirosoetisno, Djoko

    Introduction Statistics Magnetic Resonance Imaging (MRI) Statistics in the UK Statistics at UCL and Beyond #12;Introduction Statistics Magnetic Resonance Imaging (MRI) Statistics in the UK Statistics Magnetic Resonance Imaging (MRI) Statistics in the UK Statistics at UCL Outline Why do Statistics? Some

  19. Parallel Magnetic Resonance Imaging

    E-print Network

    Uecker, Martin

    2015-01-01

    The main disadvantage of Magnetic Resonance Imaging (MRI) are its long scan times and, in consequence, its sensitivity to motion. Exploiting the complementary information from multiple receive coils, parallel imaging is able to recover images from under-sampled k-space data and to accelerate the measurement. Because parallel magnetic resonance imaging can be used to accelerate basically any imaging sequence it has many important applications. Parallel imaging brought a fundamental shift in image reconstruction: Image reconstruction changed from a simple direct Fourier transform to the solution of an ill-conditioned inverse problem. This work gives an overview of image reconstruction from the perspective of inverse problems. After introducing basic concepts such as regularization, discretization, and iterative reconstruction, advanced topics are discussed including algorithms for auto-calibration, the connection to approximation theory, and the combination with compressed sensing.

  20. Cardiac Magnetic Resonance Imaging

    Microsoft Academic Search

    Michael Jerosch-Herold; Ravi Teja Seethamraju; Carsten Rickers

    Magnetic resonance imaging (MRI) has proven to be extremely versatile and useful for studying cardiac anatomy and function,\\u000a both for providing a deeper understanding of cardiac physiology and as a means to diagnose cardiac diseases. The capabilities\\u000a of MRI as a tomographic imaging modality to capture, with high spatial resolution, the anatomy of 3D structures was already\\u000a well appreciated before

  1. IEEE TRANSACTIONS ON NEURAL SYSTEMS AND REHABILITATION ENGINEERING, VOL. 16, NO. 6, DECEMBER 2008 539 Interpretable Classifiers for fMRI Improve

    E-print Network

    Knutson, Brian

    539 Interpretable Classifiers for fMRI Improve Prediction of Purchases Logan Grosenick, Stephanie magnetic resonance imaging (fMRI) is a promising technology for such applications. However, fMRI data's low to examine the ability of fMRI activation in three regions--the nucleus accum- bens (NAcc), medial prefrontal

  2. Magnetic Resonance Facility (Fact Sheet)

    SciTech Connect

    Not Available

    2012-03-01

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

  3. fMRI Supports the Sensorimotor Theory of Motor Resonance

    Microsoft Academic Search

    Claire Landmann; Sofia M. Landi; Scott T. Grafton; Valeria Della-Maggiore

    2011-01-01

    The neural mechanisms mediating the activation of the motor system during action observation, also known as motor resonance, are of major interest to the field of motor control. It has been proposed that motor resonance develops in infants through Hebbian plasticity of pathways connecting sensory and motor regions that fire simultaneously during imitation or self movement observation. A fundamental problem

  4. Nuclear Magnetic Resonance Gyroscope

    NASA Astrophysics Data System (ADS)

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

    2012-06-01

    The navigation grade micro Nuclear Magnetic Resonance Gyroscope (micro-NMRG) being developed by the Northrop Grumman Corporation is concluding 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 poster will describe the history, operational principles, and design basics of the NMRG including an overview of the NSD designs developed and demonstrated in the DARPA gyro development program. General performance results from phases 3 and 4 will also be presented.

  5. Selective Averaging of Rapidly Presented Individual Trials Using fMRI

    E-print Network

    Rotstein, Horacio G.

    Selective Averaging of Rapidly Presented Individual Trials Using fMRI Anders M. Dale* and Randy L-related potential (ERP) experiments could be used to demonstrate functional magnetic resonance imaging (fMRI of full-field visual checkerboard stimulation, the fMRI blood oxygenation level-dependent (BOLD) signal

  6. Tools of the Trade Studying mind and brain with fMRI

    E-print Network

    Jonides, John

    Tools of the Trade Studying mind and brain with fMRI Marc G. Berman, John Jonides, and Derek Evan using functional magnetic resonance imaging (fMRI) warrants an examination of how the technique is being used to study processes of mind and brain. Here, we propose a classification of fMRI studies

  7. fMRI Compatible Haptic Interface Actuated with Traveling Wave Ultrasonic Motor

    E-print Network

    Psaltis, Demetri

    fMRI Compatible Haptic Interface Actuated with Traveling Wave Ultrasonic Motor Markus Flueckiger are developing haptic interfaces compatible with functional Magnetic Resonance Imaging (fMRI) for neuroscience electronic components outside the shielded MR room. Hence, the device can be used in conjunction with fMRI

  8. Novemeber 22, 1999 The Role of Context in Visual Perception: An fMRI Study

    E-print Network

    Novemeber 22, 1999 The Role of Context in Visual Perception: An fMRI Study Thomas E. Nichols, William F. Eddy, and James L. McClelland We use Functional Magnetic Resonance Imaging (fmri) to test two. The central goal of this work is to use fmri to look for evidence for ``top down'' effects in visual

  9. VARIATIONAL VARIABLE SELECTION TO ASSESS EXPERIMENTAL CONDITION RELEVANCE IN EVENT-RELATED FMRI

    E-print Network

    Paris-Sud XI, Université de

    VARIATIONAL VARIABLE SELECTION TO ASSESS EXPERIMENTAL CONDITION RELEVANCE IN EVENT-RELATED FMRI accounted for in most functional Magnetic Resonance Imaging (fMRI) analysis which usually assumes that all and real fMRI data. Index Terms-- Irrelevance detection, Stimulus type se- lection, Joint detection

  10. Data-driven fMRI data analysis based on parcellation.

    E-print Network

    Aickelin, Uwe

    Data-driven fMRI data analysis based on parcellation. Yongnan Ji Thesis submitted to The University 2010 #12;ii #12;Abstract Functional Magnetic Resonance Imaging (fMRI) is one of the most popular neu other neuroimaging tools, the group analysis of fMRI data often requires a transformation

  11. Joint maximum likelihood estimation of activation and Hemodynamic Response Function for fMRI q

    E-print Network

    Nosratinia, Aria

    Joint maximum likelihood estimation of activation and Hemodynamic Response Function for fMRI q form 28 January 2014 Accepted 29 March 2014 Available online 24 April 2014 Keywords: fMRI Hemodynamic s t r a c t Blood Oxygen Level Dependent (BOLD) functional magnetic resonance imaging (fMRI) maps

  12. Bayesian Analysis of fMRI data with Spatial Priors Will Penny and Guillaume Flandin

    E-print Network

    Penny, Will

    Bayesian Analysis of fMRI data with Spatial Priors Will Penny and Guillaume Flandin Wellcome Department of Imaging Neuroscience, University College, London WC1N 3BG. KEY WORDS: Bayesian, fMRI, spatial prior, GLM, variational 1. Introduction Functional Magnetic Resonance Imaging (fMRI) us- ing Blood

  13. Optimizing Design Efficiency of Free Recall Events for fMRI

    E-print Network

    Badre, David

    U ncorrected Proof Optimizing Design Efficiency of Free Recall Events for fMRI Ilke Ã?ztekin, Nicole with func- tional magnetic resonance imaging (fMRI). We used both theo- retically and empirically derived free recall latency distributions to generate simulated fMRI datasets and assessed design effi- ciency

  14. Antje Petzold An fMRI Study on Context-Dependent Processing of

    E-print Network

    Kallenrode, May-Britt

    Antje Petzold An fMRI Study on Context-Dependent Processing of Natural Visual Scenes PICS © Institute of Cognitive Science #12; Master's Thesis An fMRI Study on Context by salient features in a visual scene. Studies using functional Magnetic Resonance Imaging (fMRI) suggest

  15. Statistics and Its Interface Volume 3 (2010) 3343 Adaptive statistical parametric mapping for fMRI

    E-print Network

    Shen, Haipeng

    Statistics and Its Interface Volume 3 (2010) 33­43 Adaptive statistical parametric mapping for fMRI functional magnetic resonance imaging (fMRI). The process of identifying brain activation regions can the application of a penalized smoothing technique. Using a computer experiment and a real fMRI data set

  16. A MULTIVARIATE MODEL FOR COMPARISON OF TWO DATASETS AND ITS APPLICATION TO FMRI ANALYSIS

    E-print Network

    Adali, Tulay

    A MULTIVARIATE MODEL FOR COMPARISON OF TWO DATASETS AND ITS APPLICATION TO FMRI ANALYSIS Yi-Ou Li brain activation in functional magnetic resonance imaging (fMRI) data acquired during a simulated.g., fMRI data acquired for two different tasks, or, data col- lected from control and diseased groups

  17. IMPROVING FMRI ANALYSIS AND MR RECONSTRUCTION WITH THE INCORPORATION OF MR RELAXIVITIES AND

    E-print Network

    Rowe, Daniel B.

    IMPROVING FMRI ANALYSIS AND MR RECONSTRUCTION WITH THE INCORPORATION OF MR RELAXIVITIES of Philosophy Milwaukee, Wisconsin August 2014 #12;i ABSTRACT IMPROVING FMRI ANALYSIS AND MR RECONSTRUCTION Functional magnetic resonance imaging (fMRI) and functional connectivity MRI (fcMRI) use the physical

  18. Cardiovascular Magnetic Resonance Imaging

    NASA Astrophysics Data System (ADS)

    Pelc, Norbert

    2000-03-01

    Cardiovascular diseases are a major source of morbidity and mortality in the United States. Early detection of disease can often be used to improved outcomes, either through direct interventions (e.g. surgical corrections) or by causing the patient to modify his or her behavior (e.g. smoking cessation or dietary changes). Ideally, the detection process should be noninvasive (i.e. it should not be associated with significant risk). Magnetic Resonance Imaging (MRI) refers to the formation of images by localizing NMR signals, typically from protons in the body. As in other applications of NMR, a homogeneous static magnetic field ( ~0.5 to 4 T) is used to create ``longitudinal" magnetization. A magnetic field rotating at the Larmor frequency (proportional to the static field) excites spins, converting longitudinal magnetization to ``transverse" magnetization and generating a signal. Localization is performed using pulsed gradients in the static field. MRI can produce images of 2-D slices, 3-D volumes, time-resolved images of pseudo-periodic phenomena such as heart function, and even real-time imaging. It is also possible to acquire spatially localized NMR spectra. MRI has a number of advantages, but perhaps the most fundamental is the richness of the contrast mechanisms. Tissues can be differentiated by differences in proton density, NMR properties, and even flow or motion. We also have the ability to introduce substances that alter NMR signals. These contrast agents can be used to enhance vascular structures and measure perfusion. Cardiovascular MRI allows the reliable diagnosis of important conditions. It is possible to image the blood vessel tree, quantitate flow and perfusion, and image cardiac contraction. Fundamentally, the power of MRI as a diagnostic tool stems from the richness of the contrast mechanisms and the flexibility in control of imaging parameters.

  19. 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.

  20. Magnetic Resonance Imaging and Magnetic Resonance Angiography of Vertebrobasilar Dolichoectasia

    Microsoft Academic Search

    Franz T. Aichner; Stephan R. Felber; Günther G. Birbamer; Andrea Posch

    1993-01-01

    We performed magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) in 16 patients with vertebrobasilar dolichoectasia (VBD). Five patients had compressive cranial nerve deficits and 11 patients presented with transient or permanent ischemic deficits related to the vertebrobasilar system. VBD did not present with distinct clinical findings and no clear correlation between basilar artery ectasia and the presence of

  1. 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.

  2. NMR Nuclear Magnetic Resonance Nuclear magnetic resonance (NMR) is an effect whereby magnetic nuclei in

    E-print Network

    Cavanagh, John

    NMR Nuclear Magnetic Resonance Nuclear magnetic resonance (NMR) is an effect whereby magnetic resonance frequency which depends on the strength of the magnetic field and other factors. This allows nuclei in a magnetic field absorb and re-emit electromagnetic (EM) energy. This energy is at a specific

  3. A nuclear magnetic resonance gyroscope

    Microsoft Academic Search

    E. Kanegsberg

    1977-01-01

    A nuclear magnetic resonance (NMR) gyroscope is under development for use as a low cost angle sensor in strapdown inertial measurement systems. The gyro operates on the principle that the magnetic moments of certain atoms precess at a known frequency in a magnetic field and that changes in phase of this frequency can be sensed to determine the inertial angular

  4. 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.

  5. Spin-Echo fMRI in Humans Using High Spatial Resolutions and High Magnetic Fields

    E-print Network

    Duong, Timothy Q.

    cortex at 4 and 7 T. This study used high spatial resolution, afforded by the increased signal fields, such as 7 T, the contribution of large vessels to GRE BOLD decreases relative to the microvasSpin-Echo fMRI in Humans Using High Spatial Resolutions and High Magnetic Fields Essa Yacoub

  6. Functional magnetic resonance imaging: imaging techniques and contrast mechanisms.

    PubMed Central

    Howseman, A M; Bowtell, R W

    1999-01-01

    Functional magnetic resonance imaging (fMRI) is a widely used technique for generating images or maps of human brain activity. The applications of the technique are widespread in cognitive neuroscience and it is hoped they will eventually extend into clinical practice. The activation signal measured with fMRI is predicated on indirectly measuring changes in the concentration of deoxyhaemoglobin which arise from an increase in blood oxygenation in the vicinity of neuronal firing. The exact mechanisms of this blood oxygenation level dependent (BOLD) contrast are highly complex. The signal measured is dependent on both the underlying physiological events and the imaging physics. BOLD contrast, although sensitive, is not a quantifiable measure of neuronal activity. A number of different imaging techniques and parameters can be used for fMRI, the choice of which depends on the particular requirements of each functional imaging experiment. The high-speed MRI technique, echo-planar imaging provides the basis for most fMRI experiments. The problems inherent to this method and the ways in which these may be overcome are particularly important in the move towards performing functional studies on higher field MRI systems. Future developments in techniques and hardware are also likely to enhance the measurement of brain activity using MRI. PMID:10466145

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

    ERIC Educational Resources Information Center

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

    2000-01-01

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

  9. Application and validation of spatial mixture modelling for the joint detection-estimation of brain activity in fMRI

    E-print Network

    Paris-Sud XI, Université de

    activity in fMRI Thomas Vincent, Philippe Ciuciu and Jérôme Idier Abstract-- Within-subject analysis in event-related functional Magnetic Resonance Imaging (fMRI) first relies on (i) a detection step and the generative BOLD model and further extend comparison between SMM and IMM on real fMRI data, focusing

  10. Markov models for fMRI correlation structure: is brain functional connectivity small world, or decomposable into networks?

    E-print Network

    Paris-Sud XI, Université de

    Markov models for fMRI correlation structure: is brain functional connectivity small world-Sur-Yvette Abstract Correlations in the signal observed via functional Magnetic Resonance Imaging (fMRI), are expected of the fMRI signal, i.e. its Markov structure, to find realistic assumptions on the connectivity structure

  11. Neuroimaging of Love: fMRI Meta-Analysis Evidence toward New Perspectives in Sexual Medicinejsm_1999 1..12

    E-print Network

    Neuroimaging of Love: fMRI Meta-Analysis Evidence toward New Perspectives in Sexual Medicinejsm of functional magnetic resonance imaging (fMRI) studies to critically identify the cortical networks associated neuroimaging literature. Main Outcome Measures. Review of published literature on fMRI studies of love

  12. Fast joint detection-estimation of evoked brain activity in event-related fMRI using a

    E-print Network

    Paris-Sud XI, Université de

    1 Fast joint detection-estimation of evoked brain activity in event-related fMRI using-related fMRI data, two steps are usually performed separately: detection of brain activity and estimation;32(5):821-837" DOI : 10.1109/TMI.2012.2225636 #12;2 I. INTRODUCTION Functional Magnetic Resonance Imaging (fMRI

  13. Nuclear magnetic resonance contrast agents

    DOEpatents

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

    1997-01-01

    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.

  14. 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.

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

    PubMed Central

    Sharma, Rakesh; Sharma, Avdhesh

    2004-01-01

    Functional magnetic resonance imaging (fMRI) is recently developing as imaging modality used for mapping hemodynamics of neuronal and motor event related tissue blood oxygen level dependence (BOLD) in terms of brain activation. Image processing is performed by segmentation and registration methods. Segmentation algorithms provide brain surface-based analysis, automated anatomical labeling of cortical fields in magnetic resonance data sets based on oxygen metabolic state. Registration algorithms provide geometric features using two or more imaging modalities to assure clinically useful neuronal and motor information of brain activation. This review article summarizes the physiological basis of fMRI signal, its origin, contrast enhancement, physical factors, anatomical labeling by segmentation, registration approaches with examples of visual and motor activity in brain. Latest developments are reviewed for clinical applications of fMRI along with other different neurophysiological and imaging modalities. PMID:15125779

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

    Microsoft Academic Search

    Robert W. Cox

    1996-01-01

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

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

    Microsoft Academic Search

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

    1995-01-01

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

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

    Microsoft Academic Search

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

    1996-01-01

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

  19. 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…

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

    Microsoft Academic Search

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

    2010-01-01

    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

  1. 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,…

  2. 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,…

  3. 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

  4. FUSION OF CONCURRENT SINGLE TRIAL EEG DATA AND FMRI DATA USING MULTI-SET CANONICAL CORRELATION ANALYSIS

    E-print Network

    Adali, Tulay

    acquired functional magnetic resonance imaging (fMRI) and single trial electroencephalography (EEG) data, electroencephalography, multimodal analysis, multi-set canonical correlation analysis 1. INTRODUCTION Brain imaging techniques such as functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) provide com

  5. Nuclear magnetic resonance readable sensors

    E-print Network

    Ling, Yibo

    2010-01-01

    The monitoring of physiological biomarkers is fundamental to the diagnosis and treatment of disease. We describe here the development of molecular sensors which can be read by magnetic resonance (MR) relaxometry. MR is an ...

  6. Magnetic Resonance Imaging (MRI): Brain

    MedlinePLUS

    KidsHealth > Parents > Doctors & Hospitals > Medical Tests & Exams > Magnetic Resonance Imaging (MRI): Brain Print A A A Text Size What's in this article? What It Is Why It's Done Preparation Procedure What ...

  7. Bayesian Optimization of Magnetic Resonance Imaging Sequences

    E-print Network

    Seeger, Matthias

    Bayesian Optimization of Magnetic Resonance Imaging Sequences Matthias Seeger MMCI Cluster SAARLANDES Seeger (MMCI) Bayesian MRI Optimization 28 November 2008 1 / 19 #12;Outline 1 Magnetic Resonance) Bayesian MRI Optimization 28 November 2008 2 / 19 #12;Magnetic Resonance Imaging Magnetic Resonance Imaging

  8. 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

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

    Microsoft Academic Search

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

    1996-01-01

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

  10. A multivariate approach for processing magnetization effects in triggered event-related functional magnetic resonance imaging time series

    Microsoft Academic Search

    Fabrizio Esposito; Francesco Di Salle; Franciszek Hennel; Ornella Santopaolo; Marcus Herdener; Klaus Scheffler; Rainer Goebel; Erich Seifritz

    2006-01-01

    Triggered event-related functional magnetic resonance imaging requires sparse intervals of temporally resolved functional data acquisitions, whose initiation corresponds to the occurrence of an event, typically an epileptic spike in the electroencephalographic trace. However, conventional fMRI time series are greatly affected by non-steady-state magnetization effects, which obscure initial blood oxygen level-dependent (BOLD) signals. Here, conventional echo-planar imaging and a post-processing solution

  11. JAMA Patient Page: Magnetic Resonance Imaging

    MedlinePLUS

    ... of the American Medical Association JAMA PATIENT PAGE Magnetic Resonance Imaging M agnetic resonance imaging (MRI) uses magnetic fields ... of magnetic fields processed with highly sophisticated computers, MRI scans produce detailed and clear pictures of body parts. ...

  12. Magnetic Resonance Force Microscope Development

    SciTech Connect

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

    1999-06-03

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

  13. Optically Detected Magnetic Resonance Imaging

    E-print Network

    Blank, Aharon; Fischer, Ran; London, Paz; Gershoni, David

    2014-01-01

    Optically detected magnetic resonance (ODMR) provides ultrasensitive means to detect and image a small number of electron and nuclear spins, down to the single spin level with nanoscale resolution. Despite the significant recent progress in this field, it has never been combined with the power of pulsed magnetic resonance imaging (MRI) techniques. Here, we demonstrate for the first time how these two methodologies can be integrated using short pulsed magnetic field gradients to spatially-encode the sample. This results in what we denote as an "optically detected magnetic resonance imaging" (ODMRI) technique. It offers the advantage that the image is acquired in parallel from all parts of the sample, with well-defined three-dimensional point-spread function, and without any loss of spectroscopic information. In addition, this approach may be used in the future for parallel but yet spatially-selective efficient addressing and manipulation of the spins in the sample. Such capabilities are of fundamental importan...

  14. Optically detected magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Blank, Aharon; Shapiro, Guy; Fischer, Ran; London, Paz; Gershoni, David

    2015-01-01

    Optically detected magnetic resonance provides ultrasensitive means to detect and image a small number of electron and nuclear spins, down to the single spin level with nanoscale resolution. Despite the significant recent progress in this field, it has never been combined with the power of pulsed magnetic resonance imaging techniques. Here, we demonstrate how these two methodologies can be integrated using short pulsed magnetic field gradients to spatially encode the sample. This result in what we denote as an "optically detected magnetic resonance imaging" technique. It offers the advantage that the image is acquired in parallel from all parts of the sample, with well-defined three-dimensional point-spread function, and without any loss of spectroscopic information. In addition, this approach may be used in the future for parallel but yet spatially selective efficient addressing and manipulation of the spins in the sample. Such capabilities are of fundamental importance in the field of quantum spin-based devices and sensors.

  15. Magnetic Resonance Imaging (MRI)

    MedlinePLUS

    ... addition, any credit cards or anything else with magnetic coding that is near the magnet will be erased by most MRI systems. MRI works by contrasting the differences present in the area being scanned. Different ... ways to the magnetic field that is applied; it is these differences ...

  16. 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.

  17. 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.

  18. Applied Magnetic Resonance ISSN 0937-9347

    E-print Network

    1 23 Applied Magnetic Resonance ISSN 0937-9347 Volume 42 Number 3 Appl Magn Reson (2012) 42:353-361 DOI 10.1007/s00723-011-0298-1 Transverse Relaxation of Scalar Coupled Protons in Magnetic Resonance Relaxation of Scalar Coupled Protons in Magnetic Resonance of Non-Deuterated Proteins Takuya F. Segawa

  19. Magnetic Resonance Imaging (MRI)

    MedlinePLUS

    ... doctors use to see the body's organs and structures. MRI uses a magnetic field and radio waves to create detailed pictures of the body's insides. Unlike CAT scans or X-rays, MRI doesn't use radiation. An MRI scanner is a large doughnut-shaped magnet that often has a tunnel in the center. ...

  20. 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

  1. ON ICA OF COMPLEX-VALUED FMRI: ADVANTAGES AND ORDER SELECTION Wei Xiong, Yi-Ou Li, Hualiang Li, Tulay Adali

    E-print Network

    Adali, Tulay

    ON ICA OF COMPLEX-VALUED FMRI: ADVANTAGES AND ORDER SELECTION Wei Xiong, Yi-Ou Li, Hualiang Li, T ABSTRACT Functional magnetic resonance imaging (fMRI) data are originally acquired as complex-valued images, while virtu- ally all fMRI studies only use the magnitude of the data in the analysis. Since little

  2. ON ICA OF COMPLEX-VALUED FMRI: ADVANTAGES AND ORDER SELECTION Wei Xiong, Yi-Ou Li, Hualiang Li, Tulay Adal!

    E-print Network

    Adali, Tulay

    ON ICA OF COMPLEX-VALUED FMRI: ADVANTAGES AND ORDER SELECTION Wei Xiong, Yi-Ou Li, Hualiang Li, T ABSTRACT Functional magnetic resonance imaging (fMRI) data are originally acquired as complex-valued images, while virtu- ally all fMRI studies only use the magnitude of the data in the analysis. Since little

  3. Elimination of k-space spikes in fMRI data Xiaodong Zhang, Pierre-Francois Van De Moortele, Josef Pfeuffer, Xiaoping Hu*

    E-print Network

    Elimination of k-space spikes in fMRI data Xiaodong Zhang, Pierre-Francois Van De Moortele, Josef magnetic resonance imaging (fMRI) can be easily overwhelmed by noise of various origins. Spikes in the collected fMRI raw data often arise from high-duty usage of the scanner hardware and can introduce

  4. 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

  5. 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

  6. Visual mapping using blood oxygen level dependent functional magnetic resonance imaging.

    PubMed

    DeYoe, Edgar A; Raut, Ryan V

    2014-11-01

    Functional magnetic resonance imaging (fMRI) is used clinically to map the visual cortex before brain surgery or other invasive treatments to achieve an optimal balance between therapeutic effect and the avoidance of postoperative vision deficits. Clinically optimized stimuli, behavioral task, analysis, and displays permit identification of cortical subregions supporting high-acuity central vision that is critical for reading and other essential visual functions. Emerging techniques such as resting-state fMRI may facilitate the use of fMRI-based vision mapping in a broader range of patients. PMID:25441501

  7. Magnetic Resonance Cholangiopancreatography (MRCP)

    MedlinePLUS

    ... the magnet, radio waves redirect alignment of hydrogen atoms that naturally exist within the body without causing ... chemical changes in the tissues. As the hydrogen atoms return to their usual alignment, they emit energy ...

  8. Nuclear magnetic resonance scanners

    SciTech Connect

    Danby, G.T.; Hsieh, H.C.H.; Jackson, J.W.; Damadian, R.V.

    1988-08-23

    This patent describes a medical NMR scanner comprising a primary field magnet assembly including: (a) a ferromagnetic frame defining a patient-receiving space adapted to receive a human body, the frame having a pair of opposed polar regions aligned on a polar axis and disposed on opposite sides of the patient-receiving space, and the frame including a substantially continuous ferro-magnetic flux return path extending between the polar regions remote from the patient-receiving space; (b) flux-generating means including superconductive windings and cryostat means for maintaining the windings at superconducting temperatures; and (c) support means for maintaining the windings in proximity to the frame so that when a current passes through the windings magnetic flux emanating from the windings produces a magnetic field within the patient-receiving space and at least a portion of the flux passes into the patient-receiving space by way of the polar regions.

  9. 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

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

    PubMed

    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

  11. Magnetic Resonance Imaging of concrete

    E-print Network

    Burgoyne, Chris

    1 Magnetic Resonance Imaging of concrete Dr Chris Burgoyne Department of Engineering University of Cambridge Assessment of Concrete Structures · How can we tell what is going on inside concrete? · We would like to know:- · Has the concrete hardened? · Is there corrosion? · Is there cracking? · Where

  12. International Society for Magnetic Resonance in Medicine

    MedlinePLUS

    ... full list. Of Special Note ISMRM Online Education Magnetic Resonance in Medicine 30th Anniversary (Password required) In ... archive Who We Are The International Society for Magnetic Resonance in Medicine is a nonprofit professional association ...

  13. Magnetic Resonance Imaging (MRI) during Pregnancy

    MedlinePLUS

    Magnetic Resonance Imaging (MRI) During Pregnancy Play Video Clip (00:02:58) Your Radiologist Explains MRI During ... during the exam? Contrast material MRI during pregnancy Magnetic resonance imaging (MRI) If you are pregnant and ...

  14. Magnetic resonance apparatus

    DOEpatents

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

    1982-01-01

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

  15. Magnetically Tuned Spin Dynamics Resonance

    SciTech Connect

    Kronjaeger, J.; Becker, C.; Bongs, K.; Sengstock, K. [Institut fuer Laserphysik, Universitaet Hamburg, Luruper Chaussee 149, D-22761 Hamburg (Germany); Navez, P. [Labo Vaste-Stoffysica en Magnetisme, Katholieke Universiteit Leuven, Celestijnenlaan 200D, B-3001 Leuven (Belgium); additional address: Universitaet Duisburg-Essen, Universitaetsstrasse 5, 45117 Essen (Germany)

    2006-09-15

    We present the experimental observation of a magnetically tuned resonance phenomenon in the spin mixing dynamics of ultracold atomic gases. In particular, we study the magnetic field dependence of spin conversion in F=2 {sup 87}Rb spinor condensates in the crossover from interaction dominated to quadratic Zeeman dominated dynamics. We discuss the observations in the framework of spin dynamics as well as matter wave four wave mixing. Furthermore, we show that the validity range of the single mode approximation for spin dynamics is significantly extended at high magnetic field.

  16. Magnetically tuned spin dynamics resonance.

    PubMed

    Kronjäger, J; Becker, C; Navez, P; Bongs, K; Sengstock, K

    2006-09-15

    We present the experimental observation of a magnetically tuned resonance phenomenon in the spin mixing dynamics of ultracold atomic gases. In particular, we study the magnetic field dependence of spin conversion in F=2 (87)Rb spinor condensates in the crossover from interaction dominated to quadratic Zeeman dominated dynamics. We discuss the observations in the framework of spin dynamics as well as matter wave four wave mixing. Furthermore, we show that the validity range of the single mode approximation for spin dynamics is significantly extended at high magnetic field. PMID:17025866

  17. Magnetic resonance apparatus

    DOEpatents

    Jackson, J.A.; Cooper, R.K.

    1980-10-10

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

  18. Studies in nonlinear optics and functional magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Dai, Tehui

    There are two parts in this thesis. The first part will involve a study in the anomalous dispersion phase matched second-harmonic generation, and the second part will be a study in functional magnetic resonance imaging (fMRI) and a biophysical model of the human muscle. In part I, we report on a series of tricyanovinylaniline chromophores for use as dopants in poled poly(methyl methacrylate) waveguides for anomalous-dispersion phase- matched second-harmonic generation. Second-harmonic generation measurements as a function of mode index confirmed anomalous dispersion phase-matching efficiencies as large as 245%/Wcm2 over a propagation length of ~35 ?m. The waveguide coupling technique limited the interaction length. The photostability of the chromophores was measured directly and found to agree qualitatively with second-harmonic measurements over time and was found to be improved over previously reported materials. In part II, we designed a system that could record joint force and surface electromyography (EMG) simultaneously with fMRI data. I-Egh quality force and EMG data were obtained at the same time that excellent fMRI brain images were achieved. Using this system we determined the relationship between the fMRI-measured brain activation and the handgrip force, and between the fMRI-measured brain activation and the EMG of finger flexor muscles. We found that in the whole brain and in the majority of motor function-related cortical fields, the degree of muscle activation is directly proportional to the amplitude of the brain signal determined by the fMRI measurement. The similarity in the relationship between muscle output and fMRI signal in a number of brain areas suggests that multiple cortical fields are involved in controlling muscle force. The factors that may contribute to the fMRI signals are discussed. A biophysical twitch force model was developed to predict force response under electrical stimulation. Comparison between experimental and modeled force profiles, peak forces, and force duration shows excellent agreement between the model and the experimental data. It is concluded that the present model allows us to reproduce the main features of muscle activation under stimulation.

  19. Unentangling nuclear magnetic resonance Matthias Bechmann 1

    E-print Network

    Stepney, Susan

    Unentangling nuclear magnetic resonance computing Matthias Bechmann 1 , John A. Clark 2 , Angelika of York, UK, YO10 5DD Abstract. Nuclear magnetic resonance (NMR) is typically thought of as a possible computer sciences and nuclear magnetic resonance (NMR) spectroscopy have emerged. From the point of view

  20. Optimized design and analysis of sparse-sampling functional magnetic resonance imaging experiments of speech and hearing

    E-print Network

    Gabrieli, John

    of Brain & Cognitive Sciences, Massachusetts Institute of Technology 2 Research Laboratory of Electronics, Massachusetts Institute of Technology 3 Program in Speech and Hearing Biosciences and Technology, Harvard-MIT Division of Health Sciences and Technology Functional magnetic resonance imaging (fMRI) offers

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

    ERIC Educational Resources Information Center

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

    1998-01-01

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

  2. 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…

  3. The effects of antiepileptic drugs on cognitive functional magnetic resonance imaging

    PubMed Central

    Beltramini, Guilherme Coco; Cendes, Fernando

    2015-01-01

    The cognitive dysfunction caused by antiepileptic drugs (AEDs) has been extensively described, although the mechanisms underlying such collateral effects are still poorly understood. The combination of functional magnetic resonance imaging (fMRI) studies with pharmacological intervention (pharmaco-MRI or ph-MRI) offers the opportunity to investigate the effect of drugs such as AEDs on brain activity, including cognitive tasks. Here we review the studies that investigated the effects of AEDs [topiramate (TPM), lamotrigine (LMT), carbamazepine (CBZ), pregabalin (PGB), valproate (VPA) and levetiracetam (LEV)] on cognitive fMRI tasks. Despite the scarcity of fMRI studies focusing on the impact of AEDs on cognitive task, the results of recent work have provided important information about specific drug-related changes of brain function.

  4. Resonant magnetic fields from inflation

    SciTech Connect

    Byrnes, Christian T. [CERN, PH-TH Division, CH-1211, Genève 23 (Switzerland); Hollenstein, Lukas; Jain, Rajeev Kumar [Département de Physique Théorique and Center for Astroparticle Physics, Université de Genève, 24, Quai Ernest Ansermet, CH-1211 Genève 4 (Switzerland); Urban, Federico R., E-mail: cbyrnes@cern.ch, E-mail: lukas.hollenstein@unige.ch, E-mail: rajeev.jain@unige.ch, E-mail: urban@phas.ubc.ca [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, B.C. V6T 1Z1 (Canada)

    2012-03-01

    We propose a novel scenario to generate primordial magnetic fields during inflation induced by an oscillating coupling of the electromagnetic field to the inflaton. This resonant mechanism has two key advantages over previous proposals. First of all, it generates a narrow band of magnetic fields at any required wavelength, thereby allaying the usual problem of a strongly blue spectrum and its associated backreaction. Secondly, it avoids the need for a strong coupling as the coupling is oscillating rather than growing or decaying exponentially. Despite these major advantages, we find that the backreaction is still far too large during inflation if the generated magnetic fields are required to have a strength of O(10{sup ?15} Gauss) today on observationally interesting scales. We provide a more general no-go argument, proving that this problem will apply to any model in which the magnetic fields are generated on subhorizon scales and freeze after horizon crossing.

  5. Resonant magnetic fields from inflation

    E-print Network

    Christian T. Byrnes; Lukas Hollenstein; Rajeev Kumar Jain; Federico R. Urban

    2012-03-06

    We propose a novel scenario to generate primordial magnetic fields during inflation induced by an oscillating coupling of the electromagnetic field to the inflaton. This resonant mechanism has two key advantages over previous proposals. First of all, it generates a narrow band of magnetic fields at any required wavelength, thereby allaying the usual problem of a strongly blue spectrum and its associated backreaction. Secondly, it avoids the need for a strong coupling as the coupling is oscillating rather than growing or decaying exponentially. Despite these major advantages, we find that the backreaction is still far too large during inflation if the generated magnetic fields are required to have a strength of order 10^{-15} Gauss today on observationally interesting scales. We provide a more general no-go argument, proving that this problem will apply to any model in which the magnetic fields are generated on subhorizon scales and freeze after horizon crossing.

  6. In vivo static field perturbations in magnetic resonance

    NASA Astrophysics Data System (ADS)

    Koch, Kevin Matthew

    2007-12-01

    Fundamental magnetic resonance (MR) theory assumes the spatial homogeneity of a dominating static magnetic field B = B 0?. When this assumption is violated, a myriad of artifacts and compromising factors are introduced to MR spectra and images. Though in vivo nuclear magnetic resonance (NMR) is one of the most widely used scientific and diagnostic tools in medicine and biology, it remains haunted by the continual and persistant ghost of B0 inhomogeneity. An inclusive list of in vivo NMR applications severely impacted by B0 inhomogeneity could go on ad infinitum. Examples of such applications include neurosurgical utility in functional magnetic resonance imaging (fMRI), cerebral metabolic flux mapping, cerebral diffusion tractography, and abdominal diagnostic imaging. Given this wide impact on in vivo NMR, significant effort has been exerted in developing methods of compensating B0 inhomogeneity. Complicating this task is the sample-specific nature of in vivo B 0 inhomogeneity and its exacerbation with ever increasing B 0 field strengths. State of the art B 0 inhomogeneity compensation is currently at a critical juncture where homogenization demands are overwhelming the outer capabilities of existing technology and methods. This thesis addresses the B 0 inhomogeneity problem in the mammalian brain and presents novel solutions to the homogenization technology stalemate.

  7. 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.

  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. Comparison of data-driven analysis methods for identification of functional connectivity in fMRI

    E-print Network

    Kim, Yongwook Bryce

    2008-01-01

    Data-driven analysis methods, such as independent component analysis (ICA) and clustering, have found a fruitful application in the analysis of functional magnetic resonance imaging (fMRI) data for identifying functionally ...

  10. 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 ...

  11. 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 ...

  12. Neurophysiological investigation of the basis of the fMRI signal

    Microsoft Academic Search

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

    2001-01-01

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

  13. Localization of Cardiac-Induced Signal Change in fMRI

    Microsoft Academic Search

    Mandeep S. Dagli; John E. Ingeholm; James V. Haxby

    1999-01-01

    Signal detection in the analysis of blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI) may be greatly hindered by cardiac pulsatility artifacts. Vessel pulsation, cerebrospinal fluid movement, and tissue deformation are all associated with the cardiac cycle and all can produce fMRI signal variance. Most cognitive fMRI studies do not utilize a method of cardiac-related noise reduction, in part

  14. Quantitative nuclear magnetic resonance spectrometry

    Microsoft Academic Search

    Tareq Saed Al Deen; D Brynn Hibbert; James M Hook; Robert J Wells

    2002-01-01

    The purities of the widely-used herbicide glyphosate (N-(phosphonomethyl)glycine), and the insecticide profenofos (O-(4-bromo-2-chlorophenyl) O-ethyl S-propyl phosphorothioate) were determined by 1H and 31P quantitative nuclear magnetic resonance (QNMR) spectrometry using an internal standard. QNMR does not need a standard reference of the same target analyte, in contrast to chromatographic methods, but only a compound containing the nucleus of interest. Sodium acetate

  15. Interventional cardiovascular magnetic resonance imaging

    PubMed Central

    Raman, Venkatesh K.; Lederman, Robert J.

    2008-01-01

    Magnetic resonance imaging (MRI) provides structural and functional cardiovascular information with excellent soft tissue contrast. Real-time MRI can guide transcatheter cardiovascular interventions in large animal models, and may prove superior to x-ray and adjunct modalities for peripheral vascular, structural heart and cardiac electrophysiology applications. We describe technical considerations, pre-clinical work and early clinical studies in this emerging field. PMID:17662914

  16. Proceedings of the 2007 IEEE 10th International Conference on Rehabilitation Robotics, June 12-15, Noordwijk, The Netherlands MR_CHIROD v.2: A fMRI Compatible Mechatronic

    E-print Network

    Mavroidis, Constantinos

    -15, Noordwijk, The Netherlands MR_CHIROD v.2: A fMRI Compatible Mechatronic Hand Rehabilitation Device A. INTRODUCTION FUN CTIONAL magnetic resonance imaging (fMRI) has been widely used in studying human brain subjects. Therefore, fMRI compatible devices are required in order to study the motor performance

  17. Anisotropic 2D and 3D averaging of fMRI signals Andres Fco. Sol'e, ShingChung Ngan, Guillermo Sapiro, Xiaoping Hu, and Antonio L'opez

    E-print Network

    1 Anisotropic 2D and 3D averaging of fMRI signals Andres Fco. Sol'e, Shing­Chung Ngan, Guillermo proposed for comparing tem­ poral signals corresponding to active fMRI regions. Examples are presented both spectrum, signal metrics. I. Introduction Functional Magnetic Resonance Imaging (fMRI) is the most

  18. Four-Dimensional Compression of fMRI Using JPEG2000 Hariharan G. Lalgudi1, Ali Bilgin1, Michael W. Marcellin1, Ali Tabesh1, Mariappan S. Nadar2

    E-print Network

    Bilgin, Ali

    Four-Dimensional Compression of fMRI Using JPEG2000 Hariharan G. Lalgudi1, Ali Bilgin1, Michael W such technique is functional magnetic resonance imaging (fMRI) which aims to determine regions of the brain substantial resources for storage and transmission and hence call for efficient compression algorithms. fMRI

  19. 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

  20. NARX Neural Networks for Dynamical Modelling of fMRI Data

    Microsoft Academic Search

    Huaien Luo; Sadasivan Puthusserypady

    2006-01-01

    Functional magnetic resonance imaging (fMRI) is an important technique to study the human brain (the most complex biological dynamical system) functions which are often described by the hemodynamic responses (HDR). It measures the changes of the blood oxygenation level dependent (BOLD) signals due to the neural activities. The measured fMRI data is the response of the human brain to a

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

    Microsoft Academic Search

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

    1997-01-01

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

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

    Microsoft Academic Search

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

    2005-01-01

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

  3. Functional magnetic resonance imaging evidence of augmented pain processing in fibromyalgia

    Microsoft Academic Search

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

    2002-01-01

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

  4. Functional Magnetic Resonance Imaging Measures of the Effects of Morphine on Central Nervous System Circuitry in Opioid-Naive Healthy Volunteers

    Microsoft Academic Search

    Lino Becerra; Kim Harter; R. Gilberto Gonzalez; David Borsook

    2006-01-01

    In this pilot study, we used functional magnetic resonance imaging (fMRI) to study the effects of morphine in 8 healthy, opioid-naõ ¨ve volunteers. Intravenous small- dose morphine (4 mg\\/70 kg) or saline was administered to volunteers undergoing a fMRI scan. Infusion of morphine, but not saline, elicited mild euphoria without aversive symptoms and resulted in positive signal changes in reward

  5. Tracking Cognitive Change over 24 Weeks with Longitudinal Functional Magnetic Resonance Imaging in Alzheimer's Disease

    PubMed Central

    McLaren, Donald G.; Sreenivasan, Aishwarya; Diamond, Eli L.; Mitchell, Meghan B.; Van Dijk, Koene R.A.; DeLuca, Amy N.; O’Brien, Jacqueline L.; Rentz, Dorene M.; Sperling, Reisa A.; Atri, Alireza

    2012-01-01

    Background Previous studies have revealed that functional magnetic resonance imaging (fMRI) blood oxygen level-dependent (BOLD) signal in specific brain regions correlates with cross-sectional performance on standardized clinical trial measures in Alzheimer's disease (AD); however, the relationship between longitudinal change in fMRI-BOLD signal and neuropsychological performance remains unknown. Objective: To identify changes in regional fMRI-BOLD activity that tracks change in neuropsychological performance in mild AD dementia over 6 months. Methods Twenty-four subjects (mean age 71.6) with mild AD dementia (mean Mini Mental State Examination 21.7, Global Clinical Dementia Rating 1.0) on stable donepezil dosing participated in two task-related fMRI sessions consisting of a face-name paired associative encoding memory paradigm 24 weeks apart during a randomized placebo-controlled pharmaco-fMRI drug study. Regression analysis was used to identify regions where the change in fMRI activity for Novel > Repeated stimulus contrast was associated with the change scores on postscan memory tests and the Free and Cued Selective Reminding Test (FCSRT). Results Correlations between changes in postscan memory accuracy and changes in fMRI activity were observed in regions including the angular gyrus, parahippocampal gyrus, inferior frontal gyrus and cerebellum. Correlations between changes in FCSRT-free recall and changes in fMRI were observed in regions including the inferior parietal lobule, precuneus, hippocampus and parahippocampal gyrus. Conclusion Changes in encoding-related fMRI activity in regions implicated in mnemonic networks correlated with changes in psychometric measures of episodic memory retrieval performed outside the scanner. These exploratory results support the potential of fMRI activity to track cognitive change and detect signals of short-term pharmacologic effect in early-phase AD studies. PMID:22456451

  6. 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.

  7. Nuclear magnetic resonance in magnets with a spiral magnetic structure

    NASA Astrophysics Data System (ADS)

    Tankeyev, A. P.; Borich, M. A.; Smagin, V. V.

    2014-03-01

    Specific features of nuclear magnetic resonance (NMR) in a ferromagnet with a crystallographic magnetic anisotropy of the easy-plane type placed in a constant magnetic field have been studied. The symmetry of the magnet admits the existence of the Dzyaloshinskii-Moriya interaction, which leads to the formation of a new ground state, namely, a soliton lattice (spiral structure). Within the spin-wave approximation, the following basic local characteristics of the NMR of this structure have been calculated: resonance frequency, enhancement factor, and line broadening and their field dependences have been investigated. The magnetic resonance susceptibility of the electron-nucleus spin system has been calculated; the shape of the NMR absorption line has been analyzed. The problem of the evolution of the NMR absorption line upon the change in the magnitude of an external magnetic field has been solved. The possibility of the experimental detection and investigation of the structural and dynamic features of the spiral magnetic structure by the NMR method is discussed.

  8. 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.

  9. Magnetic resonance in an elliptic magnetic field

    E-print Network

    E. A. Ivanchenko

    2004-04-20

    The behaviour of a particle with a spin 1/2 and a dipole magnetic moment in a time-varying magnetic field in the form $(h_0 cn(\\omega t,k), h_0 sn(\\omega t,k), H_0 dn(\\omega t,k))$, where $\\omega$ is the driving field frequency, $t$ is the time, $h_0$ and $H_0$ are the field amplitudes, $cn$, $sn$, $dn$ are Jacobi elliptic functions, $ k$ is the modulus of the elliptic functions has been considered. The variation parameter $k$ from zero to 1 gives rise to a wide set of functions from trigonometric shapes to exponential pulse shapes modulating the field. The problem was reduced to the solution of general Heun' equation. The exact solution of the wave function was found at resonance for any $ k$. It has been shown that the transition probability in this case does not depend on $k$. The present study may be useful for analysis interference experiments, improving magnetic spectrometers and the field of quantum computing.

  10. 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

  11. Motion Estimation in Static Magnetic Resonance Elastography

    E-print Network

    Popel, Elena

    2009-12-09

    Elastography is the imaging of the biomechanical properties of a tissue to detect and diagnose abnormal pathologies in a variety of disease conditions. Static Magnetic Resonance Elastography (MRE) is a modality of elastography that uses Magnetic...

  12. 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

  13. Magnetic resonance imaging of radiation optic neuropathy

    SciTech Connect

    Zimmerman, C.F.; Schatz, N.J.; Glaser, J.S. (Univ. of Miami, FL (USA))

    1990-10-15

    Three patients with delayed radiation optic neuropathy after radiation therapy for parasellar neoplasms underwent magnetic resonance imaging. The affected optic nerves and chiasms showed enlargement and focal gadopentetate dimeglumine enhancement. The magnetic resonance imaging technique effectively detected and defined anterior visual pathway changes of radionecrosis and excluded the clinical possibility of visual loss because of tumor recurrence.

  14. 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.

  15. Chemical Principles Revisited. Proton Magnetic Resonance Spectroscopy.

    ERIC Educational Resources Information Center

    McQuarrie, Donald A.

    1988-01-01

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

  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. Quality Map Thresholding for De-noising of Complex-Valued fMRI Data and Its Application to ICA of fMRI.

    PubMed

    Rodriguez, Pedro A; Correa, Nicolle M; Eichele, Tom; Calhoun, Vince D; Adali, Tülay

    2009-09-01

    Although functional magnetic resonance imaging (fMRI) data are acquired as complex-valued images, traditionally most fMRI studies only use the magnitude of the data. FMRI analysis in the complex domain promises to provide more statistically significant information; however, the noisy nature of the phase poses a challenge for successful study of fMRI by complex-valued signal processing algorithms. In this paper, we introduce a physiologically motivated de-noising method that uses phase quality maps to successfully identify and eliminate noisy areas in the fMRI data so they can be used in individual and group studies. Additionally, we show how the developed de-noising method improves the results of complex-valued independent component analysis of fMRI data, a very successful tool for blind source separation of biomedical data. PMID:21949563

  18. 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

  19. 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

  20. [Research progress of brain functional magnetic resonance imaging in post-traumatic stress disorder].

    PubMed

    Wang, Ting; Zhang, Junran; Huang, Hua; Gong, Qiyong

    2014-06-01

    Post-traumatic stress disorder (PTSD) is a mental disorder causing great distress to individuals, families and even society, and there is not yet effective way of unified prevention and treatment up till now. Lots of neuroimaging techniques, however, such as the magnetic resonance imaging, are widely used to the study of the pathogenesis of PTSD with the development of medical imaging. Functional magnetic resonance imaging (fMRI) can be applied to detect the abnormalities not only of the brain morphology but also of the function of various cerebral areas and neural circuit, and plays an important role in studying the pathogenesis of psychiatric diseases. In this paper, we mainly review the task-related and resting-state functional magnetic resonance imaging studies of the PTSD, and finally suggest possible directions for future research. PMID:25219259

  1. Spread spectrum magnetic resonance imaging

    E-print Network

    Puy, Gilles; Gruetter, Rolf; Thiran, Jean-Philippe; Van De Ville, Dimitri; Vandergheynst, Pierre; Wiaux, Yves; 10.1109/TMI.2011.2173698

    2012-01-01

    We propose a novel compressed sensing technique to accelerate the magnetic resonance imaging (MRI) acquisition process. The method, coined spread spectrum MRI or simply s2MRI, consists of pre-modulating the signal of interest by a linear chirp before random k-space under-sampling, and then reconstructing the signal with non-linear algorithms that promote sparsity. The effectiveness of the procedure is theoretically underpinned by the optimization of the coherence between the sparsity and sensing bases. The proposed technique is thoroughly studied by means of numerical simulations, as well as phantom and in vivo experiments on a 7T scanner. Our results suggest that s2MRI performs better than state-of-the-art variable density k-space under-sampling approaches

  2. Magnetic resonance imaging of electrolysis.

    PubMed

    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

  3. 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

  4. Magnetic resonance elastography of abdomen.

    PubMed

    Venkatesh, Sudhakar Kundapur; Ehman, Richard L

    2015-04-01

    Many diseases cause substantial changes in the mechanical properties of tissue, and this provides motivation for developing methods to noninvasively assess the stiffness of tissue using imaging technology. Magnetic resonance elastography (MRE) has emerged as a versatile MRI-based technique, based on direct visualization of propagating shear waves in the tissues. The most established clinical application of MRE in the abdomen is in chronic liver disease. MRE is currently regarded as the most accurate noninvasive technique for detection and staging of liver fibrosis. Increasing experience and ongoing research is leading to exploration of applications in other abdominal organs. In this review article, the current use of MRE in liver disease and the potential future applications of this technology in other parts of the abdomen are surveyed. PMID:25488346

  5. Magnetic Resonance Imaging of Electrolysis.

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

    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.

  6. DEVELOPMENTAL NEUROIMAGING OF CHILDREN USING MAGNETIC RESONANCE TECHNIQUES

    E-print Network

    Stromswold, Karin

    DEVELOPMENTAL NEUROIMAGING OF CHILDREN USING MAGNETIC RESONANCE TECHNIQUES Michael J. Rivkin. Recently, powerful qualitative and quantita- tive magnetic resonance techniques have been developed, recent magnetic resonance imaging data related to human brain development during the fetal, neonatal

  7. Thomas T. Liu Center for Functional Magnetic Resonance Imaging

    E-print Network

    California at San Diego, University of

    Thomas T. Liu Center for Functional Magnetic Resonance Imaging University of California, San Diego Engineering, Stanford University 1999-2001 Postgraduate Researcher, Magnetic Resonance Physics Group for Functional Magnetic Resonance Imaging 2007-Present Associate Professor of Radiology and Bioengineering

  8. Quantification of Magnetic Resonance Spectroscopy signals with lineshape estimation

    E-print Network

    Quantification of Magnetic Resonance Spectroscopy signals with lineshape estimation M.I Osorio - ESAT-SCD, Katholieke Universiteit Leuven b Biomedical Nuclear - Magnetic Resonance Unit, Katholieke Universiteit Leuven Abstract Quantification of Magnetic Resonance Spectroscopy (MRS) signals is required

  9. Thomas T. Liu Center for Functional Magnetic Resonance Imaging

    E-print Network

    California at San Diego, University of

    Thomas T. Liu Center for Functional Magnetic Resonance Imaging University of California, San Diego Engineering, Stanford University 1999-2001 Postgraduate Researcher, Magnetic Resonance Physics Group for Functional Magnetic Resonance Imaging 2007-Present Associate Professor (with Tenure) of Radiology

  10. 21 CFR 892.1000 - Magnetic resonance diagnostic device.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 2010-04-01 false Magnetic resonance diagnostic device. 892... Diagnostic Devices § 892.1000 Magnetic resonance diagnostic device. (a) Identification. A magnetic resonance diagnostic device is...

  11. 76 FR 58281 - Magnetic Resonance Imaging Safety; Public Workshop

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-20

    ...Docket No. FDA-2011-N-0640] Magnetic Resonance Imaging Safety; Public Workshop...announcing a public workshop entitled: ``Magnetic Resonance Imaging (MRI) Safety Public...discuss factors affecting the safe use of magnetic resonance imaging (MRI) and...

  12. Extension of dVCA model and its application in estimating fMRI components

    NASA Astrophysics Data System (ADS)

    Zhang, Gaoyan; Zhang, Jiacai; Yao, Li; Zhao, Xiaojie

    2010-03-01

    General linear model (GLM) and independent component analysis (ICA) are widely used methods in the community of functional magnetic resonance imaging (fMRI) data analysis. GLM and ICA are all assuming that fMRI components are location locked. Here we extend the Differentially variable component analysis (dVCA) and introduce it into fMRI data to analyze the transient changes during fMRI experiments which are ignored in GLM and ICA. We apply the extended dVCA to model fMRI images as the linear combination of ongoing activity and multiple fMRI components. We test our extended dVCA method on simulated images that mimicked the fMRI slice images containing two components, and employ the iterative maximum a posteriori (MAP) solution succeed to estimate each component's time-invariant spatial patterns, and its time-variant amplitude scaling factors and location shifts. The extended dVCA algorithm also identify two fMRI components that reflect the fact of hemispheric asymmetry for motor area in another test with fMRI data acquired with the block design task of right/left hand finger tapping alternately. This work demonstrates that our extended dVCA method is robustness to detect the variability of the fMRI components that maybe existent during the fMRI experiments.

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

    PubMed Central

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

    2008-01-01

    Background It is generally believed that activation in functional magnetic resonance imaging (fMRI) is restricted to gray matter. Despite this, a number of studies have reported white matter activation, particularly when the corpus callosum is targeted using interhemispheric transfer tasks. These findings suggest that fMRI signals may not be neatly confined to gray matter tissue. In the current experiment, 4 T fMRI was employed to evaluate whether it is possible to detect white matter activation. We used an interhemispheric transfer task modelled after neurological studies of callosal disconnection. It was hypothesized that white matter activation could be detected using fMRI. Results Both group and individual data were considered. At liberal statistical thresholds (p < 0.005, uncorrected), group level activation was detected in the isthmus of the corpus callosum. This region connects the superior parietal cortices, which have been implicated previously in interhemispheric transfer. At the individual level, five of the 24 subjects (21%) had activation clusters that were located primarily within the corpus callosum. Consistent with the group results, the clusters of all five subjects were located in posterior callosal regions. The signal time courses for these clusters were comparable to those observed for task related gray matter activation. Conclusion The findings support the idea that, despite the inherent challenges, fMRI activation can be detected in the corpus callosum at the individual level. Future work is needed to determine whether the detection of this activation can be improved by utilizing higher spatial resolution, optimizing acquisition parameters, and analyzing the data with tissue specific models of the hemodynamic response. The ability to detect white matter fMRI activation expands the scope of basic and clinical brain mapping research, and provides a new approach for understanding brain connectivity. PMID:18789154

  14. 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

  15. Hosted by Yalin Wang Methods in Magnetic Resonance Imaging

    E-print Network

    Reisslein, Martin

    Hosted by Yalin Wang Methods in Magnetic Resonance Imaging Abstract: Magnetic Resonance Imaging for Magnetic Resonance in Medicine (ISMRM), and served on the ISMRM Board of Trustees and chaired their 20th Resonance Imaging and on the editorial boards of the journal Magnetic Resonance in Medicine. Dr. Pipe

  16. Emergency Information Center for Magnetic Resonance Research

    E-print Network

    Thomas, David D.

    Emergency Information for Center for Magnetic Resonance Research Dial 911 for Police, Fire Not Allow them to Enter the Magnet Room without being Screened and Briefed) Building: 180 Department. Remove subject from scanner and/or magnet room if possible (MR Safe wheelchair and gurney located in CTSI

  17. A Demonstration Model of Magnetic Resonance

    ERIC Educational Resources Information Center

    Sandhu, H. S.; Peemoeller, H.

    1974-01-01

    Describes a simple and inexpensive model to demonstrate the pulsed magnetic resonance phenomenon. Gives the details of construction of the device which can provide a direct demonstration of the precessional motion of a magnetic moment in a steady magnetic field. (Author/GS)

  18. 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

  19. GPU-based parallel group ICA for functional magnetic resonance data.

    PubMed

    Jing, Yanshan; Zeng, Weiming; Wang, Nizhuan; Ren, Tianlong; Shi, Yingchao; Yin, Jun; Xu, Qi

    2015-04-01

    The goal of our study is to develop a fast parallel implementation of group independent component analysis (ICA) for functional magnetic resonance imaging (fMRI) data using graphics processing units (GPU). Though ICA has become a standard method to identify brain functional connectivity of the fMRI data, it is computationally intensive, especially has a huge cost for the group data analysis. GPU with higher parallel computation power and lower cost are used for general purpose computing, which could contribute to fMRI data analysis significantly. In this study, a parallel group ICA (PGICA) on GPU, mainly consisting of GPU-based PCA using SVD and Infomax-ICA, is presented. In comparison to the serial group ICA, the proposed method demonstrated both significant speedup with 6-11 times and comparable accuracy of functional networks in our experiments. This proposed method is expected to perform the real-time post-processing for fMRI data analysis. PMID:25704870

  20. Functional magnetic resonance imaging reflects changes in brain functioning with sedation.

    PubMed

    Starbuck, Victoria N; Kay, Gary G; Platenberg, R. Craig; Lin, Chin-Shoou; Zielinski, Brandon A

    2000-12-01

    Functional magnetic resonance imaging (fMRI) studies have demonstrated localized brain activation during cognitive tasks. Brain activation increases with task complexity and decreases with familiarity. This study investigates how sleepiness alters the relationship between brain activation and task familiarity. We hypothesize that sleepiness prevents the reduction in activation associated with practice. Twenty-nine individuals rated their sleepiness using the Stanford Sleepiness Scale before fMRI. During imaging, subjects performed the Paced Auditory Serial Addition Test, a continuous mental arithmetic task. A positive correlation was observed between self-rated sleepiness and frontal brain activation. Fourteen subjects participated in phase 2. Sleepiness was induced by evening dosing with chlorpheniramine (CP) (8 mg or 12 mg) and terfenadine (60 mg) in the morning for 3 days before the second fMRI scan. The Multiple Sleep Latency Test (MSLT) was also performed. Results revealed a significant increase in fMRI activation in proportion to the dose of CP. In contrast, for all subjects receiving placebo there was a reduction in brain activation. MSLT revealed significant daytime sleepiness for subjects receiving CP. These findings suggest that sleepiness interferes with efficiency of brain functioning. The sleepy or sedated brain shows increased oxygen utilization during performance of a familiar cognitive task. Thus, the beneficial effect of prior task exposure is lost under conditions of sedation. Copyright 2000 John Wiley & Sons, Ltd. PMID:12404614

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

    PubMed Central

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

    2011-01-01

    Functional magnetic resonance imaging (fMRI) has become a popular technique for studies of human brain activity. Typically, fMRI is performed with >3-mm sampling, so that the imaging data can be regarded as two-dimensional samples that average through the 1.5—4-mm thickness of cerebral cortex. The increasing use of higher spatial resolutions, <1.5-mm sampling, complicates the analysis of fMRI, as one must now consider activity variations within the depth of the brain tissue. We present a set of surface-based methods to exploit the use of high-resolution fMRI for depth analysis. These methods utilize white-matter segmentations coupled with deformable-surface algorithms to create a smooth surface representation at the gray-white interface and pial membrane. These surfaces provide vertex positions and normals for depth calculations, enabling averaging schemes that can increase contrast-to-noise ratio, as well as permitting the direct analysis of depth profiles of functional activity in the human brain. PMID:22125419

  2. 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

  3. Functional cardiac magnetic resonance microscopy

    NASA Astrophysics Data System (ADS)

    Brau, Anja Christina Sophie

    2003-07-01

    The study of small animal models of human cardiovascular disease is critical to our understanding of the origin, progression, and treatment of this pervasive disease. Complete analysis of disease pathophysiology in these animal models requires measuring structural and functional changes at the level of the whole heart---a task for which an appropriate non-invasive imaging method is needed. The purpose of this work was thus to develop an imaging technique to support in vivo characterization of cardiac structure and function in rat and mouse models of cardiovascular disease. Whereas clinical cardiac magnetic resonance imaging (MRI) provides accurate assessment of the human heart, the extension of cardiac MRI from humans to rodents presents several formidable scaling challenges. Acquiring images of the mouse heart with organ definition and fluidity of contraction comparable to that achieved in humans requires an increase in spatial resolution by a factor of 3000 and an increase in temporal resolution by a factor of ten. No single technical innovation can meet the demanding imaging requirements imposed by the small animal. A functional cardiac magnetic resonance microscopy technique was developed by integrating improvements in physiological control, imaging hardware, biological synchronization of imaging, and pulse sequence design to achieve high-quality images of the murine heart with high spatial and temporal resolution. The specific methods and results from three different sets of imaging experiments are presented: (1) 2D functional imaging in the rat with spatial resolution of 175 mum2 x 1 mm and temporal resolution of 10 ms; (2) 3D functional imaging in the rat with spatial resolution of 100 mum 2 x 500 mum and temporal resolution of 30 ms; and (3) 2D functional imaging in the mouse with spatial resolution down to 100 mum2 x 1 mm and temporal resolution of 10 ms. The cardiac microscopy technique presented here represents a novel collection of technologies capable of acquiring routine high-quality images of murine cardiac structure and function with minimal artifacts and markedly higher spatial resolution compared to conventional techniques. This work is poised to serve a valuable role in the evaluation of cardiovascular disease and should find broad application in studies ranging from basic pathophysiology to drug discovery.

  4. Attenuation of the Neural Response to Sad Faces in Major Depression by Antidepressant Treatment: A Prospective, Event-Related Functional Magnetic Resonance Imaging Study

    Microsoft Academic Search

    Cynthia H. Y. Fu; Steven C. R. Williams; Anthony J. Cleare; Michael J. Brammer; Nicholas D. Walsh; Jieun Kim; Chris M. Andrew; Emilio Merlo Pich; Pauline M. Williams; Laurence J. Reed; Martina T. Mitterschiffthaler; John Suckling; Edward T. Bullmore

    2004-01-01

    Background: Depression is associated with interper- sonal difficulties related to abnormalities in affective fa- cial processing. Objectives: To map brain systems activated by sad fa- cial affect processing in patients with depression and to identify brain functional correlates of antidepressant treat- ment and symptomatic response. Design: Two groups underwent scanning twice using functional magnetic resonance imaging (fMRI) during an 8-week

  5. 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…

  6. Integrated measurement system for simultaneous functional magnetic resonance imaging and diffuse optical tomography in human brain mapping

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaofeng; Toronov, Vladislav Y.; Webb, Andrew G.

    2006-11-01

    An integrated measurement system has been developed for performing simultaneous functional magnetic resonance imaging (fMRI) and diffuse optical tomography (DOT) for human brain mapping experiments. The components of this system consist of a MRI-compatible multioverlapping-channel near-infrared (NIR) optical probe, techniques for accurate and reliable coregistration of optical and fMRI results, and an optical image reconstruction algorithm with structural and physiological constraints derived from the MRI data. The optical probe is fully MRI compatible in that it produces negligible MR image distortion and does not require any modification to the MRI scanner or data acquisition protocols. This probe can be attached to virtually any part of the head without imposing limits on optical data acquisition. Coregistration of images from fMRI and optical measurements is achieved by localizing the positions of the optical fibers using MRI markers. Human studies show successful implementation of the entire system.

  7. 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

  8. Artifacts in Magnetic Resonance Imaging

    PubMed Central

    Krupa, Katarzyna; Bekiesi?ska-Figatowska, Monika

    2015-01-01

    Summary 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.

  9. Cardiovascular magnetic resonance for amyloidosis.

    PubMed

    Fontana, Marianna; Chung, Robin; Hawkins, Philip N; Moon, James C

    2015-03-01

    Cardiac involvement drives the prognosis and treatment in systemic amyloid. Echocardiography, the mainstay of current cardiac imaging, defines cardiac structure and function. Echocardiography, in conjunction with clinical phenotype, electrocardiogram and biomarkers (brain natriuretic peptide and troponin), provides an assessment of the likelihood and extent of cardiac involvement. Two tests are transforming our understanding of cardiac amyloidosis, bone tracer scanning and cardiovascular magnetic resonance (CMR). CMR provides a "second opinion" on the heart's structure and systolic function with better accuracy and more precision than echocardiography but is unable to assess diastolic function and is not as widely available. Where CMR adds unique advantages is in evaluating myocardial tissue characterisation. With administration of contrast, the latest type of late gadolinium enhancement imaging (phase-sensitive inversion recovery sequence) is highly sensitive and specific with images virtually pathognomonic for amyloidosis. CMR is also demonstrating that the range of structural and functional changes in cardiac amyloid is broader than traditionally thought. CMR with T1 mapping, a relatively new CMR technique, can measure the amyloid burden and the myocyte response to infiltration (hypertrophy/cell loss) with advantages for tracking change (e.g. the wall thickness can stay the same but the composition can change) over time or during therapy. Such techniques hold great promise for advancing drug development in this arena and providing new prognostic insights. CMR with tissue characterisation is rewriting our understanding of cardiac amyloidosis and may lead to the development of new classification, therapies and prognostic systems. PMID:25549885

  10. Magnetic Resonance at Short Distances

    SciTech Connect

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

    2012-01-01

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

  11. 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

  12. Miniature Magnet for Electron Spin Resonance Experiments

    ERIC Educational Resources Information Center

    Rupp, L. W.; And Others

    1976-01-01

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

  13. Magnetic resonance imaging in cardiovascular disease 

    E-print Network

    Richards, Jennifer Margaret Jane

    2013-07-06

    Background Superparamagnetic particles of iron oxide (SPIO) are part of a novel and exciting class of ‘smart’ magnetic resonance imaging (MRI) contrast agents that are taken up by inflammatory cells. Ultrasmall SPIO ...

  14. Coronary Computed Tomography and Magnetic Resonance Imaging

    PubMed Central

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

    2009-01-01

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

  15. Parallel magnetic resonance imaging: characterization and comparison

    E-print Network

    Rane, Swati Dnyandeo

    2005-11-01

    Magnetic Resonance Imaging (MRI) is now increasingly being used for fast imaging applications such as real-time cardiac imaging, functional brain imaging, contrast enhanced MRI, etc. Imaging speed in MRI is mainly limited by different imaging...

  16. Magnetic moment of the Roper resonance

    E-print Network

    T. Bauer; J. Gegelia; S. Scherer

    2012-08-13

    The magnetic moment of the Roper resonance is calculated in the framework of a low-energy effective field theory of the strong interactions. A systematic power-counting procedure is implemented by applying the complex-mass scheme.

  17. Chronic liver disease: evaluation by magnetic resonance

    SciTech Connect

    Stark, D.D.; Goldberg, H.I.; Moss, A.A.; Bass, N.M.

    1984-01-01

    Magnetic resonance (MR) imaging distinguished hepatitis from fatty liver and cirrhosis in a woman with a history of alcohol abuse. Anatomic and physiologic manifestations of portal hypertension were also demonstrated by MR.

  18. Magnetic Resonance Imaging (MRI) (For Parents)

    MedlinePLUS

    KidsHealth > Parents > Cancer Center > Diagnostic Tests > Magnetic Resonance Imaging (MRI) Print A A A Text Size What's in this article? What It Is Why It's Done Preparation Procedure What to Expect ...

  19. Pocket atlas of cranial magnetic resonance imaging

    SciTech Connect

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

    1986-01-01

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

  20. Choledochocele: diagnosis by magnetic resonance imaging

    Microsoft Academic Search

    A. I. De Backer; K. Van den Abbeele; A. M. De Schepper; A. Van Baarle

    2000-01-01

    The value of magnetic resonance imaging (MRI) and magnetic resonance cholangiopancreatography (MRCP) is demonstrated in a\\u000a case of a 22-year-old female with a small choledochocele clinically presenting with acute cholecystitis and pancreatitis.\\u000a Previous abdominal sonography and computed tomography were not diagnostic. MRI and MRCP showed a cystic dilatation of the\\u000a distal common bile duct, intramurally located in the second portion

  1. 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.

  2. The Retinotopic Organization of Primate Dorsal V4 and Surrounding Areas: A Functional Magnetic Resonance Imaging Study in Awake Monkeys

    Microsoft Academic Search

    Denis Fize; Wim Vanduffel; Koen Nelissen; Katrien Denys; Christophe Chef d'Hotel; Olivier Faugeras; Guy A. Orban

    2003-01-01

    Using functional magnetic resonance imaging (fMRI), we mapped the retinotopic organization throughout the visual cortex of fixating monkeys. The retinotopy observed in areas V1, V2, and V3 was completely consistent with the classical view. V1 and V3 were bordered rostrally by a vertical meridian representation, and V2 was bordered by a horizontal meridian. More anterior in occipital cortex, both areas

  3. 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

  4. 4 Nuclear Magnetic Resonance and MRI February 26, 2008

    E-print Network

    Thouless, David

    4 Nuclear Magnetic Resonance and MRI February 26, 2008 The technique of nuclear magnetic resonance at Harvard, for which they both received the 1952 Physics Nobel Prize. Magnetic resonance methods have found of Magnetic Resonance Imaging (MRI) by Paul Lauter- bur, then at SUNY Stony Brook, and Peter Mansfield

  5. Ferromagnetic resonance in ?-Co magnetic composites.

    PubMed

    Chalapat, Khattiya; Timonen, Jaakko V I; Huuppola, Maija; Koponen, Lari; Johans, Christoffer; Ras, Robin H A; Ikkala, Olli; Oksanen, Markku A; Seppälä, Eira; Paraoanu, G S

    2014-12-01

    We investigate the electromagnetic properties of assemblies of nanoscale ?-cobalt crystals with size range between 5 to 35 nm, embedded in a polystyrene matrix, at microwave (1-12 GHz) frequencies. We investigate the samples by transmission electron microscopy imaging, demonstrating that the particles aggregate and form chains and clusters. By using a broadband coaxial-line method, we extract the magnetic permeability in the frequency range from 1 to 12 GHz, and we study the shift of the ferromagnetic resonance (FMR) with respect to an externally applied magnetic field. We find that the zero-magnetic field ferromagnetic resonant peak shifts towards higher frequencies at finite magnetic fields, and the magnitude of complex permeability is reduced. At fields larger than 2.5 kOe the resonant frequency changes linearly with the applied magnetic field, demonstrating the transition to a state in which the nanoparticles become dynamically decoupled. In this regime, the particles inside clusters can be treated as non-interacting, and the peak position can be predicted from Kittel's FMR theory for non-interacting uniaxial spherical particles combined with the Landau-Lifshitz-Gilbert equation. In contrast, at low magnetic fields this magnetic order breaks down and the resonant frequency in zero magnetic field reaches a saturation value reflecting the interparticle interactions as resulting from aggregation. Our results show that the electromagnetic properties of these composite materials can be tuned by external magnetic fields and by changes in the aggregation structure. PMID:25397945

  6. Ferromagnetic resonance in ?-Co magnetic composites

    NASA Astrophysics Data System (ADS)

    Chalapat, Khattiya; Timonen, Jaakko V. I.; Huuppola, Maija; Koponen, Lari; Johans, Christoffer; Ras, Robin H. A.; Ikkala, Olli; Oksanen, Markku A.; Seppälä, Eira; Paraoanu, G. S.

    2014-12-01

    We investigate the electromagnetic properties of assemblies of nanoscale ?-cobalt crystals with size range between 5 to 35 nm, embedded in a polystyrene matrix, at microwave (1–12 GHz) frequencies. We investigate the samples by transmission electron microscopy imaging, demonstrating that the particles aggregate and form chains and clusters. By using a broadband coaxial-line method, we extract the magnetic permeability in the frequency range from 1 to 12 GHz, and we study the shift of the ferromagnetic resonance (FMR) with respect to an externally applied magnetic field. We find that the zero-magnetic field ferromagnetic resonant peak shifts towards higher frequencies at finite magnetic fields, and the magnitude of complex permeability is reduced. At fields larger than 2.5 kOe the resonant frequency changes linearly with the applied magnetic field, demonstrating the transition to a state in which the nanoparticles become dynamically decoupled. In this regime, the particles inside clusters can be treated as non-interacting, and the peak position can be predicted from Kittel?s FMR theory for non-interacting uniaxial spherical particles combined with the Landau–Lifshitz–Gilbert equation. In contrast, at low magnetic fields this magnetic order breaks down and the resonant frequency in zero magnetic field reaches a saturation value reflecting the interparticle interactions as resulting from aggregation. Our results show that the electromagnetic properties of these composite materials can be tuned by external magnetic fields and by changes in the aggregation structure.

  7. Multispectral magnetic resonance image analysis.

    PubMed

    Vannier, M W; Butterfield, R L; Rickman, D L; Jordan, D M; Murphy, W A; Biondetti, P R

    1987-01-01

    Multiecho magnetic resonance (MR) scanning produces tomographic images with approximately equal morphologic information but varying gray scales at the same anatomic level. Multispectral image classification techniques, originally developed for satellite imaging, have recently been applied to MR tissue characterization. Statistical assessment of multispectral tissue classification techniques has been used to select the most promising of several alternative methods. MR examinations of the head and body, obtained with a 0.35, 0.5, or 1.5T imager, comprised data sets with at least two pulse sequences yielding three images at each anatomical level: (1) TR = 0.3 sec, TE = 30 msec, (2) TR = 1.5, TE = 30, (3) TR = 1.5, TE = 120. Normal and pathological images have been analyzed using multispectral analysis and image classification. MR image data are first subjected to radiometric and geometric corrections to reduce error resulting from (1) instrumental variations in data acquisition, (2) image noise, and (3) misregistration. Training regions of interest (ROI) are outlined in areas of normal (gray and white matter, CSF) and pathological tissue. Statistics are extracted from these ROIs and classification maps generated using table lookup, minimum distance to means, maximum likelihood, and cluster analysis. These synthetic maps are then compared pixel by pixel with manually prepared classification maps of the same MR images. Using these methods, the authors have found that: (1) both supervised and unsupervised classification techniques yielded theme maps (class maps) which demonstrated tissue characteristic signatures and (2) tissue classification errors found in computer-generated theme maps were due to subtle gray scale changes present in the original MR data sets arising from radiometric inhomogeneity and spatial nonuniformity. PMID:3691157

  8. “Calm Down Dear, It’s Only a Simulator.” An investigation into the effects of the fMRI environment on cognition. 

    E-print Network

    Black, Ashley Anne

    2007-01-01

    Functional Magnetic Resonance Imaging (fMRI) is a useful tool which permits the observation of the brain’s neuronal activity in a non-invasive, on-line manner. The usefulness of the technique has however been questioned ...

  9. 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

  10. PTFOS: flexible and absorbable intracranial electrodes for magnetic resonance imaging.

    PubMed

    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

  11. Ferromagnetic resonance imaging of Co films using magnetic resonance force microscopy

    E-print Network

    Hammel, P. Chris

    Ferromagnetic resonance imaging of Co films using magnetic resonance force microscopy B. J. Suh, P of microscopic ferromagnetic resonance FMR detected using the magnetic resonance force microscope MRFM of structural and magnetic properties of materials. The mag- netic resonance force microscope MRFM can

  12. Sensitivity and spatial resolution for electron-spin-resonance detection by magnetic resonance force microscopy

    E-print Network

    Hammel, P. Chris

    Sensitivity and spatial resolution for electron-spin-resonance detection by magnetic resonance The signal intensity of electron spin resonance in magnetic resonance force microscopy MRFM experiments that magnetic resonance force microscopy MRFM is a new 3D imaging technique8,9 with the potential of achieving

  13. Fano resonances in magnetic metamaterials

    SciTech Connect

    Naether, Uta; Molina, Mario I. [Departmento de Fisica, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago (Chile) and Center for Optics and Photonics (CEFOP), Casilla 4016, Concepcion (Chile)

    2011-10-15

    We study the scattering of magnetoinductive plane waves by internal (external) capacitive (inductive) defects coupled to a one-dimensional split-ring resonator array. We examine a number of simple defect configurations where Fano resonances occur and study the behavior of the transmission coefficient as a function of the controllable external parameters. We find that for embedded capacitive defects, the addition of a small amount of coupling to second neighbors is necessary for the occurrence of Fano resonance. For external inductive defects, Fano resonances are commonplace, and they can be tuned by changing the relative orientation or distance between the defect and the SSR array.

  14. Investigating emotion with music: An fMRI study

    Microsoft Academic Search

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

    2006-01-01

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

  15. 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…

  16. 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

  17. 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…

  18. Pharmacological fMRI; a clinical exploration

    Microsoft Academic Search

    R. Goekoop

    2006-01-01

    Dit proefschrift beschrijft de resultaten van een verkennend onderzoek naar een nieuwe techniek die gebruikt kan worden om de effecten van geneesmiddelen op hersenaktiviteit af te beelden: pharmacologische functionele magnetic resonance imaging (farmacologische fMRI of phMRI). Met behulp van deze techniek werden de effecten onderzocht van drie verschillende medicijnen (de bètablokker propranolol, de selectieve oestrogeen-receptor modulator (SERM) raloxifene en de

  19. Observation of ferromagnetic resonance in a microscopic sample using magnetic resonance force microscopy

    E-print Network

    Hammel, P. Chris

    Observation of ferromagnetic resonance in a microscopic sample using magnetic resonance force can be measured. Employing magnetic resonance force microscopy MRFM we have observed a strong FMR the technologically important magnetic multilayer systems. MRFM, based on mechanical detection of magnetic resonance

  20. Coherence of magnetic resonators in a metamaterial

    SciTech Connect

    Hou, Yumin, E-mail: ymhou@pku.edu.cn [State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871 (China)] [State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871 (China)

    2013-12-15

    The coherence of periodic magnetic resonators (MRs) under oblique incidence is studied using simulations. The correlated phase of interaction including both the retardation effect and relative phase difference between two MRs is defined, and it plays a key role in the MR interaction. The correlated phase is anisotropic, as is the coherence condition. The coherence condition is the same as the Wood's anomaly and verified by the Fano resonance. This study shows that the applications of the Fano resonance of periodic MRs will become widespread owing to achieving the Fano resonance simply by tuning the incident angle.

  1. 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.

  2. Nuclear Magnetic Resonance Technology for Medical Studies

    NASA Astrophysics Data System (ADS)

    Budinger, Thomas F.; Lauterbur, Paul C.

    1984-10-01

    Nuclear magnetic resonance proton imaging provides anatomical definition of normal and abnormal tissues with a contrast and detection sensitivity superior to those of x-ray computed tomography in the human head and pelvis and parts of the cardiovascular and musculoskeletal systems. Recent improvements in technology should lead to advances in diagnostic imaging of the breast and regions of the abdomen. Selected-region nuclear magnetic resonance spectroscopy of protons, carbon-13, and phosphorus-31 has developed into a basic science tool for in vivo studies on man and a unique tool for clinical diagnoses of metabolic disorders. At present, nuclear magnetic resonance is considered safe if access to the magnet environment is controlled. Technological advances employing field strengths over 2 teslas will require biophysical studies of heating and static field effects.

  3. Comparison of magnetic resonance angiography, magnetic resonance imaging and conventional angiography in cerebral arteriovenous malformation

    Microsoft Academic Search

    F. Nüssel; H. Wegmüller; P. Huber

    1991-01-01

    10 patients with an AVM of the brain were examined by magnetic resonance angiography (MRA), magnetic resonance imaging (MRI) and conventional cerebral angiography (CCA). From MRA in 7\\/10 patients important information about vascular supply could be provided; in 3 patients, all with small AVM's it could be only suspected. CCA revealed the vascularisation of the AVM's in all patients and

  4. 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

  5. Inferring visual system connectivity using dynamic causal modeling of functional magnetic resonance imaging data

    NASA Astrophysics Data System (ADS)

    Mahroos, Ashraf M.; Kadah, Yasser M.

    2010-03-01

    One of the recent themes to study the brain dynamics is studying the effective connectivity between brain regions in the target area. We propose and apply algorithm model, dynamic causal modeling (DCM), Psychophysiological interaction (PPI) and first order kernels and also SVD applied directly to singular intrinsic connectivity matrix end up to integrate and describe the interaction of several Brain Regions based on functional magnetic resonance imaging time series to make inferences about functional integration and segregation within the human brain. The method is to demonstrate using real data to show how such models are able to characterize interregional dependence. We extend estimating and reviewing designed model to characterize the interactions between regions and then to estimate the effective connectivity between these regions. All designs, estimates, reviews are implemented using SPM, one of the free best software packages used for design models and analysis for inferring about FMRI functional magnetic resonance imaging time series.

  6. Magnetic resonance imaging by using nano-magnetic particles

    NASA Astrophysics Data System (ADS)

    Shokrollahi, H.; Khorramdin, A.; Isapour, Gh.

    2014-11-01

    Magnetism and magnetic materials play a major role in various biological applications, such as magnetic bioseparation, magnetic resonance imaging (MRI), hyperthermia treatment of cancer and drug delivery. Among these techniques, MRI is a powerful method not only for diagnostic radiology but also for therapeutic medicine that utilizes a magnetic field and radio waves. Recently, this technique has contributed greatly to the promotion of the human quality life. Thus, this paper presents a short review of the physical principles and recent advances of MRI, as well as providing a summary of the synthesis methods and properties of contrast agents, like different core materials and surfactants.

  7. Magnetic resonance of magnetic fluid and magnetoliposome preparations

    NASA Astrophysics Data System (ADS)

    Morais, Paulo C.; Santos, Judes G.; Skeff Neto, K.; Pelegrini, Fernando; De Cuyper, Marcel

    2005-05-01

    In this study, magnetic resonance was used to investigate lauric acid-coated magnetite-based magnetic fluid particles and particles which are surrounded by a double layer of phospholipid molecules (magnetoliposomes). The data reveal the presence of monomers and dimers in both samples. Whereas evidence for a thermally induced disruption of dimers is found in the magnetic fluid, apparently, the bilayer phospholipid envelop prevents the dissociation in the magnetoliposome samples.

  8. 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.

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

    PubMed

    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. PMID:25700116

  10. Nuclear magnetic resonance offers new insights into Pu 239

    E-print Network

    - 1 - Nuclear magnetic resonance offers new insights into Pu 239 May 29, 2012 Nuclear magnetic signal of plutonium 239's unique nuclear magnetic resonance signature has been detected by scientists on the subject, "Observation of 239 Pu Nuclear Magnetic Resonance," was published in the May 18 issue of Science

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

    Microsoft Academic Search

    Roberto Cabeza; Lars Nyberg

    2000-01-01

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

  12. 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

  13. 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

  14. Non-white noise in fMRI: Does modelling have an impact?

    Microsoft Academic Search

    Torben E. Lund; Kristoffer H. Madsen; Karam Sidaros; Wen-Lin Luo; Thomas E. Nichols

    2006-01-01

    The sources of non-white noise in Blood Oxygenation Level Dependent (BOLD) functional magnetic resonance imaging (fMRI) are many. Familiar sources include low-frequency drift due to hardware imperfections, oscillatory noise due to respiration and cardiac pulsation and residual movement artefacts not accounted for by rigid body registration. These contributions give rise to temporal autocorrelation in the residuals of the fMRI signal

  15. Anatomic Localization and Quantitative Analysis of Gradient Refocused Echo-Planar fMRI Susceptibility Artifacts

    Microsoft Academic Search

    Jeffrey G. Ojemann; Erbil Akbudak; Abraham Z. Snyder; Robert C. McKinstry; Marcus E. Raichle; Thomas E. Conturo

    1997-01-01

    Functional magnetic resonance imaging (fMRI) techniques, such as echo-planar imaging, can permit rapid, sensitive, whole-brain measurements of local blood flow-induced MR signal changes seen during cognitive paradigms. Changes in blood oxygenation due to mismatch of flow and oxygen metabolism cause dynamic variations in microscopic susceptibility effects, leading to the blood oxygenation level-dependent (BOLD) signal measured by fMRI techniques. A related

  16. Analysis of fMRI data by blind separation into independent spatial components

    Microsoft Academic Search

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

    1998-01-01

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

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

    Microsoft Academic Search

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

    2000-01-01

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

  18. 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

  19. Applications of Cardiac Magnetic Resonance in Electrophysiology

    PubMed Central

    Nazarian, Saman; Bluemke, David A.; Halperin, Henry R.

    2012-01-01

    Contemporary methods for evaluation and treatment of arrhythmia are increasingly dependent upon characterization of the underlying myocardial substrate. Cardiovascular magnetic resonance offers unsurpassed soft tissue resolution capable of visualizing detailed cardiac anatomic features and intra-myocardial barriers to conduction. Non-invasive visualization of such anatomic detail has the potential to improve methods to diagnose, risk stratify, and treat patients with arrhythmia. This review describes a brief overview of the current knowledge on the applications of cardiac magnetic resonance for evaluation and treatment of patients with arrhythmia. PMID:19808444

  20. Granular convection observed by magnetic resonance imaging

    SciTech Connect

    Ehrichs, E.E.; Jaeger, H.M.; Knight, J.B.; Nagel, S.R.; Karczmar, G.S.; Kuperman, V.Yu. [Univ. of Chicago, IL (United States)

    1995-03-17

    Vibrations in a granular material can spontaneously produce convection rolls reminiscent of those seen in fluids. Magnetic resonance imaging provides a sensitive and noninvasive probe for the detection of these convection currents, which have otherwise been difficult to observe. A magnetic resonance imaging study of convection in a column of poppy seeds yielded data about the detailed shape of the convection rolls and the depth dependence of the convection velocity. The velocity was found to decrease exponentially with depth; a simple model for this behavior is presented here. 31 refs., 4 figs.

  1. Granular convection observed by magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

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

    1995-03-01

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

  2. MAGNETIC RESONANCE IN CHEMISTRY Magn. Reson. Chem. 2006; 44: S206S212

    E-print Network

    Wider, Gerhard

    MAGNETIC RESONANCE IN CHEMISTRY Magn. Reson. Chem. 2006; 44: S206­S212 Published online in Wiley 16 March 2006 Sample concentrations can be measured by nuclear magnetic resonance (NMR) spectroscopy Quantitative nuclear magnetic resonance (NMR) is an efficient method for the determination of concentrations

  3. Magnetic force microscopy using tip magnetization modulated by ferromagnetic resonance

    NASA Astrophysics Data System (ADS)

    Arima, Eiji; Naitoh, Yoshitaka; Li, Yan Jun; Yoshimura, Satoru; Saito, Hitoshi; Nomura, Hikaru; Nakatani, Ryoichi; Sugawara, Yasuhiro

    2015-03-01

    In magnetic force microscopy (MFM), the tip–sample distance should be reduced to analyze the microscopic magnetic domain structure with high spatial resolution. However, achieving a small tip–sample distance has been difficult because of superimposition of interaction forces such as van der Waals and electrostatic forces induced by the sample surface. In this study, we propose a new method of MFM using ferromagnetic resonance (FMR) to extract only the magnetic field near the sample surface. In this method, the magnetization of a magnetic cantilever is modulated by FMR to separate the magnetic field and topographic structure. We demonstrate the modulation of the magnetization of the cantilever and the identification of the polarities of a perpendicular magnetic medium.

  4. Magnetic Resonance Imaging (MRI) - Spine

    MedlinePLUS

    ... the magnet, radio waves redirect alignment of hydrogen atoms that naturally exist within the body without causing ... chemical changes in the tissues. As the hydrogen atoms return to their usual alignment, they emit energy ...

  5. Magnetic elliptical polarization of Schumann resonances

    NASA Technical Reports Server (NTRS)

    Sentman, D. D.

    1987-01-01

    Measurements of orthogonal, horizontal components of the magnetic field in the ELF range obtained during September 1985 show that the Schumann resonance eigenfrequencies determined separately for the north-south and east-west magnetic components differ by as much as 0.5 Hz, suggesting that the underlying magnetic signal is not linearly polarized at such times. The high degree of magnetic ellipticity found suggests that the side multiplets of the Schumann resonances corresponding to azimuthally inhomogeneous normal modes are strongly excited in the highly asymmetric earth-ionosphere cavity. The dominant sense of polarization over the measurement passband is found to be right-handed during local daylight hours, and to be left-handed during local nighttime hours.

  6. JOURNAL OF MAGNETIC RESONANCE 99,495-506 ( 1992) Sensitivity of Optically Excited andDetectedMagnetic Resonance

    E-print Network

    Suter, Dieter

    JOURNAL OF MAGNETIC RESONANCE 99,495-506 ( 1992) Sensitivity of Optically Excited andDetectedMagnetic forms of spectroscopy, the sensitivity of magnetic resonance exper- iments is relatively low, so some of this sensitivity advantage to the domain of magnetic resonance and gives numerical estimates

  7. A functional magnetic resonance imaging study on the neural mechanisms of hyperalgesic nocebo effect.

    PubMed

    Kong, Jian; Gollub, Randy L; Polich, Ginger; Kirsch, Irving; Laviolette, Peter; Vangel, Mark; Rosen, Bruce; Kaptchuk, Ted J

    2008-12-01

    Previous studies suggest that nocebo effects, sometimes termed "negative placebo effects," can contribute appreciably to a variety of medical symptoms and adverse events in clinical trials and medical care. In this study, using a within-subject design, we combined functional magnetic resonance imaging (fMRI) and an expectation/conditioning manipulation model to investigate the neural substrates of nocebo hyperalgesia using heat pain on the right forearm. Thirteen subjects completed the study. Results showed that, after administering inert treatment, subjective pain intensity ratings increased significantly more on nocebo regions compared with the control regions in which no expectancy/conditioning manipulation was performed. fMRI analysis of hyperalgesic nocebo responses to identical calibrated noxious stimuli showed signal increases in brain regions including bilateral dorsal anterior cingulate cortex (ACC), insula, superior temporal gyrus; left frontal and parietal operculum, medial frontal gyrus, orbital prefrontal cortex, superior parietal lobule, and hippocampus; right claustrum/putamen, lateral prefrontal gyrus, and middle temporal gyrus. Functional connectivity analysis of spontaneous resting-state fMRI data from the same cohort of subjects showed a correlation between two seed regions (left frontal operculum and hippocampus) and pain network including bilateral insula, operculum, ACC, and left S1/M1. In conclusion, we found evidence that nocebo hyperalgesia may be predominantly produced through an affective-cognitive pain pathway (medial pain system), and the left hippocampus may play an important role in this process. PMID:19052227

  8. 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

  9. Video: Proton Nuclear Magnetic Resonance (NMR)

    NSDL National Science Digital Library

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

  10. Development of a simple pressure and heat stimulator for intra- and interdigit functional magnetic resonance imaging.

    PubMed

    Kim, Hyung-Sik; Choi, Mi-Hyun; Kim, Hyun-Joo; Hong, Sang-Pyo; Park, Jang-Yeon; Jun, Jae-Hoon; Yi, Jeong-Han; Chung, Yoon-Gi; Kim, Sung-Phil; Park, Jong-Rak; Lim, Dae-Woon; Chung, Soon-Cheol

    2014-06-01

    For this study, we developed a simple pressure and heat stimulator that can quantitatively control pressure and provide heat stimulation to intra- and interdigit areas. The developed stimulator consists of a control unit, drive units, and tactors. The control unit controls the stimulation parameters, such as stimulation types, intensity, time, and channel, and transmits a created signal of stimulation to the drive units. The drive units operate pressure and heat tactors in response to commands from the control unit. The pressure and heat tactors can display various stimulation intensities quantitatively, apply stimulation continuously, and adjust the stimulation areas. Additionally, they can easily be attached to and detached from the digits. The developed pressure and heat stimulator is small in total size, easy to install, and inexpensive to manufacture. The new stimulator operated stably in a magnetic resonance imaging (MRI) environment without affecting the obtained images. A preliminary functional magnetic resonance imaging (fMRI) experiment confirmed that differences in activation of somatosensory areas were induced from the pressure and heat stimulation. The developed pressure and heat stimulator is expected to be utilized for future intra- and interdigit fMRI studies on pressure and heat stimulation. PMID:23861087

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

    NASA Astrophysics Data System (ADS)

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

    2004-05-01

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

  13. Magnetic resonance imaging of the knee

    Microsoft Academic Search

    D. W. Jackson; L. D. Jennings; R. M. Maywood; P. E. Berger

    1988-01-01

    Magnetic resonance imaging (MRI) is an accepted non invasive modality for evaluation of soft tissue pathology without exposure to ionizing radiation. Current appli cations demonstrate excellent visualization of the anat omy and pathology of various organs. Preliminary stud ies in the knee reveal fine resolution of anatomy and pathology involving the meniscus. The purpose of this study is to determine

  14. Magnetic Resonance Connectome Automated Pipeline: An Overview

    Microsoft Academic Search

    William R. Gray; John A. Bogovic; Joshua T. Vogelstein; Bennett A. Landman; Jerry L. Prince; R. Jacob Vogelstein

    2012-01-01

    This article presents a novel, tightly integrated pipeline for estimating a connectome. The pipeline utilizes magnetic resonance (MR) imaging (MRI) data to produce a high-level estimate of the structural connectivity in the human brain. The MR connectome automated pipeline (MRCAP) is efficient, and its modular construction allows researchers to modify algorithms to meet their specific requirements. The pipeline has been

  15. Imaging Intelligence with Proton Magnetic Resonance Spectroscopy

    ERIC Educational Resources Information Center

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

    2009-01-01

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

  16. Magnetic resonance imaging in cancer research

    Microsoft Academic Search

    B. D. Ross; T. L. Chenevert; A. Rehemtulla

    2002-01-01

    Non-invasive assessment of antineoplastic response and correlation of the location, magnitude and duration of transgene expression in vivo would be particularly useful for evaluating cancer gene therapy protocols. This review presents selected examples of how magnetic resonance (MR) has been used to assess therapeutic efficacy by non-invasive quantitation of cell kill, to detect a therapeutic response prior to a change

  17. Magnetic Resonance Imaging of the Elbow

    Microsoft Academic Search

    C. Chung; L. Steinbach

    Elbow injuries are common, especially in the athlete, and can be basically classified into acute or chronic injuries. The\\u000a following discussion of magnetic resonance imaging (MRI) of the elbow will address variations in normal anatomy that represent\\u000a pitfalls in imaging diagnosis, and commonly encountered osseous and soft-tissue pathology.

  18. Functional Magnetic Resonance Imaging of Pain Consciousness

    E-print Network

    Apkarian, A. Vania

    clinical pain states can be studied. Preliminary results are shown in patients suffering from chronicFunctional Magnetic Resonance Imaging of Pain Consciousness: Cortical Networks of Pain Critically Depend on What is Implied by "Pain" A. Vania Apkarian, PhD Address SUNY Health Science Center, Department

  19. 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.

  20. 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

  1. Nuclear magnetic resonance technology for medical studies

    Microsoft Academic Search

    T. F. Budinger; P. C. Lauterbur

    1984-01-01

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

  2. Magnetic Resonance Imaging of the Postoperative Meniscus

    Microsoft Academic Search

    Kennan Vance; Richard Meredick; Mark E. Schweitzer; James H. Lubowitz

    2009-01-01

    Imaging of the postoperative meniscus is a challenge. Nevertheless, magnetic resonance imaging (MRI) of the symptomatic knee after meniscal surgery is a valuable diagnostic study of both the menisci and the entire joint. At present, symptomatic patients who have had partial meniscectomy of less than 25% may be evaluated by MRI. For those with partial meniscectomy of greater than 25%

  3. Cine magnetic resonance imaging of aqueductal stenosis

    Microsoft Academic Search

    Chikafusa Kadowaki; Mitsuhiro Hara; Mitsuo Numoto; Kazuo Takeuchi; Isamu Saito

    1995-01-01

    Cerebral aqueductal stenosis is one of the most common causes of congenital and acquired hydrocephalus, but the etiology, pathophysiology and cerebrospinal fluid (CSF) dynamics of aqueductal stenosis have yet to be clarified. Utilizing cardiac gated cine magnetic resonance (MR) imaging, we evaluated aqueductal configuration and pulsatile motion of brain and CSF flow stimulated by cardiac pulsation in five patients with

  4. The diabetic foot: magnetic resonance imaging evaluation

    Microsoft Academic Search

    Javier Beltran; D. Scott Campanini; Charles Knight; Melinda McCalla

    1990-01-01

    Fourteen diabetic patients with suspected foot infection and\\/or neuropathic joint (Charcot Joint) were evaluated with magnetic resonance imaging (MRI) in an attempt to assess the extent of the infection and also to distinguish infection from the changes seen with neuroarthropathy. The majority of patients with infection had more than one site of involvement and the following diagnoses were made by

  5. Magnetic resonance imaging in motor neuron disease

    Microsoft Academic Search

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

    1990-01-01

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

  6. Brain Morphometry Using Anatomical Magnetic Resonance Imaging

    ERIC Educational Resources Information Center

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

    2008-01-01

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

  7. 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.

  8. Quantum electrodynamic equations for magnetic resonance- and optical spectroscopic transitions

    E-print Network

    D. Yearchuck; Y. Yerchak; A. Alexandrov

    2009-03-02

    Quantum electrodynamic equations for magnetic resonance- and optical spectroscopic transitions have been for the first time obtained. New phenomena - stochastic electrical and magnetic spin wave resonances are predicted to be the effects of EM-field quantization.

  9. 21 CFR 892.1000 - Magnetic resonance diagnostic device.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...distribution and/or magnetic resonance spectra which reflect frequency and distribution of nuclei exhibiting nuclear magnetic resonance. Other physical parameters derived from the images and/or spectra may also be produced. The...

  10. 21 CFR 892.1000 - Magnetic resonance diagnostic device.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...distribution and/or magnetic resonance spectra which reflect frequency and distribution of nuclei exhibiting nuclear magnetic resonance. Other physical parameters derived from the images and/or spectra may also be produced. The...

  11. 21 CFR 892.1000 - Magnetic resonance diagnostic device.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...distribution and/or magnetic resonance spectra which reflect frequency and distribution of nuclei exhibiting nuclear magnetic resonance. Other physical parameters derived from the images and/or spectra may also be produced. The...

  12. 21 CFR 892.1000 - Magnetic resonance diagnostic device.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...distribution and/or magnetic resonance spectra which reflect frequency and distribution of nuclei exhibiting nuclear magnetic resonance. Other physical parameters derived from the images and/or spectra may also be produced. The...

  13. Establishing the resting state default mode network derived from functional magnetic resonance imaging tasks as an endophenotype: A twins study.

    PubMed

    Korgaonkar, Mayuresh S; Ram, Kaushik; Williams, Leanne M; Gatt, Justine M; Grieve, Stuart M

    2014-08-01

    The resting state default mode network (DMN) has been shown to characterize a number of neurological and psychiatric disorders. Evidence suggests an underlying genetic basis for this network and hence could serve as potential endophenotype for these disorders. Heritability is a defining criterion for endophenotypes. The DMN is measured either using a resting-state functional magnetic resonance imaging (fMRI) scan or by extracting resting state activity from task-based fMRI. The current study is the first to evaluate heritability of this task-derived resting activity. 250 healthy adult twins (79 monozygotic and 46 dizygotic same sex twin pairs) completed five cognitive and emotion processing fMRI tasks. Resting state DMN functional connectivity was derived from these five fMRI tasks. We validated this approach by comparing connectivity estimates from task-derived resting activity for all five fMRI tasks, with those obtained using a dedicated task-free resting state scan in an independent cohort of 27 healthy individuals. Structural equation modeling using the classic twin design was used to estimate the genetic and environmental contributions to variance for the resting-state DMN functional connectivity. About 9-41% of the variance in functional connectivity between the DMN nodes was attributed to genetic contribution with the greatest heritability found for functional connectivity between the posterior cingulate and right inferior parietal nodes (P<0.001). Our data provide new evidence that functional connectivity measures from the intrinsic DMN derived from task-based fMRI datasets are under genetic control and have the potential to serve as endophenotypes for genetically predisposed psychiatric and neurological disorders. PMID:24453120

  14. Interaction of magnetic resonators studied by the magnetic field enhancement

    SciTech Connect

    Hou, Yumin, E-mail: ymhou@pku.edu.cn [State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871 (China)] [State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871 (China)

    2013-12-15

    It is the first time that the magnetic field enhancement (MFE) is used to study the interaction of magnetic resonators (MRs), which is more sensitive than previous parameters–shift and damping of resonance frequency. To avoid the coherence of lattice and the effect of Bloch wave, the interaction is simulated between two MRs with same primary phase when the distance is changed in the range of several resonance wavelengths, which is also compared with periodic structure. The calculated MFE oscillating and decaying with distance with the period equal to resonance wavelength directly shows the retardation effect. Simulation also shows that the interaction at normal incidence is sensitive to the phase correlation which is related with retardation effect and is ultra-long-distance interaction when the two MRs are strongly localized. When the distance is very short, the amplitude of magnetic resonance is oppressed by the strong interaction and thus the MFE can be much lower than that of single MR. This study provides the design rules of metamaterials for engineering resonant properties of MRs.

  15. Structural and functional magnetic resonance imaging correlates of motor network dysfunction in primary progressive multiple sclerosis.

    PubMed

    Ceccarelli, Antonia; Rocca, Maria A; Valsasina, Paola; Rodegher, Mariaemma; Falini, Andrea; Comi, Giancarlo; Filippi, Massimo

    2010-04-01

    We combined functional magnetic resonance imaging (fMRI) and diffusion tensor tractography to investigate the functional and structural substrates of motor network dysfunction in patients with primary progressive multiple sclerosis (PPMS). In 15 right-handed PPMS patients and 15 age-matched healthy controls, we acquired diffusion tensor magnetic resonance imaging and fMRI during the performance of a simple motor task. Tractography was used to calculate diffusion tensor-derived measures of the corpus callosum, the corticospinal tract, the optic radiation, the fronto-occipital fasciculus, and the inferior longitudinal fasciculus. Analyses of fMRI activations and functional connectivity were performed using statistical parametric mapping (cluster threshold of P = 0.001, and extent cluster threshold of 10 voxels for comparison of activations; P < 0.05, family-wise error corrected for functional connectivity). As compared with controls, PPMS patients had more significant activations of the left postcentral gyrus, left secondary sensorimotor area, left parahippocampal gyrus, left cerebellum, right primary sensorimotor cortex (SMC), right basal ganglia, right insula, right cingulum, and cuneus bilaterally. As compared with PPMS patients, controls had increased functional connectivity between the left primary SMC and the ipsilateral inferior frontal gyrus. Conversely, PPMS patients showed increased functional connectivity between the left primary SMC and the right cuneus. Moderate correlations were found between functional activations and damage to the tracts studied (r-values between 0.82 and 0.84; P < 0.001). These results suggest that, as compared with healthy controls, PPMS patients show increased activations and abnormal functional connectivity measures in several areas of the sensorimotor network. Such changes are correlated with the structural damage to the white matter fiber bundles connecting these regions. PMID:20345920

  16. 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.

  17. Magnetic Resonance Imaging and Magnetic Resonance Spectroscopy in Parkinson’s Disease

    Microsoft Academic Search

    W. R. Wayne Martin

    At present, conventional magnetic resonance imaging (MRI) shows no convincing structural changes in Parkinson’s disease (PD)\\u000a itself, but it may be useful in helping to distinguish PD from other neurodegenerative parkinsonian syndromes. Magnetic resonance\\u000a spectroscopy (MRS) also may provide useful information in distinguishing PD from disorders such as multiple system atrophy.\\u000a The general field of MRI and MRS is evolving

  18. 1H Magnetic resonance imaging and 31P magnetic resonance spectroscopy in experimental filariasis

    Microsoft Academic Search

    Amita Shukla-Dave; Nigar Fatma; Raja Roy; S. Srivastava; R. K. Chatterjee; V. Govindaraju; A. Kasi Viswanathan; P. Raghunathan

    1997-01-01

    1H Magnetic resonance imaging and 31P magnetic resonance spectroscopy (MRS) have been carried out in experimental rodent filariasis, i.e., Acanthocheilonema viteae infection in the rodent host, Mastomys coucha. The T2-weighted image of the infected host shows fine hyperintense thread like structures of adult filariid nests in the cervical region. 31P MRS of normal and infected hosts, localized over the same

  19. Nuclear magnetic resonance properties of lunar samples.

    NASA Technical Reports Server (NTRS)

    Kline, D.; Weeks, R. A.

    1972-01-01

    Nuclear magnetic resonance spectra of Na-23, Al-27, and P-31 in fines samples 10084,60 and 14163,168 and in crystalline rock samples 12021,55 and 14321,166, have been recorded over a range of frequencies up to 20 MHz. A shift in the field at which maximum absorption occurs for all of the spectra relative to the field at which maximum absorption occurs for terrestrial analogues is attributed to a sample-dependent magnetic field at the Na, Al, and P sites opposing the laboratory field. The magnitude of these fields internal to the samples is sample dependent and varies from 5 to 10 G. These fields do not correlate with the iron content of the samples. However, the presence of single-domain particles of iron distributed throughout the plagioclase fraction that contains the principal fraction of Na and Al is inferred from electron magnetic resonance spectra shapes.

  20. Non-Invasive Functional Mapping of the Brain Using Magnetoencephalography and Functional Magnetic Resonance Imaging.

    NASA Astrophysics Data System (ADS)

    Wang, Jihong

    Magnetoencephalography (MEG) and Functional Magnetic Resonance Imaging (FMRI) are two non-invasive techniques that can be used to study brain function. The first part of this dissertation discusses experimental factors that affect the accuracy of MEG source localization. These factors include measurement error, signal to noise ratio, number of measurement points and the local curvature of the head. A skull phantom and computer simulation were used to study the accuracy of MEG localization. It was found that the MEG dipole localization error was approximately 5-10 mm in the temporal region. This localization error was directly proportional to the digitization error. An empirical formula is given for the dependence of the MEG localization accuracy on the signal to noise ratio. The dependence of the MEG localization accuracy on the number of measurement points was also studied. Adequate coverage of extrema is necessary for accurate dipole localizations. The local curvature of the head does not affect localization accuracy as long as the center of the best fit sphere to this local surface is within 4 cm of the center of the best fit sphere to the whole head. The second part of the dissertation presents MEG and FMRI results of motor and auditory stimulation. It was found that the locations of auditory and motor activities as identified by MEG were in agreement with those identified by FMRI within 1-2 cm. The reasons for this discrepancy are discussed. The successful FMRI during auditory stimulation is reported. The fundamental aspects of the MEG inverse solution are discussed and a new spatiotemporal inverse solution algorithm is proposed.

  1. The Reporting of Observational Clinical Functional Magnetic Resonance Imaging Studies: A Systematic Review

    PubMed Central

    Guo, Qing; Parlar, Melissa; Truong, Wanda; Hall, Geoffrey; Thabane, Lehana; McKinnon, Margaret; Goeree, Ron; Pullenayegum, Eleanor

    2014-01-01

    Introduction Complete reporting assists readers in confirming the methodological rigor and validity of findings and allows replication. The reporting quality of observational functional magnetic resonance imaging (fMRI) studies involving clinical participants is unclear. Objectives We sought to determine the quality of reporting in observational fMRI studies involving clinical participants. Methods We searched OVID MEDLINE for fMRI studies in six leading journals between January 2010 and December 2011.Three independent reviewers abstracted data from articles using an 83-item checklist adapted from the guidelines proposed by Poldrack et al. (Neuroimage 2008; 40: 409–14). We calculated the percentage of articles reporting each item of the checklist and the percentage of reported items per article. Results A random sample of 100 eligible articles was included in the study. Thirty-one items were reported by fewer than 50% of the articles and 13 items were reported by fewer than 20% of the articles. The median percentage of reported items per article was 51% (ranging from 30% to 78%). Although most articles reported statistical methods for within-subject modeling (92%) and for between-subject group modeling (97%), none of the articles reported observed effect sizes for any negative finding (0%). Few articles reported justifications for fixed-effect inferences used for group modeling (3%) and temporal autocorrelations used to account for within-subject variances and correlations (18%). Other under-reported areas included whether and how the task design was optimized for efficiency (22%) and distributions of inter-trial intervals (23%). Conclusions This study indicates that substantial improvement in the reporting of observational clinical fMRI studies is required. Poldrack et al.'s guidelines provide a means of improving overall reporting quality. Nonetheless, these guidelines are lengthy and may be at odds with strict word limits for publication; creation of a shortened-version of Poldrack's checklist that contains the most relevant items may be useful in this regard. PMID:24755843

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

    Microsoft Academic Search

    Jaakko Koivuniemi; Reeta Luusalo; Pertti Hakonen

    1998-01-01

    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

  3. Genetically encoded reporters for hyperpolarized xenon magnetic resonance imaging

    E-print Network

    Schaffer, David V.

    Genetically encoded reporters for hyperpolarized xenon magnetic resonance imaging Mikhail G Pines5,6, David V. Schaffer2,7 and Vikram S. Bajaj5,6 * Magnetic resonance imaging (MRI) enables high , such that its magnetic resonance signal in a saturated aqueous solution at millimolar concentrations

  4. Magnetic Resonance Imaging Charles L. Epstein and Felix W. Wehrli

    E-print Network

    Magnetic Resonance Imaging Charles L. Epstein and Felix W. Wehrli June 3, 2005 1 Introduction Nuclear magnetic resonance (NMR) is a subtle quantum mechanical phenomenon that, through magnetic resonance imaging (MRI), has played a major role in the revolution in medical imaging over the last 30 years

  5. MBP 9662a: Nuclear Magnetic Resonance Prof. Blaine A. Chronik

    E-print Network

    Lennard, William N.

    MBP 9662a: Nuclear Magnetic Resonance Prof. Blaine A. Chronik Fall Semester, 2010 1 of 3 Medical Biophysics 9662a "Introductory Nuclear Magnetic Resonance" or "MRI 1: no gradients" Fall Semester, 2010 Course description: Nuclear Magnetic Resonance: The purpose of this course is to provide an understanding

  6. Nuclear Magnetic Resonance: Portable and integrated Lead: P. Poulichet.

    E-print Network

    Baudoin, Geneviève

    Nuclear Magnetic Resonance: Portable and integrated Lead: P. Poulichet. Permanent members: L. Rousseau, A. Fakri. Associated researchers: C. Delabie, A. Exertier. Portable Nuclear Magnetic Resonance of a prototype of a portable NMR (nuclear magnetic resonance) spectrometer prototype. As the volume of the sample

  7. Magnetic Resonance Imaging of Brain Function and Neurochemistry

    E-print Network

    Duong, Timothy Q.

    Magnetic Resonance Imaging of Brain Function and Neurochemistry KAMIL UGURBIL, DAE-SHIK KIM, TIM ANDERSEN, AND GREGOR ADRIANY Invited Paper In the past decade, magnetic resonance imaging (MRI) research approaches to map brain function. This capability, often referred to as functional magnetic resonance imaging

  8. A Scalable Framework For Segmenting Magnetic Resonance Images

    E-print Network

    Hall, Lawrence O.

    A Scalable Framework For Segmenting Magnetic Resonance Images Prodip Hore, Lawrence O. Hall, Dmitry, accurate and fully automatic method of segmenting magnetic resonance images of the human brain a framework for auto- matically segmenting magnetic resonance images of the human brain. The framework

  9. A Spectral-Scanning Magnetic Resonance Imaging (MRI) Integrated System

    E-print Network

    Hajimiri, Ali

    A Spectral-Scanning Magnetic Resonance Imaging (MRI) Integrated System Arjang Hassibi1,2 , Aydin of Texas at Austin, Austin, TX 78712, USA Abstract- An integrated spectral-scanning magnetic resonance customized magnetic resonance (MR) excitation signals, and also recovering the MR response using a coherent

  10. Laser-Assisted Magnetic Resonance: Principles and Applications

    E-print Network

    Suter, Dieter

    Laser-Assisted Magnetic Resonance: Principles and Applications D. Suter and J. Gutschank Universit radiation can be used in various magnetic resonance experiments. This chapter discusses a number of cases with the help of coherent optical radiation. 1 Introduction The interest in the field of magnetic resonance

  11. Classification of prostate magnetic resonance spectra using support vector machine

    E-print Network

    that nuclear magnetic resonance spectra are sensitive enough to distinguish normal and cancer. In this paperClassification of prostate magnetic resonance spectra using support vector machine S. Parfait a, we propose a classification technique of spectra from magnetic resonance spectroscopy. We studied au

  12. Material Classification of Magnetic Resonance Volume Data David H. Laidlaw

    E-print Network

    Material Classification of Magnetic Resonance Volume Data Thesis by David H. Laidlaw In Partial these traditional modeling methods. We use vector­valued magnetic resonance volume data in this thesis. The process and processing magnetic resonance data to meet the needs of the later steps. Our material classification

  13. Magnetic Earth Ionosphere Resonant Frequencies

    NASA Technical Reports Server (NTRS)

    Spaniol, Craig

    1994-01-01

    The Community College Division is pleased to report progress of NASA funded research at West Virginia State College. During this reporting period, the project research group has continued with activities to develop instrumentation capability designed to monitor resonant cavity frequencies in the atmospheric region between the Earth's surface and the ionosphere. In addition, the project's principal investigator, Dr. Craig Spaniol, and NASA technical officer, Dr. John Sutton, have written and published technical papers intended to expand the scientific and technical framework needed for project research. This research continues to provide an excellent example of government and education working together to provide significant research in the college environment. This cooperative effort has provided many students with technical project work which compliments their education.

  14. Musical training-induced functional reorganization of the adult brain: functional magnetic resonance imaging and transcranial magnetic stimulation study on amateur string players.

    PubMed

    Kim, Dong-Eog; Shin, Min-Jung; Lee, Kyoung-Min; Chu, Kon; Woo, Sung Ho; Kim, Young Ro; Song, Eun-Cheol; Lee, Jun-Won; Park, Seong-Ho; Roh, Jae-Kyu

    2004-12-01

    We used the combined technique of functional magnetic resonance imaging (fMRI) and transcranial magnetic stimulation (TMS) to observe changes that occur in adult brains after the practice of stringed musical instruments. We carried out fMRI on eight volunteers (aged 20-22 years): five novices and three individuals who had discontinued practice for more than 5 years. The motor paradigm contained a repetitive lift-abduction/fall-adduction movement of the left/right little finger, carried out with maximum efforts without pacing. The sensory paradigm was to stimulate the same little finger using a string. In parallel to the fMRI acquisition, TMS motor maps for the little finger were obtained using a frameless stereotactic neuronavigation system. After the baseline study, each participant began to learn a stringed instrument. Newly developed fMRI activations for the left little finger were observed 6 months after practice at multiple brain regions including inferior parietal lobule, premotor area (PMA), left precuneus, right anterior superior temporal gyrus, and posterior middle temporal gyrus. In contrast, new activations were rarely observed for the right little finger. The TMS study revealed new motor representation sites for the left little finger in the PMA or supplementary motor area (SMA). Unexpectedly, TMS motor maps for the right little finger were reduced significantly. Among new fMRI activations for sensory stimuli of the left little finger, the cluster of highest activation was located in the SMA. Collectively, these data provide insight into orchestrated reorganization of the sensorimotor and temporal association cortices contributing to the skillful fingering and musical processing after the practice of playing stringed instruments. PMID:15449354

  15. Longitudinal fMRI analysis: A review of methods

    PubMed Central

    Skup, Martha

    2010-01-01

    Functional magnetic resonance imaging (fMRI) investigations of a longitudinal nature, where participants are scanned repeatedly over time and imaging data are obtained at more than one time-point, are essential to understanding functional changes and development in healthy and pathological brains. The main objective of this paper is to provide a brief summary of common longitudinal analysis approaches, develop an overview of fMRI by introducing how such data manifest, and explore the statistical challenges that arise at the intersection of these two techniques. PMID:21691445

  16. Slow fluctuations in eye position and resting-state functional magnetic resonance imaging brain activity during visual fixation

    PubMed Central

    Fransson, Peter; Flodin, Pär; Seimyr, Gustaf Öqvist; Pansell, Tony

    2014-01-01

    The neuronal circuitry that supports voluntary changes in eye position in tasks that require attention-driven oculo-motor control is well known. However, less is known about the neuronal basis for eye control during visual fixation. This, together with the fact that visual fixation is one of the most commonly used baseline conditions in resting-state functional magnetic resonance imaging (fMRI) studies, prompted us to conduct a study in which we employed resting-state fMRI and concurrent recordings of eye gaze to investigate the relationship between spontaneous changes in eye position during passive visual fixation and intrinsic brain activity. As a control experiment, we recorded fMRI brain activity related to cued voluntary vertical and horizontal changes in eye position in a block-related task-evoked fMRI experiment. Our results for the voluntarily performed changes in eye position elicited brain activity in the bilateral occipitotemporal cortex, supplementary motor cortex and frontal eye fields. In contrast, we show that slow fluctuations in eye position during passive visual fixation are linked to intrinsic brain activity, foremost in midline cortical brain regions located in the posteromedial parietal cortex and the medial prefrontal cortex, brain regions that act as core cortical hubs in the brain's default mode network. Our results suggest that subconscious and sustained changes in behavior are tied to intrinsic brain activity on a moment-by-moment basis. PMID:25302817

  17. SEVEN TOPICS IN FUNCTIONAL MAGNETIC RESONANCE IMAGING

    PubMed Central

    BANDETTINI, PETER A.

    2010-01-01

    Functional MRI (fMRI) is a non-invasive brain imaging methodology that started in 1991 and allows human brain activation to be imaged at high resolution within only a few minutes. Because it has extremely high sensitivity, is relatively easy to implement, and can be performed on most standard clinical MRI scanners. It continues to grow at an explosive rate throughout the world. Over the years, at any given time, fMRI has been defined by only a handful of major topics that have been the focus of researchers using and developing the methodology. In this review, I attempt to take a snapshot of the field of fMRI as it is in mid-2009 by discussing the seven topics that I feel are most on the minds of fMRI researchers. The topics are, in no particular order or grouping: (1) Clinical impact, (2) Utilization of individual functional maps, (3) fMRI signal interpretation, (4) Pattern effect mapping and decoding, (5) Endogenous oscillations, (6) MRI technology, and (7) Alternative functional contrast mechanisms. Most of these topics are highly interdependent, each advancing as the others advance. While most fMRI involves applications towards clinical or neuroscience questions, all applications are fundamentally dependent on advances in basic methodology as well as advances in our understanding of the relationship between neuronal activity and fMRI signal changes. This review neglects almost completely an in-depth discussion of applications. Rather the discussions are on the methods and interpretation. PMID:19938211

  18. 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

  19. Magnetic resonance imaging of isolated single liposome by magnetic resonance force microscopy

    Microsoft Academic Search

    S. Tsuji; T. Masumizu; Y. Yoshinari

    2004-01-01

    Magnetic resonance imaging (MRI) is very useful spectroscopy to visualize a three-dimensional (3D) real structure inside the sample without physical destruction. The spatial resolution of the readily available MRI spectrometer is, however, limited by a few ten to hundreds of microns due to a technological boundary of generating larger magnetic field gradient and to the insensitivity inherent to the inductive

  20. GARANT-a general algorithm for resonance assignment of multidimensional nuclear magnetic resonance spectra

    Microsoft Academic Search

    Christian Bartels; Peter Güntert; Martin Billeter; Kurt Wüthrich

    1997-01-01

    A new program for automatic resonance assignment of nuclear magnetic resonance NMR spectra of proteins, GARANT General Algorithm for Resonance AssignmeNT, is introduced. Three principal elements used in this approach are: a. representation of resonance assignments as an optimal match of two graphs describing, respectively, peaks expected from combined knowledge of the primary structure and the magnetization transfer pathways in

  1. Resonant microwave cavity for 8.512 GHz optically detected electron spin resonance with simultaneous nuclear magnetic resonance

    E-print Network

    Hart, Gus

    with simultaneous nuclear magnetic resonance J. S. Colton1,a and L. R. Wienkes2 1 Department of Physics magnetic resonance ODMR experiments. The cylindrical quasi-TE011 mode cavity is designed to fit in a 1 in. magnet bore to allow the sample to be optically accessed and to have an adjustable resonant frequency

  2. Spin echo magnetic resonance imaging.

    PubMed

    Jung, Bernd André; Weigel, Matthias

    2013-04-01

    The spin echo sequence is a fundamental pulse sequence in MRI. Many of today's applications in routine clinical use are based on this elementary sequence. In this review article, the principles of the spin echo formation are demonstrated on which the generation of the fundamental image contrasts T1, T2, and proton density is based. The basic imaging parameters repetition time (TR) and echo time (TE) and their influence on the image contrast are explained. Important properties such as the behavior in multi-slice imaging or in the presence of flow are depicted and the basic differences with gradient echo imaging are illustrated. The characteristics of the spin echo sequence for different magnetic field strengths with respect to clinical applications are discussed. PMID:23526758

  3. MAGNETIC RESONANCE IN CHEMISTRY Magn. Reson. Chem. 2003; 41: S80S88

    E-print Network

    Wider, Gerhard

    MAGNETIC RESONANCE IN CHEMISTRY Magn. Reson. Chem. 2003; 41: S80­S88 Published online in Wiley of Nuclear Magnetic Resonance, volume 9, Advances in NMR, D. M. Grant and R. K. Harris (eds), Wiley magnetic fields typically used for studies of proteins and nucleic acids, chemical shift anisotropy (CSA

  4. Magnetic resonance of calcified tissues.

    PubMed

    Wehrli, Felix W

    2013-04-01

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

  5. Quantitative fMRI and oxidative neuroenergetics

    PubMed Central

    Hyder, Fahmeed; Rothman, Douglas L.

    2012-01-01

    The discovery of functional magnetic resonance imaging (fMRI) has greatly impacted neuroscience. The blood oxygenation level-dependent (BOLD) signal, using deoxyhemoglobin as an endogenous paramagnetic contrast agent, exposes regions of interest in task-based and resting-state paradigms. However the BOLD contrast is at best a partial measure of neuronal activity, because the functional maps obtained by differencing or correlations ignore the total neuronal activity in the baseline state. Here we describe how studies of brain energy metabolism at Yale, especially with 13C magnetic resonance spectroscopy and related techniques, contributed to development of quantitative functional brain imaging with fMRI by providing a reliable measurement of baseline energy. This narrative takes us on a journey, from molecules to mind, with illuminating insights about neuronal-glial activities in relation to energy demand of synaptic activity. These results, along with key contributions from laboratories worldwide, comprise the energetic basis for quantitative interpretation of fMRI data. PMID:22542993

  6. 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

  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 that a particle with angular momentum I and magnetic moment µ = I placed in a uniform mag- netic field B0

  8. Antiferromagnetic resonance excitation by terahertz magnetic field resonantly enhanced with split ring resonator

    SciTech Connect

    Mukai, Y. [Department of Physics, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502 (Japan); Hirori, H., E-mail: hirori@icems.kyoto-u.ac.jp [Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Sakyo-ku, Kyoto 606-8501 (Japan); CREST, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012 (Japan); Yamamoto, T. [Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510 (Japan); Kageyama, H. [Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Sakyo-ku, Kyoto 606-8501 (Japan); Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510 (Japan); Tanaka, K., E-mail: kochan@scphys.kyoto-u.ac.jp [Department of Physics, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502 (Japan); Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Sakyo-ku, Kyoto 606-8501 (Japan); CREST, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012 (Japan)

    2014-07-14

    Excitation of antiferromagnetic resonance (AFMR) in a HoFeO{sub 3} crystal combined with a split ring resonator (SRR) is studied using terahertz (THz) electromagnetic pulses. The magnetic field in the vicinity of the SRR is induced by the incident THz electric field component and excites spin oscillations that correspond to the AFMR, which are directly probed by the Faraday rotation of the polarization of a near-infrared probe pulse. The good agreement of the temperature-dependent magnetization dynamics with the calculation using the two-lattice Landau-Lifshitz-Gilbert equation confirms that the AFMR is excited by the THz magnetic field, which is enhanced at the SRR resonance frequency by a factor of 20 compared to the incident magnetic field.

  9. Antiferromagnetic resonance excitation by terahertz magnetic field resonantly enhanced with split ring resonator

    NASA Astrophysics Data System (ADS)

    Mukai, Y.; Hirori, H.; Yamamoto, T.; Kageyama, H.; Tanaka, K.

    2014-07-01

    Excitation of antiferromagnetic resonance (AFMR) in a HoFeO3 crystal combined with a split ring resonator (SRR) is studied using terahertz (THz) electromagnetic pulses. The magnetic field in the vicinity of the SRR is induced by the incident THz electric field component and excites spin oscillations that correspond to the AFMR, which are directly probed by the Faraday rotation of the polarization of a near-infrared probe pulse. The good agreement of the temperature-dependent magnetization dynamics with the calculation using the two-lattice Landau-Lifshitz-Gilbert equation confirms that the AFMR is excited by the THz magnetic field, which is enhanced at the SRR resonance frequency by a factor of 20 compared to the incident magnetic field.

  10. Foundations of Advanced Magnetic Resonance Imaging

    PubMed Central

    Bammer, Roland; Skare, Stefan; Newbould, Rexford; Liu, Chunlei; Thijs, Vincent; Ropele, Stefan; Clayton, David B.; Krueger, Gunnar; Moseley, Michael E.; Glover, Gary H.

    2005-01-01

    Summary: During the past decade, major breakthroughs in magnetic resonance imaging (MRI) quality were made by means of quantum leaps in scanner hardware and pulse sequences. Some advanced MRI techniques have truly revolutionized the detection of disease states and MRI can now—within a few minutes—acquire important quantitative information noninvasively from an individual in any plane or volume at comparatively high resolution. This article provides an overview of the most common advanced MRI methods including diffusion MRI, perfusion MRI, functional MRI, and the strengths and weaknesses of MRI at high magnetic field strengths. PMID:15897944

  11. Field-focusing nuclear magnetic resonance (FONAR)

    NASA Astrophysics Data System (ADS)

    Damadian, Raymond; Minkoff, Lawrence; Goldsmith, Michael; Koutcher, Jason A.

    1978-05-01

    A technique, field-focusing NMR (FONAR), is described for doing NMR scans in large samples. The method utilizes a shaped D.C. magnetic field that confines the NMR-signal-producing region of the sample to a small volume called the resonance aperture. The aperture contains the required values of the H o field to fully bracket the band of the r.f. pulse. The magnet system and r.f. pick-up coil that achieved the first human NMR scan is discussed.

  12. Journal of Magnetism and Magnetic Materials 286 (2005) 324328 Light-free magnetic resonance force microscopy for studies of

    E-print Network

    Journal of Magnetism and Magnetic Materials 286 (2005) 324­328 Light-free magnetic resonance force for Physical Sciences, College Park, MD, USA Available online 4 November 2004 Abstract Magnetic resonance force microscopy is a scanned probe technique capable of three-dimensional magnetic resonance imaging. Its

  13. 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.

  14. Combined Confocal and Magnetic Resonance Microscopy

    SciTech Connect

    Wind, Robert A.; Majors, Paul D.; Minard, Kevin R.; Ackerman, Eric J.; Daly, Don S.; Holtom, Gary R.; Thrall, Brian D.; Weber, Thomas J.

    2002-05-12

    Confocal and magnetic resonance microscopy are both used to study live cells in a minimally invasive way. Both techniques provide complementary information. Therefore, by examining cells simultaneously with both methodologies, more detailed information is obtained than is possible with each of the microscopes individually. In this paper two configurations of a combined confocal and magnetic resonance microscope described. In both cases the sample compartment is part of a temperature regulated perfusion system. The first configuration is capable of studying large single cells or three-dimensional cell agglomerates, whereas with the second configuration monolayers of mammalian cells can be investigated . Combined images are shown of Xenopus laevis frog oocytes, model JB6 tumor spheroids, and a single layer of Chinese hamster ovary cells. Finally, potential applications of the combined microscope are discussed.

  15. 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

  16. Resonant detection of axion mediated forces with Nuclear Magnetic Resonance

    E-print Network

    Asimina Arvanitaki; Andrew A. Geraci

    2014-03-05

    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.

  17. Resonantly Detecting Axion-Mediated Forces with Nuclear Magnetic Resonance

    NASA Astrophysics Data System (ADS)

    Arvanitaki, Asimina; Geraci, Andrew A.

    2014-10-01

    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 109 and 1012 GeV or axion masses between 10-6 and 10-3 eV, independent of the cosmic axion abundance.

  18. Cardiovascular Magnetic Resonance in Heart Failure

    Microsoft Academic Search

    Theodoros D. Karamitsos; Stefan Neubauer

    2011-01-01

    Imaging has a central role in the evaluation of patients with heart failure (HF). Cardiovascular magnetic resonance (CMR)\\u000a is rapidly evolving as a versatile imaging modality that often provides additional information to echocardiography in patients\\u000a with suspected or known HF. CMR is the only imaging modality that has the ability to assess, without exposure to ionizing\\u000a radiation, cardiac function, structure

  19. Magnetic Resonance Imaging Guidance for Tumor Ablation

    Microsoft Academic Search

    Koenraad J. Mortele; Stuart G. Silverman; Vito Cantisani; Kemal Tuncali; Sridhar Shankar; Eric vanSonnenberg

    Since the late 1980s, magnetic resonance imaging (MRI) has been added to ultrasound (US) and computed tomography (CT) as a\\u000a cross-sectional imaging tool that can be used to guide the interventional diagnosis and treatment of a variety of disorders.\\u000a Due to its superior soft tissue contrast, multiplanar capabilities, lack of ionizing radiation, and, most importantly, ability\\u000a to image tissue function

  20. Magnetic resonance imaging strategies for heart studies

    SciTech Connect

    Crooks, L.E.; Barker, B.; Chang, H.; Feinberg, D.; Hoenninger, J.C.; Watts, J.C.; Arakawa, M.; Kaufman, L.; Sheldon, P.E.; Botvinick, E.

    1984-11-01

    Given a suitable trigger signal, cardiac synchronized magnetic resonance (MR) imaging is simple to implement; however, single section techniques are not efficacious, especially when the heart rate sets the repetition interval. We demonstrate multi-section, double, and single-echo imaging, any of which rapidly covers the cardiac volume; 3-D modes capable of achieving very thin sections; and cycled multi-section imaging capable of efficaciously providing dynamic data on heart motion.

  1. Pharmaceutical applications of magnetic resonance imaging (MRI)

    Microsoft Academic Search

    J. Craig Richardson; Richard W. Bowtell; Karsten Mäder; Colin D. Melia

    2005-01-01

    Magnetic resonance imaging (MRI) is a powerful imaging modality that provides internal images of materials and living organisms on a microscopic and macroscopic scale. It is non-invasive and non-destructive, and one of very few techniques that can observe internal events inside undisturbed specimens in situ. It is versatile, as a wide range of NMR modalities can be accessed, and 2D

  2. Projective measurement in nuclear magnetic resonance

    E-print Network

    Jae-Seung Lee; A. K. Khitrin

    2006-05-02

    It is demonstrated that nuclear magnetic resonance experiments using pseudopure spin states can give possible outcomes of projective quantum measurement and probabilities of such outcomes. The physical system is a cluster of six dipolar-coupled nuclear spins of benzene in a liquid-crystalline matrix. For this system with the maximum total spin S=3, the results of measuring $S_X$ are presented for the cases when the state of the system is one of the eigenstates of $S_Z$.

  3. Magnetic Resonance Imaging of Acute Stroke

    Microsoft Academic Search

    Alison E. Baird; Steven Warach

    1998-01-01

    In the investigation of ischemic stroke, conventional structural magnetic resonance (MR) techniques (e.g., T1-weighted imaging, T2-weighted imaging, and proton density-weighted imaging) are valuable for the assessment of infarct extent and location beyond the first 12 to 24 hours after onset, and can be combined with MR angiography to noninvasively assess the intracranial and extracranial vasculature. However, during the critical first

  4. Adaptive Fuzzy Segmentation of Magnetic Resonance Images

    Microsoft Academic Search

    Dzung L. Pham; Jerry L. Prince

    1999-01-01

    An algorithm is presented for the fuzzy segmentation of two and three-dimensionalmultispectral magnetic resonance (MR) images that have been corrupted by intensity inhomogeneities,also known as shading artifacts. The algorithm is an extension of the two-dimensionaladaptive fuzzy C-means algorithm (2-D AFCM) presented in previous work by the authors. Thisalgorithm models the intensity inhomogeneities as a gain field that causes image intensities

  5. Nuclear magnetic resonance quantum information processing

    PubMed Central

    Serra, R. M.; Oliveira, I. S.

    2012-01-01

    For the past decade, nuclear magnetic resonance (NMR) has been established as a main experimental technique for testing quantum protocols in small systems. This Theme Issue presents recent advances and major challenges of NMR quantum information possessing (QIP), including contributions by researchers from 10 different countries. In this introduction, after a short comment on NMR-QIP basics, we briefly anticipate the contents of this issue. PMID:22946031

  6. 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.

  7. Magnetic resonance imaging in radiotherapy treatment planning

    Microsoft Academic Search

    Marinus Adriaan Moerland

    1996-01-01

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

  8. Travelling-wave nuclear magnetic resonance.

    PubMed

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

    2009-02-19

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

  9. Rhinopharyngoscopy, computed tomography and magnetic resonance imaging.

    PubMed

    Bonifazi, F; Bilò, M B; Antonicelli, L; Bonetti, M G

    1997-01-01

    Rhinitis is defined as nasal congestion, sneezing, itching and rhinorrhoea, recently classified as allergic, infective, structural or "other". The increasing employment of flexible rhynolaringoscopy may represent one of the most useful diagnostic tools in the complex differential diagnosis between allergic and nonallergic rhinitis. Furthermore, chronic allergic rhinitis, with secondary impairment of mucociliary clearance and the plethora of frequent anatomical variations, especially in the ostiomeatal complex, appear to predispose the patient to recurrent rhinosinusitis. In the last two decades, a better understanding of mucociliary clearance of nasal cavity and paranasal sinuses has shifted the attention from the maxillary sinuses to the area of the antherior ethmoid sinuses. Plain film radiographic examination, the historical standard, due to its inability to individualize ethmoid and sphenoid disease, is being rapidly supplanted by computed tomography and magnetic resonance imaging in the diagnosis of rhinosinusitis. In allergic and non-allergic rhinitis the diagnostic role of magnetic resonance imaging and computed tomography is still under debate. Computed tomography and magnetic resonance imaging are more efficient in demonstrating the bone wall, mucosal layer and sinus content than classical and computerized radiology; they have a higher diagnostic performance index in spite of a higher cost and, for computed tomography, a higher radiation dose. PMID:9188945

  10. Fluctuating magnetic field induced resonant activation

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    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.

  11. On the Dynamics of Magnetic Fluids in Magnetic Resonance Padraig J. Cantillon-Murphy

    E-print Network

    On the Dynamics of Magnetic Fluids in Magnetic Resonance Imaging by Padraig J. Cantillon in Magnetic Resonance Imaging by Padraig J. Cantillon-Murphy B.E., Electrical and Electronic Engineering to be used in magnetic resonance imaging (MRI) where they have found application as contrast agents

  12. Magnetic resonance imaging method based on magnetic susceptibility effects to estimate bubble size in alveolar products

    E-print Network

    Boyer, Edmond

    Magnetic resonance imaging method based on magnetic susceptibility effects to estimate bubble size-00454523,version1-8Feb2010 Author manuscript, published in "Magnetic Resonance Imaging 27, 4 (2009) p. 577 - p. 585" #12;Abstract18 19 20 21 22 23 24 25 26 27 28 29 30 Magnetic resonance imaging has proven its

  13. 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

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

    Microsoft Academic Search

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

    2005-01-01

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

  15. Activation of Cortical and Cerebellar Motor Areas during Executed and Imagined Hand Movements: An fMRI Study

    Microsoft Academic Search

    Martin Lotze; Pedro Montoya; Michael Erb; Ernst Hülsmann; Herta Flor; Uwe Klose; Niels Birbaumer; Wolfgang Grodd

    1999-01-01

    Brain activation during executed (EM) and imagined movements (IM) of the right and left hand was studied in 10 healthy right-handed subjects using functional magnetic resonance imagining (fMRI). Low electromyographic (EMG) activity of the musculi flexor digitorum superficialis and high vividness of the imagined movements were trained prior to image acquisition. Regional cerebral activation was measured by fMRI during EM

  16. 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

  17. Analysis of magnetic resonance imaging acoustic noise generated by a 4.7 T experimental system.

    PubMed

    Counter, S A; Olofsson, A; Borg, E; Bjelke, B; Häggström, A; Grahn, H F

    2000-09-01

    High intensity acoustic noise is an undesirable side-effect in magnetic resonance imaging (MRI) that can cause discomfort and hearing loss in patients and may be an impediment in functional MRI (fMRI) studies of the auditory system. Experimental MRI systems with high magnetic field strengths may generate acoustic noise of higher sound pressure levels (SPLs) than conventional 1.0 and 1.5 T clinical systems. We measured the SPL and spectral content of the acoustic noise generated by the Bruker Biospect 47/40 4.7 T experimental MRI system during scanning sequences commonly used in animal testing. Each sequence generated acoustic noise of high SPL, rapid pulse rates, amplitude-modulated pulse envelopes and multi-peaked spectra. The rapid acquisition with enhancement sequence with a 0.25 mm slice thickness generated SPLs of up to 129 dB peak SPL and 130 dB (A). Fourier analysis of the spectral content of the acoustic noise generated by each MRI sequence showed a wide band of acoustic energy with spectral peaks from 0.2-5 kHz. The intense MRI acoustic impulse noise generated by the 4.7 T system may cause masking of stimuli used in fMRI of the auditory cortex, reduce the hearing acuity of experimental animals and present a risk for unprotected human ears. PMID:11099151

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

    NASA Astrophysics Data System (ADS)

    Ibinson, James W.

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

  19. Electron Spin Magnetic Resonance Force Microscopy of Nitroxide Spin Labels

    NASA Astrophysics Data System (ADS)

    Moore, Eric W.; Lee, Sanggap; Hickman, Steven A.; Wright, Sarah J.; Marohn, John A.

    2009-03-01

    Nitroxide spin labels are widely used in electron spin resonance studies of biological and polymeric systems. Magnetic resonance force microscopy (MRFM) is a magnetic resonance technique that couples the high spatial resolution of a scanning probe microscope with the species selectivity of magnetic resonance. We report on our investigations of 4-amino TEMPO, a nitroxide spin label, by force-gradient MRFM. Our microscope operates at high vacuum in liquid helium, using a custom fabricated ultra-soft silicon cantilever in the magnet-on-cantilever geometry. An 18 GHz gap coupled microstripline resonator supplies the transverse field.

  20. 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.

  1. MAGNETIC RESONANCE ELECTRICAL IMPEDANCE TOMOGRAPHY (MR-EIT): A new technique for high resolution conductivity imaging

    E-print Network

    Eyüboðlu, Murat

    MAGNETIC RESONANCE ELECTRICAL IMPEDANCE TOMOGRAPHY (MR-EIT): A new technique for high resolution field measurements are performed by using magnetic resonance imaging techniques. The conductivity resonance imaging (MRI) techniques, if the conductor contains magnetic resonance active nuclei [2

  2. Gadolinium-Enhanced Magnetic Resonance Angiography for Pulmonary Embolism

    PubMed Central

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

    2011-01-01

    Background The accuracy of gadolinium-enhanced magnetic resonance pulmonary angiography and magnetic resonance venography for diagnosing pulmonary embolism has not been determined conclusively. Objective To investigate performance characteristics of magnetic resonance angiography, with or without magnetic resonance venography, for diagnosing pulmonary embolism. Design Prospective, multicenter study from 10 April 2006 to 30 September 2008. (ClinicalTrials.gov registration number: NCT00241826) Setting 7 hospitals and their emergency services. Patients 371 adults with diagnosed or excluded pulmonary embolism. Measurements Sensitivity, specificity, and likelihood ratios were measured by comparing independently read magnetic resonance imaging with the reference standard for diagnosing pulmonary embolism. Reference standard diagnosis or exclusion was made by using various tests, including computed tomographic angiography and venography, ventilation–perfusion lung scan, venous ultra-sonography, D-dimer assay, and clinical assessment. Results Magnetic resonance angiography, averaged across centers, was technically inadequate in 25% of patients (92 of 371). The proportion of technically inadequate images ranged from 11% to 52% at various centers. Including patients with technically inadequate images, magnetic resonance angiography identified 57% (59 of 104) with pulmonary embolism. Technically adequate magnetic resonance angiography had a sensitivity of 78% and a specificity of 99%. Technically adequate magnetic resonance angiography and venography had a sensitivity of 92% and a specificity of 96%, but 52% of patients (194 of 370) had technically inadequate results. Limitation A high proportion of patients with suspected embolism was not eligible or declined to participate. Conclusion Magnetic resonance pulmonary angiography should be considered only at centers that routinely perform it well and only for patients for whom standard tests are contraindicated. Magnetic resonance pulmonary angiography and magnetic resonance venography combined have a higher sensitivity than magnetic resonance pulmonary angiography alone in patients with technically adequate images, but it is more difficult to obtain technically adequate images with the 2 procedures. Primary Funding Source National Heart, Lung, and Blood Institute. PMID:20368649

  3. Least Squares Magnetic-Field Optimization for Portable Nuclear Magnetic Resonance Magnet Design

    Microsoft Academic Search

    Jeffrey L. Paulsen; John Franck; Vasiliki Demas; Louis-S. Bouchard

    2008-01-01

    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 in a cost function that minimizes the error

  4. Semiparametric detection of significant activation for brain fMRI

    E-print Network

    Zhang, Chunming

    2008-01-01

    Functional magnetic resonance imaging (fMRI) aims to locate activated regions in human brains when specific tasks are performed. The conventional tool for analyzing fMRI data applies some variant of the linear model, which is restrictive in modeling assumptions. To yield more accurate prediction of the time-course behavior of neuronal responses, the semiparametric inference for the underlying hemodynamic response function is developed to identify significantly activated voxels. Under mild regularity conditions, we demonstrate that a class of the proposed semiparametric test statistics, based on the local linear estimation technique, follow $\\chi^2$ distributions under null hypotheses for a number of useful hypotheses. Furthermore, the asymptotic power functions of the constructed tests are derived under the fixed and contiguous alternatives. Simulation evaluations and real fMRI data application suggest that the semiparametric inference procedure provides more efficient detection of activated brain areas than ...

  5. 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

  6. Southeastern Magnetic Resonance Conference October 11 -13, 2013

    E-print Network

    McQuade, D. Tyler

    42nd Southeastern Magnetic Resonance Conference October 11 - 13, 2013 Tallahassee, Florida The 42nd Southeastern Magnetic Resonance Conference will take place in the Florida capitol city of Tallahassee on the campus of T h e Florida State University. Additional information is located at http://semrc2013.magnet

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

    ERIC Educational Resources Information Center

    Seedhouse, Steven J.; Hoffmann, Markus M.

    2008-01-01

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

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

    PubMed

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

    2010-04-01

    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 increased neural activity according to whether the patient was experiencing hallucinations or veridical perception of faces, respectively. These findings may indicate key differences in how hallucinatory and veridical perceptions lead to the same phenomenological experience of seeing faces. PMID:19927262

  9. Quantitative Neuromorphometry Using Magnetic Resonance Histology

    PubMed Central

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

    2010-01-01

    Magnetic resonance imaging (MRI), now common in the clinical domain, has been adapted for use by the neuropathologist by increasing the spatial resolution over 100,000-times what is common in human clinical imaging. This increase in spatial resolution has been accomplished through a variety of technical advances—higher magnetic fields, more sensitive receivers, and clever encoding methods. Magnetic resonance histology (MRH), i.e. the application of MRI to study tissue specimens, now makes three-dimensional imaging of the fixed brain in the cranium routine. Active staining (perfusion fixation with a paramagnetic contrast agent) has allowed us to reduce the scan time by more than 8-times over earlier methods. The result is a three-dimensional isotropic image array that can be viewed along any direction without loss of spatial resolution. Homologous slices can be chosen interactively. Since the tissue is still fully hydrated in the cranium, tissue shrinkage and distortion are virtually eliminated. Volume measurements of neural structures can be made with a high degree of precision and accuracy. MRH will not replace more traditional methods, but it promises enormous value in choosing particular areas and times for more traditional sectioning and assessment. PMID:21119052

  10. A group model for stable multisubject ICA on fMRI datasets G. Varoquaux 1,3# , S. Sadaghiani 2,3 , P. Pinel 2,3 , A. Kleinschmidt 2,3 , J.B. Poline 3 , B. Thirion 1,3

    E-print Network

    A group model for stable multi­subject ICA on fMRI datasets G. Varoquaux 1,3# , S. Sadaghiani 2­sur­Yvette France + Funding from INRIA­INSERM collaboration. The fMRI set was acquired in the context­used data­driven method to analyze functional Magnetic Resonance Imaging (fMRI) data. To date, it has been

  11. 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

  12. Cardiac magnetic resonance in clinical cardiology

    PubMed Central

    Kumar, Andreas; Bagur, Rodrigo

    2015-01-01

    Over the last decades, cardiac magnetic resonance (CMR) has transformed from a research tool to a widely used diagnostic method in clinical cardiology. This method can now make useful, unique contributions to the work-up of patients with ischemic and non-ischemic heart disease. Advantages of CMR, compared to other imaging methods, include very high resolution imaging with a spatial resolution up to 0.5 mm × 0.5 mm in plane, a large array of different imaging sequences to provide in vivo tissue characterization, and radiation-free imaging. The present manuscript highlights the relevance of CMR in the current clinical practice and new perspectives in cardiology. PMID:25632313

  13. Magnetic resonance-guided prostate interventions.

    PubMed

    Haker, Steven J; Mulkern, Robert V; Roebuck, Joseph R; Barnes, Agnieska Szot; Dimaio, Simon; Hata, Nobuhiko; Tempany, Clare M C

    2005-10-01

    We review our experience using an open 0.5-T magnetic resonance (MR) interventional unit to guide procedures in the prostate. This system allows access to the patient and real-time MR imaging simultaneously and has made it possible to perform prostate biopsy and brachytherapy under MR guidance. We review MR imaging of the prostate and its use in targeted therapy, and describe our use of image processing methods such as image registration to further facilitate precise targeting. We describe current developments with a robot assist system being developed to aid radioactive seed placement. PMID:16924169

  14. Magnetic resonance imaging of primary breast lymphoma

    Microsoft Academic Search

    S. Rizzo; L. Preda; G. Villa; S. Brambilla; G. Pruneri; A. Alietti; E. Cassano; G. Martinelli; M. Bellomi

    2009-01-01

    Purpose  Primary lymphomas of the breast (PBNHL) are uncommon. Magnetic resonance imaging (MRI) features of these malignancies can\\u000a be relevant in establishing the extent of disease and planning the appropriate therapeutic strategy, usually represented by\\u000a chemo- and radiotherapy, rather than surgery. The purpose of this study was to assess MRI features of PBNHL.\\u000a \\u000a \\u000a \\u000a Materials and methods  MRI examinations performed on seven patients

  15. [Magnetic resonance imaging of atherosclerotic plaque].

    PubMed

    Ruehm, Stefan G

    2003-09-01

    Recent advances in terms of spatial and temporal resolution have enabled magnetic resonance imaging (MRI) to be used to display atherosclerotic plaque. MRI permits not only to detect atherosclerotic lesions but also enables determination of plaque volume and plaque characterization. It allows to display different plaque components such as lipid core, fibrous cap, calcium, and thrombus. To improve the spatial resolution, different invasive approaches based on intravascular coils have been evaluated. Novel contrast agent developments aim at the detection of inflammatory plaque activity in order to identify lesions with a high vascular risk (vulnerable plaque). PMID:14564414

  16. Approach to breast magnetic resonance imaging interpretation.

    PubMed

    Palestrant, Sarah; Comstock, Christopher E; Moy, Linda

    2014-05-01

    With the increasing use of breast magnetic resonance (MR) imaging comes the expectation that the breast radiologist is as fluent in its interpretation as in that of mammography and breast ultrasonography. Knowledge of who should be included for imaging and how to perform the imaging are as essential as interpreting the images. When reading the examination, the radiologist should approach the images from both a global and focused perspective, synthesizing findings into a report that includes a management plan. This article reviews a systematic and organized approach to breast MR imaging interpretation. PMID:24792657

  17. Magnetic resonance imaging of the elbow.

    PubMed

    Steinbach, L S; Fritz, R C; Tirman, P F; Uffman, M

    1997-11-01

    Magnetic resonance imaging (MRI) provides useful information regarding the elbow joint. Many abnormalities seen in the elbow are a result of trauma, often from sports such as baseball and tennis. Elbow problems are frequently related to the medial tension-lateral compression phenomenon where repeated valgus stress produces flexor-pronator strain, ulnar collateral ligament sprain, ulnar traction spurring, and ulnar neuropathy. The lateral compression causes osteochondritis dissecans of the capitellum and radial head, degenerative arthritis, and loose bodies. Other elbow abnormalities seen on MRI include radial collateral ligament injuries, biceps and triceps tendon injuries, other nerve entrapment syndromes, loose bodies, osseous and soft tissue trauma, arthritis, and masses, including bursae. PMID:9430831

  18. New magnetic resonance imaging methods in nephrology

    PubMed Central

    Zhang, Jeff L.; Morrell, Glen; Rusinek, Henry; Sigmund, Eric; Chandarana, Hersh; Lerman, Lilach O.; Prasad, Pottumarthi Vara; Niles, David; Artz, Nathan; Fain, Sean; Vivier, Pierre H.; Cheung, Alfred K.; Lee, Vivian S.

    2013-01-01

    Established as a method to study anatomic changes, such as renal tumors or atherosclerotic vascular disease, magnetic resonance imaging (MRI) to interrogate renal function has only recently begun to come of age. In this review, we briefly introduce some of the most important MRI techniques for renal functional imaging, and then review current findings on their use for diagnosis and monitoring of major kidney diseases. Specific applications include renovascular disease, diabetic nephropathy, renal transplants, renal masses, acute kidney injury and pediatric anomalies. With this review, we hope to encourage more collaboration between nephrologists and radiologists to accelerate the development and application of modern MRI tools in nephrology clinics. PMID:24067433

  19. Creating a magnetic resonance imaging ontology.

    PubMed

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

    2011-01-01

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

  20. Creating a magnetic resonance imaging ontology

    PubMed Central

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

    2011-01-01

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

  1. 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

  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. Neuroanatomical Distribution of Five Semantic Components of Verbs: Evidence from fMRI

    ERIC Educational Resources Information Center

    Kemmerer, David; Castillo, Javier Gonzalez; Talavage, Thomas; Patterson, Stephanie; Wiley, Cynthia

    2008-01-01

    The Simulation Framework, also known as the Embodied Cognition Framework, maintains that conceptual knowledge is grounded in sensorimotor systems. To test several predictions that this theory makes about the neural substrates of verb meanings, we used functional magnetic resonance imaging (fMRI) to scan subjects' brains while they made semantic…

  4. Brain Activation in Restrained and Unrestrained Eaters: An fMRI Study

    Microsoft Academic Search

    Maria Coletta; Steven Platek; Feroze B. Mohamed; J. Jason van Steenburgh; Deborah Green; Michael R. Lowe

    2009-01-01

    Restraint theory has been used to model the process that produces binge eating. However, there is no satisfactory explanation for the tendency of restrained eaters (REs) to engage in counterregulatory eating, an ostensible analogue of binge eating. Using functional magnetic resonance imaging (fMRI), the authors investigated brain activation of normal weight REs (N = 9) and unrestrained eaters (UREs; N

  5. An fMRI study of the human cortical motor system response to increasing functional demands

    Microsoft Academic Search

    Bruce E. Wexler; Robert K. Fulbright; Cheryl M. Lacadie; Pawel Skudlarski; Max B. Kelz; R. Todd Constable; John C. Gore

    1997-01-01

    Functional magnetic resonance imaging (fMRI) was used to study activation changes in the human primary motor-sensory areas (MAs), supplementary motor areas (SMAs), premotor areas (PMAs) and the superior and inferior parietal areas (SPAs, IPAs) during right hand finger movements as the rate, force and complexity of movement were varied. A preliminary reproducibility study of a single subject doing the same

  6. Automated quality assurance routines for fMRI data applied to a multicenter study

    Microsoft Academic Search

    Tony Stöcker; Frank Schneider; Martina Klein; Ute Habel; Thilo Kellermann; Karl Zilles; N. Jon Shah

    2005-01-01

    Standard procedures to achieve quality assessment (QA) of functional magnetic resonance imaging (fMRI) data are of great importance. A standardized and fully automated procedure for QA is presented that allows for classification of data quality and the detection of artifacts by inspecting temporal variations. The application of the procedure on phantom measurements was used to check scanner and stimulation hardware

  7. Using fMRI to Study Conceptual Change: Why and How?

    ERIC Educational Resources Information Center

    Masson, Steve; Potvin, Patrice; Riopel, Martin; Foisy, Lorie-Marlene Brault; Lafortune, Stephanie

    2012-01-01

    Although the use of brain imaging techniques, such as functional magnetic resonance imaging (fMRI) is increasingly common in educational research, only a few studies regarding science learning have so far taken advantage of this technology. This paper aims to facilitate the design and implementation of brain imaging studies relating to science…

  8. Dual-Tasking Alleviated Sleep Deprivation Disruption in Visuomotor Tracking: An fMRI Study

    ERIC Educational Resources Information Center

    Gazes, Yunglin; Rakitin, Brian C.; Steffener, Jason; Habeck, Christian; Butterfield, Brady; Basner, Robert C.; Ghez, Claude; Stern, Yaakov

    2012-01-01

    Effects of dual-responding on tracking performance after 49-h of sleep deprivation (SD) were evaluated behaviorally and with functional magnetic resonance imaging (fMRI). Continuous visuomotor tracking was performed simultaneously with an intermittent color-matching visual detection task in which a pair of color-matched stimuli constituted a…

  9. 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)

  10. Selective averaging of rapidly presented individual trials using fMRI

    Microsoft Academic Search

    Anders M. Dale; Randy L. Buckner

    1997-01-01

    A major limitation in conducting functional neuroimaging studies, particularly for cognitive experiments, has been the use of blocked task paradigms. Here we explored whether selective averaging techniques similar to those applied in event-related potential (ERP) experiments could be used to demonstrate functional magnetic resonance imaging (fMRI) responses to rapidly intermixed trials. In the first two experiments, we observed that for

  11. Brain Systems Mediating Aversive Conditioning: an Event-Related fMRI Study

    Microsoft Academic Search

    Christian Büchel; Jond Morris; Raymond J Dolan; Karl J Friston

    1998-01-01

    We have used event-related functional magnetic resonance imaging (fMRI) to characterize neural responses associated with emotional learning. Employing a classical conditioning paradigm in which faces were conditioned by pairing with an aversive tone (US), we compared responses evoked by conditioned (CS+) and nonconditioned (CS?) stimuli. Pairing 50% of the CS+ with the US enabled us to constrain our analysis to

  12. 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…

  13. Perceiving Age and Gender in Unfamiliar Faces: An fMRI Study on Face Categorization

    ERIC Educational Resources Information Center

    Wiese, Holger; Kloth, Nadine; Gullmar, Daniel; Reichenbach, Jurgen R.; Schweinberger, Stefan R.

    2012-01-01

    Efficient processing of unfamiliar faces typically involves their categorization (e.g., into old vs. young or male vs. female). However, age and gender categorization may pose different perceptual demands. In the present study, we employed functional magnetic resonance imaging (fMRI) to compare the activity evoked during age vs. gender…

  14. Neural Changes after Phonological Treatment for Anomia: An fMRI Study

    ERIC Educational Resources Information Center

    Rochon, Elizabeth; Leonard, Carol; Burianova, Hana; Laird, Laura; Soros, Peter; Graham, Simon; Grady, Cheryl

    2010-01-01

    Functional magnetic resonance imaging (fMRI) was used to investigate the neural processing characteristics associated with word retrieval abilities after a phonologically-based treatment for anomia in two stroke patients with aphasia. Neural activity associated with a phonological and a semantic task was compared before and after treatment with…

  15. Auditory Verb Perception Recruits Motor Systems in the Developing Brain: An fMRI Investigation

    ERIC Educational Resources Information Center

    James, Karin Harman; Maouene, Josita

    2009-01-01

    This study investigated neural activation patterns during verb processing in children, using fMRI (functional Magnetic Resonance Imaging). Preschool children (aged 4-6) passively listened to lists of verbs and adjectives while neural activation was measured. Findings indicated that verbs were processed differently than adjectives, as the verbs…

  16. 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

  17. Brain Correlates of Aesthetic Expertise: A Parametric fMRI Study

    ERIC Educational Resources Information Center

    Kirk, Ulrich; Skov, Martin; Christensen, Mark Schram; Nygaard, Niels

    2009-01-01

    Several studies have demonstrated that acquired expertise influences aesthetic judgments. In this paradigm we used functional magnetic resonance imaging (fMRI) to study aesthetic judgments of visually presented architectural stimuli and control-stimuli (faces) for a group of architects and a group of non-architects. This design allowed us to test…

  18. Toward brain correlates of natural behavior: fMRI during violent video games

    Microsoft Academic Search

    Klaus Mathiak; René Weber

    2006-01-01

    Modern video games represent highly advanced virtual reality simulations and often contain virtual violence. In a significant amount of young males, playing video games is a quotidian activity, making it an almost natural behavior. Recordings of brain activation with functional magnetic resonance imaging (fMRI) during gameplay may reflect neuronal correlates of real-life behavior. We recorded 13 experienced gamers (18 -26

  19. On the nature of the BOLD fMRI contrast mechanism

    Microsoft Academic Search

    Nikos K. Logothetis; Josef Pfeuffer

    2004-01-01

    Since its development about 15 years ago, functional magnetic resonance imaging (fMRI) has become the leading research tool for mapping brain activity. The technique works by detecting the levels of oxygen in the blood, point by point, throughout the brain. In other words, it relies on a surrogate signal, resulting from changes in oxygenation, blood volume and flow, and does

  20. Seeing Chinese Characters in Action: An fMRI Study of the Perception of Writing Sequences

    ERIC Educational Resources Information Center

    Yu, Hongbo; Gong, Lanyun; Qiu, Yinchen; Zhou, Xiaolin

    2011-01-01

    The Chinese character is composed of a finite set of strokes whose order in writing follows consensual principles and is learnt through school education. Using functional magnetic resonance imaging (fMRI), this study investigates the neural activity associated with the perception of writing sequences by asking participants to observe…

  1. 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

  2. Multi-Joint Arm Movements to Investigate Motor Control with fMRI

    Microsoft Academic Search

    R. Gassert; L. Dovat; G. Ganesh; E. Burdet; H. Imamizu; T. Milner; H. Bleuler

    2005-01-01

    Performing multi-joint arm movements in controllable dynamic environments during functional magnetic resonance imaging (fMRI) could provide important insights into the brain mechanisms involved in human motor control and related dysfunctions. In order to obtain useful data, these movements must be possible and comfortable for the subject within the narrow bore of the scanner and should not create any movement artifacts

  3. Three-Magnet Arrays for Unilateral Magnetic Resonance

    NASA Astrophysics Data System (ADS)

    Garcia Naranjo, Juan Carlos

    Unilateral Magnetic Resonance (UMR) has become, in different research areas, a powerful tool to interrogate samples of arbitrary size. The three-magnet array developed by the MRI Centre of the University of New Brunswick has features that make it a simple and robust approach for UMR. This thesis introduces a group of solutions to broaden the range of application of this design. Practical applications for non-destructive testing and reservoir core plug characterization are presented. We have shown that it is also possible to monitor the curing process of an epoxy/polyamidoamine system by employing a three-magnet array. A new version of the three-magnet array which features extended constant magnetic field gradients is also introduced. Constant gradients of more than 3 cm extent can be achieved in a very simple, compact and safe design. The application of the three-magnet array in combination with a solenoid as the RF probe for analysis of long core plugs has been presented. Core plugs of different diameter can be analyzed by simply changing the diameter of the RF probe employed for the measurement. Results of an initial survey of selective excitation in UMR are presented. The low SNR and inhomogeneities in the selective spot reduce the effectiveness of selective excitation for UMR.

  4. Science Drivers and Technical Challenges for Advanced Magnetic Resonance

    SciTech Connect

    Mueller, Karl T.; Pruski, Marek; Washton, Nancy M.; Lipton, Andrew S.

    2013-03-07

    This report recaps the "Science Drivers and Technical Challenges for Advanced Magnetic Resonance" workshop, held in late 2011. This exploratory workshop's goal was to discuss and address challenges for the next generation of magnetic resonance experimentation. During the workshop, participants from throughout the world outlined the science drivers and instrumentation demands for high-field dynamic nuclear polarization (DNP) and associated magnetic resonance techniques, discussed barriers to their advancement, and deliberated the path forward for significant and impactful advances in the field.

  5. Metabolite specific proton magnetic resonance imaging

    SciTech Connect

    Hurd, R.E.; Freeman, D.M.

    1989-06-01

    An imaging method is described that makes use of proton double quantum nuclear magnetic resonance (NMR) to construct images based on selected metabolites such as lactic acid. The optimization of the method is illustrated in vitro, followed by in vivo determination of lactic acid distribution in a solid tumor model. Water suppression and editing of lipid signals are such that two-dimensional spectra of lactic acid may be obtained from a radiation-induced fibrosarcoma (RIF-1) tumor in under 1 min and lactic acid images from the same tumor in under 1 hr at 2.0 T. This technique provides a fast and reproducible method at moderate magnetic field strength for mapping biologically relevant metabolites.

  6. In vivo nuclear magnetic resonance imaging

    NASA Technical Reports Server (NTRS)

    Leblanc, A.

    1986-01-01

    During the past year the Woodlands Baylor Magnetic Resonance Imaging (MRI) facility became fully operational. A detailed description of this facility is given. One significant instrument addition this year was the 100 MHz, 40cm bore superconducting imaging spectrometer. This instrument gives researchers the capability to acquire high energy phosphate spectra. This will be used to investigate ATP, phosphocreatinine and inorganic phosphate changes in normal and atrophied muscle before, during and after exercise. An exercise device for use within the bore of the imaging magnet is under design/construction. The results of a study of T sub 1 and T sub 2 changes in atrophied muscle in animals and human subjects are given. The imaging and analysis of the lower leg of 15 research subjects before and after 5 weeks of complete bedrest was completed. A compilation of these results are attached.

  7. Nuclear magnetic resonance imaging of liver hemangiomas

    SciTech Connect

    Sigal, R.; Lanir, A.; Atlan, H.; Naschitz, J.E.; Simon, J.S.; Enat, R.; Front, D.; Israel, O.; Chisin, R.; Krausz, Y.

    1985-10-01

    Nine patients with cavernous hemangioma of the liver were examined by nuclear magnetic resonance imaging (MRI) with a 0.5 T superconductive magnet. Spin-echo technique was used with varying time to echo (TE) and repetition times (TR). Results were compared with /sup 99m/Tc red blood cell (RBC) scintigraphy, computed tomography (CT), echography, and arteriography. Four illustrated cases are reported. It was possible to establish a pattern for MRI characteristics of cavernous hemangiomas; rounded or smooth lobulated shape, marked increase in T1 and T2 values as compared with normal liver values. It is concluded that, although more experience is necessary to compare the specificity with that of ultrasound and CT, MRI proved to be very sensitive for the diagnosis of liver hemangioma, especially in the case of small ones which may be missed by /sup 99m/Tc-labeled RBC scintigraphy.

  8. Response inhibition and impulsivity: an fMRI study

    Microsoft Academic Search

    N. R. Horn; M. Dolan; R. Elliott; J. F. W. Deakin; P. W. R. Woodruff

    2003-01-01

    Aggressive, suicidal and violent behaviour have been associated with impulsive personality and difficulty in inhibiting responses. We used functional magnetic resonance imaging (fMRI) of the whole brain to examine the neural correlates of response inhibition in 19 normal subjects as they performed a Go\\/NoGo task. Subjects completed Eysenck’s Impulsivity Scale, Barratt’s Impulsivity Scale (BIS) and behavioural impulsivity tasks. Associations between

  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. Optimal experimental design for event-related fMRI

    Microsoft Academic Search

    Anders M. Dale

    1999-01-01

    An important challenge in the design and analysis of event-related or single-trial functional magnetic resonance imaging (fMRI) experiments is to optimize statistical efficiency, i.e., the accuracy with which the event-related hemodynamic response to different stimuli can be estimated for a given amount of imaging time. Several studies have suggested that using a fixed inter-stimulus-interval (ISI) of at least 15 sec

  11. Model-independent method for fMRI analysis

    Microsoft Academic Search

    Hamid Soltanian-Zadeh; Donald J. Peck; David O. Hearshen; Renee R. Lajiness-O'Neill

    2004-01-01

    This paper presents a fast method for delineation of activated areas of the brain from functional magnetic resonance imaging (fMRI) time series data. The steps of the work accomplished are as follows. 1) It is shown that the detection performance evaluated by the area under the receiver operating characteristic curve is directly related to the signal-to-noise ratio (SNR) of the

  12. THE USE OF MAGNETIC RESONANCE SPECTROSCOPY AND MAGNETIC RESONANCE IMAGING IN ALCOHOL RESEARCH

    Microsoft Academic Search

    Bonnie J. Nagel; Christopher D. Kroenke

    2008-01-01

    he recent emergence of magnetic resonance (MR)­ based neuroimaging techniques has dramatically improved researchers' ability to understand the neuro­ pathology of alcoholism. These techniques range from those that directly monitor the metabolism and the biochemical and physiological effects (i.e., the pharmacodynamics) of alcohol within the brain to techniques that examine the impact of heavy alcohol use on brain structure and

  13. Methods for chemical exchange saturation transfer magnetic resonance imaging

    E-print Network

    Scheidegger, Rachel Nora

    2013-01-01

    Chemical exchange saturation transfer (CEST) is a relatively new magnetic resonance imaging (MRI) acquisition technique that generates contrast dependent on tissue microenvironment, such as protein concentration and ...

  14. 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

  15. Functional Magnetic Resonance Imaging Findings in Meares-Irlen Syndrome: A Pilot Sudy

    PubMed Central

    Kim, Ji Hyun; Seo, Hye-Jin; Ha, Suk-Gyu

    2015-01-01

    Purpose To investigate patterns of functional magnetic resonance imaging (fMRI) activation during sentence reading before and after wearing color-tinted lenses. Methods A total of 15 Meares-Irlen syndrome patients with a mean age of 23.4 years (range, 13 to 42 years) with no history of neurological or psychiatric disorders were scanned using a 3T MR scanner (Siemens, Tim-Trio, Germany). Each patient underwent two sessions of fMRI imaging (before and after MISViS color-tinted lens application). The fMRI paradigm included a block design of 20 seconds of rest (cross), 20 seconds of activation (sentence reading), and ten blocks (a total of 200 echo-planar image volumes) repeated for each session. Data preprocessing and analyses were performed using the SPM8 software package. Results The reading speed of patients improved more than 20% while wearing the selected lenses. When compared to the before-lens session, the after-lens session identified significant regions of activation in the left middle and superior temporal gyri (paired t-test; maximal z score, 5.38; Montreal Neurological Institute coordinate, -60 / -39 / 0; threshold at p < 0.05; corrected for multiple comparisons using family-wise error). No region of activation at the same threshold was found in the before-lens session as compared to the after-lens session. Conclusions In the current study, we confirmed activation in the left middle and superior temporal gyri during sentence reading after wearing color-tinted lenses. These results could explain the effectiveness of color-tinted lenses in patients with Meares-Irlen syndrome. PMID:25829829

  16. Volumetric segmentation of magnetic resonance images

    NASA Astrophysics Data System (ADS)

    Lee, James D.; Rodriguez, Jeffrey J.

    1994-09-01

    Current computer graphics techniques can generate 3-D views of the human anatomy from magnetic resonance images. These techniques require that the images first be segmented into the various tissue types. However, there has been no fully automated system that can perform this task on a single set of high-resolution 3-D magnetic resonance images. We present a fully automated segmentation algorithm based on the 3-D difference of Gaussians (DOG) filter. A novel method for the classification of regions found by the DOG filter, as well as a correction procedure that detects errors from the DOG filter, is presented. Regions are classified based on the mean gray level of the voxels within closed contours. In previous work, the user had to manually split falsely merged regions. Our automated correction algorithm detects such errors and splits the merged regions. Spatial information is also incorporated to help discriminate between tissues. Encouraging results were obtained with an average of less than five percent error in each image. Integral shading is used to obtain a 3-D rendering of the data set.

  17. 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

  18. Nuclear magnetic resonance in magnets with a helicoidal magnetic structure in an external magnetic field

    NASA Astrophysics Data System (ADS)

    Tankeyev, A. P.; Borich, M. A.; Smagin, V. V.

    2014-11-01

    In this review, the static and dynamic properties of a magnet with a helicoidal magnetic structure placed in an external magnetic field are discussed. The results of the investigation of its ground state and spectra, as well as the amplitudes of the spin excitations are presented. The temperature and field dependences of the basic thermodynamic characteristics (heat capacity, magnetization, and magnetic susceptibility) have been calculated in the spin-wave approximation. The results of calculating the local and integral dynamic magnetic susceptibility are given. This set of data represents a methodical basis for constructing a consistent (in the framework of unified approximations) picture of the NMR absorption in the magnet under consideration. Both local NMR characteristics (resonance frequency, line broadening, enhancement coefficient) and integral characteristics (resultant shape of the absorption line with its specific features) have been calculated. The effective Hamiltonian of the Suhl-Nakamura interaction of nuclear spins through spin waves has been constructed. The second moment and the local broadening of the line of the NMR absorption caused by this interaction have been calculated. The role of the basic local inhomogeneities in the formation of the integral line of the NMR absorption has been analyzed. The opportunities for the experimental NMR investigations in magnets with a chiral spin structure are discussed.

  19. 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 ...

  20. Striatal contributions to working memory: a functional magnetic resonance imaging study in humans.

    PubMed

    Lewis, Simon J G; Dove, Anja; Robbins, Trevor W; Barker, Roger A; Owen, Adrian M

    2004-02-01

    Although the role of the frontal cortex in executive performance has been widely accepted, issues regarding the contribution of subcortical structures to these functions remain unresolved. In this study, the neural circuitry underlying selective subcomponents of working memory was investigated using event-related functional magnetic resonance imaging (fMRI). Ten healthy volunteers performed a verbal memory task, which allowed different aspects of working memory function such as maintenance, retrieval and manipulation to be tested within the same general paradigm. During performance of this task as a whole, fMRI revealed increases in signal intensity throughout the frontostriatal network. However, when signal intensity during the manipulation of information within working memory was compared to that during periods requiring only simple maintenance and retrieval, significant changes were observed only in the caudate nuclei, bilaterally. These results suggest an essential and specific role for the caudate nucleus in executive function, which may underlie the cognitive disturbances observed in frontostriatal neurodegenerative disorders such as Parkinson's disease. PMID:14984425

  1. 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

  2. Antinociceptive activity of crotoxin in the central nervous system: a functional Magnetic Resonance Imaging study.

    PubMed

    Wolz-Richter, S; Esser, K-H; Hess, A

    2013-11-01

    Crotoxin, the main neurotoxic component of the venom of South American rattlesnake (Crotalus durissus terrificus), is reported to have potent antinociceptive activity. Several authors have shown mainly in behavioral pain models that crotoxin induces antinociceptive effects, supposed to be mediated by actions on the central nervous system. The antinociceptive effects of crotoxin (45 ?g/kg ip) in rats were verified in this study by increased response latencies in a Hargreaves test and tail flick test. In addition, it was demonstrated that crotoxin does not lead to motor impairments during a rotarod test and open field test. The main objective, carried out by blood oxygen level dependent functional Magnetic Resonance Imaging (BOLD fMRI) in anesthetized rats, was to determine which specific brain structures are involved in these antinociceptive effects. Moreover, potential antihyperalgesic effects were investigated by inducing a local hyperalgesia on the left hind paw. Therefore, antinociceptive effects (right paw) and antihyperalgesic effects (left paw) of crotoxin were able to be differentiated. As a result, crotoxin exhibited dominant antihyperalgesic but also antinociceptive effects during pain stimulation. Reductions of BOLD signal already occurred in brain input structures but were most prominent in primary and secondary somatosensory cortices. In conclusion, BOLD fMRI in anesthetized rats proved to be a helpful tool in toxinology, particularly in unraveled mechanisms of modulating nociception in the central nervous system by (potential) analgesics like crotoxin. PMID:23916599

  3. Auditory orienting and inhibition of return in schizophrenia: A functional magnetic resonance imaging study

    PubMed Central

    Abbott, Christopher C.; Merideth, Flannery; Ruhl, David; Yang, Zhen; Clark, Vincent P.; Calhoun, Vince D.; Hanlon, Faith M.; Mayer, Andrew R.

    2011-01-01

    Patients with schizophrenia (SP) exhibit deficits in both attentional reorienting and inhibition of return (IOR) during visual tasks. However, it is currently unknown whether these deficits are supramodal in nature and how these deficits relate to other domains of cognitive dysfunction. In addition, the neuronal correlates of this pathological orienting response have not been investigated in either the visual or auditory modality. Therefore, thirty SP and 30 healthy controls (HC) were evaluated with an extensive clinical protocol and functional magnetic resonance imaging (fMRI) during an auditory cuing paradigm. SP exhibited both increased costs and delayed IOR during auditory orienting, suggesting a prolonged interval for attentional disengagement from cued locations. Moreover, a delay in the development of IOR was associated with cognitive deficits on formal neuropsychological testing in the domains of attention/inhibition and working memory. Event-related fMRI showed the characteristic activation of a frontoparietal network (invalid trials > valid trials), but there were no differences in functional activation between patients and HC during either attentional reorienting or IOR. Current results suggest that orienting deficits are supramodal in nature in SP, and are related to higher-order cognitive deficits that directly interfere with day-to-day functioning. PMID:22230646

  4. Reciprocity and gyrotropism in magnetic resonance transduction

    NASA Astrophysics Data System (ADS)

    Tropp, James

    2006-12-01

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

  5. Event-related single-shot volumetric functional magnetic resonance inverse imaging of visual processing.

    PubMed

    Lin, Fa-Hsuan; Witzel, Thomas; Mandeville, Joseph B; Polimeni, Jonathan R; Zeffiro, Thomas A; Greve, Douglas N; Wiggins, Graham; Wald, Lawrence L; Belliveau, John W

    2008-08-01

    Developments in multi-channel radio-frequency (RF) coil array technology have enabled functional magnetic resonance imaging (fMRI) with higher degrees of spatial and temporal resolution. While modest improvement in temporal acceleration has been achieved by increasing the number of RF coils, the maximum attainable acceleration in parallel MRI acquisition is intrinsically limited only by the amount of independent spatial information in the combined array channels. Since the geometric configuration of a large-n MRI head coil array is similar to that used in EEG electrode or MEG SQUID sensor arrays, the source localization algorithms used in MEG or EEG source imaging can be extended to also process MRI coil array data, resulting in greatly improved temporal resolution by minimizing k-space traversal during signal acquisition. Using a novel approach, we acquire multi-channel MRI head coil array data and then apply inverse reconstruction methods to obtain volumetric fMRI estimates of blood oxygenation level dependent (BOLD) contrast at unprecedented whole-brain acquisition rates of 100 ms. We call this combination of techniques magnetic resonance Inverse Imaging (InI), a method that provides estimates of dynamic spatially-resolved signal change that can be used to construct statistical maps of task-related brain activity. We demonstrate the sensitivity and inter-subject reliability of volumetric InI using an event-related design to probe the hemodynamic signal modulations in primary visual cortex. Robust results from both single subject and group analyses demonstrate the sensitivity and feasibility of using volumetric InI in high temporal resolution investigations of human brain function. PMID:18538587

  6. Semiblind spatial ICA of fMRI using spatial constraints.

    PubMed

    Lin, Qiu-Hua; Liu, Jingyu; Zheng, Yong-Rui; Liang, Hualou; Calhoun, Vince D

    2010-07-01

    Independent component analysis (ICA) utilizing prior information, also called semiblind ICA, has demonstrated considerable promise in the analysis of functional magnetic resonance imaging (fMRI). So far, temporal information about fMRI has been used in temporal ICA or spatial ICA as additional constraints to improve estimation of task-related components. Considering that prior information about spatial patterns is also available, a semiblind spatial ICA algorithm utilizing the spatial information was proposed within the framework of constrained ICA with fixed-point learning. The proposed approach was first tested with synthetic fMRI-like data, and then was applied to real fMRI data from 11 subjects performing a visuomotor task. Three components of interest including two task-related components and the "default mode" component were automatically extracted, and atlas-defined masks were used as the spatial constraints. The default mode network, a set of regions that appear correlated in particular in the absence of tasks or external stimuli and is of increasing interest in fMRI studies, was found to be greatly improved when incorporating spatial prior information. Results from simulation and real fMRI data demonstrate that the proposed algorithm can improve ICA performance compared to a different semiblind ICA algorithm and a standard blind ICA algorithm. PMID:20017117

  7. Towards a virtual laboratory for FMRI data management and analysis.

    PubMed

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

    2006-01-01

    Functional Magnetic Resonance Imaging (fMRI) is a popular tool used in neuroscience research to study brain activation due to motor or cognitive stimulation. In fMRI studies, large amounts of data are acquired, processed, compared, annotated, shared by many users and archived for future reference. As such, fMRI studies have characteristics of applications that can benefit from grid computation approaches, in which users associated with virtual organizations can share high performance and large capacity computational resources. In the Virtual Laboratory for e-Science (VL-e) Project, initial steps have been taken to build a grid-enabled infrastructure to facilitate data management and analysis for fMRI. This article presents our current efforts for the construction of this infrastructure. We start with a brief overview of fMRI, and proceed with an analysis of the existing problems from a data management perspective. A description of the proposed infrastructure is presented, and the current status of the implementation is described with a few preliminary conclusions. PMID:16823122

  8. Directly Mapping Magnetic Field Effects of Neuronal Activity by Magnetic Resonance

    E-print Network

    Gabrieli, John

    Directly Mapping Magnetic Field Effects of Neuronal Activity by Magnetic Resonance Imaging Jinhu Center at San Antonio, San Antonio, Texas Abstract: Magnetic resonance imaging (MRI) of brain functional functional activity by directly detecting magnetic fields induced by neuronal firing. Using a well

  9. Magnetic Resonance Imaging Methods in Soil Science

    NASA Astrophysics Data System (ADS)

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

    2009-04-01

    Magnetic Resonance Imaging (MRI) is a powerful technique to study water content, dynamics and transport in natural porous media. However, MRI systems and protocols have been developed mainly for medical purposes, i.e. for media with comparably high water contents and long relaxation times. In contrast, natural porous media like soils and rocks are characterized by much lower water contents, typically 0 < theta < 0.4, and much faster T1 and T2 relaxation times. So, the usage of standard medical scanners and protocols is of limited benefit. Three strategies can be applied for the monitoring of water contents and dynamics in natural porous media: i) Dedicated high-field scanners (with vertical bore) allowing stronger gradients and faster switching so that shorter echo times can be realized. ii) Special measurement sequences using ultrashort rf- and gradient-pulses like single point imaging derivates (SPI, SPRITE)(1) and multi-echo methods, which monitor series of echoes and allow for extrapolation to zero time(2). Hence, the loss of signal during the first echo period may be compensated to determine the initial magnetization (= water content) as well as relaxation time maps simultaneously. iii) Finally low field( < 1T) scanners also provide longer echo times and hence detect larger fractions of water, since the T2 relaxation time of water in most porous media increases with decreasing magnetic field strength(3). In the presentation examples for all three strategies will be given. References 1) Pohlmeier et al. Vadose Zone J. 7, 1010-1017 (2008) 2) Edzes et al., Magn. Res. Imag. 16, 185-196 (1998) 3) Raich H, and Blümler P, Concepts in Magn. Reson. B 23B, 16-25 (2004) 4) Pohlmeier et al. Magn. Res. Imag. doi:10.1016/j.mri.2008.06.007 (2008)

  10. 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

  11. Ultrahigh-Resolution Magnetic Resonance in Inhomogeneous Magnetic Fields: Two-Dimensional Long-Lived-Coherence Correlation Spectroscopy

    E-print Network

    Ultrahigh-Resolution Magnetic Resonance in Inhomogeneous Magnetic Fields: Two-Dimensional Long resolution in Nuclear Magnetic Resonance (NMR) and Magnetic Resonance Imaging (MRI) has enabled the study.56.Fk, 82.56.Pp, 82.56.Jn Nuclear magnetic resonance (NMR) is often regarded as one of the most

  12. Functional magnetic resonance imaging during emotion recognition in social anxiety disorder: an activation likelihood meta-analysis

    PubMed Central

    Hattingh, Coenraad J.; Ipser, J.; Tromp, S. A.; Syal, S.; Lochner, C.; Brooks, S. J.; Stein, D. J.

    2012-01-01

    Background: Social anxiety disorder (SAD) is characterized by abnormal fear and anxiety in social situations. Functional magnetic resonance imaging (fMRI) is a brain imaging technique that can be used to demonstrate neural activation to emotionally salient stimuli. However, no attempt has yet been made to statistically collate fMRI studies of brain activation, using the activation likelihood-estimate (ALE) technique, in response to emotion recognition tasks in individuals with SAD. Methods: A systematic search of fMRI studies of neural responses to socially emotive cues in SAD was undertaken. ALE meta-analysis, a voxel-based meta-analytic technique, was used to estimate the most significant activations during emotional recognition. Results: Seven studies were eligible for inclusion in the meta-analysis, constituting a total of 91 subjects with SAD, and 93 healthy controls. The most significant areas of activation during emotional vs. neutral stimuli in individuals with SAD compared to controls were: bilateral amygdala, left medial temporal lobe encompassing the entorhinal cortex, left medial aspect of the inferior temporal lobe encompassing perirhinal cortex and parahippocampus, right anterior cingulate, right globus pallidus, and distal tip of right postcentral gyrus. Conclusion: The results are consistent with neuroanatomic models of the role of the amygdala in fear conditioning, and the importance of the limbic circuitry in mediating anxiety symptoms. PMID:23335892

  13. Increasing the reliability of data analysis of functional magnetic resonance imaging by applying a new blockwise permutation method

    PubMed Central

    Adolf, Daniela; Weston, Snezhana; Baecke, Sebastian; Luchtmann, Michael; Bernarding, Johannes; Kropf, Siegfried

    2014-01-01

    A recent paper by Eklund et al. (2012) showed that up to 70% false positive results may occur when analyzing functional magnetic resonance imaging (fMRI) data using the statistical parametric mapping (SPM) software, which may mainly be caused by insufficient compensation for the temporal correlation between successive scans. Here, we show that a blockwise permutation method can be an effective alternative to the standard correction method for the correlated residuals in the general linear model, assuming an AR(1)-model as used in SPM for analyzing fMRI data. The blockwise permutation approach including a random shift developed by our group (Adolf et al., 2011) accounts for the temporal correlation structure of the data without having to provide a specific definition of the underlying autocorrelation model. 1465 publicly accessible resting-state data sets were re-analyzed, and the results were compared with those of Eklund et al. (2012). It was found that with the new permutation method the nominal familywise error rate for the detection of activated voxels could be maintained approximately under even the most critical conditions in which Eklund et al. found the largest deviations from the nominal error level. Thus, the method presented here can serve as a tool to ameliorate the quality and reliability of fMRI data analyses. PMID:25165444

  14. 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.

  15. Sensitivity of Optically Enhanced Magnetic Resonance While magnetic resonance is one of the less sensitive spectroscopic techniques, there are a number

    E-print Network

    Suter, Dieter

    Sensitivity of Optically Enhanced Magnetic Resonance While magnetic resonance is one of the less electronic or nuclear spins. Compared to conventional magnetic resonance, the sensitivity can be increased. Polarization Figure 1: Spin polarization The magnetic resonance signal is generally proportional to the degree

  16. RESEARCH Open Access H low field nuclear magnetic resonance

    E-print Network

    Stanford University

    produced by a chemical reaction named transesterification (TE), where a lipid is reacted with an alcoholRESEARCH Open Access Novel 1 H low field nuclear magnetic resonance applications for the field Field Nuclear Magnetic Resonance (LF-NMR) applications, which offer great potential to the field

  17. Hybrid Magnetic Resonance Angiography and Quantitative Volume Flow Measurement

    Microsoft Academic Search

    Ping Hou

    1993-01-01

    Volume blood flow rate correlates directly with oxygen delivery for aerobic metabolism and is thus clinically more significant than velocity in the diagnosis of vascular diseases. In this dissertation, an magnetic resonance imaging (MRI) technique has been developed to directly measure flow rate. A two echo hybrid magnetic resonance angiography (MRA) pulse sequence has been designed and implemented to obtain

  18. 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

  19. Improved Preparation of Chick Embryonic Samples for Magnetic Resonance Microscopy

    E-print Network

    Improved Preparation of Chick Embryonic Samples for Magnetic Resonance Microscopy Xiaowei Zhang,1 T voxels for three stages of chick embryos (day 4, day 5.5, and day 9), and com- pared to histological words: magnetic resonance microscopy; heart develop- ment; embryo; contrast; chick The developmental

  20. 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

  1. Designing and tuning magnetic resonance with exchange interaction.

    PubMed

    Chen, Yunpeng; Fan, Xin; Zhou, Yang; Xie, Yunsong; Wu, Jun; Wang, Tao; Chui, Siu Tat; Xiao, John Q

    2015-02-01

    Exchange interaction at the interface between magnetic layers exhibits significant contribution to the magnetic resonance frequency. The in situ tuning of the resonance frequency, as large as 10 GHz, is demonstrated in a spintronics microwave device through manipulating the interface exchange interaction. PMID:25572962

  2. Bioengineering 278: Magnetic Resonance Imaging Laboratory Winter 2010

    E-print Network

    California at San Diego, University of

    Bioengineering 278: Magnetic Resonance Imaging Laboratory Winter 2010 Lab 4 1. EPI. In this exercise, you will observe and correct the effects of time shifts and resonance offset in EPI. Place, in units of the sampling period. (6 points) b. Off resonance effects in EPI. In addition to the time shift

  3. 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.

  4. 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.

  5. Small-Volume Nuclear Magnetic Resonance Spectroscopy

    NASA Astrophysics Data System (ADS)

    Fratila, Raluca M.; Velders, Aldrik H.

    2011-07-01

    Nuclear magnetic resonance (NMR) spectroscopy is one of the most information-rich analytical techniques available. However, it is also inherently insensitive, and this drawback precludes the application of NMR spectroscopy to mass- and volume-limited samples. We review a particular approach to increase the sensitivity of NMR experiments, namely the use of miniaturized coils. When the size of the coil is reduced, the sample volume can be brought down to the nanoliter range. We compare the main coil geometries (solenoidal, planar, and microslot/stripline) and discuss their applications to the analysis of mass-limited samples. We also provide an overview of the hyphenation of microcoil NMR spectroscopy to separation techniques and of the integration with lab-on-a-chip devices and microreactors.

  6. 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

  7. Two-dimensional nuclear magnetic resonance petrophysics.

    PubMed

    Sun, Boqin; Dunn, Keh-Jim

    2005-02-01

    Two-dimensional nuclear magnetic resonance (2D NMR) opens a wide area for exploration in petrophysics and has significant impact to petroleum logging technology. When there are multiple fluids with different diffusion coefficients saturated in a porous medium, this information can be extracted and clearly delineated from CPMG measurements of such a system either using regular pulsing sequences or modified two window sequences. The 2D NMR plot with independent variables of T2 relaxation time and diffusion coefficient allows clear separation of oil and water signals in the rocks. This 2D concept can be extended to general studies of fluid-saturated porous media involving other combinations of two or more independent variables, such as chemical shift and T1/T2 relaxation time (reflecting pore size), proton population and diffusion contrast, etc. PMID:15833623

  8. Magnetic resonance imaging of knee cartilage repair.

    PubMed

    Gold, G E; Bergman, A G; Pauly, J M; Lang, P; Butts, R K; Beaulieu, C F; Hargreaves, B; Frank, L; Boutin, R D; Macovski, A; Resnick, D

    1998-12-01

    Cartilage injury resulting in osteoarthritis is a frequent cause of disability in young people. Osteoarthritis, based on either cartilage injury or degeneration, is a leading cause of disability in the United States. Over the last several decades, much progress has been made in understanding cartilage injury and repair. Magnetic resonance (MR) imaging, with its unique ability to noninvasively image and characterize soft tissue, has shown promise in assessment of cartilage integrity. In addition to standard MR imaging methods, MR imaging contrast mechanisms under development may reveal detailed information regarding the physiology and morphology of cartilage. MR imaging will play a crucial role in assessing the success or failure of therapies for cartilage injury and degeneration. PMID:9894740

  9. 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

  10. Interactive Course on Magnetic Resonance Imagining

    NSDL National Science Digital Library

    2013-01-01

    As the health care professions continue to attract talented individuals, online resources have become an attractive way to learn new skills and supplement classroom learning. This website offers interested parties a step-by-step, interactive course on magnetic resonance imaging (MRI). It's worth noting that the site has received several awards from organizations such as the Radiological Society of North America. The course is divided into 16 sections, including Cardiac MRI, Image Formation, and Functional MRI. Each section contains a table of contents and a detailed list of learning objectives. As a whole, the site is a great way to get acquainted with this important medical tool and it is a resource that educators will want to share with friends and colleagues. [KMG

  11. Magnetic resonance imaging of placenta accreta

    PubMed Central

    Varghese, Binoj; Singh, Navdeep; George, Regi A.N; Gilvaz, Sareena

    2013-01-01

    Placenta accreta (PA) is a severe pregnancy complication which occurs when the chorionic villi (CV) invade the myometrium abnormally. Optimal management requires accurate prenatal diagnosis. Ultrasonography (USG) and magnetic resonance imaging (MRI) are the modalities for prenatal diagnosis of PA, although USG remains the primary investigation of choice. MRI is a complementary technique and reserved for further characterization when USG is inconclusive or incomplete. Breath-hold T2-weighted half-Fourier rapid acquisition with relaxation enhancement (RARE) and balanced steady-state free precession imaging in the three orthogonal planes is the key MRI technique. Markedly heterogeneous placenta, thick intraplacental dark bands on half-Fourier acquisition single-shot turbo spin-echo (HASTE), and disorganized abnormal intraplacental vascularity are the cardinal MRI features of PA. MRI is less reliable in differentiating between different degrees of placental invasion, especially between accreta vera and increta. PMID:24604945

  12. Endometriosis: the role of magnetic resonance imaging.

    PubMed

    Saba, Luca; Sulcis, Rosa; Melis, Gian Benedetto; de Cecco, Carlo Nicola; Laghi, Andrea; Piga, Mario; Guerriero, Stefano

    2015-03-01

    Several imaging options are available today to diagnose endometriosis. Currently, the two techniques most used are sonography and magnetic resonance imaging (MRI). Three-dimensional (3D) sonography has proved to be particularly sensitive in the diagnosis of endometriosis. In recent years, MRI has emerged as a high reproducible method to explore endometriosis; moreover, its capability to evaluate tissue signal is an extremely powerful system in the differential diagnosis with other pathologies and for the identification of malignant degeneration. The purpose of this paper is to present the state-of-the-art of MRI of endometriosis by performing a review of the literature and showing the epidemiology, pathogenesis, and classification of endometriosis. In this work, the technique that should be used, MR findings of endometriosis and the principles of differential diagnosis are explained. PMID:24676084

  13. 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

  14. Magnetic resonance imaging for acute pancreatitis

    PubMed Central

    Xiao, Bo; Zhang, Xiao-Ming

    2010-01-01

    Acute pancreatitis is characterized by acute chemical injury of the pancreatic parenchyma and peripancreatic tissue. The increased frequency of death in acute pancreatitis is directly correlated with the degree and progress of pancreatic necrosis. Moreover, the occurrence of some local complications in acute pancreatitis, such as pancreatic hemorrhage, peripancreatic abscess or large pseudocyst, and pseudoaneurysm, could influence the choice of treatment for these patients. Magnetic resonance imaging (MRI) can be used to help evaluate the presence and degree of pancreatic necrosis, and is crucial for identifying complications of acute pancreatitis and predicting prognosis. The purpose of this article is to describe MRI techniques for acute pancreatitis, to review the spectrum of pancreatic and peripancreatic patterns, as well as to survey various complications secondary to acute pancreatitis on MRI. The role of MRI in the initial evaluation and staging of acute pancreatitis is emphasized. PMID:21160684

  15. Claustrophobia and the magnetic resonance imaging procedure.

    PubMed

    McIsaac, H K; Thordarson, D S; Shafran, R; Rachman, S; Poole, G

    1998-06-01

    We examined fear induced by the magnetic resonance imaging (MRI) procedure in 80 adult patients who were undergoing the procedure for the first time. Participants completed self-report measures of claustrophobia, anxiety sensitivity, thoughts about the scan, and pain. Participants were assessed pre- and postscan, and at 1-month follow-up. Twenty-five percent of the participants experienced moderate to severe anxiety during the MRI scan. Prescan scores on the Claustrophobia Questionnaire (CLQ: Rachman and Taylor, 1993) significantly predicted participants' distress during the scan: pain and anxeity sensitivity did not. Furthermore, CLQ scores discriminated between participants who reported panic during the scan and participants who did not report panic. A brief screening instrument consisting of six items from the 29-item CLQ is suggested. This brief screening instrument administered prior to the scan may help identify in advance those people who are most likely to experience claustrophobic fear and, in particular, those who panic during the MRI procedure. PMID:9642571

  16. 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.

  17. Magnetic resonance imaging after exposure to microgravity

    NASA Technical Reports Server (NTRS)

    Leblanc, Adrian

    1993-01-01

    A number of physiological changes were demonstrated in bone, muscle, and blood from 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. Historically, NASA has had to rely on tape measures, x-ray, and metabolic balance studies with collection of excreta and blood specimens to obtain this information. The development of magnetic resonance imaging (MRI) offers the possibility of greatly extending these early studies in ways not previously possible; MRI is also non-invasive and safe; i.e., no radiation exposure. MRI provides both superb anatomical images for volume measurements of individual structures and quantification of chemical/physical changes induced in the examined tissues. This investigation will apply MRI technology to measure muscle, intervertebral disc, and bone marrow changes resulting from exposure to microgravity.

  18. 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.

  19. Simulations of pulsed nuclear magnetic resonance experiments

    SciTech Connect

    Smith, S.A.

    1991-01-01

    In order to help elucidate various aspects of pulsed nuclear magnetic resonance (NMR) experiments in the liquid state, a consistent mathematical treatment based on density matrix formalism was developed and implemented in a computer program, RELAX. Relaxation effects stemming from dipolar, chemical shift anisotropy (CSA), and random field mechanisms are accounted for, including contributions from dipole-CSA cross-correlation. The program was utilized to study para-fluorophenyl spin systems in dynamical regimes characteristic of both small and large molecules. Theory demonstrates that dipole-CSA cross-correlation can have pronounced effects in these systems and suggests that analysis of these effects will be useful in the study of protein conformation and dynamics.

  20. 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.

  1. The Multisensory Attentional Consequences of Tool Use: A Functional Magnetic Resonance Imaging Study

    E-print Network

    Hansen, Peter

    The Multisensory Attentional Consequences of Tool Use: A Functional Magnetic Resonance Imaging of Oxford Centre for Clinical Magnetic Resonance Research, John Radcliffe Hospital, Headington, Oxford functional magnetic resonance imaging, while they used a simple tool to discriminate between target

  2. Magnetic resonance imaging of live freshwater mussels (Unionidae) F. Michael Holliman,1,a

    E-print Network

    Kwak, Thomas J.

    Magnetic resonance imaging of live freshwater mussels (Unionidae) F. Michael Holliman,1,a Denise 2 Magnetic Resonance Research Center, University of Pittsburgh Medical Center, Pittsburgh, Eastern elliptio Elliptio complanata, via magnetic resonance imaging (MRI), acquiring data with a widely

  3. Functional Mapping of Human Sensorimotor Cortex with 3D BOLD fMRI Correlates Highly With H215O PET rCBF

    Microsoft Academic Search

    Nick F. Ramsey; Brenda S. Kirkby; Peter Van Gelderen; Karen F. Berman; Jeff H. Duyn; Joe A. Frank; Venkata S. Mattay; John D. Van Horn; Giuseppe Esposito; Chrit T. W. Moonen; Daniel R. Weinberger; Daniel R Weinberger

    1996-01-01

    Positron emission tomography (PET) functional imaging is based on changes in regional cerebral blood flow (rCBF). Functional magnetic resonance imaging (fMRI) is based on a variety of physiological parameters as well as rCBF. This study is aimed at the cross validation of three-dimensional (3D) fMRI, which is sensitive to changes in blood oxygenation, with oxygen-15-labeled water (H215O) PET. Nine normal

  4. Magnetic resonance imaging of the knee.

    PubMed

    Jackson, D W; Jennings, L D; Maywood, R M; Berger, P E

    1988-01-01

    Magnetic resonance imaging (MRI) is an accepted non-invasive modality for evaluation of soft tissue pathology without exposure to ionizing radiation. Current applications demonstrate excellent visualization of the anatomy and pathology of various organs. Preliminary studies in the knee reveal fine resolution of anatomy and pathology involving the meniscus. The purpose of this study is to determine a prospective correlation between MRI scans and actual meniscal pathology as documented at the time of arthroscopy. MRI scans were obtained in 155 patients, on 156 knees (one patient with bilateral scans), with 86 patients (87 knees) eventually undergoing diagnostic and operative videoarthroscopy performed by the same surgeon (DWJ). All images were obtained on the same high-resolution 1.5 Tesla GE Signa Magnetic Resonance Scanner with the same radiologist performing all readings (PEB). The knees were studied in the coronal and sagittal plane using a spin echo sequence and 5 mm slice thicknesses. The menisci were described as having Grade 1, 2, or 3 changes, with Grade 3 reserved for complete tears. Using arthroscopy as the diagnostic standard, the accuracy of MRI in diagnosing medial and lateral meniscal tears was 93.1% and 96.6%, respectively with a Grade 3 MRI reading. For tears of the ACL, the accuracy was 96.6% as confirmed at arthroscopy. Five tears of the PCL were also documented by MRI and correlated with clinical evaluation. Other abnormalities seen were articular cartilage and osteochondral defects, bone tumors, tibial plateau fractures, Baker's cysts, and meniscal cysts. The MRI scan is a highly accurate, noninvasive modality for documentation of meniscal pathology as well as cruciate ligament tears in the knee. PMID:3344877

  5. 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

  6. ASA monitoring standards and magnetic resonance imaging.

    PubMed

    Jorgensen, N H; Messick, J M; Gray, J; Nugent, M; Berquist, T H

    1994-12-01

    Some patients, often because of age or altered mental state, require general anesthesia or monitored anesthesia care and sedation if adequate magnetic resonance imaging (MRI) is to be accomplished. This study evaluated whether patients can be monitored during MRI with 1.5-tesla scanners in a manner which complies with ASA monitoring standards without causing degradation of image quality. Ten volunteers were scanned in the MRI without sedation. Monitors meeting ASA standards were placed and electronic artifact produced by the magnetic resonance (MR) scanner was evaluated, after which two scans of the head and two of the chest were performed. One of each pair of scans was obtained with the monitors functioning and one with them turned off. Four radiologists, blinded as to whether the monitors were turned on or off, independently evaluated the 20 pairs of scans. Differences in diagnostic quality and image degradation between the scans were evaluated and scores assigned. All monitors functioned appropriately during the scans, with the exception of the electrocardiogram (ECG) which was grossly distorted to the extent that only ventricular rate could be evaluated. None of the head or body scans was nondiagnostic; however, images with the monitors off were of better quality overall than with them on. Two types of noise were generated and are described. During the head scans, three of seven monitoring combinations caused degradation of the images, while four were judged clinically adequate. During the body scans, two of six monitoring combinations created noticeable noise, while four introduced no significant noise. Ungated cardiac scans were nondiagnostic.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7978439

  7. Selectivity in multiple quantum nuclear magnetic resonance

    SciTech Connect

    Warren, W.S.

    1980-11-01

    The observation of multiple-quantum nuclear magnetic resonance transitions in isotropic or anisotropic liquids is shown to give readily interpretable information on molecular configurations, rates of motional processes, and intramolecular interactions. However, the observed intensity of high multiple-quantum transitions falls off dramatically as the number of coupled spins increases. The theory of multiple-quantum NMR is developed through the density matrix formalism, and exact intensities are derived for several cases (isotropic first-order systems and anisotropic systems with high symmetry) to shown that this intensity decrease is expected if standard multiple-quantum pulse sequences are used. New pulse sequences are developed which excite coherences and produce population inversions only between selected states, even though other transitions are simultaneously resonant. One type of selective excitation presented only allows molecules to absorb and emit photons in groups of n. Coherent averaging theory is extended to describe these selective sequences, and to design sequences which are selective to arbitrarily high order in the Magnus expansion. This theory and computer calculations both show that extremely good selectivity and large signal enhancements are possible.

  8. 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

  9. Relationship of Structural Magnetic Resonance Imaging, Magnetic Resonance Perfusion, and Other Disease Factors to Neuropsychological Outcome in Sickle Cell Disease

    Microsoft Academic Search

    Royal Grueneich; M. Douglas Ris; William Ball; Karen A. Kalinyak; Robert Noll; Kathy Vannatta; Robert Wells

    2004-01-01

    Objective To investigate the relationship between neuropsychological functioning and radiographic findings in children with sickle cell disease (SCD) with no history of clinical neurological events. Methods Thirty-one patients with SCD randomly selected from a regional treatment center underwent neuropsychological and disease severity assessments. Of these, 22 also had structural magnetic resonance imaging and magnetic resonance perfusion studies performed. Results Forty-five

  10. [Isoflurane in angiography with magnetic resonance].

    PubMed

    Carriero, A; Villa, A; Iezzi, A; Tamburri, L; Bosco, G; Bonomo, L

    1995-01-01

    The authors investigated if the use of vasodilating drugs could increase Magnetic Resonance angiography (MRA) capabilities in demonstrating intracranial vessels. Twenty patients (mean age: 10 years) were examined with MRA: a vasodilating drug (isoflurane) was administered to 10 of them and 10 matched-pair subjects were selected as controls and submitted to MRA without receiving any drug known to increase cerebral blood flow. MRA was performed with a 1.5-T superconductive magnet; FISP 3D sequences were used in all cases. A multiple choice card was used by a reader reporting the following diagnostic information for the different segments of the intracranial vessels: 1) hyperintense and homogeneous vessel with high signal-to-noise (S/N) ratio; 2) hyperintense and heterogeneous vessel with high S/N ratio; 3) hyperintense vessel with low S/N ratio; 4) poor vessels depiction. Small vessels (ophthalmic arteries, A3, M3, M4, anterior communicating arteries and P2 segments) were better demonstrated with isoflurane than with conventional MRA. The results were compared with the Mann-Withney test: isoflurane MRA allowed good vessel depiction in 127 cases, versus 83 of conventional MRA; the difference was statistically significant. To conclude, the use of vasodilating drugs represents a new research field in MRA of the intracranial vessels. PMID:7569104

  11. Designing Magnetic Resonance Imaging Curriculum for Undergraduates

    NSDL National Science Digital Library

    A new hands-on curriculum developed at Vanderbilt University focuses on teaching medical imaging, specifically magnetic resonance imaging(MRI). This material was designed to engage students in real world applications of biomedical engineering through challenge based activities. These activities include homework, quizzes, and hands-on experiments. The materials for each activity are easy to find and can be purchased for under $25. The curriculum begins with a Grand Challenge that presents a medical case in order to interest the students. The challenge questions allow the students to play the role of the patient, technician, and physician. The material was organized in five modules: Electromagnetic Fields and Magnetic Moments, Spin Behavior: Excitation and Relaxation, Spatial Encoding and Detecting Signals, Image Reconstruction, and Image Characteristics. In addition, there are expert interviews that provide the students with multiple perspectives on the information. The material was tested in the summer of 2007 on five students in order to gain feedback, correct errors, and gauge student understanding. Testing showed that the curriculum had a positive impact on student interest in biomedical imaging and resulted in several improvements and additions to the curriculum. During the academic year, the materials will be field-tested at the undergraduate and high school level. Additionally, the materials are being adapted for high school level implementation.

  12. 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.

  13. 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

  14. In vivo Off-Resonance Saturation Magnetic Resonance Imaging of AvB3-Targeted Superparamagnetic Nanoparticles

    E-print Network

    Gao, Jinming

    #12;In vivo Off-Resonance Saturation Magnetic Resonance Imaging of AvB3-Targeted Superparamagnetic of Texas Southwestern Medical Center, Dallas, Texas Abstract Magnetic resonance imaging is a powerful mechanisms and imaging probes have been actively pursued for cancer molecular imaging by magnetic resonance

  15. [Magnetic resonance contract agents and perfusion imaging].

    PubMed

    Benderbous, S; Bonnemain, B

    1996-01-01

    Contrast agents may be categorised as non-specific or specific agents. Non-specific agents are freely diffusible in the extracellular and extravascular compartment with the exception of the brain where only blood brain barrier lesions enables the contrast agent to pass. In the specific agent group, a new class of products has been developed, that of blood pool contrast agent, which are distributed in the total intravascular volume and are slowly cleared from the blood. Crossing the healthy capillary wall is limited and depends both on the pathological state of the endothelial permeability tissue of the organ under interest and on the characteristics of the contrast agent (size, charge, molecular shape...). The diagnostic efficacy in perfusion imaging including cerebral perfusion is modulated by the pharmacokinetic profile of the blood pool contrast agent. One way to improve the vascular residence time, consists in binding a vector such as synthetic polymer or a biological macromolecule and a lanthanide like Gd3+, Mn2+, Dy3+ or metal ions. A second way is the synthesis of ultrasmall iron oxide nanoparticles which could escape rapid recognition by the monocyte macrophage phagocytic system mainly of liver and spleen. Because of their cristalline structure and the large number of non-paired spins, five electrons for the iron metal, the nanoparticles behave as magnetic domain when an external field is applied. They consequently have a high dipolar magnetic moment, and can produce a T2 effect in vivo, resulting in a drop in the magnetic resonance signal. Possible interests and developments toward perfusion imaging are demonstrated in experimental models studies. PMID:8656086

  16. DIABETIC RETINOPATHY UPDATE Magnetic resonance imaging of the retina: A brief

    E-print Network

    Duong, Timothy Q.

    DIABETIC RETINOPATHY UPDATE Magnetic resonance imaging of the retina: A brief historical and future KEYWORDS MRI; Magnetic resonance imaging; Diabetic retinopathy; Retinitis pigmentosa; Glaucoma Abstract

  17. Bridging the Gap: Integrating Cellular and Functional Magnetic Resonance Imaging Studies

    E-print Network

    Rotstein, Horacio G.

    Bridging the Gap: Integrating Cellular and Functional Magnetic Resonance Imaging Studies and interpreting experimental results. The temporal and spatial resolution of functional magnetic resonance imaging

  18. 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

  19. MODELING IMAGE SEQUENCES, WITH PARTICULAR APPLICATION TO FMRI DATA

    E-print Network

    Hastie, Trevor

    MODELING IMAGE SEQUENCES, WITH PARTICULAR APPLICATION TO FMRI DATA a dissertation submitted resonance imaging (fMRI) has made it possible to conduct so- phisticated human brain mapping neuroscience replenishing the sites. The data collected in fMRI human brain mapping experiments consists of se- quences

  20. Joint sparse representation of brain activity patterns in multi-task fMRI data.

    PubMed

    Ramezani, M; Marble, K; Trang, H; Johnsrude, I S; Abolmaesumi, P

    2015-01-01

    A single-task functional magnetic resonance imaging (fMRI) experiment may only partially highlight alterations to functional brain networks affected by a particular disorder. Multivariate analysis across multiple fMRI tasks may increase the sensitivity of fMRI-based diagnosis. Prior research using multi-task analysis in fMRI, such as those that use joint independent component analysis (jICA), has mainly assumed that brain activity patterns evoked by different tasks are independent. This may not be valid in practice. Here, we use sparsity, which is a natural characteristic of fMRI data in the spatial domain, and propose a joint sparse representation analysis (jSRA) method to identify common information across different functional subtraction (contrast) images in data from a multi-task fMRI experiment. Sparse representation methods do not require independence, or that the brain activity patterns be nonoverlapping. We use functional subtraction images within the joint sparse representation analysis to generate joint activation sources and their corresponding sparse modulation profiles. We evaluate the use of sparse representation analysis to capture individual differences with simulated fMRI data and with experimental fMRI data. The experimental fMRI data was acquired from 16 young (age: 19-26) and 16 older (age: 57-73) adults obtained from multiple speech comprehension tasks within subjects, where an independent measure (namely, age in years) can be used to differentiate between groups. Simulation results show that this method yields greater sensitivity, precision, and higher Jaccard indexes (which measures similarity and diversity of the true and estimated brain activation sources) than does the jICA method. Moreover, superiority of the jSRA method in capturing individual differences was successfully demonstrated using experimental fMRI data. PMID:25073167