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1

Diffusion microscopist simulator: a general monte carlo simulation system for diffusion magnetic resonance imaging.  

PubMed

This article describes the development and application of an integrated, generalized, and efficient Monte Carlo simulation system for diffusion magnetic resonance imaging (dMRI), named Diffusion Microscopist Simulator (DMS). DMS comprises a random walk Monte Carlo simulator and an MR image synthesizer. The former has the capacity to perform large-scale simulations of Brownian dynamics in the virtual environments of neural tissues at various levels of complexity, and the latter is flexible enough to synthesize dMRI datasets from a variety of simulated MRI pulse sequences. The aims of DMS are to give insights into the link between the fundamental diffusion process in biological tissues and the features observed in dMRI, as well as to provide appropriate ground-truth information for the development, optimization, and validation of dMRI acquisition schemes for different applications. The validity, efficiency, and potential applications of DMS are evaluated through four benchmark experiments, including the simulated dMRI of white matter fibers, the multiple scattering diffusion imaging, the biophysical modeling of polar cell membranes, and the high angular resolution diffusion imaging and fiber tractography of complex fiber configurations. We expect that this novel software tool would be substantially advantageous to clarify the interrelationship between dMRI and the microscopic characteristics of brain tissues, and to advance the biophysical modeling and the dMRI methodologies. PMID:24130783

Yeh, Chun-Hung; Schmitt, Benoît; Le Bihan, Denis; Li-Schlittgen, Jing-Rebecca; Lin, Ching-Po; Poupon, Cyril

2013-10-10

2

Diffusion Microscopist Simulator: A General Monte Carlo Simulation System for Diffusion Magnetic Resonance Imaging  

PubMed Central

This article describes the development and application of an integrated, generalized, and efficient Monte Carlo simulation system for diffusion magnetic resonance imaging (dMRI), named Diffusion Microscopist Simulator (DMS). DMS comprises a random walk Monte Carlo simulator and an MR image synthesizer. The former has the capacity to perform large-scale simulations of Brownian dynamics in the virtual environments of neural tissues at various levels of complexity, and the latter is flexible enough to synthesize dMRI datasets from a variety of simulated MRI pulse sequences. The aims of DMS are to give insights into the link between the fundamental diffusion process in biological tissues and the features observed in dMRI, as well as to provide appropriate ground-truth information for the development, optimization, and validation of dMRI acquisition schemes for different applications. The validity, efficiency, and potential applications of DMS are evaluated through four benchmark experiments, including the simulated dMRI of white matter fibers, the multiple scattering diffusion imaging, the biophysical modeling of polar cell membranes, and the high angular resolution diffusion imaging and fiber tractography of complex fiber configurations. We expect that this novel software tool would be substantially advantageous to clarify the interrelationship between dMRI and the microscopic characteristics of brain tissues, and to advance the biophysical modeling and the dMRI methodologies.

Yeh, Chun-Hung; Schmitt, Benoit; Le Bihan, Denis; Li-Schlittgen, Jing-Rebecca; Lin, Ching-Po; Poupon, Cyril

2013-01-01

3

Quantitative magnetic resonance imaging of brain development in premature and mature newborns  

Microsoft Academic Search

Definition in the living premature infant of the anatomical and temporal characteristics of development of critical brain structures is crucial for insight into the time of greatest vulnerability of such brain structures. We utilized 3D Magnetic Resonance Imaging (3D-MRI) and image processing algorithms to quantitate total brain volume and total volumes of cerebral gray matter (GM), unmyelinated white matter (WM),

Simon Warfield; Ron Kikinis; Patrick D. Barnes; Gary P. Zientara; Ferenc A. Jolesz; Miles K. Tsuji; Joseph J. Volpe

1998-01-01

4

Magnetic Resonance Imaging (MRI).  

National Technical Information Service (NTIS)

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

E. Feigenbaum

1985-01-01

5

Magnetic resonance imaging and spectroscopy  

SciTech Connect

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

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

1986-01-01

6

Magnetic resonance imaging  

SciTech Connect

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

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

1988-01-01

7

Clinical magnetic resonance imaging  

SciTech Connect

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

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

1988-01-01

8

Magnetic Resonance Imaging  

NSDL National Science Digital Library

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

VU Bioengineering RET Program, School of Engineering,

9

NOTE: Four-dimensional magnetic resonance imaging for the determination of tumour movement and its evaluation using a dynamic porcine lung phantom  

NASA Astrophysics Data System (ADS)

A method of four-dimensional (4D) magnetic resonance imaging (MRI) has been implemented and evaluated. It consists of retrospective sorting and slice stacking of two-dimensional (2D) images using an external signal for motion monitoring of the object to be imaged. The presented method aims to determine the tumour trajectories based on a signal that is appropriate for monitoring the movement of the target volume during radiotherapy such that the radiation delivery can be adapted to the movement. For evaluation of the 4D-MRI method, it has been applied to a dynamic lung phantom, which exhibits periodic respiratory movement of a porcine heart-lung explant with artificial pulmonary nodules. Anatomic changes of the lung phantom caused by respiratory motion have been quantified, revealing hysteresis. The results demonstrate the feasibility of the presented method of 4D-MRI. In particular, it enables the determination of trajectories of periodically moving objects with an uncertainty in the order of 1 mm.

Remmert, G.; Biederer, J.; Lohberger, F.; Fabel, M.; Hartmann, G. H.

2007-09-01

10

Magnetic resonance imaging in medicine  

Microsoft Academic Search

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

Stephen F. Keevil

2001-01-01

11

Orthopaedic Magnetic Resonance Imaging Challenge  

PubMed Central

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

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

2010-01-01

12

Magnetic resonance imaging  

SciTech Connect

The author succeeds in making the physical phenomena of MR imaging quite comprehensible. The chapters on imaging sequences and parameters and the effects of pathologic conditions on MR images are written in a way that helps the beginner. MR artifacts are discussed in a special chapter. The atlas, which makes up 60% of the book; includes a detailed imaging guide with protocols concentrating mainly on the head, neck and brain. MR imaging of the chest is discussed as well as abdomen, pelvis and hips, and the spine, breast, and knee. The book ends with a list of MR equipment manufacturers, specifications of nine major commercial MR imagers, and a glossary of MR terminology.

Elster, A.D.

1986-01-01

13

Magnetic Resonance Reporter Gene Imaging  

PubMed Central

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

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

2012-01-01

14

Transesophageal magnetic resonance imaging  

Microsoft Academic Search

The purpose of this study was to develop a non-invasive method of imaging the thoracic aorta that would provide both morpho- logical detail within the aortic wall and information about regional aortic wall motion. An esophageal probe is described that allows transesophageal MR imaging (TEMRI) of the thoracic aorta and has several potential advantages over the competing non-vasculoinvasive techniques of

Kendrick A. Shunk; Joao A. C. Lima; Alan W. Heldman; Ergin Atalar

1999-01-01

15

Spatiotemporal spiral magnetic resonance imaging  

NASA Astrophysics Data System (ADS)

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

Soumekh, Mehrdad

1999-05-01

16

Metabolic brain imaging by magnetic resonance  

Microsoft Academic Search

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

Edward J Novotny Jr

2006-01-01

17

Interventional Cardiovascular Magnetic Resonance Imaging  

PubMed Central

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

Saikus, Christina E.; Lederman, Robert J.

2010-01-01

18

Magnetic resonance imaging of acquired cardiac disease.  

PubMed Central

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

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

1996-01-01

19

[Magnetic resonance imaging elbow anatomy].  

PubMed

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

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

20

PANDA: a pipeline toolbox for analyzing brain diffusion images  

PubMed Central

Diffusion magnetic resonance imaging (dMRI) is widely used in both scientific research and clinical practice in in-vivo studies of the human brain. While a number of post-processing packages have been developed, fully automated processing of dMRI datasets remains challenging. Here, we developed a MATLAB toolbox named “Pipeline for Analyzing braiN Diffusion imAges” (PANDA) for fully automated processing of brain diffusion images. The processing modules of a few established packages, including FMRIB Software Library (FSL), Pipeline System for Octave and Matlab (PSOM), Diffusion Toolkit and MRIcron, were employed in PANDA. Using any number of raw dMRI datasets from different subjects, in either DICOM or NIfTI format, PANDA can automatically perform a series of steps to process DICOM/NIfTI to diffusion metrics [e.g., fractional anisotropy (FA) and mean diffusivity (MD)] that are ready for statistical analysis at the voxel-level, the atlas-level and the Tract-Based Spatial Statistics (TBSS)-level and can finish the construction of anatomical brain networks for all subjects. In particular, PANDA can process different subjects in parallel, using multiple cores either in a single computer or in a distributed computing environment, thus greatly reducing the time cost when dealing with a large number of datasets. In addition, PANDA has a friendly graphical user interface (GUI), allowing the user to be interactive and to adjust the input/output settings, as well as the processing parameters. As an open-source package, PANDA is freely available at http://www.nitrc.org/projects/panda/. This novel toolbox is expected to substantially simplify the image processing of dMRI datasets and facilitate human structural connectome studies.

Cui, Zaixu; Zhong, Suyu; Xu, Pengfei; He, Yong; Gong, Gaolang

2013-01-01

21

PANDA: a pipeline toolbox for analyzing brain diffusion images.  

PubMed

Diffusion magnetic resonance imaging (dMRI) is widely used in both scientific research and clinical practice in in-vivo studies of the human brain. While a number of post-processing packages have been developed, fully automated processing of dMRI datasets remains challenging. Here, we developed a MATLAB toolbox named "Pipeline for Analyzing braiN Diffusion imAges" (PANDA) for fully automated processing of brain diffusion images. The processing modules of a few established packages, including FMRIB Software Library (FSL), Pipeline System for Octave and Matlab (PSOM), Diffusion Toolkit and MRIcron, were employed in PANDA. Using any number of raw dMRI datasets from different subjects, in either DICOM or NIfTI format, PANDA can automatically perform a series of steps to process DICOM/NIfTI to diffusion metrics [e.g., fractional anisotropy (FA) and mean diffusivity (MD)] that are ready for statistical analysis at the voxel-level, the atlas-level and the Tract-Based Spatial Statistics (TBSS)-level and can finish the construction of anatomical brain networks for all subjects. In particular, PANDA can process different subjects in parallel, using multiple cores either in a single computer or in a distributed computing environment, thus greatly reducing the time cost when dealing with a large number of datasets. In addition, PANDA has a friendly graphical user interface (GUI), allowing the user to be interactive and to adjust the input/output settings, as well as the processing parameters. As an open-source package, PANDA is freely available at http://www.nitrc.org/projects/panda/. This novel toolbox is expected to substantially simplify the image processing of dMRI datasets and facilitate human structural connectome studies. PMID:23439846

Cui, Zaixu; Zhong, Suyu; Xu, Pengfei; He, Yong; Gong, Gaolang

2013-02-21

22

Magnetic resonance imaging: Principles and applications  

SciTech Connect

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

Kean, D.; Smith, M.

1986-01-01

23

Pocket atlas of cranial magnetic resonance imaging  

SciTech Connect

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

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

1986-01-01

24

Neuronal current distribution imaging using magnetic resonance  

Microsoft Academic Search

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

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

1999-01-01

25

Other magnetic resonance imaging techniques.  

PubMed

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

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

2011-09-01

26

Imaging agents for in vivo magnetic resonance and scintigraphic imaging  

DOEpatents

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

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

1991-04-23

27

Magnetic Resonance Imaging Studies of Process Rheology.  

National Technical Information Service (NTIS)

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

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

1988-01-01

28

Coronary computed tomography and magnetic resonance imaging.  

PubMed

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

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

2009-04-01

29

Coronary Computed Tomography and Magnetic Resonance Imaging  

PubMed Central

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

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

2009-01-01

30

Can magnetic resonance imaging differentiate undifferentiated arthritis?  

PubMed Central

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

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

2005-01-01

31

A Primer on Functional Magnetic Resonance Imaging  

Microsoft Academic Search

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

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

2007-01-01

32

Functional Magnetic Resonance Imaging in Nursing Research  

Microsoft Academic Search

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

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

2006-01-01

33

Magnetic Resonance Imaging in Biomedical Engineering  

NASA Astrophysics Data System (ADS)

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

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

2007-11-01

34

Small Animal Imaging with Magnetic Resonance Microscopy  

Microsoft Academic Search

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

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

2008-01-01

35

Texture analysis methodologies for magnetic resonance imaging  

PubMed Central

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

Materka, Andrzej

2004-01-01

36

Magnetic Field Issues in Magnetic Resonance Imaging  

Microsoft Academic Search

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

Labros Spiridon Petropoulos

1993-01-01

37

Brain Morphometry Using Anatomical Magnetic Resonance Imaging  

ERIC Educational Resources Information Center

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

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

2008-01-01

38

Diffusion-weighted magnetic resonance imaging.  

PubMed

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

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

2002-06-01

39

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

ERIC Educational Resources Information Center

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

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

2000-01-01

40

Functional magnetic resonance imaging studies of language  

Microsoft Academic Search

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

Steven L. Small; Martha W. Burton

2002-01-01

41

In vitro quantitative ((1))H and ((19))F nuclear magnetic resonance spectroscopy and imaging studies of fluvastatin™ in Lescol® XL tablets in a USP-IV dissolution cell.  

PubMed

Swellable polymeric matrices are key systems in the controlled drug release area. Currently, the vast majority of research is still focused on polymer swelling dynamics. This study represents the first quantitative multi-nuclear (((1))H and ((19))F) fast magnetic resonance imaging study of the complete dissolution process of a commercial (Lescol® XL) tablet, whose formulation is based on the hydroxypropyl methylcellulose (HPMC) polymer under in vitro conditions in a standard USP-IV (United States Pharmacopeia apparatus IV) flow-through cell that is incorporated into high field superconducting magnetic resonance spectrometer. Quantitative RARE ((1))H magnetic resonance imaging (MRI) and ((19))F nuclear magnetic resonance (NMR) spectroscopy and imaging methods have been used to give information on: (i) dissolution media uptake and hydrodynamics; (ii) active pharmaceutical ingredient (API) mobilisation and dissolution; (iii) matrix swelling and dissolution and (iv) media activity within the swelling matrix. In order to better reflect the in vivo conditions, the bio-relevant media Simulated Gastric Fluid (SGF) and Fasted State Simulated Intestinal Fluid (FaSSIF) were used. A newly developed quantitative ultra-fast MRI technique was applied and the results clearly show the transport dynamics of media penetration and hydrodynamics along with the polymer swelling processes. The drug dissolution and mobility inside the gel matrix was characterised, in parallel to the ((1))H measurements, by ((19))F NMR spectroscopy and MRI, and the drug release profile in the bulk solution was recorded offline by UV spectrometer. We found that NMR spectroscopy and 1D-MRI can be uniquely used to monitor the drug dissolution/mobilisation process within the gel layer, and the results from ((19))F NMR spectra indicate that in the gel layer, the physical mobility of the drug changes from "dissolved immobilised drug" to "dissolved mobilised drug". PMID:21911016

Zhang, Qilei; Gladden, Lynn; Avalle, Paolo; Mantle, Michael

2011-09-03

42

Magnetic resonance imaging of the cervix  

PubMed Central

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

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

2007-01-01

43

A bandwidth indicator for magnetic resonance imagers.  

PubMed

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

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

1997-05-01

44

Nanoscale Fourier-Transform Magnetic Resonance Imaging  

NASA Astrophysics Data System (ADS)

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

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

2013-07-01

45

Granular convection observed by magnetic resonance imaging  

NASA Astrophysics Data System (ADS)

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

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

1995-03-01

46

Magnetic resonance imaging of shoulder arthropathies.  

PubMed

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

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

2012-02-16

47

Nuclear magnetic resonance imaging - Potential cardiac applications  

SciTech Connect

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

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

1980-12-18

48

Cardiovascular magnetic resonance imaging in small animals.  

PubMed

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

Botnar, René M; Makowski, Marcus R

2012-01-01

49

Magnetic resonance imaging in Mexico  

NASA Astrophysics Data System (ADS)

MR imaging has experienced an important growth worldwide and in particular in the USA and Japan. This imaging technique has also shown an important rise in the number of MR imagers in Mexico. However, the development of MRI has followed a typical way of Latin American countries, which is very different from the path shown in the industrialised countries. Despite the fact that Mexico was one the very first countries to install and operate MR imagers in the world, it still lacks of qualified clinical and technical personnel. Since the first MR scanner started to operate, the number of units has grown at a moderate space that now sums up approximately 60 system installed nationwide. Nevertheless, there are no official records of the number of MR units operating, physicians and technicians involved in this imaging modality. The MRI market is dominated by two important companies: General Electric (approximately 51%) and Siemens (approximately 17.5%), the rest is shared by other five companies. According to the field intensity, medium-field systems (0.5 Tesla) represent 60% while a further 35% are 1.0 T or higher. Almost all of these units are in private hospitals and clinics: there is no high-field MR imagers in any public hospital. Because the political changes in the country, a new public plan for health care is still in the process and will be published soon this year. This plan will be determined by the new Congress. North American Free Trade Agreement (NAFTA) and president Fox. Experience acquired in the past shows that the demand for qualified professionals will grow in the new future. Therefore, systematic training of clinical and technical professionals will be in high demand to meet the needs of this technique. The National University (UNAM) and the Metropolitan University (UAM-Iztapalapa) are collaborating with diverse clinical groups in private facilities to create a systematic training program and carry out research and development in MRI .

Rodriguez, A. O.; Rojas, R.; Barrios, F. A.

2001-10-01

50

Magnetic resonance imaging of the elbow. Part I: Normal anatomy, imaging technique, and osseous abnormalities  

Microsoft Academic Search

Part I of this comprehensive review on magnetic resonance imaging of the elbow discusses normal elbow anatomy and the technical factors involved in obtaining high-quality magnetic resonance images of the elbow. Part I also discusses the role of magnetic resonance imaging in evaluating patients with osseous abnormalities of the elbow. With proper patient positioning and imaging technique, magnetic resonance imaging

Richard Kijowski; Michael Tuite; Matthew Sanford

2004-01-01

51

Cardiac magnetic resonance imaging in Turner syndrome.  

PubMed

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

Gutmark-Little, Iris; Backeljauw, Philippe F

2013-05-01

52

Fat Segmentation in Magnetic Resonance Images  

Microsoft Academic Search

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

David P. Costello; Patrick A. Kenny

53

Magnetic resonance imaging in radiotherapy treatment planning  

Microsoft Academic Search

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

Marinus Adriaan Moerland

1996-01-01

54

Neurosurgical uses for intraprocedural magnetic resonance imaging.  

PubMed

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

Mutchnick, Ian S; Moriarty, Thomas M

2005-10-01

55

Magnetic Resonance Imaging (MRI): Brain  

MedlinePLUS

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

56

HOSPITAL PHYSICS: Magnetic resonance imaging and spectroscopy  

NASA Astrophysics Data System (ADS)

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

Andrews, Caroline; Simmons, Andrew; Williams, Steve

1996-03-01

57

Focal renal masses: magnetic resonance imaging  

SciTech Connect

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

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

1984-08-01

58

Surface Plasmon Resonance Imaging System and Method.  

National Technical Information Service (NTIS)

A surface plasmon resonance imaging system (40) and method is provided. The system (40) includes a light source (42) comprising a light-emitting diode (LED) array that is positioned at the focal point of a collimating lens (44). The light source (42) and ...

T. M. Chinowsky

2004-01-01

59

Respiratory gating of magnetic resonance images  

Microsoft Academic Search

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

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

1984-01-01

60

Magnetic resonance imaging of the elbow  

Microsoft Academic Search

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

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

1997-01-01

61

Magnetic resonance imaging in obstructive Müllerian anomalies.  

PubMed

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

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

2013-04-01

62

Magnetic resonance imaging in motor neuron disease  

Microsoft Academic Search

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

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

1990-01-01

63

Intraoperative Magnetic Resonance Imaging Safety Considerations  

Microsoft Academic Search

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

Lori Russell

2003-01-01

64

Coolant quality for magnetic resonance imaging systems  

Microsoft Academic Search

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

Julie Wong; Garron K Morris

2008-01-01

65

Magnetic resonance imaging of pelvic organ prolapse  

Microsoft Academic Search

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

H. K. Pannu; Russell H. Morgan

2002-01-01

66

Magnetic resonance imaging of painful shoulder arthroplasty  

Microsoft Academic Search

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

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

2002-01-01

67

Magnetic Resonance Imaging Methods in Soil Science  

Microsoft Academic Search

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

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

2009-01-01

68

Sports health magnetic resonance imaging challenge.  

PubMed

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

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

2010-11-01

69

Magnetic Resonance Imaging (MRI) of the Kidney.  

National Technical Information Service (NTIS)

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

L. Te Strake

1987-01-01

70

3D-Computerized facial reconstructions from 3D-MRI of human heads using deformable model approach  

Microsoft Academic Search

The aim of facial reconstruction is to estimate the face of an unknown individual from the shape of his\\/her skull to aid in recognition and identification. In this paper a 3D computerized facial reconstruction method from 3D-MRI of human heads is presented. It based on a model deformable approach constrained by the knowledge of soft tissues thicknesses, at a certain

Adel Kermi; S. Marniche-Kermi; M. T. Laskri

2010-01-01

71

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

Microsoft Academic Search

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

R. V. Mulkern; T. Chung

2000-01-01

72

Magnetic resonance perfusion imaging without contrast media  

Microsoft Academic Search

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

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

2010-01-01

73

Magnetic Resonance Imaging of Glutamate  

PubMed Central

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

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

2011-01-01

74

Magnetic resonance imaging of a mediastinal ependymoma.  

PubMed

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

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

1998-09-01

75

Functional magnetic resonance imaging (FMRI) of the human brain  

Microsoft Academic Search

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

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

1994-01-01

76

Magnetic resonance-compatible-spirometry: principle, technical evaluation and application.  

PubMed

The aim of this study was to assess the feasibility and accuracy of a novel magnetic resonance-compatible (MRc)-spirometer. The influence of body posture, magnetic resonance (MR)-setting and image acquisition on lung function was evaluated. Dynamic MR imaging (dMRI) was compared with simultaneously measured lung function. The development of the MRc-spirometer was based on a commercial spirometer and evaluated by flow-generator measurements and forced expiratory manoeuvres in 34 healthy nonsmokers (17 females and 17 males, mean age 32.9 yrs). Mean differences between forced expiratory volume in one second (FEV(1)) and forced vital capacity (FVC) were calculated and a sample paired t-test and Bland-Altman plots were generated. A total of 11 subjects underwent different subsequent MRc-spirometric measurements to assess the influence of the components of the MR system on lung function. The mean (95% confidence interval) difference of FEV(1) and FVC between the two systems was 0.004 (-0.04-0.04) L and 0.018 (-0.05-0.09) L, respectively. In the subgroup analysis, an influence of the MR-system on FEV(1) was found. FEV(1) correlated well with the dMRI measurement of the apico-diaphragmatic distance-change after the first second of forced expiration (r = 0.72). In conclusion, magnetic resonance-compatible-spirometry is feasible, reliable and safe. The magnetic resonance-setting only has a small influence on simultaneously measured forced expiratory volume in one second. Dynamic magnetic resonance imaging measurements correlate well with simultaneously acquired lung function parameters. PMID:17715166

Eichinger, M; Puderbach, M; Smith, H-J; Tetzlaff, R; Kopp-Schneider, A; Bock, M; Biederer, J; Kauczor, H-U

2007-08-22

77

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

Microsoft Academic Search

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

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

2001-01-01

78

Targeted-ROI imaging in electron paramagnetic resonance imaging.  

PubMed

Electron paramagnetic resonance imaging (EPRI) is a technique that has been used for in vivo oxygen imaging of small animals. In continuous wave (CW) EPRI, the measurement can be interpreted as a sampled 4D Radon transform of the image function. The conventional filtered-backprojection (FBP) algorithm has been used widely for reconstructing images from full knowledge of the Radon transform acquired in CW EPRI. In practical applications of CW EPRI, one often is interested in information only in a region of interest (ROI) within the imaged subject. It is desirable to accurately reconstruct an ROI image only from partial knowledge of the Radon transform because acquisition of the partial data set can lead to considerable reduction of imaging time. The conventional FBP algorithm cannot, however, reconstruct accurate ROI images from partial knowledge of the Radon transform of even dimension. In this work, we describe two new algorithms, which are referred to as the backprojection filtration (BPF) and minimum-data filtered-backprojection (MDFBP) algorithms, for accurate ROI-image reconstruction from a partial Radon transform (or, truncated Radon transform) in CW EPRI. We have also performed numerical studies in the context of ROI-image reconstruction of a synthetic 2D image with density similar to that found in a small animal EPRI. This demonstrates both the inadequacy of the conventional FBP algorithm and the success of BPF and MDFBP algorithms in ROI reconstruction. The proposed ROI imaging approach promises a means to substantially reduce image acquisition time in CW EPRI. PMID:17451981

Pan, Xiaochuan; Xia, Dan; Halpern, Howard

2007-02-23

79

BOLD magnetic resonance imaging of skeletal muscle.  

PubMed

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

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

2003-12-01

80

Multiparametric magnetic resonance imaging of prostate cancer  

PubMed Central

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

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

2012-01-01

81

Sensorineural Hearing Loss after Magnetic Resonance Imaging  

PubMed Central

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

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

2013-01-01

82

Magnetic Resonance Imaging Studies of Cigarette Smoking  

Microsoft Academic Search

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

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

83

Magnetic resonance imaging of palindromic rheumatism  

Microsoft Academic Search

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

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

2008-01-01

84

Magnetic resonance imaging of the fetus  

Microsoft Academic Search

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

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

1998-01-01

85

Magnetic resonance imaging evaluation of myocardial perfusion  

Microsoft Academic Search

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

Roberto Passariello; Marcello De Santis

1998-01-01

86

Predicting anxiety in magnetic resonance imaging scans  

Microsoft Academic Search

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

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

2004-01-01

87

magnetic resonance imaging: anthropometric relationships?3  

Microsoft Academic Search

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

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

88

Claustrophobia and the Magnetic Resonance Imaging Procedure  

Microsoft Academic Search

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

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

1998-01-01

89

Magnetic Resonance Imaging of the Kidney  

Microsoft Academic Search

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

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

90

Proton Magnetic Resonance Imaging of Flowing Blood.  

NASA Astrophysics Data System (ADS)

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

Du, Leila Ning-Zhi

1987-09-01

91

Magnetic resonance imaging. Application to family practice.  

PubMed Central

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

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

1999-01-01

92

Metabolic Tumor Imaging Using Magnetic Resonance Spectroscopy  

PubMed Central

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

Glunde, Kristine; Bhujwalla, Zaver M.

2011-01-01

93

Magnetic resonance imaging: present and future applications  

PubMed Central

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

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

1985-01-01

94

Imaging electrical resonance in hair cells  

PubMed Central

The mechanosensory hair cells of many auditory receptor organs are tuned by an electrical resonance that increases their responses to stimulation over a narrow band of frequencies. The small oscillations of membrane potential characteristic of this phenomenon have previously been detectable only through intracellular electrode measurements, which are laborious and preclude analysis at the level of an entire sensory organ. We used a voltage-sensitive dye to image hair-cell electrical resonance in an intact preparation of the bullfrog's sacculus, a receptor organ sensitive to low-frequency seismic and auditory stimuli. Imaging revealed distinct populations of hair cells whose resonant response varied with the frequency of transepithelial electrical stimulation. Most of the hair cells in the saccular epithelium in vitro were electrically tuned to stimulation at 25–50 Hz. The frequency dependence of the fluorescence signal was sensitive to pharmacological blockade of large-conductance Ca2+-sensitive K+ channels and to enzymatic digestion. At an elevated concentration of Ca2+, we observed transient fluorescence signals that probably represented action potentials. The stroboscopic imaging and analysis techniques described here present a general approach for studying subthreshold oscillations in electrically excitable cells.

Fisher, Jonathan A. N.; Kowalik, Lukasz; Hudspeth, A. J.

2011-01-01

95

Imaging electrical resonance in hair cells.  

PubMed

The mechanosensory hair cells of many auditory receptor organs are tuned by an electrical resonance that increases their responses to stimulation over a narrow band of frequencies. The small oscillations of membrane potential characteristic of this phenomenon have previously been detectable only through intracellular electrode measurements, which are laborious and preclude analysis at the level of an entire sensory organ. We used a voltage-sensitive dye to image hair-cell electrical resonance in an intact preparation of the bullfrog's sacculus, a receptor organ sensitive to low-frequency seismic and auditory stimuli. Imaging revealed distinct populations of hair cells whose resonant response varied with the frequency of transepithelial electrical stimulation. Most of the hair cells in the saccular epithelium in vitro were electrically tuned to stimulation at 25-50 Hz. The frequency dependence of the fluorescence signal was sensitive to pharmacological blockade of large-conductance Ca(2+)-sensitive K(+) channels and to enzymatic digestion. At an elevated concentration of Ca(2+), we observed transient fluorescence signals that probably represented action potentials. The stroboscopic imaging and analysis techniques described here present a general approach for studying subthreshold oscillations in electrically excitable cells. PMID:21220326

Fisher, Jonathan A N; Kowalik, Lukasz; Hudspeth, A J

2011-01-10

96

Magnetic resonance imaging of chest wall lesions.  

PubMed Central

Magnetic resonance imaging (MRI) demonstrates surface anatomy, nerves, and soft tissue pathology. Selective placement of the cursor lines in MRI displays specific anatomy. The MR images can then be used as adjunct in teaching surface anatomy to medical students and to other health professionals. Because the normal surface anatomy could be imaged at UCLA's radiology department, it was decided to image soft tissue abnormalities with MR to assist in patient care. Patients imaged were scheduled for special procedures of the chest or staging lymphangiograms. Patients were placed into categories depending on known diagnosis or interesting clinical presentation. The diagnostic categories included Hodgkin's disease, melanoma, carcinomas (eg, lung or breast), lymphedema, sarcomas, dermatological disorders, and neurological disorders. All images were orchestrated by the radiologist. This article discusses both the teaching and clinical impact on patient care. Images Figures 1A-B Figure 2 Figure 3 Figure 4 Figure 5 Figures 6A-B Figure 7 Figure 8 Figures 9A-B Figure 10

Collins, J. D.; Shaver, M.; Batra, P.; Brown, K.; Disher, A. C.

1991-01-01

97

Stem cell labeling for magnetic resonance imaging.  

PubMed

In vivo applications of cells for the monitoring of their cell dynamics increasingly use non-invasive magnetic resonance imaging. This imaging modality allows in particular to follow the migrational activity of stem cells intended for cell therapy strategies. All these approaches require the prior labeling of the cells under investigation for excellent contrast against the host tissue background in the imaging modality. The present review discusses the various routes of cell labeling and describes the potential to observe both cell localization and their cell-specific function in vivo. Possibilities for labeling strategies, pros and cons of various contrast agents are pointed out while potential ambiguities or problems of labeling strategies are emphasized. PMID:18465447

Himmelreich, Uwe; Hoehn, Mathias

2008-01-01

98

Nuclear magnetic resonance imaging in medicine  

PubMed Central

Using the technique of nuclear magnetic resonance (NMR, MR, MRI), the first images displaying pathology in humans were published in 1980.1 Since then, there has been a rapid extension in the use of the technique, with an estimated 225 machines in use in the USA at the end of 1985.2 Considerable enthusiasm has been expressed for this new imaging technique,3 although awareness of its high cost in the present economic climate has led to reservations being expressed in other quarters.2 The aim of this article is to give an outline of the present state of NMR, and indicate some possible future developments. ImagesFig 1Fig 2Fig 3(a)Fig 3 (b)Fig 4Fig 5Fig 6Fig 7 (a)Fig 7 (b)Fig 8Fig 9Fig 10

McKinstry, C S

1986-01-01

99

Cardiovascular Magnetic Resonance Imaging in Experimental Models  

PubMed Central

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

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

2010-01-01

100

Nuclear magnetic resonance imaging of the kidney  

SciTech Connect

The role of nuclear magnetic resonance (NMR) imaging of the kidney was analyzed in 18 persons (6 normal volunteers, 3 patients with pelvocaliectasis, 2 with peripelvic cysts, 1 with renal sinus lipomatosis, 3 with renal failure, 1 with glycogen storage disease, and 2 with polycystic kidney disease). Ultrasound and/or computed tomography (CT) studies were available for comparison in every case. In the normal kidney distinct anatomical structures were clearly differentiated by NMR. The best anatomical detail ws obtained with spin echo (SE) imaging, using a pulse sequence interval of 1,000 msec and an echo delay time of 28 msec. However, in the evaluation of normal and pathological conditions, all four intensity images (SE 500/28, SE 500/56, SE 1,000/28, and SE 1,000/56) have to be analyzed. No definite advantage was found in using SE imaging with a pulse sequence interval of 1,500 msec. Inversion recovery imaging enhanced the differences between the cortex and medulla, but it had a low signal-to-noise level and, therefore, a suboptimal overall resolution. The advantages of NMR compared with CT and ultrasound are discussed, and it is concluded that NMR imaging will prove to be a useful modality in the evaluation of renal disease.

Hricak, H.; Crooks, L.; Sheldon, P.; Kaufman, L.

1983-02-01

101

Mode Shape Measurement of Piezoelectric Resonators Using Image Processing Technique  

Microsoft Academic Search

An image processing technique for measuring the mode shapes of piezoelectric resonators is described. Laser speckle interference, a periodic resonator excitation and charge coupled device (CCD) image captures are effectively combined in this method. The experimental results for three kinds of AT-cut quartz resonators demonstrate the applicability of the proposed method.

Yasuaki Watanabe; Yuji Shikama; Shigeyoshi Goka; Takayuki Sato; Hitoshi Sekimoto

2001-01-01

102

Detecting spin perturbations using magnetic resonance imaging  

US Patent & Trademark Office Database

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

2012-08-21

103

Measuring nonconstant flow in magnetic resonance imaging.  

PubMed

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

Izen, S H; Haacke, E M

1990-01-01

104

Creating a magnetic resonance imaging ontology.  

PubMed

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

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

2011-01-01

105

Cardiac imaging using gated magnetic resonance  

SciTech Connect

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.

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

1984-01-01

106

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.

2009-10-29

107

Magnetic resonance imaging of atherosclerotic vascular disease.  

PubMed

Atherosclerosis is a chronic, progressive, and often widespread arterial disorder in which the morphology and composition of the arterial segments containing atheroma are of considerable importance. Magnetic resonance imaging (MRI) allows non-invasive assessment of early arterial disease without the use of ionizing radiation. Arterial compliance, flow-wave velocity, and the pattern of flow within the aorta may all be disturbed by the disease, but these parameters are all accessible to MRI. In addition, atheroma can be directly imaged. Thus, MRI is valuable not only in the detection of disease, but also in the study of its natural history and the effects of interventions such as the control of risk factors and the use of lipid-lowering agents. PMID:8297541

Underwood, R S; Mohiaddin, R H

1993-11-01

108

Clinical applications of cardiovascular magnetic resonance imaging  

PubMed Central

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

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

2006-01-01

109

Magnetic resonance imaging and safety aspects.  

PubMed

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

Coskun, Ozlem

2010-11-26

110

Magnetic resonance imaging of anterior cruciate ligament rupture  

Microsoft Academic Search

BACKGROUND: Magnetic resonance (MR) imaging is a useful diagnostic tool for the assessment of knee joint injury. Anterior cruciate ligament repair is a commonly performed orthopaedic procedure. This paper examines the concordance between MR imaging and arthroscopic findings. METHODS: Between February, 1996 and February, 1998, 48 patients who underwent magnetic resonance (MR) imaging of the knee were reported to have

Kai-Jow Tsai; Hongsen Chiang; Ching-Chuan Jiang

2004-01-01

111

Image fusion for dynamic contrast enhanced magnetic resonance imaging  

PubMed Central

Background Multivariate imaging techniques such as dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) have been shown to provide valuable information for medical diagnosis. Even though these techniques provide new information, integrating and evaluating the much wider range of information is a challenging task for the human observer. This task may be assisted with the use of image fusion algorithms. Methods In this paper, image fusion based on Kernel Principal Component Analysis (KPCA) is proposed for the first time. It is demonstrated that a priori knowledge about the data domain can be easily incorporated into the parametrisation of the KPCA, leading to task-oriented visualisations of the multivariate data. The results of the fusion process are compared with those of the well-known and established standard linear Principal Component Analysis (PCA) by means of temporal sequences of 3D MRI volumes from six patients who took part in a breast cancer screening study. Results The PCA and KPCA algorithms are able to integrate information from a sequence of MRI volumes into informative gray value or colour images. By incorporating a priori knowledge, the fusion process can be automated and optimised in order to visualise suspicious lesions with high contrast to normal tissue. Conclusion Our machine learning based image fusion approach maps the full signal space of a temporal DCE-MRI sequence to a single meaningful visualisation with good tissue/lesion contrast and thus supports the radiologist during manual image evaluation.

Twellmann, Thorsten; Saalbach, Axel; Gerstung, Olaf; Leach, Martin O; Nattkemper, Tim W

2004-01-01

112

Prospects for neutron probed magnetic resonance imaging  

SciTech Connect

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

Granroth, Garrett E [ORNL

2009-01-01

113

Small Animal Imaging with Magnetic Resonance Microscopy  

PubMed Central

Small animal magnetic resonance microscopy (MRM) has evolved significantly from testing the boundaries of imaging physics to its expanding use today as a tool in non-invasive biomedical investigations. This review is intended to capture the state-of-the-art in MRM for scientists who may be unfamiliar with this modality, but who want to apply its capabilities to their research. We therefore include a brief review of MR concepts and methods of animal handling and support before covering a range of MRM applications including the heart, lung, brain, and the emerging field of MR histology. High-resolution anatomical imaging reveals increasingly exquisite detail in healthy animals and subtle architectural aberrations that occur in genetically altered models. Resolution of 100 µm in all dimensions is now routinely attained in living animals, and 10 µm3 is feasible in fixed specimens. Such images almost rival conventional histology while allowing the object to be viewed interactively in any plane. MRM is now increasingly used to provide functional information in living animals. Images of the beating heart, breathing lung, and functioning brain can be recorded. While clinical MRI focuses on diagnosis, MRM is used to reveal fundamental biology or to non-invasively measure subtle changes in the structure or function of organs during disease progression or in response to experimental therapies. The ability of MRM to provide a detailed functional and anatomical picture in rats and mice, and to track this picture over time, makes it a promising platform with broad applications in biomedical research.

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

2009-01-01

114

Magnetic resonance imaging in glenohumeral instability  

PubMed Central

The glenohumeral joint is the most commonly dislocated joint of the body and anterior instability is the most common type of shoulder instability. Magnetic resonance (MR) imaging, and more recently, MR arthrography, have become the essential investigation modalities of glenohumeral instability, especially for pre-procedure evaluation before arthroscopic surgery. Injuries associated with glenohumeral instability are variable, and can involve the bones, the labor-ligamentous components, or the rotator cuff. Anterior instability is associated with injuries of the anterior labrum and the anterior band of the inferior glenohumeral ligament, in the form of Bankart lesion and its variants; whereas posterior instability is associated with reverse Bankart and reverse Hill-Sachs lesion. Multidirectional instability often has no labral pathology on imaging but shows specific osseous changes such as increased chondrolabral retroversion. This article reviews the relevant anatomy in brief, the MR imaging technique and the arthrographic technique, and describes the MR findings in each type of instability as well as common imaging pitfalls.

Jana, Manisha; Gamanagatti, Shivanand

2011-01-01

115

Small animal imaging with magnetic resonance microscopy.  

PubMed

Small animal magnetic resonance microscopy (MRM) has evolved significantly from testing the boundaries of imaging physics to its expanding use today as a tool in noninvasive biomedical investigations. MRM now increasingly provides functional information about living animals, with images of the beating heart, breathing lung, and functioning brain. Unlike clinical MRI, where the focus is on diagnosis, MRM is used to reveal fundamental biology or to noninvasively measure subtle changes in the structure or function of organs during disease progression or in response to experimental therapies. High-resolution anatomical imaging reveals increasingly exquisite detail in healthy animals and subtle architectural aberrations that occur in genetically altered models. Resolution of 100 mum in all dimensions is now routinely attained in living animals, and (10 mum)(3) is feasible in fixed specimens. Such images almost rival conventional histology while allowing the object to be viewed interactively in any plane. In this review we describe the state of the art in MRM for scientists who may be unfamiliar with this modality but who want to apply its capabilities to their research. We include a brief review of MR concepts and methods of animal handling and support, before covering a range of MRM applications-including the heart, lung, and brain-and the emerging field of MR histology. The ability of MRM to provide a detailed functional and anatomical picture in rats and mice, and to track this picture over time, makes it a promising platform with broad applications in biomedical research. PMID:18172332

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

2008-01-01

116

Functional magnetic resonance imaging using RASER  

PubMed Central

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

Goerke, Ute; Garwood, Michael; Ugurbil, Kamil

2010-01-01

117

Functional magnetic resonance imaging using RASER.  

PubMed

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

Goerke, Ute; Garwood, Michael; Ugurbil, Kamil

2010-08-08

118

Diffusion-weighted magnetic resonance imaging of the temporal bone  

Microsoft Academic Search

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

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

2010-01-01

119

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

Microsoft Academic Search

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

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

2006-01-01

120

Probing tissue microstructure with restriction spectrum imaging: Histological and theoretical validation.  

PubMed

Water diffusion magnetic resonance imaging (dMRI) is a powerful tool for studying biological tissue microarchitectures in vivo. Recently, there has been increased effort to develop quantitative dMRI methods to probe both length scale and orientation information in diffusion media. Diffusion spectrum imaging (DSI) is one such approach that aims to resolve such information based on the three-dimensional diffusion propagator at each voxel. However, in practice, only the orientation component of the propagator function is preserved when deriving the orientation distribution function. Here, we demonstrate how a straightforward extension of the linear spherical deconvolution (SD) model can be used to probe tissue orientation structures over a range (or "spectrum") of length scales with minimal assumptions on the underlying microarchitecture. Using high b-value Cartesian q-space data on a rat brain tissue sample, we demonstrate how this "restriction spectrum imaging" (RSI) model allows for separating the volume fraction and orientation distribution of hindered and restricted diffusion, which we argue stems primarily from diffusion in the extraneurite and intraneurite water compartment, respectively. Moreover, we demonstrate how empirical RSI estimates of the neurite orientation distribution and volume fraction capture important additional structure not afforded by traditional DSI or fixed-scale SD-like reconstructions, particularly in gray matter. We conclude that incorporating length scale information in geometric models of diffusion offers promise for advancing state-of-the-art dMRI methods beyond white matter into gray matter structures while allowing more detailed quantitative characterization of water compartmentalization and histoarchitecture of healthy and diseased tissue. PMID:23169482

White, Nathan S; Leergaard, Trygve B; D'Arceuil, Helen; Bjaalie, Jan G; Dale, Anders M

2012-01-16

121

Use of contrast agents in oncological imaging: magnetic resonance imaging.  

PubMed

Magnetic resonance plays a leading role in the management of oncology patients, providing superior contrast resolution and greater sensitivity compared with other techniques, which enables more accurate tumor identification, characterization and staging. Contrast agents are widely used in clinical magnetic resonance imaging; approximately 40-50% of clinical scans are contrast enhanced. Most contrast agents are based on the paramagnetic gadolinium ion Gd3+, which is chelated to avoid the toxic effects of free gadolinium. Multiple factors such as molecule structure, molecule concentration, dose, field strength and temperature determine the longitudinal and transverse relaxation rates (R1 and R2, respectively) and thus the T1- and T2-relaxivities of these chelates. These T1- and T2-relaxivities, together with their pharmacokinetic properties (i.e. distribution and concentration in the area of interest), determine the radiologic efficacy of the gadolinium-based contrast agents. PMID:24060901

Morana, Giovanni; Cugini, Christian; Scatto, Giuliano; Zanato, Riccardo; Fusaro, Michele; Dorigo, Alberto

2013-09-23

122

A desktop magnetic resonance imaging system.  

PubMed

Modern magnetic resonance imaging (MRI) systems consist of several complex, high cost subsystems. The cost and complexity of these systems often makes them impractical for use as routine laboratory instruments, limiting their use to hospitals and dedicated laboratories. However, advances in the consumer electronics industry have led to the widespread availability of inexpensive radio-frequency integrated circuits with exceptional abilities. We have developed a small, low-cost MR system derived from these new components. When combined with inexpensive desktop magnets, this type of MR scanner has the promise of becoming standard laboratory equipment for both research and education. This paper describes the development of a prototype desktop MR scanner utilizing a 0.21 T permanent magnet with an imaging region of approximately 2 cm diameter. The system uses commercially available components where possible and is programmed in LabVIEW software. Results from 3D data sets of resolution phantoms and fixed, newborn mice demonstrate the capability of this system to obtain useful images from a system constructed for approximately $13,500. PMID:11755094

Wright, Steven M; Brown, David G; Porter, Jay R; Spence, David C; Esparza, Emilio; Cole, David C; Huson, F Russell

2002-01-01

123

Segmentation of neuroanatomy in magnetic resonance images  

NASA Astrophysics Data System (ADS)

Segmentation in neurological magnetic resonance imaging (MRI) is necessary for feature extraction, volume measurement and for the three-dimensional display of neuroanatomy. Automated and semi-automated methods offer considerable advantages over manual methods because of their lack of subjectivity, their data reduction capabilities, and the time savings they give. We have used dual echo multi-slice spin-echo data sets which take advantage of the intrinsically multispectral nature of MRI. As a pre-processing step, a rf non-uniformity correction is applied and if the data is noisy the images are smoothed using a non-isotropic blurring method. Edge-based processing is used to identify the skin (the major outer contour) and the eyes. Edge-focusing has been used to significantly simplify edge images and thus allow simple postprocessing to pick out the brain contour in each slice of the data set. Edge- focusing is a technique which locates significant edges using a high degree of smoothing at a coarse level and tracks these edges to a fine level where the edges can be determined with high positional accuracy. Both 2-D and 3-D edge-detection methods have been compared. Once isolated, the brain is further processed to identify CSF, and, depending upon the MR pulse sequence used, the brain itself may be sub-divided into gray matter and white matter using semi-automatic contrast enhancement and clustering methods.

Simmons, Andrew; Arridge, Simon R.; Barker, G. J.; Tofts, Paul S.

1992-06-01

124

TOPICAL REVIEW: Endovascular interventional magnetic resonance imaging  

NASA Astrophysics Data System (ADS)

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

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

2003-07-01

125

Thoracic magnetic resonance imaging: pulmonary thromboembolism.  

PubMed

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

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

2013-05-01

126

Role of chelates in magnetic resonance imaging studies.  

PubMed

Imaging studies are tests performed with a variety of techniques that produce pictures of the inside of a patient's body. Magnetic resonance imaging (MRI) is an imaging technique based on the principles of nuclear magnetic resonance. MRI uses a powerful magnetic field, radio waves, and a computer to produce detailed pictures of organs, soft tissues, bone, and virtually all other internal body structures. Chelates have a wide application in such imaging techniques. Chelates in imaging studies are used alone as radioactive agents or conjugated to monoclonal antibodies or to DNA as radioactive agents. Technetium chelates and gadolinium chelates are being widely used as magnetic resonance contrast media. PMID:19841554

Tripathi, Laxmi; Kumar, Praveen; Singh, Ranjit

127

Antenna coupling circuit for magnetic resonance imaging  

SciTech Connect

A coupling circuit for coupling an inductive coil antenna of a magnetic resonance imaging system to receiver circuitry is described comprising: capacitive means, coupled in parallel with the antenna, for providing capacitive reactance in the coupling circuit; resistive means, coupled in parallel with the antenna and with the capacitive means, for providing resistance R in the coupling circuit when the inductive reactance of the coupling circuit is equal to the capacitive reactance of the coupling circuit; and capacitive transformer means, coupled between the antenna and the receiver circuitry in series with the antenna, for transforming the resistance value R of the resistive means into a transformed resistance value R', thereby increasing the apparent resistance of the coupling circuit in parallel with the antenna.

Fox, T.R.

1988-03-15

128

Magnetic Resonance Imaging in Amyotrophic Lateral Sclerosis  

PubMed Central

Amyotrophic lateral sclerosis (ALS) is a rapidly progressing neurodegenerative disorder which is incurable to date. As there are many ongoing studies with therapeutic candidates, it is of major interest to develop biomarkers not only to facilitate early diagnosis but also as a monitoring tool to predict disease progression and to enable correct randomization of patients in clinical trials. Magnetic resonance imaging (MRI) has made substantial progress over the last three decades and is a practical, noninvasive method to gain insights into the pathology of the disease. Disease-specific MRI changes therefore represent potential biomarkers for ALS. In this paper we give an overview of structural and functional MRI alterations in ALS with the focus on task-free resting-state investigations to detect cortical network failures.

Kollewe, Katja; Korner, Sonja; Dengler, Reinhard; Petri, Susanne; Mohammadi, Bahram

2012-01-01

129

Magnetic resonance imaging of palindromic rheumatism.  

PubMed

A 44-year-old man with intermittent asymmetric migratory oligoarthritis lasting the recent decade was admitted to our hospital. Considerable specific biomarkers for rheumatoid arthritis such as anti-agalactosyl IgG antibody are all negative. He was diagnosed as palindromic rheumatism (PR). Although hand X-rays showed no remarkable findings, hand magnetic resonance imaging (MRI) detected pannus and bone erosion. PR is defined as the disease characterized by short-lasting attacks of acute oligoarthritis, without radiographic changes. To our knowledge, the findings of MRI for PR have not been previously described. We propose that MRI findings in patients with PR is useful tool to distinguish PR from rheumatoid arthritis (RA) or other RA related diseases. PMID:18663450

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

2008-07-29

130

[Clinical application of functional magnetic resonance imaging].  

PubMed

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

Sugishita, Morihiro

2002-03-01

131

Functional magnetic resonance imaging in schizophrenia  

PubMed Central

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

Gur, Raquel E.; Gur, Ruben C.

2010-01-01

132

Magnetic resonance imaging of the knee.  

PubMed

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

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

133

Burn injury by nuclear magnetic resonance imaging.  

PubMed

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

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

134

Fast neutron resonance radiography for elemental imaging: theory and applications  

Microsoft Academic Search

Fast Neutron Resonance Radiography (NRR) has been devised as an elemental imaging method with applications such as contraband detection and mineral analysis. In NRR, a 2-D elemental mapping of hydrogen, carbon, nitrogen oxygen and the sum of other elements is obtained from fast neutron radiographic images taken at different neutron energies chosen to cover the resonance cross-section features of one

Gongyin Chen; Richard C. Lanza

2001-01-01

135

Magnetic Resonance Imaging System Based on Earth's Magnetic Field  

Microsoft Academic Search

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

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

2004-01-01

136

Clinical applications of magnetic resonance imaging - current status  

Microsoft Academic Search

Magnetic resonance imaging has far-reaching real and possible clinical applications. Its usefulness has been best explored and realized in the central nervous system, especially the posterior fossa and brain stem, where most abnormalities are better identified than with computed tomography. Its lack of ionizing radiation and extreme sensitivity to normal and abnormal patterns of myelination make magnetic resonance imaging advantageous

D. Cammoun; W. R. Hendee; K. A. Davis

1985-01-01

137

Simultaneous in vivo positron emission tomography and magnetic resonance imaging  

Microsoft Academic Search

Positron emission tomography (PET) and magnetic resonance imaging (MRI) are widely used in vivo imaging technologies with both clinical and biomedical research applications. The strengths of MRI include high-resolution, high-contrast morphologic imaging of soft tissues; the ability to image physiologic parameters such as diffusion and changes in oxygenation level resulting from neuronal stimulation; and the measurement of metabolites using chemical

Ciprian Catana; Daniel Procissi; Yibao Wu; Martin S. Judenhofer; Jinyi Qi; Bernd J. Pichler; Russell E. Jacobs; Simon R. Cherry

2008-01-01

138

Magnetic resonance imaging of acute Maisonneuve fractures.  

PubMed

Magnetic resonance imaging (MRI) studies were performed on five patients with acute Maisonneuve fractures. All patients had sustained a twisting injury to their ankles and complained of ankle pain and pain over their proximal fibula. High quality images with excellent visualization of all the ankle ligamentous structures were obtained. MRI showed that the anterior inferior tibiofibular ligament was disrupted in all patients and the posterior inferior tibiofibular ligament was intact in three of five patients. Also, the anterior talofibular ligament was disrupted in all patients and the calcaneofibular ligament was ruptured in two of five patients. This raises the question of whether patients with Maisonneuve fractures have lateral ankle instability at long-term follow-up. Although the superficial deltoid ligament was disrupted in all patients, the deep deltoid ligament was intact in one patient, partially disrupted in one patient, and completely disrupted in three patients. The interosseous ligament was disrupted at the ankle in all patients, while the interosseous membrane was disrupted in the leg in all patients except one. This patient had an intact interosseous membrane despite rupture of the interosseous ligament at the ankle and the presence of a proximal one third fibula fracture. PMID:8734795

Morris, J R; Lee, J; Thordarson, D; Terk, M R; Brustein, M

1996-05-01

139

Breast magnetic resonance imaging: an overview for nonradiologists.  

PubMed

Magnetic resonance imaging is a major component of breast imaging. Many studies have shown that magnetic resonance imaging is the most sensitive imaging method for detecting invasive breast cancer in comparison with mammography, ultrasound, and clinical breast examinations. Evidence-based clinical indications for breast magnetic resonance imaging include screening patients at high risk for breast cancer, including those with breast/ovarian cancer genes (BRCA1 and BRCA2), those who are untested first-degree relatives of carriers of these genes, those whose lifetime risk of developing breast cancer is 20% to 25% or greater, those who had chest radiation when they were 10 to 30 years old, and those who have or are first-degree relatives of people with Li-Fraumeni syndrome, Cowden syndrome, or Bannayan-Riley-Ruvalcaba syndrome. Breast magnetic resonance imaging is performed in conjunction with mammography and does not replace mammography. Outside of the screening population, utilization of breast magnetic resonance imaging for newly diagnosed breast cancer patients and its use as a problem-solving technique for equivocal mammographic or clinical findings remain controversial. An understanding of the current evidence facilitates appropriate utilization of this important medical resource. This article discusses indications for ordering breast magnetic resonance imaging and how to read the breast magnetic resonance imaging report and understand the lexicon used. PMID:20014426

Margolies, Laurie; Ha, Richard

2009-12-01

140

Imaging of Surfaces by Concurrent Surface Plasmon Resonance and Surface Plasmon Resonance-Enhanced Fluorescence  

PubMed Central

Surface plasmon resonance imaging and surface plasmon induced fluorescent are sensitive tools for surface analysis. However, existing instruments in this area have provided limited capability for concurrent detection, and may be large and expensive. We demonstrate a highly cost-effective system capable of concurrent surface plasmon resonance microscopy (SPRM) and surface plasmon resonance-enhanced fluorescence (SPRF) imaging, allowing for simultaneous monitoring of reflectivity and fluorescence from discrete spatial regions. The instrument allows for high performance imaging and quantitative measurements with surface plasmon resonance, and surface plasmon induced fluorescence, with inexpensive off-the-shelf components.

Thariani, Rahber; Yager, Paul

2010-01-01

141

Combined magnetic resonance imaging and spectroscopic imaging approach to molecular imaging of prostate cancer  

Microsoft Academic Search

Magnetic resonance spectroscopic imaging (MRSI) provides a noninvasive method of detecting small molecular mark- ers (historically the metabolites choline and citrate) within the cytosol and extracellular spaces of the prostate, and is performed in conjunction with high-resolution anatomic imaging. Recent studies in pre-prostatectomy patients have indicated that the metabolic information provided by MRSI combined with the anatomical information provided by

John Kurhanewicz; Mark G. Swanson; Sarah J. Nelson; Daniel B. Vigneron

2002-01-01

142

Imaging of tophaceous gout: computed tomography provides specific images compared with magnetic resonance imaging and ultrasonography  

Microsoft Academic Search

Objective: To determine the usefulness of computed tomography (CT), magnetic resonance imaging (MRI), and Doppler ultrasonography (US) in providing specific images of gouty tophi.Methods: Four male patients with chronic gout with tophi affecting the knee joints (three cases) or the olecranon processes of the elbows (one case) were assessed. Crystallographic analyses of the synovial fluid or tissue aspirates of the

J C Gerster; M Landry; L Dufresne; J Y Meuwly

2002-01-01

143

Magnetic Resonance Imaging in Postprostatectomy Radiotherapy Planning  

SciTech Connect

Purpose: To investigate whether the use of magnetic resonance imaging (MRI) in prostate bed treatment planning could influence definition of the clinical target volume (CTV) and organs at risk. Methods and Materials: A total of 21 consecutive patients referred for prostate bed radiotherapy were included in the present retrospective study. The CTV was delineated according to the European Organization for Research and Treatment of Cancer recommendations on computed tomography (CT) and T{sub 1}-weighted (T{sub 1}w) and T{sub 2}-weighted (T{sub 2}w) MRI. The CTV magnitude, agreement, and spatial differences were evaluated on the planning CT scan after registration with the MRI scans. Results: The CTV was significantly reduced on the T{sub 1}w and T{sub 2}w MRI scans (13% and 9%, respectively) compared with the CT scans. The urinary bladder was drawn smaller on the CT scans and the rectum was smaller on the MRI scans. On T{sub 1}w MRI, the rectum and urinary bladder were delineated larger than on T{sub 2}w MRI. Minimal agreement was observed between the CT and T{sub 2}w images. The main spatial differences were measured in the superior and superolateral directions in which the CTV on the MRI scans was 1.8-2.9 mm smaller. In the posterior and inferior border, no difference was seen between the CT and T{sub 1}w MRI scans. On the T{sub 2}w MRI scans, the CTV was larger in these directions (by 1.3 and 1.7 mm, respectively). Conclusions: The use of MRI in postprostatectomy radiotherapy planning resulted in a reduction of the CTV. The main differences were found in the superior part of the prostate bed. We believe T{sub 2}w MRI enables more precise definition of prostate bed CTV than conventional planning CT.

Sefrova, Jana, E-mail: sefrova@post.cz [Department of Oncology and Radiotherapy, University Hospital Hradec Kralove, Hradec Kralove (Czech Republic); Odrazka, Karel [Department of Clinical and Radiation Oncology, Multiscan and Pardubice Regional Hospital, Pardubice (Czech Republic); First and Third Faculty of Medicine, Charles University in Prague, Prague (Czech Republic); Paluska, Petr [Department of Oncology and Radiotherapy, University Hospital Hradec Kralove, Hradec Kralove (Czech Republic); Belobradek, Zdenek [Department of Radiology, University Hospital Hradec Kralove, Hradec Kralove (Czech Republic); Brodak, Milos [Department of Urology, University Hospital Hradec Kralove, Hradec Kralove (Czech Republic); Dolezel, Martin [Department of Clinical and Radiation Oncology, Multiscan and Pardubice Regional Hospital, Pardubice (Czech Republic); First and Third Faculty of Medicine, Charles University in Prague, Prague (Czech Republic); Prosvic, Petr [Department of Urology, Regional Hospital Nachod, Nachod (Czech Republic); Macingova, Zuzana; Vosmik, Milan [Department of Oncology and Radiotherapy, University Hospital Hradec Kralove, Hradec Kralove (Czech Republic); Hoffmann, Petr [Department of Radiology, University Hospital Hradec Kralove, Hradec Kralove (Czech Republic); Louda, Miroslav [Department of Urology, University Hospital Hradec Kralove, Hradec Kralove (Czech Republic); Nejedla, Anna [Department of Oncology and Radiotherapy, University Hospital Hradec Kralove, Hradec Kralove (Czech Republic)

2012-02-01

144

[Magnetic resonance contract agents and perfusion imaging].  

PubMed

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

Benderbous, S; Bonnemain, B

1996-01-01

145

Cost effectiveness of magnetic resonance imaging in the neurosciences.  

PubMed Central

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

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

1991-01-01

146

Magnetic resonance imaging for lung cancer.  

PubMed

Since the publication of the Radiologic Diagnostic Oncology Group Report in 1991, the clinical application of pulmonary magnetic resonance imaging (MRI) in patients with lung cancer has been limited. In contrast, MRI for lung cancer has undergone continuous development, and several promising techniques have been introduced to overcome the previously suggested limitations. In addition, comparative studies involving multidetector-row computed tomography and positron emission tomography or positron emission tomography/computed tomography with 2-deoxy-2-[F]fluoro-D-glucose have shown useful new clinical applications for MRI in lung cancer. Moreover, MRI can provide not only morphologic information based on various parameters such as T1 and T2 relaxation times, tissue diffusion, perfusion, etc. but also functional information; it also has a significant role in nuclear medicine studies. In this review article, we describe recent advances made in MRI with respect to lung cancer, focusing on (1) detection of solid pulmonary nodules; (2) characterization of solid pulmonary nodules; (3) TNM staging assessment using chest and whole-body MRI examinations; (4) prediction of postsurgical lung function; and (5) prediction of tumor treatment response. We believe that further basic studies, as well as studies on clinical applications of new MRI techniques, are important for improving the management of lung cancer patients. PMID:23549390

Koyama, Hisanobu; Ohno, Yoshiharu; Seki, Shinichiro; Nishio, Mizuho; Yoshikawa, Takeshi; Matsumoto, Sumiaki; Sugimura, Kazuro

2013-05-01

147

Imaging intelligence with proton magnetic resonance spectroscopy  

PubMed Central

Proton magnetic resonance spectroscopy (1H-MRS) is a technique for the assay of brain neurochemistry in vivo. N-acetylaspartate (NAA), the most prominent metabolite visible within the 1H-MRS spectrum, is found primarily within neurons. The current study was designed to further elucidate NAA–cognition relationships, particularly whether such relationships are moderated by sex, or tissue type (gray or white matter). We administered standard measures of intelligence to 63 young, healthy subjects and obtained spectroscopic imaging data within a slab of tissue superior to the lateral ventricles. We found that lower NAA within right anterior gray matter predicted better performance VIQ (F=6.83, p=.011, r2=.10), while higher NAA within the right posterior gray matter region predicted better PIQ (F=8.175, p=.006, r2=.12). These findings add to the small but growing body of literature linking brain biochemistry to intelligence in normal healthy subjects using 1H-MRSI.

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

2009-01-01

148

Magnetic resonance imaging of the kidneys  

SciTech Connect

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

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

1984-12-01

149

Low field strength magnetic resonance imaging of the neonatal brain  

PubMed Central

Background: Magnetic resonance (MR) imaging of the neonate has been restricted by the need to transport the sick baby to the large magnetic resonance scanners and often the need for sedation or anaesthesia in order to obtain good quality images. Ultrasound is the reference standard for neonatal imaging. Objective: To establish a dedicated neonatal MR system and compare the clinical usefulness of MR imaging with ultrasound imaging. Design: Prospective double blind trial. Setting: Neonatal intensive care unit, Sheffield. Main outcome measures: Imaging reports. Patients: 134 premature and term babies. Results: In 56% of infants with pathology suspected on clinical grounds, MR provided additional useful clinical information over and above that obtained with ultrasound. Conclusion: Infants can be safely imaged by dedicated low field magnetic resonance on the neonatal intensive care unit without the need for sedation at a cost equivalent to ultrasound.

Whitby, E; Paley, M; Smith, M; Sprigg, A; Woodhouse, N; Griffiths, P

2003-01-01

150

Magnetic resonance imaging: Review of imaging techniques and overview of liver imaging  

PubMed Central

Magnetic resonance imaging (MRI) of the liver is slowly transitioning from a problem solving imaging modality to a first line imaging modality for many diseases of the liver. The well established advantages of MRI over other cross sectional imaging modalities may be the basis for this transition. Technological advancements in MRI that focus on producing high quality images and fast imaging, increasing diagnostic accuracy and developing newer function-specific contrast agents are essential in ensuring that MRI succeeds as a first line imaging modality. Newer imaging techniques, such as parallel imaging, are widely utilized to shorten scanning time. Diffusion weighted echo planar imaging, an adaptation from neuroimaging, is fast becoming a routine part of the MRI liver protocol to improve lesion detection and characterization of focal liver lesions. Contrast enhanced dynamic T1 weighted imaging is crucial in complete evaluation of diseases and the merit of this dynamic imaging relies heavily on the appropriate timing of the contrast injection. Newer techniques that include fluoro-triggered contrast enhanced MRI, an adaptation from 3D MRA imaging, are utilized to achieve good bolus timing that will allow for optimum scanning. For accurate interpretation of liver diseases, good understanding of the newer imaging techniques and familiarity with typical imaging features of liver diseases are essential. In this review, MR sequences for a time efficient liver MRI protocol utilizing newer imaging techniques are discussed and an overview of imaging features of selected common focal and diffuse liver diseases are presented.

Maniam, Santhi; Szklaruk, Janio

2010-01-01

151

Narrow band deformable registration of prostate magnetic resonance imaging, magnetic resonance spectroscopic imaging, and computed tomography studies  

Microsoft Academic Search

Purpose: Endorectal (ER) coil-based magnetic resonance imaging (MRI) and magnetic resonance spectroscopic imaging (MRSI) is often used to obtain anatomic and metabolic images of the prostate and to accurately identify and assess the intraprostatic lesions. Recent advancements in high-field (3 Tesla or above) MR techniques affords significantly enhanced signal-to-noise ratio and makes it possible to obtain high-quality MRI data. In

Eduard Schreibmann; Lei Xing

2005-01-01

152

Quantifying Mixing using Magnetic Resonance Imaging  

PubMed Central

Mixing is a unit operation that combines two or more components into a homogeneous mixture. This work involves mixing two viscous liquid streams using an in-line static mixer. The mixer is a split-and-recombine design that employs shear and extensional flow to increase the interfacial contact between the components. A prototype split-and-recombine (SAR) mixer was constructed by aligning a series of thin laser-cut Poly (methyl methacrylate) (PMMA) plates held in place in a PVC pipe. Mixing in this device is illustrated in the photograph in Fig. 1. Red dye was added to a portion of the test fluid and used as the minor component being mixed into the major (undyed) component. At the inlet of the mixer, the injected layer of tracer fluid is split into two layers as it flows through the mixing section. On each subsequent mixing section, the number of horizontal layers is duplicated. Ultimately, the single stream of dye is uniformly dispersed throughout the cross section of the device. Using a non-Newtonian test fluid of 0.2% Carbopol and a doped tracer fluid of similar composition, mixing in the unit is visualized using magnetic resonance imaging (MRI). MRI is a very powerful experimental probe of molecular chemical and physical environment as well as sample structure on the length scales from microns to centimeters. This sensitivity has resulted in broad application of these techniques to characterize physical, chemical and/or biological properties of materials ranging from humans to foods to porous media 1, 2. The equipment and conditions used here are suitable for imaging liquids containing substantial amounts of NMR mobile 1H such as ordinary water and organic liquids including oils. Traditionally MRI has utilized super conducting magnets which are not suitable for industrial environments and not portable within a laboratory (Fig. 2). Recent advances in magnet technology have permitted the construction of large volume industrially compatible magnets suitable for imaging process flows. Here, MRI provides spatially resolved component concentrations at different axial locations during the mixing process. This work documents real-time mixing of highly viscous fluids via distributive mixing with an application to personal care products.

Tozzi, Emilio J.; McCarthy, Kathryn L.; Bacca, Lori A.; Hartt, William H.; McCarthy, Michael J.

2012-01-01

153

Magnetic Field Issues in Magnetic Resonance Imaging.  

NASA Astrophysics Data System (ADS)

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

Petropoulos, Labros Spiridon

154

Acquisition Times in Magnetic Resonance Imaging: Optimization in Clinical Use  

Microsoft Academic Search

Nuclear magnetic resonance imaging is a routine clinical system used for whole-body patient scanning that provides 3D images. Recent technological innovations have encouraged the use of this technology for noninvasive coronary, heart, and chest investigation or for research applications, but the image quality of this technique depends on several factors. Some parameters are linked to the apparatus designed to acquire

Gregorio Andria; Filippo Attivissimo; Giuseppe Cavone; Anna Maria Lucia Lanzolla

2009-01-01

155

Magnetic resonance imaging of the elbow. Part II: Abnormalities of the ligaments, tendons, and nerves  

Microsoft Academic Search

Part II of this comprehensive review on magnetic resonance imaging of the elbow discusses the role of magnetic resonance imaging in evaluating patients with abnormalities of the ligaments, tendons, and nerves of the elbow. Magnetic resonance imaging can yield high-quality multiplanar images which are useful in evaluating the soft tissue structures of the elbow. Magnetic resonance imaging can detect tears

Richard Kijowski; Michael Tuite; Matthew Sanford

2005-01-01

156

Magnetic resonance imaging in entomology: a critical review  

PubMed Central

Magnetic resonance imaging (MRI) enables in vivo imaging of organisms. The recent development of the magnetic resonance microscope (MRM) has enabled organisms within the size range of many insects to be imaged. Here, we introduce the principles of MRI and MRM and review their use in entomology. We show that MRM has been successfully applied in studies of parasitology, development, metabolism, biomagnetism and morphology, and the advantages and disadvantages relative to other imaging techniques are discussed. In addition, we illustrate the images that can be obtained using MRM. We conclude that although MRM has significant potential, further improvements to the technique are still desirable if it is to become a mainstream imaging technology in entomology. Abbreviation: CSI chemical shift imaging. The dependence of the resonance frequency of a nucleus on the chemical binding of the atom or molecule in which it is contained. (N)MRI (nuclear) magnetic resonance imaging MRM magnetic resonance microscopy Voxel A contraction for volume element, which is the basic unit of MR reconstruction; represented as a pixel in the display of the MR image.

Hart, A.G.; Bowtell, R.W.; Kockenberger, W.; Wenseleers, T.; Ratnieks, F.L.W.

2003-01-01

157

Transient left ventricular apical ballooning: magnetic resonance imaging evaluation.  

PubMed

The magnetic resonance imaging characteristics of transient left ventricular apical ballooning are described in this report, and the features that distinguish it from acute myocardial infarction are emphasized. PMID:15665680

Fritz, Jan; Wittstein, Ilan S; Lima, João A C; Bluemke, David A

158

Orthopaedic magnetic resonance imaging challenge: apophyseal avulsions at the pelvis.  

PubMed

Apophyseal avulsion injuries of the hip and pelvis are frequent athletic injuries in children and adolescents, most commonly associated with explosive movement or sprinting. This article details typically encountered apophyseal injuries and their appearance on magnetic resonance imaging. PMID:23015945

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

2010-05-01

159

Infantile fibrosarcoma: Magnetic resonance imaging findings in six cases  

Microsoft Academic Search

PurposeTo retrospectively review magnetic resonance (MR) imaging features in a series of six infantile fibrosarcomas to find out if MR can suggest this unusual diagnosis and to highlight the value of MR during and following treatment.

Sandra Canale; Daniel Vanel; Dominique Couanet; Catherine Patte; Caroline Caramella; Clarisse Dromain

2009-01-01

160

SQUID-Detected Magnetic Resonance Imaging in Microtesla Magnetic Fields  

Microsoft Academic Search

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

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

2004-01-01

161

The Nobel Prize in Medicine for Magnetic Resonance Imaging  

ERIC Educational Resources Information Center

|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

Fry, Charles G.

2004-01-01

162

Maximum Entropy Reconstruction Methods in Electron Paramagnetic Resonance Imaging  

Microsoft Academic Search

Electron Paramagnetic Resonance (EPR) is a spectroscopic technique that detects and characterizes molecules with unpaired electrons (i.e., free radicals). Unlike the closely related nuclear magnetic resonance (NMR) spectroscopy, EPR is still under development as an imaging modality. Athough a number of physical factors have hindered its development, EPR's potential is quite promising in a number of important application areas, including

Calvin A. Johnson; Delia Mcgarry; John A. Cook; Nallathamby Devasahayam; James B. Mitchell; Sankaran Subramanian; Murali C. Krishna

2003-01-01

163

The Nobel Prize in Medicine for Magnetic Resonance Imaging  

ERIC Educational Resources Information Center

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

Fry, Charles G.

2004-01-01

164

Superconducting magnets for whole body magnetic resonance imaging  

Microsoft Academic Search

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

M. F. Murphy

1989-01-01

165

Magnetic resonance imaging methods in developmental science: A primer  

Microsoft Academic Search

Structural and functional magnetic resonance imaging (MRI) are increasingly common research methods among investigators interested in typically and atypically developing populations. However, the effective use of these tools requires an understanding of the basis of the magnetic resonance signal, as well as some of the additional experimental complications that arise when collecting MRI data from developmental populations. This primer provides

Ruskin H. Hunt; Kathleen M. Thomas

2008-01-01

166

Functional Magnetic Resonance Imaging of Eye Dominance at 4 Tesla  

Microsoft Academic Search

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

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

2001-01-01

167

Resonant waveguide grating imager for live cell sensing  

NASA Astrophysics Data System (ADS)

We report on a resonant waveguide grating imager for high throughput screening using live cells. This imager can generate a snapshot image of all biosensors in a 384-well microtiter plate with a time resolution of ~3 s and a spatial resolution of 80 ?m. This imager is well tolerant to variability in plate configurations and cell confluency. The resonant wavelength and its shifts induced by cell responses at each pixel correlate well with cell confluency. Data filtration protocol can be used to improve assay quality for partially confluent cells.

Ferrie, Ann M.; Wu, Qi; Fang, Ye

2010-11-01

168

Cranial and spinal magnetic resonance imaging: A guide and atlas  

SciTech Connect

This atlas provides a clinical guide to interpreting cranial and spinal magnetic resonance images. The book includes coverage of the cerebrum, temporal bone, and cervical, thoracic, and lumbar spine, with more than 400 scan images depicting both normal anatomy and pathologic findings. Introductory chapters review the practical physics of magnetic resonance (MR) imaging, offer guidelines for interpreting cranial MR scans, and provide coverage of each anatomic region of the cranium and spine. For each region, scans accompanied by captions, show normal anatomic sections matched with MR images. These are followed by MR scans depicting various disease states.

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

1987-01-01

169

An electrochemical surface plasmon resonance imaging system targeting cell analysis  

NASA Astrophysics Data System (ADS)

This paper presents an electrochemical-surface plasmon resonance imaging (EC-SPRI) system, enabling the characterization of optical and electrical properties of cells, simultaneously. The developed surface plasmon resonance (SPR) imaging system was capable of imaging micro cavities with a dimension of 10 ?m × 10 ?m and differentiated glycerol solutions with a group of refractive indices (RIs). Furthermore, the EC-SPRI system was used to image A549 cells, suggesting corresponding RI and morphology changes during the cell death process. In the end, electrochemical and SPR methods were used in combination, recording oxidation peaks of A549 cells in the cyclic voltage curves and SPR response unit increase, simultaneously.

Zhang, L. L.; Chen, X.; Wei, H. T.; Li, H.; Sun, J. H.; Cai, H. Y.; Chen, J. L.; Cui, D. F.

2013-08-01

170

Fast neutron resonance radiography for elemental imaging: theory and applications  

Microsoft Academic Search

Fast neutron resonance radiography (NRR) has been devised as an elemental imaging method with applications such as contraband detection and mineral analysis. In NRR, a two-dimensional (2-D) elemental mapping of hydrogen, carbon, nitrogen, oxygen, and the sum of other elements is obtained from fast neutron radiographic images, taken at different neutron energies and chosen to cover the resonance cross-section features

Gongyin Chen; Richard C. Lanza

2002-01-01

171

SQUID-Detected Magnetic Resonance Imaging in MicroteslaFields  

Microsoft Academic Search

Magnetic resonance imaging (MRI) has developed into a powerful clinical tool for imaging the human body (1). This technique is based on nuclear magnetic resonance (NMR) of protons (2, 3) in a static magnetic field Bâ. An applied radiofrequency pulse causes the protons to precess about Bâ at their Larmor frequency νâ = (γ\\/2Ï)Bâ, where γ is the gyromagnetic ratio;

Michael Moessle; Michael Hatridge; John Clarke

2006-01-01

172

Delayed enhancement magnetic resonance imaging in nonischemic myocardial disease.  

PubMed

This review highlights the role of delayed enhancement magnetic resonance imaging for the diagnosis of patients with nonischemic myocardial disease. The authors discuss the use of delayed enhancement for differentiation between ischemic and nonischemic myocardial disease and for narrowing the differential diagnosis when nonischemic etiologies are suspected. In addition, special focus is given to the prognostic applications of delayed enhancement magnetic resonance imaging. PMID:23422782

Moraes, Gustavo L; Higgins, Charles B; Ordovas, Karen G

2013-03-01

173

Health Effects and Safety of Magnetic Resonance Imaging  

Microsoft Academic Search

Magnetic Resonance Imaging (MRI) is a rapidly advancing diagnostic imaging modality. Hazards, intrinsic to the magnetic resonance\\u000a (MR) environment, are to be understood, acknowledged and respected. MRI is safe, but if something goes wrong, it can be serious.\\u000a MRI-related accidents do happen, unfortunately in most countries they go unreported and there is no central database which\\u000a keeps track of these

Kwan-Hoong Ng; Oliver Faust; Rajendra Acharya U

174

Deep ultraviolet resonant Raman imaging of a cell  

NASA Astrophysics Data System (ADS)

We report the first demonstration of deep ultraviolet (DUV) Raman imaging of a cell. Nucleotide distributions in a HeLa cell were observed without any labeling at 257 nm excitation with resonant bands attributable to guanine and adenine. Obtained images represent DNA localization at nucleoli in the nucleus and RNA distribution in the cytoplasm. The presented technique extends the potential of Raman microscopy as a tool to selectively probe nucleic acids in a cell with high sensitivity due to resonance.

Kumamoto, Yasuaki; Taguchi, Atsushi; Smith, Nicholas Isaac; Kawata, Satoshi

2012-07-01

175

Real-Time Magnetic Resonance Imaging: Diagnostic and Interventional Applications  

Microsoft Academic Search

.   The advent of ultra-fast imaging techniques has extended the utility of magnetic resonance imaging (MRI) from a static and\\u000a purely diagnostic status to an imaging modality ideally suited for a number of therapeutic applications. These advances—along\\u000a with the recent development and refinement of miniature intravascular imaging catheters and MRI-compatible guidewires, balloon\\u000a catheters, and radiofrequency ablation catheters—have created an exciting

Albert C. Lardo

2000-01-01

176

Multimodal Magnetic Resonance Imaging for Brain Disorders: Advances and Perspectives  

Microsoft Academic Search

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

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

2008-01-01

177

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

PubMed

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

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

2012-10-01

178

Micro-magnetic resonance imaging of avian embryos  

PubMed Central

Chick embryos are useful models for probing developmental mechanisms including those involved in organogenesis. In addition to classic embryological manipulations, it is possible to test the function of molecules and genes while the embryo remains within the egg. Here we define conditions for imaging chick embryo anatomy and for visualising living quail embryos. We focus on the developing limb and describe how different tissues can be imaged using micro-magnetic resonance imaging and this information then synthesised, using a three-dimensional visualisation package, into detailed anatomy. We illustrate the potential for micro-magnetic resonance imaging to analyse phenotypic changes following chick limb manipulation. The work with the living quail embryos lays the foundations for using micro-magnetic resonance imaging as an experimental tool to follow the consequences of such manipulations over time.

Li, Xiaojing; Liu, Jia; Davey, Megan; Duce, Suzanne; Jaberi, Neema; Liu, Gang; Davidson, Gemma; Tenent, Seaneen; Mahood, Ruth; Brown, Phoebe; Cunningham, Craig; Bain, Andrew; Beattie, Kevin; McDonald, Laura; Schmidt, Katy; Towers, Matthew; Tickle, Cheryll; Chudek, Sandy

2007-01-01

179

Pancoast Tumor: The Role of Magnetic Resonance Imaging  

PubMed Central

We report imaging techniques in the definition of the therapeutic planning of a 65-year-old man with a diagnosis of Pancoast tumor. Computed Tomography has a pivotal role in the assessment of nodes involvement and distant metastasis. Magnetic Resonance allows a detailed study of locoregional extension for its high soft tissue resolution. We particularly highlight the actual importance of Magnetic Resonance Neurography, Diffusion-Weighted Imaging, and Magnetic Resonance Angiography techniques in the assessment of the superior sulcus vascular and nervous structures involvement. Their integrity has been showed in our patient with a complete surgical excision of the lesion.

Manenti, Guglielmo; Raguso, Mario; D'Onofrio, Silvia; Altobelli, Simone; Scarano, Angela Lia; Vasili, Erald; Simonetti, Giovanni

2013-01-01

180

JAMA Patient Page: Magnetic Resonance Imaging  

MedlinePLUS

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

181

Travelling wave magnetic resonance imaging at 3 T  

NASA Astrophysics Data System (ADS)

Waveguides have been successfully used to generate magnetic resonance images at 7 T with whole-body systems. The bore diameter limits the magnetic resonance signal transmitted because its specific cut-off frequency is greater than the majority of resonant frequencies in magnetic resonance imaging and spectroscopy. This restriction can be overcome by using a parallel-plate waveguide whose cut-off frequency is zero for the transverse electromagnetic modes and it can propagate any frequency. To study the potential benefits of travelling-wave excitation for whole-body imaging at 3 T, we compare numerical simulations of the principal mode propagation for a parallel-plate waveguide filled with a cylindrical phantom and two surface coils for all simulations at 1.5 T, 3 T, 4.7, 7 T, and 9.4 T. The principal mode shows very little variation of the field magnitude along the propagation direction at 3 T when compared to other higher resonant frequencies. Unlike the standard method for travelling-wave magnetic resonance imaging, a parallel-plate waveguide prototype was built and used together with a whole-body birdcage coil for signal transmission and a pair of circular coils for reception. Experimental B1 mapping was computed to investigate the feasibility of this approach and, the point spread function method was used to measure the imager performance. Human leg images were acquired to experimentally validate this approach. The numerical magnetic field and specific absorption rate of a simulated leg were computed and results are within the safety limits. The B1 mapping and point spread function results showed that it is possible to conduct travelling-wave imaging experiments with good imager performance. Human leg images were also obtained with the whole-body birdcage coil for comparison purposes. The simulated and in vivo travelling-wave results of the human leg correspond very well for the signal received. A similar image signal-to-noise ratio was observed for the travelling-wave approach and the conventional one. We have demonstrated the feasibility of travelling-wave magnetic resonance imaging at 3 T and whole-body magnetic resonance systems, using a parallel-plate waveguide with standard pulse sequences and only one coil array. This extends the use of the waveguide approach to a wider range of resonant frequencies.

Vazquez, F.; Martin, R.; Marrufo, O.; Rodriguez, A. O.

2013-08-01

182

Magnetic Resonance Imaging and Contrast Enhancement.  

National Technical Information Service (NTIS)

Chapters II through VI of this report discuss: Relaxation of Nuclear Spins; Echo Techniques; Basic Imaging Pulse Sequences; Partial Saturation Recovery; Inversion Recovery; Spin Echo; Effects of Pulse Sequence on Image Contrast; Contrast Agents; Theoretic...

C. E. Swenberg E. G. Movius

1988-01-01

183

Magnetic resonance imaging of knee injuries in children  

Microsoft Academic Search

The purpose of this study was to evaluate the significance of meniscal appearances and determine the frequency of abnormalities seen on magnetic resonance (MR) imaging in children with knee injuries. We reviewed 78 consecutive MR imaging studies of 74 children aged 5–16 years with unfused epiphyses. Menisci were evaluated using conventional grading techniques. We used ?2 to compare the frequencies

S. J. King; H. M. L. Carty; O. Brady

1996-01-01

184

Magnetic Resonance Imaging of Cruciate Ligament Injuries of the Knee  

Microsoft Academic Search

The anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) are important stabilizers of the knee. These ligaments are commonly injured in sports and motor vehicle accidents. An accurate diagnosis of cruciate ligament injuries is vital in patient care. Magnetic resonance imaging (MRI) can diagnose cruciate ligament injuries with high accuracy. The imaging diagnosis should be based on primary signs,

C. K. Kam; Daniel W. Y. Chee; Wilfred C. G. Peh

2010-01-01

185

Magnetic Resonance Imaging in Experimental Models of Brain Disorders  

Microsoft Academic Search

This review gives an overview of the application of magnetic resonance imaging (MRI) in experimental models of brain disorders. MRI is a noninvasive and versatile imaging modality that allows longitudinal and three-dimensional assessment of tissue morphology, metabolism, physiology, and function. MRI can be sensitized to proton density, T1, T2, susceptibility contrast, magnetization transfer, diffusion, perfusion, and flow. The combination of

Rick M. Dijkhuizen; Klaas Nicolay

2003-01-01

186

Magnetic Resonance Perfusion Imaging in the Study of Language  

ERIC Educational Resources Information Center

This paper provides a brief review of various uses of magnetic resonance perfusion imaging in the investigation of brain/language relationships. The reviewed studies illustrate how perfusion imaging can reveal areas of brain where dysfunction due to low blood flow is associated with specific language deficits, and where restoration of blood flow…

Hillis, Argye E.

2007-01-01

187

Magnetic resonance imaging: an alternative to autopsy in neonatal death?  

Microsoft Academic Search

Magnetic resonance imaging (MRI) represents a non-invasive alternative to full autopsy in neonatal death if parents refuse classical full autopsy. MRI offers high resolution images of the entire neonate without disrupting the integrity of the child. Neonatal malformations or pathologies that are responsible for the death of the neonate can be identified. A major disadvantage of MR-autopsy is the lack

Thierry A. G. M Huisman

2004-01-01

188

Magnetic resonance imaging of the shoulder: rationale and current applications  

Microsoft Academic Search

Because it can demonstrate a wide range of tissue contrast with excellent resolution, magnetic resonance (MR) imaging has revolutionized imaging in many areas of the musculoskeletal system and has generated excitement among those interested in the painful shoulder. Shoulder impingement syndrome and glenohumeral instability constitute the two major categories of shoulder derangements. Correct diagnosis requires the use of appropriate pulse

R. Gary Holt; Clyde A. Helms; Lynne Steinbach; Christian Neumann; Peter L. Munk; Harry K. Genant

1990-01-01

189

Architecture of baked breads depicted by a magnetic resonance imaging  

Microsoft Academic Search

The architecture of baked breads made of fresh dough and frozen dough was depicted by magnetic resonance imaging (MRI). Pieces of bread (16 mm cubic cakes) were soaked in organic solvents containing various concentrations of heavy metals (Cu2+, Co2+ and Fe3+) and images of the grain structure of the breads were obtained. Of the organic solvents tested, acetone was preferable

Nobuaki Ishida; Hiroyuki Takano; Shigehiro Naito; Seiichiro Isobe; Kunihiko Uemura; Tomoyuki Haishi; Katsumi Kose; Mika Koizumi; Hiromi Kano

2001-01-01

190

Finger Reading by Using Functional Magnetic Resonance Imaging  

Microsoft Academic Search

Some people are able to read images or words by using their fingers rather than their eyes. Such capability of finger reading has been studied since 1979. However, the mechanism of the finger-reading phenomenon is still a mystery and remains controversial. To investigate this phenomenon, we provided a preliminary observation of finger reading capability by using functional magnetic resonance imaging

Chang-Wei Wu; Kai-Hsiang Chuang

191

Magnetic Resonance Perfusion Imaging in the Study of Language  

ERIC Educational Resources Information Center

|This paper provides a brief review of various uses of magnetic resonance perfusion imaging in the investigation of brain/language relationships. The reviewed studies illustrate how perfusion imaging can reveal areas of brain where dysfunction due to low blood flow is associated with specific language deficits, and where restoration of blood flow…

Hillis, Argye E.

2007-01-01

192

Magnetic resonance imaging (MRI) and relaxation time mapping of concrete  

Microsoft Academic Search

The use of Magnetic Resonance Imaging (MRI) of water in concrete is presented. This thesis will approach the problem of MR imaging of concrete by attempting to design new methods, suited to concrete materials, rather than attempting to force the material to suit the method. A number of techniques were developed, which allow the spatial observation of water in concrete

Steven Donald Beyea

2001-01-01

193

Magnetic resonance and nuclear medicine imaging in ataxias  

Microsoft Academic Search

Imaging techniques including computed tomography (CT), magnetic resonance imaging (MRI), single photon emission computed tomography (SPECT), and positron emission tomography (PET) have been widely applied to the investigation of patients with acute or chronic ataxias. Fundamentally, CT has a role in the emergency evaluation of the patient with acute ataxia to ascertain brainstem or cerebellar hemorrhage and to exclude a

Mario Mascalchi; Alessandra Vella

2011-01-01

194

Combining magnetic resonance imaging and ultrawideband radar: A new concept for multimodal biomedical imaging  

Microsoft Academic Search

Due to the recent advances in ultrawideband (UWB) radar technologies, there has been widespread interest in the medical applications of this technology. We propose the multimodal combination of magnetic resonance (MR) and UWB radar for improved functional diagnosis and imaging. A demonstrator was established to prove the feasibility of the simultaneous acquisition of physiological events by magnetic resonance imaging and

F. Thiel; M. Hein; U. Schwarz; J. Sachs; F. Seifert

2009-01-01

195

An unusual burn during routine magnetic resonance imaging.  

PubMed

Burn injuries are known to occur from magnetic resonance imaging. Prevention efforts focus on avoiding internal and external metallic objects from contacting the patient's tissue during image acquisition. Despite rigorous screening, however, there is a subset of thermal injuries that can occur through the formation of closed loops of current within the patient. This case report describes an example of this uncommon type of injury as well as a successful, nonoperative management approach. Given the frequent use of magnetic resonance imaging, we report this rare case to raise awareness of this mechanism of injury and its treatment. PMID:23128132

Friedstat, Jonathan S; Moore, Molly E; Goverman, Jeremy; Fagan, Shawn P

196

Echo-Planar Imaging: Magnetic Resonance Imaging in a Fraction of a Second  

Microsoft Academic Search

Progress has recently been made in implementing magnetic resonance imaging (MRI) techniques that can be used to obtain images in a fraction of a second rather than in minutes. Echo-planar imaging (EPI) uses only one nuclear spin excitation per image and lends itself to a variety of critical medical and scientific applications. Among these are evaluation of cardiac function in

Michael K. Stehling; Robert Turner; Peter Mansfield

1991-01-01

197

Factors affecting perceived tumor volumes in magnetic resonance imaging  

Microsoft Academic Search

Irregularly structured brain tumors, such as glioblastomas, challenge attempts to visualize and quantify their three-dimensional\\u000a structure. Magnetic resonance imaging (MRI) represents one tool for attempting to noninvasively track tumor size. MR images\\u000a demonstrate widely varying perceived tumor margins. In addition, adjunct therapies, such as the administration of steroids,\\u000a greatly affect the volumes perceived in images formed by certain pulse sequences.

Robert L. Galloway; Robert J. Maciunas; Ann L. Failinger

1993-01-01

198

Magnetic resonance imaging of vascular changes in Takayasu arteritis  

Microsoft Academic Search

We studied the thoracic aorta in 42 female patients with Takayasu arteritis by magnetic resonance imaging (MRI) with a 1.5-T superconducting instrument and compared the findings with those in 10 healthy female controls. Images in the transaxial and oblique sagittal planes were acquired by cardiac gating using a spin-echo pulse sequence. Images in the oblique plane were also obtained with

Akihiro Hata; Fujio Numano

1995-01-01

199

Magnetic resonance imaging and histopathology of cerebral gliomas  

Microsoft Academic Search

The correlation of magnetic resonance imaging (MRI) with histopathological findings was analysed in 26 patients with untreated cerebral gliomas. In low-grade gliomas, T2-weighted images demonstrated relatively homogeneous high-intensity lesions involving both the grey and the white matter. In high-grade gliomas, especially grade IV, T2-weighted images demonstrated prominent heterogeneity in signal intensity, which consisted of a hyperintense “core”, less hyperintense or

M. Watanabe; R. Tanaka; N. Takeda

1992-01-01

200

Plasmon—resonant gold nanoparticles for cancer optical imaging  

NASA Astrophysics Data System (ADS)

Gold nanoparticles (AuNPs) interact with light and have strong and tunable surface plasmon resonance, which can be detected using multiple imaging modalities. These provide an unique opportunity for their potential applications in optical imaging for early detection of cancer. In this review, we summarized nanoparticles targeting properties for cancer, plasmon optical properties of AuNPs, application of AuNPs for cancer optical imaging. Also discussed is the safety of AuNPs.

Wang, Zhen

2013-03-01

201

Magnetic resonance imaging of brain angiogenesis after stroke  

Microsoft Academic Search

Stroke is a major cause of mortality and long-term disability worldwide. The initial changes in local perfusion and tissue\\u000a status underlying loss of brain function are increasingly investigated with noninvasive imaging methods. In addition, there\\u000a is a growing interest in imaging of processes that contribute to post-stroke recovery. In this review, we discuss the application\\u000a of magnetic resonance imaging (MRI)

Peter R. SeevinckLisette; Lisette H. Deddens; Rick M. Dijkhuizen

2010-01-01

202

Magnetic Resonance Image Tissue Classification Using a Partial Volume Model  

Microsoft Academic Search

We describe a sequence of low-level operations to isolate and classify brain tissue within T1-weighted magnetic resonance images (MRI). Our method first removes nonbrain tissue using a combination of anisotropic diffusion filtering, edge detection, and mathematical morphology. We compensate for image nonuniformities due to magnetic field inhomogeneities by fitting a tricubic B-spline gain field to local estimates of the image

David W. Shattuck; Stephanie R. Sandor-Leahy; Kirt A. Schaper; David A. Rottenberg; Richard M. Leahy

2001-01-01

203

Imaging Intelligence with Proton Magnetic Resonance Spectroscopy  

ERIC Educational Resources Information Center

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

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

2009-01-01

204

Magnetic resonance imaging in patients with panhypopituitarism  

Microsoft Academic Search

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

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

1992-01-01

205

Magnetic Resonance Imaging of Biological Specimens by Electron Paramagnetic Resonance of Nitroxide Spin Labels  

NASA Astrophysics Data System (ADS)

Electron paramagnetic resonance imaging was demonstrated on two plant species, Apium graveolens and Coleus blumei. This was accomplished by soaking stems of these plants in the paramagnetic nitroxide imaging agent 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl. The experiments were accomplished at L-band frequency (1.4 to 1.9 gigahertz) with single-turn, flat-loop surface coils. One-dimensional imaging spectra were diagnostic of capillary structure and long-term stability.

Berliner, Lawrence J.; Fujii, Hirotada

1985-02-01

206

Evaluation of Magnetic Resonance Imaging in Coarctation of the Aorta: The Importance of Multiple Imaging Planes  

Microsoft Academic Search

.   Coarctation of the aorta can be evaluated reliably and noninvasively by magnetic resonance imaging. However, the value of\\u000a different imaging planes in the evaluation of restenosis or aneurysm has not previously been studied. Our purpose was to study\\u000a the relative sensitivity for oblique coronal and oblique parasagittal magnetic resonance imaging to detect restenosis or aneurysm\\u000a formation in children following

S. B. Greenberg; L. A. Marks; E. E. Eshaghpour

1997-01-01

207

Gradient Moment Compensated Magnetic Resonance Spectroscopic Imaging  

PubMed Central

Spectroscopic imaging applications outside of the brain can suffer from artifacts due to inherent long scan times and susceptibility to motion. A fast spectroscopic imaging sequence has been devised with reduced sensitivity to motion. The sequence uses oscillating readout gradients and acquires k-space data in a spiral out–in fashion, which allows fast k-space coverage. We show that a spiral out–in readout acquisition is characterized by small gradient moments, reducing sensitivity to motion-induced artifacts. Data are acquired comparing the sequence to normal phase encoded spectroscopic imaging and conventional spiral spectroscopic imaging protocols. In addition, in vivo data are acquired from the liver, demonstrating potential usage as a multivoxel fat/water spectroscopic imaging tool. Results indicate that in the presence of motion, ghosting effects are reduced while metabolite signal increases of approximately 10% can be achieved.

Kim, Dong-Hyun; Gu, Meng; Spielman, Daniel M.

2010-01-01

208

Magnetic Resonance Imaging of the Rectum During Distension  

Microsoft Academic Search

PURPOSE  A knowledge of the relationships between the rectum and its surrounding structures during distention may improve our understanding of the results of studies assessing rectal sensory-motor responses to distention. This magnetic resonance imaging study was designed to assess the shape of the rectum and the degree of distention at which the surrounding structures are compressed.METHODS  Nine healthy patients underwent magnetic resonance

Annalisa Dal Lago; Alberto E. Minetti; Pietro Biondetti; Maura Corsetti; Guido Basilisco

2005-01-01

209

Basic Principles of Magnetic Resonance Imaging--An Update  

PubMed Central

Magnetic resonance (MR) imaging technology has undergone many technologic advances over the past few years. Many of these advances were stimulated by the wealth of information emerging from nuclear magnetic resonance research in the areas of new and optimal scanning methods and radio-frequency coil design. Other changes arose from the desire to improve image quality, ease siting restrictions and generally facilitate the clinical use of MR equipment. Many questions, however, remain unanswered. Perhaps the most controversial technologic question involves the optimal field strength required for imaging or spectroscopic applications or both. Other issues include safety and clinical efficacy. Technologic issues affect all aspects of MR use including the choice of equipment, examination procedure and image interpretation. Thus, an understanding of recent changes and their theoretic basis is necessary. ImagesFigure 9.

Scherzinger, Ann L.; Hendee, William R.

1985-01-01

210

Mediastinal masses: magnetic resonance imaging in comparison with computed tomography.  

PubMed Central

Seventy-eight patients with mediastinal abnormalities were imaged with magnetic resonance imaging (MRI) to evaluate mediastinal masses and associated lung, pleural, or chest wall disease. Magnetic resonance images were compared with computed tomography (CT) scans, which were available in 45 patients. While MRI and CT were equally effective in demonstrating mediastinal lesions, CT was superior for displaying calcification within a mass in eight patients and for demonstrating associated lung abnormality in four patients. Computed tomography should remain the imaging procedure of choice after chest radiography to evaluate mediastinal masses, although MRI may be indicated in selected patients. Images Figures 1A-B Figures 2A-D Figures 3A-C

Batra, P.; Brown, K.; Collins, J. D.; Holmes, E. C.; Steckel, R. J.; Shapiro, B. J.

1991-01-01

211

Brain magnetic resonance imaging with contrast dependent on blood oxygenation.  

PubMed Central

Paramagnetic deoxyhemoglobin in venous blood is a naturally occurring contrast agent for magnetic resonance imaging (MRI). By accentuating the effects of this agent through the use of gradient-echo techniques in high fields, we demonstrate in vivo images of brain microvasculature with image contrast reflecting the blood oxygen level. This blood oxygenation level-dependent (BOLD) contrast follows blood oxygen changes induced by anesthetics, by insulin-induced hypoglycemia, and by inhaled gas mixtures that alter metabolic demand or blood flow. The results suggest that BOLD contrast can be used to provide in vivo real-time maps of blood oxygenation in the brain under normal physiological conditions. BOLD contrast adds an additional feature to magnetic resonance imaging and complements other techniques that are attempting to provide positron emission tomography-like measurements related to regional neural activity. Images

Ogawa, S; Lee, T M; Kay, A R; Tank, D W

1990-01-01

212

Magnetic resonance imaging of tumor oxygenation and metabolic profile.  

PubMed

Abstract The tumor microenvironment is distinct from normal tissue as a result of abnormal vascular network characterized by hypoxia, low pH, high interstitial fluid pressure and elevated glycolytic activity. This poses a barrier to treatments including radiation therapy and chemotherapy. Imaging methods which can characterize such features non-invasively and repeatedly will be of significant value in planning treatment as well as monitoring response to treatment. The three techniques based on magnetic resonance imaging (MRI) are reviewed here. Tumor pO2 can be measured by two MRI methods requiring an exogenous contrast agent: electron paramagnetic resonance imaging (EPRI) and Overhauser magnetic resonance imaging (OMRI). Tumor metabolic profile can be assessed by a third method, hyperpolarized metabolic MR, based on injection of hyperpolarized biological molecules labeled with (13)C or (15)N and MR spectroscopic imaging. Imaging pO2 in tumors is now a robust pre-clinical imaging modality with potential for implementation clinically. Pre-clinical studies and an initial clinical study with hyperpolarized metabolic MR have been successful and suggest that the method may be part of image-guided radiotherapy to select patients for tailored individual treatment regimens. PMID:23957619

Krishna, Murali C; Matsumoto, Shingo; Saito, Keita; Matsuo, Masayuki; Mitchell, James B; Ardenkjaer-Larsen, Jan H

2013-08-19

213

[Diagnostic approach to cardiopathies by means of magnetic resonance imaging].  

PubMed

Cardiomyopathies encompass a broad spectrum of heart pathologies having a basic principle, the intrinsic injury of the myocardial fiber. By definition, cardiomyopathies could be primary (dilated cardiomyopathy), or can be a consequence of another cardiovascular illness (high blood pressure), or of genetic anomalies, such as hypertrophic cardiomyopathy, or due to alterations in myocytes due to fibrolipidic material as occurs in right ventricle arrhythmogenic dysplasia. Currently, magnetic resonance imaging is the best method to approach the diagnosis of these pathologies. Magnetic resonance imaging has allowed us to study histological sections through adequate sequences and using gadolinium as contrast agent. We present herein a simple way to approach the diagnosis of cardiomyopathies by means of magnetic resonance imaging methods. PMID:15909747

Gutiérrez Zamora, Agustín

214

Accurate Temperature Imaging Based on Intermolecular Coherences in Magnetic Resonance  

PubMed Central

Conventional magnetic resonance methods that provide interior temperature profiles, which find use in clinical applications such as hyperthermic therapy, can develop inaccuracies caused by the inherently inhomogeneous magnetic field within tissues or by probe dynamics, and work poorly in important applications such as fatty tissues. We present a magnetic resonance method that is suitable for imaging temperature in a wide range of environments. It uses the inherently sharp resonances of intermolecular zero-quantum coherences, in this case flipping up a water spin while flipping down a nearby fat spin. We show that this method can rapidly and accurately assign temperatures in vivo on an absolute scale.

Galiana, Gigi; Branca, Rosa T.; Jenista, Elizabeth R.; Warren, Warren S.

2010-01-01

215

Magnetic resonance imaging for evaluating neurogenic dysphagia  

Microsoft Academic Search

Dysphagia due to CNS pathology usually stems from one of two patterns of disease: (1) bilateral corticobulbar tract dysfunction\\u000a (“pseudobulbar palsy”) or (2) pontomedullary dysfunction (“bulbar palsy”). Computed tomography (CT) has proved to be useful\\u000a for evaluating the brainstem in patients with neurogenic dysphagia. Nonetheless, artifacts are common in CT imaging of the\\u000a posterior fossa. Also, direct sagittal imaging is

Won S. Kim; David Buchholz; Ashok J. Kumar; Martin W. Donner; Arthur E. Rosenbaum

1987-01-01

216

Magnetic Resonance Imaging: From Spin Physics to Medical Diagnosis  

NASA Astrophysics Data System (ADS)

Two rather similar historical evolutions are evoked, each one originating in fundamental spin studies by physicists, and ending as magnetic resonance imaging (MRI), a set of invaluable tools for clinical diagnosis in the hands of medical doctors. The first one starts with the early work on nuclear magnetic resonance, the founding stone of the usual proton-based MRI, of which the basic principles are described. The second one starts with the optical pumping developments made to study the effects of spin polarization in various fundamental problems. Its unexpected outcome is a unique imaging modality, also based on MRI, for the study of lung physiology and pathologies.

Nacher, Pierre-Jean

217

Magnetic resonance imaging findings in Axenfeld-Rieger syndrome.  

PubMed

Axenfeld-Rieger syndrome (ARS) is a genetic disorder representing a disease spectrum resulting from neural crest cell maldevelopment. Glaucoma is a common complication from the incomplete formation of the iridocorneal angle structures. Neural crest cells also form structures of the forebrain and pituitary gland, dental papillae, aortic arch walls, genitalia, and long bones; therefore, patients with ARS manifest a wide range of systemic findings. To our knowledge, detailed magnetic resonance imaging findings have not been previously reported. We report a case of a 19-month-old Indian male diagnosed with ARS with emphasis on magnetic resonance imaging findings of the globes, brain, teeth, and skull base. PMID:23723681

Whitehead, Matthew T; Choudhri, Asim F; Salim, Sarwat

2013-05-21

218

Imaging Prostate Cancer: An Update on Positron Emission Tomography and Magnetic Resonance Imaging  

Microsoft Academic Search

Prostate cancer is a common cancer in men and continues to be a major health problem. Imaging plays an essential role in the\\u000a clinical management of patients. An important goal for prostate cancer imaging is more accurate disease characterization through\\u000a the synthesis of anatomic, functional, and molecular imaging information. Developments in imaging technologies, specifically\\u000a magnetic resonance imaging (MRI) and positron

Kirsten Bouchelouche; Baris Turkbey; Peter Choyke; Jacek Capala

2010-01-01

219

Breast magnetic resonance imaging for screening high-risk women.  

PubMed

Mammography is the only imaging modality that has been validated by multiple randomized clinical trials and meta-analyses to reduce mortality from breast cancer. Although it is demonstrated to be effective in reducing mortality from breast cancer, mammography has its limitations, especially in young high-risk women with dense breasts. Other imaging modalities have been pursued as an adjunct screening modality in this population. Of these, the most widely accepted is contrast-enhanced breast magnetic resonance (MR) imaging. This article reviews current recommendations and limitations of using MR imaging of the breast to screen asymptomatic women at high risk for breast cancer. PMID:23928241

Sung, Janice S; Dershaw, D David

2013-04-10

220

Neural network diagnosis of avascular necrosis from magnetic resonance images  

NASA Astrophysics Data System (ADS)

We have explored the use of artificial neural networks to diagnose avascular necrosis (AVN) of the femoral head from magnetic resonance images. We have developed multi-layer perceptron networks, trained with conjugate gradient optimization, which diagnose AVN from single sagittal images of the femoral head with 100% accuracy on the training data and 97% accuracy on test data. These networks use only the raw image as input (with minimal preprocessing to average the images down to 32 X 32 size and to scale the input data values) and learn to extract their own features for the diagnosis decision. Various experiments with these networks are described.

Manduca, Armando; Christy, Paul S.; Ehman, Richard L.

1993-09-01

221

Transformation in mandibular imaging with sweep imaging with fourier transform magnetic resonance imaging  

PubMed Central

Objective Current imaging techniques are often sub-optimal for the detection of mandibular invasion by squamous cell carcinoma. The aim of this study was to determine the feasibility of a magnetic resonance imaging (MRI) based technique known as Sweep Imaging with Fourier Transform (SWIFT) to visualize the structural changes of intra-mandibular anatomy during invasion. Design Descriptive case study Setting Tertiary academic institution Method Two specimens from patients with oral carcinoma who underwent segmental mandibulectomy were imaged using a 9.4 Tesla Varian MRI system. The SWIFT images were correlated with histological sections. Results The SWIFT technique with in vitro specimens produced images with sufficient resolution (156–273) and contrast to allow accurate depiction of tumor invasion of cortical and medullary bone. Both specimens had histopathological evidence of mandibular invasion with tumor. A high degree of correlation was found between MR images and histopathologic findings. Conclusion SWIFT MRI offers three-dimensional assessment of cortical and medullary bone in fine detail with excellent qualitative agreement with histopathology. MR imaging with the SWIFT technique demonstrates great potential to identify mandibular invasion by oral carcinoma.

Kendi, Ayse Tuba Karagulle; Khariwala, Samir S.; Zhang, Jinjin; Idiyatullin, Djaudat S.; Corum, Curtis A.; Michaeli, Shalom; Pambuccian, Stefan E.; Garwood, Michael; Yueh, Bevan

2012-01-01

222

High resolution resonance ionization imaging detector and method  

SciTech Connect

A resonance ionization imaging device (RIID) and method for imaging objects using the RIID are provided, the RIID system including a RIID cell containing an ionizable vapor including monoisotopic atoms or molecules, the cell being positioned to intercept scattered radiation of a resonance wavelength {lambda}{sub 1} from the object which is to be detected or imaged, a laser source disposed to illuminate the RIID cell with laser radiation having a wavelength {lambda}{sub 2} or wavelengths {lambda}{sub 2}, {lambda}{sub 3} selected to ionize atoms in the cell that are in an excited state by virtue of having absorbed the scattered resonance laser radiation, and a luminescent screen at the back surface of the RIID cell which presents an image of the number and position of charged particles present in the RIID cell as a result of the ionization of the excited state atoms. The method of the invention further includes the step of initially illuminating the object to be detected or imaged with a laser having a wavelength selected such that the object will scatter laser radiation having the resonance wavelength {lambda}{sub 1}.

Winefordner, J.D.; Matveev, O.I.; Smith, B.W.

1999-12-28

223

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

PubMed

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

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

1997-07-01

224

Basic principles of magnetic resonance imaging.  

PubMed

We have come full circle from spinning quarks to 3D medical images. The bulk of MRI is now performed using slice-selective gradients, during which RF energy is applied to excite the hydrogen nuclei. By stepping a phase-encoding gradient during each TR and using a frequency-encoding gradient as the data are sampled, the 3D human object can be reduced to many individual points or voxels. By acquiring multiple slices at once, the time efficiency of imaging can be vastly improved. Many newer strategies use variations of this technique to acquire multiple lines of data during a single echo, enshrining spin warp imaging as the most important method of signal acquisition for MRI. PMID:15561528

Gibby, Wendell A

2005-01-01

225

Magnetic resonance imaging for prostate cancer clinical application  

PubMed Central

As prostate cancer is a biologically heterogeneous disease for which a variety of treatment options are available, the major objective of prostate cancer imaging is to achieve more precise disease characterization. In clinical practice, magnetic resonance imaging (MRI) is one of the imaging tools for the evaluation of prostate cancer, the fusion of MRI or dynamic contrast-enhanced MRI (DCE-MRI) with magnetic resonance spectroscopic imaging (MRSI) is improving the evaluation of cancer location, size, and extent, while providing an indication of tumor aggressiveness. This review summarizes the role of MRI in the application of prostate cancer and describes molecular MRI techniques (including MRSI and DCE-MRI) for aiding prostate cancer management.

Li, Bing; Du, Yong; Huang, Yayong; Meng, Jun; Xiao, Dongmei

2013-01-01

226

Clinical applications of magnetic resonance imaging - current status  

SciTech Connect

Magnetic resonance imaging has far-reaching real and possible clinical applications. Its usefulness has been best explored and realized in the central nervous system, especially the posterior fossa and brain stem, where most abnormalities are better identified than with computed tomography. Its lack of ionizing radiation and extreme sensitivity to normal and abnormal patterns of myelination make magnetic resonance imaging advantageous for diagnosing many neonatal and pediatric abnormalities. New, reliable cardiac gating techniques open the way for promising studies of cardiac anatomy and function. The ability to image directly in three orthogonal planes gives us new insight into staging and follow-up of pelvic tumors and other pelvic abnormalities. Exquisite soft tissue contrast, far above that attainable by other imaging modalities, has made possible the early diagnosis of traumatic ligamentous knee injury, avascular necrosis of the hip and diagnosis, treatment planning and follow-up of musculoskeletal neoplasms. 59 references, 9 figures.

Cammoun, D.; Hendee, W.R.; Davis, K.A.

1985-12-01

227

Patterned Resonance Plasmonic Microarrays for High-Performance SPR Imaging  

PubMed Central

We report a novel optical platform based on SPR generation and confinement inside a defined 3-dimensional microwell geometry that leads to background resonance-free SPR images. The array shows an exceptionally high signal-to-noise ratio (S/N>80) for imaging analysis and subnanometric thickness resolution. An angular sensitivity of 1 degree/0.01 RIU has been achieved and the signal to background ratio (S/B) improves to 20, one order of magnitude higher than best literature results. The design proves effective for probing supported lipid membrane arrays in real time with a thickness resolution of 0.24 nm and allows for imaging analysis of microfluidic circuits where resonant spots are separated by only one pixel (~ 7 ?m). The high image quality and unique chip geometry open up new avenues for array screening and biomicrofluidics using SPRi detection.

Abbas, Abdennour; Linman, Matthew J.; Cheng, Quan

2011-01-01

228

Magnetic resonance imaging of perianal fistulas.  

PubMed

Most cases of fistula-in-ano are nonspecific and result from inflammation of anal glands and crypts (cryptoglandular). The classification of cryptoglandular fistulas depends on the degree of involvement of the anal sphincter complex and determines the type of treatment. Studies have shown that preoperative MR imaging revealed important additional information compared with surgery alone and better predicts clinical outcome of patients with fistula-in-ano than initial surgical exploration. With the emergence of novel surgical treatments like MRI-guided surgery, laser, and adhesive treatments, MR imaging is a mainstay for preprocedural and intraoperative evaluation to ensure the adequacy of the procedure. PMID:16152739

Dwarkasing, Soendersing; Hussain, Shahid M; Krestin, Gabriel P

2005-08-01

229

Magnetic resonance imaging of the pediatric brain  

SciTech Connect

The atlas presents sequences of MRI sections parallel to the orbito-meatal plane in children from birth through the age of sixteen years. Each child was studied horizontally and sagitally and three-dimensional brain images were reconstructed to facilitate accurate identification of sulci and gyri. The images show crucial aspects of brain development such as the constancy of the brain stem and primitive brain from birth onward; the development of the telencephalon, characterized by deepening of sulci and growth of the cerebral cortex surface; and the different stages of white matter myelinization.

Salamon, G.; Raynaud, C.; Regis, J.; Rumeau, C.

1990-01-01

230

A variable torque motor compatible with magnetic resonance imaging.  

PubMed

High magnetic fields used in magnetic resonance imaging (MRI) do not allow the employment of conventional motors due to various incompatibility issues. This paper reports on a new motor that can operate in or near high field magnets used for MRI. The motor was designed to be operational with the MRI equipment and could be used in a rotating imaging gantry inside the magnet designed for dual modality imaging. Furthermore, it could also be used for image guided robotic interventional procedures inside a MRI system if so desired. The prototype motor was developed using magnetic resonance (MR) compatible materials, and its functionality with MR imaging was evaluated experimentally by measuring the performance of the motor and its effect on the MR image quality. Since in our application, namely, single photon emission tomography, the motor has to perform precise stepping of the gantry in small angular steps the most important parameter is the start-up torque. The experimental results showed that the motor has a start-up torque up to 1.37 Nm and rotates at 196 rpm when a constant voltage difference of 12 V is applied at a magnetic field strength of 1 T. The MR image quality was quantified by measuring the signal-to-noise of images acquired under different conditions. The results presented here indicate that the motor is MR compatible and could be used for rotating an imaging gantry or a surgical device inside the magnet. PMID:19405704

Roeck, W W; Ha, S-H; Farmaka, S; Nalcioglu, O

2009-04-01

231

Magnetic Resonance Imaging of Anatomic Defects in Fecal Incontinence  

Microsoft Academic Search

Endoanal probe technology provides high-resolution soft-tissue imaging for periluminal anal and rectal disease, most notably\\u000a in complex perirectal sepsis and in patients presenting with fecal incontinence and sphincter damage. The trend is a movement\\u000a away from direct sphincter repair toward sacral neuromodulation in external anal sphincter (EAS) injury. However, endoanal\\u000a magnetic resonance imaging (EAMRI) has shown clear accuracy in the

Jaap Stoker; Andrew P. Zbar

232

Safety and Monitoring for Cardiac Magnetic Resonance Imaging  

Microsoft Academic Search

Because of unsurpassed soft tissue resolution, lack of ionizing radiation, and multi-planar imaging capability, magnetic resonance\\u000a imaging (MRI) has become an important tool in the evaluation and treatment of cardiovascular disorders. However, an increasing\\u000a proportion of patients with cardiovascular disease have higher acuity of disease and ferromagnetic implants with potential\\u000a for interaction with the MRI environment. Familiarity with each device

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

233

The Underpinnings of the BOLD Functional Magnetic Resonance Imaging Signal  

Microsoft Academic Search

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

Nikos K. Logothetis

2003-01-01

234

Magnetic resonance imaging in pantothenate kinase-2-associated neurodegeneration  

PubMed Central

Pantothenate kinase-2-associated neurodegeneration (PKAN) is a rare autosomal recessive pediatric neurodegenerative disorder characterized by rigidity, dystonia, impaired postural reflexes, and progressive dementia. On T2-weighted magnetic resonance imaging images, marked low signal intensity is seen in the globus pallidus. This low signal intensity surrounds a central region of high signal intensity in the anteromedial globus pallidus, giving an eye-of-the-tiger appearance.

Singh, Paramdeep; Saggar, Kavita; Kaur, Maneet; Pannu, Davinder Singh

2012-01-01

235

Very low field magnetic resonance imaging with spintronic sensors  

NASA Astrophysics Data System (ADS)

A very low field magnetic resonance imaging (MRI) setup based on magnetoresistive-superconducting mixed sensors is presented. A flux transformer is used to achieve coupling between the sample to image and the mixed sensor. The novel detector was implemented in a spin echo MRI experiment, exposing the mixed sensor to RF pulses without use of any RF switch. The performance of the novel detector is given in terms of signal-to-noise ratio and is compared with classical tuned coils.

Herreros, Q.; Dyvorne, H.; Campiglio, P.; Jasmin-Lebras, G.; Demonti, A.; Pannetier-Lecoeur, M.; Fermon, C.

2013-09-01

236

Brain Tumors: Apparent Diffusion Coefficient at Magnetic Resonance Imaging  

Microsoft Academic Search

\\u000a Diffusion-weighted magnetic resonance imaging (MRI) provides information on water mobility or diffusion within tissues by\\u000a allowing visualization of the Brownian motion in those tissues. Also called diffusion-weighted imaging (DWI), this technique\\u000a involves the use of phase-defocusing and phase-refocusing gradients to evaluate the rates of microscopic water diffusion within\\u000a tissues, which allows visualization and characterization of biological tissues at a microscopic

Fumiyuki Yamasaki; Kazuhiko Sugiyama; Kaoru Kurisu

237

Gated magnetic resonance imaging of congenital cardiac malformations  

SciTech Connect

Magnetic resonance (MR) images of a variety of cardiac malformations in 19 patients aged 1 week to 33 years were obtained using pulse plethysmographic- or ECG-gated spin echo pulse sequences. Coronal, axial, and sagittal images displaying intracardiac structures with excellent spatial and contrast resolution were acquired during systole or diastole. It is concluded that MR will be a valuable noninvasive method of diagnosing congenital heart disease.

Fletcher, B.D.; Jocobstein, M.D.; Nelson, A.D.; Riemenschneider, T.A.; Alfidi, R.J.

1984-01-01

238

Multisensory functional magnetic resonance imaging: a future perspective  

Microsoft Academic Search

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

Rainer Goebel; Nienke van Atteveldt

2009-01-01

239

Nuclear magnetic resonance imaging with hyperpolarised helium-3  

Microsoft Academic Search

SummaryBackground Magnetic resonance imaging (MRI) relies on magnetisation of hydrogen nuclei (protons) of water molecules in tissue as source of the signal. This technique has been valuable for studying tissues that contain significant amounts of water, but biological settings with low proton content, notably the lungs, are difficult to image. We report use of spin-polarised helium-3 for lung MRI.Methods A

M Ebert; T Grossmann; W Heil; E. W Otten; R Surkau; M Thelen; M Leduc; P Bachert; M. V Knopp; L. R Schad

1996-01-01

240

Crystallization dynamics in model emulsions from magnetic resonance imaging  

Microsoft Academic Search

Melt crystallization of trilaurin and trimyristin was investigated in the bulk and in dispersed systems using magnetic resonance\\u000a imaging. Crystallization rates were studied as a function of time in fat\\/water (40:60) emulsions containing 0.5% tween 80\\u000a and 0.2% xanthan gum to prevent creaming. Oil weighted images were obtained to follow the dynamics of crystallization in the\\u000a bulk and in an

C. Simoneau; M. J. McCarthy; R. J. Kauten; J. B. German

1991-01-01

241

Intraoperative Low-Field Magnetic Resonance Imaging in Pediatric Neurosurgery  

Microsoft Academic Search

Background: Since the mid-1990s, the feasibility and indications of intraoperative magnetic resonance (MR) imaging have been investigated by different groups. The majority of examinations were carried out in adults. The aim of this study was to summarize our experience of over 5 years of intraoperative MR imaging in pediatric neurosurgery. Methods: For scanning, we used a 0.2-Tesla Magnetom Open, which

Christopher Nimsky; Oliver Ganslandt; Jan Gralla; Michael Buchfelder; Rudolf Fahlbusch

2003-01-01

242

Automated Analysis of Craniofacial Morphology Using Magnetic Resonance Images  

Microsoft Academic Search

Quantitative analysis of craniofacial morphology is of interest to scholars working in a wide variety of disciplines, such as anthropology, developmental biology, and medicine. T1-weighted (anatomical) magnetic resonance images (MRI) provide excellent contrast between soft tissues. Given its three-dimensional nature, MRI represents an ideal imaging modality for the analysis of craniofacial structure in living individuals. Here we describe how T1-weighted

M. Mallar Chakravarty; Rosanne Aleong; Gabriel Leonard; Michel Perron; G. Bruce Pike; Louis Richer; Suzanne Veillette; Zdenka Pausova; Tomás Paus; Tianzi Jiang

2011-01-01

243

Magnetic Resonance Imaging with Fat Suppression.  

National Technical Information Service (NTIS)

A three-dimensional projection reconstruction pulse sequence acquires two half echoes in a steady state free precession (SSFP) scan. A method for combining the two echoes to suppress either fat or water in the reconstructed image is described includes shi...

A. Lu W. F. Block

2004-01-01

244

Coronary magnetic resonance vein imaging: imaging contrast, sequence, and timing.  

PubMed

Recently, there has been increased interest in imaging the coronary vein anatomy to guide interventional cardiovascular procedures such as cardiac resynchronization therapy (CRT), a device therapy for congestive heart failure (CHF). With CRT the lateral wall of the left ventricle is electrically paced using a transvenous coronary sinus lead or surgically placed epicardial lead. Proper transvenous lead placement is facilitated by the knowledge of the coronary vein anatomy. Cardiovascular MR (CMR) has the potential to image the coronary veins. In this study we propose and test CMR techniques and protocols for imaging the coronary venous anatomy. Three aspects of design of imaging sequence were studied: magnetization preparation schemes (T(2) preparation and magnetization transfer), imaging sequences (gradient-echo (GRE) and steady-state free precession (SSFP)), and imaging time during the cardiac cycle. Numerical and in vivo studies both in healthy and CHF subjects were performed to optimize and demonstrate the utility of CMR for coronary vein imaging. Magnetization transfer was superior to T(2) preparation for contrast enhancement. Both GRE and SSFP were viable imaging sequences, although GRE provided more robust results with better contrast. Imaging during the end-systolic quiescent period was preferable as it coincided with the maximum size of the coronary veins. PMID:17969081

Nezafat, Reza; Han, Yuchi; Peters, Dana C; Herzka, Daniel A; Wylie, John V; Goddu, Beth; Kissinger, Kraig K; Yeon, Susan B; Zimetbaum, Peter J; Manning, Warren J

2007-12-01

245

Brain development in Turner syndrome: a magnetic resonance imaging study  

Microsoft Academic Search

Turner syndrome (TS) results from the absence of an X chromosome in females. This genetic condition is associated with specific cognitive deficits and variations in brain volumes. The goal of this study was to use high-resolution magnetic resonance imaging (MRI) to determine morphological variations in TS and to investigate the effects of parental origin of the X chromosome on brain

Wendy E. Brown; Shelli R. Kesler; Stephan Eliez; Ilana S. Warsofsky; Michael Haberecht; Anil Patwardhan; Judith L. Ross; E. Kirk Neely; She Min Zeng; Jerome Yankowitz; Allan L Reiss

2002-01-01

246

Functional Connectivity Magnetic Resonance Imaging Classification of Autism  

ERIC Educational Resources Information Center

|Group differences in resting state functional magnetic resonance imaging connectivity between individuals with autism and typically developing controls have been widely replicated for a small number of discrete brain regions, yet the whole-brain distribution of connectivity abnormalities in autism is not well characterized. It is also unclear…

Anderson, Jeffrey S.; Nielsen, Jared A.; Froehlich, Alyson L.; DuBray, Molly B.; Druzgal, T. Jason; Cariello, Annahir N.; Cooperrider, Jason R.; Zielinski, Brandon A.; Ravichandran, Caitlin; Fletcher, P. Thomas; Alexander, Andrew L.; Bigler, Erin D.; Lange, Nicholas; Lainhart, Janet E.

2011-01-01

247

Gender effects on odor-stimulated functional magnetic resonance imaging  

Microsoft Academic Search

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

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

1999-01-01

248

Ferromagnetic Resonance Imaging using a submicron localized spin wave mode  

Microsoft Academic Search

Ferromagnetic Resonance Force Microscopy (FMRFM) is a highly sensitive spectroscopic tool for the study of nanoscale ferromagnets. Nanoscale imaging of buried or multi-component ferromagnetic systems requires a mechanism for defining the localized volume under study. Recently, we have discovered a new approach that employs the strong, nonuniform magnetic field of the micromagnetic probe tip aligned anti-parallel to magnetization in sample

Inhee Lee; Yuri Obukhov; Gang Xiang; Adam Hauser; Fengyuan Yang; Palash Banerjee; Denis Pelekhov; P. Chris Hammel

2010-01-01

249

Magnetic resonance imaging in obstructive M?llerian anomalies  

PubMed Central

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

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

2013-01-01

250

A Scalable Framework For Segmenting Magnetic Resonance Images  

PubMed Central

A fast, accurate and fully automatic method of segmenting magnetic resonance images of the human brain is introduced. The approach scales well allowing fast segmentations of fine resolution images. The approach is based on modifications of the soft clustering algorithm, fuzzy c-means, that enable it to scale to large data sets. Two types of modifications to create incremental versions of fuzzy c-means are discussed. They are much faster when compared to fuzzy c-means for medium to extremely large data sets because they work on successive subsets of the data. They are comparable in quality to application of fuzzy c-means to all of the data. The clustering algorithms coupled with inhomogeneity correction and smoothing are used to create a framework for automatically segmenting magnetic resonance images of the human brain. The framework is applied to a set of normal human brain volumes acquired from different magnetic resonance scanners using different head coils, acquisition parameters and field strengths. Results are compared to those from two widely used magnetic resonance image segmentation programs, Statistical Parametric Mapping and the FMRIB Software Library (FSL). The results are comparable to FSL while providing significant speed-up and better scalability to larger volumes of data.

Hore, Prodip; Goldgof, Dmitry B.; Gu, Yuhua; Maudsley, Andrew A.; Darkazanli, Ammar

2009-01-01

251

DIAGNOSIS OF MECHANICAL INJURIES IN AVOCADOS BY MAGNETIC RESONANCE IMAGING  

Microsoft Academic Search

SUMMARY It was aimed at to determine the potential of magnetic resonance imaging use, as non-destructive method, to evaluate the effects of the mechanical injuries in avocados. Matures fruits were used, of 'Quintal' cultivating, and the injuries were submitted by two impacts, in opposed sides of the fruit provoked by free fall from 2.00 m. In the compression injury, they

J. Sanches; C. I. Biscegli; J. F. Durigan; M. L. Simões; W. T. L. da Silva

252

Magnetic resonance imaging in juvenile asymmetric segmental spinal muscular atrophy  

Microsoft Academic Search

Magnetic resonance imaging (MRI) of cervical spine was performed in 16 patients of juvenile asymmetric segmental spinal muscular atrophy (JASSMA) in neutral and flexed positions to look for abnormalities in the spinal cord and the surrounding structures. The study included 5 normal individuals and 5 disease-negative controls who had spinal cord atrophy due to amyotrophic lateral sclerosis. In normal and

Sunil Pradhan; Rakesh K Gupta

1997-01-01

253

NMR (Nuclear Magnetic Resonance) Imaging of Human Coronary Arteries.  

National Technical Information Service (NTIS)

Nuclear magnetic resonance imaging (MRI) is being studied as a method to detect the presence of atherosclerotic lesions in the coronary arteries of humans in a totally non-invasive manner, and to characterize the anatomic features of these lesions. For th...

L. Kaufman L. Crooks C. Higgins J. Hale

1984-01-01

254

5.4 Magnetic Resonance Imaging, Diagnostic Ultrasound  

NASA Astrophysics Data System (ADS)

This document is part of Subvolume A 'Fundamentals and Data in Radiobiology, Radiation Biophysics, Dosimetry and Medical Radiological Protection' of Volume 7 'Medical Radiological Physics' of Landolt-Börnstein - Group VIII 'Advanced Materials and Technologies'. It contains the Section '5.4 Magnetic Resonance Imaging, Diagnostic Ultrasound' of the Chapter '5 Medical Radiological Protection' with the contents:

Bernhardt, J. H.

255

Three-Dimensional Magnetic Resonance Imaging of Velopharyngeal Structures  

ERIC Educational Resources Information Center

|Purpose: To report the feasibility of using a 3-dimensional (3D) magnetic resonance imaging (MRI) protocol for examining velopharyngeal structures. Using collected 3D MRI data, the authors investigated the effect of sex on the midsagittal velopharyngeal structures and the levator veli palatini (levator) muscle configurations. Method: Ten…

Bae, Youkyung; Kuehn, David P.; Sutton, Bradley P.; Conway, Charles A.; Perry, Jamie L.

2011-01-01

256

Measuring Cerebral Blood Flow Using Magnetic Resonance Imaging Techniques  

Microsoft Academic Search

Magnetic resonance imaging techniques measuring CBF have developed rapidly in the last decade, resulting in a wide range of available methods. The most successful approaches are based either on dynamic tracking of a bolus of a paramagnetic contrast agent (dynamic susceptibility contrast) or on arterial spin labeling. This review discusses their principles, possible pitfalls, and potential for absolute quantification and

Fernando Calamante; David L. Thomas; Gaby S. Pell; Jonna Wiersma; Robert Turner

1999-01-01

257

Assessing the feasibility of bronchoplastic surgery with magnetic resonance imaging.  

PubMed

Bronchoplastic surgical techniques may allow resectional therapy for non-small cell lung carcinoma in select patients in whom preoperative pulmonary function demonstrates prohibitive risk for pneumonectomy. We report an otherwise poor candidate for pneumonectomy in whom coronal magnetic resonance imaging demonstrated the potential for distal bronchial salvage. PMID:1648893

Kesler, K A; Conces, D J; Heimansohn, D A; Mathur, P

1991-07-01

258

Magnetic Resonance Imaging Facilitates Breast Conservation for Occult Breast Cancer  

Microsoft Academic Search

Introduction: Occult primary breast cancer, i.e., isolated axillary adenocarcinoma without detectable tumor in the breast by either physical exam or mammography, represents up to 1% of operable breast cancer. Modified radical mastectomy (MRM) is generally the accepted treatment for this condition although tumor is identified in only two-thirds of mastectomy specimens. Breast magnetic resonance imaging (MRI) can identify occult breast

John A. Olson; Elizabeth A. Morris; Kimberly J. Van Zee; David C. Linehan; Patrick I. Borgen

2000-01-01

259

Human Brain Language Areas Identified by Functional Magnetic Resonance Imaging  

Microsoft Academic Search

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

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

1997-01-01

260

Applications of magnetic resonance imaging in food science  

Microsoft Academic Search

The physical and chemical changes that occur in foods during growth, harvest, processing, storage, preparation, and consumption are often very difficult to measure and quantify. Magnetic resonance imaging (MRI) is a pioneering technology, originally developed in the medical field, that is now being used in a large number of disciplines to study a wide variety of materials and processes. In

Shelly J. Schmidt; Xiuzhi Sun; J. Bruce Litchfield; Thomas M. Eads

1996-01-01

261

Facial Recognition From Volume-Rendered Magnetic Resonance Imaging Data  

Microsoft Academic Search

Three-dimensional (3-D) reconstructions of computed tomography (CT) and magnetic resonance (MR) brain imaging studies are a routine component of both clinical practice and clinical and translational research. A side effect of such reconstructions is the creation of a potentially recognizable face. The Health Insurance Portability and Accountability Act of 1996 (HIPAA) Privacy Rule requires that individually identifiable health information may

Fred W. Prior; Barry S. Brunsden; Charles Hildebolt; Tracy S. Nolan; Michael Pringle; S. Neil Vaishnavi; Linda J. Larson-Prior

2009-01-01

262

Magnetic resonance imaging of lesions of synovial origin  

Microsoft Academic Search

Three patients with histologically differing lesions of synovial origin and two with synovial cysts, one of which was a dissecting popliteal cyst, were examined by magnetic resonance imaging (MR) and computerized tomography (CT). The three histologically proven synovial lesions were synovial sarcoma, diffuse giant cell tumor of tendon sheath, and synovial chondromatosis. In two of the five patients MR provided

Murali Sundaram; Michael H. McGuire; James Fletcher; Michael K. Wolverson; Elisabeth Heiberg; John B. Shields

1986-01-01

263

Double outlet left ventricle: diagnosis with magnetic resonance imaging  

Microsoft Academic Search

A complex congenital cardiac malformation in a female patient was evaluated several times by angiocardiography and echocardiography in childhood but a definite diagnosis was not established. Segmental analysis of the heart and the great vessels by magnetic resonance imaging when the patient was 34, however, showed a double outlet left ventricle in which the aorta was situated anterior to and

S A Rebergen; G L Guit; A de Roos

1991-01-01

264

Magnetic resonance imaging mapping of brain function. Human visual cortex  

Microsoft Academic Search

Magnetic resonance imaging (MRI) studies of human brain activity are described. Task-induced changes in brain cognitive state were measured using high-speed MRI techniques sensitive to changes in cerebral blood volume (CBV), blood flow (CBF), and blood oxygenation. These techniques were used to generate the first functional MRI maps of human task activation, by using a visual stimulus paradigm. The methodology

J. W. Belliveau; K. K. Kwong; D. N. Kennedy; J. R. Baker; C. E. Stern; R. Benson; D. A. Chesler; R. M. Weisskoff; M. S. Cohen; R. B. Tootell; P. T. Fox; T. J. Brady

1992-01-01

265

Optimized radiofrequency resonators for high field NMR clinical imaging  

Microsoft Academic Search

In high field (>4 Tesla) magnetic resonance imaging (MRI) systems, a major challenge is the design of radiofrequency (RF) coils that exhibit a good signal to noise ratio, tangential magnetic field (B 1) uniformity, and low specific absorption rate (SAR) in the biological tissues. As the static magnetic field increases, the frequency of operation rises and consequently the electrical dimensions

T. S. Ibrahim; R. Lee; B. B. Baertlein; P. M. L. Robitaille

2000-01-01

266

Patient Position Detection for SAR Optimization in Magnetic Resonance Imaging  

Microsoft Academic Search

Although magnetic resonance imaging is considered to be non-invasive, there is at least one effect on the patient which has to be monitored: The heating which is generated by absorbed radio frequency (RF) power. It is described using the specific absorption rate (SAR). In order to obey legal limits for these SAR values, the scanner's duty cycle has to be

Andreas Keil; Christian Wachinger; Gerhard Brinker; Stefan Thesen; Nassir Navab

2006-01-01

267

Breast cancer measurements with magnetic resonance imaging, ultrasonography, and mammography  

Microsoft Academic Search

Summary Background: Accurate measurement of the size of breast cancers becomes more important as breast cancer therapy advances. This study reports the accuracy of magnetic resonance imaging (MRI), ultrasonography and mammography for measuring the largest breast cancer diameter in comparison to the pathology measurement.

Peter L. Davis; Melinda J. Staiger; Kathleen B. Harris; Marie A. Ganott; Jolita Klementaviciene; Kenneth S. McCarty; Hector Tobon

1996-01-01

268

Functional Connectivity Magnetic Resonance Imaging Classification of Autism  

ERIC Educational Resources Information Center

Group differences in resting state functional magnetic resonance imaging connectivity between individuals with autism and typically developing controls have been widely replicated for a small number of discrete brain regions, yet the whole-brain distribution of connectivity abnormalities in autism is not well characterized. It is also unclear…

Anderson, Jeffrey S.; Nielsen, Jared A.; Froehlich, Alyson L.; DuBray, Molly B.; Druzgal, T. Jason; Cariello, Annahir N.; Cooperrider, Jason R.; Zielinski, Brandon A.; Ravichandran, Caitlin; Fletcher, P. Thomas; Alexander, Andrew L.; Bigler, Erin D.; Lange, Nicholas; Lainhart, Janet E.

2011-01-01

269

Pulmonary artery thrombus detection by magnetic resonance imaging.  

PubMed

We report a patient in whom cardiac magnetic resonance imaging detected a clinically unsuspected pulmonary artery thromboembolus. Follow-up MRI after surgical removal of the thromboembolus showed normal pulmonary arteries. This case illustrates the potential utility of MRI in the detection and follow-up of central pulmonary artery thromboembolism. PMID:2909340

Szucs, R A; Rehr, R B; Tatum, J L

1989-01-01

270

Fat and water magnetic resonance imaging.  

PubMed

A wide variety of fat suppression and water-fat separation methods are used to suppress fat signal and improve visualization of abnormalities. This article reviews the most commonly used techniques for fat suppression and fat-water imaging including 1) chemically selective fat suppression pulses "FAT-SAT"; 2) spatial-spectral pulses (water excitation); 3) short inversion time (TI) inversion recovery (STIR) imaging; 4) chemical shift based water-fat separation methods; and finally 5) fat suppression and balanced steady-state free precession (SSFP) sequences. The basic physical background of these techniques including their specific advantages and disadvantages is given and related to clinical applications. This enables the reader to understand the reasons why some fat suppression methods work better than others in specific clinical settings. PMID:20027567

Bley, Thorsten A; Wieben, Oliver; François, Christopher J; Brittain, Jean H; Reeder, Scott B

2010-01-01

271

Magnetic resonance imaging for myocardial viability.  

PubMed

Detection of myocardial viability is an important issue that needs to be addressed when patients with dysfunctional myocardium are considered to be revascularised. The pathophysiological substrate may include myocardial hibernation, myocardial stunning, or both. The greatest benefit is in terms of myocardial function recovery and prognosis is obtained if the revascularised vascular territory contains viable myocardium. Viable myocardium can be detected with nuclear techniques (SPECT, PET), low dose dobutamine stress echocardiography and MRI. With MRI robust detection of viable myocardium can be performed with delayed enhancement (with gadolinium contrast agent), low dose dobutamine stress, and stress/rest perfusion imaging. For recovery of myocardial function there are relatively small differences between all available techniques, whereas for improvement of prognosis all techniques perform equally. Myocardial delayed enhancement imaging can also visualise micro-embolisation as a result of percutaneous coronary intervention. Furthermore, MRI delayed enhancement enables differentiation between ischaemic and non-ischaemic heart disease and can identify specific cardiomyopathies. PMID:20542816

Siebelink, Hans-Marc J; Lamb, Hildo J

2010-05-01

272

Electron Spin Resonance Imaging Utilizing Localized Microwave Magnetic Field  

NASA Astrophysics Data System (ADS)

A method for two-dimensional electron spin resonance (ESR) imaging utilizing a localized microwave field is presented with an application of the image processing technique. Microwaves are localized at the surface of a sample by placing a sample in contact with a pinholed cavity wall. A two-dimensional ESR image can be obtained by scanning the sample in contact with the cavity. Some ESR images which correspond to distribution of natural radiation damages and paramagnetic impurities in carbonate fossils of a crinoid and an ammonite are presented as applications in earth science. Resolution of a raw ESR image is restricted by the diameter of the hole (1 mm). Higher resolution of 0.2 mm is obtained by using a deconvolution algorithm and instrument function for the hole. Restored images of a test sample of DPPH and of a fossil crinoid are presented.

Furusawa, Masahiro; Ikeya, Motoji

1990-02-01

273

Breast imaging and reporting data system (BIRADS): Magnetic resonance imaging  

Microsoft Academic Search

This article reviews the technical aspects and interpretation criteria in breast MR imaging based on the first edition of breast imaging and reporting data system (BIRADS) published by the American College of Radiology (ACR) in 2003. In a second article, practical cases will be proposed for training the readers. The major aims of using this lexicon are: first to use

Anne A. Tardivon; Alexandra Athanasiou; Fabienne Thibault; Carl El Khoury

2007-01-01

274

Off-resonance saturation magnetic resonance imaging of superparamagnetic polymeric micelles.  

PubMed

An off-resonance saturation (ORS) method was used for magnetic resonance imaging of superparamagnetic polymeric micelles (SPPM). SPPM was produced by encapsulating a cluster of magnetite nanoparticles (9.9+/-0.4 nm in diameter) in poly(ethylene glycol)-b-poly(D,L-lactide) (PEG-PLA) copolymer micelles (micelle diameter: 60+/-9 nm). In ORS MRI, a selective radiofrequency (RF) pulse was applied at an off-resonance position (0-50 ppm) from the bulk water signal, and the SPPM particles were visualized by the contrast on a division image constructed from two images acquired with and without pre-saturation. Here, the effects of saturation offset frequencies, saturation durations, and RF powers on ORS contrasts were investigated as these parameters are critical for optimization of ORS MRI for in vivo imaging applications. The ability to turn "ON" and "OFF" ORS contrast of SPPM solutions permits for an accurate image subtraction and a contrast enhancement to visualize SPPM probes for in vivo imaging of cancer. PMID:19964823

Khemtong, Chalermchai; Kessinger, Chase W; Togao, Osamu; Ren, Jimin; Takahashi, Masaya; Sherry, A Dean; Gao, Jinming

2009-01-01

275

Magnetic resonance imaging of the Harderian gland in piglets.  

PubMed

The main purpose of the present study was to investigate the value and effectiveness of functional and morphological magnetic resonance imaging (MRI), in order to assess the extent of brain injury in a hypoxic-ischaemic piglet model, and further to validate that the ischaemic injury was successfully induced. In this way, we also characterized the Harderian gland. MRI was performed at 1.5 T in anaesthetized piglets (n = 10, 12-36 h of age). Magnetic resonance perfusion and diffusion imaging were performed at different time points, before, during and after the induction of hypoxia-ischaemia. The effects following bilateral clamping of the carotid arteries were also assessed by contrast-enhanced magnetic resonance angiography. Morphological assessment included T1- and T2-weighted imaging, and fat-suppressed T1-weighted imaging before and after contrast medium enhancement. Morphological MRI revealed a prominent, well-defined structure located at the eyeball. Magnetic resonance angiography reconstructed with volume rendering showed this structure to be partially enclosed by large venous sinuses. At dissection, when compared with the magnetic resonance images, the deep gland of the third eyelid, the Harderian gland, corresponded to this structure both in topography and in size. By contrast, the lacrimal gland proper presented as a small, soft and pale structure that was difficult to distinguish from the surrounding connective tissue. At histological examination, the Harderian gland consisted mainly of compact areas of tubuloacinar glands with abundant eosinophilic granules. The present MRI demonstration of the Harderian gland was an accidental finding during an investigation to assess the extent of brain injury in a hypoxic-ischaemic piglet model. The combination of MRI and histology made it possible to detect and describe the Harderian gland in pig. It has generally been studied in rodents and lower vertebrates and is reported to possess various endocrine and exocrine functions. PMID:17062026

Munkeby, Berit H; Smith, Hans-Jørgen; Winther-Larssen, Eldrid H; Bjørnerud, Atle; Bjerkås, Inge

2006-11-01

276

RAPID COMMUNICATION: Magnetic resonance imaging inside metallic vessels  

NASA Astrophysics Data System (ADS)

We introduce magnetic resonance imaging (MRI) measurements inside metallic vessels. Until now, MRI has been unusable inside metallic vessels because of eddy currents in the walls. We have solved the problem and generated high quality images by employing a magnetic field gradient monitoring method. The ability to image within metal enclosures and structures means many new samples and systems are now amenable to MRI. Most importantly this study will form the basis of new MRI-compatible metallic pressure vessels, which will permit MRI of macroscopic systems at high pressure.

Han, Hui; Balcom, Bruce J.

2010-10-01

277

Interactions between magnetic resonance imaging and dental material  

PubMed Central

Magnetic resonance imaging (MRI) has become a common and important life-saving diagnostic tool in recent times, for diseases of the head and neck region. Dentists should be aware of the interactions of various restorative dental materials and different technical factors put to use by an MRI scanning machine. Specific knowledge about these impacts, at the dentist level and at the level of the personnel at the MRI centers can save valuable time for the patient and prevent errors in MRI images. Artifacts from metal restorations are a major hindrance at such times, as they result in disappearance or distortion of the image and loss of important information.

Mathew, Chalakuzhiyl Abraham; Maller, Sudhakara; Maheshwaran

2013-01-01

278

Fractal dimension of cerebral surfaces using magnetic resonance images  

SciTech Connect

The calculation of the fractal dimension of the surface bounded by the grey matter in the normal human brain using axial, sagittal, and coronal cross-sectional magnetic resonance (MR) images is presented. The fractal dimension in this case is a measure of the convolutedness of this cerebral surface. It is proposed that the fractal dimension, a feature that may be extracted from MR images, may potentially be used for image analysis, quantitative tissue characterization, and as a feature to monitor and identify cerebral abnormalities and developmental changes.

Majumdar, S.; Prasad, R.R.

1988-11-01

279

Magnetic resonance imaging for image-guided implantology  

NASA Astrophysics Data System (ADS)

Image guided implantology using navigation systems is more accurate than manual dental implant insertion. The underlying image data are usually derived from computer tomography. The suitability of MR imaging for dental implant planning is a marginal issue so far. MRI data from cadaver heads were acquired using various MRI sequences. The data were assessed for the quality of anatomical imaging, geometric accuracy and susceptibility to dental metal artefacts. For dental implant planning, 3D models of the jaws were created. A software system for segmentation of the mandible and maxilla MRI data was implemented using c++, mitk, and qt. With the VIBE_15 sequence, image data with high geometric accuracy were acquired. Dental metal artefacts were lower than in CT data of the same heads. The segmentation of the jaws was feasible, in contrast to the segmentation of the dentition, since there is a lack of contrast to the intraoral soft tissue structures. MRI is a suitable method for imaging of the region of mouth and jaws. The geometric accuracy is excellent and the susceptibility to artefacts is low. However, there are yet two limitations: Firstly, the imaging of the dentition needs further improvement to allow accurate segmentation of these regions. Secondly, the sequence used in this study takes several minutes and hence is susceptible to motion artefacts.

Eggers, Georg; Kress, Bodo; Fiebach, Jochen; Rieker, Marcus; Spitzenberg, Doreen; Marmulla, Rüdiger; Dickhaus, Hartmut; Mühling, Joachim

2006-03-01

280

Magnetic resonance imaging of musculoskeletal neoplasms.  

PubMed

MRI has been shown to be very useful in the work-up of musculoskeletal neoplasms. The lack of ionizing radiation, the superb contrast resolution, and the ability to directly scan the sagittal and coronal planes make MRI a very attractive imaging mode for treatment planning. With spin-echo MRI, maximum contrast between tumor and fatty tissues generally occurs with short TR and TE times (T1-weighted images). Likewise, maximum contrast between tumor and muscle, tendon, or ligaments occurs with long values of TR and TE (T2-weighted images). Early experience suggests that the already exceptional contrast resolution seen with MRI can be improved even more with the administration of intravenous contrast agents. Just as with CT, fatty tumors can usually be easily distinguished from other tissue types with MRI by means of their differential intensity behavior at different pulse sequences. Fluid-filled tumors, such as unicameral bone cysts or aneurysmal bone cysts may be suspected in the same manner, especially if a fluid-fluid level is seen within the lesion. Otherwise, MRI has not been useful so far in noninvasively determining the histologic type of tumors. Our experience and that of others suggests that MRI is equal or superior to CT in the work-up of musculoskeletal neoplasms. This is especially striking when it is remembered that one is comparing an immature MRI technology with a mature CT technology. Although CT presently has a central role in the staging of musculoskeletal tumors, MRI will shortly supplant it in many cases. PMID:3715000

Richardson, M L; Kilcoyne, R F; Gillespy, T; Helms, C A; Genant, H K

1986-06-01

281

Morphological evaluation of atrioventricular septal defects by magnetic resonance imaging.  

PubMed Central

Twelve patients aged between 2 weeks and 22 months (median 6 weeks) with atrioventricular septal defects were examined with a 1.5 T, whole body, magnetic resonance imaging system. Ten patients had a common atrioventricular orifice (complete defect) while two patients had separate right and left valve orifices (partial defect). Associated cardiac malformations included the tetralogy of Fallot in two, isomerism of the right atrial appendages and pulmonary atresia in two, and right isomerism and double outlet right ventricle in one. All had previously been examined by cross sectional echocardiography. Eight subsequently had angiography and six underwent surgical correction. There was one operative death and three other deaths. Three of these patients underwent postmortem examinations. Small children and infants were scanned inside a 32 cm diameter head coil. Multiple electrocardiographically gated sections 5 mm thick, separated by 0.5 mm, were acquired using a spin echo sequence with echo time of 30 ms. A combination of standard and oblique imaging planes was used. Magnetic resonance imaging was more accurate than echocardiography in predicting the size of the ventricular component of the defect. It was also better than either echocardiography and angiography in identifying the presence of ventricular hypoplasia. All these findings were confirmed by surgical or postmortem examinations or both. Magnetic resonance imaging is capable of providing detailed morphological information in children with atrioventricular septal defects which is likely to be of value in their management. Images

Parsons, J M; Baker, E J; Anderson, R H; Ladusans, E J; Hayes, A; Qureshi, S A; Deverall, P B; Fagg, N; Cook, A; Maisey, M N

1990-01-01

282

Magnetic resonance imaging of nasopharyngeal carcinoma.  

PubMed

Nasopharyngeal carcinoma (NPC) is a malignant tumor that its the highest rates in Southeast Asia. It is a locally aggressive neoplasm that has a propensity for developing regional neck adenopathy. The main treatment modality consists primarily of radiation therapy. Cross-sectional imaging is important in order to achieve an accurate delineation of tumor extent, thereby facilitating both staging and treatment. MRI is currently considered the best modality to assess for NPC. The aim of this review is to provide a pictorial MRI review of NPC according to the recently released 7th edition of the International Union Against Cancer staging system. PMID:20214518

Yu, Eugene; O'Sullivan, Brian; Kim, John; Siu, Lillian; Bartlett, Eric

2010-03-01

283

Precision and accuracy in diffusion tensor magnetic resonance imaging.  

PubMed

This article reviews some of the key factors influencing the accuracy and precision of quantitative metrics derived from diffusion magnetic resonance imaging data. It focuses on the study pipeline beginning at the choice of imaging protocol, through preprocessing and model fitting up to the point of extracting quantitative estimates for subsequent analysis. The aim was to provide the newcomers to the field with sufficient knowledge of how their decisions at each stage along this process might impact on precision and accuracy, to design their study/approach, and to use diffusion tensor magnetic resonance imaging in the clinic. More specifically, emphasis is placed on improving accuracy and precision. I illustrate how careful choices along the way can substantially affect the sample size needed to make an inference from the data. PMID:21613874

Jones, Derek K

2010-04-01

284

Magnetic resonance imaging of the central nervous system  

SciTech Connect

This report reviews the current applications of magnetic resonance imaging of the central nervous system. Since its introduction into the clinical environment in the early 1980's, this technology has had a major impact on the practice of neurology. It has proved to be superior to computed tomography for imaging many diseases of the brain and spine. In some instances it has clearly replaced computed tomography. It is likely that it will replace myelography for the assessment of cervicomedullary junction and spinal regions. The magnetic field strengths currently used appear to be entirely safe for clinical application in neurology except in patients with cardiac pacemakers or vascular metallic clips. Some shortcomings of magnetic resonance imaging include its expense, the time required for scanning, and poor visualization of cortical bone.

Not Available

1988-02-26

285

Pulsatile flow artifacts in 3D magnetic resonance imaging.  

PubMed

Some of the important features of how pulsatile flow generates artifacts in three-dimensional magnetic resonance imaging are analyzed and demonstrated. Time variations in the magnetic resonance signal during the heart cycle lead to more complex patterns of artifacts in 3D imaging than in 2D imaging. The appearance and location of these artifacts within the image volume are shown to be describable as displacements along a line in a plane parallel to that defined by the phase and volume encode directions. The angle of the line in the plane depends solely upon the imaging parameters while the ghost displacement along the line is proportional to the signal modulation frequency. Aliasing of these ghosts leads to a variety of artifact patterns which are sensitive to the pulsation period and repetition time of the pulse sequence. Numerical simulations of these effects were found to be in good agreement with experimental images of an elastic model of a human carotid artery under simulated physiological conditions and with images of two human subjects. PMID:8412600

Frank, L R; Buxton, R B; Kerber, C W

1993-09-01

286

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

ERIC Educational Resources Information Center

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

Seedhouse, Steven J.; Hoffmann, Markus M.

2008-01-01

287

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

ERIC Educational Resources Information Center

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

Seedhouse, Steven J.; Hoffmann, Markus M.

2008-01-01

288

Functional magnetic resonance imaging: measuring versus estimating.  

PubMed

Brain imaging techniques largely spread in neuroscience literature. Due to initial technical limitations such as the very low signal-to-noise ratio, group experiments became the rule. This fact, together with the wide use of standard brains to localize the activations, lead several experimenters to the wrong idea that the brain can be described by a Cartesian coordinate system, neglecting at the same time the importance of individual neuroanatomy. My commentary on the paper by Devlin and Poldrack reinforces their reminder that it is necessary to deal with anatomy. Moreover, it adds some considerations on the relevance of single subjects studies and on the importance of the BOLD intensity signal, which should be used to describe brain activity together with the most used statistical tools. PMID:17428686

Fadiga, Luciano

2007-03-06

289

Magnetic Resonance Imaging in patients with ICDs and Pacemakers  

PubMed Central

Magnetic resonance (MR) imaging has unparalleled soft-tissue imaging capabilities. The presence of devices such as pacemakers and implantable cardioverter/defibrillators (ICDs), however, is historically considered a contraindication to MR imaging. These devices are now smaller, with less magnetic material and improved electromagnetic interference protection. This review summarizes the potential hazards of the device-MR environment interaction, and presents updated information regarding in-vivo and in-vitro experiments. Recent reports on patients with implantable pacemakers and ICDs who underwent MR scan shows that under certain conditions patients with these implanted systems may benefit from this imaging modality. The data presented suggests that certain modern pacemaker and ICD systems may indeed be MR safe. This may have major clinical implications on current imaging practice.

Nair, Prashant; Roguin, Ariel

2005-01-01

290

[Magnetic resonance tomography and hybrid imaging in rheumatology].  

PubMed

In rheumatologic diseases magnet resonance imaging (MRI) is capable of depicting early inflammatory changes which are frequently missed by other imaging modalities. New MRI protocols and hardware, primarily whole-body MRI and low-field extremity MRI facilitate the use of MRI in rheumatology patients. The increasing number of functional MRI techniques provide additional molecular information on the tissue composition, e.g. cartilage quality. These molecular MRI techniques enable new ways for early disease detection and therapy monitoring. Hybrid imaging modalities, such as MRI-SPECT (single photon mmission tomography) and MRI-PET (positron emission tomography) provide a new level of molecular imaging in rheumatology by adding the advantages of the combined modalities. This article provides an up-to-date overview of new MRI techniques and innovative hybrid imaging modalities and summarizes the first available results of these procedures in rheumatologic applications. PMID:23446460

Buchbender, C; Schneider, M; Ostendorf, B

2013-03-01

291

Superconducting magnets for whole body magnetic resonance imaging  

SciTech Connect

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

Murphy, M.F.

1989-03-01

292

Cardiac motion tracking using CINE harmonic phase (HARP) magnetic resonance imaging  

Microsoft Academic Search

This article introduces a new image processing technique for rapid analysis of tagged cardiac magnetic resonance image sequences. The method uses isolated spectral peaks in SPAMM- tagged magnetic resonance images, which contain information about cardiac motion. The inverse Fourier transform of a spectral peak is a complex image whose calculated angle is called a harmonic phase (HARP) image. It is

Nael F. Osman; William S. Kerwin; Elliot R. McVeigh; Jerry L. Prince

1999-01-01

293

A Comparison Between Clinical Assessment and Magnetic Resonance Imaging of Acute Hamstring Injuries  

Microsoft Academic Search

Background: Physicians evaluating hamstring strains in professional football players are increasingly turning to magnetic resonance imaging to support the clinical diagnosis and management of the injury. However, little information is available to assess how magnetic resonance imaging compares with the clinical evaluation in establishing the duration of rehabilitation required.Hypothesis: Magnetic resonance imaging of hamstring strains can be useful in determining

Michal E. Schneider-Kolsky; Jan Lucas Hoving; Price Warren; David A. Connell

2006-01-01

294

Cellular Magnetic Resonance Imaging: In Vivo Imaging of Melanoma Cells in Lymph Nodes of Mice1  

Microsoft Academic Search

Metastasis is responsible for most deaths due to malignant melanoma. The clinical significance of micrometas- tases in the lymph is a hotly debated topic, but an improved understanding of the lymphatic spread of cancer remains important for improving cancer survival. Cellular magnetic resonance imaging (MRI) is a newly emerging field of imaging research that is expected to have a large

Paula J. Foster; Elizabeth A. Dunn; Kristina E. Karl; Jonatan A. Snir; Colleen M. Nycz; Alfred J. Harvey; Ron J. Pettis

2008-01-01

295

Detection of Light Images by Simple Tissues as Visualized by Photosensitized Magnetic Resonance Imaging  

Microsoft Academic Search

In this study, we show how light can be absorbed by the body of a living rat due to an injected pigment circulating in the blood stream. This process is then physiologically translated in the tissue into a chemical signature that can be perceived as an image by magnetic resonance imaging (MRI). We previously reported that illumination of an injected

Catherine Tempel-Brami; Iddo Pinkas; Avigdor Scherz; Yoram Salomon; Timothy Secomb

2007-01-01

296

Evaluation of sub-microsecond recovery resonators for in vivo electron paramagnetic resonance imaging.  

PubMed

Time-domain (TD) electron paramagnetic resonance (EPR) imaging at 300MHz for in vivo applications requires resonators with recovery times less than 1 micros after pulsed excitation to reliably capture the rapidly decaying free induction decay (FID). In this study, we tested the suitability of the Litz foil coil resonator (LCR), commonly used in MRI, for in vivo EPR/EPRI applications in the TD mode and compared with parallel coil resonator (PCR). In TD mode, the sensitivity of LCR was lower than that of the PCR. However, in continuous wave (CW) mode, the LCR showed better sensitivity. The RF homogeneity was similar in both the resonators. The axis of the RF magnetic field is transverse to the cylindrical axis of the LCR, making the resonator and the magnet co-axial. Therefore, the loading of animals, and placing of the anesthesia nose cone and temperature monitors was more convenient in the LCR compared to the PCR whose axis is perpendicular to the magnet axis. PMID:18042414

Hyodo, F; Subramanian, S; Devasahayam, N; Murugesan, R; Matsumoto, K; Mitchell, J B; Krishna, M C

2007-11-07

297

Resonant imaging of carotenoid pigments in the human retina  

NASA Astrophysics Data System (ADS)

We have generated high spatial resolution images showing the distribution of carotenoid macular pigments in the human retina using Raman spectroscopy. A low level of macular pigments is associated with an increased risk of developing age-related macular degeneration, a leading cause of irreversible blindness. Using excised human eyecups and resonant excitation of the pigment molecules with narrow bandwidth blue light from a mercury arc lamp, we record Raman images originating from the carbon-carbon double bond stretch vibrations of lutein and zeaxanthin, the carotenoids comprising human macular pigments. Our Raman images reveal significant differences among subjects, both in regard to absolute levels as well as spatial distribution within the macula. Since the light levels used to obtain these images are well below established safety limits, this technique holds promise for developing a rapid screening diagnostic in large populations at risk for vision loss from age-related macular degeneration.

Gellermann, Werner; Emakov, Igor V.; McClane, Robert W.

2002-06-01

298

Biosensing and imaging based on bioluminescence resonance energy transfer.  

PubMed

Bioluminescence resonance energy transfer (BRET) operates with biochemical energy generated by bioluminescent proteins to excite fluorophores and offers additional advantages over fluorescence energy transfer (FRET) for in vivo imaging and biosensing. While fluorescent proteins are frequently used as BRET acceptors, both small molecule dyes and nanoparticles can also serve as acceptor fluorophores. Semiconductor fluorescent nanocrystals or quantum dots (QDs) are particularly well suited for use as BRET acceptors due to their high quantum yields, large Stokes shifts and long wavelength emission. This review examines the potential of QDs for BRET-based bioassays and imaging, and highlights examples of QD-BRET for biosensing and imaging applications. Future development of new BRET acceptors should further expand the multiplexing capability of BRET and improve its applicability and sensitivity for in vivo imaging applications. PMID:19216068

Xia, Zuyong; Rao, Jianghong

2009-02-11

299

Magnetic resonance imaging findings of spinal intramedullary spirocercosis.  

PubMed

Spirocerca lupi is a nematode infecting dogs in tropical and subtropical areas. Aberrant S. lupi migration to different body organs, including the spinal cord, has been documented. To date, the diagnosis of aberrant spinal cord migration was made at post-mortem examination or as an incidental finding, during spinal surgery. We describe two dogs with acute asymmetric paraparesis that were subsequently diagnosed with spinal cord spirocercosis. In magnetic resonance (MR) images of the spine, T2 hyperintense lesions were seen in the spinal cord of both dogs. The lesions appeared isointense on T1-weighted images and focal enhancement was detected after gadolinium administration. The MR imaging findings were compatible with focal inflammation, presumably along the parasite migration tract. Gross and microscopic pathologic findings confirmed the diagnosis of aberrant spinal intramedullary migration of S. lupi in one dog, and in the other dog, the clinical and imaging findings were supportive of this diagnosis. PMID:18833954

Chai, Orit; Shelef, Ilan; Brenner, Ori; Dogadkin, Osnat; Aroch, Itamar; Shamir, Merav H

300

MRI (Magnetic Resonance Imaging) : tour an MRI machine  

NSDL National Science Digital Library

In this resource, appropriate for students in high school and beyond, the user navigates through a five-page illustrated explanation of MRI (magnetic resonance imaging). Each page profiles a different step in the MRI process. The resource addresses the science behind how MRI works, revealing how a strong magnet and radio wave pulses affect the targeted area of the body and allow that area to be imaged. As part of a set of materials about brain scanning technologies, this resource focuses on brain MRI. Copyright 2005 Eisenhower National Clearinghouse

Productions, David G.; York, Thirteen/wnet N.

2001-01-01

301

Magnetic resonance imaging of gel-cast ceramic composites  

SciTech Connect

Magnetic resonance imaging (MRI) techniques are being employed to aid in the development of advanced near-net-shape gel-cast ceramic composites. MRI is a unique nondestructive evaluation tool that provides information on both the chemical and physical properties of materials. In this effort, MRI imaging was performed to monitor the drying of porous green-state alumina - methacrylamide-N.N`-methylene bisacrylamide (MAM-MBAM) polymerized composite specimens. Studies were performed on several specimens as a function of humidity and time. The mass and shrinkage of the specimens were also monitored and correlated with the water content.

Dieckman, S.L.; Balss, K.M.; Waterfield, L.G. [and others

1997-04-01

302

Normal and variant abdominal anatomy on magnetic resonance imaging.  

PubMed

The diagnostic usefulness of abdominal magnetic resonance (MR) imaging lies in the improved contrast resolution and ability to qualify several tissue characteristics of a specific organ or lesion. Our institution uses organ-specific protocols to facilitate technical reproducibility and optimize scan duration. These protocols are discussed individually in this article when applicable, noting that many build on a basic protocol with slight variations. Because most abdominal MR imaging studies are targeted toward an organ or area of interest, this article discusses the protocol strategies and relevant anatomy in a segmented/organ-specific manner. PMID:21816329

Wasnik, Ashish P; Mazza, Michael B; Lalchandani, Usha R; Liu, Peter S

2011-08-01

303

Bayesian Segmentation of Magnetic Resonance Images Using the ? Stable Distribution  

Microsoft Academic Search

\\u000a In this work, a segmentation method of Magnetic Resonance images (MRI) is presented. On the one hand, the distribution of\\u000a the grey (GM) and white matter (WM) are modelled using a mixture of ?-stable distributions. A Bayesian ?-stable mixture model for histogram data is used and the unknown parameters are sampled using the Metropolis-Hastings algorithm,\\u000a therefore, voxel intensity information is

Diego Salas-Gonzalez; Matthias Schlögl; Juan Górriz; Javier Ramírez; Elmar Lang

304

Magnetic Resonance Imaging and Pituitary Function in Children with Panhypopituitarism  

Microsoft Academic Search

Background: To explore the relationship between magnetic resonance imaging (MRI) findings and multiple pituitary-target hormones in patients with panhypopituitarism or multiple pituitary hormone deficiency (MPHD). Methods: 125 patients with MPHD (102 boys, MPHD group) and 90 age-, sex- and Tanner stage-matched normal children (control group) were enrolled. 96 of the patients with MPHD underwent MRI scans of the hypothalamic-pituitary area.

Guimei Li; Peng Shao; Xiaojun Sun; Qian Wang; Lijuan Zhang

2010-01-01

305

Effects of magnetic resonance imaging on cardiac pacemakers and electrodes  

Microsoft Academic Search

In phantom studies we investigated the effects of magnetic resonance imaging (MRI) on pacemakers and electrodes. Twenty-five electrodes were exposed to MRI in a 1.5T scanner with continuous registration of the temperature at the electrode tip. Eleven pacemakers (five single chamber and six dual chamber) were exposed to MRI. Pacemaker output was monitored to detect malfunction in VOO\\/DOO and VVI\\/DDD

Stephan Achenbach; Werner Moshage; Björn Diem; Tobias Bieberle; Volker Schibgilla; Kurt Bachmann

1997-01-01

306

Subungual keratoacanthoma: ultrasound and magnetic resonance imaging findings  

Microsoft Academic Search

Subungual keratoacanthoma is a rare, squamoproliferative neoplasm arising at the nail bed. It may cause erosion of the underlying\\u000a bone. We report a case of subungual keratoacanthoma of the right thumb in a 63-year-old man. Radiographs showed cortical erosion\\u000a of the distal phalanx of the right thumb. Ultrasonography showed a mixed echoic tumor. On magnetic resonance imaging (MRI),\\u000a the tumor

Joon Hyuk Choi; Dong Hoon Shin; Duk Seop Shin; Kil Ho Cho

2007-01-01

307

Transcranial magnetic stimulation assisted by neuronavigation of magnetic resonance images  

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

308

Multifunctional magnetic nanoparticles for magnetic resonance imaging and cancer therapy  

Microsoft Academic Search

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

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

2011-01-01

309

Magnetic resonance imaging in the evaluation of congestive cardiac failure  

PubMed Central

Congestive cardiac failure is the end-result of various cardiac disorders, and is a major contributor to morbidity, mortality, and financial burden throughout the world. Due to advances in the knowledge of the disease and scanner technology, magnetic resonance imaging (MRI) is playing an increasingly important role in the evaluation of cardiac failure, including in establishing diagnosis, problem solving, risk stratification, and monitoring of therapy. This review discusses and illustrates the role of MRI in the assessment of congestive cardiac failure.

Rajiah, Prabhakar

2012-01-01

310

Thalamus Segmentation from Diffusion Tensor Magnetic Resonance Imaging  

Microsoft Academic Search

In this paper, we propose a semi-automatic thalamus and thalamus nuclei segmentation algorithm from diffusion tensor magnetic resonance imaging (DT-MRI) based on the mean-shift algorithm. Comparing with existing thalamus segmentation algorithms which are mainly based on K-means algorithm, our mean-shift based algorithm is more flexible and adaptive. It does not assume a Gaussian distribution or a fixed number of clusters.

Ye Duan; Greg Heckenberg; Yongjian Xi; Dayang Hao

2006-01-01

311

Decoding brain states using functional magnetic resonance imaging  

Microsoft Academic Search

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

Dongha Lee; Changwon Jang; Hae-Jeong Park

2011-01-01

312

Intraoperative Magnetic Resonance Imaging in the Surgical Treatment of Epilepsy  

Microsoft Academic Search

Epilepsy is the only chronic neurodegenerative disorder that can be cured with surgery. Epilepsy surgery consists of both\\u000a curative and palliative procedures. Curative surgeries are based on the removal of a focal area of the brain from which the\\u000a epilepsy arises. Often, this region can be visualized on magnetic resonance imaging (MRI) but is not apparent macroscopically\\u000a in the operating

Theodore H. Schwartz

313

3He spin exchange cells for magnetic resonance imaging  

Microsoft Academic Search

We present a protocol for the consistent fabrication of glass cells to provide hyperpolarized (HP) 3He for pulmonary magnetic resonance imaging. The method for producing HP 3He is spin-exchange optical pumping. The valved cells must hold of order 1 atm?L of gas at up to 15 atm pressure. Because characteristic spin-exchange times are several hours, the longitudinal nuclear relaxation time

R. E. Jacob; S. W. Morgan; B. Saam

2002-01-01

314

3He spin exchange cells for magnetic resonance imaging  

Microsoft Academic Search

We present a protocol for the consistent fabrication of glass cells to provide hyperpolarized (HP) 3He for pulmonary magnetic resonance imaging. The method for producing HP 3He is spin-exchange optical pumping. The valved cells must hold of order 1 atm[middle dot]L of gas at up to 15 atm pressure. Because characteristic spin-exchange times are several hours, the longitudinal nuclear relaxation

R. E. Jacob; S. W. Morgan; B. Saam

2002-01-01

315

Organic radical contrast agents for magnetic resonance imaging.  

PubMed

We report a molecular design that provides an intravenously injectable organic radical contrast agent (ORCA) for which the molecular (1)H water relaxivity (r(1)) is ca. 5 mM(-1) s(-1). The ORCA is based on spirocyclohexyl nitroxide radicals and poly(ethylene glycol) chains conjugated to a fourth-generation polypropylenimine dendrimer scaffold. The metal-free ORCA has a long shelf life and provides selectively enhanced magnetic resonance imaging in mice for over 1 h. PMID:22974177

Rajca, Andrzej; Wang, Ying; Boska, Michael; Paletta, Joseph T; Olankitwanit, Arnon; Swanson, Michael A; Mitchell, Deborah G; Eaton, Sandra S; Eaton, Gareth R; Rajca, Suchada

2012-09-17

316

Magnetic resonance imaging and computerized tomography in malignant external otitis  

Microsoft Academic Search

In malignant external otitis (MEO), determining the anatomic extent of disease and evaluating the physiologic response to therapy remain a problem. Magnetic resonance imaging (MRI) has recently become available in limited clinical settings. Four patients with MEO were evaluated using MRI, computerized tomography (CT), technetium-99 (Tc-99) bone scanning, and gallium-67 citrate (Ga-67 citrate) scanning. MRI is superior to CT, Tc-99

STUART G. GHERINI; DERALD E. BRACKMANN; WILLIAM G. BRADLEY

1986-01-01

317

Functional magnetic resonance imaging in renal artery stenosis  

Microsoft Academic Search

Renal artery stenosis (RAS) is the leading cause of secondary hypertension. Magnetic resonance (MR) imaging and in particular\\u000a MR angiography have evolved into important diagnostic tools for the detection and grading of RAS due to the lack of ionizing\\u000a radiation and nephrotoxic contrast agent. This review describes state-of-the-art MR angiographic techniques and introduces\\u000a the reader to current concepts of RAS

S. O. Schoenberg; J. R. Rieger; H. J. Michaely; H. Rupprecht; W. Samtleben; M. F. Reiser

2006-01-01

318

Improved Model-Based Magnetic Resonance Spectroscopic Imaging  

Microsoft Academic Search

Model-based techniques have the potential to reduce the artifacts and improve resolution in magnetic resonance spec- troscopic imaging, without sacrificing the signal-to-noise ratio. However, the current approaches have a few drawbacks that limit their performance in practical applications. Specifically, the clas- sicalschemesuselessflexibleimagemodelsthatleadtomodelmisfit, thusresultinginartifacts.Moreover,theperformanceofthecurrent approaches is negatively affected by the magnetic field inhomo- geneity and spatial mismatch between the anatomical references

Mathews Jacob; Xiaoping Zhu; Andreas Ebel; Norbert Schuff; Zhi-pei Liang

2007-01-01

319

Magnetic resonance imaging in the assessment of coronary artery disease  

Microsoft Academic Search

Magnetic resonance imaging (MRI) is gaining importance in cardiology as the noninvasive test of choice for patients with a\\u000a multitude of cardiovascular problems. Recently, cardiovascular MRI has emerged as an important noninvasive diagnostic modality\\u000a in the assessment of coronary artery disease. Because of its superior spatial resolution, integration of qualitative and quantitative\\u000a methodology, and excellent reproducibility, MRI has advantages over

Tarang Ray; Robert W. Biederman; Mark Doyle; Sunil Mankad

2005-01-01

320

Exploiting Temporal Information in Functional Magnetic Resonance Imaging Brain Data  

Microsoft Academic Search

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

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

2005-01-01

321

Magnetic Resonance Imaging of Benign Cardiac Masses: A Pictorial Essay  

PubMed Central

The differential diagnosis for a cardiac mass includes primary and metastatic neoplasms. While primary cardiac tumors are rare, metastatic disease to the heart is a common finding in cancer patients. Several “tumor-like” processes can mimic a true cardiac neoplasm with accurate diagnosis critical at guiding appropriate management. We present a pictorial essay of the most common benign cardiac masses and “mass-like” lesions with an emphasis on magnetic resonance imaging features.

Ward, Thomas J.; Kadoch, Michael A.; Jacobi, Adam H.; Lopez, Pablo P.; Salvo, Javier Sanz; Cham, Matthew D.

2013-01-01

322

Magnetic resonance imaging of benign cardiac masses: a pictorial essay.  

PubMed

The differential diagnosis for a cardiac mass includes primary and metastatic neoplasms. While primary cardiac tumors are rare, metastatic disease to the heart is a common finding in cancer patients. Several "tumor-like" processes can mimic a true cardiac neoplasm with accurate diagnosis critical at guiding appropriate management. We present a pictorial essay of the most common benign cardiac masses and "mass-like" lesions with an emphasis on magnetic resonance imaging features. PMID:24083071

Ward, Thomas J; Kadoch, Michael A; Jacobi, Adam H; Lopez, Pablo P; Salvo, Javier Sanz; Cham, Matthew D

2013-08-31

323

Magnetic resonance imaging of the peripheral nervous system  

Microsoft Academic Search

The diagnostic work up of patients with peripheral neuropathy largely depends on clinical and electrophysiological investigations.\\u000a In contrast to disorders of the CNS, magnetic resonance imaging (MRI) has not been widely used as a diagnostic tool in the\\u000a PNS except for detection of nerve compressing mass lesions. Normal nerves appear isointense to the surrounding tissue on T1-\\u000a and T2-weighted (w)

Guido Stoll; Martin Bendszus; Jose Perez; Mirko Pham

2009-01-01

324

Molecular magnetic resonance imaging with targeted contrast agents  

Microsoft Academic Search

Magnetic resonance imaging (MRI) produces high-resolution three-dimensional maps delineating morphological features of the specimen. Differential contrast in soft tissues depends on endogenous differences in water content, relaxation times, and\\/or diffusion characteristics of the tissue of interest. The specificity of MRI can be further increasedbyexogenouscontrastagents(CA)suchasgadoliniumchelates,whichhavebeensuccessfullyusedforimaging of hemodynamic parameters including blood perfusion and vascular permeability. Development of targeted MR CA directed to

Dmitri Artemov

2003-01-01

325

Magnetic resonance imaging of viral particle biodistribution in vivo  

Microsoft Academic Search

We describe here a technique for the visualization of viral vector delivery by magnetic resonance imaging (MRI) in vivo. By conjugating avidin-coated baculoviral vectors (Baavi) with biotinylated ultra-small superparamagnetic iron oxide particles (USPIO), we are able to produce vector-related MRI contrast in the choroid plexus cells of rat brain in vivo over a period of 14 days. Ten microlitres of

J K Räty; T Liimatainen; T Wirth; K J Airenne; T O Ihalainen; T Huhtala; E Hamerlynck; M Vihinen-Ranta; A Närvänen; S Ylä-Herttuala; J M Hakumäki

2006-01-01

326

Dynamic molecular imaging using nanoparticle plasmon resonance coupling  

NASA Astrophysics Data System (ADS)

Distance dependant coupling of plasmon resonances between closely spaced metal nanoparticles offers an attractive alternative for the imaging of molecular interactions. Here we analyzed interactions between molecular specific gold nanoparticles and live cells using a combination of dark-field reflectance and hyperspectral imaging. The results of optical imaging were correlated with transmittance electron microscopy of cell slices and theoretical simulations of optical properties of gold aggregates. We showed that nanoparticles targeted to epidermal growth factor receptor (EGFR) form closely spaced assemblies in the presence of the target molecule. Our experiments with living cells showed that receptor mediated assembly and plasmon coupling of gold bioconjugates result in a spectral shift of more than 100 nm in plasmon resonance frequency of the nanoparticles giving a very bright red signal. We demonstrated that plasmon coupling can be used for imaging of EGFR activation and trafficking as formation of EGFR dimers and further intracellular uptake in early and late endosomes is associated with progressive color changes from green to red, respectively, with each stage of EGFR cycle being associated with a distinct color of EGFR bound nanoparticles. This approach can allow imaging of molecular interactions ranging from protein pairs to multi-protein complexes with sensitivity and SNR that cannot be currently achieved with any other method.

Sokolov, K.; Aaron, J.; Larson, T.; Travis, K.; Harrison, N.

2010-02-01

327

The Nobel Prize in Medicine for Magnetic Resonance Imaging  

NASA Astrophysics Data System (ADS)

A review is given of the crucial work performed by Paul C. Lauterbur and Peter Mansfield that lead to their being awarded the Nobel Prize in Medicine in 2003. Lauterbur first expounded the idea of mapping spatial information from spectral data in nuclear magnetic resonance (NMR) through the application of magnetic field gradients (P. C. Lauterbur, Nature 1973 , 242, 190-191). One year later Mansfield and co-workers introduced the idea of selective excitation to NMR imaging (A. N. Garroway, P. K. Grannell, and P. Mansfield. J. Phys. C: Solid State Physics 1974 , 7, L457-L462). A major step in making the technique useful for clinical imaging came with Mansfield's publication of the method known as echo planar imaging (P. Mansfield, J. Phys. C: Solid State Physics 1977, 10 (3) , L55-L58). Lauterbur's and Mansfield's work captured the essence of scientific discovery, collaboration, and concerted effort to overcome significant technical issues, and were key to the development of the technique of magnetic resonance imaging (MRI). Examples of how MRI technology can be extended to chemical research are given, and limitations of the technique in this regard are discussed. Discussion of how to use commonly available NMR spectrometers for chemical imaging is also provided.

Fry, Charles G.

2004-07-01

328

Sparse magnetic resonance imaging reconstruction using the bregman iteration  

NASA Astrophysics Data System (ADS)

Magnetic resonance imaging (MRI) reconstruction needs many samples that are sequentially sampled by using phase encoding gradients in a MRI system. It is directly connected to the scan time for the MRI system and takes a long time. Therefore, many researchers have studied ways to reduce the scan time, especially, compressed sensing (CS), which is used for sparse images and reconstruction for fewer sampling datasets when the k-space is not fully sampled. Recently, an iterative technique based on the bregman method was developed for denoising. The bregman iteration method improves on total variation (TV) regularization by gradually recovering the fine-scale structures that are usually lost in TV regularization. In this study, we studied sparse sampling image reconstruction using the bregman iteration for a low-field MRI system to improve its temporal resolution and to validate its usefulness. The image was obtained with a 0.32 T MRI scanner (Magfinder II, SCIMEDIX, Korea) with a phantom and an in-vivo human brain in a head coil. We applied random k-space sampling, and we determined the sampling ratios by using half the fully sampled k-space. The bregman iteration was used to generate the final images based on the reduced data. We also calculated the root-mean-square-error (RMSE) values from error images that were obtained using various numbers of bregman iterations. Our reconstructed images using the bregman iteration for sparse sampling images showed good results compared with the original images. Moreover, the RMSE values showed that the sparse reconstructed phantom and the human images converged to the original images. We confirmed the feasibility of sparse sampling image reconstruction methods using the bregman iteration with a low-field MRI system and obtained good results. Although our results used half the sampling ratio, this method will be helpful in increasing the temporal resolution at low-field MRI systems.

Lee, Dong-Hoon; Hong, Cheol-Pyo; Lee, Man-Woo

2013-01-01

329

Cardiac magnetic resonance imaging at 3.0 T.  

PubMed

Cardiovascular magnetic resonance imaging (MRI) has gained widespread acceptance for the assessment of cardiovascular disease. Cardiac MRI requires fast data acquisition schemes because of constraints imposed by physiological motion of cardiac structures and blood flow, which dictate the suitable window of data acquisition. The ongoing improvement of MRI hardware and the development of tailored imaging techniques have been the cornerstones for rapid progress in cardiac MRI. Cardiac MRI at 3.0 T holds the promise to overcome some of the signal-to-noise (SNR) limitations, especially for techniques with borderline SNR at 1.5 T (eg, myocardial perfusion, assessment of viability, or imaging of coronary arteries). The improved SNR at 3.0 T can be used to increase the spatial resolution and/or reduce imaging time. It was shown that all applications of cardiac imaging at 1.5 T seem feasible also at 3.0 T and predominantly provide similar or improved image quality. Although specific absorption rate limitations and susceptibility effects remain a primary concern, the combination of high-field strength examinations with parallel imaging has increased the performance of techniques such as steady-state free-precession at 3.0 T. Therefore, the signal-to-noise and the contrast-to-noise ratios advantages at 3.0 T and the resulting potential benefit for an improved diagnostic value will constantly fuel further developments in this area and pave the way for novel, promising imaging techniques. PMID:17621223

Fenchel, Michael; Kramer, Ulrich; Nael, Kambiz; Miller, Stephan

2007-04-01

330

Determining Bone Bruises of the Knee with Magnetic Resonance Imaging  

PubMed Central

Introduction Injuries that develop secondary to minor traumas and cannot be detected via direct examination methods, but are detected via advanced imaging methods, such as magnetic resonance (MR) imaging, are called occult bone injuries or bone bruises. In such injuries, diagnostic arthroscopy usually does not reveal any pathology. MR imaging methods are quite beneficial for the diagnosis of such clinical conditions, which cause acute pain and restriction of motion. The present study aimed to assess occult bone injuries via MR imaging in patients who presented with minor knee trauma. Patients and Methods Twelve patients who presented with minor knee trauma were included in the study. Etiological factors in these patients included walking a long distance, falls, and minor trauma. All patients underwent physical examinations, direct radiological imaging, MR imaging, and diagnostic arthroscopy. Results Direct radiographs of the patients showed no pathological fracture. Bone marrow changes detected on the MR images were classified according to Lynch’s classification as Type I lesions in nine patients and Type II lesions in three patients. Conclusion We suggest that MR imaging methods should be the gold standard for the diagnosis of minor traumatic bruise injuries of the knee.

Ucar, Bekir Yavuz; Necmioglu, Serdar; Bulut, Mehmet; Azboy, Ibrahim; Demirtas, Abdullah; Gumus, Hatice

2012-01-01

331

Ferromagnetic resonance imaging of Co films using magnetic resonance force microscopy  

SciTech Connect

Magnetic resonance force microscope (MRFM) technique has been applied to the study of spatial imaging in thin Co ferromagnetic film. A novel approach is proposesd to improve spatial resolution in MRFM, which is limited by the broad width of Co ferromagnetic resonance (FMR) line. The authors introduce a selective local field with a small yittrium iron garnet (YIG) grain. They have performed MRFM detected FMR on a sample consisting of two sections of Co films laterally separated by {approximately}20 {micro}m. The experimental results demonstrate the scanning imaging capabilities of MRFM. The results can be understood qualitatively by means of the calculated magnetic field and field gradient profiles generated by the YIG shere.

Suh, B.J.; Hammel, P.C.; Zhang, Z. [Los Alamos National Lab., NM (United States); Midzor, M.M.; Roukes, M.L. [California Inst. of Tech., Pasadena, CA (United States); Childress, J.R. [Univ. of Florida, Gainsville, FL (United States)

1998-07-01

332

Practical magnetic resonance imaging evaluation of peripheral nerves in children: magnetic resonance neurography.  

PubMed

Magnetic resonance (MR) imaging is an excellent tool for the evaluation of peripheral nerves in children not only because of its excellent soft tissue contrast resolution but also because it is noninvasive and does not use ionizing radiation. In nonconclusive cases, MR neurography can be complementary to physical examination and electromyography in identifying a specific affected nerve and the site of the lesion. This article reviews the MR imaging technique used in the evaluation of peripheral nerves (ie, MR neurography), its major indications, and the common pathologic conditions encountered in the pediatric population. PMID:23830792

Cortes, Cesar; Ramos, Yanerys; Restrepo, Ricardo; Restrepo, Jose Andres; Grossman, John A I; Lee, Edward Y

2013-07-01

333

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

PubMed Central

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

Sharma, Rakesh; Sharma, Avdhesh

2004-01-01

334

Spatially variable Rician noise in magnetic resonance imaging.  

PubMed

Magnetic resonance images tend to be influenced by various random factors usually referred to as "noise". The principal sources of noise and related artefacts can be divided into two types: arising from hardware (acquisition coil arrays, gradient coils, field inhomogeneity); and arising from the subject (physiological noise including body motion, cardiac pulsation or respiratory motion). These factors negatively affect the resolution and reproducibility of the images. Therefore, a proper noise treatment is important for improving the performance of clinical and research investigations. Noise reduction becomes especially critical for the images with a low signal-to-noise ratio, such as those typically acquired in diffusion tensor imaging at high diffusion weightings. The standard methods of signal correction usually assume a uniform distribution of the standard deviation of the noise across the image and evaluate a single correction parameter for the whole image. We pursue a more advanced approach based on the assumption of an inhomogeneous distribution of noise in space and evaluate correction factors for each voxel individually. The Rician nature of the underlying noise is considered for low and high signal-to-noise ratios. The approach developed here has been examined using numerical simulations and in vivo brain diffusion tensor imaging experiments. The efficacy and usefulness of this approach is demonstrated here and the resultant effective tool is described. PMID:22209560

Maximov, Ivan I; Farrher, Ezequiel; Grinberg, Farida; Shah, N Jon

2011-12-10

335

Linear constraint minimum variance beamformer functional magnetic resonance inverse imaging  

PubMed Central

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

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

2011-01-01

336

Magnetic resonance imaging of canine mast cell tumors.  

PubMed

Mast cell tumors (MCT) are the most common cutaneous tumors in dogs. Our purpose was to describe the magnetic resonance (MR) imaging characteristics of cutaneous MCT and to identify imaging characteristics that allow differentiation of metastatic from normal lymph nodes. Eight dogs with a total of nineMCT were imaged as were their presumed draining and associated contralateral lymph nodes. The signal intensity of tumors and lymph nodes was compared to adjacent musculature. On T2-W images, 7/9 MCT were hyperintense to muscle and 2/9 were isointense. On T1-W images, 8/9 MCT were isointense and 1/9 were mildly hypointense. All tumors were strongly contrast enhancing; 5/9 were homogeneous and 4/9 heterogeneous in their enhancement patterns. Six lymph node pairs were included in the evaluation (five sentinel lymph nodes with metastases, one without, and six contralateral lymph nodes). Metastatic lymph nodes were significantly larger than their contralateral lymph nodes (P = 0.039). All lymph nodes were isointense on T1-W images and hyperintense on T2-W images. 5/5 metastatic and 2/7 normal lymph nodes were heterogeneously T2-hyperintense. All lymph nodes were moderately to strongly contrast enhancing. 4/5 metastatic and 2/7 normal lymph nodes had heterogeneous enhancement patterns. While heterogeneity was more common in metastatic than in normal lymph nodes, this difference was not significant (P = 0.058 for T2-W images; P = 0.234 for postcontrast images). MR imaging may be useful in the presurgical evaluation and clinical staging of cutaneous MCT. PMID:22136427

Pokorny, Esteban; Hecht, Silke; Sura, Patricia A; LeBlanc, Amy K; Phillips, Jeffrey; Conklin, Gordon A; Haifley, Katherine A; Newkirk, Kim

337

Magnetic resonance imaging findings of equine solar penetration wounds.  

PubMed

The magnetic resonance (MR) imaging features, signalment, clinical history and outcome of 55 horses with a penetrating sole injury were evaluated. Our aim was to describe MR imaging findings within the hoof capsule, assess the utility of the technique and give recommendations for the optimal MR imaging protocol to evaluate such injuries. Data from five equine hospitals were analyzed retrospectively. The tract was more likely to be visualized in animals scanned within the first week postinjury. There was no significant predisposition based on breed, age, or gender. T2*W transverse sequences were the most useful for assessment of solar penetrations due to their orientation perpendicular to the deep digital flexor tendon, the reduced scanning time, and the T2* capability of enhancing magnetic susceptibility caused by hemorrhage. PMID:21831243

del Junco, Carolina I Urraca; Mair, Tim S; Powell, Sarah E; Milner, Peter I; Font, Alex F; Schwarz, Tobias; Weaver, Martin P

338

Bias Correction for Magnetic Resonance Images via Joint Entropy Regularization.  

PubMed

Due to the imperfections of the radio frequency (RF) coil or object-dependent electrodynamic interactions, magnetic resonance (MR) images often suffer from a smooth and biologically meaningless bias field, which causes severe troubles for subsequent processing and quantitative analysis. To effectively restore the original signal, this paper simultaneously exploits the spatial and gradient features of the corrupted MR images for bias correction via the joint entropy regularization. With both isotropic and anisotropic total variation (TV) considered, two nonparametric bias correction algorithms have been proposed, namely IsoTVBiasC and AniTVBiasC. These two methods have been applied to simulated images under various noise levels and bias field corruption and also tested on real MR data. The test results show that the proposed two methods can effectively remove the bias field and also present comparable performance compared to the state-of-the-art methods. PMID:24092098

Wang, Shanshan; Xia, Yong; Dong, Pei; Luo, Jianhua; Huang, Qiu; Feng, Dagan; Li, Yuanxiang

2013-01-01

339

New developments in magnetic resonance imaging of the nail unit.  

PubMed

The evolution of dedicated magnetic resonance imaging (MRI) musculoskeletal equipment allows new sequences and better images of the nail unit. The use of MRI has modified the imaging strategies used in treating inflammatory arthritis. In the case of psoriatic arthritis (PsA), the MRI study of the nail unit identifies nail involvement, which appears as an initial lesion for the induction of distal phalanx damage and consequently of distal interphalangeal joint arthritis. All patients with psoriasis, even in the absence of a clinically evident onychopathy, show characteristic MRI changes in the nail. This evidence could have a practical diagnostic value, because MRI study of the nail could document diagnosis in patients with undifferentiated spondyloarthropathies who have a barely evident psoriasis. We discuss the advantages and problems related to the use of low-field and high-field MRI in the study of the nail unit of patients with PsA. PMID:22751592

Soscia, Ernesto; Sirignano, Cesare; Catalano, Onofrio; Atteno, Mariangela; Costa, Luisa; Caso, Francesco; Peluso, Rosario; Bruner, Vincenzo; Aquino, Maria Maddalena; Del Puente, Antonio; Salvatore, Marco; Scarpa, Raffaele

2012-07-01

340

Tracking immune cells in vivo using magnetic resonance imaging.  

PubMed

The increasing complexity of in vivo imaging technologies, coupled with the development of cell therapies, has fuelled a revolution in immune cell tracking in vivo. Powerful magnetic resonance imaging (MRI) methods are now being developed that use iron oxide- and (19)F-based probes. These MRI technologies can be used for image-guided immune cell delivery and for the visualization of immune cell homing and engraftment, inflammation, cell physiology and gene expression. MRI-based cell tracking is now also being applied to evaluate therapeutics that modulate endogenous immune cell recruitment and to monitor emerging cellular immunotherapies. These recent uses show that MRI has the potential to be developed in many applications to follow the fate of immune cells in vivo. PMID:24013185

Ahrens, Eric T; Bulte, Jeff W M

2013-09-10

341

Magnetic Resonance Imaging Conditional Pacemakers: Rationale, Development and Future Directions  

PubMed Central

Pacemakers and other cardiac implantable electronic devices (CIEDs) have long been considered an absolute contraindication to magnetic resonance imaging (MRI), a crucial and growing imaging modality. In the last 20 years, protocols have been developed to allow MR scanning of CIED patients with a low complication rate. However, this practice has remained limited to a relatively small number of centers, and many pacemaker patients continue to be denied access to clinically indicated imaging. The introduction of MRI conditional pacemakers has provided a widely applicable and satisfactory solution to this problem. Here, the interactions of pacemakers with the MR environment, the results of MR scanning in patients with conventional CIEDs, the development and clinical experience with MRI conditional devices, and future directions are reviewed.

Cronin, Edmond M; Wilkoff, Bruce L

2012-01-01

342

Magnetic resonance imaging using chemical exchange saturation transfer  

NASA Astrophysics Data System (ADS)

Magnetic resonance imaging (MRI) has been widely used as a valuable diagnostic imaging modality that exploits water content and water relaxation properties to provide both structural and functional information with high resolution. Chemical exchange saturation transfer (CEST) in MRI has been recently introduced as a new mechanism of image contrast, wherein exchangeable protons from mobile proteins and peptides are indirectly detected through saturation transfer and are not observable using conventional MRI. It has been demonstrated that CEST MRI can detect important tissue metabolites and byproducts such as glucose, glycogen, and lactate. Additionally, CEST MRI is sensitive to pH or temperature and can calibrate microenvironment dependent on pH or temperature. In this work, we provide an overview on recent trends in CEST MRI, introducing general principles of CEST mechanism, quantitative description of proton transfer process between water pool and exchangeable solute pool in the presence or absence of conventional magnetization transfer effect, and its applications

Park, Jaeseok

2012-10-01

343

Neuroenteric cysts of the brain-comprehensive magnetic resonance imaging  

PubMed Central

Neuroenteric cysts are developmental cysts that should be differentiated from other, more common non-neoplastic cysts as well as cystic neoplasms. While these lesions may have varied imaging findings, T1 hyperintense prepontine lesion due to mucinous/proteinaceous content is characteristic. Location and imaging characteristics aid in formulating the correct diagnosis of neuroepithelial/neuroenteric cysts. Magnetic resonance spectroscopy (MRS) has the specific finding of N-Acetyl Aspartate (NAA)-like peak at 2.02 ppm which is not seen in other cystic lesions. In this study, we aim to discuss the imaging findings of these lesions on conventional and advanced MRI findings and provide radiologic-pathologic correlation. We also briefly describe the pathogenesis, embryology and radiological differential diagnoses of these cysts.

Hingwala, Divyata R; Radhakrishnan, Neelima; Kesavadas, Chandrasekharan; Thomas, Bejoy; Kapilamoorthy, Tirur Raman; Radhakrishnan, Vishnupuri V

2013-01-01

344

Magnetic resonance imaging for diagnosis of early Alzheimer's disease.  

PubMed

A major challenge for neuroimaging is to contribute to the early diagnosis of Alzheimer's disease (AD). In particular, magnetic resonance imaging (MRI) allows detecting different types of structural and functional abnormalities at an early stage of the disease. Anatomical MRI is the most widely used technique and provides local and global measures of atrophy. The recent diagnostic criteria of "mild cognitive impairment due to AD" include hippocampal atrophy, which is considered a marker of neuronal injury. Advanced image analysis techniques generate automatic and reproducible measures both in the hippocampus and throughout the whole brain. Recent modalities such as diffusion-tensor imaging and resting-state functional MRI provide additional measures that could contribute to the early diagnosis but require further validation. PMID:24011982

Colliot, O; Hamelin, L; Sarazin, M

2013-09-04

345

Typical cardiac magnetic resonance imaging findings of cardiac amyloidosis.  

PubMed

We report the case of a 62-year-old man who presented with shortness of breath, lower extremity edema and clinical signs of congestive heart failure. Transthoracic echocardiography demonstrated concentric left ventricular hypertrophy with severe diastolic dysfunction and biatrial enlargement. After aggressive diuresis and clinical improvement, a cardiac magnetic resonance imaging (CMR) examination was performed. The study confirmed the presence of concentric left ventricular hypertrophy with borderline systolic function and impaired diastolic function. Delayed contrast-enhanced imaging indicated diffuse enhancement and lack of adequate signal suppression of the left ventricular myocardium, suggesting the diagnosis of infiltrative heart disease. Rectal biopsy confirmed the diagnosis of amyloidosis. This report presents the typical noninvasive imaging findings of cardiac amyloidosis. PMID:20876061

Floros, Georgios V; Karatzis, Emmanouil N; Andreou, John; Danias, Peter G

346

Magnetic Resonance Imaging (MRI) for the Assessment of Myocardial Viability  

PubMed Central

Executive Summary In July 2009, the Medical Advisory Secretariat (MAS) began work on Non-Invasive Cardiac Imaging Technologies for the Assessment of Myocardial Viability, an evidence-based review of the literature surrounding different cardiac imaging modalities to ensure that appropriate technologies are accessed by patients undergoing viability assessment. This project came about when the Health Services Branch at the Ministry of Health and Long-Term Care asked MAS to provide an evidentiary platform on effectiveness and cost-effectiveness of noninvasive cardiac imaging modalities. After an initial review of the strategy and consultation with experts, MAS identified five key non-invasive cardiac imaging technologies that can be used for the assessment of myocardial viability: positron emission tomography, cardiac magnetic resonance imaging, dobutamine echocardiography, and dobutamine echocardiography with contrast, and single photon emission computed tomography. A 2005 review conducted by MAS determined that positron emission tomography was more sensitivity than dobutamine echocardiography and single photon emission tomography and dominated the other imaging modalities from a cost-effective standpoint. However, there was inadequate evidence to compare positron emission tomography and cardiac magnetic resonance imaging. Thus, this report focuses on this comparison only. For both technologies, an economic analysis was also completed. A summary decision analytic model was then developed to encapsulate the data from each of these reports (available on the OHTAC and MAS website). The Non-Invasive Cardiac Imaging Technologies for the Assessment of Myocardial Viability is made up of the following reports, which can be publicly accessed at the MAS website at: www.health.gov.on.ca/mas or at www.health.gov.on.ca/english/providers/program/mas/mas_about.html Positron Emission Tomography for the Assessment of Myocardial Viability: An Evidence-Based Analysis Magnetic Resonance Imaging for the Assessment of Myocardial Viability: An Evidence-Based Analysis Objective The objective of this analysis is to assess the effectiveness and cost-effectiveness of cardiovascular magnetic resonance imaging (cardiac MRI) for the assessment of myocardial viability. To evaluate the effectiveness of cardiac MRI viability imaging, the following outcomes were examined: the diagnostic accuracy in predicting functional recovery and the impact of cardiac MRI viability imaging on prognosis (mortality and other patient outcomes). Clinical Need: Condition and Target Population Left Ventricular Systolic Dysfunction and Heart Failure Heart failure is a complex syndrome characterized by the heart’s inability to maintain adequate blood circulation through the body leading to multiorgan abnormalities and, eventually, death. Patients with heart failure experience poor functional capacity, decreased quality of life, and increased risk of morbidity and mortality. In 2005, more than 71,000 Canadians died from cardiovascular disease, of which, 54% were due to ischemic heart disease. Left ventricular (LV) systolic dysfunction due to coronary artery disease (CAD) 1 is the primary cause of heart failure accounting for more than 70% of cases. The prevalence of heart failure was estimated at one percent of the Canadian population in 1989. Since then, the increase in the older population has undoubtedly resulted in a substantial increase in cases. Heart failure is associated with a poor prognosis: one-year mortality rates were 32.9% and 31.1% for men and women, respectively in Ontario between 1996 and 1997. Treatment Options In general, there are three options for the treatment of heart failure: medical treatment, heart transplantation, and revascularization for those with CAD as the underlying cause. Concerning medical treatment, despite recent advances, mortality remains high among treated patients, while, heart transplantation is affected by the limited availability of donor hearts and consequently has long waiting lists. The third option, revascularization, is used

2010-01-01

347

Towards Magnetic Resonance Imaging of Semiconducting and Biological Nanostructures  

NASA Astrophysics Data System (ADS)

In recent years a technique combining nuclear magnetic resonance (NMR) and sensitive force microscopy has emerged as a viable method for doing magnetic resonance imaging (MRI) on the nanometer scale [1]. This method, known as magnetic resonance force microscopy (MRFM), has the potential to create three-dimensional (3D), non-destructive, sub-surface images of the density of particular nuclear magnetic moments with isotopic contrast. Resolution better than 10,m has been achieved with ^1H in a single virus particle [2]. Here we discuss the application of this technique to nanobiological samples, such as viruses, small bacteria, or cell membranes, and to various semiconductor nanostructures including quantum wells (QWs) and nanowires (NWs). In particular, we focus on the sample preparation challenges presented by these samples. Transfer and attachment of these sub-micrometer samples to our micrometer-sized force sensor includes the use of a focused ion beam (FIB) technique and manual micromanipulators used together with optical microscopy.[4pt] [1] Nanotechnology 21, 342001 (2010). [2] Proc. Nat. Acad. Sci. U.S.A. 106, 1313 (2009).

Weber, D. P.; Xue, Fei; Peddibhotla, P.; Poggio, M.

2012-02-01

348

Molecular Imaging in Cardiovascular Magnetic Resonance Imaging: Current Perspective and Future Potential  

PubMed Central

The development of novel imaging agents and techniques is allowing some biological events to be imaged in vivo with magnetic resonance imaging (MRI) at the cellular and subcellular level. In this paper, the use of novel gadolinium chelates and superparamagnetic iron oxide nanoparticles for molecular MRI of the cardiovascular system is extensively reviewed. The physical properties of these imaging agents and the pulse sequences best suited to their visualization are extensively discussed. The application of molecular MRI in diseases of the vasculature and myocardium is then reviewed. The clinical experience to date, as well as the promise and potential impact of molecular MRI, is extensively discussed.

Sosnovik, David E.

2008-01-01

349

ADVANCED MAGNETIC RESONANCE IMAGING OF CEREBRAL CAVERNOUS MALFORMATIONS  

PubMed Central

Objective We sought to assess the appearance of cerebral cavernous malformations (CCMs) on magnetic resonance (MR) imaging in murine Ccm1 and Ccm2 gene knockout models, and to develop a technique of lesion localization for correlative pathobiologic studies Methods Brains from eighteen CCM mutant mice (Ccm1+/-Trp53-/- and Ccm2+/-Trp53-/-) and 28 controls were imaged by gradient recalled echo (T2*)-weighted MR at 4.7 T and 14.1 T in vivo and/or ex vivo. After MR imaging, the brains were removed and stained with hematoxylin and eosin and cells were laser microdissected for molecular biologic studies. Results T2*-weighted MR imaging of brains in vivo and ex vivo revealed lesions similar to human CCMs in mutant mice, but not in control animals. Stereotactic localization and hematoxylin and eosin-staining of correlative tissue sections confirmed lesion histology, and revealed other areas of dilated capillaries in the same brains. Some lesions were identified by MR imaging at 14.1 T, but not at 4.7 T. PCR amplification from Ccm1 and ?-actin genes was demonstrated from nucleic acids extracted from laser microdissected lesional and perilesional cells. Conclusions The high field MR imaging techniques offer new opportunities for further investigation of disease pathogenesis in vivo, and the localization, staging and histobiologic dissection of lesions, including the presumed earliest stages of CCM lesion development.

Shenkar, Robert; Venkatasubramanian, Palamadai N.; Wyrwicz, Alice M.; Zhao, Jin-cheng; Shi, Changbin; Akers, Amy; Marchuk, Douglas A.; Awad, Issam A.

2008-01-01

350

Multisensor integration and image recognition using Fuzzy Adaptive Resonance Theory  

NASA Astrophysics Data System (ADS)

The main objective of this work was to investigate the use of 'sensor based real time decision and control technology' applied to actively control the arrestment of aircraft (manned or unmanned). The proposed method is to develop an adaptively controlled system that would locate the aircraft's extended tailhook, predict its position and speed at the time of arrestment, adjust an arresting end effector to actively mate with the arresting hook and remove the aircraft's kinetic energy, thus minimizing the arresting distance and impact stresses. The focus of the work presented in this paper was to explore the use of fuzzy adaptive resonance theorem (fuzzy art) neural network to form a MSI scheme which reduces image data to recognize incoming aircraft and extended tailhook. Using inputs from several image sources a single fused image was generated to give details about range and tailhook characteristics for an F18 naval aircraft. The idea is to partition an image into cells and evaluate each using fuzzy art. Once the incoming aircraft is located in a cell that subimage is again divided into smaller cells. This image is evaluated to locate various parts of the aircraft (i.e., wings, tail, tailhook, etc.). the cell that contains the tailhook provides resolved position information. Multiple images from separate sensors provides opportunity to generate range details overtime.

Singer, Steven M.

1997-03-01

351

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

PubMed

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

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

2004-01-01

352

Current role of magnetic resonance imaging in breast imaging: a primer for the primary care physician.  

PubMed

Magnetic resonance imaging (MRI) is a widely used imaging tool. Interest in the applicability of this modality in the realm of breast imaging has been steadily increasing over the past 25 years. The purpose of this article is to explore the use of contrast-enhanced MRI in breast imaging as it relates to the primary care physician. The mechanism, factors affecting image quality, basics of interpretation guidelines, and the uses and contraindications for this technique are explored. In addition, studies exploring the use of MRI in various areas of breast imaging are presented. It is hoped that the reader will become knowledgeable in the current utility of the tool as it relates to breast imaging. PMID:16322412

Shah, Shinil K; Shah, Shiwan K; Greatrex, Kathleen V

353

Magnetic resonance imaging safety of deep brain stimulator devices.  

PubMed

Magnetic resonance imaging (MRI) has become the standard of care for the evaluation of different neurological disorders of the brain and spinal cord due to its multiplanar capabilities and excellent soft tissue resolution. With the large and increasing population of patients with implanted deep brain stimulation (DBS) devices, a significant proportion of these patients with chronic neurological diseases require evaluation of their primary neurological disease processes by MRI. The presence of an implanted DBS device in a magnetic resonance environment presents potential hazards. These include the potential for induction of electrical currents or heating in DBS devices, which can result in neurological tissue injury, magnetic field-induced device migration, or disruption of the operational aspects of the devices. In this chapter, we review the basic physics of potential interactions of the MRI environment with implanted DBS devices, summarize results from phantom studies and clinical series, and discuss present recommendations for safe MRI in patients with implanted DBS devices. PMID:24112886

Oluigbo, Chima O; Rezai, Ali R

2013-01-01

354

Innovative computing for diagnoses from medical, magnetic-resonance imaging  

SciTech Connect

The author presents a final report on a Laboratory-Directed Research and Development (LDRD) project, Innovative Computing for Diagnoses from Medical, Magnetic-Resonance Imaging, performed during fiscal years 1992 and 1993. The project defined a role for high-performance computing in surgery: the supercomputer can automatically summarize the three-dimensional extents of lesions and other clinically-relevant structures, and can deliver these summaries to workstation-based, augmented-reality environments at the clinical site. The author developed methods and software to make these summaries from the digital data already acquired using clinical, magnetic-resonance machines. In joint work with Albuquerque`s Department of Veterans Affairs Hospital, the author applied this work, and obtained a basis for planning, for rehearsal, and for guidance during surgery.

Diegert, C.

1997-01-01

355

High pressure magnetic resonance imaging with metallic vessels.  

PubMed

High pressure measurements in most scientific fields rely on metal vessels given the superior tensile strength of metals. We introduce high pressure magnetic resonance imaging (MRI) measurements with metallic vessels. The developed MRI compatible metallic pressure vessel concept is very general in application. Macroscopic physical systems are now amenable to spatially resolved nuclear magnetic resonance (NMR) study at variable pressure and temperature. Metallic pressure vessels not only provide inherently high tensile strengths and efficient temperature control, they also permit optimization of the MRI RF probe sensitivity. An MRI compatible pressure vessel is demonstrated with a rock core holder fabricated using non-magnetic stainless steel. Water flooding through a porous rock under pressure is shown as an example of its applications. High pressure NMR spectroscopy plays an indispensable role in several science fields. This work will open new vistas of study for high pressure material science MRI and MR. PMID:21962929

Han, Hui; Ouellette, Matthew; MacMillan, Bryce; Goora, Frederic; MacGregor, Rodney; Green, Derrick; Balcom, Bruce J

2011-09-10

356

Evaluation of myocardial viability with cardiac magnetic resonance imaging.  

PubMed

Assessment of myocardial viability is of clinical and scientific significance. Traditionally, the detection of myocardial viability (either stunning or hibernation) has been used in aiding diagnosis before revascularization, especially in high-risk patients. There is a considerable body of observational evidence showing substantial improvement after revascularization in patients with significant left ventricular dysfunction and myocardial viability. Recent randomized evidence has questioned the benefit of viability testing but must be interpreted with caution. Dobutamine stress echocardiography, nuclear imaging, and cardiovascular magnetic resonance are the mainstays of viability testing and provide information on contractile function, cellular metabolism, and myocardial fibrosis, respectively. Larger, multicenter trials with outcome data are needed to define the nature of viability testing and, particularly, cardiovascular magnetic resonance in moderate-to-severe ischemic cardiomyopathy. PMID:22014488

Grover, Suchi; Srinivasan, Govindarajan; Selvanayagam, Joseph B

357

Nanoscale scanning probe ferromagnetic resonance imaging using localized modes.  

PubMed

The discovery of new phenomena in layered and nanostructured magnetic devices is driving rapid growth in nanomagnetics research. Resulting applications such as giant magnetoresistive field sensors and spin torque devices are fuelling advances in information and communications technology, magnetoelectronic sensing and biomedicine. There is an urgent need for high-resolution magnetic-imaging tools capable of characterizing these complex, often buried, nanoscale structures. Conventional ferromagnetic resonance (FMR) provides quantitative information about ferromagnetic materials and interacting multicomponent magnetic structures with spectroscopic precision and can distinguish components of complex bulk samples through their distinctive spectroscopic features. However, it lacks the sensitivity to probe nanoscale volumes and has no imaging capabilities. Here we demonstrate FMR imaging through spin-wave localization. Although the strong interactions in a ferromagnet favour the excitation of extended collective modes, we show that the intense, spatially confined magnetic field of the micromagnetic probe tip used in FMR force microscopy can be used to localize the FMR mode immediately beneath the probe. We demonstrate FMR modes localized within volumes having 200 nm lateral dimensions, and improvements of the approach may allow these dimensions to be decreased to tens of nanometres. Our study shows that this approach is capable of providing the microscopic detail required for the characterization of ferromagnets used in fields ranging from spintronics to biomagnetism. This method is applicable to buried and surface magnets, and, being a resonance technique, measures local internal fields and other magnetic properties with spectroscopic precision. PMID:20703302

Lee, Inhee; Obukhov, Yuri; Xiang, Gang; Hauser, Adam; Yang, Fengyuan; Banerjee, Palash; Pelekhov, Denis V; Hammel, P Chris

2010-08-12

358

Pattern recognition of magnetic resonance images with application to atherosclerosis  

SciTech Connect

Magnetic resonance imaging provides excellent soft tissue contrast enabling the non-invasive visualization of soft tissue diseases. The quantification of tissues visible in MR images would significantly increase the diagnostic information available. While tissue selection methods exist for CT images, those same methods do not work with MR images. This dissertation focuses on the application of image processing and pattern recognition techniques to MR images for the identification and quantification of soft tissues, atherosclerosis in particular. Atherosclerosis is a chronic disease of human arteries responsible for significant mortality and medical expense. Current diagnostic methods are invasive and carry significant risk. Supervised pattern recognition methods were investigated for tissue identification in MR images. The classifiers were trained A Fisher linear classifier successfully identified the tissues of interest from MR images of excised arteries, performing better than a minimum distance to the means classifier. Quantitative measures of the disease state were computed from the results and 3-D displays were generated of the diseased anatomy. For tissue in vivo, adequate histology can be difficult to collect, increasing the difficulty of training the classifiers and making the results less accurate. Cluster analysis was used in this dissertation to generate the training information. A new cluster analysis method was developed. ISODATA was modified to use hierarchical stopping rules. The new method was tested in a Monte Carlo study and with real world data sets. Comparisons were made with published methods using the same data. An information theoretic criterion, the CAIC, was found to be an excellent criteria for hierarchical stopping rules.

Carman, C.S.

1989-01-01

359

Facial recognition from volume-rendered magnetic resonance imaging data.  

PubMed

Three-dimensional (3-D) reconstructions of computed tomography (CT) and magnetic resonance (MR) brain imaging studies are a routine component of both clinical practice and clinical and translational research. A side effect of such reconstructions is the creation of a potentially recognizable face. The Health Insurance Portability and Accountability Act of 1996 (HIPAA) Privacy Rule requires that individually identifiable health information may not be used for research unless identifiers that may be associated with the health information including "Full face photographic images and other comparable images ..." are removed (de-identification). Thus, a key question is: Are reconstructed facial images comparable to full-face photographs for the purpose of identification? To address this question, MR images were selected from existing research repositories and subjects were asked to pair an MR reconstruction with one of 40 photographs. The chance probability that an observer could match a photograph with its 3-D MR image was 1 in 40 (0.025), and we considered 4 successes out of 40 (4/40, 0.1) to indicate that a subject could identify persons' faces from their 3-D MR images. Forty percent of the subjects were able to successfully match photographs with MR images with success rates higher than the null hypothesis success rate. The Blyth-Still-Casella 95% confidence interval for the 40% success rate was 29%-52%, and the 40% success rate was significantly higher ( P < 0.001) than our null hypothesis success rate of 1 in 10 (0.10). PMID:19129018

Prior, Fred W; Brunsden, Barry; Hildebolt, Charles; Nolan, Tracy S; Pringle, Michael; Vaishnavi, S Neil; Larson-Prior, Linda J

2009-01-01

360

Magnetic Resonance Imaging Assessment of Gluteal Fat Grafts  

Microsoft Academic Search

Backgrounds  One goal of lipoplasty is to create a round and projected buttock contour. Despite multiple papers evaluating lipoinjection,\\u000a controversies still remain.\\u000a \\u000a \\u000a \\u000a Methods  This report describes a series of patients who underwent liposuction, gluteal lipoinjection, and evaluation with magnetic\\u000a resonance imaging (MRI). From January 2003 to January 2004, the patients scheduled for contour surgery by the investigators\\u000a were evaluated using MRI, photographic

2006-01-01

361

Role of functional magnetic resonance imaging in drug discovery  

PubMed Central

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

Paulus, Martin P.; Stein, Murray B.

2010-01-01

362

Quantification of Liver Fat with Magnetic Resonance Imaging  

PubMed Central

Intracellular fat accumulation is common feature of liver disease. Intracellular fat (steatosis) is the histological hallmark of non-alcoholic fatty liver disease (NAFLD) but also may occur with alcohol abuse, viral hepatitis, HIV and genetic lipodystrophies, and chemotherapy. This article reviews emerging magnetic resonance imaging techniques that attempt to quantify liver fat. The content provides an overview of fatty liver disease and diseases where fat is an important disease feature. Also discussed is the current use and limitation of non-targeted biopsy in diffuse liver disease, and why quantitative non-invasive biomarkers of liver fat would be beneficial.

Reeder, Scott B.; Sirlin, Claude

2010-01-01

363

Fast imaging for magnetic resonance electrical impedance tomography  

PubMed Central

In magnetic resonance electrical impedance tomography (MREIT), currents are injected into an object, the resulting magnetic flux density measured using MRI, and the conductivity distribution reconstructed using these MRI data. The relatively long acquisition times of conventional MREIT methods limit the signal averaging rate and are susceptible to motion artifacts. In this study, we reconstructed the conductivity distribution of an agarose gel phantom from data acquired in under a minute using a single shot, spin echo, echo planar imaging (SS-SEPI) pulse sequence. The results demonstrate that SS-SEPI can be used for MREIT data acquisition.

Hamamura, Mark J.; Muftuler, L. Tugan

2008-01-01

364

Low-field magnetic resonance imaging of gases  

SciTech Connect

This is the final report of a six-month, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The main goal of this project was to develop the capability to conduct low-field magnetic resonance imaging of hyper-polarized noble gas nuclei and of thermally polarized protons in water. The authors constructed a versatile low-field NMR system using a SQUID gradiometer detector inside a magnetically shielded room. This device has sufficient low-field sensitivity to detect the small signals associated with NMR at low magnetic fields.

Schmidt, D.M.; Espy, M.A.

1998-11-01

365

[Tethered spinal cord and lipoma. Contribution of magnetic resonance imaging].  

PubMed

A 12 year-old boy was investigated for progressive deformity of the left foot developing over 2 years. The foot was hollow with equinus varus and claw toes. Signs of a lesion of left L5 and S1 roots were present and spina bifida at L5 was noted on X-rays. Magnetic resonance imaging (MRI) showed a tethered spinal cord associated with a lipoma at the level of the S1 vertebra. Modes of presentation and physiopathology of disorders related to tethered cords are reviewed and the diagnostic value of MRI is emphasized. PMID:3538290

Awada, A; Chatta, G; Majdalani, A; Gautier, J C

1986-01-01

366

Langevin equation approach to diffusion magnetic resonance imaging  

NASA Astrophysics Data System (ADS)

The normal phase diffusion problem in magnetic resonance imaging (MRI) is treated by means of the Langevin equation for the phase variable using only the properties of the characteristic function of Gaussian random variables. The calculation may be simply extended to anomalous diffusion using a fractional generalization of the Langevin equation proposed by Lutz [E. Lutz, Phys. Rev. E 64, 051106 (2001)] pertaining to the fractional Brownian motion of a free particle coupled to a fractal heat bath. The results compare favorably with diffusion-weighted experiments acquired in human neuronal tissue using a 3 T MRI scanner.

Cooke, Jennie M.; Kalmykov, Yuri P.; Coffey, William T.; Kerskens, Christian M.

2009-12-01

367

Ventilation and perfusion magnetic resonance imaging of the lung  

PubMed Central

Summary A close interaction between the respiratory pump, pulmonary parenchyma and blood circulation is essential for a normal lung function. Many pulmonary diseases present, especially in their initial phase, a variable regional impairment of ventilation and perfusion. In the last decades various techniques have been established to measure the lung function. Besides the global pulmonary function tests (PFTs) imaging techniques gained increasing importance to detect local variations in lung function, especially for ventilation and perfusion assessment. Imaging modalities allow for a deeper regional insight into pathophysiological processes and enable improved planning of invasive procedures. In contrast to computed tomography (CT) and the nuclear medicine techniques, magnetic resonance imaging (MRI), as a radiation free imaging modality gained increasing importance since the early 1990 for the assessment of pulmonary function. The major inherent problems of lung tissue, namely the low proton density and the pulmonary and cardiac motion, were overcome in the last years by a constant progress in MR technology. Some MR techniques are still under development, a process which is driven by scientific questions regarding the physiology and pathophysiology of pulmonary diseases, as well as by the need for fast and robust clinically applicable imaging techniques as safe therapy monitoring tools. MRI can be considered a promising ionizing-free alternative to techniques like CT or nuclear medicine techniques for the evaluation of lung function. The goal of this article is to provide an overview on selected MRI techniques for the assessment of pulmonary ventilation and perfusion.

Bauman, Grzegorz; Eichinger, Monika

2012-01-01

368

Who should have breast magnetic resonance imaging evaluation?  

PubMed

During the last two decades, tremendous advances have been made in the performance and interpretation of breast magnetic resonance imaging (MRI) examinations. Technical requirements for optimal breast imaging including the requirement for a breast MRI biopsy system are now being defined as part of a voluntary American College of Radiology (ACR) breast MRI accreditation program. The ACR BI-RADS (Breast Imaging Reporting and Data System) lexicon for breast MRI has brought uniformity to the interpretation of breast MRI examinations. With these advances in imaging technique, interpretation guidelines, and increasing availability of MR-compatible breast biopsy systems, MRI of the breast is rapidly gaining popularity in clinical practice in both the diagnostic setting and, more recently, in the screening setting. The clinical indications for breast MRI, however, remain to be defined. There are clinical indications that have emerged where MRI, as an adjunct to mammography, seems to be the imaging study of choice. There are other indications, specifically breast cancer staging, in which MRI is being utilized with increasing frequency, but in which controversy persists. PMID:18258977

Orel, Susan

2008-02-10

369

Off-center magnetic resonance imaging with permanent magnets  

NASA Astrophysics Data System (ADS)

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

Abele, Manlio G.; Rusinek, Henry

2008-04-01

370

Quantitative Magnetic Resonance Imaging of 3-He Gas Transport  

NASA Astrophysics Data System (ADS)

In magnetic resonance (MR) imaging the use of laser-polarized 3-He dramatically increases detection sensitivity and facilitates gas visualization. Here, the potential use of 3-He MR imaging for quantifying gas transport in the respiratory tract of laboratory rodents is examined by studying laminar flow in a straight pipe with a diameter comparable to the rat trachea (˜ 3.2 mm). At physiological flow rates (˜ 4 ml/s), laminar-like features are observed in 2D images of axial diffusion, and the structure of observed flow lamina differs significantly from predictions based on the Navier-Stokes equations. To reconcile these results, we formulate a statistical model of gas transport that accounts for Brownian motion on the imaging time scale. The model uses the 2D solution to the diffusion equation to describe how diffusing gas molecules sample the stationary flow field. The effects on MR measurements are then formulated in terms of the mean flow velocity, higher order correlation functions, and the details of data acquisition. Comparison between modeling and experiment shows that MR imaging results are accurately predicted for different gas mixtures and acquisition conditions. The model is generally applicable to any flow conduit, resulting in a quantitative basis for noninvasive gas transport studies.

Jacob, Richard E.; Minard, Kevin R.

2007-03-01

371

Intensity inhomogeneity correction of magnetic resonance images using patches  

NASA Astrophysics Data System (ADS)

This paper presents a patch-based non-parametric approach to the correction of intensity inhomogeneity from magnetic resonance (MR) images of the human brain. During image acquisition, the inhomogeneity present in the radio-frequency coil, is usually manifested on the reconstructed MR image as a smooth shading effect. This artifact can significantly deteriorate the performance of any kind of image processing algorithm that uses intensities as a feature. Most of the current inhomogeneity correction techniques use explicit smoothness assumptions on the inhomogeneity field, which sometimes limit their performance if the actual inhomogeneity is not smooth, a problem that becomes prevalent in high fields. The proposed patch-based inhomogeneity correction method does not assume any parametric smoothness model, instead, it uses patches from an atlas of an inhomogeneity-free image to do the correction. Preliminary results show that the proposed method is comparable to N3, a current state of the art method, when the inhomogeneity is smooth, and outperforms N3 when the inhomogeneity contains non-smooth elements.

Roy, Snehashis; Carass, Aaron; Bazin, Pierre-Louis; Prince, Jerry L.

2011-03-01

372

Prostate cancer magnetic resonance imaging (MRI): multidisciplinary standpoint  

PubMed Central

Prostate cancer is the most common cancer diagnosed in men and a leading cause of death. Accurate assessment is a prerequisite for optimal clinical management and therapy selection of prostate cancer. There are several parameters and nomograms to differentiate between patients with clinically insignificant disease and patients in need of treatment. Magnetic resonance imaging (MRI) is a technique which provides more detailed anatomical images due to high spatial resolution, superior contrast resolution, and multiplanar capability. State-of-the-art MRI techniques, such as diffusion weighted imaging (DWI), MR spectroscopic imaging (MRSI), dynamic contrast enhanced MRI (DCE-MRI), improve interpretation of prostate cancer imaging. In this article, we review the major role of MRI in the advanced management of prostate cancer to noninvasively improve tumor staging, biologic potential, treatment planning, therapy response, local recurrence, and to guide target biopsy for clinical suspected cancer with previous negative biopsy. Finally, future challenges and opportunities in prostate cancer management in the area of functional MRI are discussed as well.

Li, Liang; Feng, Zhaoyan; Hu, Zhiquan; Wang, Guoping; Yuan, Xianglin; Wang, He; Hu, Daoyu

2013-01-01

373

Method of magnetic resonance imaging of the liver and spleen  

SciTech Connect

A method is described of imaging a tumor in the liver or spleen of a human subject, comprising: (a) parenterally administering to the human subject prior to magnetic resonance imaging (MRI) examination an aqueous suspension composed essentially of 1.5 to 8 micron diameter microspheres, the microspheres having a biodegradeable matrix with a contrast agent dispersed therein selected from the group consisting of paramagnetic and ferromagnetic contrast agents. The quantity of the microspheres, administered are effective to appreciably reduce the T/sub 2/ relaxation time of the subjects liver and/or spleen; (b) delaying the examination until the microspheres have been segregated by the reticuloendothelial system and are concentrated in the liver and spleen; and then (c) carrying out an MRI examination of the liver and/or spleen by T/sub 2/ imaging or mixed T/sub 1/ and T/sub 2/ imaging to obtain an image in which the normal liver or spleen tissues appear dark and the tumor appears light with distinct margins.

Widder, K.J.

1987-06-23

374

Image guided interstitial laser thermotherapy: a canine model evaluated by magnetic resonance imaging and quantitative autoradiography  

Microsoft Academic Search

Summary Objective. To determine the applicability and safety of a new canine model suitable for correlative magnetic resonance imaging (MRI) studies and morphological\\/pathophysiological examination over time after interstitial laser thermotherapy (ILTT) in brain tissue. Material and methods. A laser fibre (Diode Laser 830?nm) with an integrated temperature feedback system was inserted into the right frontal white matter in 18 dogs

A. Muacevic; M. Peller; L. Ruprecht; D. Berg; L. Fend; R. Sroka; H. J. Reulen; M. Reiser; J. Ch. Tonn; F. W. Kreth

2005-01-01

375

Nuclear magnetic resonance imaging of flow using the rotating ultra-fast imaging sequence  

Microsoft Academic Search

Fluid dynamics has a wide range of applications including biomedical. Traditionally, experimental fluid mechanics has involved invasive techniques to study flow dynamics. The advent of magnetic resonance imaging (MRI) in the 1970's presented a powerful new noninvasive, diagnostic tool for biomedical applications. However, the slow acquisition times associated with MRI limited its usefulness in vivo for regions with flow and

H. Michael Gach

1998-01-01

376

Manifold Learning Techniques in Image Analysis of High-dimensional Diffusion Tensor Magnetic Resonance Images  

Microsoft Academic Search

Diffusion Tensor magnetic resonance imaging (DT-MRI) provides a comprehensive characterization of white matter (WM) in the brain and therefore, plays a crucial role in the investigation of diseases in which WM is suspected to be compromised such as multiple sclerosis and neuropsychiatric disorders like schizophrenia. However changes induced by pathology may be subtle and affected regions of the brain can

Parmeshwar Khurd; Sajjad Baloch; Ruben C. Gur; Christos Davatzikos; Ragini Verma

2007-01-01

377

Myocardial perfusion imaging: clinical experience and recent progress in radionuclide scintigraphy and magnetic resonance imaging  

Microsoft Academic Search

In the past 20 years, radionuclide scintigraphy has proven to be a sensitive clinical tool in the assessment of myocardial perfusion abnormalities. Magnetic resonance imaging may also be used to study myocardial perfusion, but its potential value still has to emerge in the clinical setting. This review addresses the potential and achievements of both methods in clinical cardiology.

Cess A. Visser; Jan T. Keijer; Jeroen J. Bax; Albert C. van Rossum; Frans C. Visser

1997-01-01

378

A comparison of magnetic resonance imaging methods for fluid content imaging in porous media.  

PubMed

Quantitative measurements are important for imaging fluid content in porous media. Conventional MRI methods suffer from contrast because of relaxation times in porous media, resulting in measurements of apparent fluid content, not the true fluid content. We compare four magnetic resonance imaging methods for fluid content imaging in several water-saturated reservoir core plugs: frequency-encoded spin echo, single point ramped imaging with T1 enhancement, hybrid spin echo single point imaging (SE-SPI), and T2 mapping SE-SPI. 1-D profiles obtained with each method were compared in terms of image quality, image sensitivity, and quantification of water content. The image quality of short T2 lifetime samples suffered from blurring in hybrid SE-SPI images. Image sensitivity was the highest in the profiles obtained with frequency-encoded spin echo. The quantification of frequency-encoded spin echo, T2 mapping SE-SPI, and hybrid SE-SPI suffered in core plugs with a significant population of short T2 components because of T2 attenuation. Overall, single point ramped imaging with T1 enhancement was found to be the most general method for fluid content imaging. PMID:23483683

Muir, Colleen E; Balcom, Bruce J

2013-03-11

379

Echo-planar imaging: Magnetic resonance imaging in a fraction of a second  

SciTech Connect

Progress has recently been made in implementing magnetic resonance imaging (MRI) techniques that can be used to obtain images in a fraction of a second rather than in minutes. Echo-planar imaging (EPI) uses only one nuclear spin excitation per image and lends itself to a variety of critical medical and scientific applications. Among these are evaluation of cardiac function in real time, mapping of water diffusion and temperature in tissue, mapping of organ blood pool and perfusion, functional imaging of the central nervous system, depiction of blood and cerebrospinal fluid flow dynamics, and movie imaging of the mobile fetus in utero. Through shortened patient examination times, higher patient throughput, and lower cost per MRI examination, EPI may become a powerful tool for early diagnosis of some common and potentially treatable diseases such as ischemic heart disease, stroke, and cancer.

Stehling, M.K. (Friedrich Alexander Univ., Erlangen (West Germany) Siemens AG, Erlangen (West Germany)); Turner, R. (National Institutes of Health, Bethesda, MD (United States)); Mansfield, P. (Univ. of Nottingham (England))

1991-10-04

380

Echo-Planar Imaging: Magnetic Resonance Imaging in a Fraction of a Second  

NASA Astrophysics Data System (ADS)

Progress has recently been made in implementing magnetic resonance imaging (MRI) techniques that can be used to obtain images in a fraction of a second rather than in minutes. Echo-planar imaging (EPI) uses only one nuclear spin excitation per image and lends itself to a variety of critical medical and scientific applications. Among these are evaluation of cardiac function in real time, mapping of water diffusion and temperature in tissue, mapping of organ blood pool and perfusion, functional imaging of the central nervous system, depiction of blood and cerebrospinal fluid flow dynamics, and movie imaging of the mobile fetus in utero. Through shortened patient examination times, higher patient throughput, and lower cost per MRI examination, EPI may become a powerful tool for early diagnosis of some common and potentially treatable diseases such as ischemic heart disease, stroke, and cancer.

Stehling, Michael K.; Turner, Robert; Mansfield, Peter

1991-10-01

381

Pulmonary functional magnetic resonance imaging for paediatric lung disease.  

PubMed

A better understanding of the anatomic structure and physiological function of the lung is fundamental to understanding the pathogenesis of pulmonary disease and how to design and deliver better treatments and measure response to intervention. Magnetic resonance imaging (MRI) with the hyperpolarised noble gases helium-3 ((3)He) and xenon-129 ((129)Xe) provides both structural and functional pulmonary measurements, and because it does not require the use of x-rays or other ionising radiation, offers the potential for intensive serial and longitudinal studies in paediatric patients. These facts are particularly important in the evaluation of chronic lung diseases such as asthma and cystic fibrosis- both of which can be considered paediatric respiratory diseases with unmet therapy needs. This review discusses MRI-based imaging methods with a focus on hyperpolarised gas MRI. We also discuss the strengths and limitations as well as the future work required for clinical translation towards paediatric respiratory disease. PMID:23522599

Kirby, Miranda; Coxson, Harvey O; Parraga, Grace

2013-03-20

382

Direct Neural Imaging using Ultra-Low Field Magnetic Resonance  

NASA Astrophysics Data System (ADS)

An enduring challenge in neuroscience is the accurate in vivo mapping of neural activity with high spatial and temporal resolution. A method being developed by our group tries to meet this challenge by using Ultra-Low Field (ULF) MRI. Other groups have attempted direct neural imaging (DNI) using high field MRI. However, the use of ULF presents two advantages. First, the susceptibility artifact at high fields, which masks the DNI signal, is negligible at low fields. Second, the reduced Larmor frequency at ULF may overlap with the frequency spectrum of the neural magnetic field, resonantly enhancing the MRI signal. In this presentation, I will first show our custom-built ULF MRI setups that have successfully produced ULF anatomical images. I will then highlight the numerous studies we have done to investigate the feasibility of DNI with these systems, including both experimental and theoretical studies.

Maskaly, Karlene; Espy, Michelle; Flynn, Mark; Gomez, John; Kraus, Robert; Matlashov, Andrei; Mosher, John; Newman, Shaun; Owens, Tuba; Peters, Mark; Sandin, J.; Schultz, Larry; Urbaitis, Algis; Volegov, Petr; Zotev, Vadim

2009-03-01

383

Magnetic resonance imaging of the pericardium: normal and pathologic findings  

SciTech Connect

Twenty normal subjects and ten patients with pericardial abnormalities underwent ECG-gated magnetic resonance (MR) imaging of the thorax using a 0.35-tesla superconducting system. The patients with pericardial abnormalities were also evaluated with serial chest radiography, ultrasound, computed tomography, and/or angiography. ECG gating was necessary to identify the normal pericardium, which was visualized as a 1- to 2-mm-wide curvilinear structure of low signal intensity. Pericardial thickening in constrictive pericarditis was clearly delineated on gated MR images. Pericardial inflammation caused a marked increase in signal intensity as well as thickening of the pericardium. Pericardial effusions and pericardial adhesions were also demonstrated. A simple pericardial cyst and a complex pericardial mass were identified and differentiated from pericardial fat and diaphragmatic eventration. MR appears to be an important modality for the evaluation of pericardial disease.

Stark, D.D.; Higgins, C.B.; Lanzer, P.; Lipton, M.J.; Schiller, N.; Crooks, L.E.; Botvinick, E.B.; Kaufman, L.

1984-02-01

384

Clinical significance of magnetic resonance imaging findings in rectal cancer  

PubMed Central

Staging of rectal cancer is essential to help guide clinicians to decide upon the correct type of surgery and determine whether or not neoadjuvant therapy is indicated. Magnetic resonance imaging (MRI) is currently one of the most accurate modalities on which to base treatment decisions for patients with rectal cancer. MRI can accurately detect the mesorectal fascia, assess the invasion of the mesorectum or surrounding organs and predict the circumferential resection margin. Although nodal disease remains a difficult radiological diagnosis, new lymphographic agents and diffusion weighted imaging may allow identification of metastatic nodes by criteria other then size. In light of this, we have reviewed the literature on the accuracy of specific MRI findings for staging the local extent of primary rectal cancer. The aim of this review is to establish a correlation between MRI findings, prognosis, and available treatment options.

Bellows, Charles F; Jaffe, Bernard; Bacigalupo, Lorenzo; Pucciarelli, Salvatore; Gagliardi, Guiseppe

2011-01-01

385

Value of magnetic resonance imaging in guiding atrial fibrillation management.  

PubMed

Atrial fibrillation (AF) is the most common arrhythmia encountered in clinical practice today. Until recently, the therapeutic approaches for AF have been limited by imperfect risk prediction models and suboptimal approaches for AF ablation. Magnetic resonance imaging (MRI) for the detection of left atrial (LA) fibrosis and correlation of these structural remodelling changes to outcomes of stroke, AF recurrence, and congestive heart failure have provided us with information to optimize the care of our patients with AF based on screening for fibrotic atrial cardiomyopathy, for which AF is the arrhythmic manifestation. These data allow us to bring these new imaging modalities to the forefront of AF management and the delivery of personalized medicine. Future developments promise to improve the outcomes and safety for AF and fibrotic atrial cardiomyopathy. PMID:24074971

Han, Frederick T; Akoum, Nazem; Marrouche, Nassir

2013-10-01

386

The role of magnetic resonance imaging in oncology.  

PubMed

Conventional diagnostic magnetic resonance imaging (MRI) techniques have focused on improving the spatial resolution and image acquisition speed (whole-body MRI) or on new contrast agents. Most advances in MRI go beyond morphologic study to obtain functional and structural information in vivo about different physiological processes of tumor microenvironment, such as oxygenation levels, cellular proliferation, or tumor vascularization through MRI analysis of some characteristics: angiogenesis (perfusion MRI), metabolism (MRI spectroscopy), cellularity (diffusion-weighted MRI), lymph node function, or hypoxia [blood-oxygen-level-dependent (BOLD) MRI]. We discuss the contributions of different MRI techniques than must be integrated in oncologic patients to substantially advance tumor detection and characterization risk stratification, prognosis, predicting and monitoring response to treatment, and development of new drugs. PMID:20851801

González Hernando, Concepción; Esteban, Laura; Cañas, Teresa; Van den Brule, Enrique; Pastrana, Miguel

2010-09-01

387

Role for magnetic resonance imaging in coccydynia with sacrococcygeal dislocation.  

PubMed

Sacrococcygeal dislocation is among the many causes of coccydynia. The etiological diagnosis of this fairly rare condition is difficult. Dynamic imaging is the only means of documenting the dislocation. We describe two cases of sacrococcygeal dislocation in patients presenting with coccydynia. Both patients reported a history of trauma in the more or less remote past, with no clear correlation with pain onset. Magnetic resonance imaging (MRI) of the sacrococcygeal junction showed local inflammatory lesions (bursitis, sacrococcygeal arthritis), providing a rationale for a local procedure. Analgesic therapy was inadequately effective and a local glucocorticoid injection into the sacrococcygeal junction was therefore recommended. One of the patients accepted this procedure and subsequently reported complete resolution of the symptoms. PMID:23098924

Trouvin, Anne-Priscille; Goeb, Vincent; Vandhuick, Thibault; Michelin, Paul; Lequerré, Thierry; Vittecoq, Olivier

2012-10-23

388

Cardiovascular Magnetic Resonance Imaging of Myocardial Infarction, Viability, and Cardiomyopathies  

PubMed Central

Cardiovascular magnetic resonance provides the opportunity for a truly comprehensive evaluation of patients with a history of MI, with regards to characterizing the extent of disease, impact on LV function and degree of viable myocardium. The use of contrast-enhanced CMR for first-pass perfusion and late gadolinium enhancement is a powerful technique for delineating areas of myocardial ischemia and infarction. Using a combination of T2-weighted and contrast-enhanced CMR images, information about the acuity of an infarct can be obtained. There is an extensive amount of literature using contrast-enhanced CMR to predict myocardial functional recovery with revascularization in patients with ischemic cardiomyopathies. In addition, CMR imaging in patients with cardiomyopathies can distinguish between ischemic and non-ischemic etiologies, with the ability to further characterize the underlying pathology for non-ischemic cardiomyopathies.

West, Amy M.; Kramer, Christopher M.

2010-01-01

389

23Na magnetic resonance imaging: distribution of brine in muscle.  

PubMed

Magnetic resonance imaging (MRI) has been used to characterize tissues in morphological studies. Here, 23Na NMR imaging was used to study the distribution in muscle of brine (5 M NaCl), injected before onset of rigor mortis. First, the distribution of brine was monitored in excised muscle from rabbits for 6 hr following arterial brine injection. Immediately after injection, distribution was clearly heterogeneous. After 6 hr, a steady state was achieved but the observed brine distribution was not fully homogeneous. Second, the same was done for ham processed in various ways (tumbling, cooking). Tumbling increased the homogeneity of distribution in our experimental conditions but only cooking afforded full homogenization of brine in ham. Concentrations of NMR-visible sodium in the muscles were appreciably lower than the expected values calculated from the volume of injected brine. The invisible sodium presumably has T2 values which are too short compared with the echo time in our conventional spectrometer. PMID:8295500

Renou, J P; Benderbous, S; Bielicki, G; Foucat, L; Donnat, J P

1994-01-01

390

Statistical reconstruction algorithms for continuous wave electron spin resonance imaging.  

PubMed

Electron spin resonance imaging (ESRI) is an important branch of ESR that deals with heterogeneous samples ranging from semiconductor materials to small live animals and even humans. ESRI can produce either spatial images (providing information about the spatially dependent radical concentration) or spectral-spatial images, where an extra dimension is added to describe the absorption spectrum of the sample (which can also be spatially dependent). The mapping of oxygen in biological samples, often referred to as oximetry, is a prime example of an ESRI application. ESRI suffers frequently from a low signal-to-noise ratio (SNR), which results in long acquisition times and poor image quality. A broader use of ESRI is hampered by this slow acquisition, which can also be an obstacle for many biological applications where conditions may change relatively quickly over time. The objective of this work is to develop an image reconstruction scheme for continuous wave (CW) ESRI that would make it possible to reduce the data acquisition time without degrading the reconstruction quality. This is achieved by adapting the so-called "statistical reconstruction" method, recently developed for other medical imaging modalities, to the specific case of CW ESRI. Our new algorithm accounts for unique ESRI aspects such as field modulation, spectral-spatial imaging, and possible limitation on the gradient magnitude (the so-called "limited angle" problem). The reconstruction method shows improved SNR and contrast recovery vs. commonly used back-projection-based methods, for a variety of simulated synthetic samples as well as in actual CW ESRI experiments. PMID:23644350

Kissos, Imry; Levit, Michael; Feuer, Arie; Blank, Aharon

2013-04-17

391

Acute stroke magnetic resonance imaging: current status and future perspective.  

PubMed

Cerebral stroke is one of the most frequent causes of permanent disability or death in the western world and a major burden in healthcare system. The major portion is caused by acute ischemia due to cerebral artery occlusion by a clot. The minority of strokes is related to intracerebral hemorrhage or other sources. To limit the permanent disability in ischemic stroke patients resulting from irreversible infarction of ischemic brain tissue, major efforts were made in the last decade. To extend the time window for thrombolysis, which is the only approved therapy, several imaging parameters in computed tomography and magnetic resonance imaging (MRI) have been investigated. However, the current guidelines neglect the fact that the portion of potentially salvageable ischemic tissue (penumbra) is not dependent on the time window but the individual collateral blood flow. Within the last years, the differentiation of infarct core and penumbra with MRI using diffusion-weighted images (DWI) and perfusion imaging (PI) with parameter maps was established. Current trials transform these technical advances to a redefined patient selection based on physiological parameters determined by MRI. This review article presents the current status of MRI for acute stroke imaging. A special focus is the ischemic stroke. In dependence on the pathophysiology of cerebral ischemia, the basic principle and diagnostic value of different MRI sequences are illustrated. MRI techniques for imaging of the main differential diagnoses of ischemic stroke are mentioned. Moreover, perspectives of MRI for imaging-based acute stroke treatment as well as monitoring of restorative stroke therapy from recent trials are discussed. PMID:19967531

Kloska, Stephan P; Wintermark, Max; Engelhorn, Tobias; Fiebach, Jochen B

2009-12-05

392

Narrow band deformable registration of prostate magnetic resonance imaging, magnetic resonance spectroscopic imaging, and computed tomography studies  

SciTech Connect

Purpose: Endorectal (ER) coil-based magnetic resonance imaging (MRI) and magnetic resonance spectroscopic imaging (MRSI) is often used to obtain anatomic and metabolic images of the prostate and to accurately identify and assess the intraprostatic lesions. Recent advancements in high-field (3 Tesla or above) MR techniques affords significantly enhanced signal-to-noise ratio and makes it possible to obtain high-quality MRI data. In reality, the use of rigid or inflatable endorectal probes deforms the shape of the prostate gland, and the images so obtained are not directly usable in radiation therapy planning. The purpose of this work is to apply a narrow band deformable registration model to faithfully map the acquired information from the ER-based MRI/MRSI onto treatment planning computed tomography (CT) images. Methods and Materials: A narrow band registration, which is a hybrid method combining the advantages of pixel-based and distance-based registration techniques, was used to directly register ER-based MRI/MRSI with CT. The normalized correlation between the two input images for registration was used as the metric, and the calculation was restricted to those points contained in the narrow bands around the user-delineated structures. The narrow band method is inherently efficient because of the use of a priori information of the meaningful contour data. The registration was performed in two steps. First, the two input images were grossly aligned using a rigid registration. The detailed mapping was then modeled by free form deformations based on B-spline. The limited memory Broyden-Fletcher-Goldfarb-Shanno algorithm (L-BFGS), which is known for its superior performance in dealing with high-dimensionality problems, was implemented to optimize the metric function. The convergence behavior of the algorithm was studied by self-registering an MR image with 100 randomly initiated relative positions. To evaluate the performance of the algorithm, an MR image was intentionally distorted, and an attempt was then made to register the distorted image with the original one. The ability of the algorithm to recover the original image was assessed using a checkerboard graph. The mapping of ER-based MRI onto treatment planning CT images was carried out for two clinical cases, and the performance of the registration was evaluated. Results: A narrow band deformable image registration algorithm has been implemented for direct registration of ER-based prostate MRI/MRSI and CT studies. The convergence of the algorithm was confirmed by starting the registration experiment from more than 100 different initial conditions. It was shown that the technique can restore an MR image from intentionally introduced deformations with an accuracy of approximately 2 mm. Application of the technique to two clinical prostate MRI/CT registrations indicated that it is capable of producing clinically sensible mapping. The whole registration procedure for a complete three-dimensional study (containing 256 x 256 x 64 voxels) took less than 15 min on a standard personal computer, and the convergence was usually achieved in fewer than 100 iterations. Conclusions: A deformable image registration procedure suitable for mapping ER-based MRI data onto planning CT images was presented. Both hypothetical tests and patient studies have indicated that the registration is reliable and provides a valuable tool to integrate the ER-based MRI/MRSI information to guide prostate radiation therapy treatment.

Schreibmann, Eduard [Department of Radiation Oncology, Stanford University School of Medicine Stanford, CA (United States); Xing Lei [Department of Radiation Oncology, Stanford University School of Medicine Stanford, CA (United States)]. E-mail: lei@reyes.stanford.edu

2005-06-01

393

Quantification issues in arterial spin labeling perfusion magnetic resonance imaging.  

PubMed

Arterial spin labeling (ASL) perfusion magnetic resonance imaging has gained wide acceptance for its value in clinical and neuroscience applications during recent years. Its capability for noninvasive and absolute perfusion quantification is a key characteristic that makes ASL attractive for many clinical applications. In the present review, we discuss the main parameters or factors that affect the reliability and accuracy of ASL perfusion measurements. Our secondary goal was to outline potential solutions that may improve the reliability and accuracy of ASL in clinical settings. It was found that, through theoretical analyses, flow quantification is most sensitive to tagging efficiency and estimation of the equilibrium magnetization of blood signal (M(0b)). Variations of blood T1 have a greater effect on perfusion quantification than variations of tissue T1. Arterial transit time becomes an influential factor when it is longer than the postlabeling delay time. The T2's of blood and tissue impose minimal effects on perfusion calculation at field strengths equal to or lower than 3.0 T. Subsequently, we proposed various approaches for in vivo estimation or calibration of the above parameters, such as the use of phase-contrast magnetic resonance imaging for calibration of the labeling efficiency as well as the use of inversion recovery TrueFISP (true fast imaging with steady-state precession) sequence for blood T1 mapping. We also list representative clinical cases in which implicit assumptions for ASL perfusion quantification may be violated, such as the venous outflow effect in children with sickle cell disease. Finally, an optimal imaging protocol including in vivo measurements of several critical parameters was recommended for clinical ASL studies. PMID:21613872

Wu, Wen-Chau; St Lawrence, Keith S; Licht, Daniel J; Wang, Danny J J

2010-04-01

394

Imaging spectrum of breast implant complications: mammography, ultrasound, and magnetic resonance imaging.  

PubMed

Knowledge of the various complications resulting from breast implants and the ways in which they can present radiographically is useful so that a complete evaluation can be made, thus, increasing the accuracy of diagnosis. In this article, a working knowledge of the more common breast implant types, essential to the accurate interpretation of breast implant imaging studies, is presented. In addition, imaging techniques and normal appearances of breast prostheses are described by using mammographic, sonographic, and magnetic resonance (MR) imaging. The findings of breast implant complications by using these modalities are described, including rupture, silicone extravasation, gel bleed, polyurethane breakdown, and peri-implant fluid collections. PMID:11071616

O'Toole, M; Caskey, C I

2000-10-01

395

Imaging diagnosis-magnetic resonance imaging findings of an intracranial epidural tuberculoma in a dog.  

PubMed

Magnetic resonance (MR) imaging is highly sensitive for detecting tuberculomas in human patients but the specificity of the MR imaging features is low. Misdiagnosis with intracranial neoplasia is common, especially with dural-based lesions or lesions located in the epidural space. We describe the MR imaging characteristics of an intracranial epidural tuberculoma caused by Mycobacterium tuberculosis infection in a dog. The intracranial mass and skull flat bone lysis and erosion are similar to those described in human caseating tuberculomas and can mimic intracranial neoplastic disease. PMID:22702644

de la Fuente, Cristian; Pumarola, Martí; Ródenas, Sergio; Foradada, Laia; Lloret, Albert; Pérez de Val, Bernat; Añor, Sònia

2012-06-15

396

Liver fat content determined by magnetic resonance imaging and spectroscopy.  

PubMed

Hepatic steatosis as the most prevalent liver disorder can either be related to alcoholic liver disease (ALD) or non-alcoholic fatty liver disease (NAFLD). In both conditions, hepatocytes excessively accumulate fat-containing vacuoles within their cytoplasm, which is the key histological feature. In contrast to ALD, NAFLD is commonly associated with metabolic syndrome, obesity and insulin resistance. To determine increased liver fat content, liver biopsy is currently considered the gold standard. Besides the invasive technique, various other non-invasive techniques have been developed, such as ultrasound, computed tomography (CT), magnetic resonance spectroscopy (MRS) and magnetic resonance imaging (MRI) based methods. Among these techniques, ultrasound and CT provide only qualitative information about hepatic steatosis, whereas MRS- or MRI-based methods are able to determine even small amounts of fat accurately. These non-invasive magnetic resonance techniques have already proven their great potential, especially in longitudinal and cross-sectional studies regarding various metabolic conditions and medical treatment regimens. In this review, the most common, non-invasive MRS/MRI techniques for assessment of intrahepatic lipid content are described with their inherent advantages and limitations. PMID:20355234

Springer, Fabian; Machann, Jürgen; Claussen, Claus D; Schick, Fritz; Schwenzer, Nina F

2010-04-01

397

Liver fat content determined by magnetic resonance imaging and spectroscopy  

PubMed Central

Hepatic steatosis as the most prevalent liver disorder can either be related to alcoholic liver disease (ALD) or non-alcoholic fatty liver disease (NAFLD). In both conditions, hepatocytes excessively accumulate fat-containing vacuoles within their cytoplasm, which is the key histological feature. In contrast to ALD, NAFLD is commonly associated with metabolic syndrome, obesity and insulin resistance. To determine increased liver fat content, liver biopsy is currently considered the gold standard. Besides the invasive technique, various other non-invasive techniques have been developed, such as ultrasound, computed tomography (CT), magnetic resonance spectroscopy (MRS) and magnetic resonance imaging (MRI) based methods. Among these techniques, ultrasound and CT provide only qualitative information about hepatic steatosis, whereas MRS- or MRI-based methods are able to determine even small amounts of fat accurately. These non-invasive magnetic resonance techniques have already proven their great potential, especially in longitudinal and cross-sectional studies regarding various metabolic conditions and medical treatment regimens. In this review, the most common, non-invasive MRS/MRI techniques for assessment of intrahepatic lipid content are described with their inherent advantages and limitations.

Springer, Fabian; Machann, Jurgen; Claussen, Claus D; Schick, Fritz; Schwenzer, Nina F

2010-01-01

398

Neuropathologic correlates of magnetic resonance imaging in multiple sclerosis.  

PubMed

The advent of magnetic resonance imaging (MRI) has revolutionized concepts of the pathogenesis of multiple sclerosis (MS). Magnetic resonance imaging provides the ability to delineate the evolution of the disease process over time; captured static snapshots can then be used in pathologic correlations studies. Certain patterns in the 2- or 3-dimensional MRI sphere correlate very well with similar patterns of histopathology. A multimodality approach that makes use of numerous MRI techniques can lead to significant insights into the nature of the changes in the CNS. MRI-pathology correlation studies in MS are being performed using newer MRI techniques as they become available. Such correlations and basic histopathologic studies have shown abnormalities in MS far beyond the well-documented changes in the plaque and have brought into question the dogma that MS is an initially inflammatory nondegenerative disease. This review briefly outlines technical considerations in MRI-pathology correlative studies and describes the past and current status of our ability to correlate focal and diffuse changes on the MRI with neuropathologic findings in MS patients. PMID:22892523

Moore, G R Wayne; Laule, Cornelia

2012-09-01

399

Realistic analytical phantoms for parallel magnetic resonance imaging.  

PubMed

The quantitative validation of reconstruction algorithms requires reliable data. Rasterized simulations are popular but they are tainted by an aliasing component that impacts the assessment of the performance of reconstruction. We introduce analytical simulation tools that are suited to parallel magnetic resonance imaging and allow one to build realistic phantoms. The proposed phantoms are composed of ellipses and regions with piecewise-polynomial boundaries, including spline contours, Bézier contours, and polygons. In addition, they take the channel sensitivity into account, for which we investigate two possible models. Our analytical formulations provide well-defined data in both the spatial and k-space domains. Our main contribution is the closed-form determination of the Fourier transforms that are involved. Experiments validate the proposed implementation. In a typical parallel magnetic resonance imaging reconstruction experiment, we quantify the bias in the overly optimistic results obtained with rasterized simulations-the inverse-crime situation. We provide a package that implements the different simulations and provide tools to guide the design of realistic phantoms. PMID:22049364

Guerquin-Kern, M; Lejeune, L; Pruessmann, K P; Unser, M

2011-10-28

400

Whiplash injuries can be visible by functional magnetic resonance imaging  

PubMed Central

Whiplash trauma can result in injuries that are difficult to diagnose. Diagnosis is particularly difficult in injuries to the upper segments of the cervical spine (craniocervical joint [CCJ] complex). Studies indicate that injuries in that region may be responsible for the cervicoencephalic syndrome, as evidenced by headache, balance problems, vertigo, dizziness, eye problems, tinnitus, poor concentration, sensitivity to light and pronounced fatigue. Consequently, diagnosis of lesions in the CCJ region is important. Functional magnetic resonance imaging is a radiological technique that can visualize injuries of the ligaments and the joint capsules, and accompanying pathological movement patterns. Three severely injured patients that had been extensively examined without any findings of structural lesions were diagnosed by functional magnetic resonance imaging to have injuries in the CCJ region. These injuries were confirmed at surgery, and after surgical stabilization the medical condition was highly improved. It is important to draw attention to the urgent need to diagnose lesions and dysfunction in the CCJ complex and also improve diagnostic methods.

Johansson, Bengt H

2006-01-01

401

Use of Functional Magnetic Resonance Imaging (Blood Oxygenation Level-Dependent Imaging, Diffusion Tensor Imaging and Magnetic Resonance Spectroscopy) in Brain Development Research  

Microsoft Academic Search

The development of several new magnetic resonance imaging (MRI) techniques has facilitated serial observations of the developing human brain in utero. For example, the noninvasive technique of functional MRI, which is used to study brain anatomy, function and metabolism in both humans and animals, has already enhanced our understanding of brain development and behavior relations. Currently, three main kinds of

Fei Fei Yang; Shu Guang Yuan; David T. Yew

2008-01-01

402

Histologic correlation in magnetic resonance imaging of femoral head osteonecrosis.  

PubMed

The present study was undertaken to determine whether a correlation exists between localized magnetic resonance image (MRI) signal behavior and specific histopathologic features of femoral head osteonecrosis. Contiguous, 5-mm coronal MRI sections were compared with corresponding histologic sections from six surgically excised femoral heads. After identifying specific areas of interest on the images, signal intensity was evaluated, both subjectively and objectively, and T1 and T2 relaxation times were calculated. Mean values for these data were compared among the following histologic categories: normal bone, unrepaired dead bone and marrow, unrepaired dead bone with marrow replaced by amorphous debris, and zones of repair. For each type of tissue, MRI signal intensity on T1- and intermediately T2-weighted images behaved in a distinctive fashion. Active repair tissue could be differentiated from both necrotic bone and normal bone by a tendency for the signal to increase in intensity on intermediately T2-weighted images. These findings suggest that MRI may provide a noninvasive means of quantitatively analyzing the volume and spacial distribution of repair tissue in osteonecrotic femoral heads. In clinical practice, such analysis may lead to improvements in disease staging and treatment planning. PMID:2317968

Jergesen, H E; Lang, P; Moseley, M; Genant, H K

1990-04-01

403

jSIPRO - Analysis tool for magnetic resonance spectroscopic imaging.  

PubMed

Magnetic resonance spectroscopic imaging (MRSI) involves a huge number of spectra to be processed and analyzed. Several tools enabling MRSI data processing have been developed and widely used. However, the processing programs primarily focus on sophisticated spectra processing and offer limited support for the analysis of the calculated spectroscopic maps. In this paper the jSIPRO (java Spectroscopic Imaging PROcessing) program is presented, which is a java-based graphical interface enabling post-processing, viewing, analysis and result reporting of MRSI data. Interactive graphical processing as well as protocol controlled batch processing are available in jSIPRO. jSIPRO does not contain a built-in fitting program. Instead, it makes use of fitting programs from third parties and manages the data flows. Currently, automatic spectra processing using LCModel, TARQUIN and jMRUI programs are supported. Concentration and error values, fitted spectra, metabolite images and various parametric maps can be viewed for each calculated dataset. Metabolite images can be exported in the DICOM format either for archiving purposes or for the use in neurosurgery navigation systems. PMID:23870172

Jiru, Filip; Skoch, Antonin; Wagnerova, Dita; Dezortova, Monika; Hajek, Milan

2013-07-17

404

Patient specific prostate segmentation in 3-d magnetic resonance images.  

PubMed

Accurate localization of the prostate and its surrounding tissue is essential in the treatment of prostate cancer. This paper presents a novel approach to fully automatically segment the prostate, including its seminal vesicles, within a few minutes of a magnetic resonance (MR) scan acquired without an endorectal coil. Such MR images are important in external beam radiation therapy, where using an endorectal coil is highly undesirable. The segmentation is obtained using a deformable model that is trained on-the-fly so that it is specific to the patient's scan. This case specific deformable model consists of a patient specific initialized triangulated surface and image feature model that are trained during its initialization. The image feature model is used to deform the initialized surface by template matching image features (via normalized cross-correlation) to the features of the scan. The resulting deformations are regularized over the surface via well established simple surface smoothing algorithms, which is then made anatomically valid via an optimized shape model. Mean and median Dice's similarity coefficients (DSCs) of 0.85 and 0.87 were achieved when segmenting 3T MR clinical scans of 50 patients. The median DSC result was equal to the inter-rater DSC and had a mean absolute surface error of 1.85 mm. The approach is showed to perform well near the apex and seminal vesicles of the prostate. PMID:22875243

Chandra, Shekhar S; Dowling, Jason A; Shen, Kai-Kai; Raniga, Parnesh; Pluim, Josien P W; Greer, Peter B; Salvado, Olivier; Fripp, Jurgen

2012-08-02

405

Magnetic resonance imaging of microvessels using iron-oxide nanoparticles  

NASA Astrophysics Data System (ADS)

The visualization of microstructures including blood vessels with an inner overall cross-sectional area below approximately 200 ?m remains beyond the capabilities of current clinical imaging modalities. But with magnetic resonance (MR) imaging, magnetic entities cause susceptibility artifacts in the images by disrupting the homogeneous magnetic field in a much larger scale than their actual size. As validated in this paper through simulation and in-vitro experiments, these artifacts can serve as a source of contrast, enabling microvessels with an inner diameter below the spatial resolution of any medical imaging modalities to be visualized using a clinical MR scanner. For such experiments, micron-sized agglomerations of iron-oxide (Fe3O4) nanoparticles were injected in microchannels with internal diameters of 200 and 50 ?m equivalent to a narrower artery or a larger arteriole, and down to a smaller arteriole, respectively. The results show the feasibility of the proposed method for micro-particle detection and the visualization of microvessels using a 1.5 T clinical MR scanner. It was confirmed that the method is reproducible and accurate at the sub-pixel level.

Olamaei, N.; Cheriet, F.; Martel, S.

2013-03-01

406

Active resonant subwavelength grating for scannerless range imaging sensors.  

SciTech Connect

In this late-start LDRD, we will present a design for a wavelength-agile, high-speed modulator that enables a long-term vision for the THz Scannerless Range Imaging (SRI) sensor. It takes the place of the currently-utilized SRI micro-channel plate which is limited to photocathode sensitive wavelengths (primarily in the visible and near-IR regimes). Two of Sandia's successful technologies--subwavelength diffractive optics and THz sources and detectors--are poised to extend the capabilities of the SRI sensor. The goal is to drastically broaden the SRI's sensing waveband--all the way to the THz regime--so the sensor can see through image-obscuring, scattering environments like smoke and dust. Surface properties, such as reflectivity, emissivity, and scattering roughness, vary greatly with the illuminating wavelength. Thus, objects that are difficult to image at the SRI sensor's present near-IR wavelengths may be imaged more easily at the considerably longer THz wavelengths (0.1 to 1mm). The proposed component is an active Resonant Subwavelength Grating (RSG). Sandia invested considerable effort on a passive RSG two years ago, which resulted in a highly-efficient (reflectivity greater than gold), wavelength-specific reflector. For this late-start LDRD proposal, we will transform the passive RSG design into an active laser-line reflector.

Kemme, Shanalyn A.; Nellums, Robert O.; Boye, Robert R.; Peters, David William

2006-11-01

407

Computed Tomography- and Magnetic Resonance Imaging: Guided Microtherapy.  

PubMed

This report describes techniques of computed tomography (CT) and magnetic resonance imaging (MRI) image-guided diagnosis and therapy. Fine-needle biopsy, interstitial tumor therapy, and chemical sympathectomy, as well as the treatment of chronic spinal diseases, including periradicular infiltration at irritated spinal nerve roots, percutaneous laser decompression of intervertebral disks, and intraspinal microendoscopic scar dissection after failed back surgery are described. To overcome specific drawbacks of CT application, we have evaluated technological prerequisites and feasibility of MRI guidance of interventional procedures, such as biopsy, aspiration of neoplasm, and local interstitial drug instillation. New MR-compatible needles, trocars/cannulae, endoscopes, and ancillary equipment were developed and evaluated in collaboration with industry. Sequences, study protocols, and the strategies of performing the procedure within the environment of an interventional MRI suite have been formulated. In 168 patients, 204 interventions such as aspiration biopsy, peridural corticoid injection at spinal nerve roots, intratumoral ethanol instillation, chemical sympathectomy, and percutaneous laser decompression of herniated intervertebral disks were performed successfully. CT and MRI guidance of percutaneous and microendoscopic interventions provides a reproducible and precise means of instrument control. Aside from preoperative planning of the access trajectory, instruments can be placed under CT or MRI control and the therapeutic process can be monitored. Although MRI avoids the need for ionizing radiation and provides multiplanar multislice images with excellent soft tissue contrast, the representation of instruments and the resolution is currently inferior to that achieved by CT imaging. PMID:10401142

Seibel; Melzer; Schmidt; Plabetamann

1997-06-01

408

[Magnetic resonance imaging of respiratory movement and lung function].  

PubMed

Lung function measurements are the domain of spirometry or plethysmography. These methods have proven their value in clinical practice, nevertheless, being global measurements the functional indices only describe the sum of all functional units of the lung. Impairment of only a single component of the respiratory pump or of a small part of lung parenchyma can be compensated by unaffected lung tissue. Dynamic imaging can help to detect such local changes and lead to earlier adapted therapy. Magnetic resonance imaging (MRI) seems to be perfect for this application as it is not hampered by image distortion as is projection radiography and it does not expose the patient to potentially harmful radiation like computed tomography. Unfortunately, lung parenchyma is not easy to image using MRI due to its low signal intensity. For this reason first applications of MRI in lung function measurements concentrated on the movement of the thoracic wall and the diaphragm. Recent technical advances in MRI however might allow measurements of regional dynamics of the lungs. PMID:19693620

Tetzlaff, R; Eichinger, M

2009-08-01

409

Potential of magnetic resonance for imaging the fetal heart.  

PubMed

Significant congenital heart disease (sCHD) affects 3.6 per 1000 births, and is often associated with extracardiac and chromosomal anomalies. Although early mortality has been substantially reduced and the rate of long-term survival has improved, sCHD is, after preterm birth, the second most frequent cause of neonatal infant death. The prenatal detection of cardiac and vascular abnormalities enables optimal parental counselling and perinatal management. Echocardiography (ECG) is the first-line examination and gold standard by which cardiac malformations are defined. However, adequate examination by an experienced healthcare provider with modern technical imaging equipment is required. In addition, maternal factors and the gestational age may lower the image quality. Fetal magnetic resonance imaging (MRI) has been implemented over the last several years and is already used in the clinical routine as a second-line approach to assess fetal abnormalities. MRI of the fetal heart is still not routinely performed. Nevertheless, fetal cardiac MRI has the potential to complement ultrasound in detecting cardiovascular malformations and extracardiac lesions. The present work reviews the potential of MRI to delineate the anatomy and pathologies of the fetal heart. This work also deals with the limitations and continuing developments designed to overcome the current problems in cardiac imaging, including fast fetal heart rates, the lack of ECG-gating, and the presence of fetal movements. PMID:23742821

Wielandner, Alice; Mlczoch, Elisabeth; Prayer, Daniela; Berger-Kulemann, Vanessa

2013-06-03

410

Radiation-induced optic neuropathy: A magnetic resonance imaging study  

SciTech Connect

Optic neuropathy induced by radiation is an infrequent cause of delayed visual loss that may at times be difficult to differentiate from compression of the visual pathways by recurrent neoplasm. The authors describe six patients with this disorder who experienced loss of vision 6 to 36 months after neurological surgery and radiation therapy. Of the six patients in the series, two had a pituitary adenoma and one each had a metastatic melanoma, multiple myeloma, craniopharyngioma, and lymphoepithelioma. Visual acuity in the affected eyes ranged from 20/25 to no light perception. Magnetic resonance (MR) imaging showed sellar and parasellar recurrence of both pituitary adenomas, but the intrinsic lesions of the optic nerves and optic chiasm induced by radiation were enhanced after gadolinium-diethylenetriaminepenta-acetic acid (DTPA) administration and were clearly distinguishable from the suprasellar compression of tumor. Repeated MR imaging showed spontaneous resolution of gadolinium-DTPA enhancement of the optic nerve in a patient who was initially suspected of harboring recurrence of a metastatic malignant melanoma as the cause of visual loss. The authors found the presumptive diagnosis of radiation-induced optic neuropathy facilitated by MR imaging with gadolinium-DTPA. This neuro-imaging procedure may help avert exploratory surgery in some patients with recurrent neoplasm in whom the etiology of visual loss is uncertain.

Guy, J.; Mancuso, A.; Beck, R.; Moster, M.L.; Sedwick, L.A.; Quisling, R.G.; Rhoton, A.L. Jr.; Protzko, E.E.; Schiffman, J. (Univ. of Florida, Gainesville (USA))

1991-03-01

411

Prenatal diagnosis of hemifacial microsomia by magnetic resonance imaging.  

PubMed

We present a case of hemifacial microsomia, first detected by prenatal sonography and confirmed by ultrafast magnetic resonance (MR) imaging. A 26-year-old patient was referred to our hospital at 20 weeks of gestation because of unilateral right-sided ventriculomegaly and of a possible ventriculoseptal defect (VSD). Our sonographic examination suggested a right orbital hypoplasia and a hemiatrophy of the nose. The ultrafast T2-weighted single-shot fast-spin echo MR imaging, demonstrated a right ear hypoplasia (microtia), a right orbital hypoplasia, and a right renal hypoplasia. Epibulbar dermoid or conjunctival lipodermoid were not recognized. The fetus was prenatally diagnosed as hemifacial microsomia. Termination of pregnancy was performed at 21 weeks gestation, and a male baby weighing 342g was stillborn. The baby showed facial asymmetry, including hemiatrophy of the right nose, and right ear hypoplasia. Autopsy revealed a 2mm area of VSD, agenesis of the right kidney and ureter, pancreatic and renal aberration into right adrenal gland, thymus hypoplasia and an unfixed ascending colon without intestinal malrotation. To the best of our knowledge, this is the first report of prenatal diagnosis for hemifacial microsomia using fetal MR imaging. In our case, fetal MR imaging has evolved into a powerful diagnostic tool, for the accurate prenatal diagnosis. PMID:15841618

Hattori, Yoshihisa; Tanaka, Mamoru; Matsumoto, Tadashi; Uehara, Katsuhiko; Ueno, Kazunori; Miwegishi, Kazuhiro; Ishimoto, Hitoshi; Miyakoshi, Kei; Yoshimura, Yasunori

2005-01-01

412

Magnetic resonance imaging of clays: swelling, sedimentation, dissolution  

NASA Astrophysics Data System (ADS)

While most magnetic resonance imaging (MRI) applications concern medical research, there is a rapidly increasing number of MRI studies in the field of environmental science and technology. In this presentation, MRI will be introduced from the latter perspective. While many processes in these areas are similar to those addressed in medical applications of MRI, parameters and experimental implementations are often quite different and, in many respects, far more demanding. This hinders direct transfer of existing methods developed for biomedical research, especially when facing the challenging task of obtaining spatially resolved quantitative information. In MRI investigation of soils, clays, and rocks, mainly water signal is detected, similarly to MRI of biological and medical samples. However, a strong variation of water mobility and a wide spread of water spin relaxation properties in these materials make it difficult to use standard MRI approaches. Other significant limitations can be identified as following: T2 relaxation and probe dead time effects; molecular diffusion artifacts; varying dielectric losses and induced currents in conductive samples; limited dynamic range; blurring artifacts accompanying drive for increasing sensitivity and/or imaging speed. Despite these limitations, by combining MRI techniques developed for solid and liquid states and using independent information on relaxation properties of water, interacting with the material of interest, true images of distributions of both water, material and molecular properties in a wide range of concentrations can be obtained. Examples of MRI application will be given in the areas of soil and mineral research where understanding water transport and erosion processes is one of the key challenges. Efforts in developing and adapting MRI approaches to study these kinds of systems will be outlined as well. Extensive studies of clay/water interaction have been carried out in order to provide a quantitative measure of clay distribution in extended samples during different physical processes such as swelling, dissolution, and sedimentation on the time scale from minutes to years [1-3]. To characterize the state of colloids that form after/during clay swelling the water self-diffusion coefficient was measured on a spatially resolved manner. Both natural clays and purified and ion-exchanged montmorillonite clays were investigated. The primary variables were clay composition and water ionic strength. These results have a significant impact for engineering barriers for storage of spent nuclear fuel where clay erosion by low salinity water must be addressed. Presented methods were developed under the motivation of using bentonite clays as a buffer medium to build in-ground barriers for the encapsulation of radioactive waste. Nevertheless, the same approaches can be found suitable in other applications in soil and environmental science to study other types of materials as they swell, dissolve, erode, or sediment. Acknowledgements: This work has been supported by the Swedish Nuclear Fuel and Waste Management Co (SKB) and the Swedish Research Council VR. [1] N. Nestle, T. Baumann, R. Niessner, Magnetic resonance imaging in environmental science. Environ. Sci. Techn. 36 154A (2002). [2] S. V. Dvinskikh, K. Szutkowski, I. Furó. MRI profiles over a very wide concentration ranges: application to swelling of a bentonite clay. J. Magn. Reson. 198 146 (2009). [3] S. V. Dvinskikh, I. Furó. Magnetic resonance imaging and nuclear magnetic resonance investigations of bentonite systems. Technical Report, TR-09-27, SKB (2009), www.skb.se.

Dvinskikh, Sergey; Furo, Istvan

2010-05-01

413

Magnetic resonance cholangiopancreatography image enhancement for automatic disease detection  

PubMed Central

AIM: To sufficiently improve magnetic resonance cholangiopancreatography (MRCP) quality to enable reliable computer-aided diagnosis (CAD). METHODS: A set of image enhancement strategies that included filters (i.e. Gaussian, median, Wiener and Perona-Malik), wavelets (i.e. contourlet, ridgelet and a non-orthogonal noise compensation implementation), graph-cut approaches using lazy-snapping and Phase Unwrapping MAxflow, and binary thresholding using a fixed threshold and dynamic thresholding via histogram analysis were implemented to overcome the adverse characteristics of MRCP images such as acquisition noise, artifacts, partial volume effect and large inter- and intra-patient image intensity variations, all of which pose problems in application development. Subjective evaluation of several popular pre-processing techniques was undertaken to improve the quality of the 2D MRCP images and enhance the detection of the significant biliary structures within them, with the purpose of biliary disease detection. RESULTS: The results varied as expected since each algorithm capitalized on different characteristics of the images. For denoising, the Perona-Malik and contourlet approaches were found to be the most suitable. In terms of extraction of the significant biliary structures and removal of background, the thresholding approaches performed well. The interactive scheme performed the best, especially by using the strengths of the graph-cut algorithm enhanced by user-friendly lazy-snapping for foreground and background marker selection. CONCLUSION: Tests show promising results for some techniques, but not others, as viable image enhancement modules for automatic CAD systems for biliary and liver diseases.

Logeswaran, Rajasvaran

2010-01-01

414

Grid Computing Application for Brain Magnetic Resonance Image Processing  

NASA Astrophysics Data System (ADS)

This work emphasizes the use of grid computing and web technology for automatic post-processing of brain magnetic resonance images (MRI) in the context of neuropsychiatric (Alzheimer's disease) research. Post-acquisition image processing is achieved through the interconnection of several individual processes into pipelines. Each process has input and output data ports, options and execution parameters, and performs single tasks such as: a) extracting individual image attributes (e.g. dimensions, orientation, center of mass), b) performing image transformations (e.g. scaling, rotation, skewing, intensity standardization, linear and non-linear registration), c) performing image statistical analyses, and d) producing the necessary quality control images and/or files for user review. The pipelines are built to perform specific sequences of tasks on the alphanumeric data and MRIs contained in our database. The web application is coded in PHP and allows the creation of scripts to create, store and execute pipelines and their instances either on our local cluster or on high-performance computing platforms. To run an instance on an external cluster, the web application opens a communication tunnel through which it copies the necessary files, submits the execution commands and collects the results. We present result on system tests for the processing of a set of 821 brain MRIs from the Alzheimer's Disease Neuroimaging Initiative study via a nonlinear registration pipeline composed of 10 processes. Our results show successful execution on both local and external clusters, and a 4-fold increase in performance if using the external cluster. However, the latter's performance does not scale linearly as queue waiting times and execution overhead increase with the number of tasks to be executed.

Valdivia, F.; Crépeault, B.; Duchesne, S.

2012-02-01

415

Enhancing magnetic resonance imaging tumor detection with fluorescence intensity and lifetime imaging  

NASA Astrophysics Data System (ADS)

Early detection is important for many solid cancers but the images provided by ultrasound, magnetic resonance imaging (MRI), and computed tomography applied alone or together, are often not sufficient for decisive early screening/diagnosis. We demonstrate that MRI augmented with fluorescence intensity (FI) substantially improves detection. Early stage murine pancreatic tumors that could not be identified by blinded, skilled observers using MRI alone, were easily identified with MRI along with FI images acquired with photomultiplier tube detection and offset laser scanning. Moreover, we show that fluorescence lifetime (FLT) imaging enables positive identification of the labeling fluorophore and discriminates it from surrounding tissue autofluorescence. Our data suggest combined-modality imaging with MRI, FI, and FLT can be used to screen and diagnose early tumors.

Erten, Ahmet; Hall, David; Hoh, Carl; Tran Cao, Hop S.; Kaushal, Sharmeela; Esener, Sadik; Hoffman, Robert M.; Bouvet, Michael; Chen, James; Kesari, Santosh; Makale, Milan

2010-11-01

416

Merging the computed tomography and magnetic resonance imaging images for the visualization of temporomandibular joint disk.  

PubMed

Computed tomography (CT) depicts intricate bony details well, whereas magnetic resonance imaging (MRI) offers excellent contrast to the anatomy of soft tissues. This technical report offers a method to merge the CT and MRI images using Photoshop software and yield hybrid images that combine the key features of both CT and MRI. In this hybrid image, the temporomandibular joint (TMJ) disk was clearly displayed, and the relationship between the TMJ disk and surrounding skeleton structures, including glenoid fossa and condyle, also was finely demonstrated. Although the merging process is not absolutely accurate, the method presented in this article can be applied as a supplementary way to help the physicians to read the image of TMJ in an even better fashion and also may offer a useful method to help the junior physicians to quickly identify the TMJ disk. PMID:23172513

Dai, Jiewen; Dong, Yuefu; Shen, Steve Guofang

2012-11-01

417

Magnetic resonance image analysis by information theoretic criteria and stochastic site models  

Microsoft Academic Search

Abstract, Quantitative analysis of magnetic resonance (MR) images is a powerful tool for image-guided diagnosis, monitoring, and intervention. The major tasks involve tissue quantification and image segmentation where both the pixel and context images are considered. To extract clinically useful information from images that might be lacking in prior knowledge, we introduce an unsu-pervised tissue characterization algorithm that is both

Yue Wang; Tülay Adali; Jianhua Xuan; Zsolt Szabo

2001-01-01

418

Advanced Theory of Driven Birdcage Resonator with Losses for Biomedical Magnetic Resonance Imaging and Spectroscopy  

PubMed Central

A complete time-dependent physics theory of symmetric unperturbed driven Hybrid Birdcage resonator was developed for general application. In particular, the theory can be applied for RF coil engineering, computer simulations of coil-sample interaction, etc. Explicit time dependence is evaluated for different forms of driving voltage. The major steps of the solution development are shown and appropriate explanations are given. Green’s functions and spectral density formula were developed for any form of periodic driving voltage. The concept of distributed power losses based on transmission line theory is developed for evaluation of local losses of a coil. Three major types of power losses are estimated as equivalent series resistances in the circuit of the Birdcage resonator. Values of generated resistances in Legs and End-Rings are estimated. An application of the theory is shown for many practical cases. Experimental curve of B1 field polarization dependence is measured for eight-sections Birdcage coil. It was shown, that the steady-state driven resonance frequencies do not depend on damping factor unlike the free oscillation (transient) frequencies. An equivalent active resistance is generated due to interaction of RF electromagnetic field with a sample. Resistance of the conductor (enhanced by skin effect), Eddy currents and dielectric losses are the major types of losses which contribute to the values of generated resistances. A biomedical sample for magnetic resonance imaging and spectroscopy is the source of the both Eddy current and dielectric losses of a coil. As demonstrated by the theory, Eddy currents losses is the major effect of coil shielding.

Novikov, Alexander

2010-01-01

419

Medical image diagnostics based on computer-aided flow analysis using magnetic resonance images.  

PubMed

Most of the cardiac abnormalities have an implication on hemodynamics and affect cardiovascular health. Diagnostic imaging modalities such as computed tomography and magnetic resonance imaging provide excellent anatomical information on myocardial structures, but fail to show the cardiac flow and detect heart defects in vivo condition. The computerized technique for fluid motion estimation by pixel intensity tracking based on magnetic resonance signals represents a promising technique for functional assessment of cardiovascular disease, as it can provide functional information of the heart in addition to analysis of its anatomy. Cardiovascular flow characteristics can be measured in both normal controls and patients with cardiac abnormalities such as atrial septal defect, thus, enabling identification of the underlying causes of these flow phenomena. This review paper focuses on an overview of a flow analysis scheme based on computer-aided evaluation of magnetic resonance intensity images, in comparison with other commonly used medical imaging modalities. Details of the proposed technique are provided with validations being conducted at selected abnormal cardiovascular patients. It is expected that this new technique can potentially extend applications for characterizing cardiovascular defects and their hemodynamic behavior. PMID:22575846

Wong, Kelvin K L; Sun, Zhonghua; Tu, Jiyuan; Worthley, Stephen G; Mazumdar, Jagannath; Abbott, Derek

2012-05-08

420

Magnetic resonance velocimetry: applications of magnetic resonance imaging in the measurement of fluid motion  

NASA Astrophysics Data System (ADS)

Magnetic resonance velocimetry (MRV) is a non-invasive technique capable of measuring the three-component mean velocity field in complex three-dimensional geometries with either steady or periodic boundary conditions. The technique is based on the phenomenon of nuclear magnetic resonance (NMR) and works in conventional magnetic resonance imaging (MRI) magnets used for clinical imaging. Velocities can be measured along single lines, in planes, or in full 3D volumes with sub-millimeter resolution. No optical access or flow markers are required so measurements can be obtained in clear or opaque MR compatible flow models and fluids. Because of its versatility and the widespread availability of MRI scanners, MRV is seeing increasing application in both biological and engineering flows. MRV measurements typically image the hydrogen protons in liquid flows due to the relatively high intrinsic signal-to-noise ratio (SNR). Nonetheless, lower SNR applications such as fluorine gas flows are beginning to appear in the literature. MRV can be used in laminar and turbulent flows, single and multiphase flows, and even non-isothermal flows. In addition to measuring mean velocity, MRI techniques can measure turbulent velocities, diffusion coefficients and tensors, and temperature. This review surveys recent developments in MRI measurement techniques primarily in turbulent liquid and gas flows. A general description of MRV provides background for a discussion of its accuracy and limitations. Techniques for decreasing scan time such as parallel imaging and partial k-space sampling are discussed. MRV applications are reviewed in the areas of physiology, biology, and engineering. Included are measurements of arterial blood flow and gas flow in human lungs. Featured engineering applications include the scanning of turbulent flows in complex geometries for CFD validation, the rapid iterative design of complex internal flow passages, velocity and phase composition measurements in multiphase flows, and the scanning of flows through porous media. Temperature measurements using MR thermometry are discussed. Finally, post-processing methods are covered to demonstrate the utility of MRV data for calculating relative pressure fields and wall shear stresses.

Elkins, Christopher J.; Alley, Marcus T.

2007-12-01

421

Bacteria tracking by in vivo magnetic resonance imaging  

PubMed Central

Background Different non-invasive real-time imaging techniques have been developed over the last decades to study bacterial pathogenic mechanisms in mouse models by following infections over a time course. In vivo investigations of bacterial infections previously relied mostly on bioluminescence imaging (BLI), which is able to localize metabolically active bacteria, but provides no data on the status of the involved organs in the infected host organism. In this study we established an in vivo imaging platform by magnetic resonance imaging (MRI) for tracking bacteria in mouse models of infection to study infection biology of clinically relevant bacteria. Results We have developed a method to label Gram-positive and Gram-negative bacteria with iron oxide nano particles and detected and pursued these with MRI. The key step for successful labeling was to manipulate the bacterial surface charge by producing electro-competent cells enabling charge interactions between the iron particles and the cell wall. Different particle sizes and coatings were tested for their ability to attach to the cell wall and possible labeling mechanisms were elaborated by comparing Gram-positive and -negative bacterial characteristics. With 5-nm citrate-coated particles an iron load of 0.015 ± 0.002 pg Fe/bacterial cell was achieved for Staphylococcus aureus. In both a subcutaneous and a systemic infection model induced by iron-labeled S. aureus bacteria, high resolution MR images allowed for bacterial tracking and provided information on the morphology of organs and the inflammatory response. Conclusion Labeled with iron oxide particles, in vivo detection of small S. aureus colonies in infection models is feasible by MRI and provides a versatile tool to follow bacterial infections in vivo. The established cell labeling strategy can easily be transferred to other bacterial species and thus provides a conceptual advance in the field of molecular MRI.

2013-01-01

422

Method for Cortical Bone Structural Analysis from Magnetic Resonance Images  

PubMed Central

Rationale Quantitative evaluation of cortical bone architecture as a means to assess bone strength is typically accomplished on the basis of images obtained by dual-energy X-ray absorptiometry (DXA) or computed tomography (CT). Magnetic resonance imaging (MRI) has potential advantages for this task in that it allows imaging in arbitrary scan planes at high spatial resolution. However, several hurdles have to be overcome in order to make this approach practical, including resolution of issues related to nonlinear receive coil sensitivity, variations in marrow composition and the presence periosteal isointense tissues which all complicate segmentation. Objectives To develop MR acquisition and analysis methods optimized for detection of cortical boundaries in complex geometries such as the femoral neck. Materials and Methods Cortical boundary detection is achieved by radially tracing intensity profiles that intersect the bone’s periosteal and endosteal boundary. The profiles are subsequently normalized to the intensity of the marrow signal, processed with morphologic image operators and binarized. The resulting boundaries are then mapped back onto the spatial image and erroneous boundary points removed. From the detected cortical boundaries cortical cross-sectional area and thickness are computed. The method was evaluated on cortical bone specimens and human volunteers on the basis of high-resolution images acquired at 1.5 Tesla field strength. To assess whether the method is sensitive to detect the expected dependencies of cortical parameters in weight-bearing bone on overall habitus, ten women ages 46–73 years (mean 56 years) underwent the cortical imaging protocol in the proximal femur and the results were compared with DXA BMD parameters of the hip and spine. Results Reproducibility was on the order of 2%. Double oblique images of the femoral neck in the ten women studied showed cortical cross-sectional area to correlate strongly with height (r = 0.88, p = 0.0008) while cortical diameter versus age approached significance (r = 0.61, p = 0.06). Measurements in specimens of some cortical parameters indicated a resolution dependence. It is to be noted, however, that parameter rank remained constant across all specimens studied. Conclusion The data suggest the new method to be robust and applicable on standard clinical MR scanners at arbitrary anatomic locations to yield clinically meaningful quantitative results.

Gomberg, Bryon R.; Saha, Punam K.; Wehrli, Felix W.

2005-01-01

423

Superparamagnetic nanoparticles for enhanced magnetic resonance and multimodal imaging  

NASA Astrophysics Data System (ADS)

Magnetic resonance imaging (MRI) is a powerful tool for noninvasive tomographic imaging of biological systems with high spatial and temporal resolution. Superparamagnetic (SPM) nanoparticles have emerged as highly effective MR contrast agents due to their biocompatibility, ease of surface modification and magnetic properties. Conventional nanoparticle contrast agents suffer from difficult synthetic reproducibility, polydisperse sizes and weak magnetism. Numerous synthetic techniques and nanoparticle formulations have been developed to overcome these barriers. However, there are still major limitations in the development of new nanoparticle-based probes for MR and multimodal imaging including low signal amplification and absence of biochemical reporters. To address these issues, a set of multimodal (T2/optical) and dual contrast (T1/T2) nanoparticle probes has been developed. Their unique magnetic properties and imaging capabilities were thoroughly explored. An enzyme-activatable contrast agent is currently being developed as an innovative means for early in vivo detection of cancer at the cellular level. Multimodal probes function by combining the strengths of multiple imaging techniques into a single agent. Co-registration of data obtained by multiple imaging modalities validates the data, enhancing its quality and reliability. A series of T2/optical probes were successfully synthesized by attachment of a fluorescent dye to the surface of different types of nanoparticles. The multimodal nanoparticles generated sufficient MR and fluorescence signal to image transplanted islets in vivo. Dual contrast T1/T2 imaging probes were designed to overcome disadvantages inherent in the individual T1 and T2 components. A class of T1/T2 agents was developed consisting of a gadolinium (III) complex (DTPA chelate or DO3A macrocycle) conjugated to a biocompatible silica-coated metal oxide nanoparticle through a disulfide linker. The disulfide linker has the ability to be reduced in vivo by glutathione, releasing large payloads of signal-enhancing T1 probes into the surrounding environment. Optimization of the agent occurred over three sequential generations, with each generation addressing a new challenge. The result was a T2 nanoparticle containing high levels of conjugated T1 complex demonstrating enhanced MR relaxation properties. The probes created here have the potential to play a key role in the advancement of nanoparticle-based agents in biomedical MRI applications.

Sikma, Elise Ann Schultz

424

Magnetic resonance imaging (MRI) and relaxation time mapping of concrete  

NASA Astrophysics Data System (ADS)

The use of Magnetic Resonance Imaging (MRI) of water in concrete is presented. This thesis will approach the problem of MR imaging of concrete by attempting to design new methods, suited to concrete materials, rather than attempting to force the material to suit the method. A number of techniques were developed, which allow the spatial observation of water in concrete in up to three dimensions, and permits the determination of space resolved moisture content, as well as local NMR relaxation times. These methods are all based on the Single-Point Imaging (SPI) method. The development of these new methods will be described, and the techniques validated using phantom studies. The study of one-dimensional moisture transport in drying concrete was performed using SPI. This work examined the effect of initial mixture proportions and hydration time on the drying behaviour of concrete, over a period of three months. Studies of drying concrete were also performed using spatial mapping of the spin-lattice (T1) and effective spin-spin (T2*) relaxation times, thereby permitting the observation of changes in the water occupied pore surface-to-volume ratio (S/V) as a function of drying. Results of this work demonstrated changes in the S/V due to drying, hydration and drying induced microcracking. Three-dimensional MRI of concrete was performed using SPRITE (Single-Point Ramped Imaging with T1 Enhancement) and turboSPI (turbo Single Point Imaging). While SPRITE allows for weighting of MR images using T 1 and T2*, turboSPI allows T2 weighting of the resulting images. Using relaxation weighting it was shown to be possible to discriminate between water contained within a hydrated cement matrix, and water in highly porous aggregates, used to produce low-density concrete. Three dimensional experiments performed using SPRITE and turboSPI examined the role of self-dessication, drying, initial aggregate saturation and initial mixture conditions on the transport of moisture between porous aggregates and the hydrated matrix. The results demonstrate that water is both added and removed from the aggregates, depending upon the physical conditions. The images also appear to show an influx of cement products into cracks in the solid aggregate. (Abstract shortened by UMI.)

Beyea, Steven Donald

2001-07-01

425

Nanoparticle Pharmacokinetic Profiling in vivo using Magnetic Resonance Imaging  

PubMed Central

Contrast agents targeted to molecular markers of disease are currently being developed with the goal of identifying disease early and evaluating treatment effectiveness using non-invasive imaging modalities such as MRI. Pharmacokinetic profiling of the binding of targeted contrast agents, while theoretically possible with MRI, has thus far only been demonstrated with more sensitive imaging techniques. Paramagnetic liquid perfluorocarbon nanoparticles were formulated to target ?v?3-integrins associated with early atherosclerosis in cholesterol-fed rabbits in order to produce a measurable signal increase on magnetic resonance images after binding. In this work, we combine quantitative information of the in vivo binding of this agent over time obtained via MRI with blood sampling to derive pharmacokinetic parameters using simultaneous and individual fitting of the data to a three compartment model. A doubling of tissue exposure (or area under the curve) is obtained with targeted as compared to control nanoparticles, and key parameter differences are discovered that may aid in development of models for targeted drug delivery.

Neubauer, Anne M.; Sim, Hoon; Winter, Patrick M.; Caruthers, Shelton D.; Williams, Todd A.; Robertson, J. David; Sept, David; Lanza, Gregory M.; Wickline, Samuel A.

2008-01-01

426

Magnetic resonance imaging of the wrist: bone and cartilage injury.  

PubMed

Magnetic resonance imaging (MRI) is particularly useful for imaging the wrist due to its superior soft tissue contrast and ability to detect subtle bone marrow changes and occult fractures. A high field (1.5T or greater) strength, dedicated wrist coil, and high in-plane and through-plane resolution must be utilized to successfully visualize the relatively thin cartilage of the wrist. MRI can be used to detect occult carpal bone fractures, identify complications following scaphoid fractures, and assess for avascular necrosis in the setting in Kienböck's and Preiser's disease. MRI is useful to identify secondary soft tissue and chondral pathology in impaction/impingement syndromes. The use of an intermediate-echo time fast spin echo sequence allows for accurate assessment of articular cartilage, allowing evaluation of chondral wear in the setting of primary osteoarthritis and posttraumatic degenerative arthrosis. MRI is the most sensitive imaging modality for the detection of early inflammatory arthropathies and can detect synovitis, bone marrow edema, and early erosions in the setting of negative radiographs. PMID:23606139

Hayter, Catherine L; Gold, Stephanie L; Potter, Hollis G

2013-05-01

427

Magnetic Resonance Sialography Findings of Submandibular Ducts Imaging  

PubMed Central

Purpose. We aimed to assess the problem solving capability of magnetic resonance sialography (MR sialography), a noninvasive method for imaging submandibular gland ducts and determining duct-related pathologies, by comparing diseased and healthy cases. Materials and Methods. We conducted radiological assessment on a total of 60 submandibular glands (mean age 44.7) in 20 cases and 10 volunteers. MR sialography examinations were conducted with single-shot fast spin-echo sequence by using a surface coil placed on the submandibular gland. Each gland was evaluated in terms of the length, width and stricture of the main duct, as well as the difference between the intraparenchymal duct width, and the main duct width. Statistical analysis was performed. Results. In the MR sialography the primary duct mean length was determined as 51?mm (40–57?mm) in all submandibular glands. On the MR sialography imaging, the visualization ratio of the ductal system of submandibular gland was evaluated in the cases and volunteers. Conclusion. MR sialography is an effective and a noninvasive method in imaging submandibular gland ducts, demonstrating the presence, location and degree of stricture/dilatation, and elucidating the disease etiology.

Karaca Erdogan, Nezahat; Altay, Canan; Ozenler, Nesibe; Bozkurt, Tugba; Uluc, Engin; Dirim Mete, Berna; Ozdemir, Ismail

2013-01-01

428

A magnetic-resonance-imaging-compatible remote catheter navigation system.  

PubMed

A remote catheter navigation system compatible with magnetic resonance imaging (MRI) has been developed to facilitate MRI-guided catheterization procedures. The interventionalist's conventional motions (axial motion and rotation) on an input catheter - acting as the master - are measured by a pair of optical encoders, and a custom embedded system relays the motions to a pair of ultrasonic motors. The ultrasonic motors drive the patient catheter (slave) within the MRI scanner, replicating the motion of the input catheter. The performance of the remote catheter navigation system was evaluated in terms of accuracy and delay of motion replication outside and within the bore of the magnet. While inside the scanner bore, motion accuracy was characterized during the acquisition of frequently used imaging sequences, including real-time gradient echo. The effect of the catheter navigation system on image signal-to-noise ratio (SNR) was also evaluated. The results show that the master-slave system has a maximum time delay of 41 ± 21 ms in replicating motion; an absolute value error of 2 ± 2° was measured for radial catheter motion replication over 360° and 1.0 ± 0.8 mm in axial catheter motion replication over 100 mm of travel. The worst-case SNR drop was observed to be 2.5%. PMID:23192485

Tavallaei, Mohammad Ali; Thakur, Yogesh; Haider, Syed; Drangova, Maria

2012-11-21

429

Fetal Hippocampal Development: Analysis by Magnetic Resonance Imaging Volumetry  

PubMed Central

The hippocampal formation plays an important role in learning and memory, however data on its development in utero in humans is limited. This study was performed to evaluate hippocampal development in healthy fetuses using 3D reconstructed magnetic resonance imaging (MRI). A cohort of 20 healthy pregnant women underwent prenatal MRI at a median gestational age of 24.9 weeks (range 21.3-31.9 weeks); 6 of the women also had a second fetal MRI performed at a 6 week interval. Routine 2D ultrafast T2-weighted images were used to reconstruct a 3D volume image, which was then used to manually segment the right and left hippocampi. Total hippocampal volume was calculated for each subject and compared against gestational age. There was a linear increase in total hippocampal volume with increasing gestational age (P<0.001). For subjects scanned twice, there was an increase in hippocampal size on the second fetal MRI (P=0.0004). This represents the first volumetric study of fetal hippocampal development in vivo. This normative volumetric data will be helpful for future comparison studies of suspected developmental abnormalities of hippocampal structure and function.

Jacob, Francois Dominique; Habas, Piotr; Kim, Kio; Corbett-Detig, James; Xu, Duan; Studholme, Colin; Glenn, Orit A.

2011-01-01

430

Magnetic resonance imaging in acute stroke: clinical perspective.  

PubMed

The efficacy of intravenous (i.v.) and intra-arterial (i.a.) thrombolysis for hyperacute stroke has made "brain attack" a treatable emergency. The addition of ultrafast magnetic resonance imaging (MRI) to acute stroke investigation has both increased our knowledge of acute stroke pathophysiology and brought a tool to study how to best select patients for thrombolytic therapy. MR offers the three essential components: vascular lesion identification, delineation of injured brain tissue, and map of ischemic brain. MR angiography can demonstrate the site of major cerebral artery occlusion, providing a means to screen for i.a. thrombolysis. Diffusion-weighted imaging (DWI) is capable of showing acute ischemic injury within minutes of symptom onset. Perfusion-weighted imaging (PWI) shows the total area of acute ischemia, more accurately reflecting the extent of neurological dysfunction. Combining DWI and PWI immediately gives information that bears on how much tissue is injured (DWI) and how much tissue is functionally inactive but still viable (ischemic on PWI but still normal on DWI). A number of important questions remain, but current knowledge of natural history of stroke with MRI has provided a framework for comparing new therapeutic interventions. Ideally, patient treatment in the future will be tailored not to a fixed time window but to the physiological state of the ischemic tissue as defined by MRI. PMID:11142624

Oliveira-Filho, J; Koroshetz, W J

2000-10-01

431

Incidental Bartholin Gland Cysts Identified on Pelvic Magnetic Resonance Imaging  

PubMed Central

Objective To estimate the prevalence of Bartholin gland cysts in asymptomatic women serving as control participants who underwent pelvic magnetic resonance imaging (MRI) as part of research studies. The secondary aim was to investigate potential demographic characteristics associated with Bartholin gland cysts. Methods Pelvic MRIs from 430 control participants enrolled in five research projects were evaluated. All images were evaluated by at least two authors. The presence, laterality, and size of Bartholin gland cysts were recorded. Demographic information for each participant was obtained at the time of enrollment in the respective parent study. Results Approximately 3% of the participants had visible Bartholin gland cysts in MRI scans. Fifty-percent of the cysts were identified on the right side, 42.9% were seen on the left side, and 7.1% were bilateral. The cysts were, on average, 1.3 × 1.2 × 1.3 cm, with dimensions ranging from 0.5 – 2.7 cm. There were no demographic differences between women with and without visible Bartholin gland cysts. Conclusion Bartholin gland cysts occur in 3% of adult women. The cysts affect women of broad ranges of age and parity. Women with visible Bartholin gland cysts are demographically similar to women without cysts on pelvic imaging.

Berger, Mitchell B.; Betschart, Cornelia; Khandwala, Nikhila; DeLancey, John O.; Haefner, Hope K.

2012-01-01

432

Health Technology Case Study 27: Nuclear Magnetic Resonance Imaging Technology. A Clinical, Industrial, and Policy Analysis.  

National Technical Information Service (NTIS)

Nuclear magnetic resonance (NMR) imaging is an exciting new diagnostic imaging modality that has captured the interest of the medical profession for a number of reasons. It employs radiowaves and magnetic fields rather than ionizing radiation, thus elimin...

A. B. Cohen E. P. Steinberg

1984-01-01

433

Pulse Coupled Neural Networks for the Segmentation of Magnetic Resonance Brain Images.  

National Technical Information Service (NTIS)

This research develops an automated method for segmenting Magnetic Resonance (MR) brain images based on Pulse Coupled Neural Networks (PCNN). The method developed and presented uses a PCNN to both filter and segment MR brain images. The technique begins b...

S. L. Abrahamson

1996-01-01

434

The Accuracy of Magnetic Resonance Imaging and Magnetic Resonance Arthrogram Versus Arthroscopy in the Diagnosis of Subscapularis Tendon Injury  

Microsoft Academic Search

PurposeThe main purpose of this study was to evaluate the accuracy of preoperative magnetic resonance imaging (MRI) in detecting subscapularis tears identified during the gold standard of arthroscopy and to determine if MRI can reliably predict which patients have subscapularis tears. A second purpose was to determine whether MR arthrograms could better identify a subscapularis tear than conventional MR imaging.

Abdullah Foad; Coen A. Wijdicks

435

Fusion of color Doppler and magnetic resonance images of the heart.  

PubMed

This study was designed to establish and analyze color Doppler and magnetic resonance fusion images of the heart, an approach for simultaneous testing of cardiac pathological alterations, performance, and hemodynamics. Ten volunteers were tested in this study. The echocardiographic images were produced by Philips IE33 system and the magnetic resonance images were generated from Philips 3.0-T system. The fusion application was implemented on MATLAB platform utilizing image processing technology. The fusion image was generated from the following steps: (1) color Doppler blood flow segmentation, (2) image registration of color Doppler and magnetic resonance imaging, and (3) image fusion of different image types. The fusion images of color Doppler blood flow and magnetic resonance images were implemented by MATLAB programming in our laboratory. Images and videos were displayed and saved as AVI and JPG. The present study shows that the method we have developed can be used to fuse color flow Doppler and magnetic resonance images of the heart. We believe that the method has the potential to: fill in information missing from the ultrasound or MRI alone, show structures outside the field of view of the ultrasound through MR imaging, and obtain complementary information through the fusion of the two imaging methods (structure from MRI and function from ultrasound). PMID:21656081

Wang, Chao; Chen, Ming; Zhao, Jiang-Min; Liu, Yi

2011-12-01

436

Combining magnetic resonance imaging and ultrawideband radar: a new concept for multimodal biomedical imaging.  

PubMed

Due to the recent advances in ultrawideband (UWB) radar technologies, there has been widespread interest in the medical applications of this technology. We propose the multimodal combination of magnetic resonance (MR) and UWB radar for improved functional diagnosis and imaging. A demonstrator was established to prove the feasibility of the simultaneous acquisition of physiological events by magnetic resonance imaging and UWB radar. Furthermore, first in vivo experiments have been carried out, utilizing this new approach. Correlating the reconstructed UWB signals with physiological signatures acquired by simultaneous MR measurements, representing respiratory and myocardial displacements, gave encouraging results which can be improved by optimization of the MR data acquisition technique or the use of UWB antenna arrays to localize the motion in a focused area. PMID:19191450

Thiel, F; Hein, M; Schwarz, U; Sachs, J; Seifert, F

2009-01-01

437

Concurrent multiscale imaging with magnetic resonance imaging and optical coherence tomography  

NASA Astrophysics Data System (ADS)

We develop a novel platform based on a tele-operated robot to perform high-resolution optical coherence tomography (OCT) imaging under continuous large field-of-view magnetic resonance imaging (MRI) guidance. Intra-operative MRI (iMRI) is a promising guidance tool for high-precision surgery, but it may not have sufficient resolution or contrast to visualize certain small targets. To address these limitations, we develop an MRI-compatible OCT needle probe, which is capable of providing microscale tissue architecture in conjunction with macroscale MRI tissue morphology in real time. Coregistered MRI/OCT images on ex vivo chicken breast and human brain tissues demonstrate that the complementary imaging scales and contrast mechanisms have great potential to improve the efficiency and the accuracy of iMRI procedure.

Liang, Chia-Pin; Yang, Bo; Kim, Il Kyoon; Makris, George; Desai, Jaydev P.; Gullapalli, Rao P.; Chen, Yu

2013-04-01

438

Concurrent multiscale imaging with magnetic resonance imaging and optical coherence tomography.  

PubMed

We develop a novel platform based on a tele-operated robot to perform high-resolution optical coherence tomography (OCT) imaging under continuous large field-of-view magnetic resonance imaging (MRI) guidance. Intra-operative MRI (iMRI) is a promising guidance tool for high-precision surgery, but it may not have sufficient resolution or contrast to visualize certain small targets. To address these limitations, we develop an MRI-compatible OCT needle probe, which is capable of providing microscale tissue architecture in conjunction with macroscale MRI tissue morphology in real time. Coregistered MRI/OCT images on ex vivo chicken breast and human brain tissues demonstrate that the complementary imaging scales and contrast mechanisms have great potential to improve the efficiency and the accuracy of iMRI procedure. PMID:23609326

Liang, Chia-Pin; Yang, Bo; Kim, Il Kyoon; Makris, George; Desai, Jaydev P; Gullapalli, Rao P; Chen, Yu

2013-04-01

439

Medial temporal cortices in ex vivo magnetic resonance imaging.  

PubMed

This review focuses on the ex vivo magnetic resonance imaging (MRI) modeling of medial temporal cortices and associated structures, the entorhinal verrucae and the perforant pathway. Typical in vivo MRI has limited resolution due to constraints on scan times and does not show laminae in the medial temporal lobe. Recent studies using ex vivo MRI have demonstrated lamina in the entorhinal, perirhinal, and hippocampal cortices. These studies have enabled probabilistic brain mapping that is based on the ex vivo MRI contrast, validated to histology, and subsequently mapped onto an in vivo spherically warped surface model. Probabilistic maps are applicable to other in vivo studies. J. Comp. Neurol. 521:4177-4188, 2013. © 2013 Wiley Periodicals, Inc. PMID:23881818

Augustinack, Jean C; van der Kouwe, André J W; Fischl, Bruce

2013-12-15

440

Surveying the plant's world by magnetic resonance imaging.  

PubMed

Understanding the way in which plants develop, grow and interact with their environment requires tools capable of a high degree of both spatial and temporal resolution. Magnetic resonance imaging (MRI), a technique which is able to visualize internal structures and metabolites, has the great virtue that it is non-invasive and therefore has the potential to monitor physiological processes occurring in vivo. The major aim of this review is to attract plant biologists to MRI by explaining its advantages and wide range of possible applications for solving outstanding issues in plant science. We discuss the challenges and opportunities of MRI in the study of plant physiology and development, plant-environment interactions, biodiversity, gene functions and metabolism. Overall, it is our view that the potential benefit of harnessing MRI for plant research purposes is hard to overrate. PMID:22449048

Borisjuk, Ljudmilla; Rolletschek, Hardy; Neuberger, Thomas

2012-04-01

441

Magnetic resonance imaging of transfusional hemosiderosis complicating thalassemia major  

SciTech Connect

Tissue deposits of hemosiderin, a paramagnetic iron-protein complex, resulted in marked abnormalities of magnetic resonance (MR) spin-echo signal intensity within the viscera of three children with transfusional hemosiderosis and thalassemia major. In all patients the liver and bone marrow demonstrated abnormally low spin-echo intensities and the kidneys and muscles had abnormally high intensities. These observations correlate with in vitro MR observation of ferric (Fe/sup +3/) solutions, in which concentrations of ferric salts greater than 20 mmol yielded higher intensities than did water alone. MR imaging is sensitive to the tissue deposition of hemosiderin, and MR intensity appears to provide a rough measure of the amount of iron deposited.

Brasch, R.C.; Wesbey, G.E.; Gooding, C.A.; Koerper, M.A.

1984-03-01

442

Measuring water distribution in extrudates using magnetic resonance imaging (MRI).  

PubMed

Magnetic resonance imaging (MRI) has been applied to the evaluation of the distribution of water in extrudates produced by extruding pastes. Two model drugs similar in chemical structure were mixed with microcrystalline cellulose (MCC) and with two different amounts of water and extruded at two different extrusion speeds using a ram extruder. Extrudates were collected during the steady-state stage of the extrusion profile and were analysed for the water distribution using MRI. The percolation threshold for each sample was calculated to evaluate the degree of water