CONCEPTS IN MAGNETIC RESONANCE, Issue 3 2010
Hammad Omer
Abstract Parallel acquisition of Magnetic Resonance Imaging (MRI) has the potential to significantly reduce the scan time. SENSE is one of the many techniques for the reconstruction of parallel MRI images. A generalized algorithm for SENSE reconstruction and theoretical background is presented. This algorithm can be used for SENSE reconstruction for any acceleration factor between 2 and 8, for any Phase Encode direction (Horizontal or Vertical), with or without Regularization. The user can select a particular type of Regularization. A GUI based implementation of the algorithm is also given. Signal-to-noise ratio, artefact power, and g -factor map are used to quantify the quality of reconstruction. The effects of different acceleration factors on these parameters are also discussed. The GUI based implementation of SENSE reconstruction provides an easy selection of various parameters needed for reconstruction of parallel MRI images and helps in an efficient reconstruction and analysis of the quality of reconstruction. © 2010 Wiley Periodicals, Inc. Concepts Magn Reson Part A 36A: 178,186, 2010. [source]

Evaluation of Right Ventricular Fibrosis in Adult Congenital Heart Disease Using Gadolinium-enhanced Magnetic Resonance Imaging: Initial Experience in Patients with Right Ventricular Loading Conditions

CONGENITAL HEART DISEASE, Issue 5 2006
Lopa P. Hartke MD
ABSTRACT Objective., Gadolinium-enhanced cardiac magnetic resonance imaging has been used to show myocardial fibrosis, a finding that appears as late gadolinium enhancement. Its role in the evaluation of right ventricular fibrosis in congenital heart disease is unclear. The purpose of this study was to demonstrate late gadolinium enhancement of the right ventricle in adult and adolescent congenital heart disease and to investigate the relationship between this enhancement and clinical and pathophysiological data. Design., In total, 24 patients, 16 patients with congenital heart disease and right ventricular loading conditions and 8 controls, underwent gadolinium-enhanced viability imaging. Diagnoses varied and included repaired, palliated, and unrepaired lesions. The presence and extent of right ventricular late gadolinium enhancement was compared with patient clinical and hemodynamic data. Exact Wilcoxon tests, Fisher's exact tests, and Spearman's rank correlation were used to compare variables. Results., Nine of 16 patients (56%) were found to have right ventricular late gadolinium enhancement, ranging from 5% to 80% of right ventricular myocardium affected (mean 36.1%, SD 29.7). The combination of right ventricular systolic pressure ,98 mm Hg and systemic oxygen saturation ,93% strongly suggested the presence of right ventricular late gadolinium enhancement (positive predictive value 100%), but no single variable or combination of variables could reliably predict its absence (negative predictive values ,75%). Extent of right ventricular late gadolinium enhancement did not correlate with degree of either hypoxia or right ventricular hypertension. Conclusions., Gadolinium-enhanced cardiac magnetic resonance demonstrates right ventricular late gadolinium enhancement in some patients with congenital heart disease and right ventricular loading conditions. Clinical variables were associated with the presence of fibrosis but did not reliably predict severity. Myocardial preservation is likely a multifactorial process that may affect the right and left ventricles differently. [source]

Auditory verb perception recruits motor systems in the developing brain: an fMRI investigation

DEVELOPMENTAL SCIENCE, Issue 6 2009
Karin Harman James
This study investigated neural activation patterns during verb processing in children, using fMRI (functional Magnetic Resonance Imaging). Preschool children (aged 4,6) passively listened to lists of verbs and adjectives while neural activation was measured. Findings indicated that verbs were processed differently than adjectives, as the verbs recruited motor systems in the frontal cortex during auditory perception, but the adjectives did not. Further evidence suggested that different types of verbs activated different regions in the motor cortex. The results demonstrate that the motor system is recruited during verb perception in the developing brain, reflecting the embodied nature of language learning and processing. [source]

Dobutamine Stress Magnetic Resonance Imaging

ECHOCARDIOGRAPHY, Issue 3 2007
F.A.C.C., F.A.C.P., F.A.S.E., Pairoj Rerkpattanapipat M.D.
Measurements of left ventricular function with cardiovascular magnetic resonance (CMR) at rest and during intravenous dobutamine are useful for identifying myocardial ischemia, viability, and the risk of subsequent cardiovascular events. Without ionizing radiation, intravascular iodinated contrast administration, or acoustic window limitations, CMR has emerged as a useful adjunct to transthoracic echocardiography for assessing patients with or suspected of having coronary artery disease. [source]

Live/Real Time Three-Dimensional Transthoracic Echocardiographic Assessment of Left Ventricular Volumes, Ejection Fraction, and Mass Compared with Magnetic Resonance Imaging

ECHOCARDIOGRAPHY, Issue 2 2007
Xin Qi M.D.
Due to reliance upon geometric assumptions and foreshortening issues, the traditionally utilized transthoracic two-dimensional echocardiography (2DTTE) has shown limitations in assessing left ventricular (LV) volume, mass, and function. Cardiac magnetic resonance imaging (MRI) has shown potential in accurately defining these LV characteristics. Recently, the emergence of live/real time three-dimensional (3D) TTE has demonstrated incremental value over 2DTTE and comparable value with MRI in assessing LV parameters. Here we report 58 consecutive patients with diverse cardiac disorders and clinical characteristics, referred for clinical MRI studies, who were evaluated by cardiac MRI and 3DTTE. Our results show good correlation between the two modalities. [source]

Magnetic Resonance Imaging in the Study of the Lithium,Pilocarpine Model of Temporal Lobe Epilepsy in Adult Rats

EPILEPSIA, Issue 4 2002
Catherine Roch
Summary: ,Purpose: In temporal lobe epilepsy, it remains to be clarified whether hippocampal sclerosis is the cause or the consequence of epilepsy. We studied the temporal evolution of the lesions in the lithium,pilocarpine model of epilepsy in the rat with magnetic resonance imaging (MRI) to determine the progressive morphologic changes occurring before the appearance of chronic epilepsy. Methods: MRI was performed on an MR scanner operating at 4.7 T. We followed the evolution of lesions using T2 - and T1 -weighted sequences before and after the injection of gadolinium from 2 h to 9 weeks. Results: At 2 h after status epilepticus (SE), a blood,brain barrier breakdown could be observed only in the thalamus; it had disappeared by 6 h. At 24 h after SE, edema was present in the amygdala and the piriform and entorhinal cortices together with extensive neuronal loss; it disappeared progressively over a 5-day period. During the chronic phase, a cortical signal reappeared in all animals; this signal corresponded to gliosis, which appeared on glial fibrillary acidic protein (GFAP) immunohistochemically stained sections as hypertrophic astrocytes with thickened processes. In the hippocampus, the correlation between histopathology and T2 -weighted signal underscored the progressive constitution of atrophy and sclerosis, starting 2 days after SE. Conclusions: These data show the reactivity of the cortex that characterizes the initial step leading to the development of epilepsy and the late gliosis that could result from the spontaneous seizures. Moreover, it appears that hippocampal sclerosis progressively worsened and could be both the cause and the consequence of epileptic activity. [source]

Synthesis of PEOlated Fe3O4@SiO2 Nanoparticles via Bioinspired Silification for Magnetic Resonance Imaging

ADVANCED FUNCTIONAL MATERIALS, Issue 5 2010
Happy Tan
Abstract Inspired by the biosilification process, a highly benign synthesis strategy is successfully developed to synthesize PEOlated Fe3O4@SiO2 nanoparticles (PEOFSN) at room temperature and near-neutral pH. The success of such a strategy lies in the simultaneous encapsulation of Fe3O4 nanocrystals and silica precursors into the core of PEO-based polymeric micelles. The encapsulation results in the formation of a silica shell being confined to the interface between the core and corona of the Fe3O4 -nanocrystal-loaded polymeric micelles. Consequently, the surface of the Fe3O4@SiO2 nanoparticle is intrinsically covered by a layer of free PEO chains, which enable the PEOFSN to be colloidally stable not only at room temperature, but also upon incubation in the presence of proteins under physiological conditions. In addition, the silica shell formation does not cause any detrimental effects to the encapsulated Fe3O4 nanocrystals with respect to their size, morphology, crystallinity, and magnetic properties, as shown by their physicochemical behavior. The PEOFSN are shown to be good candidates for magnetic resonance imaging (MRI) contrast agents as demonstrated by the high r2/r1 ratio with long-term stability under high magnetic field, as well as the lack of cytotoxicity. [source]

A Computational Framework for Patient-Specific Analysis of Articular Cartilage Incorporating Structural Information from DT-MRI

GAMM - MITTEILUNGEN, Issue 2 2009
David M. Pierce
Abstract Accurate techniques for simulating sof t biological tissue deformation are an increasingly valuable tool in many areas of biomechanical analysis and medical image computing. To model the morphology and the material response of human articular cartilage a phenomenological and patient-specific simulation approach incorporating the collagen fibre fabric is proposed. We then demonstrate a unique combination of ultra-high field Diffusion Tensor Magnetic Resonance Imaging (17.6T DT-MRI) and a novel numerical approach incorporating the empirical data to predict the collagen fibre fabric deformation for an indentation experiment (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Supercritical-Fluid-Assisted One-Pot Synthesis of Biocompatible Core(, -Fe2O3)/Shell(SiO2) Nanoparticles as High Relaxivity T2 -Contrast Agents for Magnetic Resonance Imaging

ADVANCED FUNCTIONAL MATERIALS, Issue 14 2009
Elena Taboada
Abstract Monodisperse iron oxide/microporous silica core/shell composite nanoparticles, core(, -Fe2O3)/shell(SiO2), with a diameter of approximately 100,nm and a high magnetization are synthesized by combining sol,gel chemistry and supercritical fluid technology. This one-step processing method, which is easily scalable, allows quick fabrication of materials with controlled properties and in high yield. The particles have a specific magnetic moment (per kg of iron) comparable to that of the bulk maghemite and show superparamagnetic behavior at room temperature. The nanocomposites are proven to be useful as T2 MRI imaging agent. They also have potential to be used in NMR proximity sensing, theranostic drug delivery, and bioseparation. [source]

Diffusion-Weighted Magnetic Resonance Imaging During the Aura of Pseudomigraine With Temporary Neurologic Symptoms and Lymphocytic Pleocytosis

HEADACHE, Issue 4 2002
Florian Gekeler MD
A typical feature of pseudomigraine with temporary neurologic symptoms and lymphocytic pleocytosis (PMP) is the long duration of aura symptoms. To determine if these prolonged auras cause early ischemic parenchymal changes, we performed diffusion-weighted magnetic resonance imaging during the aura of a patient with PMP and found no reduction of water diffusion. [source]

Attachment style, affective loss and gray matter volume: A voxel-based morphometry study

HUMAN BRAIN MAPPING, Issue 10 2010
Stefania Benetti
Abstract Early patterns of infant attachment have been shown to be an important influence on adult social behavior. Animal studies suggest that patterns of early attachment influence brain development, contributing to permanent alterations in neural structure; however, there are no previous studies investigating whether differences in attachment style are associated with differences in brain structure in humans. In this study, we used Magnetic Resonance Imaging (MRI) and voxel-based morphometry (VBM) to examine for the first time the association between attachment style, affective loss (for example, death of a loved one) and gray matter volume in a healthy sample of adults (n = 32). Attachment style was assessed on two dimensions (anxious and avoidant) using the ECR-Revised questionnaire. High attachment-related anxiety was associated with decreased gray matter in the anterior temporal pole and increased gray matter in the left lateral orbital gyrus. A greater number of affective losses was associated with increased gray matter volume in the cerebellum; in this region, however, the impact of affective losses was significantly moderated by the level of attachment-related avoidance. These findings indicate that differences in attachment style are associated with differences in the neural structure of regions implicated in emotion regulation. It is hypothesized that early attachment experience may contribute to structural brain differences associated with attachment style in adulthood; furthermore, these findings point to a neuronal mechanism through which attachment style may mediate individual differences in responses to affective loss. Hum Brain Mapp, 2010. © 2010 Wiley-Liss, Inc. [source]

Dendrimer-Functionalized Shell-crosslinked Iron Oxide Nanoparticles for In-Vivo Magnetic Resonance Imaging of Tumors,

ADVANCED MATERIALS, Issue 9 2008
Xiangyang Shi
A powerful magnetic nanoprobe with folic acid (FA)-targeting ligands is fabricated by dendrimer functionalization of Fe3O4 nanoparticles (NPs) precoated with crosslinkable and biocompatible polymer multilayer shells. This magnetic probe allows for magnetic resonance imaging of FA receptor-overexpressing tumor cells in vitro and of an early-stage tumor model in vivo (see picture). [source]

Three-dimensional MRI mapping of minimum temperatures achieved in microwave and conventional food processing

INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 3 2001
John R. Bows
Microbiological assurance protocols for food preservation are based on the ,worst-case' slowest heating point within the food product. For conduction-limited processing, this leads to well-known overheating near surface regions of products, with resultant quality loss. For volumetric heating processes such as microwave heating, it is practically impossible to guarantee where the slowest heating point will be. Consequently, microwave heating regimes are generally excessive and product quality is often similar to conventional conduction-limited heating processes. It is well known that Magnetic Resonance Imaging (MRI) can provide three-dimensional (3D) images which quantify the spatial distribution of water in foods, and also that the MRI parameters of water are temperature dependent. The present study demonstrates that a combination of these two concepts has led to a new approach for the validation of thermal processing in food manufacture. The potential for on-line assurance of minimum and maximum temperatures for manufacture of microbiologically assured, minimally processed, high quality food is discussed. [source]

Integrated Microwave and Optical Scanning Probe for Magnetic Resonance Imaging

ISRAEL JOURNAL OF CHEMISTRY, Issue 1 2008
Fadi Sakran
We demonstrate a scanning microwave near-field probe based on a slit aperture that is capable of performing spatially-resolved magnetic resonance measurements in the frequency range of 3,90 GHz. We demonstrate local electron spin resonance (ESR), ferromagnetic resonance (FMR), and spin-wave resonance (SWR) studies on model materials. The probe can serve as a local contactless heater as well. We demonstrate also a further application, a dual microwave/optical near-field probe that can be useful in contactless measurements of photoconductivity and fluorescence under microwave irradiation. [source]

Functional and Cognitive Consequences of Silent Stroke Discovered Using Brain Magnetic Resonance Imaging in an Elderly Population

JOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 7 2004
Wolf-Peter Schmidt MD
Objectives: To evaluate the prevalence of silent stroke and its associated consequences on physical, cognitive, and emotional functioning in an elderly population. Design: Population-based cross-sectional survey. Setting: The Memory and Morbidity in Augsburg Elderly project in the Augsburg region of southern Germany. Participants: Two hundred sixty-seven community-dwelling persons aged 65 to 83. Measurements: The presence of silent stroke was determined using magnetic resonance imaging brain scan and a single question asking for physician-diagnosed stroke in each participant. The health effect of silent stroke was assessed using rating scales for self-perceived health status (36-item short-form health survey), activities of daily living (ADLs) and instrumental ADLs, cognitive function, and depression (Center for Epidemiologic Studies Depression scale). Results: Just fewer than 13% (12.7%) of participants were affected by silent stroke. Silent stroke was associated with a history of hypertension, heart surgery, and elevated C-reactive protein. Individuals with silent stroke showed impairments on the Mini-Mental State Examination test and in the cognitive domains of memory, procedural speed, and motor performance. Conclusion: The presence of silent stroke has a considerable effect on cognitive performance in those affected. Determining the presence of silent stroke using brain imaging may contribute to identifying individuals at risk for developing gradual neurological deficits. [source]

Cerebral Diffusion-Weighted Magnetic Resonance Imaging: A Tool to Monitor the Thrombogenicity of Left Atrial Catheter Ablation

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 1 2006
LARS LICKFETT M.D.
Introduction: Cerebral embolism and stroke are feared complications of left atrial catheter ablation such as pulmonary vein (PV) ablation. In order to assess the thrombogenicity of left atrial catheter ablation, knowledge of both clinically evident as well as silent cerebral embolism is important. The aim of the current study was to examine the use of diffusion-weighted magnetic resonance imaging (DW-MRI) for detection of cerebral embolism, apparent as well as silent, caused by PV catheter ablation. Methods and Results: Twenty consecutive patients without structural heart disease undergoing lasso catheter-guided ostial PV ablation using an irrigated-tip ablation catheter were studied. Cerebral MRI including DW single-shot spin echo echoplanar, turbo fluid attenuated inversion recovery, and T2-weighted turbo spin echo sequences were performed the day after the ablation procedure. Ten patients also underwent preprocedure cerebral MRI. All ablation procedures were performed without acute complications. A mean of 3.2 ± 0.6 PVs were ablated per patient. No patient had neurological symptoms following the procedure. In 2 of 20 patients (10%), DW-MRI revealed new embolic lesions, which were located in the right periventricular white matter in one and in the left temporal lobe in the other patient. There was no statistically significant difference in age, history of hypertension, left atrial volume, and procedure duration between the 2 patients with and the 18 patients without cerebral embolism following AF ablation. Conclusion: This is the first study using highly sensitive DW-MRI of the brain to detect asymptomatic cerebral embolism after left atrial catheter ablation. Even small, clinically silent, embolic lesions can be demonstrated with this technique. DW-MRI can be used to monitor and compare the thrombogenicity of different AF ablation approaches. [source]

Assessment of Pulmonary Vein Anatomic Variability by Magnetic Resonance Imaging:

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 4 2004
Implications for Catheter Ablation Techniques for Atrial Fibrillation
Introduction: Pulmonary vein (PV) isolation for atrial fibrillation (AF) currently is performed using either an ostial or an extra-ostial approach. The objective of this study was to analyze by three-dimensional (3D) magnetic resonance angiography (MRA) the anatomy of the PVs in order to detect structural variability that would impact the choice of ablation approach. Methods and Results: Three-dimensional MRA was performed in 105 patients undergoing PV isolation. The ostial diameter, branching pattern, and PV angulation were analyzed. Fifty-nine (56%) patients had the typical pattern of 4 PVs with 4 separate ostia, 30 (29%) patients had an additional PV, and 18 (17%) patients had a left common PV trunk. In two patients, there were three right-sided veins and a common left-sided trunk, giving rise to four ostia: three on the right and one on the left. Two different populations of right middle PVs were noted: one where the additional vein projected anteriorly to drain the right middle lobe and one posterior to drain the superior portion of the right lower lobe. The average intrapatient variability in PV diameter was 7.9 ± 4.2 mm. The PV ostium was <10 mm in 26 (25%) patients and >25 mm in 15 (14%) patients. The first branch originated 6.7 ± 2.3 mm from the ostium. The left superior, right superior, right inferior, and left inferior PVs were found to enter the left atrium at the following angles: 32 ± 13°, 131 ± 11°, 206 ± 16°, and 329 ± 14°, respectively. Forty-nine patients (47%) had at least one funnel shaped PV. Conclusion: This largest PV imaging study to date demonstrates that MRA is a valuable tool that allows detection of marked intrapatient and interpatient anatomic variability of the PVs. These findings suggest that, at least in some patients, circumferential extra-ostial left atrial encirclement of the PVs may be preferable to ostial PV isolation. These findings also may have significant implications on the future development of coil- and balloon-based catheter ablation designs for AF ablation. (J Cardiovasc Electrophysiol, Vol. 15, pp. 387-393, April 2004) [source]

Magnetic Resonance Imaging in the staging of cervical carcinoma: A pictorial review

JOURNAL OF MEDICAL IMAGING AND RADIATION ONCOLOGY, Issue 5 2008
GEC Smith
Summary The purposes of diagnostic imaging in cervical carcinoma are to determine the size and extent of the tumour for accurate staging and to establish lymph node status. Historically, cervical tumours were staged by clinical examination and by examination under anaesthesia according to the International Federation of Gynecology and Obstetrics staging system. This system does not incorporate imaging findings or lymph node status, but it is now accepted that cross-sectional imaging, and in particular MRI, has an important role to play in the staging of these tumours. We carried out an audit of all patients having a staging MRI for suspected cervical carcinoma in South Australia and the Northern Territory for 2 years from January 2005. This was the first time the clinicians had been offered routine MRI, and despite the strong supporting published reports, they had some reservations about its performance. Our audit covered a wide range of tumour stages and provided a good teaching resource for radiologists and clinicians alike. [source]

Functional Magnetic Resonance Imaging in Conscious Animals: A New Tool in Behavioural Neuroscience Research

JOURNAL OF NEUROENDOCRINOLOGY, Issue 5 2006
C. F. Ferris
First page of article [source]

Magnetic Resonance Imaging of the Hypothalamic-Neurohypophyseal System

JOURNAL OF NEUROENDOCRINOLOGY, Issue 4 2004
I. Fujisawa
Abstract Magnetic resonance imaging (MRI) is a revolutionary advance in diagnostic imaging of the hypothalamic-neurohypophyseal system (HNS). The detailed anatomy of the sellar and parasellar region is clearly visible using MRI, because it has no bony artifacts and multidirectional capability. The posterior lobe of the pituitary gland displays a characteristic bright signal on the MR T1-weighted image (T1WI), and is distinctly separated from the anterior lobe. The bright signal is absent in patients with central diabetes insipidus, and is thought to reflect normal vasopressin storage in the posterior lobe. The signal intensity ratio of the posterior lobe to the pons on T1WI is strongly correlated with vasopressin content in the posterior lobe. In addition to the morphological evaluation, MRI provides unique information concerning the function of the HNS. The MRI findings of the HNS (normal condition, central diabetes insipidus, a depleted posterior lobe, an ectopic posterior lobe, and a damming-up phenomenon of the neurosecretory vesicles in the pituitary stalk) are demonstrated in this article. [source]

Rheumatoid Leptomeningitis: Magnetic Resonance Imaging and Pathologic Findings,A Case Report

JOURNAL OF NEUROIMAGING, Issue 2 2010
Alessandro Cianfoni MD
ABSTRACT BACKGROUND AND PURPOSE Rheumatoid arthritis (RA) is a chronic inflammatory multisystem disease with articular and extra-articular manifestations. Intracranial manifestations of RA are rare. Purpose of this article is to report on a rarely described leptomeningeal involvement in RA, and on its neuroimaging features, including diffusion-weighted imaging (DWI). METHODS The authors describe the case of a 74-year-old woman with a 5-year history of RA presenting with progressive left-side weakness and hypoesthesia. The patient underwent laboratory investigation and brain contrast-enhanced MRI, also with DWI, before undergoing brain biopsy. RESULTS Neuroimaging revealed abnormal high T2-signal in right frontal and parietal lobes, restricted diffusion in the subarachnoid space, and diffuse thick linear leptomeningeal contrast-enhancement. These findings were interpreted as rheumatoid leptomeningitis, and brain biopsy confirmed this diagnosis. CONCLUSIONS In summary, rheumatoid meningitis is a rare neurological complication of RA, but it should be considered in the proper clinical setting when patient presentation and laboratory results fail to support the other differential diagnostic possibilities proposed by the MR imaging findings. [source]

Diffusion Tensor and Functional Magnetic Resonance Imaging of Diffuse Axonal Injury and Resulting Language Impairment

JOURNAL OF NEUROIMAGING, Issue 4 2007
Hui Mao PhD
ABSTRACT Diffuse axonal injury (DAI) is a common aftermath of brain trauma. The diagnosis of DAI is often difficult using conventional magnetic resonance imaging (MRI). We report a diffusion tensor imaging (DTI) study of a patient who sustained DAI presenting with language impairment. Fractional anisotropy (FA) and DTI tractography revealed a reduction of white matter integrity in the left frontal and medial temporal areas. White matter damage identified by DTI was correlated with the patient's language impairment as assessed by functional MRI (fMRI) and a neuropsychological exam. The findings demonstrate the utility of DTI for identifying white matter changes secondary to traumatic brain injury (TBI). [source]

Measurement of Brain and Spinal Cord Atrophy by Magnetic Resonance Imaging as a Tool to Monitor Multiple Sclerosis

JOURNAL OF NEUROIMAGING, Issue 2005
FAAN, Rohit Bakshi MD
ABSTRACT Evaluation of brain and spinal cord atrophy by magnetic resonance imaging (MRI) has become an increasingly important component of understanding the multiple sclerosis (MS) disease process. These destructive aspects of the disease develop early in the disease course. A growing body of data links brain and spinal cord atrophy to clinical impairment more closely than can be linked with conventional measures of overt lesions. Thus, irreversible tissue damage may be a key factor leading to disease progression. In this review, the authors present the proposed mechanisms leading to central nervous system (CNS) atrophy. They describe the available MRI-based techniques to measure regional and global atrophy of the brain and spinal cord. They compare the rate of atrophy among MS phenotypes and summarize the emerging data linking atrophy to neurological and neuropsychological impairment. Finally, they discuss the effect of disease-modifying immunotherapies on the rate of CNS atrophy in patients with MS. Future research to clarify the etiology and pathophysiology of brain and spinal cord atrophy should provide new targets for therapeutic development. [source]

Magnetic Resonance Imaging and Diffusion-Weighted Imaging Changes After Hypoglycemic Coma

JOURNAL OF NEUROIMAGING, Issue 2 2005
S. L. Jung
ABSTRACT The authors report a case of severe hypoglycemic encephalopathy in an elderly patient. The magnetic resonance images showed bilateral cortical signal changes and basal ganglia lesions, which spared the thalami. The lesions were bright on fluid-attenuated inversion recovery and diffusion-weighted images and dark on the apparent diffusion coefficient map, being more conspicuous on the diffusion-weighted images than on the fluid-attenuated inversion recovery images. A literature review of the imaging features and pathophysiological mechanism in comparison with those of hypoxic ischemic injury is discussed. [source]

Functional Magnetic Resonance Imaging of Working Memory among Multiple Sclerosis Patients

JOURNAL OF NEUROIMAGING, Issue 2 2004
Lawrence H. Sweet PhD
ABSTRACT Background and Purpose. Verbal working memory (VWM) deficits have been a well-replicated finding among patients with multiple sclerosis (MS). Functional magnetic resonance imaging (FMRI) studies have described a VWM system in healthy samples; however, functional neuroimaging of this system among MS patients is just beginning to appear. Methods. Fifteen MS patients and 15 sex-, age-, education-, and IQ-matched healthy control (HC) participants completed a 2-Back VWM task as whole-brain FMRI was conducted. Results. Each group exhibited increased brain activity compared to the 0-Back control task in regions associated with the 2-Back in previous neuroimaging studies. These included Broca's area, supplementary motor area (SMA), premotor cortices (PMC), and dorsolateral prefrontal cortices (DLPFC). MS patients exhibited greater cortical activity than did HC participants in left primary motor and somatosensory cortices, PMC, DLPFC, anterior cingulate, and bilateral SMA. MS patients exhibited relatively less activation in Broca's area, bilateral cerebellum, and other regions not typically associated with the 2-Back (eg, right fusiform gyrus, left lingual gyrus, right hippocampus). Performance accuracy and reaction time did not differ between groups. Conclusions. Normal performance of a challenging VWM task among high-functioning MS patients is associated with a shift toward greater activity in regions related to sensorimotor functions and anterior attentional/executive components of the VWM system. Posterior memory storage systems appeared unaffected, while portions of the visual processing and subvocal rehearsal systems were less active. Although a shift in neural activity was noted relative toHC participants, deviation from regions normally involved in VWM function was not observed in this patient sample. [source]

Magnetic Resonance Imaging of Meningoradiculomyelitis in Early Disseminated Lyme Disease

JOURNAL OF NEUROIMAGING, Issue 3 2003
Mark J. Tullman MD
ABSTRACT Lyme disease, a multisystem illness caused by the spirochete Borrelia burgdorferi, is the most common vector-borne disease in the United States. There are 3 clinical stages of Lyme disease: early localized, early disseminated, and late persistent disease. Neuroborreliosis, infection of the nervous system by B. burgdorferi, may occur during early disseminated or late persistent disease. Spinal cord involvement in early disseminated disease is extremely rare. In patients with early disseminated neuroborreliosis, treatment with antibiotics often leads to rapid recovery and may prevent further complications of Lyme disease. The authors present the clinical and radiographic findings, both before and after treatment, in a patient with meningoradiculomyelitis due to early disseminated Lyme disease. [source]

Diffusion Magnetic Resonance Imaging in Intermediate Form of Maple Syrup Urine Disease

JOURNAL OF NEUROIMAGING, Issue 4 2002
R. N. Sener
ABSTRACT An 8-year-old boy with the intermediate variant of maple syrup urine disease is reported. On b= 1000 s/mm2 (heavily diffusion weighted) images of diffusion magnetic resonance imaging, there was symmetric high signal in the globus pallidus, mesencephalon, dorsal pons, and nucleus dentatus, consistent with restriction of the mobility of water molecules. Apparent diffusion coefficient (ADC) maps revealed low ADC values ranging from 0.42 to 0.56 ?10,3mm2/s in these regions, compared to those of apparently unaffected regions in the brain parenchyma ranging from 0.63 to 0.97 ?10,3 mm 2/s. It is suggested that the areas of increased signal (and low ADC values) are the result of dysmyelination as a reflection of disorganized tissue integrity. [source]

Magnetic Resonance Imaging in Patients Diagnosed With Papilledema: A Comparison of 6 Different High-Resolution T1- and T2(*)-Weighted 3-Dimensional and 2-Dimensional Sequences

JOURNAL OF NEUROIMAGING, Issue 2 2002
Johannes Seitz MD
ABSTRACT Purpose. To evaluate visualization and signal characteristics of macroscopic changes in patients with ophthalmologically stated papilledema and to find a suitable high-resolution magnetic resonance imaging (MRI) protocol. Method. Nine consecutive patients with 12 ophthalmologically stated papilledemas underwent MRI of the head and orbits, which consisted of the following high-resolution sequences: 3-dimensional (3D), T2*-weighted (T2*w) constructive interference in steady-state sequence (CISS); 3D, T1-weighted (T1w) magnetization prepared-rapid gradient echo sequence (MP-RAGE) (with and without intravenous contrast medium); transverse 3D and 2-dimensional (2D) (2mm), T2-weighted (T2w) turbo spin echo (TSE); transverse 2D (2mm), contrast-enhanced T1w TSE with fat-suppression technique; and transverse 2D (5mm), T2w TSE. A quantitative and qualitative evaluation of the papilla, optic nerve, optic nerve sheath, optic chiasm, and the brain was performed. The 6 high-resolution sequences were compared. Results. The elevation of the optic disc into the optic globe in ophthalmologically stated papilledema was best visualized in T2w, 3D CISS sequence. The pathological contrast enhancement was best seen in T1w contrast-enhanced 2D TSE sequence with fat-suppression technique. The mean width of the optic nerve sheath directly behind the globe was 7.54 mm (± 1.05 mm) in the pathological eyes, compared to 5.52 mm (± 1.11 mm) in the normal eyes. In all patients, the cerebral indices calculated showed no signs of increased intracranial pressure or other abnormalities changing the volume of the brain or ventricles. The contrast of the orbital fat versus the optic nerve sheath, the optic nerve sheath versus the surrounding cerebrospinal fluid (CSF), the surrounding CSF versus the optic nerve, the optic chiasm versus the CSF, and the optic papilla versus the optic globe were best visualized in the 3D, T2*w CISS sequence. An enhancement of the swollen optic nerve head was best seen in all 12 cases in the T1w contrast-enhanced 2D TSE sequence with fat-suppression technique. Conclusion. An MRI protocol consisting of a 5-mm transverse T2w TSE sequence; a T2*w, 3D CISS sequence; a T1w, 3D MP-RAGE sequence with and without contrast medium; and a transverse T1w, (2-mm) 2D TSE sequence with fat-suppression technique with intravenous contrast medium is suitable to visualize the macroscopic changes in papilledema. In addition, this combination is an excellent technique for the examination of the orbits and the brain. [source]

Magnetic Resonance Imaging and Histological Classification of Intracranial Meningiomas in 112 Dogs

JOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 3 2008
B.K. Sturges
Background: Intracranial meningiomas are the most common primary brain tumors in dogs. Classification of meningiomas by tumor grade and subtype has not been reported, and the value of magnetic resonance imaging (MRI) characteristics for predicting tumor subtype and grade has not been investigated. Hypothesis: Canine intracranial meningiomas are a heterogenous group of tumors with differing histological subtypes and grades. Prediction of histopathological classification is possible based on MRI characteristics. Animals: One hundred and twelve dogs with a histological diagnosis of intracranial meningioma. Methods: Retrospective observational study. Results: Meningiomas were overrepresented in the Golden Retriever and Boxer breeds with no sex predilection. The incidence of specific tumor grades was 56% benign (Grade I), 43% atypical (Grade II), and 1% malignant (Grade III). Grade I histological subtypes included meningothelial (43%), transitional (40%), microcystic (8%), psammomatous (6%), and angiomatous (3%). No statistically significant (P < .05) associations were found among tumor subtype or grade and any of the MRI features studied. Conclusions and Clinical Importance: Meningiomas in dogs differ from their counterparts in humans mainly in their higher incidence of atypical (Grade II) tumors observed. MRI characteristics do not allow for prediction of meningioma subtype or grade, emphasizing the necessity of histopathology for antemortem diagnosis. The higher incidence of atypical tumors in dogs may contribute to the poorer therapeutic response in dogs with meningiomas as compared with the response in humans with meningiomas. [source]