Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Structural MRI”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 991 records · Page 55Linked to original sources
PubMed2002

[Synovial chondromatosis as an unusual cause for subacromial impingement in a tennisplayer].

On the one hand synovial chondromatosis is a rare disorder and usually involves the knee and hip but rarely the shoulder joint. On the other hand bursal causes of impingement are rare too. We report a case of synovial osteochondromatosis presenting as chronic impingement syndrome in a 44 year old hobby tennis player. In the course of four years impingement problems and a "tumorous" growth on the outer surface attacked attraction to the patient. An MRI presented several nodular structures with sclerosis in the anteriomedial region of the shoulder joint. The mass was completely removed by operative treatment. The histological result showed a synovial chondromatosis with chronical synovitis. After the operative exstirpation of the calcified bodies the patient had no discomfort for 15 months and is now able to play tennis again.

Adult↗
PubMedDate not supplied

Painful scoliosis.

In case of painful scoliosis, a search for etiologic factors in the vertebral spinal canal and adjacent structures should be made. MRI with Gadolinium is useful to look for various pathology in and around the spine in particular of spinal cord. CT scanning is indispensible for bony details. Thus CT and MRI are complementary in evaluation of pathology of spine in any modern imaging centers.

Adolescent↗
PubMed2005

Thickness of ventromedial prefrontal cortex in humans is correlated with extinction memory.

The ventromedial prefrontal cortex (vmPFC) has been implicated in fear extinction [Phelps, E. A., Delgado, M. R., Nearing, K. I. & Ledoux, J. E. (2004) Neuron 43, 897-905; Herry, C. & Garcia, R. (2003) Behav. Brain Res. 146, 89-96]. Here, we test the hypothesis that the cortical thickness of vmPFC regions is associated with how well healthy humans retain their extinction memory a day after having been conditioned and then extinguished. Fourteen participants underwent a 2-day fear conditioning and extinction protocol. The conditioned stimuli (CSs) were pictures of virtual lights, and the unconditioned stimulus (US) was an electric shock. On day 1, participants received 5 CS+US pairings (conditioning), followed by 10 CS trials with no US (extinction). On day 2, the CS was presented alone to test for extinction memory. Skin conductance response (SCR) was the behavioral index of conditioning and extinction. Participants underwent MRI scans to obtain structural images, from which cortical thickness was measured. We performed a vertex-based analysis across the entire cortical surface and a region-of-interest analysis of a priori hypothesized territories to measure cortical thickness and map correlations between this measure and SCR. We found significant, direct correlation between thickness of the vmPFC, specifically medial orbitofrontal cortex, and extinction retention. That is, thicker medial orbitofrontal cortex was associated with lower SCR to the conditioned stimulus during extinction recall (i.e., greater extinction memory). These results suggest that the size of the vmPFC might explain individual differences in the ability to modulate fear among humans.

Adult↗
PubMed2001

MRI findings concerning the lateral pterygoid muscle in patients with symptomatic TMJ hypermobility.

Clinical studies have shown a close association between temporomandibular joint hypermobility (TMJH) and temporomandibular disorders (TMD). While pathological change of the lateral pterygoid muscle (LPM) is one of the most emphasized in studies of TMD, there have been no detailed clinical reports of the LPM studies using magnetic resonance imaging (MRI) in TMJH. This study investigates structural and pathological alterations involving the LPM in patients with TMJH using MRI. A retrospective analysis was made of high-field MRI images from 98 patients with TMJH. LPMs of 143 joints were analyzed. In 110 joints (77%), hypertrophy, atrophy, and contracture were found in the superior belly and/or the inferior belly of the LPM. Pathological changes were more frequently found in the superior rather than the inferior belly of the LPM. In the cases with abnormalities in both bellies of the LPM, hypertrophy of the inferior belly was usually found combined with other changes of the SBLPM. The results of this study indicated that the pathological changes of the LPM or MRI are not infrequent in patients with symptomatic TMJH.

Adolescent↗
PubMedDate not supplied

Multimodal neuroimaging studies and neurodevelopment and neurodegeneration hypotheses of schizophrenia.

The interpretation of the huge number of results in schizophrenia research using neuroimaging is uncertain. However, the simultaneous use of complimentary data obtained with these techniques may yield more relevant information in this regard. In this paper we present a series of studies performed by our group in two schizophrenic samples with the use of structural (magnetic resonance imaging, MRI), functional [glucose positron emission tomography (PET) and N-acetyl-aspartate (NAA) magnetic resonance spectrocopy] and neurophysiological techniques (the P300 event-related potential). Transversal and longitudinal measurements were performed.The integrated vision of the results so obtained allows us to propose the hypothesis of a neurodevelopmentally determined state of prefrontal disinihibition, in which the degree of atrophy would directly relate to the metabolic rate. This state would already be present in the first stages of illness and could have neurotoxic consequences in the long term. This would explain the findings of an association between sulcal cerebrospinal fluid (CSF) and illness duration and decreased NAA levels in chronic but not in recent-onset cases. The prefrotnal disinhibition would overstimulate the limbic system and the hippocampus would become overactivated, the metabolic rate at this level being inversely related to P300 amplitude. Clozapine showed a more selective and intense action on that hyperactive metabolic tone than haloperidol.

Journal Article↗
PubMed2006

Cognitive reserve as a resilience factor against depression after moderate/severe head injury.

Depression is one of the most frequently reported and distressing residual complaints in survivors of head injury. Studies investigating the pattern of neuropathology associated with depression post head injury have found little consistency. One explanation for this is that cognitive reserve "protects" against depression either through more efficient processing or more effective compensation. An alternative explanation is that previous studies have used relatively gross measures of lesion location, and variable inclusion criteria and times between scan and injury. This study explored these possibilities in a cohort of survivors of moderate-severe head injury at least 6 months post-injury. Volunteers completed neuropsychological assessments and structural magnetic resonance imaging (MRI) scans. A significant difference between depressed and non-depressed survivors was found, with higher intelligence associated with lower rates of depression. No significant anatomical differences were found between depressed and non-depressed survivors. These results suggest that premorbid intelligence may provide a resilience factor against depression in head injury survivors.

Adult↗
PubMed2003

A network of occipito-temporal face-sensitive areas besides the right middle fusiform gyrus is necessary for normal face processing.

Neuroimaging studies have identified at least two bilateral areas of the visual extrastriate cortex that respond more to pictures of faces than objects in normal human subjects in the middle fusiform gyrus [the 'fusiform face area' (FFA)] and, more posteriorly, in the inferior occipital cortex ['occipital face area' (OFA)], with a right hemisphere dominance. However, it is not yet clear how these regions interact which each other and whether they are all necessary for normal face perception. It has been proposed that the right hemisphere FFA acts as an isolated ('modular') processing system for faces or that this region receives its face-sensitive inputs from the OFA in a feedforward hierarchical model of face processing. To test these proposals, we report a detailed neuropsychological investigation combined with a neuroimaging study of a patient presenting a deficit restricted to face perception, consecutive to bilateral occipito-temporal lesions. Due to the asymmetry of the lesions, the left middle fusiform gyrus and the right inferior occipital cortex were damaged but the right middle fusiform gyrus was structurally intact. Using functional MRI, we disclosed a normal activation of the right FFA in response to faces in the patient despite the absence of any feedforward inputs from the right OFA, located in a damaged area of cortex. Together, these findings show that the integrity of the right OFA is necessary for normal face perception and suggest that the face-sensitive responses observed at this level in normal subjects may arise from feedback connections from the right FFA. In agreement with the current literature on the anatomical basis of prosopagnosia, it is suggested that the FFA and OFA in the right hemisphere and their re-entrant integration are necessary for normal face processing.

Discrimination, Psychological↗
PubMed2001

Prefrontal gray matter volume reduction in first episode schizophrenia.

Functional measures have consistently shown prefrontal abnormalities in schizophrenia. However, structural magnetic resonance imaging (MRI) findings of prefrontal volume reduction have been less consistent. In this study, we evaluated prefrontal gray matter volume in first episode (first hospitalized) patients diagnosed with schizophrenia, compared with first episode patients diagnosed with affective psychosis and normal comparison subjects, to determine the presence in and specificity of prefrontal abnormalities to schizophrenia. Prefrontal gray and white matter volumes were measured from first episode patients with schizophrenia (n = 17), and from gender and parental socio-economic status-matched subjects with affective (mainly manic) psychosis (n = 17) and normal comparison subjects (n = 17), age-matched within a narrow age range (18--29 years). Total (left and right) prefrontal gray matter volume was significantly reduced in first episode schizophrenia compared with first episode affective psychosis and comparison subjects. Follow-up analyses indicated significant left prefrontal gray matter volume reduction and trend level reduction on the right. Schizophrenia patients showed 9.2% reduction on the left and 7.7% reduction on the right compared with comparison subjects. White matter volumes did not differ among groups. These data suggest that prefrontal cortical gray matter volume reduction is selectively present at first hospitalization in schizophrenia but not affective psychosis.

Adolescent↗
PubMed2003

Mutations in the human LARGE gene cause MDC1D, a novel form of congenital muscular dystrophy with severe mental retardation and abnormal glycosylation of alpha-dystroglycan.

The congenital muscular dystrophies (CMD) are a heterogeneous group of autosomal recessive disorders. A new pathomechanism has recently been identified in a group of these disorders in which known or putative glycosyltransferases are defective. Common to all these conditions is the hypoglycosylation of alpha-dystroglycan. Fukuyama CMD, muscle-eye-brain disease and Walker-Warburg syndrome, each associated with eye abnormalities and neuronal migration defects, result from mutations in fukutin, POMGnT1 and POMT1, respectively, while mutations in the fukutin-related protein (FKRP) gene cause congenital muscular dystrophy 1C, typically lacking brain involvement. Another putative glycosyltransferase, Large, is mutated in the myodystrophy mouse. The human homologue of this gene is therefore a strong candidate for involvement in novel forms of muscular dystrophy. We studied 36 patients with muscular dystrophy and either mental retardation, structural brain changes or abnormal alpha-dystroglycan immunolabelling, unlinked to any reported CMD loci. Linkage analysis in seven informative families excluded involvement of LARGE but sequencing of this gene in the remaining 29 families identified one patient with a G1525A (Glu509Lys) missense mutation and a 1 bp insertion, 1999insT. This 17-year-old girl presented with congenital muscular dystrophy, profound mental retardation, white matter changes and subtle structural abnormalities on brain MRI. Her skeletal muscle biopsy showed reduced immunolabelling of alpha-dystroglycan. Immunoblotting with an antibody to a glycosylated epitope demonstrated a reduced molecular weight form of alpha-dystroglycan that retained some laminin binding activity. This is the first description of mutations in the human LARGE gene and we propose to name this new disorder MDC1D.

Adolescent↗
PubMed2001

Developmental prosopagnosia: should it be taken at face value?

This study presents a rare case of developmental prosopagnosia. Structural magnetic resonance imaging (MRI) revealed no overt brain abnormalities. EP's basic visual skills and visual memory were intact, as was his ability to judge age, sex and expression from faces, identify facial parts, and make face/non-face decisions. EP was impaired at recognizing famous and very familiar faces and describing visual images of famous faces. He also displayed an anterograde memory impairment for recently studied faces, and performed poorly on tests of unfamiliar face matching, most notably for chimeric faces. It is suggested that EP may be deficient at encoding configural representations of faces. EP appears to have a "pure" (i.e. specific to faces) prosopagnosia, as he shows normal object recognition from unusual viewpoints, good gestalt completion for objects, but not for faces, normal visual imagery for objects but not for faces, a disruption of the inversion effect for faces but not for houses, and performs within the normal range on tests of within-category discriminations, even with unique exemplars of object categories such as famous buildings.

Adult↗
PubMed1990

The role of imaging in screening for prostate cancer. A decision analysis perspective.

Using Bayesian and decision analytical concepts, we can define the ideal characteristics of any screening test for cancer of the prostate: high specificity, reasonably high sensitivity, noninvasiveness, low cost, and low interobserver variability. Computed tomography (CT) fails as a test, since it cannot show the internal structure of the prostate; MRI is too expensive and has an unacceptably poor specificity. Transrectal sonography does have many desirable characteristics, including relatively high sensitivity and, if no biopsy is done, low cost and noninvasiveness. But it has an unacceptably low specificity for early, clinically significant lesions: over half of all patients tested will have a positive result, requiring a confirming biopsy, which means that transrectal sonography will in the end be too invasive and too expensive. Therefore, we cannot recommend transrectal sonography as a primary screening tool for cancer of the prostate at this time.

Costs and Cost Analysis↗
PubMed2000

Quantitation of regional cerebral blood flow corrected for partial volume effect using O-15 water and PET: I. Theory, error analysis, and stereologic comparison.

Limited spatial resolution of positron emission tomography (PET) can cause significant underestimation in the observed regional radioactivity concentration (so-called partial volume effect or PVE) resulting in systematic errors in estimating quantitative physiologic parameters. The authors have formulated four mathematical models that describe the dynamic behavior of a freely diffusible tracer (H215O) in a region of interest (ROI) incorporating estimates of regional tissue flow that are independent of PVE. The current study was intended to evaluate the feasibility of these models and to establish a methodology to accurately quantify regional cerebral blood flow (CBF) corrected for PVE in cortical gray matter regions. Five monkeys were studied with PET after IV H2(15)O two times (n = 3) or three times (n = 2) in a row. Two ROIs were drawn on structural magnetic resonance imaging (MRI) scans and projected onto the PET images in which regional CBF values and the water perfusable tissue fraction for the cortical gray matter tissue (hence the volume of gray matter) were estimated. After the PET study, the animals were killed and stereologic analysis was performed to assess the gray matter mass in the corresponding ROIs. Reproducibility of the estimated parameters and sensitivity to various error sources were also evaluated. All models tested in the current study yielded PVE-corrected regional CBF values (approximately 0.8 mL x min(-1) x g(-1) for models with a term for gray matter tissue and 0.5 mL x min(-1) x g(-1) for models with a term for a mixture of gray matter and white matter tissues). These values were greater than those obtained from ROIs tracing the gray matter cortex using conventional H2(15)O autoradiography (approximately 0.40 mL x min(-1) x g(-1)). Among the four models, configurations that included two parallel tissue compartments demonstrated better results with regards to the agreement of tissue time-activity curve and the Akaike's Information Criteria. Error sensitivity analysis suggested the model that fits three parameters of the gray matter CBF, the gray matter fraction, and the white matter fraction with fixed white matter CBF as the most reliable and suitable for estimating the gray matter CBF. Reproducibility with this model was 11% for estimating the gray matter CBF. The volume of gray matter tissue can also be estimated using this model and was significantly correlated with the results from the stereologic analysis. However, values were significantly smaller compared with those measured by stereologic analysis by 40%, which can not be explained by the methodologic errors. In conclusion, the partial volume correction was essential in quantitation of regional CBF. The method presented in this article provided the PVE-corrected regional CBF in the cortical gray matter tissue. This study also suggests that further studies are required before using MRI derived anatomic information for PVE correction in PET.

Animals↗
PubMed2002

Alcoholism and AIDS: magnetic resonance imaging approaches for detecting interactive neuropathology.

Both alcohol abuse and human immunodeficiency virus (HIV) infection have deleterious effects on brain structure, metabolism and function. In individuals with both afflictions these effects are doubtless additive and may interact to produce synergistic adverse effects. Further, the normal processes of aging produce brain degeneration that leaves older people especially vulnerable to the untoward effects of alcohol abuse and HIV infection. Advances in in vivo brain imaging now make practical the clinical study of the interaction of alcoholism and HIV infection and the potential of increased vulnerability produced by advancing age. In addition to structural magnetic resonance imaging (MRI), which provides quantitative assessments of brain macrostructure, are diffusion tensor imaging (DTI), which assesses microstructural integrity, magnetic resonance spectroscopy (MRS), which provides assessment of brain chemical moieties related to neuronal viability, and functional magnetic resonance imaging (fMRI), which provides assessment of localized blood oxygenation state association with performance of specific cognitive or motor tasks. Here, we first review postmortem observations on patients with HIV infection and with alcoholism to identify the cell types and brain regions most affected by the end stage of the disease. We then review in vivo neuroimaging studies of brain changes associated with HIV infection, chronic alcohol use, their interaction, and the potentiating effects of age. While there are many studies of people with either HIV infection or chronic alcohol use alone currently little has been published on the interactive effects of these variables, despite the high prevalence of overlap. We conclude with a consideration of the methodological issues such studies must address.

Acquired Immunodeficiency Syndrome↗
PubMed2006

Functional interactions between entorhinal cortex and posterior cingulate cortex at the very early stage of Alzheimer's disease using brain perfusion single-photon emission computed tomography.

OBJECTIVE: The cause of the reduced regional cerebral blood flow (rCBF) in the posterior cingulate cortex in the early stage of Alzheimer's disease has not been clarified. In Alzheimer's disease, the posterior cingulate cortex itself shows little neuropathologic degeneration, and a hypothesis explaining such a discrepancy is that the functional impairment in the posterior cingulate cortex reflects remote effects caused by degeneration in distant but connected areas, such as the entorhinal cortex. To test the hypothesis, we investigated the functional connectivity between the entorhinal cortex and posterior cingulate cortex. METHODS: Sixty-one patients with probable Alzheimer's disease at a very early stage and 61 age-matched healthy controls underwent both brain structural magnetic resonance imaging (MRI) and single-photon emission computed tomography (SPECT). Voxel-based morphometry was performed on MRI data to identify clusters of significantly reduced grey matter concentration in patients with Alzheimer's disease relative to controls, which were set as volumes of interest (VOIs) for correlation analyses of SPECT images. We then used adjusted rCBF values in the VOIs as covariates of interest in statistical parametric mapping. RESULTS: Voxel-based morphometry demonstrated a significant reduction in grey matter concentration in the bilateral entorhinal cortex in Alzheimer's disease. A positive correlation between rCBF in the entorhinal cortex as VOI and that in the limbic and paralimbic systems, including the posterior cingulate cortex, anterior cingulate cortex, lingual gyri and left middle temporal gyrus (P<0.001), was observed in Alzheimer's disease. Control subjects also showed a similar correlation in the limbic and paralimbic systems, but not in the posterior cingulate cortex. CONCLUSION: These results indicate that rCBF changes in the posterior cingulate cortex may be closely related to those in the entorhinal cortex in patients with Alzheimer's disease, thereby supporting the 'remote effect' hypothesis.

Aged↗
PubMed1999

Global, voxel, and cluster tests, by theory and permutation, for a difference between two groups of structural MR images of the brain.

We describe almost entirely automated procedures for estimation of global, voxel, and cluster-level statistics to test the null hypothesis of zero neuroanatomical difference between two groups of structural magnetic resonance imaging (MRI) data. Theoretical distributions under the null hypothesis are available for 1) global tissue class volumes; 2) standardized linear model [analysis of variance (ANOVA and ANCOVA)] coefficients estimated at each voxel; and 3) an area of spatially connected clusters generated by applying an arbitrary threshold to a two-dimensional (2-D) map of normal statistics at voxel level. We describe novel methods for economically ascertaining probability distributions under the null hypothesis, with fewer assumptions, by permutation of the observed data. Nominal Type I error control by permutation testing is generally excellent; whereas theoretical distributions may be over conservative. Permutation has the additional advantage that it can be used to test any statistic of interest, such as the sum of suprathreshold voxel statistics in a cluster (or cluster mass), regardless of its theoretical tractability under the null hypothesis. These issues are illustrated by application to MRI data acquired from 18 adolescents with hyperkinetic disorder and 16 control subjects matched for age and gender.

Adolescent↗
PubMed1995

A case of Gartner's duct cyst with a right aplastic kidney.

We report a case of a Gartner's duct cyst with a right aplastic kidney. This was discovered when the right kidney was not identified in an examination for epigastric pain. CT and MRI proved useful in the diagnosis. An MRI showed a tubular structure ascending from the cyst and a complication of a bicornate uterus. As the patient was asymptomatic, the patient was followed without treatment.

Child↗
PubMed1993

Anaerobic orbital abscess secondary to intraorbital wood.

A case of anaerobic orbital cellulitis secondary to intraorbital wood and an approach to management are presented. Retained foreign bodies should be suspected in all penetrating orbital injuries involving wood. Computed tomography (CT) should be performed to delineate the location and size of any foreign body and to determine damage to adjacent structures. Magnetic resonance imaging (MRI) is useful in certain circumstances. Orbital infection should be anticipated and broad-spectrum antibiotic cover (including anaerobes) provided. Surgical intervention should be undertaken to remove any retained foreign bodies to prevent vision-threatening complications.

Abscess↗
PubMed2000

The clinical usefulness of ictal surface EEG in neocortical epilepsy.

PURPOSE: Localizable scalp EEGs, during ictal episodes, appear to be rare in neocortical epileptic syndromes. However, studies based on large numbers of patients are also rare. This study aims to identify the characteristic patterns of variable neocortical epilepsies and to evaluate their clinical usefulness in the localization of epileptogenic focuses. METHODS: We retrospectively assessed 394 noninvasive ictal recordings from 86 patients who subsequently underwent invasive study and resective surgery. Ictal EEGs were recorded using a video-EEG monitoring system with electrodes placed according to the International 10-20 system, with additional anterior temporal electrodes. The ictal recordings were analyzed according to localizing accuracy and frequency characteristics. The durations of discrete or regional ictal rhythms were also measured. RESULTS: The percentage of discrete or regional EEGs was 23% in frontal lobe epilepsy, 52% in lateral temporal lobe epilepsy, 70% in occipital lobe epilepsy, and 10% in parietal lobe epilepsy. In order of frequency, the localizable ictal rhythms were theta, beta, alpha, delta, and rhythmic spike-and-wave. The duration of discrete or regional ictal rhythms was significantly shorter in frontal lobe epilepsy and parietal lobe epilepsy than in other epilepsies. Ictal beta activity was the most common rhythm in discrete-patterned EEGs. Structural lesions found on MRI did not significantly affect the localization of epileptogenic focuses in the patients. The type of seizure was not related to the degree of localization, with the exception of simple partial seizure. CONCLUSIONS: Ictal surface EEG was clinically helpful in the localization of epileptogenic focuses in at least some neocortical epileptic syndromes.

Adult↗