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At least 1,315 records · Page 73Linked to original sources
PubMed1997

Positron emission tomography in children with neurofibromatosis-1.

Neurofibromatosis-1 is an autosomal dominant genetic disorder commonly associated with neuropsychological complications. Focal areas of high signal intensity on magnetic resonance imaging (MRI) scans occur commonly but have shown inconsistent correlation with neuropsychological problems. Positron emission tomography (PET) scans utilizing [18F]fluoro-2-deoxy-D-glucose and MRI studies were performed on 10 children with neurofibromatosis-1 and multiple focal areas of high signal intensity to evaluate the regional cerebral metabolic rate for glucose of these lesions and other central nervous system structures. Co-registered PET and MRI studies confirmed reduced glucose metabolism of large focal areas of high signal intensity. Visual inspection and semiquantitative analysis of PET images demonstrated thalamic hypometabolism and varying degrees of cortical inhomogeneity in all cases of neurofibromatosis-1 compared to normal controls. Although a primary defect of the thalamus or cerebral cortex has not been defined, the metabolic abnormalities of this study suggest a potential relationship between these structures and the neuropsychological dysfunctions noted in neurofibromatosis-1.

Adolescent↗
PubMed1998

NMR studies of salivary glands: from energy metabolism to morphology.

Nuclear magnetic resonance (NMR) spectroscopy has been used to study various physiological functions of salivary glands. This short review summarizes results on energy metabolism and acid-base balance (31P and 14N NMR), electrolytes transport (23Na, 39K, 35Cl and 87Rb NMR) and water transport (1H NMR). The latest development of 1H nuclear magnetic resonance imaging (MRI) allows the three-dimensional structure of salivary glands to be observed with ca. 60 microm resolution, and it is also possible to observe circulation, flow, and volume changes during secretion. The combination of NMR and MRI may open up new fields in the study of exocrine secretion.

Acid-Base Equilibrium↗
PubMed1998

The suspensory ligament of the penis: an anatomic and radiologic description.

The suspensory system of the penis acquires clinical importance in reparative surgery, traumatology and through its role in erection. The aim of this study was to identify the different anatomic structures constituting the suspensory ligament by dissection and by magnetic resonance imaging (MRI). Ten unembalmed male subjects were used for dissection of the region of the base of the penis. Ten volunteer patients underwent MRI of the penis before and after the injection of prostaglandin (PGE1). The suspensory apparatus consisted of separate ligamentous structures: the fundiform ligament, which is lateral, superficial and not adherent to the tunica albuginea of the corpora cavernosa; the suspensory ligament properly so-called, further back, stretching between the pubis and the tunica albuginea of the corpora cavernosa and consisting of two lateral, circumferential, and one median bundles, which circumscribed the dorsal vein of the penis. These structures were identifiable in MRI and their supporting role was evidenced during tests of erection. The suspensory ligament seemed to maintain the base of the penis in front of the pubis and to behave as a major point of support for the mobile portion of the penis during erection.

Aged↗
PubMed1990

Notes from the graveyard: neuropathology and schizophrenia.

Schizophrenia is commonly regarded as a 'functional' psychosis, the implication being that the delusions, hallucinations and cognitive impairment characteristic of the disease have no organic basis. This view is due in no small way to the failure of pathologists to find convincing pathological changes associated with the disease in the first seven decades of the century. Over the last 10 years things have changed considerably. Recent CT and MRI scan studies have provided convincing evidence of significant ventricular enlargement in the brains of schizophrenics and post-mortem studies have shown that schizophrenic brains are about 6% lighter than controls and have a reduced volume and reduced antero-posterior length. Planimetric studies on post-mortem material and a recent MRI study show that medial temporal lobe structures (parahippocampal gyrus, hippocampus and amygdala) are preferentially affected. Although other brain regions (e.g. cingulate gyrus, frontal cortex) also show alterations they appear to be 'downstream' from the regions primarily affected. Morphological studies show that there is a loss of neurons from medial temporal lobe structures and indicate irregularities in their cytoarchitectonic arrangement. The alterations in structure are not associated with degenerative, inflammatory, or abnormal vascular processes. There has been much debate as to the possible causes of the structural changes and whether they are limited to particular 'types' or sub-groups of schizophrenics. At present it seems simpler to suppose that all schizophrenics have a degree of structural abnormality which may differ in degree but not in kind. It has been proposed that the changes in brain structure in schizophrenia are the result of an anomaly of brain development. In the last year CT and MRI studies have shown that ventricular enlargement precedes clinical symptoms and is not progressive. These studies support the developmental interpretation. Future studies will need to focus on (a) the mechanisms (probably genetic) which can cause such developmental anomalies, (b) the neurochemical perturbations occurring as a result of such anomalies and (c) how both relate to clinical symptoms.

Brain↗
PubMed2006

The state of the art of fetal magnetic resonance imaging.

OBJECTIVE: To assess the state of the art of fetal magnetic resonance imaging (MRI) in China. DATA SOURCES: Both Chinese and English language literatures were searched in the databases of PUBMED (1998-2005) and CNKI (1998-2005), 41 published articles about fetal MRI were selected. RESULTS: Fetal MRI can serve as an adjunct tool for ultrasonography because of its excellent soft tissue contrast, high spatial resolution, multiplanar capabilities, large field of view and simultaneous visualization of fetal and maternal structures. Since the development of ultrafast MRI sequences provides faster scan time and avoids motion artifacts, it is widely applied in detecting normal or abnormal fetal development, including the central nervous system, thoracic region, abdomen and others. In China, experience in fetal MRI has been scanty, but the technique will be extensively used in the near future because of its multi-faceted advantages. CONCLUSIONS: Compared with ultrasonography, MRI as a complementary imaging for fetal screening is prospective in China or other parts of the world because of its multiple superiorities.

Abdomen↗
PubMed1994

[Magnetic resonance in the pathologic evaluation of the isolated human brain].

The purpose of this study was to evaluate the interest of MRI of excised human brains before traditional pathological examination. MRI was performed on 40 formalin fixed brain specimen; the brains were placed on tap water in a plastic box, and submitted to standard MRI, 3D FT volume acquisition and multislice SE T1, PD and T2 weighted. The results of 3D FT volume acquisition were used for multiplanar reconstruction of planes according to the direction of anatomical structures. Our experience demonstrate that preliminary MRI of excised brains is possible because it does not alternate the results of following standard pathological examinations; the dissection may be focused on the MRI demonstrated pathology. MRI allows to correlate the results of the pathological examination of a slice with the state of the whole brain. An interesting option is the use of this method for medico-legal purpose.

Brain↗
PubMed1988

Comparison of MRI and CT scans in a group of psychiatric patients.

The authors compared the results of computerized tomography (CT) and magnetic resonance imaging (MRI) scans of 16 psychotic patients with various diagnoses whose neurologic examinations suggested structural brain abnormalities. Blind readings showed a high concordance of findings, including ventricle-to-brain ratios, although MRI appeared superior in visualizing midline structures and identifying atrophic changes. Because it requires no ionizing radiation, MRI allows multiple studies of the same patient, study of family members, and recruitment of unbiased samples of control subjects. Use of MRI may help address questions regarding the specificity and prevalence of brain abnormalities observed with CT in psychotic patients.

Adolescent↗
PubMed1994

MRI of a silicone breast implant surrounded by an enlarging hemorrhagic collection.

MRI yields cross-sectional image acquisition in multiple planes with very high contrast resolution. Additionally, in MRI of the breast, evaluation of the entire implant is possible. Not only is MRI very sensitive to loss of implant integrity and rupture, but also MRI can evaluate and characterize adjacent fluid collections or soft-tissue masses. Anatomic relationships of abnormalities and normal structures are well seen. In some situations, MRI may offer clinically relevant information not adequately addressed by other imaging modalities.

Breast↗
PubMed2000

Quantitative MRI of the hippocampus and amygdala in severe depression.

BACKGROUND: There is little evidence to support possible structural changes in the amygdala and hippocampus of patients with severe depression. METHODS: Quantitative MRI of the amygdala and hippocampus, as well as proton spectroscopy (MRS) of mesial temporal structures were studied in 34 drug-resistant in-patients with major depression and compared with 17 age-matched controls. Volumetric MRI data were normalized for brain size. RESULTS: The volume of the left hippocampus was significantly smaller in the patients compared with the controls. Both groups exhibited similar significant hippocampal asymmetry (left smaller than right). The patients, but not the controls, had significant asymmetry of the amygdalar volumes (right smaller than left). No differences were observed between the patients and controls in the T2 relaxation times for the hippocampus and amygdala. Mesial temporal lobe MRS revealed a significantly elevated choline/creatine ratio in the patients compared with the controls. CONCLUSIONS: This quantitative MRI study provides support for a possible association between structural and biochemical substrates and severe drug-resistant major depression.

Adult↗
PubMed1995

The effect of white matter hyperintensity volume on brain structure, cognitive performance, and cerebral metabolism of glucose in 51 healthy adults.

OBJECTIVE: To assess the association of MRI white matter hyperintensities (WMHI) with cognitive performance, cerebral structure, and cerebral metabolism in 51 healthy individuals aged 19 to 91 years without cerebrovascular risk factors. BACKGROUND: Abnormal white matter signals have been associated with brain atrophy, reduced cerebral blood flow, focal neurologic signs, gait disorder, and poorer neuropsychological test performance. Most studies of WMHI, however, include subjects with hypertension or other identifiable causes of cerebrovascular disease that may have an independent effect on brain structure and function. To assess brain changes associated with WMHI independent of cerebrovascular risk factors, we determined WMHI volume, brain volume, cerebral metabolism, and cognitive performance for a group of subjects free of medical illness. Regional cerebral metabolism and cognitive domains were also assessed to evaluate the possible role of frontal lobe dysfunction in subjects with WMHI. DESIGN: Cross-sectional study of 51 very healthy subjects aged 19 to 91 years. METHODS: WMHI, brain, and CSF volumes were determined by MRI segmentation. Neuropsychological tests were employed to assess multiple cognitive domains. Brain metabolism was determined from 18-fluoro-2-deoxy-D-glucose PET. Multivariate relations were tested with stepwise linear regression. Models included the potential confounders of age and education where appropriate. RESULTS: The distribution of WMHI volume was bimodal, with five subjects having WMHI volumes beyond three SDs from the normally distributed population. A WMHI volume of greater than 0.5% of intracranial volume was considered abnormal. Within the multivariate models, WMHI volumes were significantly predictive of increased ventricular volume, reduced brain volume, and reduced cognitive scores. Subjects with greater than 0.5% WMHI volume also had significantly lower frontal lobe metabolism, significantly higher systolic blood pressure, significantly larger ventricular volume, and significantly lower scores on frontal lobe-mediated neuropsychological tests than age-matched controls. CONCLUSION: WMHI volume is associated with structural and functional brain changes even within a group of very healthy individuals. WMHI is associated with poorer frontal lobe cognitive function and, when severe, is accompanied by significantly reduced frontal lobe metabolism. Subjects with large WMHI volumes have significantly higher systolic blood pressure, brain atrophy, reduced cerebral metabolism, and lower scores on tests of frontal lobe function than age-matched controls. Large amounts of WMHI are, therefore, pathologic and may be related to elevated systolic blood pressure even when it is within the normal age-related range.

Adult↗
PubMed1994

MRI of trauma and sports-related injuries of tendons and ligaments. Part I: Spine and upper extremities.

MRI is valuable in evaluation of tendons and ligaments in sports-related injuries. Tendons and ligaments show dark signal intensity on all MR sequences. Alteration in size, shape, continuity, and signal intensity of these structures can be well visualized with MRI. Impingement syndrome is the leading cause of atrophy and degeneration of the rotator cuff. Shape of the acromion, presence of subacromial spur, and involvement in certain sport activities that lead to shoulder instability may cause impingement of the rotator cuff. This article systematically reviews the injuries of tendons and ligaments in the spine, shoulder, elbow, wrist, and hand.

Adult↗
PubMed2004

Geometric strategies for neuroanatomic analysis from MRI.

In this paper, we describe ongoing work in the Image Processing and Analysis Group (IPAG) at Yale University specifically aimed at the analysis of structural information as represented within magnetic resonance images (MRI) of the human brain. Specifically, we will describe our applied mathematical approaches to the segmentation of cortical and subcortical structure, the analysis of white matter fiber tracks using diffusion tensor imaging (DTI), and the intersubject registration of neuroanatomical (aMRI) data sets. Many of our methods rally around the use of geometric constraints, statistical (MAP) estimation, and the use of level set evolution strategies. The analysis of gray matter structure and connecting white matter paths combined with the ability to bring all information into a common space via intersubject registration should provide us with a rich set of data to investigate structure and variation in the human brain in neuropsychiatric disorders, as well as provide a basis for current work in the development of integrated brain function-structure analysis.

Algorithms↗
PubMed2004

Measurement of myocardial mechanics in mice before and after infarction using multislice displacement-encoded MRI with 3D motion encoding.

Cardiac MRI is an accurate, noninvasive modality for assessing the structure and function of the murine heart. In addition to conventional imaging, MRI tissue tracking methods can quantify numerous aspects of myocardial mechanics, including intramyocardial displacement, strain, twist, and torsion. In the present study, we developed and applied a novel pulse sequence based on displacement-encoded imaging using stimulated echoes (DENSE) that achieves multislice coverage, high spatial resolution, and three-dimensional (3D) displacement encoding. With the use of this technique, myocardial mechanics of C57Bl/6 mice were measured at baseline and 1 day after experimental myocardial infarction. At baseline, the mean systolic transmural circumferential strain was -0.14 +/- 0.02 and the mean systolic radial strain was 0.30 +/- 0.05. Changes in circumferential and radial strains from the subepicardium to the subendocardium were detected at baseline (P < 0.05). One day after infarction, significantly reduced 3D displacements and strain were detected in infarcted and noninfarcted myocardium. Infarction also reduced normalized systolic torsion from its baseline value of 1.35 +/- 0.27 degrees /mm (R = 0.99) to 0.07 +/- 0.54 degrees /mm (R = 0.96, P < 0.05). DENSE MRI can assess the 3D myocardial mechanics of the murine heart in <1 h of scan time at 4.7 T and may be applied to studies of myocardial mechanics in genetically engineered mice.

Animals↗
PubMed2005

[New challenges in multiple sclerosis].

After decades of prevailing fatalism concerning multiple sclerosis new hopes emerge at the horizon of both the diagnostic and therapeutic section catalyzed by a new understanding of the neurodegenerative disease process. The rapidly evolving MRI techniques enabled an analysis of CNS tissue injury in terms of structure and chemical composition. Based on studies with serial MRI scans, multiple sclerosis is increasingly considered as a dynamic disease process, in which not only the myelin but also the axons are damaged already in a very early stage. The introduction of interferon therapy caused much attention and great hope both among patients and clinicians. Unfortunately clinical studies require a large number of patients and long periods. Obviously if treated early enough and consistently, patients with the relapsing-remitting form of multiple sclerosis suffer less exacerbations, MRI lesions and disease progression in comparison to patients not treated by interferons. But sustained improvement in terms of extramortality and extramorbidity can only be expected in the medium term.

Germany↗
PubMed2005

Structural abnormality on brain magnetic resonance imaging in late-onset major depressive disorder.

The purpose of this study was to examine the structural abnormalities of patients with late-onset major depressive disorder using brain magnetic resonance imaging (MRI) and to assess clinical correlates of these structural abnormalities. Thirty-seven elderly patients with DSM-IV major depressive disorder that first occurred after the age of 50 years, and 18 control subjects without depression were recruited. All participants underwent comprehensive psychiatric assessment and cerebral MRI. Brain ventricular and sulcal sizes and white matter hyperintensities were assessed visually. Relative to control subjects, patients with late-life major depressive disorder showed more severe brain atrophy (p = 0.043) and white matter hyperintensities (p = 0.024), especially in the periventricular area (p = 0.012). Over 60% of the patient group had significant brain MRI hyperintensities. White matter hyperintensity was correlated with later onset of depressive illness (r = 0.49, p = 0.002) among patients. Brain atrophy and white matter hyperintensities are prevalent in patients with late-onset major depressive disorders. These two abnormalities may represent different pathophysiologic processes of depressive disorders. White matter hyperintensities may be predisposing factors for late-onset major depressive disorder.

Aged↗
PubMed2004

In vivo structural imaging of the rat brain with a 3-T clinical human scanner.

PURPOSE: To examine the feasibility of using product acquisition software on a 3-T human MRI system to acquire high-resolution structural brain images in the rat. MATERIALS AND METHODS: Three sets of dual spin-echo, high-resolution (0.234 x 0.234 mm in-plane, 0.5 mm thick) images covering the entire rat brain were collected and averaged in 66 min. The images had sufficient signal-to-noise ratio (SNR) and resolution for visual identification and manual outlining of exemplary structures, including the lateral ventricles and dorsal and ventral portions of the hippocampus. Further, the data were adequate for unsupervised, automated segmentation, permitting quantification of the dorsolateral ventricles. The images compared favorably with those collected on a 7-T system. RESULTS: Interrater reliabilities (intraclass correlations) of manual ventricular scoring were greater than 0.97, and manual vs. automated correlations were 0.97. The variability of lateral ventricular size across animals was substantially higher than that of the hippocampus. CONCLUSION: The large variability of some brain structures that can exist across even a highly selected strain of rats can readily be detected with the use of human 3-T systems for the study of small animals.

Animals↗
PubMed2004

The relationship between disc degeneration and morphologic changes in the intervertebral foramen of the cervical spine: a cadaveric MRI and CT study.

A cadaveric study was performed to investigate the relationship between disc degeneration and morphological changes in the intervertebral foramen of cervical spine, including the effect on the nerve root. Seven fresh frozen human cadavers were dissected from C1 to T1, preserving the ligaments, capsules, intervertebral disc and the neural structures. The specimens were scanned with MRI and then scanned through CT scan in the upright position. Direct mid-sagittal and 45 degree oblique images were obtained to measure the dimension of the intervertebral disc height, foraminal height, width, area and segmental angles. Disc degeneration was inversely correlated with disc height. There was a significant correlation between disc degeneration and foraminal width (p<0.005) and foraminal area (p< 0.05), but not with foraminal height. Disc height was correlated with foraminal width but not with height. The segmental angles were decreased more in advanced degenerated discs. There was a correlation between nerve root compression and decreased foraminal width and area (p<0.005). This information and critical dimensions of the intervertebral foramen for nerve root compression should help in the diagnosis of foraminal stenosis of the cervical spine in patients presenting with cervical spondylosis and radiculopathy.

Adult↗
PubMed2006

Reproducibility of foot structure measurements in neuropathic diabetic patients using magnetic resonance imaging.

PURPOSE: To assess the intra- and interobserver agreement of commonly reported foot structure measurements in diabetic patients with neuropathy using magnetic resonance imaging (MRI). MATERIALS AND METHODS: In 23 neuropathic diabetic patients and five age-matched healthy controls, sagittal-plane MR images of the forefoot were obtained to assess joint configuration and plantar fat-pad thickness on two different occasions by the same observer and once by a different observer. The degree of intrinsic muscle atrophy was scored from coronal plane images on two different occasions by two observers. RESULTS: The intraclass correlation coefficients (ICCs) between occasions and between observers were >0.94. The mean differences (bias) and the limits of agreement (LoA = mean +/- 2 SDs) were small for the metatarsal-phalangeal (MTP) joint angle, toe angle, and plantar fat-pad thickness (bias </= 0.8 degrees or 0.2 mm, LoA </= 3.8 degrees or 0.8 mm), but larger for interphalangeal joint angles (bias </= 3.4 degrees , LoA </= 8.8 degrees). The weighted kappa for intrinsic muscle atrophy was 0.94. CONCLUSION: Static foot structure data can be assessed reliably using MRI. Because changes in foot structure contribute to the development of foot ulcers in neuropathic patients, MRI may be a useful technique to assess risk of ulceration in these patients.

Aged↗