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PubMedDate not supplied

[Neuropsychological consequences of perinatal asphyxia].

Perinatal asphyxia has been classically related to important neurological diseases such as cerebral palsy, but it it also stated that a high percentage of child with a good outcome did not show any sequelae. We reviewed cerebral lesions demonstrated by post-mortem analysis and the structural MRI contributions to the anatomo-functional correlates. The most frequent neuropsychological disturbances showed by these patients in the general intelligence, perceptive functions, memory and emotional and social behavior were also summarized.

Asphyxia Neonatorum↗
PubMed1998

[Progressive aphasia without dementia].

INTRODUCTION: Slowly progressive aphasia without generalized dementia is considered as a degenerative disorder that can be differentiated of others well-known neurodegenerative disorders. CLINICAL CASE: We present a case report of a patient with slowly progressive aphasia, characterized by a progressive anomia and without generalized dementia. The patient was evaluated in the last four years: a neuropsychological assessment, a neurological exploration and structural (MRI) and functional (SPECT) neuroimaging were performed. CONCLUSION: This case is interesting on account of a selective implication of the left temporal hemisphere is showed in the pathogenesis of this disorder.

Anomia↗
PubMed1995

Use of MRI for measuring structures in frozen postmortem brain.

A method was developed for magnetic resonance imaging (MRI) of human autopsy brains stored long-term at -70 degrees C. Scanning brains at temperatures between -70 and -8 degrees C gave minimal MRI signals consistent with protons having limited freedom of movement at low temperature. Raising brain temperature improved the signal such that scanning at -1 degree C generated images with good in-plane resolution, grey/white matter contrast, and fine detail of cortical sulcal/gyral patterns. To validate the method, volume and area measurements were made using computerized image analysis on stored digital images of 14 brains from adult subjects of both genders and various ages. The data confirmed that brain volume was inversely correlated with age, and female subjects had smaller brains. This is a valuable new method for acquiring morphometric data from previously unscanned pathologic brains that are to be used for neurochemical and molecular investigations.

Analysis of Variance↗
PubMed1999

MRI anatomy of schizophrenia.

Structural magnetic resonance imaging (MRI) data have provided much evidence in support of our current view that schizophrenia is a brain disorder with altered brain structure, and consequently involving more than a simple disturbance in neurotransmission. This review surveys 118 peer-reviewed studies with control group from 1987 to May 1998. Most studies (81%) do not find abnormalities of whole brain/intracranial contents, while lateral ventricle enlargement is reported in 77%, and third ventricle enlargement in 67%. The temporal lobe was the brain parenchymal region with the most consistently documented abnormalities. Volume decreases were found in 62% of 37 studies of whole temporal lobe, and in 81% of 16 studies of the superior temporal gyrus (and in 100% with gray matter separately evaluated). Fully 77% of the 30 studies of the medial temporal lobe reported volume reduction in one or more of its constituent structures (hippocampus, amygdala, parahippocampal gyrus). Despite evidence for frontal lobe functional abnormalities, structural MRI investigations less consistently found abnormalities, with 55% describing volume reduction. It may be that frontal lobe volume changes are small, and near the threshold for MRI detection. The parietal and occipital lobes were much less studied; about half of the studies showed positive findings. Most studies of cortical gray matter (86%) found volume reductions were not diffuse, but more pronounced in certain areas. About two thirds of the studies of subcortical structures of thalamus, corpus callosum and basal ganglia (which tend to increase volume with typical neuroleptics), show positive findings, as do almost all (91%) studies of cavum septi pellucidi (CSP). Most data were consistent with a developmental model, but growing evidence was compatible also with progressive, neurodegenerative features, suggesting a "two-hit" model of schizophrenia, for which a cellular hypothesis is discussed. The relationship of clinical symptoms to MRI findings is reviewed, as is the growing evidence suggesting structural abnormalities differ in affective (bipolar) psychosis and schizophrenia.

Brain↗
PubMedDate not supplied

Assessment of posterior fossa structures with midsagittal MRI: the effects of age.

Midsagittal magnetic resonance (MR) images of 36 normal volunteers, ranging in age from 26 to 79 years, were used to evaluate the effects of age on the size of posterior fossa structures (cerebellar vermis, midbrain, pons, medulla and fourth ventricle). Our results demonstrate a highly statistically significant age-related decline in the cross-sectional area of the midbrain (r = -.44, p less than 0.007), a less prominent decline in the area of the anterior cerebellar vermis (r = -.33, p less than 0.05) and striking intercorrelations between the dimensions of the pons, medulla and cerebellar vermis. To the best of our knowledge, this is the first MRI demonstration of midbrain atrophy during aging in normal adults.

Adult↗
PubMed2002

(18)F-FDG PET in localization of frontal lobe epilepsy: comparison of visual and SPM analysis.

UNLABELLED: The sensitivity of (18)F-FDG PET to localize epileptogenic zones in frontal lobe epilepsy was evaluated by both visual assessment and statistical parametric mapping (SPM). METHODS: Twenty-nine patients with frontal lobe epilepsy were examined. All patients showed good outcome after surgical resection (Engel class I or II). On pathologic examination, 22 patients had cortical dysplasia, 4 had tumors, 1 had cortical scars, and 2 had an old infarct. Hypometabolic lesions were found on (18)F-FDG PET images by both visual assessment and SPM analysis. On SPM analysis, the cutoff threshold was varied and sensitivity to find epileptogenic zones was compared. RESULTS: MRI showed structural lesions in 15 patients and normal findings in 14. (18)F-FDG PET correctly localized the epileptogenic zones in 16 patients (55%) by visual assessment. The sensitivity of (18)F-FDG PET was 36% in patients without structural lesions on MRI and 73% in patients with structural lesions. On SPM analysis, using an uncorrected probability value of 0.005 as the threshold, the sensitivity of SPM analysis was 66%, which was not statistically different from the sensitivity of visual assessment. The sensitivity decreased according to the decrease in probability value. CONCLUSION: (18)F-FDG PET was sensitive in localizing epileptogenic zones by revealing hypometabolic areas in nonlesional patients with frontal lobe epilepsy as well as in lesional patients. SPM analysis showed a comparable sensitivity to visual assessment and could be used as an aid in diagnosing epileptogenic zones in frontal lobe epilepsy.

Adult↗
PubMed2003

Corticobasal degeneration: structural and functional MRI and single-photon emission computed tomography.

We studied seven patients with corticobasal degeneration (CBD) from a clinical and imaging perspective. We describe the main morphological features of CBD and, using functional MRI, try to define the possible role of the parietal lobe in simple and complex learned motor sequences. We showed decreased activation of the parietal lobe contralateral to the more affected arm, when movements, simple or complex, are performed with that hand. Moreover we found that functional imaging can demonstrate parietal and motor cortex dysfunction before structural, and even single-photon emission computed tomography changes become evident.

Aged↗
PubMed2004

Verbal episodic memory impairment in Alzheimer's disease: a combined structural and functional MRI study.

Anatomical and functional MRI images were acquired in a group of healthy elderly subjects (n = 11) and a group of patients diagnosed with probable Alzheimer's disease, from mild to moderate severity (n = 8). During functional sessions, verbal episodic Encoding and Recognition tasks were presented to subjects. Both groups were compared in terms of gray matter volume and cerebral activation. Furthermore, in the AD group, correlations between hippocampal gray matter volume and whole-brain activations were examined. When compared to healthy controls, AD patients presented significant gray matter atrophy as well as reduced activations during Encoding and Recognition in the medial temporal lobes and inferior parietal/superior temporal associative areas. In the same regions, the fMRI activity elicited by the Recognition task was positively correlated with hippocampal gray matter volume. Moreover, an increase of left prefrontal activity during Encoding and Recognition was observed in AD patients relative to controls and was correlated with memory performance. This additional activity elicited by episodic memory processes was not found to correlate with the degree of medial temporal atrophy in our group of patients. Our study shows that function in brain regions critical to episodic memory is altered in AD. During episodic Recognition, these functional changes may closely correlate with the progressive structural changes observed in the hippocampal region.

Aged↗
PubMed2001

Unfolding the human hippocampus with high resolution structural and functional MRI.

The hippocampus is a region of the brain that is crucial to memory function. Functional neuroimaging allows for the noninvasive investigation of the neurophysiology of human memory by observing changes in blood flow in the brain. We have developed a technique that employs high-resolution functional magnetic resonance imaging (fMRI) in combination with cortical unfolding to provide activation maps of the hippocampal region that surpass in anatomic and functional detail other methods of in vivo human brain mapping of the medial temporal lobe. We explain the principles behind this method and illustrate its application to a novelty-encoding paradigm.

Brain Mapping↗
PubMed2005

The clinical utility of structural neuroimaging with MRI for diagnosis and differential diagnosis of dementia: a memory clinic study.

OBJECTIVES: The individual contribution to the final comprehensive clinical diagnosis of neuropsychology (NP) and magnetic resonance imaging (MRI), respectively, was quantified in a specialized tertiary care setting to investigate the added clinical value of routine MRI. METHODS: In 106 patients referred to a university memory clinic for the work-up of cognitive disturbances the primary care diagnosis, the initial clinical neuropsychiatric diagnosis, the neuropsychological and MRI diagnoses, and the final comprehensive clinical diagnosis were documented. The neuropsychological investigation was performed using the CERAD test battery. MRI was performed using T1, double echo and FLAIR sequences without contrast medium. The change of the final comprehensive clinical diagnosis in relation to the initial neuropsychiatric diagnosis was used to determine the diagnostic contribution of both, MRI and NP. RESULTS: NP and MRI led to a significant change of the final comprehensive diagnosis in 26% of patients (CI: 0.26 +/- 0.09; p < 0.05). In addition, three cases of secondary dementias, and six cases of vascular encephalopathy without dementia were recognized by MRI. Sensitivity, specificity, and the positive predictive value were higher for NP and MRI, respectively, than for the initial clinical diagnosis alone. CONCLUSION: MRI as well as neuropsychological testing improves early detection and differential diagnosis of dementia and additionally supplies clinically relevant findings. MRI carries added clinical value in the investigation of dementias.

Aged↗
PubMed2003

A framework for a streamline-based probabilistic index of connectivity (PICo) using a structural interpretation of MRI diffusion measurements.

PURPOSE: To establish a general methodology for quantifying streamline-based diffusion fiber tracking methods in terms of probability of connection between points and/or regions. MATERIALS AND METHODS: The commonly used streamline approach is adapted to exploit the uncertainty in the orientation of the principal direction of diffusion defined for each image voxel. Running the streamline process repeatedly using Monte Carlo methods to exploit this inherent uncertainty generates maps of connection probability. Uncertainty is defined by interpreting the shape of the diffusion orientation profile provided by the diffusion tensor in terms of the underlying microstructure. RESULTS: Two candidates for describing the uncertainty in the diffusion tensor are proposed and maps of probability of connection to chosen start points or regions are generated in a number of major tracts. CONCLUSION: The methods presented provide a generic framework for utilizing streamline methods to generate probabilistic maps of connectivity.

Anisotropy↗
PubMed2005

Simultaneous registration and segmentation of anatomical structures from brain MRI.

In this paper, we present a novel variational formulation of the registration assisted image segmentation problem which leads to solving a coupled set of nonlinear PDEs that are solved using efficient numerical schemes. Our work is a departure from earlier methods in that we have a unified variational principle wherein non-rigid registration and segmentation are simultaneously achieved; unlike previous methods of solution for this problem, our algorithm can accommodate for image pairs having very distinct intensity distributions. We present examples of performance of our algorithm on synthetic and real data sets along with quantitative accuracy estimates of the registration.

Algorithms↗
PubMed2003

Type 2 diabetes and atrophy of medial temporal lobe structures on brain MRI.

AIM/HYPOTHESIS: Type 2 diabetes increases the risk not only of vascular dementia but also of Alzheimer's disease. The question remains whether diabetes increases the risk of Alzheimer's disease by diabetic vasculopathy or whether diabetes influences directly the development of Alzheimer neuropathology. In vivo, hippocampal and amygdalar atrophy on brain MRI are good, early markers of the degree of Alzheimer neuropathology. We investigated the association between diabetes mellitus, insulin resistance and the degree of hippocampal and amygdalar atrophy on magnetic resonance imaging (MRI) accounting for vascular pathology. METHODS: Data was obtained in a population-based study of elderly subjects without dementia between 60 to 90 years of age. The presence of diabetes mellitus and, in non-diabetic subjects, insulin resistance was assessed for 506 participants in whom hippocampal and amygdalar volumes on MRI were measured. We assessed the degree of vascular morbidity by rating carotid atherosclerosis, and brain white matter lesions and infarcts on MRI. RESULTS: Subjects with diabetes mellitus had more hippocampal and amygdalar atrophy on MRI compared to subjects without diabetes mellitus. Furthermore, increasing insulin resistance was associated with more amygdalar atrophy on MRI. The associations were not due to vascular morbidity being more pronounced in persons with diabetes mellitus. CONCLUSIONS/INTERPRETATION: Type 2 diabetes is associated with hippocampal and amygdalar atrophy, regardless of vascular pathology. This could suggest that Type 2 diabetes directly influences the development of Alzheimer neuropathology.

Aged↗
PubMed2001

Does the trabecular bone structure depicted by high-resolution MRI of the calcaneus reflect the true bone structure?

RATIONALE AND OBJECTIVES: The purpose of this study was to compare trabecular bone structure parameters assessed with high-resolution magnetic resonance imaging (HR-MRI) with those determined in specimen sections. METHODS: High-resolution MR images were obtained for 30 calcaneus specimens with a three-dimensional, T1-weighted spin-echo sequence (spatial in-plane resolution 0.195 mm, slice thicknesses of 0.3 and 0.9 mm). Thirty-eight sections were obtained from the specimens, and contact radiography was performed. In the corresponding sections, structural parameters analogous to bone histomorphometry were determined. RESULTS: Significant correlations between MRI-derived structural parameters and those derived from macro pathological sections were found: r values of up to 0.75 were obtained (P < 0.01). The highest correlations were found for apparent bone volume/total volume and trabecular thickness. Image thresholding techniques showed a significant impact on these correlations (P < 0.01). The thinner MR sections were less susceptible to the different thresholding algorithms. CONCLUSIONS: Trabecular bone structure depicted by HR-MR images is significantly correlated with that shown in macro sections (P < 0.01); however, a number of limitations have to be considered, including the substantial impact of thresholding techniques and slice thickness.

Aged↗
PubMed2001

Inner ear fluid volumes and the resolving power of magnetic resonance imaging: can it differentiate endolymphatic structures?

Magnetic resonance imaging (MRI) can accurately recognize minute volumes as small as 1 mm3. The volumes of the utricle and saccule of the inner ear are within the resolving power of MRI, but these structures cannot be recognized because the endolymph and perilymph signals are identical. To clarify the interpretation and description of inner ear structures on MRI, we measured and calculated the volumes of the perilymphatic and endolymphatic spaces of the human ear. We found the total volume of the bony labyrinth to be approximately 192.5 mm3 (endolymph, 34.0 mm3; perilymph, 158.5 mm3).

Ear, Inner↗