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PubMed2003

Three-dimensional maximum probability atlas of the human brain, with particular reference to the temporal lobe.

Probabilistic atlases of neuroanatomy are more representative of population anatomy than single brain atlases. They allow anatomical labeling of the results of group studies in stereotaxic space, automated anatomical labeling of individual brain imaging datasets, and the statistical assessment of normal ranges for structure volumes and extents. No such manually constructed atlas is currently available for the frequently studied group of young adults. We studied 20 normal subjects (10 women, median age 31 years) with high-resolution magnetic resonance imaging (MRI) scanning. Images were nonuniformity corrected and reoriented along both the anterior-posterior commissure (AC-PC) line horizontally and the midsagittal plane sagittally. Building on our previous work, we have expanded and refined existing algorithms for the subdivision of MRI datasets into anatomical structures. The resulting algorithm is presented in the Appendix. Forty-nine structures were interactively defined as three-dimensional volumes-of-interest (VOIs). The resulting 20 individual atlases were spatially transformed (normalized) into standard stereotaxic space, using SPM99 software and the MNI/ICBM 152 template. We evaluated volume data for all structures both in native space and after spatial normalization, and used the normalized superimposed atlases to create a maximum probability map in stereotaxic space, which retains quantitative information regarding inter-subject variability. Its potential applications range from the automatic labeling of new scans to the detection of anatomical abnormalities in patients. Further data can be extracted from the atlas for the detailed analysis of individual structures.

Adult↗
PubMed2000

Congenital cholesteatoma and cholesterol granuloma of the temporal bone: role of magnetic resonance imaging.

Magnetic resonance imaging (MRI) can be of significant benefit in characterizing expansile lesions of the petrous apex. MRI can be of particular help in distinguishing congenital cholesteatoma from cholesterol granuloma. Furthermore, with the advent of faster high-resolution scanning techniques, MRI can define precise spatial relationships of these masses with the middle and inner ear structures, internal carotid artery, jugular vein, and other structures of the skull base. MRI scanning is sensitive in detecting intracranial extension of these masses. MR angiography can provide additional information regarding the relationship of these masses with adjacent vascular structures and confirm patency of the adjacent vessels. In the postoperative period, MR scanning can help evaluate for complete removal, complication, recurrence, or formation of complicating granulation tissue.

Bone Diseases↗
PubMed2003

Structural brain abnormalities among relatives of patients with schizophrenia: implications for linkage studies.

Several studies suggest that the nonschizophrenic relatives of schizophrenic patients exhibit structural brain abnormalities that may be manifestations of genes that predispose to schizophrenia. In this work, we examine the utility of such measures for linkage analyses. Subjects were 45 nonpsychotic first-degree adult relatives of schizophrenic patients and 48 normal controls. Sixty contiguous 3-mm coronal, T1-weighted 3D magnetic resonance images of the entire brain were acquired on a 1.5-T magnet. We used factor analysis to derive MRI-based phenotypes for analysis. The factor analyses produced three factors that significantly discriminated relatives from controls. We used a linear combination of the three factor scores to derive an MRI phenotype. A receiver operating characteristic (ROC) analysis of this phenotype estimated an area under the curve (AUC) statistic of 0.85. The phenotype also discriminated nonpsychotic relatives having two schizophrenic relatives from those having only one. The nonpsychotic relatives of schizophrenic patients show deviant values on MRI measures of brain structure and the distribution of these deviations among relatives and controls suggests that if these results can be replicated, an MRI-derived phenotype could be useful for genetic linkage and association analyses.

Adult↗
PubMed2003

[Orbital vasculonervous network and orbital surgical compartments by high field magnetic resonance].

PURPOSE: To elucidate the possibilities and indications of high-resolution magnetic resonance imaging (MRI) in the study of the orbit and its contents. METHODS: Orbital anatomy was studied in sliced specimens of fifteen fresh frozen cadavers and the results were compared with those obtained in thirty asymptomatic subjects who underwent a magnetic resonance with 1.5 Tesla equipment. The information obtained was used to interpret the findings in twenty-two patients with various orbital diseases. RESULTS: High-resolution MRI allows visualization of structures difficult to assess previously, like the cerebrospinal fluid (CSF) surrounding the optic nerve, the complete intraorbital route and the exit of the third cranial nerve, the ophthalmic artery and the intraorbital relationships of the sixth cranial nerve, which can be clearly differentiated from the lateral rectus muscle. CONCLUSIONS: High-resolution MRI is a very useful tool for the study of the orbit and its content. It provides accurate diagnoses through non-invasive procedures and facilitates the planning of the surgical approaches by improving the visualization of pathologic orbital structures. lcarlos@correo.uniovi.es

Cadaver↗
PubMed1987

Magnetic resonance imaging in temporal lobe epilepsy: pathological correlations.

A retrospective single-blind study assessing the value of magnetic resonance imaging (MRI) in 48 patients treated surgically for temporal lobe epilepsy was carried out. The imaging findings were correlated with the surgical findings in all cases. Abnormal MRI signals were detected in 34 of 48 (71%) epileptic patients and in 3 of 48 (6.2%) normal or disease control subjects. Twelve patients had structural foreign-tissue lesions, all detected by MRI. Of 14 patients with severe gliosis of the neocortex and/or mesial temporal structures, 11 had abnormal MRI scans. In patients with mild or moderate gliosis of mesial temporal structures, 6 of 12 had abnormal MRI scans. These results indicate that MRI is a sensitive technique for localizing foreign-tissue lesions, mesial temporal sclerosis, and gliosis in patients with intractable temporal lobe seizures.

Adolescent↗
PubMed2005

Perceived self-control of seizures in patients with uncontrolled partial epilepsy.

Many patients with epilepsy have warning symptoms prior to seizure onset, and some of these individuals report the ability to abort or prevent these seizures. We investigated the clinical characteristics of perceived self-control of seizures in 174 patients with uncontrolled partial epilepsy. The warning symptoms were categorized as premonitory (prodrome) and as initial symptoms of simple partial seizure onset, depending on the relationship between the warning events and the ensuing seizures. About 50% of the patients with simple partial seizure onset and about 70% of those with prodrome or premonitory symptoms reported that they could abort or prevent their seizures by various self-developed techniques. Patients who attempted to abort or prevent their seizures reported success rates as high as 80%. The proportion of patients with secondary generalized seizures was significantly lower in patients who tried to abort their seizures than in those who did not (p<0.05). The ability to prevent seizures was significantly higher in patients with brain lesions on MRI than in those without lesions (p<0.05). These results suggest that spontaneously developed methods are helpful in controlling seizures in some patients with uncontrolled partial epilepsy and that the potential success of self-control methods may be influenced by structural abnormalities on brain MRI.

Adolescent↗
PubMed1991

A comparison of CT and MRI in the assessment of the pituitary and parasellar region.

We have carried out a prospective study to compare high resolution thin slice, contrast-enhanced, axial computed tomography (CT) with unenhanced magnetic resonance imaging (MRI) at 1.5T in the assessment of the pituitary and parasellar region. Forty patients with suspected pituitary disease presenting to an endocrine unit were studied. MRI was superior to CT for the identification of the posterior pituitary and pituitary stalk and was better at showing the cystic nature of tumours. Visualization of the optic chiasm and assessment of displacement of the optic chiasm and the carotid arteries were also better with MRI. CT was equally good at showing cavernous sinus displacement or invasion, sphenoid sinus invasion and erosion of the floor of the sella turcica and was the only technique able to show calcification of the gland. More focal abnormalities were seen in the pituitary gland with CT than with unenhanced MRI, but there was a higher false positive rate for microadenoma detection with CT. All the scans were interpreted separately by three observers, two radiologists and one clinician. The percentage agreement between the observers for the identification of pituitary and parasellar structures was better for MRI than for CT and the clinician in particular found interpretation of the MR images easier. MRI thus not only gives more information overall than CT but it is a more reliable technique between different observers for the assessment of the pituitary and parasellar region.

Aged↗
PubMed2000

The joint effect of apolipoprotein E epsilon4 and MRI findings on lower-extremity function and decline in cognitive function.

BACKGROUND: Cognitive decline and poor physical function are risk factors for disability in old age and may occur more often in subjects with the apolipoprotein E epsilon4 (ApoE-epsilon4) allele. The objective of this study was to investigate the joint effect of ApoE-epsilon4 and structural changes detected on MRI brain scans on cognitive decline and lower-extremity function. METHODS: Brain MRI (1.5 T), neuropsychological tests, and lower-extremity physical function tests were administered to World War II male veteran twins ages 69 to 80. Quantification of MRI scans used a previously published algorithm to segment brain images into total cerebral brain (TCB), cerebrospinal fluid (CSF), and white-matter hyperintensity (WMH) volumes. A short battery of physical performance tests was used to assess lower-extremity function. Ten-year changes in performance on the Mini-Mental State Exam (MMSE), the Benton Visual Retention Test (BVRT), and the Digit Symbol Substitution (DSS) test were used to assess cognitive decline. RESULTS: For the sample as a whole, the comparison of subjects by median split of total cerebral brain volume found that those with brain volumes below the median performed worse on tests of gait and balance (p < .01) and experienced greater cognitive decline on the MMSE and BVRT cognitive test batteries (both p < .01). In addition, subjects with WMH volumes above the median had poor performance on the standing balance tasks and experienced greater decline on the DSS test (p < .01). Stratified analyses revealed that the joint effect of radiological findings and the ApoE-epsilon4 allele on cognitive decline and lower-extremity function was often greater than that expected from the separate effects combined. CONCLUSIONS: We conclude that radiological findings in conjunction with ApoE-epsilon4 may single out a group at higher risk for dementia. We speculate that the observed interaction effect may be due to increased susceptibility to brain injury or impaired repair mechanisms in subjects with ApoE-epsilon4.

Aged↗
PubMed1995

Some methodological issues in neuroradiological research in psychiatry.

An outline is given of some of the methodological issues discussed in neuroradiological research on psychiatric illness. Strengths and shortcomings of magnetic resonance imaging (MRI) in depicting and quantifying brain structures are described. Temporal lobe anatomy and pathology are easily accessible to MRI, whereas limits on anatomical delineation hamper approaches to frontal lobe study. White matter hyperintense lesions are sensitively depicted by MRI, but specificity is limited. Distinction of vascular and primary degenerative dementia is considerably improved by CT and MRI analysis. Computed tomography (CT) and MRI have enhanced the understanding of treatable organic psychiatric disorders, e.g., normal pressure hydrocephalus. Subcortical and white matter pathology has been replicated in CT and MRI studies of late-onset psychiatric disorders, clinical overlap with cerebrovascular disease or neurodegeneration may be of import. Transcranial sonography findings of brainstem structural change specific to unipolar depression may contribute to the understanding of affective psychoses. Magnetic resonance spectroscopy and functional MRI are likely to stimulate psychiatric research in the future.

Brain↗
PubMed1999

Effects of sedation, stimulation, and placebo on cerebral blood oxygenation: a magnetic resonance neuroimaging study of psychotropic drug action.

The effects of pharmacologic depression and stimulation of cerebral activity were investigated in seven healthy young volunteers using blood oxygenation-sensitive MRI at 2.0 T. Dynamic gradient-echo imaging (7 min) was performed before, during and after the intravenous application of 10 mg diazepam and 15 mg metamphetamine as well as of the corresponding drug placebos (isotonic saline) in a brain section covering frontotemporal gray matter, subcortical gray matter structures, and cerebellum. The MRI responses were significantly different for the two drugs applied (p = 0.01). Relative to signal strength during injection, metamphetamine elicited a signal increase of 0.97 +/- 0.03% (mean +/- SD, p = 0.02) within the whole section 4-5 min after injection. Similarly, both placebo conditions led to a small signal increase, i.e. 0.50 +/- 0. 03% (n.s.) for the metamphetamine placebo and 0.40 +/- 0.07% (p = 0. 03) for the diazepam placebo. Diazepam abolished this signal increase. A topographic analysis revealed the metamphetamine-induced signal increase to be more pronounced in subcortical gray matter structures (p = 0.01) and cerebellum (p = 0.02) than in frontotemporal cortical gray matter (p = 0.04). This finding is in agreement with the hypothesis that pertinent responses not only reflect global cerebral hemodynamic adjustments, but also localized perfusion changes coupled to alterations in synaptic activity. The occurrence of a placebo response is best explained by expectancy and may provide a confounding factor in the design of functional activation experiments.

Adult↗
PubMed2001

Brain structure, genetic liability, and psychotic symptoms in subjects at high risk of developing schizophrenia.

BACKGROUND: Structural magnetic resonance imaging (MRI) of the brain in patients with schizophrenia has consistently demonstrated several abnormalities. These are thought to be neurodevelopmental in origin, as they have also been described in first episode cases, although there may be a progressive component. It is not known at which point in development these abnormalities are evident, nor to what extent they are genetically or environmentally mediated. METHODS: One hundred forty-seven high-risk subjects (with at least two affected first or second degree relatives), 34 patients in their first episode, and 36 healthy control subjects received an MRI scan covering the whole brain. After inhomogeneity correction, regions of interest were traced by three group-blind raters with good inter-rater reliability. Regional brain volumes were related to measures of genetic liability to schizophrenia and to psychotic symptoms elicited at structured psychiatric interviews. RESULTS: High-risk subjects had statistically significantly reduced mean volumes of the left and right amygdalo-hippocampus and thalamus, as compared to healthy control subjects. They also had bilaterally larger amygdalo-hippocampi and bilaterally smaller lenticular nuclei than the schizophrenics. High-risk subjects with symptoms had smaller brains than those without. The volumes of the prefrontal lobes and the thalamus were the only consistent associates of genetic liability. CONCLUSIONS: Subjects at high risk of developing schizophrenia have abnormalities of brain structure similar to but not identical to those found in schizophrenia. Our results suggest that some structural abnormalities are genetic trait or vulnerability markers, others are environmentally mediated, and that the development of symptoms is associated with a third overlapping group of structural changes. Particular risk factors for schizophrenia may interact at discrete time points of neurodevelopment with different effects on specific brain regions and may represent relatively distinct disease processes.

Amygdala↗
PubMed2002

Neuroimaging and the progression of epilepsy.

Several lines of evidence can be used to try to answer the question of whether epilepsy is a progressive disease, and whether persistent seizures, or the underlying process itself, cause neuronal injury. The results of clinical studies have been inconclusive. Neuroimaging studies offer a quantitative approach. In patients with temporal lobe epilepsy, structural magnetic resonance imaging (MRI) has shown volume reductions ipsilateral to the epileptic focus in hippocampal and extrahippocampal regions; the former, in cross-sectional studies, increase with increasing epilepsy duration. Other factors associated with increasing hippocampal atrophy include a history of complex or prolonged febrile seizures, and generalized tonic-clonic seizure number. Positron emission tomography (PET) has shown supporting results. However, these studies have been cross-sectional rather than longitudinal. Preliminary results from prospective imaging studies using fluorodeoxyglucose PET and volumetric MRI show that patients with more recent seizure onset are less likely to have hypometabolism or volume loss than those with a long history of epilepsy. Alternate interpretations of these data include a possible progressive effect of epilepsy, or a tendency for patients with structural or functional findings at seizure onset to be more likely to develop uncontrolled epilepsy. In addition to the human studies that have been performed, parallel investigations in animal models using some of the same imaging techniques may help to unravel the factors associated with neuronal injury due to seizures, and aid in interpreting results of clinical studies.

Animals↗
PubMed1999

Neuroanatomy of comorbid schizophrenia and learning disability: a controlled study.

BACKGROUND: Reasons for the higher frequency of schizophrenia in learning-disabled populations are uncertain. We investigated the neuroanatomical basis for this phenomenon by structural magnetic resonance imaging (MRI) in patients with learning disability and schizophrenia, learning-disabled patients, and patients with schizophrenia. METHODS: Age-matched and sex-matched patients with learning disability (20 cases), schizophrenia (25), and both disorders (23) underwent MRI scans of the brain. Whole brain areas and specific regions of interest were examined. 29 normal controls were also scanned. FINDINGS: The scans of the group with both disorders were closely similar to those of the schizophrenic group, in terms of both general structures and the structure of the amygdala-hippocampus. However, the amygdala-hippocampus was significantly smaller on both sides than that of normal controls (left 4.1 vs 4.5 cm3, p=0.011; right 4.2 vs 4.99 cm3, p<0.0001). The brains of learning-disabled patients were generally smaller than those of the other three groups, but the amygdalohippocampal complexes were larger. INTERPRETATION: In terms of brain structure, patients with comorbid learning disability and schizophrenia resemble patients with schizophrenia and not those with learning disability. We suggest that the higher frequency of schizophrenia in learning-disabled patients is due to a greater tendency of schizophrenic patients to develop cognitive deficits, and that within the learning-disabled population there may be individuals whose deficits result from undiagnosed schizophrenia.

Adolescent↗
PubMed1996

In vitro delineation of human brain-stem anatomy using a small resonator: correlation with macroscopic and histological findings.

Our purpose was to investigate the potential of an experimental animal coil using a commercial MRI unit to delineate the anatomical structure of the human brain stem. Three formaldehyde-fixed brain-stem specimens were examined by MRI and sectioned perpendicular to their longitudinal axis. The images were compared with gross anatomy and myelin-stained histological sections. Fibre tracts and nuclei which were not evident on examination of the unstained specimen were readily identified by MRI. Due to its inherent grey/white matter contrast, MRI with a high-resolution coil delineates anatomical structures in a way comparable to the myelin-stained histological sections. However, pigmented structures, readily visible on examination of the unstained specimen were discernible on neither MRI nor on myelin-stained sections. The excellent anatomical detail and grey/white matter contrast provided by these images could make MRI a useful adjunct to the pathologist investigating brain disease.

Brain Stem↗
PubMed1993

Normal brain F-18 FDG-PET and MRI anatomy.

Image registration techniques will become increasingly important in correlative multimodality imaging. In the case of PET, a structural imaging study can be invaluable in correlating structure metabolism relationships. A registered brain atlas of PET and MRI has been developed by the authors that allows clinicians, residents, fellows, and others to refer to a structural abnormality on MRI or metabolic abnormality on PET and correlate it neuro-anatomically.

Brain↗
PubMed1990

Motor dysfunction in HIV-infected patients without clinically detectable central-nervous deficit.

Motor tests were performed in 50 HIV-infected patients in all stages according to the current CDC classification, but without any clinically evident central nervous system deficit, and the results compared with an age-matched control group. Patients were excluded from the study if there was alcohol or drug abuse, fever and/or opportunistic cerebral infection. The parameters tested were postural tremor of the outstretched hands, most rapid voluntary alternating index finger movements (MRAM) and rise time of most rapid index finger extensions (MRC). Whereas tremor peak frequencies did not differ significantly in the patients and controls, MRAM and rise times of MRCs showed significant slowing in the patient group. Morphologically, the motor test performance of the HIV-infected patients was similar to that of patients with manifest basal ganglia disease (Parkinson's, Huntington's and Wilson's diseases). MRI scans of all patients were normal. It is concluded that in HIV-infected patients there is a very early subclinical central nervous system affection, especially of the basal ganglia, which is detectable with appropriate, quantitative motor function tests. These functional abnormalities precede the structural alterations in the MRI scans.

Adult↗
PubMed2000

Inflammatory abdominal aortic aneurysms: diagnosis with gadolinium enhanced T1-weighted imaging.

AIM: Inflammatory abdominal aortic aneurysms (IAAA) are a variant of abdominal aortic aneurysms, which are associated with an increased morbidity. The diagnosis of IAAA has traditionally been established with a combination of clinical and laboratory findings together with contrast enhanced CT. There is a high incidence of renal impairment in this group, and therefore contrast enhanced CT may be harmful. PATIENTS AND METHODS: Five patients with IAAA underwent T1-weighted spin echo and gradient echo gadolinium enhanced abdominal MRI. A total of eight examinations were performed, including three patients who underwent repeat MRI following steroid therapy. RESULTS: The inflammatory cuff was clearly identified following gadolinium administration in all eight examinations. The cuff enhanced homogeneously in all patients with no alteration in appearance following steroid therapy. The intravenous administration of gadolinium DTPA enabled clearer definition of locally involved structures. CONCLUSION: Gadolinium enhanced MRI readily demonstrates features of IAAA. In view of potential renal impairment in this patient group, we recommend this technique in preference to contrast enhanced CT in the initial investigation of inflammatory abdominal aortic aneurysms.

Aged↗
PubMed1997

In vitro magnetic resonance microimaging of experimental osteoarthritis in the rat knee joint.

OBJECTIVE: To visualize articular changes during iodoacetate induced osteoarthritis (OA) of the rat knee using high resolution magnetic resonance imaging (MRI). METHODS: All images were acquired on a 8.5T microimager on ex vivo rat knees. After optimization studies, 3D spin echo sequences were used with TR 1200 ms and TE 15 ms; 40 sagittal images were obtained with a resolution of 400 x 60 x 60 microns. OA lesions were achieved by injecting 3 mg iodoacetate in the right knee joint (Day 0). Progression of OA changes was studied at Days 5, 10, 15, 20, 30, 90 and corresponding radiographs and histological sections were obtained. RESULTS: Spin echo images of the normal rat knee clearly visualized cortical bone, calcified menisci, patella, and cruciate ligaments as dark regions. Cartilage and muscles appeared as intermediate signal. In some cases a trilaminar appearance of cartilage and growth plate was depicted. This appearance persisted at Day 5, although cartilage presented a marked loss of proteoglycans. After Day 10 the menisci appeared irregular and inhomogeneous. After Day 15, MRI showed important alterations of articular cartilage, predominant on weight bearing areas of femoral condyles. Osteophytic remodeling was also seen around the patella. From Day 20 to Day 90 anatomical changes progressively affected epiphyseal bone, leading to subchondral cysts and loss of its regular trabecular structure. CONCLUSION: High field MRI provides a sensitive method for investigating ex vivo focal erosions of cartilage and established osteochondral remodeling in experimental OA in the rat. In this model, microimaging provides more information about early modifications of cartilage and soft tissue than radiographic exploration, in good correlation with histological data.

Animals↗