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At least 343 records · Page 19Linked to original sources
PubMed1999

Functional brain imaging in neuropsychiatric disorders of childhood.

This review article presents a summary of the current state-of-the-art of functional brain imaging, with a primary focus on childhood neuropsychiatric disorders. Coverage is emphasized for developments that appear to be of current or potential future importance for the child neurologist and related pediatric specialist, and also from the perspective of the developmental neuroscientist. Emphasis is placed on the modalities of single photon emission computed tomography (SPECT), positron emission tomography (PET), and both "conventional" and "functional" magnetic resonance imaging, (MRI) including reference to the major new radiopharmaceutical and magnetic resonance-based imaging agents and techniques. The fundamental physicochemical processes underlying such studies are outlined, with citation of sources of more detailed information for the interested reader. A variety of imaging studies are reviewed for selected groups of childhood neuropsychiatric disorders, designed to illustrate the achievements and future promise of these imaging modalities. Areas of concentration are suggested for future imaging research in the field of childhood behavioral disorders, where these methods seem critical to improved understanding of pathogenetic mechanisms, as well as development of more effective treatment strategies.

Adolescent↗
PubMed1990

Receptor binding characterization of the benzodiazepine radioligand 125I-Ro16-0154: potential probe for SPECT brain imaging.

The binding of an iodinated benzodiazepine (BZ) radioligand has been characterized, particularly in regard to its potential use as a neuroreceptor brain imaging agent with SPECT (Single Photon Emission Computed Tomography). Ro16-0154 is an iodine-containing BZ antagonist and a close analog of Ro15-1788. In tissue homogenates prepared from human and monkey brain, the binding of 125I-labeled Ro16-0154 was saturable, of high affinity (Kd = 0.5 nM at 37 degrees C), and had high ratios of specific to non-specific binding (approximately 40:1). Physiological concentrations of NaCl (150 mM) enhanced specific binding approximately 15% compared to buffer without this salt. Kinetic studies of association and dissociation demonstrated a temperature dependent decrease in affinity with increasing temperature. Drug displacement studies confirmed that 125I-Ro16-0154 binds to the "central" type BZ receptor: binding is virtually identical to that of 3H-Ro15-1788 except that 125I-Ro16-0154 shows an almost 10 fold higher affinity at 37 degrees C. These in vitro results suggest that 123I-labeled Ro16-0154 shows promise as a selective, high affinity SPECT probe of the brain's BZ receptor.

Animals↗
PubMed1995

[Corticobasal degeneration: symptomatological, brain-imaging and electrophysiological studies].

Eight cases of clinically diagnosed corticobasal degeneration (CBD) were studied with reference to their symptomatology, brain-imagings and electrophysiological findings. The diagnosis was based on the combination of limb-kinetic apraxia (cortical sign), akinetic-rigid sign (extrapyramidal) and their unilateral predominance. Magnetic resonance imaging (MRI) and 123I-IMP or 99mTc-HMPAO SPECT findings were used to reinforce the diagnosis. The age at onset of 8 cases (4 males, 4 females) was 61 to 80 years (mean 66). Other common symptoms on admission consisted of dysequilibrium (8 cases), dysarthria (8), grasp reflex (6), supranuclear gaze palsy (6), tremor (6), limb dystonia (6) and alien limbs (5). MRI revealed parietal (3 cases) or frontoparietal (3) atrophy. SPECT showed decrease in cerebral blood flow in frontoparietal (3 cases) or frontoparietotemporal lobes (5). SPECT surpassed MRI to detect unilateral predominance of the lesions. With magnetic stimulation of the head and neck central motor conduction time (CMCT) was normal, while motor inhibitory periods (IPs) were significantly shorter in CBD patients compared with those in normal controls and the patients with Parkinson's disease. In 3 patients with reflex myoclonus, giant SEPs were not evoked, though with positive C-reflex, suggesting an elevated excitability of cerebral cortex unrelated to the production of giant SEPs.

Basal Ganglia↗
PubMed2004

Optimisation of the 3D MDEFT sequence for anatomical brain imaging: technical implications at 1.5 and 3 T.

An algorithm for the optimisation of 3D Modified Driven Equilibrium Fourier Transform (MDEFT) sequences for T1-weighted anatomical brain imaging is presented. Imaging parameters are optimised for a clinical whole body scanner and a clinical head scanner operating at 1.5 and 3 T, respectively. In vivo studies show that the resulting sequences allow for the whole brain acquisition of anatomical scans with an isotropic resolution of 1 mm and high contrast-to-noise ratio (CNR) in an acceptable scan time of 12 min. Typical problems related to the scanner-specific hardware configurations are discussed in detail, especially the occurrence of flow artefacts in images acquired with head transmit coils and the enhancement of scalp intensities in images acquired with phased array receive coils. It is shown both theoretically and experimentally that these problems can be avoided by using spin tagging and fat saturation.

Adult↗
PubMed2002

RF inhomogeneity compensation in structural brain imaging.

Three-dimensional T(1)-weighted magnetization-prepared rapid gradient-echo (MP-RAGE) sequences with centric phase encoding (PE) in the inner loop provide structural brain images with a high spatial resolution and high tissue contrast. A disadvantage of this sequence type is the susceptibility to inhomogeneities of the radiofrequency (RF) coil, which may result in poor image contrast in some peripheral regions. A special excitation pulse is presented which compensates for these effects in both the head/foot and anterior/posterior directions. This pulse has a duration of only 1.3 ms and is thus compatible with the short repetition times (TRs) required for MP-RAGE imaging. It is shown experimentally that images acquired with the compensation pulse may be segmented without using intensity correction algorithms during data postprocessing.

Artifacts↗
PubMed1978

Radionuclide brain imaging--its role and relation to CT scanning.

Separate CNS disease entities are discussed with either the complementary or exclusive indications for radionuclide brain imaging and computerized cranial tomography. Either modality alone has a potential overall precision somewhat in excess of 90% in the localization of cerebral lesions with the effectiveness of each modality differing according to the histology and anatomic location of the lesion. Most investigators agree that the combined application of the two procedures is far superior to their separate use. Routine dynamic isotope studies are essential and in addition, new radiopharmaceuticals and technological advances may improve the radionuclide evaluation of CNS disease. Areas discussed include: primary and secondary CNS neoplasms; acute cerebrovascular accidents; arteriovenous malformations; traumatic cerebrovascular disease; hydrocephalus and dementia; and intracranial inflammatory processes.

Adult↗
PubMed1994

Geriatric depression: brain imaging correlates and pharmacologic considerations.

The clinical approach to geriatric major depression involves a variety of special etiopathophysiologic, pharmacokinetic, and pharmacodynamic considerations. In regard to pathophysiology, modern brain imaging and postmortem assessments are elucidating neuropathologic changes in elderly depressives that challenge the notion that geriatric depression is simply a functional brain disorder. These data suggest (but do not yet establish) that many patients who experience depression onset at a late age may acquire affective disease on an arteriosclerotic basis. In contrast, elderly depressives who experience depression onset at an early age are more likely to have acquired depression due to genetic factors but may nevertheless develop degenerative neuropathologic changes over time. The presence of these neuropathologic changes appears to increase elderly patients' risk for developing the adverse central nervous system (CNS) effects of antidepressant treatments. They thereby add another level of complexity to the management of an age group in which pharmacokinetic and pharmacodynamic changes already contribute to the likelihood of adverse drug reactions. Fortunately, the last decade of antidepressant drug development has produced several new agents (including the serotonin selective reuptake inhibitors and more recently, venlafaxine and nefazodone) with substantially reduced CNS and cardiovascular toxicity that facilitate effective treatment of geriatric depression.

Age Factors↗
PubMedDate not supplied

The relationship between structural brain imaging and histopathologic findings in schizophrenia research.

The suggestion that schizophrenia may involve a neurodegenerative process has emanated from the highly replicated finding of ventricular enlargement in brain images of patients with this disorder. These investigations have provided a direct impetus for recent histopathologic studies seeking evidence of a neurodegenerative process in the brains of subjects with schizophrenia. Whereas most postmortem studies have reported the presence of atrophy and/or neuronal loss in several corticolimbic regions of subjects with schizophrenia, no quantitative study, to date, has detected an increase in the number of glial cells. For this reason the changes observed in postmortem schizophrenic brain are not consistent with a typical adult pattern of neuronal degeneration, such as that seen in Huntington's disease. Because several studies have reported various changes in layer II of the anterior cingulate, prefrontal, and entorhinal cortices, the histopathologic findings described are compatible with the idea that schizophrenia involves a disturbance of the "inside-out" migration or differentiation of cortical neurons that normally occurs during ontogenesis. A neurodevelopmental perturbation early in life could result in discrete alterations of corticolimbic circuitry that eventually contribute to the appearance of schizophrenic symptoms during adolescence and adulthood.

Adult↗
PubMed2006

Functional brain imaging in combined motor and sleep disorders.

The pathophysiology of sleep-related motor diseases and sleep dysfunction in movement disorders is widely unknown as yet. Functional brain imaging, in particular radioisotope and magnetic resonance techniques, are powerful tools to investigate possible pathomechanisms of combined sleep and motor dysregulation. In patients with Restless legs syndrome (RLS), only a subtle striatal dopamine deficit was found in PET and SPECT despite a good treatment effect of dopaminergic drugs. Functional MRI suggested a central generator of periodic limb movements during sleep (PLMs) in RLS. In contrast, a marked striatal dopamine depletion was demonstrated in patients with REM sleep behaviour disorder (RBD) as the base for the clinical and nosological overlap of RBD with parkinsonian disorders. PET and SPECT also suggested that sleep abnormalities in Parkinson's disease (PD), such as REM sleep diminution or increased PLMs, are indirect manifestations of the primary striatal dopamine deficiency.

Brain↗
PubMed2006

Cognitive and magnetic resonance imaging brain morphometric correlates of brain-derived neurotrophic factor Val66Met gene polymorphism in patients with schizophrenia and healthy volunteers.

CONTEXT: Relatively little is known about genetic determinants of cognitive dysfunction in schizophrenia. Recent studies suggest that a brain-derived neurotrophic factor (BDNF) prodomain single nucleotide polymorphism resulting in a valine (Val)-to-methionine (Met) substitution is associated with impaired declarative memory in healthy volunteers and patients with schizophrenia. These studies indicate that the BDNF(Met) variant may mediate hippocampal cognitive functions by modulating intracellular trafficking and activity-dependent BDNF release. To our knowledge, the way in which this functional single nucleotide polymorphism affects other neurocognitive measures has not been examined. Its role in determining cognitive deficits in schizophrenia has also not been systematically studied. OBJECTIVES: To characterize the neurocognitive and brain morphometric phenotypic correlates of the BDNF Val66Met polymorphism and to test the specificity of the BDNF(Met) variant on cognitive dysfunction in schizophrenia. DESIGN, SETTING, AND PARTICIPANTS: A comprehensive battery of standardized neuropsychological tests was administered to 144 healthy volunteers and 293 patients with schizophrenia spectrum disorder at a tertiary care university hospital. Approximately two thirds of the sample also underwent high-resolution magnetic resonance imaging brain scans. MAIN OUTCOME MEASURES: Genotype effects (in Met allele carriers vs Val homozygotes) on 5 cognitive domain z scores and magnetic resonance imaging gray matter brain volume measures (Talairach atlas-based cerebral lobes and optimized voxel-based morphometry) were examined using general linear models. RESULTS: On verbal memory, there was a significant genotype effect but no genotype x diagnosis effects. In both patients with schizophrenia and healthy volunteers, Met allele carriers had poorer verbal memory performance than their Val-homozygous counterparts. On visuospatial abilities, there were significant genotype and genotype x diagnosis effects. Met allele-associated visuospatial impairment was specific to patients with schizophrenia but not healthy volunteers. There were significant genotype effects on gray matter volumes within brain regions known to subserve these 2 cognitive domains, with Met allele carriers having smaller temporal and occipital lobar gray matter volumes. Optimized voxel-based morphometry further suggests that parietal heteromodal cortical gray matter deficits may underlie visuospatial impairment in patients with schizophrenia carrying the Met allele. CONCLUSIONS: We replicated the association between the BDNF(Met) variant and poor medial temporal lobe-related memory performance. The consonance of our cognitive and brain morphology findings further suggests that the BDNF(Met) variant may have a specific role in conferring visuospatial dysfunction in schizophrenia.

Adult↗
PubMed1995

Neurometrics, dynamic brain imaging and attention deficit hyperactivity disorder.

OBJECTIVE: The literature on the development of frequency analysis of the electroencephalogram (neurometrics) and functional dynamic brain imaging techniques is reviewed. Clinical applications in the diagnosis and treatment of learning disorders of childhood are discussed. CONCLUSIONS: While questions remain about the sensitivity and specificity of the neurometric method in diagnosing attention deficit hyperactivity disorder (ADHD), if the technique proved predictive of medication response, its importance would be established. However, evoked-potential studies, cerebral blood flow and cerebral glucose metabolic studies promise a better understanding of underlying psychological processes in ADHD.

Attention Deficit Disorder with Hyperactivity↗
PubMed2004

Server-based approach to web visualization of integrated three-dimensional brain imaging data.

The authors describe a client-server approach to three-dimensional (3-D) visualization of neuroimaging data, which enables researchers to visualize, manipulate, and analyze large brain imaging datasets over the Internet. All computationally intensive tasks are done by a graphics server that loads and processes image volumes and 3-D models, renders 3-D scenes, and sends the renderings back to the client. The authors discuss the system architecture and implementation and give several examples of client applications that allow visualization and analysis of integrated language map data from single and multiple patients.

Anatomy, Cross-Sectional↗
PubMed1999

Analysis of dynamic brain imaging data.

Modern imaging techniques for probing brain function, including functional magnetic resonance imaging, intrinsic and extrinsic contrast optical imaging, and magnetoencephalography, generate large data sets with complex content. In this paper we develop appropriate techniques for analysis and visualization of such imaging data to separate the signal from the noise and characterize the signal. The techniques developed fall into the general category of multivariate time series analysis, and in particular we extensively use the multitaper framework of spectral analysis. We develop specific protocols for the analysis of fMRI, optical imaging, and MEG data, and illustrate the techniques by applications to real data sets generated by these imaging modalities. In general, the analysis protocols involve two distinct stages: "noise" characterization and suppression, and "signal" characterization and visualization. An important general conclusion of our study is the utility of a frequency-based representation, with short, moving analysis windows to account for nonstationarity in the data. Of particular note are 1) the development of a decomposition technique (space-frequency singular value decomposition) that is shown to be a useful means of characterizing the image data, and 2) the development of an algorithm, based on multitaper methods, for the removal of approximately periodic physiological artifacts arising from cardiac and respiratory sources.

Brain↗
PubMed1999

Sources of mathematical thinking: behavioral and brain-imaging evidence.

Does the human capacity for mathematical intuition depend on linguistic competence or on visuo-spatial representations? A series of behavioral and brain-imaging experiments provides evidence for both sources. Exact arithmetic is acquired in a language-specific format, transfers poorly to a different language or to novel facts, and recruits networks involved in word-association processes. In contrast, approximate arithmetic shows language independence, relies on a sense of numerical magnitudes, and recruits bilateral areas of the parietal lobes involved in visuo-spatial processing. Mathematical intuition may emerge from the interplay of these brain systems.

Adult↗
PubMed2006

A non-parametric approach for co-analysis of multi-modal brain imaging data: application to Alzheimer's disease.

We developed a new flexible approach for a co-analysis of multi-modal brain imaging data using a non-parametric framework. In this approach, results from separate analyses on different modalities are combined using a combining function and assessed with a permutation test. This approach identifies several cross-modality relationships, such as concordance and dissociation, without explicitly modeling the correlation between modalities. We applied our approach to structural and perfusion MRI data from an Alzheimer's disease (AD) study. Our approach identified areas of concordance, where both gray matter (GM) density and perfusion decreased together, and areas of dissociation, where GM density and perfusion did not decrease together. In conclusion, these results demonstrate the utility of this new non-parametric method to quantitatively assess the relationships between multiple modalities.

Aged↗
PubMedDate not supplied

Accurate registration of serial 3D MR brain images and its application to visualizing change in neurodegenerative disorders.

PURPOSE: To propose and assess methods that permit the accurate and robust registration of serially acquired 3D MR scans and to demonstrate their application in neurodegenerative disorders. METHOD: 3D T1-weighted brain images were obtained on two or more occasions from 10 normal subjects and 8 patients with neurodegenerative disorders (scan intervals 3-21 months). Variants of an automated registration procedure were compared according to the goodness and robustness of match in normal subjects. Consistency was measured using scan triplets. Change was visualized by "difference overlay images." RESULTS: A multiresolution method was necessary for robust registration. Significant improvements in the registering of control scans were produced with voxel size correction (p < 0.05), matching only brain voxels (p < 0.05), and sinc interpolation (p < 0.05). Fast sinc resampling was 20 times faster than an equivalent previous method. Subvoxel accuracy was demonstrated. Difference overlay images showed little cerebral change in normal subjects; in Alzheimer disease patients, characteristic patterns of brain atrophy were observed even with scan intervals as short as 3 months. CONCLUSION: This methodology permits subvoxel comparison of routinely acquired serial 3D MR brain scans. It is a sensitive method for tracking patterns and rates of neuroanatomical change.

Adult↗