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At least 145 records · Page 8Linked to original sources
PubMed2005

New fields of research in posttraumatic stress disorder: brain imaging.

PURPOSE OF REVIEW: This paper reviews the most recent literature on brain imaging research in posttraumatic stress disorder. Neuroimagery identifies several cerebral modifications occurring after a significant psychological trauma, and it contributes to a better understanding of the pathophysiology of posttraumatic stress disorder. A systematic search of the literature in English, French, German and Dutch from January 2003 to August 2004 was performed on MEDLINE. References cited in all trials were searched iteratively to identify missing studies. RECENT FINDINGS: There appears to be a consensus in brain imaging findings concerning posttraumatic stress disorder: a diminished volume of the hippocampus uni- or bilateral (on the structural level) and a hyper-reactivity in the amygdala, with a lowered activation in the anterior cingular cortex (at the functional level). These findings are in agreement with several neurological and psychological studies suggesting that hyper-reactivity in the amygdala corresponds to a constellation of symptoms of anxiety in posttraumatic stress disorder, while the lowered activation of the prefrontal and the anterior cingular cortex could reflect slower extinction of a conditioned emotional response. SUMMARY: These neuroimaging findings could contribute to a better understanding of posttraumatic stress disorder. The integration of neurobiological, social and psychological findings may lead to an improved approach to the pathophysiology of posttraumatic stress disorder and perhaps to the development of new pharmacological treatment. Future studies could integrate the disparate findings among numerous biological systems and propose an integrative structural, functional and endocrinological model.

Journal Article↗
PubMedDate not supplied

Mapping between MR brain images and a voxel model.

This paper describes an approach to establish the correspondence between a magnetic resonance (MR) image of the brain and a slice through a 3D anatomical model. The model is of voxel structure that symbolically labels primary tissue types such as grey matter, white matter, CSF, etc. In this approach a slice is first searched for in the model to achieve the best general match with the brain MR image in question. The operation involves a minimization of parameters such as position, rotation, slant, tilt and enlargement. Having thus found a globally good registration between the image and the model, local matches that link every pixel in the image through to the model slice are then searched for. This pixel-by-pixel match is expressed within a pair of maps, one for the vertical deformation and the other for the horizontal one. The matching algorithm consists of a series of octave separated blurring convolutions combined with exhaustive grey-valued correlation. Because every pixel in the model slice is labelled in terms of its tissue type, and because every pixel in the image has been matched directly to the model, every pixel in the image is now classified. This classification is used directly to perform segmentation which serves as a basis for the computation of medically relevant indices.

Algorithms↗
PubMed2004

Combining brain imaging with microarray: isolating molecules underlying the physiologic disorders of the brain.

Many diseases of the nervous system cause dysfunction by impairing neuronal physiology more than by altering brain anatomy--including age-related cognitive decline, most psychiatric disorders, and even the earliest stages of Alzheimer's disease. The absence of clear anatomical markers makes it difficult to identify targeted cells, which in turn impedes attempts to isolate the pathogenic molecules that cause physiologic disruption. Here we show how brain imaging and microarray can be used as complimentary techniques that together can characterize the cellular and molecular aspects of this class of diseases.

Adult↗
PubMed1999

Brain imaging studies of cocaine abuse: implications for medication development.

Contemporary in vivo brain imaging techniques confer the ability to assess brain function and structure noninvasively, and thereby can yield information to help guide the development of new treatments for substance abuse. The advantages and limitations of the major imaging modalities (positron emission tomography [PET], single photon emission computed tomography [SPECT], structural and functional magnetic resonance imaging [MRI, fMRI, respectively]) are discussed with respect to their applicability to research on cocaine abuse. The effects of acute administration of cocaine have been studied using PET and fMRI, with PET manifesting decreases in cerebral glucose metabolism and blood flow, and fMRI revealing regional effects that are correlated temporally with subjective responses. In addition, studies of drug abusers, abstinent from cocaine for various lengths of time, have revealed persistent differences in brain function and structure, especially in the frontal cortex, when compared with parameters in the brains of subjects who do not use illicit drugs of abuse. PET studies also have revealed abnormalities in markers for dopaminergic and opioid systems during withdrawal from cocaine. Moreover, studies of cue-elicited craving for cocaine demonstrate a connection between the response to drug-related stimuli and neural elements of cognition and emotion. The future directions of in vivo brain imaging to identify functional and structural alterations in the brains of cocaine abusers are discussed in relation to the development of medications to treat cocaine dependence.

Animals↗
PubMed1991

Structural and functional brain imaging in schizophrenia.

We present an evaluation of the contribution of structural and functional brain imaging to our understanding of schizophrenia. Methodological influences on the validity of the data generated by these new technologies include problems with measurement and clinical and anatomic heterogeneity. These considerations greatly affect the interpretation of the data generated by these technologies. Work in these fields to date, however, has produced strong evidence which suggests that schizophrenia is a disease which involves abnormalities in the structure and function of many brain areas. Structural brain imaging studies of schizophrenia using computed tomography (CT) and magnetic resonance imaging (MRI) are reviewed and their contribution to current theories of the pathogenesis of schizophrenia are discussed. Positron emission tomography (PET) studies of brain metabolic activity and dopamine receptor binding in schizophrenia are summarized and the critical questions raised by these studies are outlined. Future studies in these fields have the potential to yield critical insights into the pathophysiology of schizophrenia; new directions for studies of schizophrenia using these technologies are identified.

Brain↗
PubMed1999

Normal myelination of the pediatric brain imaged with fluid-attenuated inversion-recovery (FLAIR) MR imaging.

BACKGROUND AND PURPOSE: As in adult imaging, FLAIR can be applied to pediatric brain imaging, and this requires an appreciation of the normal pediatric brain appearance by FLAIR imaging. The purpose of this study was to describe the MR appearance of the brain in normal infants and young children as demonstrated by fluid-attenuated inversion-recovery (FLAIR) MR imaging. METHODS: We retrospectively examined MR brain studies, interpreted as normal by pediatric radiologists, from 29 patients (aged 1 to 42 months) to catalog the appearance of myelination in multiple brain areas. RESULTS: On T2-weighted images, white matter progressed from hyperintense to hypointense relative to adjacent gray matter over the first 2 years of life. An analogous, although slightly delayed sequence was observed on FLAIR images with the exception of the deep cerebral hemispheric white matter, which followed a triphasic sequence of development. On FLAIR images, the deep cerebral white matter was heterogeneously hypointense relative to gray matter in the young infant, became hyperintense early in the first few months of life, and then reverted to hypointense during the second year of life. CONCLUSION: The normal appearance and development of brain white matter must be taken into account when interpreting FLAIR images of infants and young children.

Adult↗
PubMed2002

Improved optimization for the robust and accurate linear registration and motion correction of brain images.

Linear registration and motion correction are important components of structural and functional brain image analysis. Most modern methods optimize some intensity-based cost function to determine the best registration. To date, little attention has been focused on the optimization method itself, even though the success of most registration methods hinges on the quality of this optimization. This paper examines the optimization process in detail and demonstrates that the commonly used multiresolution local optimization methods can, and do, get trapped in local minima. To address this problem, two approaches are taken: (1) to apodize the cost function and (2) to employ a novel hybrid global-local optimization method. This new optimization method is specifically designed for registering whole brain images. It substantially reduces the likelihood of producing misregistrations due to being trapped by local minima. The increased robustness of the method, compared to other commonly used methods, is demonstrated by a consistency test. In addition, the accuracy of the registration is demonstrated by a series of experiments with motion correction. These motion correction experiments also investigate how the results are affected by different cost functions and interpolation methods.

Acoustic Stimulation↗
PubMed1998

Chemical and physiologic brain imaging in schizophrenia.

Technologic advances in functional brain imaging have provided exciting and informative insights into the functional neuroanatomy and neurochemistry of schizophrenia. Using MR spectroscopy, it has been possible to examine in vivo brain metabolism and to relate observed changes to physiological processes occurring at a cellular level. Positron emission tomography and single photon emission computed tomography have revealed disturbances of cerebral blood flow and glucose metabolism in patients with schizophrenia. More recently, these tools have also proved most useful in studying the relative receptor occupancy of typical and atypical antipsychotic medications.

Antipsychotic Agents↗
PubMed2006

Brain imaging tools in neurosciences.

In this chapter brain imaging tools in neurosciences are presented. These include a brief overview on single-photon emission tomography (SPET) and a detailed focus on positron emission tomography (PET) and functional magnetic resonance imaging (fMRI). In addition, a critical discussion on the advantages and disadvantages of the three diagnostic systems is added. Furthermore, this article describes the image analysis tools from visual analysis over region-of-interest technique up to statistical parametric mapping, co-registration methods, and network analysis. It also compares the newly developed combined PET/CT scanner approach with established image fusion software approaches. There is rapid change: Better scanner qualities, new software packages and scanner concepts are on the road paved for an amply bright future in neurosciences.

Animals↗
PubMed1999

Is the spatial distribution of brain lesions associated with closed-head injury predictive of subsequent development of attention-deficit/hyperactivity disorder? Analysis with brain-image database.

PURPOSE: To determine whether there is an association between the spatial distribution of lesions detected at magnetic resonance (MR) imaging of the brain in children after closed-head injury and the development of secondary attention-deficit/hyperactivity disorder (ADHD). MATERIALS AND METHODS: Data obtained from 76 children without prior history of ADHD were analyzed. MR images were obtained 3 months after closed-head injury. After manual delineation of lesions, images were registered to the Talairach coordinate system. For each subject, registered images and secondary ADHD status were integrated into a brain-image database, which contains depiction (visualization) and statistical analysis software. Using this database, we assessed visually the spatial distributions of lesions and performed statistical analysis of image and clinical variables. RESULTS: Of the 76 children, 15 developed secondary ADHD. Depiction of the data suggested that children who developed secondary ADHD had more lesions in the right putamen than children who did not develop secondary ADHD; this impression was confirmed statistically. After Bonferroni correction, we could not demonstrate significant differences between secondary ADHD status and lesion burdens for the right caudate nucleus or the right globus pallidus. CONCLUSION: Closed-head injury-induced lesions in the right putamen in children are associated with subsequent development of secondary ADHD. Depiction software is useful in guiding statistical analysis of image data.

Adolescent↗
PubMedDate not supplied

Elastically deforming 3D atlas to match anatomical brain images.

To evaluate our system for elastically deforming a three-dimensional atlas to match anatomical brain images, six deformed versions of an atlas were generated. The deformed atlases were created by elastically mapping an anatomical brain atlas onto different MR brain image volumes. The mapping matches the edges of the ventricles and the surface of the brain; the resultant deformations are propagated through the atlas volume, deforming the remainder of the structures in the process. The atlas was then elastically matched to its deformed versions. The accuracy of the resultant matches was evaluated by determining the correspondence of 32 cortical and subcortical structures. The system on average matched the centroid of a structure to within 1 mm of its true position and fit a structure to within 11% of its true volume. The overlap between the matched and true structures, defined by the ratio between the volume of their intersection and the volume of their union, averaged 66%. When the gray-white interface was included for matching, the mean overlap improved to 78%; each structure was matched to within 0.6 mm of its true position and fit to within 6% of its true volume. Preliminary studies were also made to determine the effect of the compliance of the atlas on the resultant match.

Anatomy, Artistic↗
PubMed1998

Morphological brain imaging studies on major psychoses.

The first application of computed tomographic scan to the schizophrenic brain by Johnstone et al. initiated a new neuroscience research era with new perspectives on the neurobiological aspects of major psychoses. The most common paradigm in the flurry of brain imaging studies following the first report was the case-control study comparing controls and patients with major psychoses. However, some application was also made of sophisticated case-control paradigms, such as comparisons between affected and non-affected identical twins discordant for schizophrenia. Very few prospective cohort studies have been applied in this field. During the past two decades of studies, several brain morphological features have converged. Both schizophrenics and patients with affective disorders showed subtle but significant quantitative differences in brain structures compared with controls. For schizophrenia, the differences were in the lateral and third ventricles, medial temporal lobe, supratemporal gyrus, frontal lobe and such subcortical nuclei as striatum and thalamus. For affective disorders, they were in the cortical sulci, lateral ventricle, striatum, pituitary and adrenal glands. Generally, the differences were greater in schizophrenics, in males and on the left side than in patients with affective disorders, in females and on the right side. Qualitative morphological abnormalities such as T2-weighted hyperintensity were also demonstrated in elderly patients with affective disorders. For both schizophrenia and affective disorders, abnormal anatomical neurocircuit models of the respective pathophysiologies have been proposed to explain the brain multi-lesions. Some recommendations for future research in the structural brain imaging of major psychoses have also been proposed.

Bipolar Disorder↗
PubMed1991

[Three-dimensional MR brain image using volume rendering method].

3-dimensional image reconstructed from the data of computer tomography has provided useful informations for the pre-operative evaluation in the field of neurosurgery and plastic surgery. However CT has failed to visualized the 3-dimensional surface image of the central nervous system. On the other hand the progress of high-speed data acquisition technique and 3-dimensional fourier transformation has enabled the practical 3-dimensional image using magnetic resonance imager. However for the visualization of a pure surface image of the brain and spinal cord a sophisticated method and special image work station has been necessary. The authors describe a technique for the pure surface image of the brain and spinal cord using a normal mini-computer system and magnetic resonance imager. This image has a good correlation to the macroscopic anatomical brain surface (sulci and gyri).

Brain↗
PubMed1997

Brain imaging of schizophrenia--the dopamine hypothesis.

The dopamine hypothesis of schizophrenia was formulated 30 years ago and postulates that the symptoms of schizophrenia are related to an increased central dopaminergic neurotransmission. The two fundamental assumptions that underlay the dopamine hypothesis of schizophrenia have received support from brain imaging studies on the dopamine system. There is a high occupancy of central D2-dopamine receptors in patients that are treated with clinically effective doses of classical antipsychotic drugs and recent studies indicate an abnormal function of the presynaptic dopaminergic neuron. Early reports of elevated postsynaptic D2-dopamine receptors in schizophrenic brains post mortem have, however, not been consistently confirmed by brain imaging studies of young neuroleptic-naïve patients with schizophrenia. Suitable methods are now being developed for brain imaging of the dopamine system in the limbic and neocortical regions that are of central interest in schizophrenia research.

Amphetamines↗
PubMed2002

Predictors of treatment response in bipolar disorders: evidence from clinical and brain imaging studies.

The clinical features of bipolar disorders can be correlated with responses to medications. Patients who respond to lithium, for example, often present differently from those who respond to divalproex or carbamazepine, but the correlations are relatively modest. Brain-imaging tools, such as positron emission tomography (PET), single photon emission computed tomography (SPECT), and functional magnetic resonance imaging (fMRI), can relate brain function to clinical features and medication responses. For example, in depression, it appears that prefrontal cortical function is decreased while subcortical anterior paralimbic activity is increased. Preliminary evidence suggests that baseline metabolism increases and decreases in the left insula may be associated with carbamazepine and nimodipine responses, respectively, and that cerebral lithium concentrations may correlate with antimanic effects. Although it is not yet a clinical tool for bipolar disorders, brain imaging provides useful research data to understand the fundamental neurobiology of mood disorders and to more effectively target therapeutics.

Anticonvulsants↗
PubMed2002

Acyl-protected hydroxylamines as spin label generators for EPR brain imaging.

In a search for novel electron paramagnetic resonance (EPR) brain imaging agents, we have designed and synthesized the acyl-protected hydroxylamines 1-acetoxy-4-methoxycarbonyl-2,2,6,6-tetramethylpiperidine (AMCPe), 1-acetoxy-3-methoxycarbonyl-2,2,5,5-tetramethylpyrrolidine (AMCPy), and 1-acetoxy-3-(acetoxymethoxy)carbonyl-2,2,5,5-tetramethylpyrrolidine (DACPy), in which both the ring size and the number of ester functions were varied. In all of them, the nitroxide was first reduced and the resultant hydroxylamine was then protected with an acetyl group. These compounds are lipophilic, which is a major prerequisite for blood-brain barrier penetration. Once in the brain, esterases and oxidants quickly convert these derivatives into ionic, water-soluble radicals and thus EPR detectable species that then reside in the central nervous system for periods of time sufficient for detection and imaging. The biological relevancy of these new compounds in mice has been assessed, and their biodistribution patterns have been compared. The five-membered ring derivative AMCPy emerged as a potent EPR brain imaging agent while the other two derivatives, AMCPe and DACPy, were quite ineffective.

Acetates↗
PubMedDate not supplied

Role of functional brain imaging in the evaluation of vascular dementia.

There are various types of underlying damage to tissue and vessels in vascular dementia, including (1) single or multiple infarcts that involve association and limbic cortices, (2) small subcortical infarcts disrupting cortico-subcortical circuits, and (3) white matter lesions. The clinical picture of vascular dementia varies, and the role of functional brain imaging of cerebral blood flow and metabolism would be expected to be different among subtypes of vascular dementia. The role and value of functional brain imaging is limited for cortical infarcts; it is very valuable in assessing the impact on cortical function for small subcortical infarcts; and it is probably useful for evaluating white matter lesions, but this needs to be determined in further studies. At least in research of vascular dementia, functional brain imaging criteria should be included for proper patient selection. Careful studies using functional imaging tools in a well-characterized patient population will be needed.

Alzheimer Disease↗