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At least 163 records · Page 9Linked to original sources

PubMed1978

A quantitative clinical comparison of three 99mTechnetium labeled brain imaging radiopharmaceuticals.

In a comparison study of three commonly employed 99mTc brain imaging pharmaceuticals, 16 patients with proven brain lesions had imaging performed with DTPA, glucoheptonate, and pertechnetate over a short interval of time. Lesion detectability was assessed by a data processing system which evaluated average lesion-to-background activity ratios for each patient examination. Statistical analysis of the resultant data demonstrated a significant improvement (20%) in lesion-to-background ratio in favor of one hour delayed DTPA images versus two hour delayed pertechnetate images. Comparison of one hour delayed DTPA images with one hour delayed glucoheptonate images did not reveal a significant difference in lesion-to-background ratio. The authors conclude that both Tc-DTPA and Tc-glucoheptonate are superior alternatives to pertechnetate when employed in the manner described.

Brain↗

PubMed1991

Functional brain imaging in the evaluation of psychiatric illness.

In the past century, the field of psychiatry has undergone major changes. During this time, significant advancements in both diagnosis and treatment have occurred. Medical brain imaging using structural and functional brain imaging techniques have contributed, in part, to a better basic understanding of psychiatric disease and to an improving diagnostic approach. Computed tomography and magnetic resonance imaging have supplied limited, but useful insight regarding structural alterations in schizophrenia and the affective disorders. Position emission tomography imaging has already made a major contribution in the assessment of schizophrenia and affective disorders. Single-photon emission computed tomography (SPECT), which is currently more widely available, should contribute more to psychiatric disease evaluation in the future. Recent advances in SPECT technology in the areas of improved instrumentation--such as multidetector and ring detector systems and new radiopharmaceuticals including new rCBF markers and receptor site imaging agents--have contributed to significant improvements in the SPECT imaging technique. At the present time, SPECT has been shown to be feasible and useful in the evaluation of acute and chronic psychiatric and demented states. As SPECT technology continues to evolve, further refinements in this diagnostic capability can be anticipated.

Brain↗

PubMed1975

Glycopyrrolate in 99mTc-pertechnetate brain imaging.

Glycopyrrolate, a synthetic anticholinergic agent, was administered parenterally to two groups of patients referred for 99mTc-pertechnetate brain imaging to assess its ability to suppress pertechnetate uptake by the choroid plexus, oral mucosa, and salivary (parotid) glands. Pertechnetate activity was almost completely eliminated from the choroid plexus and mouth and appeared to be moderately reduced in the parotid gland. The drug can be given orally and may prove valuable in pertechnetate brain imaging.

Brain↗

PubMed1991

User-friendly image processing software tools: general purpose features and application to the correlation of PET-CT brain images.

An interactive software package, performing some useful general purpose image processing operations and being used as a tool for the problem of the anatomical correlation of PET brain images, is under development. The software is developed as a comprehensive tool with a graphic user-interface allowing the display of the processed images through the use of a variety of colormaps. The implemented routines perform a lot of processing operations on the images: a) Local image processing, i.e. smoothing and sharpening, contours extraction, interactive expansion, shrinking and thresholding of the gray scale, histogram equalization. b) ROI handling, i.e., ROI drawing and computing, transformation of an image to a ROI, ROI editing. c) Additional operators include frequency space image processing such as FFT.

Brain↗

PubMed2005

Brain imaging findings in neuropathic pain.

The contribution of brain imaging technologies to the understanding of mechanisms underlying clinical neuropathic conditions is discussed in this article. Available technologies, their advantages, and contributions also are presented. The brain regions involved in acute pain are contrasted to chronic pain and the implications of these differences are discussed. Overall, the reasons for the limited contribution of these techniques to the science of chronic pain are presented in this article.

Brain↗

PubMed2003

Brain imaging studies in mood and anxiety disorders: special emphasis on the amygdala.

Human studies attempting to elucidate brain functioning in health and disease are crucial for our understanding of neuropsychiatric disorders. In the past, scientists relied heavily on neurological lesion studies to understand the functional roles of brain areas. In the last few decades, brain imaging research has made it possible to investigate the molecular and synaptic neuronal events as well as the functioning of neuronal networks in vivo, in patients with neuropsychiatric illnesses. In this context, the functional role of the amygdala has been a focus of neuroimaging studies by leading researchers. Several of these researchers presented papers at a conference, entitled The Amygdala in Brain Function: Basic and Clinical Approaches, that provided the basis for this volume. These papers follow this review in the current volume. The present paper briefly summarizes the highlights of the different presentations, focusing on the functional diversity of the amygdala and its role in different neuropsychiatric disorders; reviews the various brain imaging technologies currently available; and discusses the major findings on the pathophysiology and treatment of depression, bipolar disorder, and anxiety disorders.

Amygdala↗

PubMed1994

Display of merged multimodality brain images using interleaved pixels with independent color scales.

UNLABELLED: This article reviews common methods for two-dimensional display of registered multimodality brain images and describes a software package for presentation of merged MRI and PET images that runs on a workstation with an eight-bit color display. The software package displays merged brain images from multiple modalities in a way that is readily manipulated, visually pleasing and easy to interpret. The display method used, i.e., interleaving of alternate pixels with independent color scales, is effective in producing merged images with high contrast-detail for each volume. Interleaving images from different volumes creates unusual perceptual effects, one of which is the apparent camouflage of low-contrast signals by high values in the paired volume. METHODS: The camouflage effect was thought to arise from perceptual merging of adjacent pixels. An observer experiment was conducted to investigate this tendency of high-activity PET data to obscure low-contrast detail in interleaved MRI data in spite of the digital independence of neighboring pixels. Four observers were presented with 20 combinations of signal plus background targets with uniform mask images, using a two-alternative forced-choice experimental design with 50 trials per combination. RESULTS: The psychophysical evaluation of the ability of human observers to detect the simple test objects in an interleaved image presentation indicated a statistically significant camouflage effect of one volume on the other for some combinations of target and mask. The concept of perceptual merging of adjacent pixels was able to predict which combinations caused the greatest degradations in performance. CONCLUSIONS: The image interleaving approach to the display of two-dimensional slices from registered image volumes makes efficient use of an eight-bit color display. Contrast resolution of both individual volumes is high compared with that in other techniques and the volumes are presented in familiar color scales. However, the method yields an unexpected camouflage effect that tends to obscure low-contrast signals. The practical effect of such camouflage on the interpretation of clinical images remains to be investigated.

Brain↗

PubMedDate not supplied

Acutely administered haloperidol-induced widespread reduction of regional cerebral blood flow observed from subtraction of brain imaging with single photon emission computed tomography using technetium-99m hexamethyl-propyleneamine oxime.

Changes in brain images with single photon emission computed tomography (SPECT) using technetium-99m hexamethyl-propyleneamine oxime (99mTc HMPAO) before and after intramuscular injection of haloperidol (0.08 mg/kg) were studied in 2 unmedicated schizophrenic patients and 2 normal controls by a new technique, i.e. subtraction of brain images. The haloperidol injection reduced regional cerebral blood flow extensively in the bilateral cerebral hemispheres in one of the schizophrenics and one of the normal controls, with little or no haloperidol-induced effects in the remaining 2 subjects. The widespread cortical reduction is considered to be due to a nonspecific or indirect effect of haloperidol in view of the broad action sites inconsistent with the known anatomy of the mesocortical dopaminergic system.

Acute Disease↗

PubMed2001

New strategies for embedding, orientation and sectioning of small brain specimens enable direct correlation to MR-images, brain atlases, or use of unbiased stereology.

We present a newly developed brain slicing machine and technique for tissue embedding, which enable orientation of fresh or fixed brain tissue from small laboratory animals, in any given position, and subsequent tissue sectioning into slabs with an optional thickness between 0.5 and 20 mm. The oriented tissue slabs may be analysed directly, or processed further on a cryostat or vibratome, into thin stainable histological sections, and aligned to MR-images or brain atlases, depending on the reference used for the initial orientation. Additionally, we describe a new embedding medium (HistOmer) which is an alginate cold polymer ready for instant use after mixing with water. HistOmer allows accurate positioning of the tissue during embedding, and at the same time supports and protects the embedded tissue during sectioning. HistOmer is, therefore, described comprehensively and compared with other commonly used embedding media. This novel slicing technique may also, as illustrated, be used to perform isotropic random orientation of the embedded tissue, before sectioning into tissue slabs of the same thickness. The technique thereby fulfills the requirements for optimal tissue sampling and preparation needed for an unbiased stereologic analysis.

Alginates↗

PubMed2001

Human brain imaging in the upright position.

The authors obtained brain images with patients in the upright position using a newly designed and constructed vertical MR system. They found little gravitational effect on brain structures, even in the case of a severely atrophied brain. Their vertical system was practical for routine clinical usage and might provide information regarding gravitational effects on regional perfusion and other aspects of brain physiology.

Adult↗

PubMed1999

Leads for the development of neuroprotective treatment in Parkinson's disease and brain imaging methods for estimating treatment efficacy.

Patients suffering from Parkinson's disease display severe and progressive deficits in motor behavior, predominantly as a consequence of the degeneration of dopaminergic neurons, located in the mesencephalon and projecting to striatal regions. The cause of Parkinson's disease is still an enigma. Consequently, the pharmacotherapy of Parkinson's disease consists of symptomatic treatment, with in particular L-dihydroxyphenylalanine (L-DOPA) and/or dopamine receptor agonists. These induce a dramatic initial improvement. However, serious problems gradually develop during long-term treatment. Therefore, a more rational, c.q. causal treatment is needed which requires the introduction of compounds ameliorating the disease process itself. The development of such compounds necessitates (1) more information on the etiopathogenesis, i.e., the cascade of events that ultimately leads to degeneration of the dopaminergic neurons, and (2) brain imaging methods, to estimate the extent of the degeneration of the dopaminergic neurons in the living patient. This is not only important for the early diagnosis, but will also allow to monitor the effectiveness of alleged neuroprotective compounds on a longitudinal base. In this paper, etiopathogenic mechanisms are highlighted along the line of the oxidative stress hypothesis and within this framework, attention is mainly focused on the putative role of glutathione, dopamine auto-oxidation and phase II biotransformation enzymes. Especially, drugs able to increase the activity of phase II biotransformation enzymes seem to elicit a broad-spectrum (neuro)protective response and look very promising leads for the development of neuroprotective treatment strategies in Parkinson's disease. New developments in brain imaging methods (single photon emission computed tomography (SPECT) and positron emission tomography (PET)) to visualize the integrity of the striatal dopaminergic neurons in humans are highlighted as well. Especially, the introduction of radioligands that bind selectively to the dopamine transporter seems to be a significant step forward for the early diagnosis of Parkinson's disease. Performing these brain imaging studies with fixed time intervals does not only create the possibility to follow the degeneration rate of the dopaminergic neurons in Parkinson's disease but also provides the opportunity to estimate therapeutic effects of putative neuroprotective agents in the individual patient.

Brain↗

PubMed2003

Brain imaging studies of the anatomical and functional consequences of preterm birth for human brain development.

Premature birth can have devastating effects on brain development and long-term functional outcome. Rates of psychiatric illness and learning difficulties are high, and intelligence on average is lower than population means. Brain imaging studies of infants born prematurely have demonstrated reduced volumes of parietal and sensorimotor cortical gray matter regions. Studies of school-aged children have demonstrated reduced volumes of these same regions, as well as in temporal and premotor regions, in both gray and white matter. The degrees of these anatomical abnormalities have been shown to correlate with cognitive outcome and with the degree of fetal immaturity at birth. Functional imaging studies have shown that these anatomical abnormalities are associated with severe disturbances in the organization and use of neural systems subserving language, particularly for school-aged children who have low verbal IQs. Animal models suggest that hypoxia-ischemia may be responsible at least in part for some of the anatomical and functional abnormalities. Increasing evidence suggests that a host of mediators for hypoxic-ischemic insults likely contribute to the disturbances in brain development in preterm infants, including increased apoptosis, free-radical formation, glutamatergic excitotoxicity, and alterations in the expression of a large number of genes that regulate brain maturation, particularly those involved in the development of postsynaptic neurons and the stabilization of synapses. The collaboration of both basic neuroscientists and clinical researchers is needed to understand how normal brain development is derailed by preterm birth and to develop effective prevention and early interventions for these often devastating conditions.

Brain↗

PubMed2006

Dense deformation field estimation for atlas-based segmentation of pathological MR brain images.

Atlas registration is a recognized paradigm for the automatic segmentation of normal MR brain images. Unfortunately, atlas-based segmentation has been of limited use in presence of large space-occupying lesions. In fact, brain deformations induced by such lesions are added to normal anatomical variability and they may dramatically shift and deform anatomically or functionally important brain structures. In this work, we chose to focus on the problem of inter-subject registration of MR images with large tumors, inducing a significant shift of surrounding anatomical structures. First, a brief survey of the existing methods that have been proposed to deal with this problem is presented. This introduces the discussion about the requirements and desirable properties that we consider necessary to be fulfilled by a registration method in this context: To have a dense and smooth deformation field and a model of lesion growth, to model different deformability for some structures, to introduce more prior knowledge, and to use voxel-based features with a similarity measure robust to intensity differences. In a second part of this work, we propose a new approach that overcomes some of the main limitations of the existing techniques while complying with most of the desired requirements above. Our algorithm combines the mathematical framework for computing a variational flow proposed by Hermosillo et al. [G. Hermosillo, C. Chefd'Hotel, O. Faugeras, A variational approach to multi-modal image matching, Tech. Rep., INRIA (February 2001).] with the radial lesion growth pattern presented by Bach et al. [M. Bach Cuadra, C. Pollo, A. Bardera, O. Cuisenaire, J.-G. Villemure, J.-Ph. Thiran, Atlas-based segmentation of pathological MR brain images using a model of lesion growth, IEEE Trans. Med. Imag. 23 (10) (2004) 1301-1314.]. Results on patients with a meningioma are visually assessed and compared to those obtained with the most similar method from the state-of-the-art.

Brain↗

PubMed2006

Brain imaging in psychiatry - a study of 435 psychiatric in-patients at a university clinic.

OBJECTIVE: The use of brain imaging in psychiatry still lacks clear guidelines. We investigated the referral practice, outcome and predictive factors of neuroimaging in a Swiss psychiatric university clinic. METHOD: Medical files were reviewed retrospectively for 435 consecutively hospitalized patients who were subjected to neuroimaging. The association between the sociodemographic and clinical characteristics and the scan results was analyzed using bivariate and multivariate analyses. RESULTS: Of overall examinations, 69.4% were normal, 16.3% equivocal and 14.3% abnormal; 2.9% of scans ordered for screening only showed pathology. Neurologic signs and advanced age of patients predicted abnormal scan findings, whereas other variables such as EEG results showed no significant association. CONCLUSION: Our results support the need for clear indications for using brain imaging in psychiatric in-patients. Focal neurologic signs and advanced patient age seems to predict abnormal scan results. However, these criteria are not sufficiently sensitive to predict significant scan findings in all patients.

Adult↗

PubMed2000

Robust estimation of the probabilities of 3-D clusters in functional brain images: application to PET data.

Recently, we presented a method (the CS method) for estimating the probability distributions of the sizes of supra threshold clusters in functional brain images [Ledberg A, Akerman S, Roland PE. 1998. Estimating the significance of 3D clusters in functional brain images. NeuroImage 8:113-128]. In that method, the significance of the observed test statistic (cluster size) is assessed by comparing it with a sample of the test statistic obtained from simulated statistical images (SSIs). These images are generated to have the same spatial autocorrelation as the observed statistical image (t-image) would have under the null hypothesis. The CS method relies on the assumptions that the t-images are stationary and that they can be transformed to have a normal distribution. These assumptions are not always valid, and thus limit the applicability of the method. The purpose of this paper is to present a modification of the previous method, that does not depend on these assumptions. This modified CS method (MCS) uses the residuals in the linear model as a model of a dataset obtained under the null hypothesis. Subsequently, datasets with the same distribution as the residuals are generated, and from these datasets the SSIs are derived. These SSIs are t-distributed. Thus, a conversion to normal distribution is no longer needed. Furthermore, no assumptions concerning the stationarity of the statistical images are needed. The MCS method is validated on both synthetical images and PET images and is shown to give accurate estimates of the probability distribution of the cluster size statistic.

Brain↗

PubMed1998

Putaminal infarct in methanol intoxication: case report and role of brain imaging studies.

Methanol toxicity can cause severe central nervous system insult in which a characteristic pattern of bilateral putaminal injury is noted on brain imaging studies. We present a fatal case of subacute methanol toxicity with associated diffuse brain involvement, including bilateral putaminal necrosis and cerebral edema with ventricular compression. Theoretical basal ganglia toxicologic mechanisms of methanol poisoning are reviewed, and the role of brain imaging studies will regard to diagnosis, prognosis and impact on management is discussed.

Adult↗

PubMedDate not supplied

A brain image database for structure/function analysis.

BACKGROUND AND PURPOSE: Lesion-deficit-based structure-function analysis has traditionally been empirical and nonquantitative. Our purpose was to establish a new brain image database (BRAID) that allows the statistical correlation of brain functional measures with anatomic lesions revealed by clinical brain images. METHODS: Data on 303 participants in the MR Feasibility Study of the Cardiovascular Health Study were tested for lesion/deficit correlations. Functional data were derived from a limited neurologic examination performed at the time of the MR examination. Image data included 3D lesion descriptions derived from the MR examinations by hand segmentation. MR images were normalized in-plane using local, linear Talairach normalization. A database was implemented to support spatial data structures and associated geometric and statistical operations. The database stored the segmented lesions, patient functional scores, and several anatomic atlases. Lesion-deficit association was sought by contingency testing (chi2-test) for every possible combination of each neurologic variable and each labeled atlas structure. Significant associations that confirmed accepted lesion-deficit relationships were sought. RESULTS: Two-hundred thirty-five infarctlike lesions in 117 subjects were viewed collectively after mapping into Talairach cartesian coordinates. Anatomic structures most strongly correlated with neurologic deficits tended to be situated in anatomically appropriate areas. For example, infarctlike lesions associated with visual field defects were correlated with structures in contralateral occipital structures, including the optic radiations and occipital gyri. CONCLUSION: Known lesion-deficit correlations can be established by a database using a standard coordinate system for representing spatial data and incorporating functional and structural data together with appropriate query mechanisms. Improvements and further applications of this methodology may provide a powerful technique for uncovering new structure-function relationships.

Brain↗

PubMed2002

Functional brain imaging in the dementias: role in early detection, differential diagnosis, and longitudinal studies.

This review considers the role of functional brain imaging techniques in the dementias. The substantial assistance that especially single-photon emission tomography and positron emission tomography can play in the initial diagnosis of dementia and in the differential diagnosis of the specific dementing disorder is discussed. These techniques alone essentially match the sensitivity and specificity of clinical diagnoses in distinguishing Alzheimer's dementia (AD) from age-matched controls, from frontal lobe dementia and vascular dementia, and even from Lewy body dementia. Newer analytic techniques such as voxel-based correlational analyses and discriminant function analyses enhance the power of such differential diagnoses. Functional brain imaging techniques can also significantly assist in patient screening for clinical trials. The correlation of the observed deficits with specific patterns of cognitive abnormalities permits enhanced patient management and treatment planning and improved longitudinal assessment of outcome. It is also noteworthy that the classic abnormalities of temporoparietal and posterior cingulate hypoperfusion or hypometabolism appear to be present prior to symptom onset. These abnormalities predict progression to AD in the presence of the earliest of symptoms, and are present even in cognitively normal but at-risk subjects, with a severity proportional to the risk status. Even greater predictive ability for progression to AD is obtained by combining measures of perfusion or metabolism with risk factors, tau protein levels, hippocampal N-Acetyl aspartate concentrations, or hippocampal volume measures.

Alzheimer Disease↗