[Brain mapping. A computerized brain atlas is an indispensable aid for identification of structure and function].
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Anatomy, Artistic↗
Biomedical subjects
T Greitz
Publications and source records attributed to T Greitz.
The Stockholm School of Neuroradiology.
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History, 20th Century↗
Use of a computerized brain atlas in magnetoencephalographic activation studies.
A pilot study was carried out to test the feasibility of an adjustable computerized brain atlas, adapted to the individual anatomy for localizing current dipoles by means of magnetoencephalography (MEG). The atlas can be adapted to individual computed tomography (CT) or magnetic resonance (MR) images. Position information is transferred between these imaging methods and MEG using a stereotactic technique. For this purpose, a special non-magnetic helmet was designed to be used together with the ordinary head fixation system. It seems likely that the proposed combination of the brain atlas with MEG, CT and MRI methods will become a powerful tool in exploring different brain functions.
Anatomy, Artistic↗
Methodological aspects of brain activation studies: cerebral blood flow determined with [15O]butanol and positron emission tomography.
In this methodological study, a procedure for measuring regional CBF (rCBF) with positron emission tomography and 15O-labelled tracers is optimized. Four healthy volunteers were subjected to eight studies with use of [15O]butanol as a tracer: four times while reading aloud and four times while reading silently from a phonologically balanced list of single words. The gain from these repeated intra-individual studies of the same activation state (fractionation) was demonstrated in terms of noise-equivalent counts in a phantom study. A computerized brain atlas was used to reformat the images to a common anatomical representation, thereby minimizing the effects of inter- and intra-individual anatomical and positional variations. This allowed the formation of inter- and intra-individual average subtraction images with error estimates. Differences between the two activation states were detected with use of an exploratory significance map based on a paired Student's t test. The results compared well with Friston's method of determining levels of statistical significance. No difference was obtained when comparing results from rCBF images and images generated from measurement of uptake of the tracer. The paradigm chosen for activation was shown to yield a constant activation level during the repeated measurements (i.e., no habituation).
Brain↗
Regional cerebral blood flow during experimental phobic fear.
Positron emission tomographic measurements of regional cerebral blood flow (rCBF) were used to investigate central nervous system correlates of fear and anxiety. Volunteers with symptomatic snake phobia were studied while exposed to visual phobogenic, aversive, and neutral stimuli. Anxiety ratings and the number of nonspecific electrodermal fluctuations increased as a function of phobic stimulation. Phobic, compared to neutral and aversive, stimulation elevated rCBF in the visual associative cortex. The basal ganglia were not activated more by phobic than aversive or neutral stimulation. However, cortical and thalamic rCBF were always correlated during phobic but not aversive or neutral stimulation. This indicates that the thalamus could be a relay station for phobic stimulus processing and affect.
Adult↗
The role of anatomic information in quantifying functional neuroimaging data.
When using modern neuroimaging tools, such as CT, PET, SPECT, MRI and MEG, in brain research and brain diagnostics, there is a common need for including external anatomical information into the interpretation and analysis of data. This information may be used to aid the interpretation of structures in images from low resolution imaging tools. With high resolution tools it can help to identify resolved structures. It can also facilitate the merging of data from different modalities, or from different individuals. The anatomical information is often given as regions of interests (ROIs), which may be manually created from an anatomy rich image or automatically created from a standard template collection or from an atlas data base. Automatic methods will lead to a substantial reduction in bias and in size of the systematic errors. Functional ROIs can correspondingly be derived from functional images (usually PET or SPECT). Different aspects of these processes are discussed in the report.
Brain↗
Specification and selection of regions of interest (ROIs) in a computerized brain atlas.
The computerized individually adjustable brain atlas (CBA) has been further developed. The atlas was primarily designed for anatomical localization and quantitative evaluation of data in positron emission tomography (PET), but may also be employed for other neuroimaging modalities, such as transmission computed tomography (CT) and magnetic resonance imaging (MRI). The atlas is based on anatomical information obtained from digitized cryosectioned brains. Using spatially standardized and then averaged MRI images, we demonstrate the high localization accuracy and precision of the brain atlas. This is a prerequisite for obtaining accuracy when using the atlas in the localization and the quantitative evaluation of PET data. The specification and the selection of region of interests (ROIs) by the CBA are presented and discussed.
Brain↗
[Sven-Ivar Seldinger. Severe attack of common sense resulted in a revolutionary catheterization technique].
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Angiography↗
[Linguistics in radiology--a symposium which reflects problems of all medical disciplines].
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Congresses as Topic↗
Accuracy and precision of the computerized brain atlas programme for localization and quantification in positron emission tomography.
The computerized brain atlas programme (CBA) provides a powerful tool for the anatomical analysis of functional images obtained with positron emission tomography (PET). With a repertoire of simple transformations, the data base of the CBA is first adapted to the anatomy of the subject's brain represented as a set of magnetic resonance (MR) or computed tomography (CT) images. After this, it is possible to spatially standardize (reformat) any set of tomographic images related to the subject, PET images, as well as CT and MR images, by applying the inverse atlas transformations. From these reformatted images, statistical images, such as average images and associated error images corresponding to different groups of subjects, may be produced. In all these images, anatomical structures can be localized using the atlas data base and the functional values can be evaluated quantitatively. The purpose of this study was to determine the spatial and quantitative accuracy and precision of the calculated regional mean values. Therefore, the CBA was applied to regional CBF (rCBF) measurements with [11C]fluoromethane and PET on 26 healthy male volunteers during rest and during three different physiological stimulation tasks. First, the spatial accuracy and precision of the reformation process were determined by measuring the spread of defined anatomical structures in the reformatted MR images of the subjects. Second, the mean global CBF and the mean rCBF in the average PET images were compared with the global CBF and rCBF in the original PET images. Our results demonstrate that the reformation process accurately transformed the individual brains of the subjects into the standard brain anatomy of the CBA. The precision of the reformation process had an SD of approximately 1 mm for the lateral dislocation of midline structures and approximately 2-3 mm for the dislocation of the inner and outer brain surfaces. The quantitative rCBF values of the original PET images were accurately represented in the reformatted PET images. Moreover, this study shows that the application of the CBA improves the analysis of functional PET images: (a) The average PET images had a low background noise [0.4 ml/100 g/min +/- 0.7 (SD)] compared to the mean rCBF changes specifically induced by physiological stimulation. (b) The reformatted PET images had a voxel volume of 10.9 mm3. Owing to this high sampling resolution, it was possible to differentiate the mean rCBF changes in adjacent activated fields such as the left motor hand area from the sensory hand area and the left premotor cortex.(ABSTRACT TRUNCATED AT 400 WORDS)
Adult↗
Motor learning in man: a positron emission tomographic study.
We measured regional cerebral blood flow (rCBF) with positron emission tomography to study changes in anatomical structures during the course of learning a complicated finger sequence of voluntary movements. Motor learning was accompanied by rCBF increases in the cerebellum, decreases in all limbic and paralimbic structures, and striatal decreases which changed to striatal increases as the motor skill was learned. Simultaneously, activations of initially contributing non-motor parts of the cerebral cortex vanished. Both cerebellar circuits and striatal circuits appear important for the storage of motor skills in the brain.
Adult↗
Effects of sulpiride and chlorpromazine on regional cerebral glucose metabolism in schizophrenic patients as determined by positron emission tomography.
Positron emission tomography (PET) was used to determine regional brain glucose metabolism in schizophrenic patients (n = 17) before and during neuroleptic treatment. The patients had not been treated with neuroleptics for at least 3 weeks before the first study. All suffered from acute psychotic symptoms and were hospitalized to obtain neuroleptic treatment. After determination of regional brain metabolism without neuroleptic treatment, 11 patients were treated with sulpiride (800 mg/day) and 6 patients were treated with chlorpromazine (400 mg/day) over 5-6 weeks before the second PET investigation. The control group consisted of seven healthy male volunteers, also investigated twice 5 weeks apart. The PET investigation was made with the subject in a resting state. The tracer was uniformly labelled 11C-glucose. The metabolism was determined bilaterally in 15 brain regions cortical, as well as central regions. Metabolic rates differed among the groups. The sulpiride group had lower metabolic rates than the controls and the schizophrenic patients later treated with chlorpromazine. The sulpiride group, in which absolute metabolic rates were determined, were clinically more autistic and chronic than the chlorpromazine group. It was proposed that these facts could explain the lower metabolic rates in the sulpiride group. A significant change in metabolism in relation to drug treatment was only found in one brain region. The selective D2-receptor antagonist sulpiride increased the metabolic rate in the right lentiform nucleus in comparison with the patients treated with chlorpromazine and the controls. Likewise, relative metabolic rates were increased only in the right lentiform nucleus. Negative correlations between intensity of clinical symptoms and metabolism indicated that emotional tone and drive were related to brain metabolism. No correlations were found between drug concentrations and metabolism or clinical symptoms.
Adult↗
A computerized adjustable brain atlas.
A computerized brain atlas, adjustable to the patients anatomy, has been developed. It is primarily intended for use in positron emission tomography, but may also be employed in other fields utilizing neuro imaging, such as stereotactic surgery, transmission computerized tomography (CT) and magnetic resonance imaging (MRI). The atlas is based on anatomical information obtained from a digitized cryosectioned brain. It can be adjusted to fit a wide range of images from individual brains with normal anatomy. The corresponding transformation is chosen so that the modified atlas agrees with a set of CT or NMR images of the patient. The computerized atlas can be used to improve the quantification and evaluation of PET data by: Aiding and improving the selection of regions of interests. Facilitating comparisons of functional image data from different individuals or groups of individuals. Facilitating the comparison of different examinations of the same patient, thus reducing the need of reproducible fixation systems. Providing external a priori anatomical information to be used in the image reconstruction. Improving the attenuation and scatter corrections. Aiding in selecting a suitable patient orientation during the PET study. By applying the inverse atlas transformation to PET data set it is possible to relate the PET information to the anatomy of the reference atlas. Thus reformatted PET data from different patients can be averaged, and averages from different categories of patients can be compared. This procedure will facilitate the identification of statistically significant differences in the PET information from different groups of patients.
Brain↗
PET determination of regional cerebral glucose metabolism in alcohol-dependent men and healthy controls using 11C-glucose.
Regional brain glucose metabolism was determined in 9 male alcohol-dependent inpatients and 12 male healthy controls. All the patients were socially impaired by the alcohol abuse. All the subjects had abstained from alcohol and drugs for more than four weeks before entering the study. Brain glucose metabolism was determined by positron emission tomography (PET) with 11C-glucose as the tracer. Regions of interest were drawn on displayed computed tomographic (CT) images of the brain. Regions were transferred to corresponding PET slices, allowing the determination of regional glucose metabolism. In the healthy volunteers there was a reduction in glucose metabolism with age. In 11 of the 19 brain regions examined, the alcoholics had a 20% to 30% lower glucose metabolism than the controls. This was true for both cortical and subcortical structures. The distribution of relative regional metabolic rates indicated that parietal cortical areas were most affected. Atrophic changes as shown by CT were not correlated to the reduced metabolism in the alcohol-dependent patients.
Adult↗
An adaptor to the Leksell stereotaxic instrument for digital coordinate determination in radiography.
Special perspex adaptors with radiopaque reference structures have been constructed to fit to the Leksell stereotaxic instrument. These structures are visualized on X-ray film in a radiographic examination like angiography or encephalography. The films obtained in two projections at arbitrary angles and focus-film-distances are placed on a digitizing table for the determination of the stereotaxic coordinates of selected targets. The reference structures and the targets are marked with a cursor whereupon a desk top computer performs the calculation of the stereotaxic coordinates. The system allows a rapid, simple and accurate coordinate determination in stereotaxic radiography using the Leksell stereotaxic instrument.
Cerebral Angiography↗
Regional brain glucose metabolism in drug free schizophrenic patients and clinical correlates.
Regional brain glucose metabolism was investigated in healthy volunteers (n = 10) and in drug free schizophrenic patients (n = 20). The metabolism was determined by positron emission tomography (PET) with 11C-glucose as the tracer. Diagnosis of schizophrenia was made according to RDC and DSM III. Eight patients had their first psychotic episode, four patients had a subchronic course and eight patients had a chronic course with an exacerbation of their illness. Computed tomography (CT) of the brain were made in all the subjects. Regions of interest (n = 35) were drawn on displayed CT images and the marked regions were transferred to the corresponding slice of the PET examination. The PET investigation was made in a dimly lit, quiet room with the eyes of the subject covered. The time course of the 11C-glucose uptake was measured by a four ring PET scanner (PC-384-7B). Metabolic rates of glucose varied greatly among the schizophrenic patients investigated. The variance was significantly greater than that of the controls in most regions. Decreases in mean levels of metabolic rates were related to patients with subchronic or chronic courses. Changes in metabolism were not related to previous duration of neuroleptic treatment of the patients. Left-right asymmetries were found in the temporal lobe (area 22) and the basal frontal cortex (area 11), the metabolic rates of the patients being lower on the left side compared to the controls. Asymmetry of the metabolic rate of the amygdala in hebephrenic patients was the opposite of that found in paranoid patients and controls. Negative correlations between regional metabolic rates and autistic or negative symptoms were found. Thus, the lower the metabolic rate was, the more autistic the patient. Metabolic rates were not correlated to atrophic changes of the brain. No basis for a specific alteration in frontal cortical metabolism of schizophrenics was obtained. Changes in regional metabolic rates in schizophrenia are suggested to reflect disturbances in more general mechanisms which are of importance in neuronal function.
Adult↗
Altered relationships between metabolic rates of glucose in brain regions of schizophrenic patients.
Regional brain glucose metabolism was studied with positron emission tomography (PET) in healthy volunteers (n = 9) and schizophrenic patients (n = 15). The patients were in an acute phase of the disease and drug free. Cerebral metabolic rate with 11C-glucose as the tracer (CMRgl) was determined in both cortical and subcortical structures. In the healthy volunteers significant correlations were found between metabolic rates of some regions, but no relationships were found between CMRgl of limbic cortical areas and that of neocortical or subcortical structures. In the patients, high and significant positive correlations were found between metabolic rates in the neocortical areas, the limbic cortical areas and the subcortical areas. The results indicate differences in the neuronal interplay between regions of healthy and schizophrenic subjects. It is proposed that neuronal systems guiding the specificity and diversity in neuronal functions between different brain regions, are abnormal in schizophrenic patients. Such a disturbance may be the basis for the diversity of psychiatric symptoms in schizophrenics.
Adult↗
A method of stereotaxic localization adopted for conventional and digital radiography.
A method for the determination of stereotaxic coordinates in radiography, e.g. angiography, pneumoencephalography or digital vascular radiography, is described. A special localization frame containing radiopaque structures and scales defines a diagnostic coordinate system. This frame is fixed to the X-ray-table prior to the radiographic procedure and two projections are obtained at arbitrary angles to each other. The focus-film distances do not how to be fixed. The target coordinates are then determined either by a simple graphical procedure or with the use of a digitizing x-y-table, by a computer. With the computer method the films are placed on the digitizing table and the target and a few reference points are marked using a cursor. From the relative positions the computer calculates the coordinates. With the special head fixation system, coordinates of structures visualized in radiographic examinations can be transferred to various therapeutic or diagnostic stereotaxic devices.
Angiography↗