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Functional magnetic resonance imaging (fMRI) of motor deficits in schizophrenia (In German)
JANUARY-MARCH
ABSTRACTS
1996
patterns and demonstrating functional connectivity of interacting areas. Here, we present various strategies for data evaluation by means of correlational analyses that surpass the quality of subtraction-based activation maps by improving both sensitivity and robustness. On a pixel-by-pixel basis the approach correlates signal time courses with a reference function, reflecting the temporal sequence of activated and control states. Extended versions employ the calculation of auto- or cross-correlation functions that increase sensitivity, but require periodic stimulations. Following individual correction for nonspecific but correlated signal fluctuations, mapping of task-related coherent activation can be improved using neighborhood principles. Such refined strategies are expected to enhance the usefulness of oxygenation-sensitive MRl for studying the functional anatomy of the human brain under both physiological and pathological conditions. Authors’ Summary
FUNCI’IONAL MAGNEIX RESONANCE IMAGING OF THE VISUAL CORTM (In German) Briining R, Danek A (Magnetresonanztomographie, Institut f. Radiologische Diagnostik der Universitgt, Klinikum Grosshadern, Marchionistrasse 15, D-81366 Munich, Germany). Radiologe 1995;35:256-262. Functional magnetic resonance imaging (MRI) allows one to directly visualize regional activity of the visual cortex during stimulation. The value of the method to evaluate physiological and pathological conditions is elaborated on in comparison with positron emission tomography (l?F,T). Aspects as sequence selection and stimulus paradigms are discussed. Subtle activity in the primary cortex (Vl),processing areas as MTN5, and subcortical areas are visualized by MRI. Cooperation of the subjects is an essential factor. Despite promising initial results in clinical trials the focus of research in the visual cortex yet remains in the preclinical field. Authors’ Summary
FUNCIXONAL MAGNFXIC RESONANCE IMAGING OF BASAL GANGLIA. ACXIVATION MAPPING m FLASH SEQUENCES FOR BOLD CONTI&T AND HIGH RESOLUTION @n G=man) Seelos KC, Bucher SF, Stehling KK, et al. (Institut f. Radiologische Diagnostik der Universitht,
69
Klinikum Grosshadern, Marchionistrasse 15, D-81377Munich, Germany). Radiologe 1995;35:263-266. The activation pattern of the putamen and internal and external divisions of the globus pallidus was investigated during rapid pronation and supination of the right and left hand in 12 normal volunteers using a fast flow-angle shot (FLASH) sequence with high resolution for functional magnetic resonance imaging (fMRl) at 1.5 T. The chosen paradigm for motor function led to a signal increase within the basal ganglia between 3 and 23 % , depending on the structure and individual subject. In all cases significant activation could be found contralateral to the moving hand. In six cases activation was also found on the ipsilateral side. The activated areas within the putamen and internal and external divisions of the globus pallidus were less than 5 mm*. These first results indicate that fMR1 studies of the basal ganglia are feasible and might be suitable for analyzing basal ganglia disorders. Authors’ Summary
FUNCTIONAL MAGNETIC RESONANCE IMAGING (IMRI) OF MOTOR DEFICITS IN SCHIZOPHRENIA (In German) Wenz F, Baudendinstel K, Knoppo MV, et al. (Abteilung Radiologie, Radiologische Universitatsklinik, Im Neuenheimer Feld 400, D-69120Heidelberg, Germany). Radiologe 1995;35:267-271. Neurological soft signs (NSSs), which are minor motor and sensory deficits, for example, during fingerto-thumb opposition, are frequently found in schizophrenia. The purpose of this study was to investigate differences in the cerebral activation pattern in IO schizophrenic patients and 10healthy volunteers using functional magnetic resonance imaging (fMR1). Methods: fMRI was performed using a modified fast flow-angle shot (FLASH) sequence (TR/TE/a = lOO/ 60/40") and a conventional 1.5-T MR scanner. Colorcoded statistical parametric maps based on Student’s t test were calculated. Activation strength was quantified using a 5 x 6 grid overlay. Results: The volunteers showed a higher activation strength during left hand movement compared to right hand movement. This lateralization effect was reversed in patients who showed overall reduced activation strength. Conclusions: Disturbed interhemispheric balance in schizophrenic patients during motor task performance can
70
AB-
be demonstrated using fMRL These findings support the hypothesis that changes in the sensorimotor cortex may be involved in the development of NSSs. Authors’ Summary
FUNCTIONAL MR MAPPING OF HIGHER COGNITIVE BRAIN FUNCI’IONS (In German) Bellemann ME, Spitzer M, Brix G, et al. (Forschung-schwerpunkt Radiologische Diagnostik u. Therapie, Deutches Krebsforschungszentrum, Im Neuenheimer Feld 280, D-69120 Heidelberg, Germany). Radiologe 1995;35:272-282. Functional magnetic resonance imaging (fMRl) offers a powerful experimental tool for mapping activated cortical regions in man. Thereby, the paramagnetic deoxyhemoglobin in the red blood cells acts as an endogenous susceptibility contrast agent, which allows the noninvasive detection of stimulus-induced transient changes in regional cerebral blood flow and volume. Fifteen normal subjects were examined on a conventional 1.5-T MR system to visualize cortical activation during the performance of high-level cognitive tasks. A computer-controlled videoprojector was employed to present psychometrically optimized activation paradigms. Reaction times and error rates of the volunteers were acquired online during stimulus presentation. The time course of cortical activation was measured in a series of strongly T2 *-weighted gradientecho images from three or four adjacent slices. For anatomical correlation, picture elements showing a stimulus-related significant signal increase were colorcoded and superimposed on n-weighted spin-echo images. Analysis of the fMRI data revealed a subtle (range, 2 to 5%), but statistically significant (p < 0.05) increase in signal intensity during the periods of induced cortical activation. Judgment of semantic relatedness of word pairs, for example, activated selectively cortical areas in left frontal and left temporal brain regions. The strength of cortex activation in the semantic task decreased significantly in the course of stimulus presentation and was paralleled by a decrease in the corresponding reaction times. With its move into the area of cognitive neuroscience, fMRI calls both for the careful design of activation schemes and for the acquisition of behavioral data. For example, brain regions involved in language processing could only be identified clearly when psychometrically matched activation paradigms were employed. The reaction time data correlated well with selective learning and
CLINICAL IMAGING VOL. 20, NO. 1
thus helped to facilitate interpretation of the fMRI data sets. Authors’ Summary
FUNCTIONAL MAGNETIC RESONANCE IMAGING OF PSYCHOLOGICAL FUNCTIONS WITH EXPERIMENTALLY INDUCED EMOTION Qn German) Grodd W, Schneider F, Klose U, Nagele T. (Abteilung f. Neuroradiologie, Radiologische Universittitsklinik, Hoppe-Seyler-Strasse 3, D-72676 Tiibingen, Germany). Radiologe 1995;35:283-289. Changes in regional cerebral blood oxygenation during experimentally modified psychological activation can be measured with functional magnetic resonance imaging (fMRI). fMRl is a new imaging technique for perfusion-based signal intensities of the brain without the necessity of radioactivity and with superior anatomical and temporal resolution compared to positron emission tomography (PET). In this study a T2* fast flow-angle shot (FLASH) sequence (TR 240, TE 60, slice thickness 4 mm, a = 409 matrix 64 x 128) was used to investigate changes in signal intensity within the temporal lobe and the amygdala during experimentally induced emotions. Visual stimuli of happy (sad) facial portraits were presented to volunteers to induce changes in the subjects’ mood while lying in the tomograph. In agreement with a previous PET study, a significant increase in signal intensity in the left amygdala was found during induction of a sad mood, while no comparable effect was visible during induction of a happy mood. Authors’ Summary
MAGNEIIC RESONANCE IMAGING OF BRAIN DEATH Lee DH, Nathanson JA, Fox AJ, et al. (Department of Diagnostic Radiology and Nuclear Medicine, University Hospital, 339 Windermere Road, London, Ontario N6A 5A5, Canada). Can Assoc Radio1 J 1995;46:174-178. OBJECTIVE: To demonstrate the magnetic resonance imaging (MRI) appearance of the brain in patients with clinical brain death. PATIENTS AND METHODS: High-field (1.5-T) MRI was performed on five patients who were subsequently proven clinically brain dead. Conven-
ABSTRACTS
1996
patterns and demonstrating functional connectivity of interacting areas. Here, we present various strategies for data evaluation by means of correlational analyses that surpass the quality of subtraction-based activation maps by improving both sensitivity and robustness. On a pixel-by-pixel basis the approach correlates signal time courses with a reference function, reflecting the temporal sequence of activated and control states. Extended versions employ the calculation of auto- or cross-correlation functions that increase sensitivity, but require periodic stimulations. Following individual correction for nonspecific but correlated signal fluctuations, mapping of task-related coherent activation can be improved using neighborhood principles. Such refined strategies are expected to enhance the usefulness of oxygenation-sensitive MRl for studying the functional anatomy of the human brain under both physiological and pathological conditions. Authors’ Summary
FUNCI’IONAL MAGNEIX RESONANCE IMAGING OF THE VISUAL CORTM (In German) Briining R, Danek A (Magnetresonanztomographie, Institut f. Radiologische Diagnostik der Universitgt, Klinikum Grosshadern, Marchionistrasse 15, D-81366 Munich, Germany). Radiologe 1995;35:256-262. Functional magnetic resonance imaging (MRI) allows one to directly visualize regional activity of the visual cortex during stimulation. The value of the method to evaluate physiological and pathological conditions is elaborated on in comparison with positron emission tomography (l?F,T). Aspects as sequence selection and stimulus paradigms are discussed. Subtle activity in the primary cortex (Vl),processing areas as MTN5, and subcortical areas are visualized by MRI. Cooperation of the subjects is an essential factor. Despite promising initial results in clinical trials the focus of research in the visual cortex yet remains in the preclinical field. Authors’ Summary
FUNCIXONAL MAGNFXIC RESONANCE IMAGING OF BASAL GANGLIA. ACXIVATION MAPPING m FLASH SEQUENCES FOR BOLD CONTI&T AND HIGH RESOLUTION @n G=man) Seelos KC, Bucher SF, Stehling KK, et al. (Institut f. Radiologische Diagnostik der Universitht,
69
Klinikum Grosshadern, Marchionistrasse 15, D-81377Munich, Germany). Radiologe 1995;35:263-266. The activation pattern of the putamen and internal and external divisions of the globus pallidus was investigated during rapid pronation and supination of the right and left hand in 12 normal volunteers using a fast flow-angle shot (FLASH) sequence with high resolution for functional magnetic resonance imaging (fMRl) at 1.5 T. The chosen paradigm for motor function led to a signal increase within the basal ganglia between 3 and 23 % , depending on the structure and individual subject. In all cases significant activation could be found contralateral to the moving hand. In six cases activation was also found on the ipsilateral side. The activated areas within the putamen and internal and external divisions of the globus pallidus were less than 5 mm*. These first results indicate that fMR1 studies of the basal ganglia are feasible and might be suitable for analyzing basal ganglia disorders. Authors’ Summary
FUNCTIONAL MAGNETIC RESONANCE IMAGING (IMRI) OF MOTOR DEFICITS IN SCHIZOPHRENIA (In German) Wenz F, Baudendinstel K, Knoppo MV, et al. (Abteilung Radiologie, Radiologische Universitatsklinik, Im Neuenheimer Feld 400, D-69120Heidelberg, Germany). Radiologe 1995;35:267-271. Neurological soft signs (NSSs), which are minor motor and sensory deficits, for example, during fingerto-thumb opposition, are frequently found in schizophrenia. The purpose of this study was to investigate differences in the cerebral activation pattern in IO schizophrenic patients and 10healthy volunteers using functional magnetic resonance imaging (fMR1). Methods: fMRI was performed using a modified fast flow-angle shot (FLASH) sequence (TR/TE/a = lOO/ 60/40") and a conventional 1.5-T MR scanner. Colorcoded statistical parametric maps based on Student’s t test were calculated. Activation strength was quantified using a 5 x 6 grid overlay. Results: The volunteers showed a higher activation strength during left hand movement compared to right hand movement. This lateralization effect was reversed in patients who showed overall reduced activation strength. Conclusions: Disturbed interhemispheric balance in schizophrenic patients during motor task performance can
70
AB-
be demonstrated using fMRL These findings support the hypothesis that changes in the sensorimotor cortex may be involved in the development of NSSs. Authors’ Summary
FUNCTIONAL MR MAPPING OF HIGHER COGNITIVE BRAIN FUNCI’IONS (In German) Bellemann ME, Spitzer M, Brix G, et al. (Forschung-schwerpunkt Radiologische Diagnostik u. Therapie, Deutches Krebsforschungszentrum, Im Neuenheimer Feld 280, D-69120 Heidelberg, Germany). Radiologe 1995;35:272-282. Functional magnetic resonance imaging (fMRl) offers a powerful experimental tool for mapping activated cortical regions in man. Thereby, the paramagnetic deoxyhemoglobin in the red blood cells acts as an endogenous susceptibility contrast agent, which allows the noninvasive detection of stimulus-induced transient changes in regional cerebral blood flow and volume. Fifteen normal subjects were examined on a conventional 1.5-T MR system to visualize cortical activation during the performance of high-level cognitive tasks. A computer-controlled videoprojector was employed to present psychometrically optimized activation paradigms. Reaction times and error rates of the volunteers were acquired online during stimulus presentation. The time course of cortical activation was measured in a series of strongly T2 *-weighted gradientecho images from three or four adjacent slices. For anatomical correlation, picture elements showing a stimulus-related significant signal increase were colorcoded and superimposed on n-weighted spin-echo images. Analysis of the fMRI data revealed a subtle (range, 2 to 5%), but statistically significant (p < 0.05) increase in signal intensity during the periods of induced cortical activation. Judgment of semantic relatedness of word pairs, for example, activated selectively cortical areas in left frontal and left temporal brain regions. The strength of cortex activation in the semantic task decreased significantly in the course of stimulus presentation and was paralleled by a decrease in the corresponding reaction times. With its move into the area of cognitive neuroscience, fMRI calls both for the careful design of activation schemes and for the acquisition of behavioral data. For example, brain regions involved in language processing could only be identified clearly when psychometrically matched activation paradigms were employed. The reaction time data correlated well with selective learning and
CLINICAL IMAGING VOL. 20, NO. 1
thus helped to facilitate interpretation of the fMRI data sets. Authors’ Summary
FUNCTIONAL MAGNETIC RESONANCE IMAGING OF PSYCHOLOGICAL FUNCTIONS WITH EXPERIMENTALLY INDUCED EMOTION Qn German) Grodd W, Schneider F, Klose U, Nagele T. (Abteilung f. Neuroradiologie, Radiologische Universittitsklinik, Hoppe-Seyler-Strasse 3, D-72676 Tiibingen, Germany). Radiologe 1995;35:283-289. Changes in regional cerebral blood oxygenation during experimentally modified psychological activation can be measured with functional magnetic resonance imaging (fMRI). fMRl is a new imaging technique for perfusion-based signal intensities of the brain without the necessity of radioactivity and with superior anatomical and temporal resolution compared to positron emission tomography (PET). In this study a T2* fast flow-angle shot (FLASH) sequence (TR 240, TE 60, slice thickness 4 mm, a = 409 matrix 64 x 128) was used to investigate changes in signal intensity within the temporal lobe and the amygdala during experimentally induced emotions. Visual stimuli of happy (sad) facial portraits were presented to volunteers to induce changes in the subjects’ mood while lying in the tomograph. In agreement with a previous PET study, a significant increase in signal intensity in the left amygdala was found during induction of a sad mood, while no comparable effect was visible during induction of a happy mood. Authors’ Summary
MAGNEIIC RESONANCE IMAGING OF BRAIN DEATH Lee DH, Nathanson JA, Fox AJ, et al. (Department of Diagnostic Radiology and Nuclear Medicine, University Hospital, 339 Windermere Road, London, Ontario N6A 5A5, Canada). Can Assoc Radio1 J 1995;46:174-178. OBJECTIVE: To demonstrate the magnetic resonance imaging (MRI) appearance of the brain in patients with clinical brain death. PATIENTS AND METHODS: High-field (1.5-T) MRI was performed on five patients who were subsequently proven clinically brain dead. Conven-