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  • 1
    ISSN: 1432-1459
    Keywords: Positron emission tomography ; Cerebellar diaschisis ; Pontine haematoma ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Cerebellar glucose metabolism was studied in one patient with a hemipontine haematoma in order to investigate remote metabolic effects within the cerebellar lobules. In the patient, who suffered a circumscribed hemipontine haemorrhage, and in three normal subjects cerebellar glucose metabolisms was studied using18F-2-fluoro-2-deoxy-d-glucose and high-resolution positron emission tomography (PET). Regions of interest were placed on sagittal brain slices of co-registered magnetic resonance images for quantitative evaluation of glucose metabolism in each cerebellar lobule. Interruption of corticopontine fibres caused inactivation of pontine nuclei with subsequent contralateral cerebellar diaschisis, mainly in the anterior lobe and the posterior portion of the quadrangular lobule. Damage within the ponto-cerebellar part of the cortico-ponto-cerebellar pathway, e.g. pontine nuclei and crossing ponto-cerebellar fibres from contralateral pontine nuclei, led to ipsi- and contralateral cerebellar diaschisis within the semilunar, gracile and biventral lobules. High-resolution PET is capable of demonstrating bilateral diaschisis involving specific cerebellar lobules to a different degree that is consistent with the pontine anatomy of the cortico-ponto-cerebellar pathway and with the location of the haemorrhagic lesion.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1920
    Keywords: Brain, MR ; Positron imaging ; Dementia ; Metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We compared the correlation of PET and MRI with neuropsychological tests in 26 patients with probable Alzheimer's disease (AD). The width of the temporal horns and the third ventricle, regional metabolic rates of glucose (rCMRGlu) and the proportion of cerebrospinal fluid space in mesial temporal and temporoparietal cortical regions were measured with three-dimensionally coregistered PET and MRI in two planes perpendicular to the Sylvian fissure. Highly significant correlations between rCMRGlu and neuropsychological tests were found mainly in the temporoparietal cortex, with and without correction for atrophy. Correlations of similar magnitude were seen also between most tests and the width of the temporal horns and third ventricle. Changes in the third ventricle and mesial temporal lobe were best seen with MRI, whereas PET most clearly depicted alterations in neocortical association areas. These two aspects of the disease correlated with the severity of dementia to a similar degree.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1920
    Keywords: Key words Brain ; MR ; Positron imaging ; Dementia ; Metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We compared the correlation of PET and MRI with neuropsychological tests in 26 patients with probable Alzheimer's disease (AD). The width of the temporal horns and the third ventricle, regional metabolic rates of glucose (rCMRGlu) and the proportion of cerebrospinal fluid space in mesial temporal and temporoparietal cortical regions were measured with three-dimensionally coregistered PET and MRI in two planes perpendicular to the Sylvian fissure. Highly significant correlations between rCMRGlu and neuropsychological tests were found mainly in the temporoparietal cortex, with and without correction for atrophy. Correlations of similar magnitude were seen also between most tests and the width of the temporal horns and third ventricle. Changes in the third ventricle and mesial temporal lobe were best seen with MRI, whereas PET most clearly depicted alterations in neocortical association areas. These two aspects of the disease correlated with the severity of dementia to a similar degree.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1433-0407
    Keywords: Schlüsselwörter Depression ; Hirnperfusion ; 99mTc- HMPAO-SPECT ; Schlafentzugsbehandlung ; Remission ; Key words Major depression ; Brain SPECT ; Sleep deprivation ; Recovery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary The objective of this study was to investigate the relationship between the effect of sleep deprivation, recovery and regional brain perfusion in patients with major depression. Regional cerebral blood flow was assessed by 99mTc-HMPAO-SPECT before and after sleep deprivation in fourteen medicated patients. Three of the patients underwent a follow-up measurement after clinical recovery and with an unchanged antidepressant medication. Before sleep deprivation the responding patients had a significantly higher anterior cingulate perfusion than the nonresponding patients, that normalized after sleep deprivation. Cingulate perfusion uniquely differentiated eventual treatment response from non-responders, as perfusion in no other region under study discriminated the two groups. At baseline all patients revealed hypoperfusion in the left prefrontal cortex when compared to the right side, which was not affected by sleep deprivation, whereas prefrontal hypoperfusion was reversible upon remission. These findings are in agreement with previous PET investigations and provide evidence for cingulate and prefrontal dysfunction associated with depression, that are reversible by successful treatment and may represent state markers.
    Notes: Zusammenfassung Im akuten Stadium einer endogenen Depression unterzogen sich 14 Patienten vor und nach einer totalen Schlafentzugsbehandlung einer Hirnuntersuchung mittels 99mTc-HMPAO-SPECT. Zusätzlich wurden erstmals auch 3 dieser Patienten unter unveränderter Medikation im Stadium der klinischen Remission untersucht. Alle Patienten zeigten in beiden Untersuchungen während der Akutphase eine regionale Perfusionsasymmetrie im präfrontalen Kortex mit signifikant niedrigeren Werten linksseitig, die im Stadium der klinischen Remission nicht mehr nachweisbar waren. Nur bei den Patienten, die auf den totalen Schlafentzug mit einer erheblichen Stimmungsaufhellung reagierten, fanden sich vor der Behandlung signifikant höhere Perfusionswerte im anterioren Cingulum als bei den Nonrespondern, die sich nach der Schlafentzugsbehandlung normalisierten. Bei den Patienten, die klinisch nicht mit einer Stimmungsverbesserung reagierten, zeigte sich keine Perfusionsänderung nach dem Schlafentzug. Auch mit SPECT lassen sich funktionelle Beeinträchtigungen im präfrontalen Kortex und im Cingulum während der akuten endogenen Depression nachweisen, die unter einer erfolgreichen Therapie reversible zu sein scheinen und „state marker” darstellen könnten.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1619-7089
    Keywords: Brachytherapy ; Glioma ; Positron emission tomography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We investigated whether 2-[18F]-fluoro-2-de-oxy-d-glucose (FDG) and carbon-11 methionine are suitable tracers to monitor the effects of therapy for low-grade gliomas. Ten patients with low-grade glioma without previous treatment were studied with FDG positron emission tomography. Additionally,l-[methyl-11C]-methionine uptake was measured in five subjects before and 1 year after computerized tomography (CT)-guided stereotactic and computer-assisted implantation of iodine-125 seeds. All scans were 3D-matched to CT, isodose volumes were determined, and changes in glucose metabolism and methionine uptake were evaluated in tumour and brain tissue as a function of radiation dose. After 1 year glucose metabolism was not significantly altered up to a radiation dose of 300 Gy, whereas methionine uptake showed a significant dose-dependent decrease. Higher rates of decline were found in tumours with high basal methionine incorporation activity before therapy. These data suggest that measurement of methionine uptake is more suitable than measurement of FDG uptake for monitoring therapeutic effects in low-grade gliomas.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1619-6937
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary We investigate the flow through a porous medium both numerically and experimentally. The computer simulation solves a generalized non-linear extension to Darcy's law, known as Darcy-Brinkman-Lapwood-Forchheimer (DBLF) equation in a way that allows us to estimate the significance of each term in this equation. The numerical results have been validated against tracer transport data obtained using positron emission tomography (PET), a novel, non-invasive technique for flow-visualization. The results indicate that viscous diffusion is of significance over a narrow region, “the Brinkman-layer”, below the fluid-sediment interface, and that the Darcy equation alone is not sufficient to estimate the advective transport correctly.
    Type of Medium: Electronic Resource
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