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  • Positron emission tomography  (6)
  • Proton magnetic resonance spectroscopic imaging  (2)
  • 18F-fluorodeoxyglucose  (1)
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  • 1
    Electronic Resource
    Electronic Resource
    Positron emission tomographical studies of 1-11C-acetoacetate, 2-18F-fluoro-deoxy-D-glucose, and L-1-11C-tyrosine uptake by cat brain with an experimental lesion (1989)
    Springer
    Acta neurochirurgica 99 (1989), S. 166-172 
    Details
    ISSN: 0942-0940
    Keywords: Positron emission tomography ; 18F-fluorodeoxyglucose ; ketone bodies ; 11C-tyrosine ; brain oedema ; blood-brain barrier
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In cat brain with a freezing injury, the uptake of 1-11C-acetoacetate (11C-ACAC), 2-18F-fluorodeoxy-D-glucose (18FDG), and L-1-11C-tyrosine (11C-TYR) was monitored by positron emission tomography following intravenous administration of the tracers, at 1 day and 1–3 weeks after the injury. The development and further course of the cold-induced oedema was monitored by magnetic resonance imaging. In the fresh (1 day old) lesion there was increased uptake of11C-ACAC, probably due to release of the restrictive influence of the blood-brain barrier upon passage of the substance into brain. The uptake of18FDG, which normally occurs by carrier-mediated transport at the barrier, was decreased in the fresh lesion, probably as a result of damage of the carrier mechanism. In the 3 week old lesion18FDG uptake was still reduced, and11C-ACAC uptake was still increased, although barrier function to Evans blue had recovered. It is suggested, that the increased11C-ACAC uptake in the chronic lesion bears upon the proliferation of macrophages and reactive glial cells in the lesion. This is supported by the increased uptake of11C-TYR in the 2 weeks old lesion, while in the fresh lesion11C-TYR uptake was unchanged.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01402328
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Localised proton spectroscopy and spectroscopic imaging in cerebral gliomas, with comparison to positron emission tomography (1995)
    Springer
    Neuroradiology 37 (1995), S. 198-206 
    Details
    ISSN: 1432-1920
    Keywords: Gliomas ; Proton magnetic resonance spectroscopy ; Proton magnetic resonance spectroscopic imaging ; Brain oedema ; Positron emission tomography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In 32 patients with gliomas, one- and two-dimensional proton magnetic resonance spectroscopy (1H-MRS) has been conducted, the latter allowing reconstruction of spectroscopic data into a spectroscopic image (MRSI), showing the distribution of the various metabolite concentrations over the cross-sectional plane. For lack of absolute concentrations, the measured concentrations of phosphocholine (CHOL),N-acetyl-L-aspartate (NAA), and lactate (LAC) were conventionally expressed in ratios relative to that of creatine (CREAT). Compared to normal brain tissue, an increased CHOL/CREAT ratio was found in all groups of tumours, in glioblastomas, high-, middle- and low-grade astrocytomas both at the margin and the core of the tumours, but in oligodendrogliomas only at the margin. This is consistent with an increased phosphocholine turnover in relation to membrane biosynthesis by the proliferating cells. The NAA/CREAT ratio was decreased in all groups of tumours, both in the centre and at the margin, reflecting replacement of functioning neurons by neoplastic cells. The LAC/ CREAT ratio was elevated in the core of malignant gliomas, which may be the result of a prevailing glycolysis, characteristic of tumours, possibly in conjunction with hypoxia/ischaemia. In the perifocal oedema, there was neither elevation of the CHOL/CREAT ratio nor decrease of the NAA/CREAT ratio; an increased LAC/CREAT ratio therefore rather reflected ischaemia/hypoxia probably due to locally elevated pressure and compromised regional perfusion. In the normal brain, the metabolite ratios of grey matter did not differ from those of white matter. The frontal lobe and basal ganglia showed lower NAA/CREAT ratios than the other cerebral areas. In 7 patients positron emission tomography was also performed with [18F]fluoro-2-deoxy-D-glucose (18FDG) or L-[1-11C]-tyrosine (11C-TYR); the latter demonstrated a pattern of11C-TYR uptake similar to that of CHOL elevation in the MRSI.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01578258
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Localised proton spectroscopy and spectroscopic imaging in cerebral gliomas, with comparison to positron emission tomography (1995)
    Springer
    Neuroradiology 37 (1995), S. 198-206 
    Details
    ISSN: 1432-1920
    Keywords: Key words Gliomas ; Proton magnetic resonance spectroscopy ; Proton magnetic resonance spectroscopic imaging ; Brain oedema ; Positron emission tomography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In 32 patients with gliomas, one- and two-dimensional proton magnetic resonance spectroscopy (1H-MRS) has been conducted, the latter allowing reconstruction of spectroscopic data into a spectroscopic image (MRSI), showing the distribution of the various metabolite concentrations over the cross-sectional plane. For lack of absolute concentrations, the measured concentrations of phosphocholine (CHOL), N -acetyl-L-aspartate (NAA), and lactate (LAC) were conventionally expressed in ratios relative to that of creatine (CREAT). Compared to normal brain tissue, an increased CHOL/CREAT ratio was found in all groups of tumours, in glioblastomas, high-, middle- and low-grade astrocytomas both at the margin and the core of the tumours, but in oligodendrogliomas only at the margin. This is consistent with an increased phosphocholine turnover in relation to membrane biosynthesis by the proliferating cells. The NAA/CREAT ratio was decreased in all groups of tumours, both in the centre and at the margin, reflecting replacement of functioning neurons by neoplastic cells. The LAC/CREAT ratio was elevated in the core of malignant gliomas, which may be the result of a prevailing glycolysis, characteristic of tumours, possibly in conjunction with hypoxia/ischaemia. In the perifocal oedema, there was neither elevation of the CHOL/CREAT ratio nor decrease of the NAA/CREAT ratio; an increased LAC/CREAT ratio therefore rather reflected ischaemia/hypoxia probably due to locally elevated pressure and compromised regional perfusion. In the normal brain, the metabolite ratios of grey matter did not differ from those of white matter. The frontal lobe and basal ganglia showed lower NAA/CREAT ratios than the other cerebral areas. In 7 patients positron emission tomography was also performed with [18F]fluoro-2-deoxy-D-glucose (18FDG) or L-[1-11C]-tyrosine (11C-TYR); the latter demonstrated a pattern of 11C-TYR uptake similar to that of CHOL elevation in the MRSI.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01578258
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Neurotransmitter positron emission tomographic-studies in adults with phenylketonuria, a pilot study (1996)
    Springer
    European journal of pediatrics 155 (1996), S. S78 
    Details
    ISSN: 1432-1076
    Keywords: Key words Phenylketonuria ; Positron emission tomography ; Dopamine D2-receptor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Patients with phenylketonuria (PKU) may suffer from cognitive and neurological deficits which are related to reduced intracerebral concentrations of catecholamines. The function of phenylalanine (Phe) as an inhibitor of the uptake of the precursor amino acid tyrosine (Tyr) through the blood-brain barrier as well as an inhibitor of the expression of dopamine receptors in the brain is under investigation. Positron emission tomography (PET) is a method for quantitatively determining biochemical and physiological processes in vivo. In the current pilot study, l-[1-11C]-Tyr and 18F-fluoro-ethyl-spiperone (FESP) have been used. The metabolic pathway of carboxylic labelled Tyr is mainly incorporation into protein. From the measured tissue and plasma activity as a function of time in combination with a compartimental model the Protein Synthesis Rate (PSR) for Tyr can be calculated. FESP is a ligand which binds irreversibly to the dopamine D2-receptor and has also a low non specific binding, although affinity to the serotonin receptor has been described. The ratio of FESP concentration in striatum and in cerebellum is a measure of the receptor status in vivo. In patients with plasma Phe levels above the maximum therapeutic concentration (〉 700 μmol/l) the PSR for Tyr was decreased as compared to controls and patients with plasma Phe concentrations within the therapeutic range, indicating a decreased availability of Tyr for neurotransmitter synthesis, and hence explaining the reduced cerebral concentration of catecholamines.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00014257
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Brain activity related to serial cognitive performance resembles circuitry of higher order motor control (1996)
    Springer
    Experimental brain research 109 (1996), S. 136-140 
    Details
    ISSN: 1432-1106
    Keywords: Cognitive performance ; Positron emission tomography ; Supplementary motor area ; Parietal cortex ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Differences between two states of cerebral activation were studied in eight subjects by positron emission tomography (PET) of regional cerebral blood flow (rCBF) and subsequent statistical parameter mapping. Subjects had to respond to a row of numbers presented on tape. In one condition they had to repeat each number. In the other condition the last heard number had to be added to the number presented before. Cerebral activity specifically related to the serial addition task was distributed over supplementary motor area (SMA), left premotor cortex and superior dorsal parietal cortex bilaterally, without significant involvement of prefrontal cortex. This indicated circuitry related to mental performance characterised by a fixed strategy of executing serial manipulation of numbers within “internal space”. The main aim of this communication is to discuss the similarity between circuitry underlying higher order motor control and pure cognitive performance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00228634
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Potential radiopharmaceuticals for the detection of ocular melanoma (1988)
    Springer
    European journal of nuclear medicine 14 (1988), S. 382-387 
    Details
    ISSN: 1619-7089
    Keywords: 11C-DOPA ; 11C-tyrosine ; Melanoma ; Positron emission tomography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In order to investigate the possibility of using [1-11C] labelled 3,4-dihydroxyphenylalanine (DOPA) and tyrosine as radiopharmaceuticals for the detection of eye melanoma, the biodistributions of the same 1- and 3-14C-labelled compounds were investigated in Syrian golden hamsters with Greene melanoma. The results of these investigations were compared with positron emission tomography (PET) images of 11C labelled DOPA and tyrosine. The synthesis of these 11C labelled compounds procures of DL mixture, from which D and L forms can be separated. One h after intravenous injection, both 14C labelled DL-, L-and D-DOPA showed a high uptake in tumour tissue, that of DL- and D-DOPA being the highest. These high uptakes, together with relatively low uptake in bone, skin and eye resulted in high tumour/non tumour ratio (for DL-DOPA 5.9, 4.5 and 6.6 respectively). Extraction of the tumour tissue with trichloroacetic acid showed that L-DOPA was mainly incorporated into melanin, whereas D-DOPA was not. Also, the uptake 1 h after intravenous injection of 1-14C-L- and DL-tyrosine into the tumour were high, but L- and DL- were less different; tumour/non tumour ratios were favorable. PET images of the tumour obtained 40–80 min after injection of the [1-11C] labelled DOPA and tyrosine confirmed that melanoma detection was promising and that D-DOPA produced a better melanoma image than L-DOPA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00254389
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