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  • 1
    ISSN: 1619-7089
    Keywords: Head injury Single-photon emission tomography Nigrostriatal dysfunction Striatal dopamine transporter Striatal D2 receptor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Structural imaging suggests that traumatic brain injury (TBI) may be associated with disruption of neuronal networks, including the nigrostriatal dopaminergic pathway. However, to date deficits in pre- and/or postsynaptic dopaminergic neurotransmission have not been demonstrated in TBI using functional imaging. We therefore assessed dopaminergic function in ten TBI patients using [123I]2-β-carbomethoxy-3-β-(4-iodophenyl)tropane (β-CIT) and [123I]iodobenzamide (IBZM) single-photon emission tomography (SPET). Average Glasgow Coma Scale score (±SD) at the time of head trauma was 5.8±4.2. SPET was performed on average 141 days (SD ±92) after TBI. The SPET images were compared with structural images using cranial computerised tomography (CCT) and magnetic resonance imaging (MRI). SPET was performed with an ADAC Vertex dual-head camera. The activity ratios of striatal to cerebellar uptake were used as a semiquantitative parameter of striatal dopamine transporter (DAT) and D2 receptor (D2R) binding. Compared with age-matched controls, patients with TBI had significantly lower striatal/cerebellar β-CIT and IBZM binding ratios (P≤0.01). Overall, the DAT deficit was more marked than the D2R loss. CCT and MRI studies revealed varying cortical and subcortical lesions, with the frontal lobe being most frequently affected whereas the striatum appeared structurally normal in all but one patient. Our findings suggest that nigrostriatal dysfunction may be detected using SPET following TBI despite relative structural preservation of the striatum. Further investigations of possible clinical correlates and efficacy of dopaminergic therapy in patients with TBI seem justified.
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  • 2
    ISSN: 1619-7089
    Keywords: Dementia of the Alzheimer type ; Diffuse Lewy body disease ; Single-photon emission tomography ; Brain perfusion patterns ; Dopamine transporter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Dementia of the Alzheimer-type (DAT) is characterized by progressive cognitive decline, variably combined with frontal lobe release signs, parkinsonian symptoms and myoclonus. The features of diffuse Lewy body disease (DLBD), the second most common cause of degenerative dementia, include progressive cognitive deterioration, often associated with levodopa-responsive parkinsonism, fluctuations of cognitive and motor functions, psychotic symptoms (visual and auditory hallucinations, depression), hypersensitivity to neuroleptics and orthostatic hypotension. A recent report suggests that positron emission tomography studies in patients with degenerative dementia may be useful in the differential diagnosis of DAT and DLBD. However, the diagnostic role of single-photon emission tomography (SPET) studies remains to be established. The aim of this study was therefore to evaluate regional cerebral perfusion [with either technetium-99m hexamethylpropylene amine oxime (99mTc-HMPAO) or99mTc-ethyl cysteinate dimer (99mTc-ECD) SPET] and striatal dopamine transporter density [using iodine-123 2β-carboxymethoxy-3β-[4-iodophenyl]tropane (123I-β-CIT) SPET] in patients with DAT and DLBD. Six patients with probable DAT and seven patients with probable DLBD were studied. Blinded qualitative assessment by four independent raters of99mTc-HMPAO or99mTc-ECD SPET studies revealed bilateral temporal and/or parietal hypoperfusion in all DAT patients. There was additional frontal hypoperfusion in two patients and occipital hypoperfusion in one patient. In the DLBD group, regional cerebral perfusion had a different pattern. In addition to temporoparietal hypoperfusion there was occipital hypoperfusion resembling a horseshoe defect in six of seven patients. In the DAT group, the mean 3-h striatal/cerebellar ratio of123I-β-CIT binding was 2.5±0.4, with an increase to 5.5±1.1 18 h after tracer injection. In comparison, in the DLBD patients the mean 3-h striatal/cerebellar ratio of123I-β-CIT binding was significantly reduced to 1.7±0.3, with a modest increase to 2.1±0.4 18 h after tracer injection (P〈0.05, Scheffe test, ANOVA). These results suggest that99mTc-HMPAO or99mTc-ECD and123I-β-CIT SPET may contribute to the differential diagnosis between DAT and DLBD, showing different perfusion patterns and more severe impairment of dopamine transporter function in DLBD than in DAT.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1619-7089
    Keywords: Technetium-99m Somatostatin HYNIC Tyrosine-octreotide Scintigraphy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. [111In-diethylene triamine penta-acetic acid-d-Phe1]-octreotide (DTPA-octreotide) scintigraphy has gained widespread acceptance as a diagnostic clinical procedure in oncology for imaging somatostatin receptor-positive tumours. However, indium-111 as a radiolabel has several drawbacks, including limited availability, suboptimal gamma energy and high radiation burden to the patient. We have recently reported on the preclinical development of 99mTc-EDDA/HYNIC-TOC, a new octreotide derivative which showed promising results both in vitro and in vivo. We now report our initial clinical experiences with this new radiopharmaceutical in ten oncological patients. The clinical diagnoses were: carcinoid syndrome (n=5), thyroid cancer (n=3), pancreatic cancer (n=1) and pituitary tumour (n=1). The biodistribution and kinetics of 99mTc-EDDA/HYNIC-TOC were compared with those of 111In-DTPA-octreotide in six cases, and with those of 111In-DOTA-TOC in five cases. With the new tracer tumours were imaged within 15 min after injection and showed the highest target/non-target ratios 4 h after injection. Tumour uptake persisted up to 20 h p.i. The rate of blood clearance was similar to that of 111In-DTPA-octreotide but faster than that of 111In-DOTA-TOC, while urinary excretion was lower compared with the 111In derivatives. Semi-quantitative region of interest analysis showed that 99mTc-EDDA/HYNIC-TOC produced higher tumour/organ (target/non-target) ratios than the 111In derivatives, especially in relation to heart and muscle. Significantly more lesions could be detected in 99mTc images. We conclude that 99mTc-EDDA/HYNIC-TOC shows better imaging properties for the identification of somatostatin receptor-positive tumour sites than currently available 111In-labelled octreotide derivatives.
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  • 4
    ISSN: 1619-7089
    Keywords: Key words: Dementia of the Alzheimer type ; Diffuse Lewy body disease ; Single-photon emission tomography ; Brain perfusion patterns ; Dopamine transporter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Dementia of the Alzheimer-type (DAT) is characterized by progressive cognitive decline, variably combined with frontal lobe release signs, parkinsonian symptoms and myoclonus. The features of diffuse Lewy body disease (DLBD), the second most common cause of degenerative dementia, include progressive cognitive deterioration, often associated with levodopa-responsive parkinsonism, fluctuations of cognitive and motor functions, psychotic symptoms (visual and auditory hallucinations, depression), hypersensitivity to neuroleptics and orthostatic hypotension. A recent report suggests that positron emission tomography studies in patients with degenerative dementia may be useful in the differential diagnosis of DAT and DLBD. However, the diagnostic role of single-photon emission tomography (SPET) studies remains to be established. The aim of this study was therefore to evaluate regional cerebral perfusion [with either technetium-99m hexamethylpropylene amine oxime (99mTc-HMPAO) or 99mTc-ethyl cysteinate dimer (99mTc-ECD) SPET] and striatal dopamine transporter density [using iodine-123 2β-carboxymethoxy-3β-[4-iodophenyl]tropane (123I-β-CIT) SPET] in patients with DAT and DLBD. Six patients with probable DAT and seven patients with probable DLBD were studied. Blinded qualitative assessment by four independent raters of 99mTc-HMPAO or 99mTc-ECD SPET studies revealed bilateral temporal and/or parietal hypoperfusion in all DAT patients. There was additional frontal hypoperfusion in two patients and occipital hypoperfusion in one patient. In the DLBD group, regional cerebral perfusion had a different pattern. In addition to temporoparietal hypoperfusion there was occipital hypoperfusion resembling a horseshoe defect in six of seven patients. In the DAT group, the mean 3-h striatal/cerebellar ratio of 123I-β-CIT binding was 2.5±0.4, with an increase to 5.5±1.1 18 h after tracer injection. In comparison, in the DLBD patients the mean 3-h striatal/cerebellar ratio of 123I-β-CIT binding was significantly reduced to 1.7±0.3, with a modest increase to 2.1±0.4 18 h after tracer injection (P〈0.05, Scheffe test, ANOVA). These results suggest that 99mTc-HMPAO or 99mTc-ECD and 123I-β-CIT SPET may contribute to the differential diagnosis between DAT and DLBD, showing different perfusion patterns and more severe impairment of dopamine transporter function in DLBD than in DAT.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1619-7089
    Keywords: Key words: Gated single-photon emission tomography ; Thallium-201 ; Wall motion ; Left ventricular ejection fraction ; Stunning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Simultaneous assessment of myocardial perfusion and function by gated single-photon emission tomography (GS) after a single tracer injection provides incremental information and is feasible with technetium-99m sestamibi. The present study validated the use of GS with thallium-201 for the assessment of left ventricular ejection fraction (LVEF) and regional wall motion by comparison with two-dimensional (2D) echocardiography (echo), which has not been done before. After injection of 111 MBq 201Tl at peak bicycle exercise (n=55) or pharmacological stress (n=17), GS was acquired 15 (post stress) and 120 min post injection (rest) on a double-head camera. An automatic algorithm (QGS) was used for processing. Echo (Acuson Sequoia C256) was performed immediately after rest GS. LVEFs assessed by GS and echo were correlated. The overall and segmental sensitivity and specificity of GS for the detection of regional wall motion abnormalities (WMAs) were calculated, echo serving as the gold standard. Perfusion abnormalities were scored. The success rate of the automatic algorithm was 100%, and visually assessed image quality was good to excellent in 88% of cases. Post-stress and rest LVEF as assessed by GS were highly correlated (r=0.91). Good correlations were obtained between post-stress LVEF (GS) and rest LVEF (echo) and between rest LVEF (GS) and rest LVEF (echo) (r=0.76 and 0.86 respectively). In patients with a reduced LVEF of less than 50% (n=23), these correlations were even better (r=0.84 and 0.89 respectively). Regional wall motion abnormalities (WMAs) were identified by GS with high sensitivity and specificity (88%–100% and 82%–98% respectively) and were directly related to the extent and severity of stress as well as of resting perfusion defects. It is concluded that GS with 201Tl is a feasible and reliable tool for the evaluation of patients with compromised left ventricular function in the context of coronary artery disease, and thus improves diagnosis and prognostic stratification. Regional WMAs were identified with high diagnostic accuracy and the method may prove helpful for the detection of myocardial viability.
    Type of Medium: Electronic Resource
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