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  • 1
    ISSN: 1619-7089
    Keywords: Single-photon emission tomography ; Ethyl cysteinate dimer ; Hexamethylpropylene amine oxime ; Regional cerebral blood flow ; Quantitation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This report describes a comparative study between technetium-99m ethyl cysteinate dimer (ECD) and 99mTc-hexamethylpropylene amine oxime (HMPAO) in five neurological patients. The conversion kinetics of the tracers in the blood from forms capable of diffusion across the blood-brain barrier to non-diffusible forms were studied by arterial sampling and rapid octanol extraction. We observed that HMPAO has a faster conversion rate in the blood but that the fraction of the injected dose available for brain extraction is higher than in the case of ECD. Regional brain concentrations of the tracers were measured with single-photon emission tomography (SPET) 35 min and 60 min after the injection and remained stable within this interval. On the basis of the measurements of the arterial input and of SPET brain concentrations of the tracers, the regional steadystate influx constants (Ki in ml/min/g) were determined for several brain regions. In the grey matter the Ki values were (mean ± SD) 0.32 ± 0.03 and 0.35 ± 0.04 for HMPAO and ECD, respectively; in the white matter the values were 0.23 ± 0.01 and 0.23 ± 0.02, respectively. The Ki values of the two tracers in corresponding regions were closely correlated (P〈0.001). The correspondence of the Ki values of ECD and HMPAO demonstrates that ECD can also be considered a tracer that may be used for quantitative measurements of brain perfusion.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1619-7089
    Keywords: Key words: Behçet’s disease ; Tomography ; emission computed ; Acetazolamide ; Diaschisis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. The purpose of this study was to characterise the nature of the baseline perfusion defects found in patients with Behçet’s disease using hexamethylpropylene amine oxime single-photon emission tomography in conjunction with acetazolamide test (Acz SPET). Eleven patients underwent both baseline and Acz SPET. Regions of interest (ROIs) were drawn on the areas with decreased perfusion (D-ROI) and, in the same section, on areas with normal perfusion (N-ROI). The ROIs were then repositioned on the corresponding section on Acz SPET. The mean ROI counts were then transformed into a perfusion index value (PIV) with reference to the global brain counts. In total we found 24 D-ROIs (17 in the cortical and 7 in subcortical grey matter). The influence of Acz infusion was selectively registered in the D-ROIs, where PIVs changed from 1.23±0.17 (baseline SPET) to 1.63±0.23 (Acz SPET) (P〈0.001). No significant difference was seen in the N-ROIs (1.46±0.21 and 1.40±0.17, respectively, on baseline SPET and Acz SPET). Our results demonstrate that Acz infusion increases the regional cerebral blood flow within baseline grey matter perfusion defects. This finding suggests that baseline perfusion abnormalities could reflect a disconnection rather than local vasculitic involvement.
    Type of Medium: Electronic Resource
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