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  • Digitale Medien  (3)
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  • Digitale Medien  (3)
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  • 1
    Digitale Medien
    Digitale Medien
    Fourier and factorial analysis: An objective and comparative evaluation on a cardiac phantom (1987)
    Springer
    European journal of nuclear medicine 13 (1987), S. 450-455 
    Details
    ISSN: 1619-7089
    Schlagwort(e): Fourier analysis ; Orthogonal factor analysis ; Factor analysis of dynamic structures ; Cardiac phantom
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Orthogonal and oblique factor analysis represent an alternative to Fourier analysis in the evaluation of cardiac dynamic behaviour in gated blood pool studies. In order to estimate their respective places, orthogonal factor analysis (OFA), factor analysis of dynamic structures (FADS) and Fourier analysis (FA) are tested on a dynamic and periodical phantom with well known and reproducible kinetics. The phantom data are acquired under standard conditions by varying the counting rates and the temporal frequency sampling. To compare the results of the three methods with maximal objectivity, the relative contribution of each component is calculated. With standard acquisition conditions, FA and OFA give very close results. Only a minor advantage in evaluation of small phase differences is observed with OFA. FADS solutions are effectively related to the dynamic behaviour of the phantom, but their interpretation is more complicated and the quality of the oblique factors is reduced as the number of calculated factors increases. The influence of the counting statistics on FA, OFA and FADS is very similar. However, in cases of undersampling, robustness is demonstrated with the factorial technics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00281859
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Thyrotropin-releasing hormone radioimmunoassay in human serum and its application in thyroidal pathology (1981)
    Springer
    European journal of nuclear medicine 6 (1981), S. 73-78 
    Details
    ISSN: 1619-7089
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract This paper presents the methodology of a specific radioimmunoassay of the Thyrotropin-Releasing Hormone (TRH) and the results obtained in patients with thyroid disorders. Synthetic TRH was labeled by iodine 125 at room temperature using a technique with Chloramine-T. The labeled compound was purified on a column chromatograph, and it was found the immunoreactivity of labeled-TRH was dependent on the elution fraction. Anti-TRH antibodies were obtained in rabbits after coupling the molecule with albumin using a diazotization method. Good antibody titers were obtained within 45 days. Blood samples were collected on a EDTA-8 hydroxyquinoline sulfate-Tween 20 mixture and kept at 4° C. TRH was extracted from the serum by methanol precipitation and 60° C evaporation. The assay methodology included incubation at 4° C for 48 h, and separation of free and bound fractions was achieved by immunoprecipitation with antirabbit goat antiglobulins. This methodology gave a very high specificity and the range was from 10 to 2,000 pg/ml with an Ekins sensitivity of 20 pg/ml. In 62 normal patients, plasma TRH mean value and SD were found to be 137±53 pg/ml. The clinical results show a significant decrease of TRH levels in hyperthyroid patients (Graves' disease and multinodular toxic goiter), and and increase in the few hypothyroid subjects examined, arguing strongly for the negative feed-back hypothesis. However, TRH levels were found to be increased in cold nodules (although with euthyroid function) and in the normal range in Plummers' disease, stating the problem of its pathogeny. Thus, we think that this TRH radioimmunoassay is very suitable and appropriate for routine use in human patients with thyroidal disorders. In the future it should be used as a dynamic test for the investigation of the kinetics of the hypothalamic TRH release.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00253717
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Emission computerized axial tomography from multiple gamma-camera views using frequency filtering (1980)
    Springer
    European journal of nuclear medicine 5 (1980), S. 1-5 
    Details
    ISSN: 1619-7089
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Emission computerized axial tomography is achievable in any nuclear medicine department from multiple gamma camera views. Data are collected by rotating the patient in front of the camera. A simple fast algorithm is implemented, known as the convolution technique: first the projection data are Fourier transformed and then an original filter designed for optimizing resolution and noise suppression is applied; finally the inverse transform of the latter operation is back-projected. This program, which can also take into account the attenuation for single photon events, was executed with good results on phantoms and patients. We think that it can be easily implemented for specific diagnostic problems.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00261198
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