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  • Biopsy  (2)
  • 73  (1)
  • 74.70  (1)
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 44 (1987), S. 75-79 
    ISSN: 1432-0630
    Schlagwort(e): 74.00 ; 74.10 ; 74.70 ; 79.60
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract XPS and UPS photoemission results on the new high-T c oxide superconductors La2−xMexCuO4 (Me=Sr, Ba) with a maximumT c≈40 K show the following: 1) the electronic density of states atE F is small (smaller than in pure Cu); the work function is metallic like with a value around 4.2 eV. 2) The Cu-2p spectra show hardly a possible small tendency to a mixed valent Cu3+/Cu2+state with increasing Me content, but smaller than expected from the Me2+ concentration suggesting that oxygen defects are responsible for the charge compensation. 3) The core level spectra of La, Me, and O show satellites which are at least partially related to O2− defects and which change in intensity with increasing surface sensitivity of the experiments. First core-level spectra on y1.2Ba0.8CuO4 with aT c ≈ K indicate a complicated composition of these new compounds.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 21 (1980), S. 345-352 
    ISSN: 1432-0630
    Schlagwort(e): 71.20 ; 71.55 ; 73
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract The electronic properties of Ar-ion and electron bombarded single-crystal surfaces of LiNbO3 have been investigated at room temperature by ultraviolet photoelectron spectroscopy (UPS) and x-ray excited photoelectron spectroscopy (XPS). In crystals reduced in this way, the loss of oxygen is accompanied with a loss of lithium and the creation of Nb4+ and Nb3+ ions. The relative concentrations of the various defects have been determined from their corresponding XPS core line spectra. When surface defects are produced an emission in the region of the bulk band gap appears. This gap emission is identified as arising from Nb 4d electrons due to the reduction of Nb5+ ions to Nb4+ and Nb3+ ions. The different behaviour of the gap emission upon surface treatment in the UPS and the XPS spectra is discussed.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    ISSN: 1432-1084
    Schlagwort(e): Key words: Thyroid ; Biopsy ; Interventional MR ; MR guidance ; Stereotaxis ; Ultrasound
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract. The aim of this study was to demonstrate the clinical feasibility and utility of an interactive MR-guidance system to target and biopsy thyroid lesions, and to compare resolution between ultrasound and interventional MR imaging in the evaluation of thyroid lesions. Twenty thyroid lesions of 18 patients were interactively biopsied using a 0.5-T superconducting open magnet system. Stereotactic localization of the needle and imaging was accomplished using T1-weighted gradient-recalled-echo (GRE) images. Representative cytological material was retrieved in 16 of 20 lesions (benign cystic or colloid goiter: n = 14; one de Quervain's thyroiditis and one follicular neoplasia). Lesions smaller than 1.5 cm detected by ultrasound could not be visualized adequately on GRE images. Lesions smaller than 1.5 cm were successfully biopsied by ultrasound (three colloid and haemorrhagic goiters and one adenoma). Magnetic-resonance-guided interactive biopsies and positioning of non-ferromagnetic needles in the thyroid gland are technically feasible and safe. Compared with high-resolution ultrasound, lesions larger than 1.5 cm can be adequately visualized and biopsied. Magnetic-resonance-guided placement of non-ferromagnetic needles is no substitute for high-resolution ultrasound in clinical work-up of thyroid lesions.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    ISSN: 1432-2102
    Schlagwort(e): Schlüsselwörter Endometriose ; Biopsie ; Nadel ; Magnetresonanztomographie ; Interventionelle Radiologie ; Key words Endometriosis ; Biopsy ; needle ; Magnetic resonance imaging ; Interventional radiology
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Summary Introduction and Methods: A 0.5 T open-configuration MR system allows free access to the patient via a 58-cm-wide opening on both sides of the machine. A newly developed system for needle guidance enables the examiner to perform biopsies in combination with real-time imaging and to position laser fibers in the human body. For imaging, a 2D gradient echo sequence is used (TR 19 ms, TE 9 ms, flip angle 30 °, FOV 24 × 24 cm, slice thickness 10 mm matrix 256 × 128). The acquired images are displayed on two LCD screens localized within the MR system, thus allowing an interactive needle guidance. This procedure is illustrated by a case report. Discussion: The handling of the system for needle guidance was simple, mainly due to a real-time adaption of the scan plane to the needle direction. The possibility of multi-angulated approaches makes biopsies of hardly accessible anatomic regions feasible. Conclusion: We think that MR-guided needle positioning will play an important role in combination with thermosensitive therapies. Thermosensitivity of MR imaging allows extensive monitoring of such interventions.
    Notizen: Zusammenfassung Ein offenes, interventionelles MR-Gerät (0,5 Tesla) erlaubt durch eine 58 cm breite Öffnung den Zugang zum im Gerät liegenden Patienten. Ein spezielles Punktionssystem ermöglicht es, unter Echtzeitbildgebung Punktionen vorzunehmen sowie auch Laserfasern im menschlichen Körper zu plazieren. Zur Bildgebung wird eine 2d-Gradientenechosequenz verwendet (TR 19 ms, TE 9 ms, Flipwinkel 30 °, FOV 24 × 24 cm, Schichtdicke 10 mm, Matrix 256 × 128). Die akquirierten Bilder werden dem punktierenden Radiologen auf 2 im Gerät angebrachten LCD-Monitoren angezeigt, wodurch eine interaktive Nadelführung ermöglicht wird. Es wurden bereits zahlreiche Punktionen an Patienten durchgeführt. Wichtig wird die MR-gesteuerte Punktion von Läsionen in Kombination mit der Durchführung thermosensitiver Therapien. Die der MR-Bildgebung inhärente Temperatursensitivität ermöglicht ein umfassendes Monitoring solcher Eingriffe in Echtzeit.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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