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  • 1
    ISSN: 1432-1084
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. A novel ultrasonic imaging method, wideband harmonic imaging, for nonlinear imaging of microbubble contrast agents is evaluated. In wideband harmonic mode, two pulses of alternate phase are send out. The image is then processed from the sum of both pulses, resulting in an image of nonlinear scatterers such as microbubbles. A prototype ultrasound system, Siemens Elegra, was evaluated with in vitro investigations and animal trials, using conventional, harmonic and wideband harmonic settings with the galactose based ultrasound contrast agent Levovist. Wideband harmonic imaging offers superior sensitivity for ultrasound contrast agents compared to conventional imaging and harmonic imaging. At low transmit power settings (MI 0.1–0.5) the nonlinear response is already sufficient to generate a image of the blood pool distribution of Levovist in the rabbit kidney including the microvasculature, with clear delineation of vessels and perfused parenchyma. At high transmit amplitudes, nonlinear tissue response reduced the apparent image contrast between contrast agent and tissue. The results suggest that wideband harmonic imaging is currently the most sensitive contrast imaging technique, maintaining highest spatial resolution. This may add to image quality and offer new clinical potential for the use of ultrasound contrast agents such as Levovist.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1084
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. The purpose of this study was to evaluate the imaging properties and diagnostic potential of the novel polymeric ultrasound contrast agent SHU 563 A. After i. v. injection, the agent circulates in the blood pool for about 10 min and is then subsequently sequestered by the RES cells predominantly in the liver. The acoustic emission capabilities enable a very sensitive detection during the blood pool phase and after uptake in the RES cells, contributing to differential diagnosis as well as detection of liver lesions. During a multicenter study, 28 patients with liver lesions were examined. In all patients the results were compared to baseline ultrasound and Contrast enhanced Spiral CT. With respect to lesion size and location, very good agreement between SHU 563 A ultrasound and Spiral CT was achieved. Additional lesions could be shown in the RES phase by SHU 563 A enhanced ultrasound. 26 further patients were examined in other indications. The results in all 54 patients indicate good safety and tolerance of SHU 563 without limitations for diagnostic use. SHU 563 A enhanced ultrasound adds significantly to the detection and delineation of focal liver lesions by improving conspicuity due to RES based contrast after uptake.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Solid State Electronics 21 (1978), S. 1445-1450 
    ISSN: 0038-1101
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Surgical endoscopy and other interventional techniques 4 (1990), S. 114-117 
    ISSN: 1432-2218
    Keywords: Rat liver model ; Intraoperative echo contrast sonography ; Hepatomas ; Echo contrast medium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The present animal experimental study showed that intraoperative hepatic ultrasonography using an echo contrast medium can visualize small hepatomas (with a diameter of between 3 and 15 mm) induced in the rat liver, although they were not recognizable with plain ultrasonography. A homogeneous increase in the echogenicity of the liver tissue was achieved by using an echo contrast medium (Echovist) based on galactose microparticles. Selfmade bubble preparations such as those used in echocardiography were far less effective. When the dosage was optimal (0.01−0.003 ml/g liver weight with concentrations of 200 and 300 mg/ml Echovist), homogeneous contrast enhancement of the liver was achieved for at least 10 min after a single bolus injection via all routes of contrast adminstration (hepatic artery, portal vein, bile duct). As a result, hepatomas appeared as hypodense formations (portal vein and bile duct) or as hyperdense zones (hepatic artery).
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Archives of gynecology and obstetrics 245 (1989), S. 443-445 
    ISSN: 1432-0711
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Der Radiologe 36 (1996), S. 51-57 
    ISSN: 1432-2102
    Keywords: Schlüsselwörter Ultraschall ; Doppler ; Kontrastmittel ; Key words Ultrasound-Doppler-Contrast agent ; Signal enhancement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Ultrasound contrast agents have recently proven to be clinically useful in many different areas and with many different ultrasound modalities. B-mode contrast echocardiography and delineation of cavities with ultrasound contrast agents are already accepted. Based on the contrast agent Echovist, assessment of tubal patency is possible with hysterosalpingo contrast sonography (HyCoSy). A new generation of transpulmonary, stable ultrasound contrast agents such as Levovist offer potential for various Doppler applications. Ultrasound contrast agents act as signal enhancers in Doppler examinations and therefore help to overcome the limitations of insufficient Doppler signal intensity. Recently, clinical studies have shown. Doppler examinations to have many clinical benefits. Contrast agents are useful in the assessment of high-grade stenosis or the delineation of small vessels and under difficult conditions. Ultrasound contrast agents also create new applications: analysis of tumor vascularization and delineation of the transcranial venous system are possible with contrast enhancement. Future developments in contrast-specific scanning (“harmonic imaging”) and new contrast agents, including organ-specific contrast agents, are expected to make a significant impact in the years to come.
    Notes: Zusammenfassung Ultraschallkontrastmittel stehen an der Schwelle zur klinischen Routineanwendung mit nahezu allen Ultraschallverfahren in vielfältigen klinischen Einsatzgebieten. Bereits am weitesten fortgeschritten sind B-Mode-Anwendungen wie Kontrastechokardiographie und die Darstellung von Hohlräumen mit Ultraschallkontrastmitteln. So wurde mit der auf dem ersten Echokontrastmittel Echovist® basierenden Hysterosalpingokontrastsonographie (HyCoSy) eine Alternativmethode zur Röntgen-HSG bzw. laparaskopischen Verfahren zur Darstellung der Eileiterdurchgängigkeit geschaffen. Durch neue lungenpassagestabile Ultraschallkontrastmittel wie Levovist® eröffnen sich viele Anwendungsgebiete mit Ultraschalldopplertechniken. Klinische Studien belegen, daß die Echosignalverstärkung durch Ultraschallkontrastmittel für eine Befundung unzureichende Dopplersignale darstellbar macht und so die Anwendbarkeit der Doppleruntersuchungen erweitert. Praktische klinische Vorteile sind so z. B. bei schwierigen Untersuchungsbedingungen, bei der Bewertung hochgradiger Stenosen, und bei der Darstellung kleiner Gefäße zu erzielen. Auch werden durch den Einsatz von Levovist® neue Anwendungen wie transkranielle Venendarstellung und Bewertung von Tumorvaskularisation ermöglicht. Zukünftige kontrastmittelspezifische Scanverfahren („harmonic imaging“) sowie neuartige, z. T. organspezifische Echokontrastmittel lassen eine Reihe von weiteren Innovationen erwarten.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Der Radiologe 38 (1998), S. 394-398 
    ISSN: 1432-2102
    Keywords: Schlüsselwörter Dreidimensionale Bildgebung ; Ultraschallkontrastmittel ; Transkranielle Duplexsonographie ; Power-Doppler ; Hirntumoren ; Key words Three-dimensional imaging ; Ultrasound contrast agents ; Transcranial duplex sonography ; Power Doppler ; Brain tumors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Echo-enhancing agents improve the signal intensity of transcranial Doppler signals, enabling a novel approach of three-dimensional transcranial vascular imaging by Doppler ultrasound. The basic principle, system requirements and early clinical results with a custom built system are described. Transcranial color Doppler imaging was performed through the temporal bone acoustic window. During IV administration of the transpulmonary stable, galactose-based echoenhancer Levovist® (Schering) the video output of the ultrasound scanner was digitized and the spatial position of the recorded frames was simultaneously registered using a mechanical position sensor. After automatic segmentation of the color information, the 3D datasets were reconstructed offline using a Unix-based workstation (Silicon Graphics). Visualization was achieved by maximum intensity projection or surface visualization techniques. Administration of Levovist® resulted in good enhancement of the vascular Doppler signal intensity, enabling acquisition of a 3D dataset of the complete circle of Willis with an imaging window of approximately 3–5 min for one IV injection. The vascularity of tumors could be recorded as a 3D dataset and further analyzed. The power Doppler technique with echoenhancement proved a valuable tool for 3D dataset recording. 3D datasets clearly facilitated the diagnosis of the vascular anatomy and lesion vascularity and provided additional information on localization of feeders, vascular displacement and extent of tumor vascularity.
    Notes: Zusammenfassung Echosignalverstärker verbessern die Signalintensität des transkraniellen Dopplersignals und ermöglichen damit die dreidimensionale Darstellung mittels transkraniellem Doppler-Ultraschall. Die grundlegenden Prinzipien, Systemvoraussetzungen und erste klinische Ergebnisse werden berichtet. Transkranielle Bildgebung erfolgte mit einem konventionellen Farbdopplersystem durch die intakte Schädelkalotte des Os temporale. Das Videosignal des Ultraschallgerätes wurde während der i.v. Applikation des galaktosebasierenden Echosignalverstärkers Levovist® (Schering) digitalisiert und die Position des jeweiligen Bildes mit einem mechanischen Sensorsystem erfaßt. Die Farbinformation wurde automatisch segmentiert und ein dreidimensionaler Datensatz daraus rekonstruiert, der auf einer Unix Workstation (Silicon Graphics) mittels Maximum-intensity-Projektion oder Oberflächendarstellung visualisiert wurde. Die Anwendung von Levovist® zeigte eine gute Signalverstärkung in einem Zeitraum von 3–5 min für eine i.v. Injektion, der eine Erfassung eines 3D-Datensatzes des kompletten Circulus Willisii bei allen Patienten ermöglichte. Zusätzlich konnte die Vaskularisation von Tumoren bei einigen Patienten dargestellt und weiter analysiert werden. Die angewandte Power-Doppler-Technik bildete zusammen mit Echosignalverstärkung die Basis für die Aufnahme bestmöglicher 3D-Datensätze. Die 3D-Visualisierung erleichterte die Darstellung komplexer Gefäßverläufe und zeigte zuführende Gefäße, Gefäßverlegungen und hochvaskularisierte Bereiche in Tumoren auf.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1573-0743
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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