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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    European radiology 8 (1998), S. 849-857 
    ISSN: 1432-1084
    Keywords: Key words: Ultrasound ; Physics ; Vascular studies ; Vascular pathologies ; Ultrasonic contrast agents ; Clinical applications
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. The choice of the optimal ultrasonic frequency for vascular studies is determined by the required resolution and penetration. Anatomical real-time two-dimensional imaging and blood flow studies provide complementary information. Intravascular scanning allows high-frequency ultrasound to be used, with correspondingly good spatial resolution. Contrast resolution is degraded by beam side lobes and the limited dynamic range of the ultrasonic pulse. The physics of ultrasonic scattering by blood, pulsed Doppler and duplex scanning and colour flow imaging performances determines the limits of clinical applications. Contrast agents enhance the echogenicity of blood, improving sensitivity and, through second harmonic detection, suppressing solid tissue echoes. Three-dimensional display, with segmentation by the presence of the flow signal, facilitates spatial perception. Clinical applications in vascular pathologies are summarised.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    BJOG 92 (1985), S. 0 
    ISSN: 1471-0528
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Summary. The feasibility of studying ovarian arterial blood flow has been demonstrated, using an ultrasonic method combining real-time imaging and pulsed Doppler (the ‘duplex’ method). Results using a percutaneous full-bladder technique were validated by comparison with use of an ultrasound probe applied directly to the arteries at laparotomy. The ovarian arteries demonstrated qualitatively and quantitatively distinct flow patterns compared with the internal and external iliac arteries. From recorded waveforms a pulsatility index (PI) reflecting vascular impedance was calculated. The PI was found to be lower, indicating increased blood flow, in the artery supplying the ovary carrying the dominant follicle or corpus luteum. Serial studies suggest that this change occurs at an early stage of the menstrual cycle. possibly before the dominant follicle can be recognized by its size or increased hormone production. Uterine arterial flow was also detectable, more accurately abdominally than vaginally, and the changes typical of late pregnancy were already found to be present, though to a lesser degree, in the first trimester.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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