Sökning: "power Doppler"
Visar resultat 1 - 5 av 61 avhandlingar innehållade orden power Doppler.
Sammanfattning : The purpose of this work was to: a) Determine whether the amount of colour in a power Doppler image is dependent on the angle between the examined vessel and the soundbeam and/or on the velocity of the flow within the vessel; b) Investigate if a dependency on flow velocity could be used for the detection of volume flow differences and c) Define clinical applications utilising the improved sensitivity to low flow of PD.In the experimental studies (study I and II) a silicon tube in a water bath was insonated, the insonation angle and the volume flow changed and the resulting images stored, transferred to a personal computer and analysed with regard to the amount of colour present in the image. LÄS MER
Sammanfattning : Power Doppler ultrasound (PDU) is a sensitive technique to detect slow blood movement. The aim of the present study was to develop a standardized method for quantification of the PDU signals recorded from a specific region of interest (ROI) within fetal organs. LÄS MER
Sammanfattning : Over the last decade a number of emerging technologies have become available for the non-invasive study of skin anatomy and physiology. In this thesis, a method for mapping tissue perfusion based on the laser Doppler technique is presented together with some of the associated experimental and clinical applications. LÄS MER
Sammanfattning : Laser Doppler flowmetry (LDF) is virtually the only non-invasive technique, except for other laser speckle based techniques, that enables estimation of the microcirculatory blood flow. The technique was introduced into the field of biomedical engineering in the 1970s, and a rapid evolvement followed during the 1980s with fiber based systems and improved signal analysis. LÄS MER
Sammanfattning : A laser Doppler flowmeter for non-invasive microcirculatory blood flow studies has been developed. The tissue under study is illuminated by laser light (helium-neon laser, output power 2 mW) via an optical fibre and the Doppler shift oflight scattered in moving red cells is analysed. LÄS MER