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Sökning: WFRF:(Olsson Bengt) > (2000-2004) > Ask Per 1950

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  • Walker, Andrew, et al. (författare)
  • Accuracy of spectral Doppler flow and tissue velocity measurements in ultrasound systems
  • 2004
  • Ingår i: Ultrasound in Medicine and Biology. - : Elsevier BV. - 0301-5629 .- 1879-291X. ; 30:1, s. 127-132
  • Tidskriftsartikel (refereegranskat)abstract
    • Blood and tissue velocity are measured and analysed in cardiac, vascular and other applications of diagnostic ultrasound (US). An error in system calibration is a potential risk for misinterpretation of the measurements. To determine the accuracy in velocity calibration, we tested three common commercial US systems using a Doppler string phantom. We tested pulsed and continuous-wave Doppler modes for velocities relevant to both cardiac blood flow and tissue-velocity estimation. The US systems were tested with settings and transducers commonly used in cardiac applications. One system consistently overestimated velocity by about 5%, whereas the other two systems were quite accurate in velocity estimation. These findings emphasize the importance of continuous quality control of US equipment.
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3.
  • Walker, Andrew, et al. (författare)
  • Time delays in ultrasound systems can result in fallacious measurements.
  • 2002
  • Ingår i: Ultrasound in Medicine and Biology. - 0301-5629 .- 1879-291X. ; 28, s. 259-263
  • Tidskriftsartikel (refereegranskat)abstract
    • Even short time delays (less than 30 ms) in cardiac motion pattern may have clinical relevance. These delays can be measured with echocardiography, using techniques such as flow and tissue Doppler and M-mode together with external signals (e.g., ECG and phonocardiography). If one or more of these signals are delayed in relation to the other signals (asynchronous), an incorrect definition of cardiac time intervals can occur, the consequence of which is invalid measurement. To determine if this time delay in signal processing is a problem, we tested three common ultrasound (US) systems using the ECG as the reference signal. We used a digital ECG simulator and a Doppler string phantom to obtain test signals for flow and tissue pulsed Doppler, M-mode, phonocardiography, auxiliary and ECG signals. We found long time delays of up to 90 ms in one system, whereas delays were mostly short in the two other systems. The time delays varied relative to system settings. Consequently, to avoid these errors, precise knowledge of the characteristics of the system being used is essential. Federation for Ultrasound in Medicine & Biology.
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