Original contribution
Accuracy and precision of time-averaged flow as measured by nontriggered 2D phase-contrast MR angiography, a phantom evaluation

https://doi.org/10.1016/0730-725X(95)02005-EGet rights and content

Abstract

The purpose of this study was to assess the accuracy and precision of time-averaged flow as measured by nontriggered 2D PC. Mono-, bi-, and triphasic flow patterns, modelling waveforms encountered in the human vascular system, were generated by a computer-controlled flow system. Time-averaged flow velocity was measured by conventional 2D cardiac-triggered cine PC and by nontriggered 2D PC for different settings of the excitation flip angle and the velocity sensitivity. Accuracy and precision were determined by repeating the measurements (N = 6) and comparing the results against precisely known calibration values. Measurements revealed waveform-specific deviations between triggered and nontriggered acquisitions that depended on the velocity sensitivity and, more strongly, on the flip angle of the nontriggered experiment. This confirmed the theoretically predicted predominance of amplitude over phase effects. Systematic errors could be reduced by decreasing the flip angle and the velocity sensitivity, although at the expense of signal-to-noise, so that additional signal averaging was required to maintain a specified precision. The attainable accuracy appeared to be acceptable only for waveforms with a relatively low pulsatility index. The study demonstrates the feasibility of accurate and precise nontriggered velocity measurements for weakly pulsatile flow and indicates a route towards improving the reliability for highly pulsatile flow.

References (13)

  • G.L Nayler et al.

    Blood flow imaging by cine magnetic resonance

    J. Comput. Assist. Tomogr.

    (1986)
  • D Meier et al.

    Quantitative flow measurements on phantoms and on blood vessels with MR

    Magn. Reson. Med.

    (1988)
  • M.P Marks et al.

    Determination of cerebral blood flow with a phase-contrast cine MR imaging technique: Evaluation of normal subjects and patients with arteriovenous malformations

    Radiology

    (1992)
  • D.R Enzmann et al.

    Blood flow in major cerebral arteries measured by phase-contrast cine MR

    AJNR

    (1994)
  • W.L Davis et al.

    Correlation of cine MR velocity measurements in the internal carotid artery with collateral flow in the circle of Willis: Preliminary study

    J. Magn. Reson. Imaging

    (1993)
  • M Tarnawski et al.

    The measurement of time-averaged flow by magnetic resonance imaging using continuous acquisition in the carotid arteries and its comparison with Doppler ultrasound

    Clin. Phys. Physiol. Meas.

    (1990)
There are more references available in the full text version of this article.

Cited by (0)

View full text