A new time-domain narrowband velocity estimation technique forDoppler ultrasound flow imaging. II. Comparative performance assessment

摘要

For pt.I see ibid., vol.45, no.4, pp.939-54 (1998). Thenstatistical performance of the new 2-D narrowband time-domain root-MUSICnblood velocity estimator described previously is evaluated using bothnsimulated and flow phantom wideband (50% fractional bandwidth)nultrasonic data. Comparisons are made with the standard 1-D Kasainestimator and two other wideband strategies: the time domain correlatornand the wideband point maximum likelihood estimator. A special case ofnthe root-MUSIC, the “spatial” Kasai, is also considered.nSimulation and flow phantom results indicate that the root-MUSIC bloodnvelocity estimator displays a superior ability to reconstruct spatialnblood velocity information under a wide range of operating conditions.nThe root-MUSIC mode velocity estimator can be extended to effectivelynremove the clutter component from the sample volume data. A bimodalnvelocity estimator is formed by processing the signal subspace spannednby the eigenvectors corresponding to the two largest eigenvalues of thenDoppler correlation matrix. To test this scheme, in vivo common carotidnflow complex Doppler data was obtained from a commercially availablencolor flow imaging system. Velocity estimates were made using a reducednform of this data corresponding to higher frame rates. The extendednroot-MUSIC approach was found to produce superior results when comparednto both 1- and 2-D Kasai-type estimators that used initialized clutternfilters. The results obtained using simulated, flow phantom, and in vivondata suggest that increased sensitivity as well as effective clutternsuppression can be achieved using the root-MUSIC technique, and this maynbe particularly important for wideband high frame rate imagingnapplications