Fundamental sources of error and spectral broadening in Doppler ultrasound signals.

Analysis of the signals, spectra and error bounds for Doppler ultrasound signals is challenging and involves numerous concepts in signal analysis, probability, acoustics, and fluid mechanics. Nonetheless, the results of this analysis must be accessible to both engineers and clinicians who work with ultrasound technology. The engineer who designs, builds, or maintains equipment must know whether specific artifacts are fundamental or can be eliminated. The clinician must be able to interpret whether specific signal features accurately represent the flow field or result from limitations of Doppler ultrasound. This article reviews recent advances in both conceptual and numerical models of the Doppler ultrasound process, and relates these advances to practical aspects such as spectral broadening, velocity estimation error, and data analysis error. It then reviews recent innovations in system implementation and signal analysis which are indicative of the future potential of Doppler ultrasound instrumentation.