A STUDY OF THE SPECTRAL BROADENING OF SIMULATED DOPPLER SIGNALS USINGFFT AND AR MODELING

Doppler ultrasound is used clinically to detect stenosis in the caroti d artery, The presence of stenosis may be identified by disturbed flow patterns distal to the stenosis that cause spectral broadening in the spectrum of the Doppler signal around peak systole, This paper invest igates the behaviour of the spectral broadening index (SBI) derived fr om wide-band spectra obtained using autoregressive modelling (AR), com pared with the SBI based on the fast-Fourier transform (FFT) spectra, Simulated Doppler signals were created using white noise and shaped fi lters to analyse spectra typically found around the systolic peak and to assess the magnitude and variance of AIR and FFT-SBI for a range of signal-to-noise ratios. The results of the analysis show a strong cor relation between the indices calculated using the FFT and AR algorithm s, Despite the qualitative improvement of the AR spectra over the FFT, the estimation of SBI for short data frames is not significantly impr oved using AR, (C) 1997 World Federation for Ultrasound in Medicine & Biology.