INSPECTION OF STENOSIS AND OCCLUSION IN ARTERIES WITH AR METHOD USING MAXIMUM LIKELIHOOD ESTIMATION
Doppler ultrasound is used in the inspection of the velocity, direction, and volume of blood flow. Therefore, Doppler ultrasonography is known as a reliable technique, which demonstrates the flow characteristics and resistance of arteries in various vascular diseases. In this study, spectral analysis of arterial Doppler signals obtained from 105 subjects were performed by using fast Fourier transform (FFT) and autoregressive (AR) methods using maximum likelihood estimation. By using these spectrum analysis methods power spectrum densities of arterial Doppler signals were obtained. In order to obtain medical information, the variations in the shape of the Doppler power spectrum densities as a function of time were presented in the form of sonograms. These sonograms were then used to compare the spectral analysis methods in terms of their frequency resolution and the effects in determination of stenosis and occlusion in arteries. Reliable information on hemodynamic alterations in arteries were obtained by the evaluation of these sonograms.
Key words: Doppler signal, spectral analysis, power spectrum density, sonogram, stenosis, occlusion