HIGH-RESOLUTION ULTRASONIC BACKSCATTER COEFFICIENT ESTIMATION BASED ON AUTOREGRESSIVE SPECTRAL ESTIMATION USING BURG ALGORITHM

An autoregressive (AR) method for spectral estimation was applied towa rd the task of estimating ultrasonic backscatter coefficients from sma ll volumes of tissue. High spatial resolution is desirable for generat ing images of backscatter coefficient. Data was acquired from a homoge neous tissue-mimicking phantom and from a normal human liver in vivo. The AR method was much more resistant to gating artifacts than the tra ditional DET (discrete Fourier Transform) approach. The DFT method con sistently underestimated backscatter coefficients at small gate length s. Therefore backscatter coefficient image formation will be quantitat ively more meaningful if based on AR spectral estimation rather than t he DFT. The autoregressive method offers promise for enhanced spatial resolution and accuracy in ultrasonic tissue characterization and nond estructive evaluation of materials.