'Objective' algorithm for maximum frequency estimation in Doppler spectral analysers

Abstract

Real-time spectral analysis is often used to detect the maximum frequency envelope of Doppler signals, and thus the so-called spectral broadening, which is claimed to be a sensitive indicator of arterial stenosis. However, a rational criterion for the estimation of maximum frequencies is lacking. In the paper an 'objective' algorithm which takes account of the specificity and the sensitivity of the procedure of maximum frequency detection is proposed. This algorithm is based on the statistical characteristics of FFT spectral estimators, and allows thresholds to be set to be used in two-step decision procedures. The proposed algorithm can be easily implemented on microcomputers and/or commercial spectral analysers. The results obtained are fairly independent of the operator's subjective judgement and spectral analyser gain. © 1985 IFMBE.