The sonographic stenosis index: computer simulation of a novel method for detecting and quantifying arterial narrowing.

Purpose: We introduce a new technique for quantifying arterial stenoses, stenosis index (SI), using frequency analysis of the spectral Doppler waveform.

Methods: Spectral Doppler waveforms obtained distal to arterial stenoses were enveloped, and the envelope was transformed into the frequency domain via Fourier transform. Stenosis index represents the ratio of the power in high-frequency harmonics to the power in the fundamental frequency.