Ultrasonic techniques for assessing wall vibrations in stenosed arteries

Arterial stenoses are often associated with audible bruits. Quantitative analysis of the bruit spectrum has been successfully used to predict the residual lumen diameter in carotid stenoses. Arterial wall vibrations occurring due to turbulent pressure fluctuations in the post-stenotic jet are known to be the source of the bruits. We present novel signal processing techniques that enable the detailed noninvasive assessment of these vibrations in real time using color-Doppler and pulsed-wave Doppler ultrasound. A color-Doppler-based two-dimensional vibration imaging technique can be used to locate the source of the bruits relative to the underlying anatomy. Subsequently, a pulsed-wave Doppler-based technique can be used to analyze the bruit spectrum quantitatively. Experiments in ex vivo arteries indicate that these techniques can predict the location of the bruit as well as its spectral content. Case studies on human subjects with stenosed vein grafts are presented and the clinical applicability of this technique is discussed.