Doppler ultrasound signal spectral response in the measurement of the blood flow turbulence caused by stenosis

This research work is concerned to the use of a Doppler ultrasound system aiming to study the effect caused in the blood flow by stenotic lesions. In order to accomplish this study, an experimental blood flow phantom was constructed. This is a controlled platform that allows to generate a range of blood flow profiles, and also to produce different degree of stenosis on a testing vessel. The phantom has also been electrically modeled in order to asses the response under conditions both normal and pathological (with stenosis). The flow average velocity is estimated by calculating the Pseudo Instantaneous Mean Frequency (PIMF) of a discrete Doppler ultrasound signal produced with a blood flow phantom. This signal is conditioned, digitized and processed in order to generate a 2-D spectrogram to be displayed and for calculating suitable clinical parameters like flow, pulsatile index and resistance index, among others. A graphical user interface (GUI) has been developed for input, output and set control variables and monitoring the system. The results in this study demonstrate a suitable use of Doppler ultrasound spectral analysis of blood flow in order to evaluate the degree of stenosis in vessels.