The estimation accuracy for ultrasonic Doppler velocity distribution of arterial blood flow based on coherent plane wave compounding

Abstract

The velocity distribution of arterial blood flow is an important parameter to evaluate the physiological and pathological conditions of human body. In the ultrasonic detection, the traditional focus mode has low frame rate in linear scan, poor detected accuracy outside the focus points, difficulty of quick estimation in two-dimensional area and some other limitations, is restrainedly used in clinic. Plane wave doesn't make beam forming in emission, so the frame rate can reach 20 kHz. It can obtain the two-dimensional velocity distribution covered by the transducer at one emission and reception. And the detected region that is penetrated by coherent plane wave compound with different inclination angle is helpful to improve the estimated accuracy of blood flow velocity distribution (BFVD). However, the key factors, inclination angle interval and compound times, are lack of systematic investigation in terms of the estimated accuracy of BFVD. In present study, an intensive research on this issue based on Field II platform is made. Plane wave imaging mode, coherent plane wave compound, autocorrelation estimation and other methods are used to deal with pulse-echo radio frequency signals to calculate the BFVD. In the simulation experiment, transducer emits plane waves of different inclination angle, then, the velocity is estimated respectively from the signals combined coherently by 3, 5, 7 and 9 times. The results show that the normalized root mean square errors (NRMSE) are 0.24, 0.30, 0.35 and 0.36 when the inclination angle is set to ± 0.5°, ± 7°, ± 14° and ± 21° at the compound times of 3. The accuracy of the estimated results has an opposite trend with the increase of inclination angle interval. It also shows that the NRMSE are 0.24, 0.23, 0.22 and 0.22 when using 3, 5, 7 and 9 times to compound at a fixed angle interval of ± 0.5°. The accuracy of the estimation results is related slightly to the number of compound.