. "Doppler ultrasonography" . "Doppler effect" . "Doppler ultrasound" . "doppler ultrasonography" . . "Doppler" . . "Vascular ultrasonography" . "blood flow" . . . "Ultrasonic duplex scanning" . . . "2\u2010dimensional color Doppler imaging" . "ultrasound transducer" . "Doppler unit" . "ultrasound with doppler" . "ultrasonic duplex testing" . "Doppler techniques" . "Doppler mode" . "Doppler examination" . . . "Doppler ultrasonography" . "Doppler ultrasonography combined with duplex ultrasonography" . . . "venous duplex ultrasonography" . "Doppler ultra sound techniques" . . "color duplex scanning" . "Doppler transducer" . "doppler" .