Spectral Doppler enables the Doppler frequency shift within a pre-selected region-of-interest to be displayed as a function of time. Most accurate measurements are made when the Doppler scatterers are moving in the direction of the transmitted ultrasound beam. If the ultrasound beam cannot be aligned with the direction of blood flow, an angle correction can be made which attempts to compensate for this lack of alignment . Due to the rapid generation of ultrasound images, all scanners have the capability to freeze image acquisition and scroll through a pre-defined number of images in order to review the most recent acquisitions. Single images and short video clips can be saved on the scanner—the length of video clip is usually pre-set and tends to be longer for video clips acquired during echocardiographic studies and contrast imaging studies than for abdominal scans .
For injections into joints, this has recently been shown to … Read MoreRead More »