RIU 324 Lecture Notes - Lecture 22: Field Of View, Grayscale, Frame Rate
29 Mar 2020
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Prf is set by velocity scale and imaging depth i: higher velocity scale= increase prf iii. Lower prf= lower max velocity= higher velocity resolution (good for peripheral vascular work, slow flow: width and depth of fov. However, instead of displaying estimated blood velocities, power doppler is a representation of the integral under the curve of doppler-shifted frequencies returned to the transducer. That is, instead of using the frequency-shift information, power doppler uses the magnitude of all frequency-shifted echoes originating from a specified area. The color of a particular pixel represents the amount of flow energy. clinical ultrasound. Increases sensitivity to low to slow flow i: unaffected by doppler angles, no aliasing, disadvantages, no velocity or direction, lower frame rate than cdi, susceptible to motion artifact d. F. a. range ambiguity means we don"t know where the flow (or doppler shifts) came from. Shadowing of enhancement artifact may obscure color flow. Especially with heavy calcifications, such as plaque.
