AE Lab - Color Doppler Written Comp

What do Red and Blue represent with Doppler?

blue = away from transducer

red = towards transducer

Ideal Frame Rates

> 18 fps

length of color box does NOT affect frame rates

width of color box DOES affect frame rates

Color scale (what does it show?)

• # at the top and bottom of the color map represent the Nyquist limit (point at which aliasing occurs)

• Decreasing scale

  • Increases sensitivity to lower flows

  • Negative effect - causes aliasing

  • Overestimate regurgitation

• Increasing scale

  • Decreases sensitivity to lower flows

  • Underestimate regurgitation

Nyquist Limit

50-70 cm/sec

how do you know you have aliasing?

• color will wrap around to other side of scale (be a mix of red & blue)

How to optimize color gain

• turn all the way up until it speckles

• turn down slowly until speckling stops

• Too Low

  • Slower flows not to be seen

• Too High

  • Flows will appear worse than they are

IAS shunt flow

turn color scale down (below 40)

Benefits/uses of color Doppler

Evaluating regurgitation

• Through prosthetic/repaired valves

• Through aneurysms when they burst

• Through native valves

Evaluating origin, length or width of jets

• Useful in determining severity of regurgitation

Identifying turbulent flows & stenotic jets

• MS, PS, TS, AS

Guide for Spectral Doppler sample

• HOCM

• Regurgitation

• Stenosis

• Shunts

• Veins

• Better Color Doppler = Better Spectral Doppler

Pathologies you can assess with color Doppler

• stenosis

• regurgitation

• shunt flow

  • ASD, VSD, PFO, PDA

• Obstructions

  • HOCM

  • subaortic Membrane

• Flow through vessels 

  • Detect true/false lumen for aortic dissections

Best alignment to assess color

parallel to box / cursor

straight up & down

Regurgitant severity by color Doppler

origin & direction of jets

• center of valve

• in part of leaflet = perforation

• paravalvular

• eccentric / wrapping around chamber wall

length of jets

• just past valve = mild

• halfway through chamber = moderate

• going from valve —> touching end of chamber = moderate - severe

• at end of chamber and going past it (ie to pulm vns, to IVC) = severe

width of jets

• small = mild

• wider = severe

Recognize normal & abnormal color Doppler scales, and how to fix them

• different top & bottom #s

  • move baseline to normal

• switched colors (blue on top, etc)

  •