Colour Doppler Flashcards
Varicose veins
Failing valves result in reflux, depicted by colour Doppler & eventually vein falls stretch & billow
DVT
Clarifies if something is partially or completely occluded
- common to get mural thrombosis in aneurysms
Anechoic spaces
Use colour Doppler to check all anechoic spaces found
- eg; renal cyst/hydronephrosis could be a renal aneurysm
Ventricular Septal Defect (VSD)
Directional power Doppler is utilised to depict the hole
Normal artery layers
1- intimal layer (inner wall) - echogenic inner border
2- media layer - hypoechoic
3- adventitia - echogenic
Plaque formations
Usually found in intima-media region
Calcific plaque
- takes a long time to form; has hyperechoic edge that often causes shadowing
- AKA irregular (dystrophic) echogenic plaque
- can obscure/shadow Doppler shift & mimic focal segment of occlusion
- use pulse wave spectoral interrogation to show velocities & clarify shadowing Vs occlusion
Avoiding shadows
- shift our interrogation angle to circumnavigate the plaque
- may need to roll/move Pt to diff scanning position!!!
PW Spectoral dooper
- shows a trace which quantifies the velocity of blood moving during time (measure the PSV or EDV)
- offers real time info* about the vessel (low Vs high resistance)
- allows us to distinguish an artery from a vein
- shows changes in anatomy of the vessel at the same time as seeing the velocity info*
- allows us to hear blood as it pulses
- allows identification of cause of an audible bruit (post auscultating hear sounds)
Operator error occlusions
- vertebral vein, which has slow moving flow… involves shadowing from the vertebrae & without adjusting the colour scale/bandwidth it may look like an occlusion
Stenosis
- comparing velocities in normal artery Vs where stenosis occurs
- get graded on dividing the peak velocity of the normal Vs the stenosed region: 4 req prompts surg review
Trouble shooting
Aliasing with No narrowing of the lumen - It’s YOU & yr machine setting not the Pt
Claudication
- caused by stenosis in the leg arteries
- results in leg pain/weakness
- PVD results also
- common in diabetics & smokers
We must measure Pre-stenosis-Post velocities to compare all of them!!!
Fake aliasing
- the probe frequency is too high (lower freq* probes are able to demonstrate high velocity flow more appropriately)
- colour PRF scale is set too low
- spectral window is not ‘filled in ‘ & there’s No spectral broadening
- No elevation in upstream (a region prox* to the aliasing demonstrate the same vel* as the next segment)
- No post-stenotic turbulence
High resistance wave form
= high peak, potentially biphasic, or even triphasic, but NOT a continuous wave form between pulses
Seen in:
- peripheral limbs
- ECA (extern* carotid art)of the face
- IMA (inferior mesenteric Art) to bowel
- MCA (medial cerebral art*) in foetal brain
Low resistance waveform
= monophasic looking, drawn out w No gaps between pulses, spongy like brain behaviour draws up the blood during diastole (doesn’t return to 0 on the spectrum)
- internal carotid art*
- renal arteries
- vertebral artery - feeds cerebellum
- umbilical artery - from placenta to baby (can be used to detect lack of supply)
Abnormal patterns
Tardis Parvus - delayed pattern/pulse across time (no quick upstroke) & lower peak
Lack of movement at all
Pitfall:
Tardis Parvus can be mimicked/simulated by inappropriately set scale & trace is minuscule… it could look like it!!
* reduce yr scale to ensure the waveform reaches across the whole scale to ensure U can see the whole waveform
High risk plaque
- two diff echogenicitis - heterogeneous plaque
- hypoechoic plaque = soft & unstable!!
- the dark the plaque, the higher the risk!! Independent of degrees of occlusion
Over/Underestimating plaque
Be aware of how the angle may change the quantification of an occlusive plaque
Highly fragile plaque
- demonstrate any hypoechoic plaque from multiple planes & complete the sheet to depict the shape & composition of the plqur
Ulcerative plaque
Need to depict:
- cavity within the plaque
- cavity is sharply marginated
- there is flow within the cavity
Embolus
- Plaque gets weakened across time
- plaque fissure gets filled w blood/clot/plaque
- rupture of plaque can cause embolisation of plaque
Why would be use Power Doppler
- it is more sensitive than colour Doppler - tho sometimes U need to turn down the gain
- ## doesn’t rely upon angular inception - though can be clear with some angle
Wall Thump waveform
- flow hitting against a ‘wall’, no through flow!!
- shows some forward flow & nearly instantaneous/simultaneous backward jolt in flow
Subclavian Steal Syndrome
Reversal of blood flow in vertebral artery due to reduced flow into subclavian artery, eg; to feed an arm
Dissections
True lumen Vs false lumen
Mirror artefact can micmic same tho
- intimas are not usually so bright & may create a mirror artifact
Fibromuscular displasia
- aliasing in arteries due to Dx
- normal malformations in these Pts
- long segments & younger Pts
