Cerebrovascular Duplex Examinations Flashcards
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Read the first 7 Cerebrovascular Duplex Examinations flashcards as text
During TCD monitoring for microembolic signals (MES), an embolic signal is characterized by which property?
Answer: Unidirectional, high-intensity, transient signal lasting <300 ms within the Doppler spectrum
MES are unidirectional, high-intensity transient signals <300 ms duration occurring randomly within the cardiac cycle, distinct from artifacts.
Which clinical scenario would MOST warrant a cerebrovascular duplex examination as the initial imaging study?
Answer: Transient ischemic attack with hemispheric symptoms
Carotid duplex is the first-line investigation for hemispheric TIA to identify treatable carotid stenosis as a potential embolic source.
What is the clinical significance of identifying a carotid 'string sign' on duplex ultrasound?
Answer: It indicates near-total occlusion with a thin trickle of residual flow
The string sign describes a thread-like trickle of flow through a near-total ICA occlusion, an important distinction from complete occlusion since it may still be treatable.
Fibromuscular dysplasia (FMD) of the internal carotid artery most commonly involves which segment and appears as what pattern on duplex?
Answer: Mid-to-distal ICA; alternating stenoses and dilations producing a 'string of beads' appearance
FMD characteristically affects the mid-to-distal cervical ICA, producing the classic angiographic and ultrasound 'string of beads' pattern of alternating stenoses and aneurysmal segments.
During carotid duplex, spectral broadening is defined as filling in of which portion of the Doppler waveform?
Answer: The temporal window beneath the systolic peak (systolic window)
Normal laminar flow produces a clear systolic window (spectral window) under the waveform envelope; spectral broadening fills this window, indicating turbulent or disturbed flow.
Which duplex finding is the BEST indicator to differentiate ICA occlusion from severe near-total occlusion when color Doppler shows no flow?
Answer: Detection of a trickle of flow using power Doppler or contrast-enhanced ultrasound
Power Doppler or CEUS can detect residual trickle flow in near-occlusion that conventional color Doppler misses, changing patient management.
A patient undergoing carotid stenting has post-procedure duplex showing PSV of 240 cm/s at the stent. What is the most appropriate clinical interpretation?
Answer: In-stent restenosis ≥50% requiring close surveillance
Post-carotid stenting velocity criteria differ from CEA; PSV ≥220–240 cm/s within a stent generally indicates ≥50% in-stent restenosis requiring surveillance or re-intervention.