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Accuracy of carotid duplex is laboratory specific and must be determined by internal audit
P J Curley1, L Norrie, A Nicholson
1Department of Vascular Surgery, Hull Royal Infirmary, U.K.
Insights
Carotid duplex accurately predicts internal carotid artery stenosis, but criteria vary by lab. A local audit of duplex and angiography is crucial before relying solely on duplex to avoid preoperative angiography.
Area of Science:
- Vascular Surgery
- Diagnostic Imaging
- Cardiovascular Medicine
Background:
- Internal carotid artery stenosis is a significant risk factor for stroke.
- Carotid duplex ultrasound is a non-invasive tool for assessing stenosis severity.
- Accurate prediction of stenosis is vital for guiding treatment decisions.
Purpose of the Study:
- To evaluate the diagnostic accuracy of carotid duplex ultrasound in identifying 70% internal carotid artery stenosis.
- To assess the predictive value of peak systolic velocity (PSV) thresholds.
- To determine the necessity of laboratory-specific validation of duplex criteria.
Main Methods:
- Retrospective review of patients undergoing both carotid duplex and angiography.
- Carotid duplex examinations used peak systolic velocity (PSV) as the primary endpoint.
- Angiography (arch aortography and selective catheterization) was performed, with stenosis calculated using the ECST method.
Main Results:
- A PSV threshold of 130 cm/s demonstrated 96% sensitivity and 67% specificity for detecting 70% stenosis.
- A higher PSV threshold of 250 cm/s resulted in 37% sensitivity and 96% specificity.
- These findings highlight the trade-off between sensitivity and specificity based on the chosen PSV cutoff.
Conclusions:
- Carotid duplex criteria are not universally applicable across different vascular laboratories.
- Laboratory-specific audits comparing duplex findings with angiography are essential.
- Such audits are critical before discontinuing preoperative angiography for carotid disease assessment.
Objective:
To assess the accuracy of carotid duplex in a single vascular laboratory at the prediction of an angiographic 70% internal carotid artery stenosis.
Design:
A retrospective review of all patients who underwent both carotid duplex and angiography in a 1-year period at a vascular unit which participates in the ACST trial.
Methods:
Peak systolic velocity was used as a primary end-point in carotid duplex examinations with a PSV > 130 cm/s used as an indication for angiographic assessment. Biplanar arch aortography and selective carotid catheterisation were performed as indicated and diameter reduction calculated by the ECST method.
Results:
The sensitivity of 130 cm/s for the detection of a 70% stenosis was 96% and the specificity 67%. If a PSV of 250 cm/s were used the sensitivity would be only 37% and specificity 96%.
Conclusions:
Applying duplex criteria from one centre to another is inappropriate. Laboratory specific audit of duplex and angiography is essential before deciding to abandon preoperative angiography for carotid disease.