Simplified ultrasound protocol for the exclusion of clinically significant carotid artery stenosis
Dominika Högberg1,2, Demosthenes Dellagrammaticas1, Björn Kragsterman1
1a Department of Surgical Sciences , Section of Vascular Surgery, Uppsala University , Uppsala , Sweden ;
Insights
A simplified ultrasound protocol effectively screens for significant carotid artery stenosis (>50%). This method shows high negative predictive value, suggesting its suitability for excluding serious carotid artery disease in screening settings.
Area of Science:
- Vascular Ultrasound
- Medical Imaging
- Cardiovascular Screening
Background:
- Carotid artery stenosis is a significant risk factor for stroke.
- Accurate screening methods are crucial for early detection and intervention.
- Conventional ultrasound assessment relies on peak systolic velocity (PSV) measurements.
Purpose of the Study:
- To evaluate a simplified ultrasound protocol for excluding clinically significant carotid artery stenosis.
- To assess the efficacy of a greyscale/mosaic method compared to PSV measurements.
Main Methods:
- Carotid ultrasound examinations were performed on 4,748 individuals (9,493 arteries).
- A simplified greyscale/mosaic protocol was compared against conventional PSV measurements.
- Stenosis was defined using North American Symptomatic Carotid Endarterectomy Trial (NASCET) criteria (>20% and >50%).
Main Results:
- The simplified protocol demonstrated moderate agreement (κ=0.455) with PSV for stenosis detection.
- For >50% stenosis, the protocol achieved 90% sensitivity and 97% specificity.
- The negative predictive value (NPV) for >50% stenosis was 100%, indicating high accuracy in excluding significant disease.
Conclusions:
- The simplified greyscale/mosaic ultrasound protocol is a valuable screening tool.
- It possesses a high negative predictive value for excluding >50% carotid stenosis.
- This method may be suitable for widespread screening to identify individuals needing further investigation.
Objectives:
To evaluate a simplified ultrasound protocol for the exclusion of clinically significant carotid artery stenosis for screening purposes.
Material And Methods:
A total of 9,493 carotid arteries in 4,748 persons underwent carotid ultrasound examination. Most subjects were 65-year-old men attending screening for abdominal aortic aneurysm. The presence of a stenosis on B-mode and/or a mosaic pattern in post-stenotic areas on colour Doppler and maximum peak systolic velocity (PSV) in the internal carotid artery (ICA) were recorded. A carotid stenosis was defined as The North American Symptomatic Carotid Endarterectomy Trial (NASCET) >20% and a significant stenosis as NASCET >50%. The kappa (κ) statistic was used to assess agreement between methods. Sensitivity, specificity, positive predictive (PPV), and negative predictive (NPV) values were calculated for the greyscale/mosaic method compared to conventional assessment by means of PSV measurement.
Results:
An ICA stenosis was found in 121 (1.3%) arteries; 82 (0.9%) were graded 20%-49%, 16 (0.2%) were 50%-69%, and 23 (0.2%) were 70%-99%. Eighteen (0.2%) arteries were occluded. Overall, the greyscale/mosaic protocol showed a moderate agreement with ICA PSV measurements for the detection of carotid artery stenosis, κ = 0.455. The sensitivity, specificity, PPV, and NPV for detection of >20% ICA stenosis were 91% (95% CI 0.84-0.95), 97% (0.97-0.98), 31% (0.26-0.36), and 97% (0.97-0.97), respectively. The corresponding figures for >50% stenosis were 90% (0.83-0.95), 97% (0.97-0.98), 11% (0.08-0.15), and 100% (0.99-1.00).
Conclusion:
Compared with PSV measurements, the simplified greyscale/mosaic protocol had a high negative predictive value for detection of >50% carotid stenosis, suggesting that it may be suitable as a screening method to exclude significant disease.
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