title: Direct B-mode NASCET-style stenosis measurement and Doppler ultrasound as parameters for assessment of internal carotid artery stenosis.
abstract: Doppler ultrasound grading of internal carotid artery (ICA) stenosis using the two parameters of spectral analysis and internal carotid to common carotid artery peak systolic velocity (ICA/CCA PSV) ratio is well established. The improvements in B-Mode ultrasound image quality now make direct ultrasound NASCET-style stenosis measurement possible. We demonstrate that longitudinal B-mode imaging can produce accurate North American Symptomatic Carotid Endarterectomy Trial (NASCET) style measurements which have good correlation with angiographic images. Ultrasound B-mode stenosis measurement provides a third parameter which can be used in conjunction with the two Doppler parameters for the assessment of ICA stenosis. Taking the highest grade of stenosis of the three parameters produces a sensitivity of 100% for the detection of greater than 50% and greater than 80% stenosis with specificity of 66 and 90%, respectively. The performance of satisfactory B-mode imaging against digital subtraction angiography (DSA) was very encouraging. When the B-mode stenosis measurement showed a normal ICA, the positive predictive value (PPV) of the DSA being normal was 94%. When the B-mode stenosis measurement was 35% or less, the PPV of the DSA stenosis being 35% or less was 93%. These excellent results support the use of good quality B-Mode NASCET style stenosis measurement as the initial ultrasound measurement, with Doppler ultrasound only being performed when the B-mode stenosis measurement is greater than 35% or if the B-mode image is unsatisfactory. This approach would save considerable time enabling better utilization of ultrasound resources.
authors.affiliation: Radiology Department, Royal Melbourne Hospital, Parkville, Victoria, Australia. rotstein@bigpond.com
authors.forename: Andrew H
authors.initials: AH
authors.lastname: Rotstein
authors.forename: Robert N
authors.initials: RN
authors.lastname: Gibson
authors.forename: Paula M
authors.initials: PM
authors.lastname: King
mesh_terms: D015901:Angiography, Digital Subtraction; D002343:Carotid Artery, Internal / Q000000981:diagnostic imaging*; D016893:Carotid Stenosis / Q000000981:diagnostic imaging*; D006801:Humans; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D018608:Ultrasonography, Doppler