U-King-Im JMKS et al. (2004) Measuring carotid stenosis on contrast-enhanced magnetic resonance angiography. Stroke 35: 2083–2088

Established techniques for measuring the severity of internal carotid artery (ICA) stenosis include the NASCET, ESCT and CC methods. Of these, only NASCET has been validated for use with contrast-enhanced magnetic resonance angiography (CEMRA), which is fast replacing intra-arterial digital subtraction angiography (DSA) as the modality of choice. U-King-Im et al. have compared the diagnostic performance and reproducibility of the NASCET, ESCT and CC methods on CEMRA, using DSA as the reference standard.

Symptomatic patients with suspected ICA stenosis (n = 142) underwent DSA and CEMRA, providing 284 arteries for analysis. All angiograms were reviewed independently by three experienced neuroradiologists and the maximum stenosis was calculated using the NASCET, ECST and CC methods. Stenosis was then classified as mild, moderate, severe or complete occlusion.

Intermodality correlation and agreement were similar for the three methods. For the identification of DSA-defined severe stenosis on CEMRA, there were no significant differences between the three measurement methods for specificity, positive predictive values or negative predictive values. Sensitivity, however, was significantly lower using ESCT (78.9%) than with NASCET (93.0%) or CC (87.7%).

The authors conclude that all three methods are adequate for use with DSA but that NASCET is the most appropriate measurement method when using CEMRA. They recommend that other non-invasive modalities should also be validated according to the measurement method.