Quantifying Carotid Stenosis: History, Current Applications, Limitations, and Potential: How Imaging Is Changing the Scenario

Abstract

Carotid artery stenosis is a major cause of morbidity and mortality. The journey to understanding carotid disease has developed over time and radiology has a pivotal role in diagnosis, risk stratification and therapeutic management. This paper reviews the history of diagnostic imaging in carotid disease, its evolution towards its current applications in the clinical and research fields, and the potential of new technologies to aid clinicians in identifying the disease and tailoring medical and surgical treatment.

Keywords: CTA; DSA; MRA; artificial intelligence; carotid disease; carotid endarterectomy; carotid stenosis; near-occlusion; plaque-RADS; vulnerable carotid plaque.

Figure 1

Schematic representation of ICA stenosis, illustrating NASCET and ECST measurement methods. B, luminal diameter at the site of maximal narrowing. A, diameter of the normal distal ICA well beyond the bulb, where the artery walls are parallel. C, diameter of the estimated original width of the ICA at the site of maximal narrowing.

Figure 2

Schematic representation of the direct mm method.

Figure 3

Drawing illustrating the projectional artifact. According to the viewpoint, the minimal luminal diameter (MLD) can appear smaller (larger stenosis) or bigger (smaller stenosis).

Figure 4

Schematic representation of near-occlusion with the recently proposed CTA identification criteria. (A) without full collapse on the left image; (B) with full collapse on the left image.

Figure 5

Graph illustrating the relationship between area reduction and diameter reduction in a completely concentric stenosis.

Figure 6

Schematic representation of the different Carotid Plaque RADS categories from 1 to 4, ancillary features, and modifiers. Presentation concept based on Saba et al. [96].