Plaque contact surface area and lumen volume predict stroke risk in extracranial carotid artery stenosis

The standard indication for intervention in asymptomatic disease is currently percent stenosis in the internal carotid artery as measured by the North American Symptomatic Carotid Endarterectomy Trial (NASCET) method, which remains limited in discriminating power. Computed tomography angiography (CTA) is widely used to calculate NASCET stenosis, but also offers the opportunity to analyze carotid artery plaques from a morphological perspective that has not been widely used. We aim to improve stroke risk stratification of patients with carotid artery stenosis using plaque three-dimensional (3D) modeling and image analysis. Patients with computed tomography angiographies appropriate for 3D reconstruction were identified from a National Institutes of Health-designated stroke center database, and carotid arteries were segmented and analyzed using software algorithms to calculate contact surface area (CSA) between the plaque and blood flow, and volume of the flow lumen within the region of the plaque (lumen volume [LV]). These novel parameters factor in the 3D morphometry inherent to each carotid plaque and were compared between stroke and nonstroke groups. A total of 134 carotid arteries were analyzed, 33 of which were associated with an ipsilateral stroke. Plaques associated with stroke demonstrated statistically significant increases in average CSA (541.52 mm2) and LV (394.64 mm3) when compared with those not associated with stroke (371.18 mm2 and 245.92 mm3, respectively). When comparing area under the receiver operating characteristics curve between NASCET (0.65) percent stenosis, CSA (0.74), and LV (0.77), both CSA and LV demonstrated more favorable values in predicting stroke risk in patients with carotid stenosis. The data presented here demonstrate morphological features of carotid plaques that are independent of NASCET criteria stratification and may present an improved method in assessing stroke risk in patients with carotid artery stenosis.