Introduction: Carotid bifurcation is an important source of thrombus formation leading to distal embolization causing TIA and stroke. Although atherosclerotic stenosis involving this region is a well-known cause of stroke, non-stenotic conditions (producing <50% stenosis) affecting carotid bifurcation are increasingly recognized as a cause of stroke including sub-stenotic plaques and carotid webs. Prior studies focused on stenotic plaques, with very few studies investigating disturbed flow patterns associated with these conditions. We used time-resolved computed tomography angiography (CTA) to study hemodynamic features of carotid bifurcation lesions with ipsilateral stroke symptoms. Methods: Adult patients (≥18 years) with stroke symptoms (both TIA and ischemic stroke) in the distribution of anterior circulation with cryptogenic etiology were included. Arterial phase CTA with multiplanar reconstructions was used to assess morphology of carotid bifurcation lesion to classify the lesion into carotid web and carotid plaque. Time-resolved CTA was used to evaluate hemodynamic features suggestive of disturbed flow, specifically contrast stagnation and the presence/size of recirculation pockets. Large pocket (length ≥2× lesion height) was used as a proxy of greater hemodynamic disturbance. Hemodynamic findings were correlated with symptom status. Results: Ten patients (median age 53.5 years; 70% male) were analyzed, comprising 20 carotid bifurcations: carotid webs (n=6), plaques (n=8), and normal bifurcations (n=6). Contrast stagnation was observed in 4/6 (66.67%) carotid webs, with large recirculation pockets present in 3 (of 4 with stagnation). In contrast, 4/8 plaques (50%) showed stagnation with large recirculation pocket in 1 (of 4 with stagnation). No normal carotid bifurcation showed stagnation/recirculation pocket. Lesions with large recirculation pockets (4/4) were associated with ipsilateral symptoms. Conclusions: Carotid bifurcation with symptomatic lesions (webs and plaques) exhibits signs of hemodynamic disturbances on time-resolved CTA with the symptomatic side showing greater hemodynamic disturbance compared with asymptomatic lesions and normal carotid bifurcations. Disturbed flow was more pronounced in carotid webs than in plaques. Time-resolved CTA may provide an integrated assessment of morphology and hemodynamics, with potential value for risk stratification in patients with cryptogenic stroke.
Singh et al. (Thu,) studied this question.
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