Abstract A068: Carotid Web Morphology Over Time: A Longitudinal Imaging Study

Introduction: Carotid webs (CW) are shelf-like fibrous intimal projections from the posterior wall of the carotid bulb and are associated with ischemic stroke, particularly in younger patients. While CWs are increasingly recognized, their natural history and potential to evolve over time remain poorly understood. We aimed to assess the morphological changes of CW over time using serial CT angiography (CTA). Methods: We retrospectively reviewed neck CTA scans performed at two health systems between January 2021 and June 2024 in adults whose radiology reports mentioned “web”. Confirmation of CW was based on published criteria, and then additional CTA were identified, if available. Patients with >1 CTA were included; for those with multiple scans, the first and last were included. Two trained, blinded raters independently measured CW features, and the averages were analyzed. To minimize the impact of intra-/inter-rater variability and differences in scan parameters/quality between studies, considerable change was defined as >2 SDs from baseline. Results: Among 214 patients with confirmed CW, 60 (28%) had >1 CTA and were included. Mean age was 57.9 (SD:13.9), 72% were female, and 7% (n=4) had bilateral webs (Table 1). After a median of 14.4 months (IQR:3.7-26.1) follow-up time, considerable morphologic changes were uncommon (Figure 1). In one patient, the web was absent on baseline CTA performed 9 years before follow-up CTA, leading to considerable change in all morphologic features. One web showed considerable decrease in length, and another demonstrated considerable reduction in thickness and base width, both likely attributable to thrombus suspected on baseline CTA (Table 2). Thrombus was suspected in 4 CWs on baseline CTA, with resolution on follow-up CTA. Overall, the vast majority of webs (>90%) remained morphologically stable over time. A weak positive correlation was observed between follow-up time and changes in CW angle (Kendall’s tau-b=0.17, p=0.047) and a similar trend for length change (tau-b=0.14, p=0.097). Conclusions: In this multicenter cohort, considerable change in CW morphology was rare and often attributable to thrombus dynamics. These findings suggest that CWs are largely static structural lesions. Absence of morphologic change may improve diagnostic confidence in distinguishing CWs from atherosclerotic plaques and dissections. Additional studies are needed to better characterize the genesis and natural history of CW.