Detection of Carotid Webs by CT Angiography, High-Resolution MRI, and Ultrasound

BACKGROUND AND PURPOSE

We sought to examine carotid webs (intimal variant fibromuscular dysplasia) by studying their clinical features and imaging profiles.

METHODS

All patients (n = 893) of the Department of Neurology at Beijing Tiantan Hospital between January and December 2019 were retrospectively reviewed for computed tomography angiography (CTA), high-resolution magnetic resonance imaging (HRMRI), and Doppler ultrasound data. Carotid webs were identified by two experienced neuroimaging experts according to the characteristics of a thin intraluminal filling defect along the posterior wall of the carotid bulb on sagittal CTA and a septum structure in arteries on axial CTA.

RESULTS

We found eight carotid web patients by CTA and Doppler ultrasound. Four of eight (50%) carotid webs were observed in the bilateral carotid arteries and other four of eight (50%) were ipsilateral. The mean age of the 8 patients was 50.75 (range 38-65) years; two were in women. Six of 8 patients (75%) with carotid webs had acute ischemic stroke. Two-thirds of patients with ischemic stroke were treated with carotid revascularization. Doppler ultrasound indicated that the septum projected into the carotid arteries in all patients. Half of the carotid web patients underwent HRMRI, showing features consistent with CTA findings. The Cohen's kappa coefficient for interobserver agreement in diagnosing carotid webs was .76.

CONCLUSIONS

Doppler ultrasound combined with CTA and HRMRI is effective and reliable method to identifying carotid webs, which may be associated with stroke.

Carotid webs management in symptomatic patients

BACKGROUND

Atypical fibromuscular dysplasia (AFMD), also known as carotid web, is a rare underdiagnosed shelf-like fibrous tissue arising from the posterior carotid artery bulb that is a cause of cryptogenic stroke of the anterior cerebral vascularization. Despite the recurrence and severity of strokes caused by embolization associated with AFMD, there are no recommendations on the best strategy to manage single and bilateral lesions, which have unsatisfactory outcomes when treated with medical treatment exclusively.

METHODS

From January 2016 to April 2019, 365 patients were operated on for a carotid stenosis in our institution. This cohort included 11 patients (3%), with a median age of 41 years (range, 39-51 years), referred by a stroke unit, treated for a symptomatic (10 strokes and 1 recurrent transient ischemic attack) AFMD lesion. Preoperative workup revealed a contralateral similar lesion in 45% of patients (5/11), which all also underwent surgery during a subsequent hospitalization. The diagnosis was confirmed by histologic examination when open surgery was performed. The 30-day and 1-year outcomes were retrospectively reviewed.

RESULTS

Of the 16 AFMD lesions operated, 13 were treated by open surgery (2 by classic endarterectomy and 11 by internal carotid resection-anastomosis) and 3 by carotid artery stenting, respectively, with a mean delay of 85.5 days and 20.5 days after the latest stroke. There was one complication after stenting (external iliac rupture) that was treated by a covered stent, and no perioperative complications after open surgery. The follow-ups at 30 days and 1 year were uneventful for all patients, without any deaths or stroke recurrences.

CONCLUSIONS

Symptomatic AFMD is a rare cause of cryptogenic stroke. Bilateral lesions are frequent. Early intervention is associated with favorable perioperative and 1-year outcomes. Open surgery is the first-line therapeutic option in this young patient population.

Symptomatic carotid web in a female patient

We describe a 47-year-old female patient with a carotid web and ischemic stroke. A carotid web is a membrane-like shelf of tissue, predominantly affecting the intimal layer of the arterial wall, usually extending from the posterolateral wall of the carotid artery into the lumen, typically at the origin of the internal carotid artery just beyond the bifurcation. It is considered to be an under-recognized etiology of ischemic stroke in young and middle-aged patients. Typically, these patients do not show any coexistent or only few vascular risk factors. Digital subtraction angiography, computer tomography angiography, magnetic resonance angiography, and color-coded duplex sonography are able to identify carotid webs. Therapy strategies include conservative therapy with intake of antiplatelet agents and anticoagulants, or carotid endarterectomy or carotid artery stenting. Optimal therapy strategy remains open. A considerable rate of recurrent cerebrovascular ischemic events has been reported in patients with a symptomatic carotid web and conservative therapy. More data are needed on prevalence, diagnosis, prognosis and therapy of patients with an asymptomatic or a symptomatic carotid web.

Subject Codes: [13] Cerebrovascular Disease/Stroke, [44] Acute Cerebral Infarction, [193] Clinical Studies

Carotid artery webs in embolic stroke of undetermined source with large intracranial vessel occlusion

Background

Whether carotid artery web can be considered as a potential source of arterial thromboembolism in ischemic stroke remains uncertain.

Aims

In a large sample of individuals with large intracranial artery occlusion, we compared the prevalence of carotid artery webs between patients with and without embolic stroke of undetermined source.

Methods

In a single-center study of consecutive patients with anterior circulation ischemic stroke referred for mechanical thrombectomy, the presence of carotid artery web was systematically assessed by two independent readers. Thereafter, its prevalence was compared between patients with and without embolic stroke of undetermined source.

Results

Among 466 patients of whom 12% were considered to have had an embolic stroke of undetermined source, ipsilateral carotid artery web was detected in 1.9% (confidence interval 95% = 0.7–3.1). Ipsilateral carotid artery web was more frequent in embolic stroke of undetermined source than in the rest of the sample (10.7% (confidence interval 95% = 2.7–18.7] vs. 0.7% (0–1.5), P < 0.001). This difference remains significant after adjustment for sex, age, and vascular risk factor (odds ratio: 12.5 (2.1–72), P = 0.005) or after exclusion of patients with any other bulb wall thickening ( P = 0.025). In contrast, the difference of prevalence of contralateral carotid artery web between the two groups did not reach statistical significance (2.4% vs. 1.9%, P = 0.6).

Conclusions

Our results suggest that the presence of a carotid artery web might be considered as a potential source of large intracranial artery embolism. Longitudinal studies are needed to assess the exact risk of recurrence associated with these lesions.

Prevalence of Ipsilateral Nonstenotic Carotid Plaques on Computed Tomography Angiography in Embolic Stroke of Undetermined Source

Background and Purpose- Embolic stroke of undetermined source (ESUS) constitutes a large proportion of acute ischemic stroke. It is crucial to identify possible stroke etiologies in this patient subgroup to individually tailor secondary stroke prevention strategies. This study aimed to assess the prevalence of carotid plaques causing <50% stenosis in ESUS patients on computed tomography angiography and the association of these plaques with ipsilateral strokes. Methods- Patients from INTERRSeCT-a multicenter prospective study of patients with acute ischemic stroke-were included in this study if their stroke etiology was not large artery atherosclerosis (>50% stenosis), and neck computed tomography angiography was obtained. Degree of stenosis (<30% versus 30%-50%), maximum plaque thickness, degree of plaque calcification (<50% versus ≥50%), plaque irregularity, ulceration, hypodensity, carotid web, and focal vessel outpouching were assessed for both carotid arteries on computed tomography angiography. Prevalence of carotid plaques with <50% stenosis (nonstenotic plaques), ipsilateral and contralateral to the stroke, in ESUS patients was determined and compared with non-ESUS patients. Features of these plaques with versus without ipsilateral stroke in ESUS patients were compared. Uni- and multivariable logistic regression was performed to determine associations between nonstenotic carotid plaque, plaque characteristics, and ipsilateral stroke in ESUS patients. Results- Four hundred forty-six patients were included in the study (median age, 73 years; 218 men), 138 of which were ESUS patients (median age, 70 years; 61 men). Nonstenotic carotid plaques (with <50% stenosis) were present in 54 of 138 (39.1%) ESUS patients. Twelve (8.7%) patients had bilateral carotid plaques. Forty (60.6%) of these plaques were ipsilateral and 26 (39.4%) contralateral to the side of the stroke (P=0.004). Nonstenotic carotid plaques were significantly associated with ipsilateral strokes (adjusted odds ratio, 1.83 [95% CI, 1.05-3.18]). Conclusions- In patients with ESUS, nonstenotic carotid plaques were significantly more common on the side of the ischemic stroke, suggesting that these plaques could be a potential stroke etiology in patients in whom the ischemic stroke is classified currently as ESUS.

Carotid Web Stenting

Background: Carotid webs are luminal, shelf-like protrusions at the carotid bulb. Considered to be a variant of fibromuscular dysplasia, carotid webs have been observed principally in African American females. The association between carotid webs and recurrent ischemic strokes continues to be established as patients without traditional stroke risk factors are found to have carotid webs as the only possible cause of symptomatic deficits. The majority of patients undergo endarterectomy; few stent placements are reported. We present the case of an African American female who underwent stent placement for treatment and secondary prevention of stroke attributed to a carotid web. Case Report: A 33-year-old African American female presented with acute onset left hemiparesis and left facial droop. Alteplase was administered; multiphase head and neck computed tomography angiography revealed an occlusion of the right middle cerebral artery with a web at the carotid bulb. Aspiration catheter thrombectomy achieved a Thrombolysis in Cerebral Infarction (TICI) score of 3. She was placed on 2 antiplatelet agents, and 3 weeks later she underwent stent placement. Follow-up digital subtraction angiography at 3 months showed obliteration of the right carotid artery web and satisfactory integration of the stent into the vessel wall. She was reassessed at 1 year and reported no neurologic symptoms. Conclusion: Although carotid webs are most commonly treated with endarterectomy, they may be amenable to stent therapy with favorable clinical outcomes as shown with this patient.

Flow Patterns in Carotid Webs: A Patient-Based Computational Fluid Dynamics Study

BACKGROUND AND PURPOSE

Carotid webs are increasingly recognized as an important cause of (recurrent) ischemic stroke in patients without other cardiovascular risk factors. Hemodynamic flow patterns induced by these lesions might be associated with thrombus formation. The aim of our study was to evaluate flow patterns of carotid webs using computational fluid dynamics.

MATERIALS AND METHODS

Patients with a carotid web in the Multicenter Randomized Clinical Trial of Endovascular Treatment of Acute Ischemic Stroke in the Netherlands (MR CLEAN) were selected for hemodynamic evaluation with computational fluid dynamics models based on lumen segmentations obtained from CT angiography scans. Hemodynamic parameters, including the area of recirculation zone, time-averaged wall shear stress, transverse wall shear stress, and the oscillatory shear index, were assessed and compared with the contralateral carotid bifurcation.

RESULTS

In our study, 9 patients were evaluated. Distal to the carotid webs, recirculation zones were significantly larger compared with the contralateral bifurcation (63 versus 43 mm², P = .02). In the recirculation zones of the carotid webs and the contralateral carotid bifurcation, time-averaged wall shear stress values were comparable (both: median, 0.27 Pa; P = .30), while transverse wall shear stress and oscillatory shear index values were significantly higher in the recirculation zone of carotid webs (median, 0.25 versus 0.21 Pa; P = .02 and 0.39 versus 0.30 Pa; P = .04). At the minimal lumen area, simulations showed a significantly higher time-averaged wall shear stress in the web compared with the contralateral bifurcation (median, 0.58 versus 0.45 Pa; P = .01).

CONCLUSIONS

Carotid webs are associated with increased recirculation zones and regional increased wall shear stress metrics that are associated with disturbed flow. These findings suggest that a carotid web might stimulate thrombus formation, which increases the risk of acute ischemic stroke.

Multimodality Imaging in Carotid Web

Purpose: Carotid web (CaW) is an underrecognized cause of cryptogenic stroke in young patients. The optimal imaging for CaW is unknown. We aim to evaluate the diagnostic accuracy of diverse imaging modalities for the diagnosis of CaW.

Methods: Retrospective analysis of institutional neurovascular database was performed to identify patients with multimodal (CT angiogram–CTA, digital subtraction angiogram–DSA, and/or ultrasound–US) imaging diagnosis of CaW or atherosclerosis. Baseline clinical demographics were recorded. Blinded image analysis was performed for each imaging modality by separate readers. Discrepancies were settled by consensus. Two-sided Cohen's Kappa (κ) coefficient was used to evaluate the inter-rater agreement for the etiological diagnosis between imaging modalities.

Results: Thirty patients/60 carotids were evaluated by CTA and 55 carotids were included. Patients with symptomatic CaW (n = 20), compared to individuals with atherosclerosis (n = 10), were younger (49 ± 9 vs. 60 ± 8 years; p < 0.01), more commonly female (75% vs. 30%; p = 0.01), and less frequently presented vascular risk factors: Hypertension (40% vs. 100%; p < 0.01), hyperlipidemia (0% vs. 50%; p < 0.01), diabetes (10% vs. 40%; p = 0.05), and smoking (5% vs. 70%; p < 0.01). High inter-rater correlation strength existed for CTA (n = 55; κ = 0.88; p < 0.0001) and DSA (n = 28; κ = 0.86, p < 0.0001) readers for lesion diagnosis while US inter-rater agreement was lower (κ = 0.553; p = 0.001). Across modalities CTA and DSA shared very high strength of agreement (κ = 0.92; p < 0.0001), compared to a less pronounced agreement between US and CTA (κ = 0.553; p = 0.001). The strength of correlation between DSA-CTA was significantly more robust as compared to US-CTA (Z = 3.58; p = 0.0003).

Conclusion: CTA and DSA demonstrated comparable and superior performance as compared to US in the diagnosis of CaW.

Transient Ischemic Attack and Carotid Web

BACKGROUND AND PURPOSE

Carotid web was recognized as a cause of ischemic stroke. We sought to determine the clinical and imaging profiles of patients with a carotid web as well as its association with TIA.

MATERIALS AND METHODS

A retrospective review of carotid CT angiography studies and brain MR imaging in patients with TIA during the past 3 years (n = 135) was performed to determine the presence of carotid webs by 2 experienced neuroradiologists according to previously published criteria. Demographics and clinical and imaging characteristics are shown by descriptive statistics for patients with an identified carotid web. The agreement in the detection of carotid webs between 2 neuroradiologists was examined using κ statistics.

RESULTS

There were 12 (8.9%) carotid webs at the symptomatic bifurcation and 1 carotid web (0.7%) at the asymptomatic bifurcation, and no hyperintensity was seen on DWI of these 12 patients. Eight of these 12 (75%) patients with a carotid web were women. None of the 12 patients with a carotid web had major risk factors or other causes of TIA. Fair-to-good interobserver agreement (κ = 0.87) was seen for diagnosing a carotid web with CT angiography. The rate (10/12, 83.3%) of short-term recurrent episodes of TIA in patients with TIA with a carotid web was significantly higher than that of patients without a carotid web (15/123, 12.2%) (P < .001).

CONCLUSIONS

The incidence of carotid web in patients with TIA was 8.9%. There is an association between carotid web and patients with TIA without other identified risks. Carotid web may be an underestimated risk factor for TIA.