Duplex ultrasound and cross-sectional imaging in carotid artery occlusion diagnosis

Investigations into imaging modalities in the diagnosis of extracranial carotid artery occlusion (CAO) have raised questions about the inter-modality comparability of duplex ultrasound (DUS) and cross-sectional imaging (CSI). This study examines the relationship between DUS and CSI diagnoses of extracranial CAO.

This single-institution retrospective analysis studied patients with CAO diagnosed by DUS from 2010 to 2021. Patients were identified in our office-based accredited vascular laboratory database. Imaging and clinical data was obtained via our institutional electronic medical record. Primary outcome was discrepancy between DUS and CSI modalities. Secondary outcomes included incidence of stroke and intervention subsequent to CAO diagnosis.

Of our 140-patient cohort, 95 patients (67.9%) had DUS follow-up (mean, 42.7 ± 31.3 months). At index duplex, 68.0% of individuals (n = 51) were asymptomatic. Seventy-five patients (53.6%) had CSI of the carotids after DUS CAO diagnosis; 18 (24%) underwent magnetic resonance imaging and 57 (76%) underwent computed tomography. Indications for CSI included follow-up of DUS findings of carotid stenosis/occlusion (44%), stroke/transient ischemic attack (16%), other symptoms (12%), preoperative evaluation (2.7%), unrelated pathology follow-up (9.3%), and outside institution imaging with unavailable indications (16%). When comparing patients with CSI and those without, there were no differences with regard to symptoms at diagnosis, prior neck interventions, or hypertension. There was a significant difference between cross-sectionally imaged and non-imaged patients in anti-hypertensive medications (72% vs 53.8%; P = .04). Despite initial DUS diagnoses of carotid occlusion, 10 patients (13.3%) ultimately had CSI indicating patent carotids. Four of these 10 patients had stenoses of ∼99% (with 1 string sign), four of 70% to 99%, one of 50% to 69%, and one of less than 50% on CSI. The majority of patients (70%) had CSI within 1 month of the index ultrasound. There were no significant relationships between imaging discrepancies and body mass index, heart failure, upper body edema, carotid artery calcification, and neck hardware. Eight individuals (10.7%) underwent ipsilateral revascularization; 62.5% (n = 5) were carotid endarterectomy procedures, and the remaining three procedures were a transcervical carotid revascularization, subclavian to internal carotid artery bypass, and transfemoral carotid artery stenting. Eight patients (10.7%) underwent contralateral revascularization, with the same distribution of procedures as those ipsilateral to occlusions. Two of the 10 patients with discrepancies underwent carotid endarterectomy, and one underwent carotid stenting.

In our experience, duplex diagnosis of CAO is associated with a greater than 10% discordance when compared with CSI. These patients may benefit from closer surveillance as well as confirmatory computed tomography or magnetic resonance angiography. Further work is needed to determine the optimal diagnostic modality for CAO.