Duplex Ultrasound and Cross-sectional Imaging in Carotid Artery Occlusion Diagnosis

Abstract

Investigations into imaging modalities in the diagnosis of extracranial carotid artery occlusion (CAO) have raised questions about the intermodality comparability of duplex ultrasound (DUS) and cross-sectional imaging. This study examines the relationship between DUS and cross-sectional imaging diagnoses of extracranial CAO. This single-institution retrospective analysis studied patients with CAO diagnosed by DUS imaging from 2010 to 2021. Patients were identified in our office-based accredited vascular laboratory database. Imaging and clinical data were obtained via our institutional electronic medical records. Our 140-patient cohort is characterized in Table I. A total of 95 patients (67.9%) had DUS follow-up (mean: 42.7 ± 31.3 months). Seventy-five patients (53.6%) had cross-sectional imaging of the carotids after CAO diagnosis; 18 (24%) underwent magnetic resonance angiography and 57 (76%) underwent computed tomography. Indications for cross-sectional imaging 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 cross-sectional imaging 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 nonimaged patients in antihypertensive medications (72% vs 53.8%, P = .04). Despite initial DUS diagnoses of carotid occlusion, 10 patients (13.3%) ultimately had cross-sectional imaging indicating nonoccluded carotids. Six of these 10 patients had stenoses of approximately 99%, one patient had 70% to 99%, one had 50% to 69%, and one had less than 50% on cross-sectional imaging. A total of 7 patients had discordant cross-sectional imaging within 1 month of DUS CAO diagnosis. The imaging comparison is displayed in Table II. When using cross-sectional imaging as confirmatory imaging, DUS imaging has a negative predictive value of 86.6% for the diagnosis of CAO within our cohort. In our experience, duplex diagnosis of CAO is associated with a greater than 10% discordance when compared with cross-sectional imaging. These patients may benefit from closer surveillance as well as confirmatory CT or magnetic resonance angiography. Digital subtraction angiography may be helpful in elucidating contributing factors to these imaging discrepancies.Table IPatient characteristics (N = 140)DemographicsValue, n (%)Mean age at diagnosis, years69.7 (47.8-91.2)Female44 (31.4)Comorbidities Active smoking21 (15.0) Prior smoking61 (43.6) Hypertension101 (72.3) Hyperlipidemia90 (63.6) Diabetes mellitus38 (27.1) Coronary artery disease8 (5.7) Chronic kidney disease43 (30.7) Cognitive decline5 (3.6)Medications at diagnosis Antihypertensive88 (63.4) Aspirin85 (60.7) Statin94 (67.1) P2Y12 inhibitor33 (23.6) Anticoagulation16 (11.4) Open table in a new tab Table IIComparison of cross-sectional imaging to initial ultrasoundOccluded on duplexTotalPatent on cross-sectional imaging10 (false negatives)10Occluded on cross-sectional imaging65 (true negatives)65Total75 Open table in a new tab