OBJECTIVES: 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. This study examines the relationship between DUS and cross-sectional imaging diagnoses of extracranial CAO.
METHODS: This single-institution retrospective analysis studied patients with CAO diagnosed by DUS from 2010-2021. Patients were identified in our office-based accredited vascular laboratory database. Imaging and clinical data was obtained via our institutional EMR.
RESULTS: Of our 140 patient cohort, 95 patients (67.9%) had DUS follow-up (mean 42.7±31.3 months). 75 patients (53.6%) had cross-sectional imaging of the carotids after CAO diagnosis; 18 (24%) underwent MR and 57 (76%) underwent CT. 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 and without cross-sectional imaging, 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). Demographics, comorbidities, and medical management of our cohort is shown in Table 1. Despite initial DUS diagnoses of carotid occlusion, 10 patients (13.3%) ultimately had cross-sectional imaging indicating non-occluded carotids; 6 of these 10 patients had stenoses of ~99%, 1 of 70-99%, 1 of 50-69%, and 1 of less than 50% on cross-sectional imaging. 7 patients had discordant cross-sectional imaging within 1 month of DUS CAO diagnosis. There were no significant relationships between imaging discrepancies and BMI, heart failure, upper body edema, carotid artery calcification, and neck hardware.
CONCLUSIONS: 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 more frequent surveillance as well as confirmatory CT or MR angiography. Digital subtraction angiography may be helpful in elucidating contributing factors to these imaging discrepancies, though it presents a more challenging risk-benefit profile. Table 1: Summary of Demographics, Comorbidities, and Medical Management
| No CSI, N = 651 | CSI, N = 751 | p-value | |
| Age at Index Study | 68.8 (10.2) | 70.6 (10.0) | 0.3 |
| Male Sex | 72.3% (47) | 65.3% (49) | 0.4 |
| Follow Up Period, Months | 40.0 (34) | 44.6 (29.3) | 0.2 |
| Symptomaticity at Index Study | 0.4 | ||
| Asymptomatic, incidental | 43.1% (28) | 46.7% (35) | |
| Asymptomatic, stenosis suspected | 15.4% (10) | 21.3% (16) | |
| Symptomatic (CVA/TIA) | 38.5% (25) | 32.0% (24) | |
| Unknown | 3.1% (2) | 0.0% (0) | |
| Active Smoking | 13.8% (9) | 16.0% (12) | 0.7 |
| Prior Smoking | 41.5% (27) | 45.3% (34) | 0.7 |
| Hypertension | 70.8% (46) | 74.7% (56) | 0.6 |
| Hyperlipidemia | 63.1% (41) | 64.0% (48) | >0.9 |
| Diabetes Mellitus | 30.8% (20) | 24.0% (18) | 0.4 |
| Chronic Kidney Disease | 6.2% (4) | 5.3% (4) | >0.9 |
| Coronary Artery Disease | 30.8% (20) | 30.7% (23) | >0.9 |
| History of Ipsilateral Stroke | 100.0% (7) | 100.0% (3) | |
| History of Carotid Revascularization | 12.3% (8) | 8.0% (6) | 0.4 |
| Antihypertensive | 53.8% (35) | 72.0% (54) | 0.026 |
| Aspirin | 58.5% (38) | 62.7% (47) | 0.6 |
| P2Y12 Inhibitor | 26.2% (17) | 21.3% (16) | 0.5 |
| Statin | 63.1% (41) | 70.7% (53) | 0.3 |
| Anti-Thrombotic Agent | 12.3% (8) | 10.7% (8) | 0.8 |
| 1Mean (SD); % (n) |
