Territory-based ultrasound assessment for extracranial and vertebrobasilar arterial stenosis and carotid plaque vulnerability: a multicentre comparison with digital subtraction angiography and histopathology

Introduction The diagnostic performance of ultrasound-based vascular assessment may vary by anatomical territory. We evaluated territory-specific ultrasound techniques for cervicocerebral arterial stenosis and compared cervical duplex ultrasound (CDU) with computed tomography angiography (CTA) for identifying carotid plaque vulnerability. Methods This retrospective multicentre study included 234 patients with ultrasound-based assessment, CTA and digital subtraction angiography (DSA) examinations conducted between January 2022 and January 2025, contributing 620 evaluable arterial segments. DSA was the reference standard for moderate-to-severe (>=50%) stenosis. In a separate analysis of 56 patients with matched carotid endarterectomy specimens, histopathology was the reference standard for plaque vulnerability. Results Across all arterial segments, territory-specific ultrasound assessment yielded a sensitivity of 79.56%, specificity of 81.79% and moderate agreement with DSA (kappa = 0.61). Diagnostic-performance point estimates were higher for extracranial segments assessed by CDU than for intracranial vertebrobasilar segments assessed by transcranial Doppler-based ultrasonography (sensitivity, 86.09% vs 62.50%; specificity, 85.20% vs 75.47%; kappa, 0.71 vs 0.38). For histologically confirmed carotid plaque vulnerability, CDU showed a sensitivity of 86.84%, specificity of 77.78% and accuracy of 83.93%; the corresponding CTA estimates were 31.58%, 100.00% and 53.57%. Discussion Ultrasound-based assessment showed complementary strengths across vascular territories. CDU demonstrated reliable performance for extracranial stenosis and higher sensitivity than routine CTA for vulnerable carotid plaques in this selected endarterectomy cohort, while transcranial Doppler-based ultrasonography provided additional haemodynamic information for intracranial vertebrobasilar disease despite lower diagnostic performance. These findings support territory-appropriate ultrasound as part of multimodal imaging rather than as a replacement for CTA or DSA.