E1266. Carotid Ultrasound: A Pictorial Review From Atherosclerosis to Vasculitis
  1. Marta Flory; Stanford University
Waveform morphology on carotid ultrasound (US) is frequently overlooked by trainees, who are primarily focused on reviewing the peak systolic velocity numbers and ratios in assessing carotid stenosis. This educational exhibit reviews the underlying anatomy and physiology behind the arterial waveforms seen on carotid US (common carotid artery, internal carotid artery (ICA), external carotid artery (ECA), vertebral artery), the normal, expected appearance of these waveforms, and various etiologies of abnormal carotid US waveforms, including changes related to atherosclerosis, central etiologies (cardiogenic and device related), and local etiologies (trauma, iatrogenic, vasculitis) using a case-based approach.

Educational Goals / Teaching Points
The educational goals include reviewing normal waveform appearance in the head and neck vessels and discussing the underlying physiologic and anatomic factors that effect this waveform, and using a case-based approach to review various etiologies of abnormal waveforms, including technique related causes, atherosclerosis related causes, central causes, and local causes.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Carotid US is more than peak systolic velocity (PSV) and PSV ratios. This exhibit will review the anatomic structures (heart and vascular bed) and physiologic processes that give rise to and alter the normal arterial waveforms in the head and neck. It will subsequently use a case-based approach to illustrate pathology that may not necessarily cause PSV changes but can and should be diagnosed on carotid US. Cases include atherosclerosis-related findings (ICA stenosis with updated IAC vascular testing 2021 recommendations), findings of pre-steal, steal, dissection, acute occlusion and stroke, chronic occlusion with collateralization of cerebral flow via the ECA, temporal tap to confirm the waveform is from the ECA), central causes (cardiac-valvular, cardiomyopathy; cardiopulmonary support devices), intraaortic balloon pump, left ventricular assist device, extra-corporeal membrane oxygenation (ECMO), and local causes (trauma/iatrogenic, pseudoaneurysm, arterio-venous fistula), and vasculitis, postoperative changes. US, including grayscale, color and spectral Doppler, will be discussed, and CTA correlations are provided when illustrative to enhance understanding of US findings.

After reviewing this educational exhibit, reviewers should be familiar with the underlying anatomic and physiologic processes that impact the head and neck arterial waveforms, they should know the expected appearance of the normal waveforms, and be able to identify various causes of abnormal waveform morphologies, including related to atherosclerosis and it's complications, central pathology, and local pathology.