Standardized ultrasound evaluation of carotid stenosis for clinical trials: University of Washington Ultrasound Reading Center

Abstract

IntroductionSerial monitoring of patients participating in clinical trials of carotid artery therapy requires noninvasive precision methods that are inexpensive, safe and widely available. Noninvasive ultrasonic duplex Doppler velocimetry provides a precision method that can be used for recruitment qualification, pre-treatment classification and post treatment surveillance for remodeling and restenosis. The University of Washington Ultrasound Reading Center (UWURC) provides a uniform examination protocol and interpretation of duplex Doppler velocity measurements.MethodsDoppler waveforms from 6 locations along the common carotid and internal carotid artery path to the brain plus the external carotid and vertebral arteries on each side using a Doppler examination angle of 60 degrees are evaluated. The UWURC verifies all measurements against the images and waveforms for the database, which includes pre-procedure, post-procedure and annual follow-up examinations. Doppler angle alignment errors greater than 3 degrees and Doppler velocity measurement errors greater than 0.05 m/s are corrected.ResultsAngle adjusted Doppler velocity measurements produce higher values when higher Doppler examination angles are used. The definition of peak systolic velocity varies between examiners when spectral broadening due to turbulence is present. Examples of measurements are shown.DiscussionAlthough ultrasonic duplex Doppler methods are widely used in carotid artery diagnosis, there is disagreement about how the examinations should be performed and how the results should be validated. In clinical trails, a centralized reading center can unify the methods. Because the goals of research examinations are different from those of clinical examinations, screening and diagnostic clinical examinations may require fewer velocity measurements.

Recomendação para a Quantificação pelo Ultrassom da Doença Aterosclerótica das Artérias Carótidas e Vertebrais: Grupo de Trabalho do Departamento de Imagem Cardiovascular da Sociedade Brasileira de Cardiologia – DIC - SBC

“…Atualmente vários exames podem ser realizados para a avaliação da doença das artérias carótidas, como a arteriografia convencional, a angiografia por ressonância nuclear magnética (ARNM), a angiotomografia (CTA) e a USV 88 . Nas últimas três décadas, a USV tornou-se o método mais utilizado para a avaliação das artérias carótidas extracranianas 2,89 . Isso se justifica por tratar-se de um método não invasivo, que não utiliza radiação ou contraste, fornece informações anatômicas e hemodinâmicas, tem boa reprodutibilidade, portabilidade e custo inferior aos demais exames diagnósticos.…”

“…A visualização da placa é imprescindível para o diagnóstico da estenose uma vez que condições hemodinâmicas diversas podem cursar com velocidades elevadas ou reduzidas independentemente da presença de estenoses. com o fluxo 89 . Tola e cols.…”

Institutional Differences in Carotid Artery Duplex Diagnostic Criteria Result in Significant Variability in Classification of Carotid Artery Stenoses and Likely Lead to Disparities in Care

“…Although standardized protocols to perform carotid duplex ultrasound have been published, 5 no uniform criteria to interpret these studies have been mandated and implemented by all laboratories nationwide. For example, the Carotid Duplex Consensus Criteria did propose specific peak systolic velocities consistent with a 50% to 69% and ≥70% carotid stenosis.…”

Carotid Artery Stenosis

“…14 Other consensus groups have also addressed the strengths and weakness of duplex ultrasound, offered primary and alternate criteria, and discussed difficulties attributable to long lesions, tandem lesions, contralateral disease, and heterogeneity of techniques such as varying Doppler angles. 6,13 The recognition that a comprehensive evaluation goes beyond the peak systolic velocity to diagnose and grade a stenosis also is not new. Evaluations of lesions before, during, and after a stenosis are found in the American Institute of Ultrasound in Medicine/ American College of Radiology and Intersocietal Commission for Accreditation of Vascular Laboratories guidelines.…”

“…12 Details of a single institution clinical trials standard was also recently published by the University of Washington Ultrasound Reading Center. 13 Society of Radiologists in Ultrasound Multi-Disciplinary Consensus Panel managed to agree on a set of criteria to grade a short-length unilateral carotid artery stenosis 6 that has been adopted by many Intersocietal Commission for Accreditation of Vascular Laboratories-accredited laboratories (Heather Gornik, MD, personal communication), but its acceptance is far from mainstream.…”