Speeding up Carotid Stenosis

Refined Diagnostic Criteria for Carotid Artery Stenosis: A Study by IAC Vascular Testing

In 2014, the Intersocietal Accreditation Commission (IAC) Vascular Testing released a White Paper addressing significant inconsistencies in the criteria used to interpret the degree of internal carotid artery (ICA) stenosis in carotid duplex ultrasound examinations. This document highlighted the historical context and the potential clinical impact of such variability on the reliability and comparability of carotid stenosis measurements. These inconsistencies have significant implications for clinical decision-making, potentially affecting the accuracy and comparability of diagnostic outcomes across different medical facilities.

Background and Objectives

The primary objective of the IAC Vascular Testing’s initiative was to mitigate this variability. As an initial measure, they recommended that vascular laboratories not utilizing validated, internally-derived stenosis criteria adopt the diagnostic criteria proposed by the Society of Radiologists in Ultrasound (SRU) Consensus Conference. This recommendation aimed to create a standardized approach to diagnosing carotid artery stenosis, thereby improving the consistency and reliability of diagnostic outcomes.

Subsequently, IAC Vascular Testing embarked on a research study to validate these criteria using “real world” carotid duplex scans from IAC-accredited vascular labs and contrast arteriography. The study aimed to assess the validity of the SRU Consensus Conference criteria and potentially refine them or develop distinct criteria suitable for IAC-accredited facilities performing carotid duplex examinations. This initiative reflects IAC Vascular Testing’s commitment to enhancing the diagnostic accuracy and clinical utility of carotid duplex ultrasound examinations.

Study Findings

The study, recently published in the peer-reviewed journal Vascular Medicine, confirmed the findings of prior research. Notably, it was observed that the SRU peak systolic velocity (PSV) threshold of 125 cm/sec for a 50% diameter-reducing stenosis of the ICA was overly sensitive and lacked specificity and accuracy. The study supports adopting a higher PSV threshold value of 180 cm/sec. However, the sample size for high-grade stenoses was insufficient to recommend changes to the SRU criteria for higher degrees of internal carotid stenosis (70% and 80%).

The findings highlight the importance of using validated diagnostic criteria to ensure accurate and consistent measurements of carotid artery stenosis. This consistency is crucial for clinical decision-making and patient management, particularly in the context of vascular diseases where accurate diagnosis is essential for effective treatment planning.


Based on these findings, IAC Vascular Testing now strongly recommends the general adoption of modified SRU criteria, which incorporate the higher PSV threshold value of 180 cm/sec for 50% diameter-reducing ICA stenosis. The IAC acknowledges that there may be selected cases with 50-69% ICA stenosis where PSV is less than 180 cm/sec, but other parameters such as an elevated ICA/CCA PSV ratio greater than 2.0, significant plaque, and post-stenotic turbulence should also be considered. Therefore, a comprehensive evaluation of all Doppler and gray scale parameters is essential for interpreting the degree of ICA stenosis.

The adoption of these refined criteria is expected to enhance the accuracy of carotid artery stenosis diagnosis, thereby improving clinical outcomes for patients. This approach underscores the importance of continuous research and refinement of diagnostic criteria to align with the latest scientific evidence and clinical practice needs.


IAC Vascular Testing strongly advocates for the adoption of these modified criteria for carotid interpretation. Broad acceptance of this recommendation is expected to enhance the accuracy in detecting clinically relevant ICA stenoses and reduce variability in grading ICA stenosis in duplex studies performed by IAC-accredited vascular labs. Implementing these refined diagnostic criteria will ultimately improve the clinical value of carotid duplex ultrasound examinations, ensuring more consistent and reliable patient outcomes.

For those looking to further their knowledge and expertise in vascular ultrasound, the Institute for Advanced Medical Education (IAME) is a definitive resource. IAME offers comprehensive training and up-to-date continuing medical education (CME) for sonographers and physicians with annual memberships or for those looking to lock in a lifetime of value and learning, lifetime physician memberships or lifetime sonographer memberships.  These programs are designed to equip healthcare professionals with the latest knowledge and skills needed to excel in vascular ultrasound diagnostics.

To learn more about vascular ultrasound and to stay updated with the latest advancements in this field, visit IAME’s vascular ultrasound page. Here, you will find a wealth of resources and educational opportunities tailored to meet the needs of healthcare professionals dedicated to providing high-quality patient care.

By engaging with the educational offerings at IAME, physicians and sonographers can enhance their proficiency in vascular ultrasound, ensuring they are well-prepared to implement the latest diagnostic criteria and improve patient outcomes. For more information and to explore the available courses, visit IAME’s vascular ultrasound courses page.


  1. IAC Vascular Testing White Paper (2014)
  2. Society of Radiologists in Ultrasound (SRU) Consensus Conference
  3. Published results in Vascular Medicine
IAC updated criteria for ultrasound diagnosis of carotid stenosis, Speeding up Carotid Stenosis

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