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Ultrasonographic Measurement of Carotid Intimal-Medial Thickness as an Assessment of Subclinical Atherosclerosis

Policy Number: MP-245

Latest Review Date: May 2024

Category:  Medicine                                                              


Ultrasonographic measurement of carotid artery intimal-medial thickness (CIMT) as a technique for identifying subclinical atherosclerosis for use in the screening, diagnosis, or management of atherosclerosis is considered investigational.


Ultrasonographic measurement of carotid intima-medial (or intimal-media) thickness (CIMT) refers to the use of B-mode ultrasound to determine the thickness of the 2 innermost layers of the carotid artery wall, the intima and the media. Detection and monitoring of intima-medial thickening, which is a surrogate marker for atherosclerosis, may provide an opportunity to intervene earlier in atherogenic disease and/or monitor disease progression.

Coronary Heart Disease

Heart disease is the leading cause of mortality in the United States, accounting for more than half of all deaths. Coronary heart disease (CHD), also known as coronary artery disease, is the most common cause of heart disease. In a 2024 update on heart disease and stroke statistics from the American Heart Association, it was estimated that 720,000 Americans have a new coronary attack (first hospitalized myocardial infarction or CHD death) and 335,000 have a recurrent attack annually. An estimated 20.5 million Americans ≥20 years of age have CHD. 

Established major risk factors for CHD have been identified by the National Cholesterol Education Program (NCEP) Expert Panel.  These risk factors include elevated serum levels of low density lipoprotein (LDL) cholesterol, total cholesterol, and reduced levels of high-density lipoprotein (HDL) cholesterol.  Other risk factors include a history of cigarette smoking, hypertension, family history of premature CHD, and age. 


The third report of the NCEP Adult Treatment Panel (ATP III) establishes various treatment strategies to modify the risk of CHD, with emphasis on target goals of LDL cholesterol.  Pathology studies have demonstrated that levels of traditional risk factors are associated with the extent and severity of atherosclerosis. ATP III recommended the use of the Framingham criteria to further stratify those patients with 2 or more risk factors for more intensive lipid management. However, at every level of risk factor exposure, there is substantial variation in the amount of atherosclerosis, presumably related to genetic susceptibility and the influence of other risk factors.  Therefore, there has been interest in identifying a technique that can improve the ability to diagnose those at risk of developing CHD, as well as measure disease progression, particularly for those at intermediate risk. 

The carotid arteries can be well-visualized by ultrasonography, and ultrasonographic measurement of the carotid intima-media thickness (CIMT) has been investigated as a technique to identify and monitor subclinical atherosclerosis. B-mode ultrasound is most commonly used to measure CIMT. CIMT is measured and averaged over several sites in each carotid artery. Imaging the far wall of each common carotid artery yields more accurate and reproducible CIMT measurements than imaging near wall. Two echogenic lines are produced, representing the lumen-intima interface and the media-adventitia interface. The distance between these 2 lines constitutes the CIMT.


The most recent literature review was performed through March 18, 2024.

Summary of Evidence

For individuals who are undergoing cardiac risk assessment who receive ultrasonic measurement of carotid intima-media (or intimal-medial) thickness (CIMT), the evidence includes large cohort studies, case-control studies, and systematic reviews. Relevant outcomes are test accuracy and morbid events. Some studies have correlated increased CIMT with other commonly used markers for risk of coronary heart disease (CHD) and with risk for future cardiovascular (CV) events. Lorenz et al (2012) found in their meta-analysis that CIMT was associated with increased CV events, although CIMT progression overtime was not associated with increased CV event risk. Peters et al (2012) found that the added predictive value of CIMT was modest, and the ability to reclassify patients into clinically relevant categories was not demonstrated. The results from these reviews and other studies have demonstrated the predictive value of CIMT is uncertain and that the predictive ability for any level of population risk cannot be determined with precision. Also, available studies do not define how the use of CIMT in clinical practice improves outcomes. There is no scientific literature that directly tests the hypothesis that measurement of CIMT results in improved patient outcomes and no specific guidance on how measurements of CIMT should be incorporated into risk assessment and risk management. The objective of 1 study, however, was to define “normal” CIMT progression in low to moderate CV risk patients. Study results showed definite patterns related to various factors that could be used as a tool to earlier identify patients at increased CV risk, but patient outcomes were not assessed. The evidence is insufficient to determine that the technology results in an improvement in the net health outcome.

Practice Guidelines and Position Statements

American College of Cardiology and American Heart Association

A 2013 guideline on the assessment of cardiovascular risk from the American College of Cardiology and the American Heart Association (ACC/AHA) does not recommend CIMT for routine risk assessment of a first atherosclerotic CVD event. (ACC/AHA Class III: no benefit, LOE: B). This differs from the previous 2010 version of the ACC/AHA guidelines for assessment of cardiovascular risk, which indicated CIMT might be reasonable for assessing CV risk in intermediate risk asymptomatic adults.

American Association of Clinical Endocrinologists 

The American Association of Clinical Endocrinologists and American College of Endocrinology published 2017 guidelines stating that CIMT could be applied as a risk stratification tool in determining the need for more aggressive preventive strategies against CVD (Grade B; BEL 2)—but that it should not be performed routinely.

American Society of Echocardiography

In 2008, the American Society of Echocardiography (ASE) consensus statement, endorsed by the Society for Vascular Medicine, stated that CIMT is a feature of arterial wall aging "that is not synonymous with atherosclerosis, particularly in the absence of plaque." The statement recommended measurement of both CIMT and carotid plaque by ultrasound "for refining CVD [cardiovascular disease] risk assessment in patients at intermediate cardiovascular disease risk (Framingham Risk Score 6%-20%) without established CHD [coronary heart disease], peripheral arterial disease, cerebrovascular disease, diabetes mellitus, or abdominal aortic aneurysm." However, the Society acknowledged that "More research is needed to determine whether improved risk prediction observed with CIMT or carotid plaque imaging translates into improved patient outcomes." The recommendations made in the 2008 consensus statement were endorsed in ASE's 2020 guideline– Recommendations for the Assessment of Carotid Arterial Plaque by Ultrasound for the Characterization of Atherosclerosis and Evaluation of Cardiovascular Risk. Authors of the 2020 guideline also note the following: "Since the largest portion of CIMT (approximately 99% in healthy individuals and approximately 80% when diseased) consists of the medial layer, CIMT has not been shown to consistently add to CVD risk prediction."

U.S. Preventive Services Task Force Recommendations

In 2009, the U.S. Preventive Services Task Force (USPSTF) published a systematic review of CIMT within the scope of a larger recommendation on the use of nontraditional risk factors in coronary heart disease risk assessment. USPSTF could not draw conclusions on the applicability of CIMT to the intermediate-risk population at large outside the research setting. The USPSTF summary of recommendation specific to CIMT stated that: “… the current evidence is insufficient to assess the balance of benefits and harms of using … [CIMT] … to screen asymptomatic men and women with no history of CHD to prevent CHD events.” USPSTF identified the following research need: “The predictive value … of carotid IMT … should be examined in conjunction with traditional Framingham risk factors for predicting CHD events and death.”

In 2018, the USPSTF published a recommendation statement on using nontraditional risk factors to assess risk of CVD; CIMT was not mentioned in this recommendation.


Carotid intimal medial thickness (CIMT), B-mode ultrasound, intimal medial thickness, IMT, atherosclerosis, ultrasonographic measurement, SonoCalc®, Cardioscan


In February 2003, SonoCalc® (Sonosite) was cleared for marketing by the FDA through the 510(k) process.  The FDA determined that this software was substantially equivalent to existing image display products for use in the automatic measurement of the intima media thickness of the carotid artery from images obtained from ultrasound systems.  Subsequently, several other devices have been approved through the 510(k) process.


Coverage is subject to member’s specific benefits.  Group-specific policy will supersede this policy when applicable.

ITS: Home Policy provisions apply

FEP contracts: Special benefit consideration may apply.  Refer to member’s benefit plan. 


CPT code:


Quantitative carotid intima media thickness and carotid atheroma evaluation, bilateral

93998 Unlisted noninvasive vascular diagnostic study

It is possible that providers may incorrectly use the following CPT code:


Duplex scan of extracranial arteries; complete bilateral study


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Medical Policy Group, August 2005 (3)

Medical Policy Administration Committee, August 2005

Available for comment August 27-October 10, 2005

Medical Policy Group, August 2006 (1)

Medical Policy Group, August 2007(1)

Medical Policy Group, March 2009 (4)

Medical Policy Group, July 2009 (3)

Medical Policy Group, July 2010 (1): Policy updated, no coverage change

Medical Policy Group, July 2011 (1): Update to Description, Key Points and References

Medical Policy Group, July 2012 (1): Update to Key Points and References related to MPP update; no change to policy statement

Medical Policy Group, July 2013 (4): 2013 Update to Key Points and References related to Diagnostic Utility

Medical Policy Panel, July 2014

Medical Policy Group, July 2014 (4): Updated Key Points, Practice Guidelines and References. No change to policy statement at this time.

Medical Policy Group, November 2014: 2015 Annual Coding update. Added code 93895 to current coding

Medical Policy Panel, July 2015

Medical Policy Group, July 2015 (4): Updates to Description, Key Points, Key Words, Coding, and References. No change to policy statement. Moved CPT 93799 to previous coding section

Medical Policy Group, January 2016 (4): Added CPT code 93880 to Coding section.

Medical Policy Group, April 2016 (4): Added the statement “It is possible that providers may incorrectly use the following CPT code”.

Medical Policy Panel, January 2017

Medical Policy Group, January 2017(4): Updates to Description, Key Points, and References. No change to policy statement.

Medical Policy Group, October 2017 (4): Added Key Word Cardioscan.

Medical Policy Panel, May 2018

Medical Policy Group, May 2018 (4): Updates to Description, Key Points, and References. No change to policy statement.

Medical Policy Panel, May 2019

Medical Policy Group, May 2019 (4): Updates to Description, Key Points, and Coding. Removed Previous coding section with code 93799.

Medical Policy Panel, May 2020

Medical Policy Group, May 2020 (4): Updates to Key Points and References. No change to policy statement.

Medical Policy Panel, November 2020: 2021 Annual Coding Update.  Added CPT code 93998 to Current Coding.  Moved deleted CPT code 0126T to Previous coding section.

Medical Policy Panel, May 2021

Medical Policy Group, May 2021 (4): Updates to Description, Key Points, Practice Guidelines, Governing Bodies and References. Policy statement updated to remove “not medically necessary,” no change to policy intent.

Medical Policy Panel, May 2022

Medical Policy Group, May 2022 (4): Updates to Description, Key Points and References.

Medical Policy Panel, May 2023

Medical Policy Group, May 2023 (4): Updates to Description, Key Points, Benefit Application, Current Coding and References.

Medical Policy Panel, May 2024

Medical Policy Group, May 2024 (4): Updates to Description, Key Points, and References.  No change to policy statements.

This medical policy is not an authorization, certification, explanation of benefits, or a contract. Eligibility and benefits are determined on a case-by-case basis according to the terms of the member’s plan in effect as of the date services are rendered. All medical policies are based on (i) research of current medical literature and (ii) review of common medical practices in the treatment and diagnosis of disease as of the date hereof. Physicians and other providers are solely responsible for all aspects of medical care and treatment, including the type, quality, and levels of care and treatment.

This policy is intended to be used for adjudication of claims (including pre-admission certification, pre-determinations, and pre-procedure review) in Blue Cross and Blue Shield’s administration of plan contracts.

The plan does not approve or deny procedures, services, testing, or equipment for our members. Our decisions concern coverage only. The decision of whether or not to have a certain test, treatment or procedure is one made between the physician and his/her patient. The plan administers benefits based on the member’s contract and corporate medical policies. Physicians should always exercise their best medical judgment in providing the care they feel is most appropriate for their patients. Needed care should not be delayed or refused because of a coverage determination.

As a general rule, benefits are payable under health plans only in cases of medical necessity and only if services or supplies are not investigational, provided the customer group contracts have such coverage.

The following Association Technology Evaluation Criteria must be met for a service/supply to be considered for coverage:

1. The technology must have final approval from the appropriate government regulatory bodies;

2. The scientific evidence must permit conclusions concerning the effect of the technology on health outcomes;

3. The technology must improve the net health outcome;

4. The technology must be as beneficial as any established alternatives;

5. The improvement must be attainable outside the investigational setting.

Medical Necessity means that health care services (e.g., procedures, treatments, supplies, devices, equipment, facilities or drugs) that a physician, exercising prudent clinical judgment, would provide to a patient for the purpose of preventing, evaluating, diagnosing or treating an illness, injury or disease or its symptoms, and that are:

1. In accordance with generally accepted standards of medical practice; and

2. Clinically appropriate in terms of type, frequency, extent, site and duration and considered effective for the patient’s illness, injury or disease; and

3. Not primarily for the convenience of the patient, physician or other health care provider; and

4. Not more costly than an alternative service or sequence of services at least as likely to produce equivalent therapeutic or diagnostic results as to the diagnosis or treatment of that patient’s illness, injury or disease.