This study aims to establish international consensus-based quality criteria for contrast-enhanced ultrasound (CEUS) examinations of the liver and to develop a standardized tool for assessing CEUS image and examination quality. CEUS is an established imaging technique used in clinical practice for the characterization and assessment of focal liver lesions and other liver abnormalities. Despite its increasing use, there are currently no universally accepted or validated standards for evaluating the quality and reproducibility of CEUS examinations.
The primary objective of this project is therefore to identify robust and clinically relevant quality indicators for liver CEUS examinations through an international Delphi consensus process. The study focuses specifically on CEUS examinations performed in adult patients using the ultrasound contrast agent SonoVue®.
The project is divided into two work packages (WP). In Work Package 1 (WP1), the study team will first conduct a structured review of the available literature and discuss potential CEUS quality criteria within the research group. Based on this process, an initial catalogue of quality indicators relating to technical, procedural, and imaging characteristics relevant to liver CEUS examinations will be developed.
These proposed criteria will subsequently be evaluated through a multi-round Delphi process involving an international and interdisciplinary panel of experienced CEUS users and experts. A minimum of 35 panellists will participate across all Delphi rounds. Participants will rate their level of agreement with each proposed quality criterion using a 7-point Likert scale and may suggest additional criteria in the first round where appropriate. Newly proposed criteria supported by more than 10% of participants will be included in subsequent Delphi rounds.
During each round, panellists will receive anonymised feedback summarising the responses of the group and will be invited to re-evaluate the relevance of the proposed criteria. This iterative process will continue for at least three rounds or until predefined consensus criteria are achieved. Consensus will be defined as at least 70% agreement with a rating of 6 or higher on the Likert scale.
In Work Package 2 (WP2), the consensus-based quality criteria identified in WP1 will be operationalised into a comprehensive and standardised rating scale for CEUS image and examination quality assessment. Individual criteria will be grouped into broader data derived quality domains and transformed into practical assessment items and prompts. The proposed rating scale will use a three point scoring system (0="unacceptable quality", 1="acceptable quality", 3="High quality". The resulting rating tool will then be circulated among all Delphi panel members who completed all three Delphi rounds for final review and feedback to ensure clarity, applicability, and international usability.
The overall goal of this study is to improve standardization, quality assurance, and reproducibility in liver CEUS images and examinations. The developed consensus criteria and rating scale may support clinical practice, future research studies, multicentre collaborations, and educational initiatives by enabling more consistent evaluation of CEUS image quality across institutions and countries.
At least 6 years of active experience in ultrasound diagnostics in internal medicine, radiology, or a related clinical field
Independent performance of at least 5,000 ultrasound examinations Participation in structured CEUS training
Performance of at least 800 ultrasound examinations per year in routine clinical practice
Either: at least 100 independently performed CEUS examinations per year or more than 700 CEUS examinations in total
Failure to meet the inclusion criteria
The study population consists of internationally recognised CEUS experts from radiology and internal medicine with extensive clinical and scientific experience in ultrasound diagnostics. Participants are recruited from multiple countries to form an interdisciplinary expert panel. Inclusion requires expertise comparable to DEGUM Level III, including substantial ultrasound experience, regular performance of CEUS examinations, and involvement in CEUS training and/or research. Approximately 35 experts will be invited for the first Delphi round, with at least 20 expected to complete all rounds. The purposive sampling approach ensures a highly specialised panel aimed at achieving expert consensus rather than statistical representativeness.
Other
Prospective
Not listed
Which proposed contrast-enhanced ultrasound (CEUS) quality criteria achieve expert consensus, defined as ≥70% of panellists assigning a score of 6 ("agree") or 7 ("strongly agree") on a 7-point Delphi Likert scale, by the end of Round 3?
The number and individual content of proposed CEUS quality criteria that achieve predefined consensus after completion of the Delphi process. Consensus is defined as ≥70% of participating experts assigning a score of 6 ("agree") or 7 ("completely agree") on a 7-point Likert scale evaluating the statement: "This criterion indicates adequate quality of a CEUS examination." The rating is based on a 7-point Likert scale from 1 (strongly disagree) to 7 (strongly agree). Higher scores indicate stronger agreement that the criterion reflects adequate CEUS image quality.
What percentage of experts assigns a score of 6 or 7 on the 7-point Delphi Likert scale to each proposed CEUS quality criterion across the Delphi rounds?
For each proposed quality criterion, the percentage of participating experts assigning a rating of 6 ("agree") or 7 ("completely agree") on the 7-point Likert scale will be calculated and reported. The rating is based on a 7-point Likert scale from 1 (strongly disagree) to 7 (strongly agree). Higher scores indicate stronger agreement that the criterion reflects adequate CEUS image quality.
What are the median ratings for each proposed CEUS quality criterion on the 7-point Delphi Likert scale by the end of Delphi Round 3?
Median expert rating for each proposed CEUS quality criterion. Responses marked as "Outside of my expertise" will be excluded from calculation. The rating is based on a 7-point Likert scale from 1 (strongly disagree) to 7 (strongly agree). Higher scores indicate stronger agreement that the criterion reflects adequate CEUS image quality.
What are the interquartile ranges (IQRs) of expert ratings for each proposed CEUS quality criterion on the 7-point Delphi Likert scale across the Delphi rounds?
Interquartile range (IQR) of expert ratings for each proposed CEUS quality criterion. Lower IQR values indicate greater agreement among panellists. The rating is based on a 7-point Likert scale from 1 (strongly disagree) to 7 (strongly agree). Higher scores indicate stronger agreement that the criterion reflects adequate CEUS image quality.
How many quality domains are incorporated into the final CEUS image and examination quality rating scale derived from the consensus-based criteria?
Total number of domains derived from consensus-based CEUS quality criteria and incorporated into the final rating scale developed in Work Package 2.
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