Pulmonary Artery to Aortic Diameter Ratio


Calculate MPa:Ao and determined if enlarged








 Jay Nance

Panel Chair

 Carlo De Cecco

Panel Reviewers

 Cardiac Panel


 Creative Commons 4.0

Status  Public Commenting

Clinical Implementation

Value Proposition

Pulmonary artery size is an imperfect imaging biomarker of pulmonary hypertension, but it has shown prognostic value in a variety of clinical situations. Cutoffs for abnormal values have been proposed and validated. Automated quantification would save the interpreting physician time via elimination of manual measurements, would prevent detection errors (missing enlarged pulmonary arteries), and would provide structured quantitative data, which could be used in later studies or risk-stratification schemes.


All patients undergoing CT examinations through the level of the main pulmonary artery should have automated quantification of arterial diameter, which should then be automatically populated into the radiology report or a report supplement. This use case will focus specifically on relevant cardiac imaging modalities, ie, electrocardiogram (ECG)-synchronized coronary artery calcium scoring, coronary CT angiography (CCTA), and full-chest CT angiography (triple rule-out scans).

Workflow Description

A patient receives ECG-synchronized CT of the chest and heart. An algorithm retrieves a volumetric imaging data set and accessible electronic medical record data, including age, sex, and body mass index. The algorithm executes and returns the main pulmonary artery to aortic diameter ratio (MPA:Ao). If the ratio or absolute value indicate enlarged arteries, alert the user. The algorithm returns all values, which could populate the report (possibly within a supplement containing other quantitative data). The algorithm flags abnormal values.

Considerations for Dataset Development

Procedures(s): ECG-synchronized CT, Chest

Sex at Birth: {Male, Female}


Age (years): [15,90]


Body Mass Index (kg/m2): [10,52]


Body Surface Area: varied


Aortic Diameter (mm): [20,40]


Abnormalities: {Congenital heart disease, ventricular septal defects}


Interventions: {Congenital heart disease repair, mitral valve replacements}


Contrast: {Contrast-enhanced (CCTA), non-contrast enhanced applications}

Technical Specifications




ECG-synchronized CT, Chest

Data Type




Body Region


Anatomic Focus



Primary Outputs

Pulmonary Artery to Aortic Diameter Ratio

RadElement ID



Main pulmonary artery to aortic diameter ratio (MPA:Ao)

Data Type


Value Set




Public Commenting

Use cases are meant to be a primary vehicle for distributing clinical information to the developer community. They pinpoint precise scenarios within radiology workflows where potential automation could add noticeable value and establish standards for interpreting and passing corresponding common data elements. Implementing effective standards requires the perspective from all stakeholders. So to that end, we encourage your feedback on use cases.

To submit comments, please email DSIUseCases@acr.org with the use case title(s) and relevant comments by January 1, 2019. If more convenient, you may also download this use case and comment directly on the PDF. Just attach the PDF copy on the email.