Pulmonary trunk to aortic ratio

Last revised by Daniel J Bell on 21 Jul 2022

The pulmonary trunk to aortic ratio (PA:A), also known as main pulmonary artery to aorta ratio (MPA:A), is a measurement that can be made on CT and MRI scans and, in some instances on echocardiography 3. In most instances, a normal ratio in adults is taken 1:1 or less, and with ratios greater than that suggests:

However, some studies state that it can be normal up to 1.09:1 in the pediatric population (with some reports suggesting the cut off ratio in children being closer to 1.3:1 8).

Measurement

It is usually measured on axial (ideally orthogonal) images just prior to the pulmonary artery bifurcation.

 

ADVERTISEMENT: Supporters see fewer/no ads

Updating… Please wait.

 Unable to process the form. Check for errors and try again.

 Thank you for updating your details.