Pulmonary trunk to aortic ratio
Citation, DOI & article data
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).
It is usually measured on axial (ideally orthogonal) images just prior to the pulmonary artery bifurcation.
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