Aortic Root

Measuring the Aortic Root

The aortic root refers to the proximal part of the aorta that lies between the aortic annulus and the sinotubular junction. The largest root measurement is obtained by measuring from one coronary sinus to another. Because of the curvature of the coronary sinuses, a 3D volumetric acquisition with thin slices allows for the most accurate and reproducible measurement. In principle, the measurement can be made from images that are acquired either parallel or perpendicular to the aorta. However, in practice, perpendicular images often yield the most reliable measurement.  The main advantage of perpendicular imaging is that it allows for the selection of the pair of coronary sinuses yielding the greatest measurement.

Sometimes the results from MRI are discordant with those of echocardiography, and in these cases the MRI measurement is often larger. This may be because the echocardiographic measurement is most easily made from the right coronary cusp to the noncoronary cusp, but in some patients the distance from the right coronary cusp to the left coronary cusp yields the largest measurement. Also, in MRI, the measurement is made from outer wall to outer wall, whereas in echocardiography it is made from inner wall to outer wall.

Tb.  Characterization of Aortic Root Size
Structure Normal (cm) Mild (cm) Moderate (cm) Severe (cm)
Aortic root 3.5 4.0-4.4 4.5-4.9 ≥5.0

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