Selection of landmarks
The ascending thoracic aorta is defined by international guidelines as
“the tubular portion of the ascending aorta beginning at the
sinotubular junction and extending to the brachiocephalic artery
origin”6,14. Study landmarks were selected based on
these guidelines. We considered selecting the aortic valve annulus as
our proximal landmark but decided that the sinotubular junction would be
a more consistently reproducible landmark due to the technical
difficulty involved in orienting the aortic valve cusps to identify the
annulus.