2.3.2 3D semi-automated TEE aortic annulus measurement
Semi-automated aortic annulus measurements were made using the MVN
program, normally designed for detecting the mitral valve annulus. This
was achieved by scrolling the image in a multi-planar reconstruction
mode to maximal aortic valve opening, aligning the aorta in an upright
direction in the 2 orthogonal planes (figure 3, frame A and B) and
defining the 4 annular points of aortic valve insertion. The software
then automatically placed the remaining annular points with the operator
able to manually override this placement if there was disagreement in 8
long axis frames of the aorta (giving 16 points of annular placement)
Manual override of the automated placement of the annulus points did
occur in at least 2 or more places for the majority of patients and
tended to occur most often in the setting of acoustic shadowing by
valvular calcium. However any adjustment made was minor in nature and
did not add significantly to analysis time. The software then gave the
circumference and area of the aortic annulus and the area was converted
to a diameter by the equation
D= \(\sqrt{}\left(\frac{A}{\pi}\right)\times 2\) where D=diameter and
A=area.