Prenatal events such as intrauterine growth restriction have been shown to be associated with an increased thickness of
abdominal aorta in the fetus. Therefore the measurement of abdominal aortic intima-media thickness (aIMT) has been
recently considered a sensitive marker of artherosclerosis risk. To date measure of aortic diameter and of aIMT has been
performed manually on US fetal images, thus being susceptible to intra- and inter- operator variability. This work
introduces an automatic algorithm that identifies abdominal aorta and estimates its diameter and aIMT from videos
recorded during routine third trimester ultrasonographic fetal biometry.
Firstly, in each frame, the algorithm locates and segments the region corresponding to aorta by means of an active
contour driven by two different external forces: a static vector field convolution force and a dynamic pressure force.
Then, in each frame, the mean diameter of the vessel is computed, to reconstruct the cardiac cycle: in fact, we expect the
diameter to have a sinusoidal trend, according to the heart rate. From the obtained sinusoid, we identify the frames
corresponding to the end diastole and to the end systole. Finally, in these frames we assess the aIMT. According to its
definition, we consider as aIMT the distance between the leading edge of the blood-intima interface, and the leading
edge of the media-adventitia interface on the far wall of the vessel. The correlation between end-diastole and end-systole
aIMT automatic and manual measures is 0.90 and 0.84 respectively.