Prospective application of real time 3D speckle tracking ultrasound system in stratifying abdominal aortic aneurysm rupture risk

Purpose: A diameter of abdominal aortic aneurysm (AAA) exceeding 5 cm is associated with significant rupture risk. Nevertheless, 1% of smaller aneurysms rupture yearly while other larger aneurysms remain stable and asymptomatic. Accordingly, rupture risk cannot reliably be determined by aneurysm size, but rather by assessing the mechanical stability of the aortic wall. The aim of this study was to investigate the prospective application of three-dimensional (3D) ultrasound in evaluating AAA morphology and biomechanical parameters.

Material and methods: The 3D ultrasound speckle tracking imaging method was validated by comparing it, in an in vitro silicone aneurysm model under pulsatile flow, with high speed laser scan micrometry and video photogrammetry. Subsequently, local displacement and strain parameters from AAAs of five male patients were analyzed using a real-time ECG-gated 3D-echocardiography Artida system.

Results: The methodological comparisons show that 3D ultrasound speckle tracking data significantly correlate with data obtained through laser scan micrometry and video photogrammetry, though the displacement values were slightly underestimated by 3D speckle tracking ultrasound. Evaluation of aortic aneurysms in patients presents considerable individual differences in local displacement and strain, although blood pressure values were within a similar range. Results suggest that 3D ultrasound was sensitive in interpreting biomechanical properties of the aortic wall and could define the individual variations in strain and displacement.

Conclusion: The accuracy of the real time 3D speckle tracking ultrasound system in evaluating biomechanical properties of the aortic wall, which are the most likely parameters to reliably assess AAA rupture risk, was investigated. The 3D ultrasound speckle tracking method proved to be highly precise in measuring vascular wall biomechanical changes, both in vitro and in vivo. Thus, this method promises to be a non-invasive, safe and financially attractive diagnostic tool to improve effective prevention and prompt intervention for aneurysms at risk of rupturing.

Fig. 1: 3D reconstruction of an infrarenal aortic aneurysm