Graph-based 3D-ultrasound reconstruction of the liver in the presence of respiratory motion

Abstract

In this paper, we explore the feasibility of 3D ultrasound (US) reconstruction of the liver in the presence of respiratory motion using a minimally cumbersome acquisition protocol involving a commonly available tracked 2D+t wobbler US probe. We exploit measurements of the probe’s displacement against the skin to coarsely assign frames to their corresponding respiratory states. These assignments are refined using a graph representation of the spatial adjacency relationships and appearance continuity between the frames. Finally, frames providing the smallest motion variation, within a respiratory state, are first selected using a shortest path strategy, then passed to the reconstruction algorithm. Our method is fully based on tracked US imaging and does not require a pre-operative reference image. Moreover, no breathcontrol effort is required on the part of the patient, thereby limiting the complexity of the acquisition protocol. We tested our approach with an intercostal acquisition protocol, demonstrating enhancements in stability and the quality of liver reconstruction at different respiratory states, compared to a naive gating approach.