4-D x 3-D ultrasound: real-time scan conversion, filtering, and display of displacement vectors with a motorized curvilinear transducer

Abstract

Recent research in the field of elastography has sought to expand displacement tracking to three dimensions. Once the 3-D volumes of displacement data have been obtained, they must be scan converted so that further processing, such as inversion methods to obtain tissue elasticity, can take place in Cartesian coordinates. This paper details an efficient and geometrically accurate algorithm to scan convert 3-D volumes of displacement vectors obtained from a motorized sector transducer. The proposed algorithm utilizes the physical scan geometry to convert the 3-D volumes of displacement data to both Cartesian coordinates and Cartesian displacements. Spatially varying filters are also proposed to prevent aliasing while minimizing data loss. Validation of the system has shown the algorithm to be correct to floating point precision, and the 3-D scan conversion and filtering can be performed faster than the native rate of data acquisition for the motorized transducer.

Miniaturized Endoscopic 2D US Transducer for Volumetric Ultrasound Imaging of the Auditory System

“…Despite a clear outline of the procedure, SC lacks methodology and remains cumbersome to perform. Reported implementations are actually transducer specific [19] as, for instance, there is no systematic and automatic way to derive the coordinate system transformation regardless of the used probe. Thanks to our expertise as roboticists, we propose in the following sections an adequate method for implementing SC that is not only meant to be straightforward for the nonspecialist reader but also can be extended to any transducer geometry.…”

“…Correctness of reconstructed volume's geometry measurement: Beyond assessing the resolution of the 2D B-mode images, this paper also aims to quantitatively evaluate the correctness of volumetric reconstruction since this new imaging platform is meant for medical purposes. To the best of the authors' knowledge, there is no agreed standard in the literature, and existing works on SC actually rely only on visual inspection for validation [17]- [19]. The only paper that presents such a quantitative test is a freehand US related work [31].…”

“…In scan-conversion US, frame acquisitions are conversely performed using a motor stage that includes an encoder. By directly refering to the geometry of the probe, this technique thus benefits from a high degree of precision as well as a short reconstruction time, both of which are of interest for diagnosis purposes [17]- [19]. Synthetic aperture has also been studied for 3D US using mechanically translated [20] or rotated [21] 2D transducers since it increases both the resolution and acquisition rate.…”

A hybrid camera- and ultrasound-based approach for needle localization and tracking using a 3D motorized curvilinear ultrasound probe

“…A large group of commercial 3D ultrasound imaging systems employs motorized curvilinear probes (Pospisil et al, 2010;Gao et al, 2016). Hence, 3D motorized curvilinear probes provide an attractive means to enable 3D ultrasound guidance of needle insertion interventions.…”

Dilatation parameterization for two-dimensional modeling of nearly incompressible isotropic materials

“…In many applications, especially those with ultrasound as the imaging modality, only two components of the displacements are available in a single plane and the inverse problem has to be solved for the unknown elasticity parameters within that plane. Since most ultrasound machines provide 2D images of the tissue, it is difficult to obtain 3D displacement maps with a high accuracy in the out-of-plane direction (Pospisil et al 2010). The objective, here, is to use the measured 2D displacements in a single plane to reconstruct the distribution of the mechanical parameters, such as Young's modulus.…”