Electrical impedance tomography reconstruction for three-dimensional imaging of the prostate

Abstract

Transrectal electrical impedance tomography (TREIT) has been proposed as an adjunct modality for enhancing standard clinical ultrasound (US) imaging of the prostate. The proposed TREIT probe has an array of electrodes adhered to the surface of a cylindrical US probe that is introduced inside of the imaging volume. Reconstructing TREIT images in the open-domain geometry established with this technique poses additional challenges to those encountered with closeddomain geometries, present in more conventional EIT systems, because of the rapidly decaying current densities at increasing distances from the probe surface. We developed a finite element method (FEM)-based dual-mesh reconstruction algorithm which employs an interpolation scheme for linking a fine forward mesh with a coarse grid of pixels, used for conductivity estimation. Simulation studies using the developed algorithm demonstrate the feasibility of imaging moderately contrasting inclusions at distances of three times the probe radius from the probe surface and at multiple angles about the probe's axis. The large, dense FEM meshes used here require significant computational effort. We have optimized our reconstruction algorithm with multi-core processing hardware and efficient parallelized computational software packages to achieve a speedup of 9.3 times when compared to a more traditional Matlab-based, single CPU solution. The simulation findings and computational optimization provide a state-of-the-art reconstruction platform for use in further evaluating transrectal electrical impedance tomography.

Absolute Reconstructions Using Rotational Electrical Impedance Tomography for Breast Cancer Imaging

“…Our inverse implementation uses the dual-mesh method [25], which allows one to solve the Jacobian on a fine mesh while estimating the conductivity on a much coarser inverse mesh. This approach yields an electrical potential with high accuracy throughout the domain and enables one to reconstruct on any chosen inverse mesh.…”

Sensitivity study of an ultrasound coupled transrectal electrical impedance tomography system for prostate imaging

“…In this study, we describe our imaging hardware and analyze the sensitivity of it when combined with the reconstruction algorithm presented by Borsic et al [2]. …”

Anatomically accurate hard priors for transrectal electrical impedance tomography (TREIT) of the prostate

“…In the following sub-sections we discuss briefly forward modeling, parameter estimation, and details of the meshing/reconstruction approach are discussed. A first approach to meshing/reconstruction, which was proposed in Borsic et al 2010 and which does not incorporate US information, is briefly introduced for comparison purposes, followed by the novel approach which is proposed in the present work.…”

“…The electrodes appear as reflections on the periphery of the ultrasound images and are used to co-register US and EIT images. The flexible circuit of electrodes is wired to a custom 32 channel data acquisition system controlled through a LabView programming environment; a complete description of the system can be found in Wan et al 2010 and Borsic et al 2010. The probe is mounted on a rigid, articulated arm that locks the probe in place to ensure stable positioning during data acquisition.…”