Model-Based Correction of Tissue Compression for Tracked Ultrasound in Soft Tissue Image-Guided Surgery

Abstract

Acquisition of ultrasound data negatively affects image registration accuracy during image-guided therapy because of tissue compression by the probe. We present a novel compression correction method that models sub-surface tissue displacement resulting from application of a tracked probe to the tissue surface. Patient landmarks are first used to register the probe pose to pre-operative imaging. The ultrasound probe geometry is used to provide boundary conditions to a biomechanical model of the tissue. The deformation field solution of the model is inverted to non-rigidly transform the ultrasound images to an estimation of the tissue geometry before compression. Experimental results with gel phantoms indicated that the proposed method reduced the tumor margin modified Hausdorff distance (MHD) from 5.0 ± 1.6 to 1.9 ± 0.6 mm, and reduced tumor centroid alignment error from 7.6 ± 2.6 to 2.0 ± 0.9 mm. The method was applied to a clinical case and reduced the tumor margin MHD error from 5.4 ± 0.1 to 2.6 ± 0.1 mm and the centroid alignment error from 7.2 ± 0.2 to 3.5 ± 0.4 mm.

Toward a generic real-time compression correction framework for tracked ultrasound

“…We recently presented a method in [5] utilizing both probe tracking information in combination with a co-registered patient model in order to estimate the compression depth of the probe into the tissue during insonation and then to use that depth to correct the tracked ultrasound image poses using a biomechanical model-based approach. The novel method that we now propose does not use a patient-specific model derived from preoperative imaging, but instead uses a generic model to drive the correction as shown in Fig.…”

“…One group proposed using a force measurement apparatus to provide force boundary conditions to a tissue model [3,4], although force boundary conditions require some prior estimate of absolute material properties for the tissue. We recently proposed an alternative method which utilizes a biomechanical model-based correction which is driven by displacement boundary conditions provided by the position of a tracked ultrasound probe within a co-registered patient-specific organ surface from preoperative tomograms [5]. This method was shown to reduce ultrasound compressional error of nearly 1cm to approximately 2–3mm.…”

“…This correction is intended to produce ultrasound images in which the tissue structures can be rendered in their uncompressed biomechanical state so as to provide more accurate shape measurements or as a source of intraoperative data for geometric comparisons. The second goal was to compare the new method with the method previously described in [5] by deployment in phantoms and clinical data.…”

Simulation of Patient-Specific Deformable Ultrasound Imaging in Real Time

“…Alternatively, some effort has been focused on compensating for deformation. Pheiffer et al [4] defined a framework for correcting non-rigid tissue compression induced by the probe in US scanning, to allow for a more accurate volume estimation to be used in image guidance. Flach et al [5] used a FEM model around the contact areas and the known probe geometry to provide an accurate undeformed 3D volume.…”

Continuous ultrasound speckle tracking with Gaussian mixtures

“…Image-guided surgical applications are also foreseen by correlating dynamic image observations with advanced model-based biomechanics simulations of deformation [3].…”