A Dual-Modal CT/US Kidney Phantom Model for Image-Guided Percutaneous Renal Access

Abstract

Percutaneous renal access (PRA) is a crucial step in some minimally invasive kidney interventions. During this step, the surgeon inserts a needle through the skin until the kidney target site using fluoroscopy and ultrasound imaging. Recently, new concepts of enhanced image-guided interventions have been introduced in these interventions. However, their validation remains a challenging task. Phantom models have been presented to solve such challenge, using realistic anatomies in a controlled environment. In this work, we evaluate the accuracy of a porcine kidney phantom for validation of novel dual-modal computed tomography (CT)/ultrasound (US) image-guided strategies for PRA. A porcine kidney was combined with a tissue mimicking material (TMM) and implanted fiducial markers (FM). While the TMM mimics the surrounding tissues, the FM are used to accurately assess the registration errors between the US and CT images, providing a valid ground-truth. US and CT image acquisitions of the phantom model were performed and the FM were manually selected on both images. A rigid alignment was performed between the selected FM, presenting a root-mean-square error of 1.1 mm. Moreover, the kidney was manually segmented, presenting volumes of 203 ml and 238 ml for CT and US, respectively. The initial results are promising on achieving a realistic kidney phantom model to develop new strategies for PRA, but further work to improve the manufacturing process and to introduce motion and anatomical artifacts in the phantom is still required.