Cone Beam Computed Tomography: An Assessment of Renal Image Quality and Applicability for Percutaneous Renal Cryotherapy in a Swine Model

Abstract

To assess cone bean computed tomography (CBCT) for renal imaging in a phantom model, ex vivo kidney and an in vivo porcine percutaneous renal cyroablation (PRC). CBCT provides 3-dimensional sectional imaging without the space requirements, repositioning, and expenditure of computed tomography (CT). CBCT was focused on a radiological phantom with electron density of renal tissue and visualization was recorded. The ability of CBCT to image an ex vivo kidney in a water bath, with and without contrast, was then evaluated. An in vivo porcine animal model was then used to perform PRC and the scanner was evaluated in regard to image of the kidneys, a fiber-agarose pseudotumor, and guidance of the cryoprobe. Qualitative assessment of phantom images revealed sufficient contrast between the renal tissue and water densities. Images of the ex vivo porcine kidneys without contrast revealed limited renal architecture, whereas retrograde contrast revealed 3D images of renal shape and vascular/collecting system architecture visible in axial and sagittal planes. Noncontrast imaging facilitated precise needle guidance but was inadequate to consistently visualize ice-ball formation during cryoablation. At necropsy, all tumors were encompassed by the cryolesion with >1-cm margins, except for 1 pseudotumor that had been placed extracapsularly. CBCT is an imaging modality capable of excellent spatial resolution and soft-tissue sensitivity in a radiographic phantom and ex vivo and in situ porcine renal models. Based on our preliminary results, further refinements in image quality are required to improve soft tissue visualization to be applied to percutaneous renal cryoablation.