Contrast Enhancement Patterns after Irreversible Electroporation: Experimental Study of CT Perfusion Correlated to Histopathology in Normal Porcine Liver

Abstract

PurposeTo analyze ablated tissue zones after irreversible electroporation (IRE) of porcine liver using computed tomography (CT) perfusion imaging with histopathologic correlation. Materials and MethodsUnder ultrasound and CT guidance, 10 IRE ablations were performed percutaneously in three Yorkshire pigs using a single bipolar electrode. CT perfusion imaging was performed in all pigs immediately after ablation and on day 2. Pathologic sections were prepared for correlation with histopathology (hematoxylin-eosin and terminal deoxynucleotidyl transferase dUTP nick end labeling stains, 5-mm–thick slices). The short diameter of different enhancing zones on CT was correlated with the gross specimen. ResultsCT perfusion images showed three differently enhancing zones: zone 1, inner nonenhancing zone; zone 2, middle well-defined progressive internal enhancement zone; and zone 3, outer ill-defined arterial enhancement zone with rapid washout. On histopathology, zone 1 showed a strong correlation with a pale zone, and zone 2 correlated with a red zone, together accounting for the extent of cell death. Zone 3 was outside of the ablation zone and contained inflammatory cells. Each enhancing zone had different perfusion parameters. ConclusionsCT perfusion imaging in the acute setting effectively demonstrates histopathologic tissue zones after IRE ablation. Zone 2 is unique to IRE not seen in thermal ablation, characterized by progressive intra-zonal enhancement, and its outer boundary defines the extent of cell death.