To evaluate the histopathologic and computed tomography imaging features associated with irreversible electroporation (IRE) ablation performed in normal porcine kidneys. IRE is a nonthermal ablative tool that uses direct electrical pulses to create permanent “pores” in cell membranes and cell death. It does not affect the extracellular matrix.

Fifteen female swine were treated with IRE using acute (<24 hours), subacute (36 hours), and chronic (3 weeks) treatment settings. Unipolar IRE applicators were placed under CT guidance. The renal pelvis/calyx was included in 18 ablations. Imaging and histopathologic follow-up were performed.

A total of 29 ablations (19 acute, 4 subacute, and 6 chronic) were created. Acute/subacute ablations showed complete cortical necrosis without intervening live cells. The pelvic epithelium was necrotic with urothelial sloughing; pelvic extracellular matrix was intact. Chronic ablations showed cortical fibrosis, regenerating renal pelvic epithelium and intact pelvic extracellular matrix. No thermal injury, renal pelvic, or blood vessel injury was seen. Immediate postprocedure CT imaging demonstrated a hypodense nonenhancing lesion that persisted at 1 week. Of the 6 chronic lesions, 4 showed complete resolution at 3 weeks on imaging. No collecting system damage was seen.

This preliminary porcine study demonstrates the nonthermal and connective tissue sparing mechanism of action of IRE. These features may protect against collecting system damage after IRE ablation of renal tissue. IRE could therefore play an important role in ablation of centrally located renal tumors.